JP2009142654A - Endoscope apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image of a subject whose intensity largely varies as an image in a state where light is appropriately modulated. <P>SOLUTION: A CCD driving circuit 31 varies a pulse-like signal and transmits the signal to a CCD 19 to vary the sensitivity of the CCD 19. A photometric circuit 36 photometers the signal outputted from the CCD 19. A sensitivity control circuit 32 controls the sensitivity of the CCD 19 by controlling the charge amplification factor of the CCD 19 based on the result of the photometry by the photometric circuit 36. A photometry correction circuit 37 corrects the result of the photometry by the photometric circuit 36 based on the charge amplification factor from the sensitivity control circuit 32. A diaphragm control circuit 52 controls a diaphragm 51 based on the photometric signal corrected by the photometry correction circuit 37. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an endoscope apparatus that obtains an image by an image sensor that images a subject by accumulating electric charges.

  2. Description of the Related Art Conventionally, an endoscope apparatus is generally configured by an endoscope such as an electronic endoscope having a solid-state image sensor, a processor, a light source device, and a monitor. In such a conventional endoscope apparatus, an insertion portion of an endoscope is inserted into a body cavity, and light is emitted from a light source device that is irradiated to a subject via a light guide built in the endoscope. The reflected light is photoelectrically converted by a solid-state imaging device mounted at the distal end of the endoscope, an output signal obtained by the photoelectric conversion is signal-processed by a processor, and this signal is displayed on a monitor.

  In recent years, an excitation light is irradiated onto an observation target site of a living tissue, and autofluorescence generated from the living tissue or fluorescence of a drug injected into the living body is captured as a two-dimensional image by the excitation light. Techniques for diagnosing disease states such as cancer (type of disease, infiltration range, etc.) are being used, and fluorescence observation apparatuses for performing this fluorescence observation have been developed.

  In auto-fluorescence, when a living tissue is irradiated with excitation light, fluorescence is generated on the longer wavelength side of the excitation light by the excitation light. Examples of fluorescent substances in living bodies include NADH (nicotinamide adenine nucleotide), FMN (flavin mononucleotide), collagen, and the like. Recently, the correlation between endogenous substances that generate such fluorescence and diseases is becoming clear, and by observing these fluorescences, it is possible to diagnose cancer and the like.

  In the fluorescence of drugs, HpD (hematoporphyrin), Photofrin, ALA (δ-amino levulinic acid) and the like are used as fluorescent substances to be injected into a living body. These drugs have specific accumulation properties in cancer and the like, and the lesions can be diagnosed by injecting them into the living body in advance and observing the fluorescence. Alternatively, there is a method in which a fluorescent substance is added to a monoclonal antibody and the fluorescent substance is accumulated in a lesion by an antigen-antibody reaction.

  As an example of a fluorescence observation apparatus, for the purpose of obtaining a single-color fluorescence image, the fluorescence observation apparatus is mounted on the endoscope tip so that the screen average of the fluorescence image is constant, that is, the brightness average of the monitor is constant. There is one that variably controls the sensitivity of the CCD type solid-state imaging device (see, for example, Patent Document 1).

When imaging weak fluorescence with such a fluorescence observation device, the aperture provided in the light source is fully opened to amplify the sensitivity of the charge amplification type solid-state imaging device with variable sensitivity, and this charge amplification type solid-state imaging A fluorescence image was acquired by automatically gain-controlling the sensitivity of the element.
JP 2001-29313 A (page 3-5, FIG. 1-6)

  As described above, according to the conventional fluorescence observation apparatus, it is possible to capture weak autofluorescence by fully opening the light source aperture, but even if the autofluorescence is very weak, for example, a living body that is a subject. When it is very close to the tissue, the intensity of the fluorescence incident on the charge amplification type solid-state imaging device increases, and there is a possibility that the screen may be saturated (halation) if the light source diaphragm is fully opened. As described above, in the conventional fluorescence observation apparatus, it may be difficult to perform an appropriate dimming operation depending on the use situation, and in that case, it is difficult to obtain an appropriate observation image.

  The present invention has been made in view of the above circumstances, and provides an endoscope apparatus capable of easily obtaining an observation image in an appropriate dimming state for a subject whose light intensity varies greatly. It is aimed.

  A first endoscope apparatus according to the present invention is provided with an endoscope having an imaging element that is supplied with a pulse-like signal and whose sensitivity can be changed by amplifying a generated charge, and for irradiating a subject with light. A light source, a diaphragm for adjusting the amount of light applied to the subject, a photometric circuit that performs photometry of an output signal from the image sensor, and a charge amplification of the image sensor based on a photometric result of the photometric circuit A sensitivity control circuit that controls the sensitivity of the image sensor by controlling the rate, and the pulse signal for changing the sensitivity of the image sensor based on the control of the sensitivity control circuit to the image sensor And a drive circuit that calculates the sensitivity amplification factor of the image sensor based on the voltage value of the pulse-like signal, and the luminance signal from the photometry circuit is relatively reduced according to the increase or decrease of the sensitivity amplification factor. Correct to increase A photometric correction circuit for generating a positive luminance signal value, characterized in that anda aperture control circuit for controlling the iris in response to the corrected luminance signal value generated by the photometry correction circuit.

  According to the second endoscope apparatus of the present invention, the incident intensity to the image sensor is relatively small in accordance with the incident intensity to the image sensor, the sensitivity gain is increased, and the corrected luminance signal value is In the case of a decrease, control is performed to open the diaphragm according to the corrected luminance signal value, and after the diaphragm is fully opened, the sensitivity control circuit is controlled while maintaining the fully opened state. Controlling the aperture control circuit when the incident intensity to the image sensor is relatively large and the sensitivity gain is decreased to 1 time compared with the first dimming control mode for performing light control. The incident light intensity to the image sensor is relatively larger than that in the second dimming control mode in which the dimming control is performed and the first dimming control mode, and the second dimming control mode. The incident intensity to the image sensor is relatively When Sai is characterized by having a third dimming control mode for performing dimming control by controlling any of the sensitivity control circuit and the aperture control circuit.

  According to the present invention, it is possible to observe a subject image in which the intensity of light greatly fluctuates in an appropriate dimming state, the responsiveness of dimming control in the special light mode is improved, and the incident light is incident on the solid-state image sensor. Even if the intensity varies greatly, saturation of the image is prevented, and an image with appropriate brightness and high image quality can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
1 to 13 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing a schematic configuration of an endoscope apparatus, and FIG. 2 is a diagram of a charge amplification type solid-state imaging device (hereinafter referred to as a CCD). Block diagram, FIG. 3 is a timing chart of the sensitivity control pulse φCMD and horizontal transfer pulses φS1, φS2, FIG. 4 is a graph showing the relationship between the voltage applied to the charge amplifier and the sensitivity amplification factor regarding the CCD sensitivity, and FIG. FIG. 6 is a block diagram showing the configuration of the photometry circuit in FIG. 1, FIG. 7 is a block diagram showing the configuration of the sensitivity control circuit in FIG. 1, and FIG. 8 is a block diagram showing the configuration of the photometry correction circuit in FIG. 9 is a plan view showing the configuration of the rotary filter, FIG. 10 is a graph showing the CCD sensitivity characteristic (monitor output signal), FIG. 11 is a graph showing the CCD sensitivity characteristic (S / N characteristic), and FIG. Fluorescence observation) Graph illustrating the spectral characteristic of that light source device, FIG. 13 is a graph showing the spectral characteristics of the fluorescence and the reflected light in the special light observation (fluorescence observation).

(Constitution)
As shown in FIG. 1, the endoscope apparatus 1 according to the first embodiment includes an electronic endoscope (hereinafter abbreviated as an endoscope) 2, a processor 3, and a monitor 6. .

The endoscope 2 includes a CCD 19 in the endoscope distal end portion 15.
The endoscope 2 is detachably connected to the processor 3. Further, the processor 3 includes a signal processing device 4 and a light source device 5. Note that the light source device may be provided separately from the processor.

  The monitor 6 is connected to the processor 3 and displays a video signal image-processed by the processor 3.

Next, the endoscope 2 will be described in detail.
The endoscope 2 has an elongated insertion portion 11 to be inserted into a patient body cavity.
Here, the insertion portion 11 is composed of a flexible portion in the case of the digestive tract, bronchi, head and neck (for pharynx) and bladder, and is composed of a rigid portion in the case of the abdominal cavity, chest cavity and uterus. .

  Inside the insertion portion 11, a light guide 12, a CCD drive signal line 13, and a CCD output signal line 14 are disposed.

  The distal end portion 15 of the insertion portion 11 is provided with a distal end side of the light guide 12, an illumination lens 16, an objective lens 17, an excitation light cut filter 18, and a CCD 19.

  The light guide 12 guides illumination light from the light source device 5 provided in the processor 3 to the distal end portion 15 of the insertion portion 11.

  The illumination lens 16 is mounted on the distal end portion 15 of the insertion portion 11 and is disposed on the distal end surface side of the light guide 12.

  The illumination light guided from the light source device 5 by the light guide 12 is irradiated to the subject via the illumination lens 16.

The objective lens 17 forms an image of light from the subject.
The excitation light cut filter 18 is mounted on the front surface of the CCD 19 and transmits only a specific wavelength band. In the present embodiment, the excitation light cut filter 18 has a spectral characteristic that transmits autofluorescence (wavelength of approximately 500 nm or more) generated from a living tissue and does not transmit excitation light (approximately 470 nm or less).

  Reflected light and autofluorescence from the subject are imaged on the light receiving surface of the CCD 19 via the objective lens 17 and the excitation light cut filter 18.

  The CCD 19 is an image sensor provided at the distal end portion 15 of the insertion portion 11 and disposed at the imaging position of the objective lens 17. In FIG. 1, it is arranged in a direct view, but it can be arranged in a perspective or side view.

  The CCD 19 is connected to a CCD drive circuit 31 of the signal processing device 4 in the processor 3 through a plurality of drive signal lines 13. The CCD 19 performs electronic shutter control, signal charge accumulation, sensitivity control, and readout by the drive signal generated by the CCD drive circuit 31.

  The subject image formed on the light receiving surface of the CCD 19 by the objective lens 17 and the excitation light cut filter 18 is transferred after photoelectric conversion at each pixel of the CCD 19 and output from the output amplifier. The output signal from the CCD 19 is supplied to the analog processing circuit 33 of the signal processing means 4 in the processor 3 via a plurality of CCD output signal lines 14.

  The endoscope 2 has a storage device 20 mounted on the proximal end side. The storage device 20 includes a CPU 21 and a memory 22.

  The memory 22 as the storage means uses, for example, a nonvolatile EEPROM or the like, and stores data of sensitivity amplification factor characteristics of the CCD 19.

  The CPU 21 controls data reading and writing to the memory 22 and controls data transmission / reception (communication) with the processor 3.

  The memory 22 stores the following data related to the endoscope in addition to the sensitivity amplification factor characteristic data of the CCD 19.

  As stored data in this case, for example, endoscope model (type) name, endoscope serial number, white balance setting value {for normal light, special light (multiple)}, information on the forceps channel of the endoscope, There are endoscope outer diameter data, endoscope insertion diameter data, and the like.

  In this embodiment, the signal processing device 4 includes a CPU 30, a CCD drive circuit 31, a sensitivity control circuit 32, an analog processing circuit 33, an analog / digital converter (hereinafter referred to as an A / D converter) 34, Digital processing circuit 35, photometry circuit 36, photometry correction circuit 37, selector 40, synchronization memories 41, 42, 43, matrix circuit 44, digital / analog converter (hereinafter referred to as D / A converter). 45, 46, 47 and a 75Ω driver 48.

  The light source device 5 includes a lamp 50, a diaphragm 51, a diaphragm control circuit 52, a rotation filter 53, a motor 54, a condenser lens 55, a rotation filter switching mechanism 56, a rotation filter control circuit 57, and a mode switching. A switch 58 and a brightness control switch 59 are provided.

  When the endoscope 2 is connected to the processor 3, the CPU 30 performs reading control of various data stored in the memory 22 via the CPU 21. In this case, various data stored in the memory 22 is output to the CPU 30 via the CPU 21, and various data is read out by the CPU 30.

  Further, the CPU 30 outputs the sensitivity amplification factor characteristic data of the CCD 19 acquired from the memory 22 to the CCD drive circuit 31.

  Further, the CPU 30 displays the endoscope model name, serial number. And the white balance set value and the like are output to the digital processing circuit 35.

Next, the CCD 19 will be described in detail.
In this embodiment, as the CCD 19, for example, U.S. Pat. S. PAT. No. No. 5,337,340 “Charge Multiplying Detector (CMD) suitable for small pixel CCD image sensors” is used, and a solid-state imaging device with variable sensitivity using the impact ionization phenomenon is used.

  The CCD 19 is provided with a charge amplifying section between the horizontal transfer path in the CCD and the output amplifier or for each pixel. By applying a high electric field pulse from the processor to the charge amplifying section, the signal charge is changed to a strong electric field. Energy is obtained from the light and collides with electrons in the valence band, and signal charges (secondary electrons) are newly generated by impact ionization.

  For example, when the avalanche effect is used, secondary electrons are generated in a chain reaction by application of a pulse. However, when impact ionization is used, a set of electrons is applied by applying a relatively low voltage pulse to the avalanche effect. -Only hole pairs are generated.

  In this CCD 19, when the charge amplification section is provided in front of the output amplifier, it is possible to arbitrarily amplify the number of signal charges by controlling the voltage value (amplitude) of the pulse to be applied or the number of pulses.

  On the other hand, when a charge amplifying unit is provided for each pixel, it is possible to arbitrarily amplify the number of signal charges by controlling the voltage value (amplitude) of the pulse to be applied or the number of pulses.

  In this embodiment, as the CCD 19, as shown in FIG. 2, an FFT (Full Frame Transfer) type monochrome CCD in which a charge amplifier is mounted between the horizontal transfer path and the output amplifier is used.

  The CCD 19 includes an image area 60 of a light receiving unit, an OB unit (Optical Black) 61, a horizontal transfer path 62, a dummy 63, a charge amplification unit 64, and an output amplifier unit 65. Further, the charge amplifying unit 64 is configured with the number of cells substantially the same as or about twice the number of cells of the horizontal transfer path 62.

  The CCD 19 may be an FT (Frame Transfer) type provided with a charge storage unit.

  The signal charges generated in each pixel of the image area 60 are transferred to the horizontal transfer path 62 for each horizontal line by the vertical transfer pulses ΦP1 and ΦP2, and the dummy 63 and the charges are transferred from the horizontal transfer path 62 by the horizontal transfer pulses ΦS1 and ΦS2. It is transferred to the amplifying unit 64. Then, by applying a sensitivity control pulse φCMD to each cell of the charge amplifying unit 64 composed of a plurality of cells, charges are sequentially amplified one step at a time while being transferred to each cell, and sequentially transferred to the output amplifier unit 65. Is done. The output amplifier unit 65 converts the charge from the charge amplification unit 64 into a voltage and outputs the voltage.

  As shown in FIG. 3, the phases of the sensitivity control pulse φCMD and the horizontal transfer pulses φS1 and φS2 rise before φS1 rises and fall before φS1 falls.

  The sensitivity amplification factor obtained by the charge amplifier 64 is variable by changing the magnitude of the voltage value (amplitude) of the sensitivity control pulse ΦCMD from the CCD drive circuit 31 to the charge amplifier 64. In the charge amplifying unit 65, amplification is performed one stage at each cell. As shown in FIG. 4, the sensitivity amplification factor obtained by the charge amplifying unit 64 has characteristics in which charge amplification starts when the applied voltage exceeds a certain threshold value Vth and the sensitivity is exponentially amplified.

  When the sensitivity control pulse ΦCMD is 0 (V) to the threshold value Vth, the signal charge is not transferred but only transferred by the charge amplifier 64. Further, the threshold value at which charge amplification starts and the steepness of the sensitivity amplification factor with respect to the applied voltage depend on the CCD parameters and are variable in design.

  FIG. 5 is a timing chart of the drive signal and output signal of the CCD 19 in the normal light mode and special light (fluorescence observation) mode. FIG. 5A shows the operation of the rotary filter 53 in the normal light mode, and FIG. ) Is vertical transfer pulses φP1 and φP2 in the normal light mode, FIG. 5C is horizontal transfer pulses φS1 and φS2 in the normal light mode, FIG. 5D is a sensitivity control pulse φCMD in the normal light mode, and FIG. (E) is an output signal from the CCD 19 in the normal light mode, FIG. 5 (f) is an operation of the rotary filter 53 in the special light mode, and FIG. 5 (g) is a vertical transfer pulse φP1, φP2 in the special light mode. FIG. 5H shows the horizontal transfer pulses ΦS1 and ΦS2 in the special light mode, FIG. 5I shows the sensitivity control pulse φCMD in the special light mode, and FIG. 5J shows the output signal from the CCD 19 in the special light mode. Shows each

  As shown in FIG. 5, the CCD drive circuit 31 receives vertical transfer pulses φP1 and φP2, horizontal transfer pulses φS1 and φS2, and an electronic shutter pulse φOFD (not shown) as drive signals to the CCD 19 in the normal light mode and special light (fluorescence observation) mode. Output.

  The CCD drive circuit 31 does not output the sensitivity control pulse φCMD supplied to the CCD 19 in the normal light mode, and outputs the sensitivity control pulse φCMD to the CCD 19 in the special light (fluorescence observation) mode. Note that the sensitivity control pulse φCMD is output in the normal light mode, but the voltage value may be set to a threshold value Vth or less.

  In the normal light mode, the CCD 19 can accumulate as signal charges by photoelectrically converting light incident on the light receiving surface of the CCD 19 during the R, G, and B exposure periods shown in FIG. Yes.

  In the light shielding period shown in FIG. 5A, the CCD drive circuit 31 outputs vertical transfer pulses φP1 and φP2 shown in FIG. 5B and horizontal transfer pulses φS1 and φS2 shown in FIG. Reading of the CCD 19 is performed, and an output signal shown in FIG.

  Here, as described above, the CCD drive circuit 31 does not output the sensitivity control pulse φCMD in the normal light mode.

  Thus, in the normal light mode, the charge amplification unit 64 does not perform charge amplification, and the sensitivity amplification factor is 1 (no amplification).

  In the special light mode, the CCD 19 can accumulate as signal charges by photoelectrically converting light incident on the light receiving surface of the CCD 19 during the exposure period of the three wavelengths Ex1, Ex2, and Ex3 shown in FIG. It has become.

  In the light shielding period shown in FIG. 5F, that is, the readout period of the CCD 19, the CCD drive circuit 31 performs the vertical transfer pulses φP1 and φP2 shown in FIG. 5G and the horizontal transfer pulses φS1 and φS2 shown in FIG. The sensitivity control pulse φCMD shown in FIG. 5 (i) is output, whereby the CCD 19 is read, and an output signal is obtained from the CCD 19 shown in FIG. 5 (j).

  Here, the CCD drive circuit 31 varies the voltage value (amplitude) of the sensitivity control pulse φCMD shown in FIG. 5I based on the data supplied from the sensitivity control circuit 32. Then, the CCD drive circuit 31 outputs the sensitivity control pulse φCMD shown in FIG. 5 (i) to the CCD 19 in a phase relationship synchronized with the horizontal transfer pulses ΦS1 and ΦS2 shown in FIG. 5 (h).

  Thus, in the special light mode, the CCD drive circuit 31 controls the CCD 19 so as to obtain a desired sensitivity amplification factor by changing the voltage value (amplitude) of the sensitivity control pulse ΦCMD applied to the charge amplifier 64. .

  In this way, charges are accumulated in each pixel of the image area 60 of the CCD 19 during the exposure period, and a drive signal is output to the CCD 19 during the light-shielding period. The data is transferred to the horizontal transfer path 62, and sequentially transferred to the dummy 63, the charge amplification unit 64, and the output amplifier unit 65 by the horizontal transfer pulses ΦS1 and ΦS2.

  The exposure period of the CCD 19 differs depending on the type of special light mode. In this embodiment, the exposure time (accumulation time) in the fluorescence observation mode is about three times that in the normal light mode.

  The driving and reading timing of the CCD 19 is switched according to the observation mode (mode switching signal) selected from the mode switch 58.

  A counter value related to the voltage value (amplitude) of the sensitivity control pulse φCMD output to the charge amplifier 64 is input from the sensitivity control circuit 32 to the CCD drive circuit 31. In addition, the sensitivity amplification factor characteristic (relationship between applied voltage and sensitivity amplification factor) of the charge amplification unit 64 of the CCD 19 is input from the memory 22 of the storage device 20 via the CPU 21 and the CPU 30.

  The correspondence relationship between the counter value and the voltage applied to the charge amplifying unit 64 is such that the voltage Vth shown in FIG. 4 when the counter value is minimum and the voltage Vmax shown in FIG. 4 when the counter value is maximum. The sensitivity control pulse φCMD corresponding to the counter value set from the sensitivity control circuit 32 is output to the charge amplifying unit 64 in the range of Vth to Vmax. Since the sensitivity amplification factor characteristic varies depending on the CCD or the variation of the drive signal line, the sensitivity control circuit 32 matches the minimum value Vth and the maximum value Vmax of the sensitivity control pulse φCMD with the minimum value and the maximum value of the counter value. Correction means.

  The relationship between the voltage value of the sensitivity control pulse ΦCMD of the charge amplifier 64 shown in FIG. 2 and the sensitivity amplification factor is expressed by the following equation.

M (V) = C · Exp {α (V−Vth)} (1)
However, M (V) is a sensitivity amplification factor when the voltage value (amplitude) of ΦCMD is V (v), Vth is a threshold voltage at which charge amplification is started, and C, α, and Vth are constants specific to the device.

  For example, when the applied voltage value to the charge amplifying unit 64 is V (V), if the counter value changes by ± 1, if the voltage value corresponding to the counter value change of 1 is ΔV (V), the applied voltage V ′ = V. Since ± ΔV (V), the sensitivity amplification factor at that time is as follows.

M (V ′) = C · Exp {α (V′−Vth)}
= C · Exp {α (V ± ΔV−Vth)} (2)
Further, the change rate of the sensitivity amplification factor at that time is as follows.
M (V ') / M (V)
= C · Exp {α (V ± ΔV−Vth)} / C · Exp {α (V−Vth)}
= Exp (± α · ΔV) (3)
Using such a relational expression, the CCD drive circuit 31 calculates the sensitivity amplification factor of the charge amplifier 64 from the voltage value of the sensitivity control pulse φCMD, and outputs the sensitivity amplification factor to the photometry correction circuit 37.

  The analog processing circuit 33 is provided with a preamplifier for amplifying the CCD output signal from the CCD 19 and a CDS circuit for performing correlated double sampling to reduce CCD noise. The signal subjected to CDS processing by the analog processing circuit 33 is output to the A / D converter 34 and converted into a digital signal. The output of the A / D converter 34 is output to the digital processing circuit 35.

  The digital processing circuit 35 performs signal processing such as clamp processing, white balance processing, color conversion processing, electronic zoom processing, gamma conversion processing, and image enhancement processing on the video signal input from the A / D converter 34. After that, the three wavelengths are synchronized and output to the selector 40.

  In the digital processing circuit 35, the white balance processing can be set to different values for the normal light and the special light observation modes in accordance with the mode switching signal from the mode switch 58. As the setting value corresponding to each observation mode, the setting value stored in the memory 22 is input to the digital processing circuit 35 via the CPU 30.

  The selector 40 separates the normal light mode or special light mode time-series images output from the digital processing circuit 35 and outputs the separated images to the three-axis synchronization memories 41, 42, and 43.

  The synchronization memories 41, 42, and 43 store images in the normal light mode or the special light mode, and simultaneously read out each other to synchronize the frame sequential images and output them to the matrix circuit 44.

  The matrix circuit 44 performs different color conversion processing in the normal light mode and the special light mode in accordance with the mode switching signal from the mode switch 58.

  In the case of the special light mode, the matrix circuit 44 multiplies each image from the synchronization memories 41, 42, and 43 for each selected special light mode by a predetermined matrix coefficient to construct a composite image. The matrix circuit 44 outputs the constructed image to the D / A converters 45, 46 and 47.

  In the normal light mode, the matrix circuit 44 outputs the images to the D / A converters 45, 46, and 47 without performing color conversion processing on the images from the synchronization memories 41, 42, and 43.

  The D / A converters 45, 46 and 47 convert each image from the matrix circuit 44 into an analog video signal and output it.

  The 75Ω driver 48 outputs analog video signals input from the D / A converters 45, 46, and 47 in the normal light mode and special light mode to the monitor 6 and peripheral devices such as a recording device (not shown).

  The photometry circuit 36 has a sub-sampling circuit 71, an integration circuit 72, and a luminance signal calculation circuit 73 as shown in FIG.

  The sub-sampling circuit 71 thins out the video signal corresponding to each wavelength of each observation mode input from the A / D converter 34 and outputs it to the integration circuit 72. In the present embodiment, the subsampling circuit 71 performs subsampling, so that the circuit scale of the subsequent integration circuit 72 can be reduced.

  The integrating circuit 72 integrates the normal light mode or special light mode image input from the sub-sampling circuit 71 for each field, and calculates an integrated value for each field. The integration circuit 72 outputs the integration result to the luminance signal calculation circuit 73.

  The luminance signal calculation circuit 73 calculates a luminance signal based on the integration value for each field of each wavelength calculated by the integration circuit 72.

  The calculation of the luminance signal by the luminance signal calculation circuit 73 is different for each observation mode based on the mode switching signal of the mode switch 58.

  In the normal light mode, the luminance signal calculation circuit 73 calculates the luminance signal by adding the integrated values of the R, G, and B fields after being multiplied by 0.3, 0.59, and 0.11, respectively. To do.

  In the special light mode, the luminance signal calculation circuit 73 multiplies the integral value of each field by a predetermined coefficient and then adds the result to calculate a luminance signal.

  The luminance signal calculated for each observation mode by the luminance signal calculation circuit 73 is output to the sensitivity control circuit 32 and the photometric correction circuit 37.

  As shown in FIG. 7, the sensitivity control circuit 32 includes a comparison circuit 81, a lookup table circuit (LUT circuit) 82, an up / down counter 83, and a decoding circuit 84.

  The LUT circuit 82 converts the level selected by the operator with the brightness control switch 59 into a target value and outputs it to the comparison circuit 81.

  More specifically, the LUT circuit 82 includes a plurality of LUTs (Look Up Tables) corresponding to the normal light mode and the special light mode, and the normal light mode or the plurality of special light modes selected from the mode switch 58. The LUT is switched and selected in accordance with the switching signal, and the level selected by the brightness control switch 59 in the LUT selected by switching is converted into a target value and output to the comparison circuit 81.

  The comparison circuit 81 compares the luminance signal of the normal light mode and the special light mode input from the photometry circuit 36 with the target value of the monitor brightness input from the LUT circuit 82, and outputs the comparison result to the up / down counter 83. To do. The comparison circuit 81 has a function of increasing or decreasing the count value in order to improve the response of the sensitivity amplification factor when the difference between the luminance signal and the target value is large.

  The up / down counter 83 increases or decreases the counter value based on the comparison result between the luminance signal input from the comparison circuit 81 and the brightness target value (C ′ = C ± 1). The up / down counter 83 outputs the counter value to the CCD drive circuit 31 and the decode circuit 84.

  The up / down counter 83 stops the counter output when a stop signal is input from the decode circuit 84. The up / down counter 83 stops the counter output when the mode switching signal from the mode switch 58 is in the normal light mode. That is, the sensitivity control circuit 32 operates only in the special light mode.

  The decode circuit 84 determines an overflow or underflow from the counter value input from the up / down counter 83 and outputs a stop signal to the up / down counter 83 when an overflow or underflow occurs.

  In this case, the sensitivity gain characteristics data of the CCD 19 stored in the memory 22 of the storage device 20 is an area from the threshold Vth at which charge amplification is started to Vmax where the sensitivity gain is the maximum value as shown in FIG. May be divided into a number corresponding to the total number of counters of the up / down counter 83 and the voltage value (amplitude) and the sensitivity amplification factor may be stored as a set. Further, the relationship between the applied voltage and the sensitivity amplification factor M (V) is that M (V) = C · Exp {α (V−Vth)}, so that the stored data is changed to sensitivity amplification factors such as C, α, Vth, and Vmax. Related parameters may be used.

  As shown in FIG. 8, the photometry correction circuit 37 is based on the luminance signal in the normal light mode and the special light mode input from the photometry circuit 36 and the sensitivity amplification factor of the charge amplifier 64 input from the CCD drive circuit 31. An operation for dividing the luminance signal by the sensitivity gain is performed. Then, the photometric correction circuit 37 outputs the calculation result to the aperture control circuit 52.

  The purpose of the photometric correction circuit 37 is that the input luminance signal is calculated based on the CCD output value obtained by the sensitivity amplification by the charge amplifying unit 64. Therefore, the sensitivity amplification factor 1 is obtained by dividing the luminance signal by the sensitivity amplification factor. It is to obtain a corrected luminance signal equivalent to double (no amplification).

  The mode changeover switch 58 is a switch that allows the operator to arbitrarily select any observation mode from normal light observation or multiple special light observations (fluorescence observation, narrowband light observation, infrared light observation, etc.). is there.

  Note that the installation place of the mode switch 58 may be the processor 3, the keyboard, the foot switch, the endoscope 2, or both.

  The mode switching signal (observation mode) selected by the mode switching switch 58 includes a rotation filter switching mechanism 56, a rotation filter control circuit 57, a photometry circuit 36, a CCD drive circuit 31, a digital processing circuit 35, a matrix circuit 44, and sensitivity control. It is output to the circuit 32.

  The brightness control switch 59 is a switch that allows the operator to arbitrarily select a target brightness value of the monitor screen from a plurality of stages.

The installation location of the brightness control switch 59 is the front panel of the processor 3.
A signal based on the operation of the brightness control switch 59 is output to the sensitivity control circuit 32 and the aperture control circuit 52.

Hereinafter, the light source device 5 will be described in detail.
The lamp 50 of the light source device 5 includes a xenon lamp, a halogen lamp, an LED, an LD (semiconductor laser), and the like, and generates illumination light.

  The condensing lens 55 condenses the luminous flux of the illumination light guided from the lamp 50 through the diaphragm 51 and the rotary filter 53 on the rear end surface of the light guide 12.

  The diaphragm 51 and the rotary filter 53 are inserted between the lamp 50 and the condenser lens 55. The rotary filter 53 is rotatably connected to the rotary shaft of the motor 54 and is controlled to rotate at a predetermined speed by the rotary filter control circuit 57.

  The rotation filter control circuit 57 can control the rotation speed of the rotation filter 53 (motor 54) to a predetermined rotation speed by a mode switching signal from the mode switch 58. The rotation filter control circuit 57 changes the rotation speed of the rotation filter 53 depending on the observation mode. The rotation filter control circuit 57 sets the rotation speed in the special light observation mode to a half rotation speed with respect to the normal light mode.

  The aperture control circuit 52 receives the luminance signal from the photometry correction circuit 37 and compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59. From this comparison result, the diaphragm control circuit 52 controls the amount of illumination light to the rear end face of the light guide 12 by controlling the opening / closing operation of the diaphragm 51 inserted on the illumination optical path of the lamp 50 and the rotary filter 53.

  As shown in FIG. 9, the rotary filter 53 has a double structure in which two sets of filter sets 66 and 67 are provided on the inner peripheral portion and the outer peripheral portion.

  The rotary filter switching mechanism 56 includes a first filter set 66 on the inner peripheral side of the rotary filter 53 and a second filter set 67 on the outer peripheral side on the illumination optical axis connecting the lamp 50 and the rear end surface of the light guide 12. This is a mechanism for selectively moving any one of the rotary filters 53. Further, the rotation filter switching mechanism 56 may or may not move the rotation filter 53 depending on the type of special light observation.

  In the normal light mode, the rotary filter switching mechanism 56 arranges the inner peripheral filter set 66 on the illumination optical axis.

  In the special light mode, the rotary filter switching mechanism 56 arranges the outer peripheral filter set 67 on the illumination optical axis.

  As shown in FIG. 9, the first filter set 66 in the inner peripheral portion of the rotary filter 53 is three filters for R, G, and B for the normal light mode, and each of red (R) and green (G ), Filters 66R, 66G, 66B having spectral characteristics that transmit the blue (B) wavelength band.

  The second filter set 67 in the outer peripheral portion is provided with three filters 91, 92, 93 having spectral characteristics for special light mode (fluorescence observation), Ex1, Ex2, and Ex3.

  For example, in the present embodiment, the Ex1 filter 91 is an excitation light filter that transmits a 390 to 470 nm region.

  The Ex2 filter 92 is a reflected light filter having a spectral characteristic of a narrow band with a center wavelength of about 550 nm, a half width of about 30 nm, and a transmittance of about several percent.

  The Ex3 filter 93 is a reflected light filter having a spectral characteristic of a narrow band with a center wavelength of about 600 nm, a half width of about 30 nm, and a transmittance of about several percent.

  In the special light mode, the illumination light emitted from the illumination lens 16 of the endoscope 2 has a spectral characteristic as shown in FIG. 12, for example.

  The filters 66R, 66G, and 66B correspond to the exposure period of the CCD 19, and the light shielding portion provided between the filters 66R, 66G, and 66B corresponds to the light shielding period (readout period) of the CCD 19. The same applies to the second filter set 67.

  Each size of the second filter set 67 is set to about 1.5 times that of the first filter set 66 in this embodiment. The rotation speed of the rotary filter 53 is set to ½ of the normal light mode in the fluorescence observation mode. The exposure time (accumulation time) in the special light mode is set to three times that in the normal light mode. Since autofluorescence is very weak light, the exposure time is lengthened.

  In FIG. 9, the normal light filters 66R, 66G, and 66B are provided on the inner periphery and the special light filters 91, 92, and 93 are provided on the outer periphery. However, the arrangement may be reversed.

  The filter aperture ratio of the second filter set 67 may be the same as that of normal light, or the aperture ratio may be changed for each wavelength.

(Function)
A method of using the endoscope apparatus 1 according to the first embodiment will be described below.

  In starting the endoscopy, the operator connects the endoscope 2 of a type corresponding to the observation site and the type of observation from the plurality of types of endoscopes to the processor 3.

  As a result, the CPU 30 of the processor 3 reads various data related to the endoscope 2 stored in the memory 22 via the CPU 21 of the endoscope 2. Sensitivity gain characteristic (relationship between voltage value and sensitivity gain) data of the CCD 19 stored in the memory 22 is output to the CCD drive circuit 31 via the CPU 30.

Next, the operation in the normal light mode and the special light mode (fluorescence observation) will be described.
The surgeon inserts the insertion portion 10 of the endoscope 2 into the patient's body cavity (bronchi, esophagus, stomach, large intestine, head and neck, abdominal cavity, chest cavity, bladder, uterus, etc.) and performs normal light observation.

  When performing normal light observation (normal light mode), the rotary filter switching mechanism 56 arranges the first filter set 66 on the illumination optical path, and the sensitivity amplification factor of the CCD 19 is set to 1 time (no amplification). . In this state, the illumination light emitted from the lamp 50 passes through the first filter set 66, so that the R (red), G (green), and B (blue) sequential illumination lights are internally viewed in the living tissue. The light is irradiated in time series from the illumination lens 16 via the light guide 12 of the mirror 2.

  In the photometry circuit 36, a luminance signal displayed on the monitor screen is calculated and output to the sensitivity control circuit 32 and the photometry correction circuit 37. In the normal light mode, the counter output from the sensitivity control circuit 32 to the CCD drive circuit 31 is stopped. Therefore, the sensitivity control pulse φCMD is not output from the CCD drive circuit 31 to the CCD 19, and the CCD 19 has a sensitivity amplification factor of 1.

  Therefore, data with a sensitivity amplification factor of 1 (no amplification) is output from the CCD drive circuit 31 to the photometric correction circuit 37. In the photometry correction circuit 37, the luminance signal from the photometry circuit 36 and the sensitivity amplification factor from the CCD drive circuit 31 are divided, and an output from the photometry circuit 36 is sent to the aperture control circuit 52 so that the sensitivity amplification factor is 1. The same value as the value is output.

  The diaphragm control circuit 52 compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59, and performs opening / closing control of the diaphragm 51 according to the comparison result (magnitude relationship). When the luminance signal is brighter than the target value, the diaphragm 51 is operated in the closing direction (the irradiation intensity on the rear end face of the light guide 12 is reduced), while when the monitor screen is darker than the target value, the diaphragm 51 is opened. The brightness of the monitor 6 is maintained at the operator's set value by operating in the direction (the irradiation intensity to the rear end surface of the light guide 12 is increased) and changing the irradiation intensity of the irradiation light to the living tissue. Thus, an automatic light control operation (automatic gain control by aperture opening / closing control of the light source device) by the control of the aperture 51 is performed.

  The reflected light of R, G, B from the living tissue is sequentially incident on the light receiving surface (image area 60) of the CCD 19, and the output signal of the CCD 19 corresponding to the reflected light of R, G, B is input to the signal processing device 4. Various signal processing is performed by the analog processing circuit 33 and the digital processing circuit 35, and peripheral devices such as the monitor 6 and the recording device via the selector 40, the synchronization memories 41, 42, 43, the matrix circuit 44, and the 75Ω driver 48. Is output. As a result, the normal light image is displayed and recorded on the monitor 6 and peripheral devices.

  In the digital processing circuit 35, the R, G, B white balance coefficients are set values for the normal light mode stored in the memory 22. In the matrix circuit 44, the R, G, and B images are output without being subjected to color conversion processing.

  The output signal of the normal light image displayed on the monitor 6 and the S / N characteristic thereof are obtained by the broken line in FIGS.

  When performing fluorescence observation (special light mode), the surgeon selects fluorescence observation from a plurality of observation modes of the mode switch 58. In accordance with this selection instruction, the rotary filter switching mechanism 56 places the second filter set 67 of the rotary filter 53 on the illumination optical path.

  Illumination light emitted from the lamp 50 of the light source device 5 is transmitted through the second filter set 67 of the rotary filter 53. Blue light that is excitation light of the filter Ex1, generated by the filter Ex2, green illumination light of the filter Ex2, and the filter Ex3 The red illumination light is incident on the rear end surface of the light guide 12 through the condenser lens 55, and is applied to the living tissue from the illumination lens 16 provided at the distal end portion 15 of the endoscope 2, for example, as shown in FIG. Irradiation is performed in time series as illumination light having spectral characteristics (spectrum, intensity).

  The objective lens 17 receives reflected light (return light) of excitation light itself by excitation light irradiation to the living tissue and weak autofluorescence having a peak in the vicinity of approximately 520 nm emitted from the living tissue by the excitation light. The reflected light of the excitation light itself is cut by the excitation light cut filter 18, and only autofluorescence enters the light receiving surface of the CCD 19. The reflected lights of the green and red illumination lights are incident on the objective lens 17, pass through the excitation light cut filter 18, and enter the light receiving surface of the CCD 19. As a result, light having the spectral characteristics of autofluorescence and reflected light as shown in FIG.

  Fluorescent, green and red reflected light from the living tissue is sequentially incident on the CCD 19 and CCD output signals corresponding to the respective wavelengths are input to the signal processing device 4, and predetermined signal processing is performed by the analog processing circuit 33 and the digital processing circuit 35. And a fluorescent image is recorded on the monitor 6 and the recording device via the selector 40, the synchronization memories 41, 42, 43, the matrix circuit 44, and the 75Ω driver 48. In the digital processing circuit 35, the white balance coefficient is set for fluorescence observation from among a plurality stored in the memory 22 at the time of imaging fluorescence, green and red reflected light. Further, in the matrix circuit 44, for example, predetermined color conversion is performed so that the output of each wavelength is output to the G channel for fluorescence, the B channel for red reflected light, and the R channel for green reflected light.

  In the fluorescence observation, when observing a living tissue, the intensity of incident light on the CCD 19 varies with the variation of the state of the living tissue or the distance between the living tissue and the distal end of the endoscope 2, and the luminance signal of the monitor 6 is In some cases, the surgeon may not match the target value (reference value) selected by the brightness control switch 59. In that case, the following light control is performed.

  The photometry circuit 36 calculates the luminance signal of the fluorescent image constructed from the fluorescence wavelength and the reflected wavelength, and outputs the luminance signal to the sensitivity control circuit 32 and the photometry correction circuit 37. The sensitivity control circuit 32 compares the brightness signal with the brightness target value selected by the operator with the brightness control switch 59 in the comparison circuit 81, and the counter value corresponding to the comparison result is transferred from the up / down counter 83 to the CCD. Output to the drive circuit 31.

  The CCD drive circuit 31 outputs the voltage value of the sensitivity control pulse φCMD to the charge amplifier 64 as a voltage corresponding to the counter value. The sensitivity amplification factor of the CCD 19 increases or decreases in accordance with the voltage value of the sensitivity control pulse φCMD, and the CCD drive circuit 31 increases or decreases the sensitivity amplification factor so as to compensate for the fluctuation of the incident light intensity to the CCD 19. The brightness of the image is changed, and control is performed so that the luminance signal matches the brightness target value.

  The CCD drive circuit 31 calculates the sensitivity amplification factor of the charge amplification unit 64 from the voltage value of the sensitivity control pulse φCMD, and outputs the calculated sensitivity amplification factor to the photometry correction circuit 37. The photometry correction circuit 37 calculates [(brightness signal) / (sensitivity amplification factor)] based on the luminance signal from the photometry circuit 36 and the sensitivity amplification factor from the CCD drive circuit 31 to increase the sensitivity amplification factor by one. The corrected luminance signal is output to the aperture control circuit 52. The diaphragm control circuit 52 compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59, and performs opening / closing control of the diaphragm 51 according to the comparison result.

  In this case, the endoscope apparatus 2 is operated to close the diaphragm 51 when the luminance signal is brighter than the target value, and is operated to open the diaphragm 51 when the luminance signal is darker than the target value. By changing the irradiation intensity of the irradiation light on the living tissue, an automatic light control operation is performed by controlling the diaphragm 51 so that the brightness of the monitor 6 matches the target value.

  Autofluorescence is weak, and when a biological tissue is observed with fluorescence from a far point to a near point, the sensitivity amplification factor is several tens of times to obtain sufficient monitor brightness. Therefore, the corrected luminance signal becomes very small, so that the diaphragm 51 is controlled in the opening direction and is held at the fully open position. The sensitivity control circuit 32 compares the target value of the monitor brightness with the luminance signal, and increases or decreases the voltage value (amplitude) of the sensitivity control pulse φCMD from the CCD drive circuit 31 according to the comparison result, thereby increasing the sensitivity gain. The luminance signal is changed by increasing / decreasing, and control is performed so that the luminance signal matches the target brightness value. In this case, an automatic dimming operation based only on the sensitivity amplification factor of the charge amplification unit 64 of the CCD 19 (a dimming operation based on priority control based on the sensitivity amplification factor of the charge amplification unit 64) is performed.

  When the biological tissue is observed at a close-up point and fluorescence is observed, and the intensity of incident light on the CCD 19 is increased to a normal light level, sensitivity amplification for the CCD 19 becomes unnecessary. For this reason, the sensitivity amplification factor output from the CCD drive circuit 31 to the photometry correction circuit 37 is multiplied by 1. In the photometry correction circuit 37, the luminance signal and the sensitivity amplification factor are divided. The same value as the output value from the photometry circuit 36 is output to the circuit 52. The diaphragm control circuit 52 compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59, and performs opening / closing control of the diaphragm 51 according to the comparison result. When the luminance signal is brighter than the target value, the aperture control circuit 52 operates in the direction to close the aperture 51, and when the monitor screen is darker than the target value, the aperture control circuit 52 operates in the direction to open the aperture 51. In this case, an automatic dimming operation using only the aperture 51 (a dimming operation based on priority control of the aperture opening / closing operation) is performed.

  When a biological tissue is observed with fluorescence at a near point and the incident light intensity on the CCD 19 becomes relatively larger than that of normal light, a situation in which the sensitivity amplification factor is 1 to 2 times occurs and the corrected luminance signal becomes large. In the aperture control circuit 52, the brightness target value selected by the operator with the brightness control switch 59 and the corrected luminance signal are at the same level. When the incident light intensity on the CCD 19 fluctuates in the direction of increasing, the sensitivity amplification factor gradually decreases, and the diaphragm 51 also operates in the direction of gradually closing in conjunction with it. In addition, when the incident light intensity to the CCD 19 fluctuates in a decreasing direction, the sensitivity amplification factor is gradually increased in conjunction with the operation of the diaphragm 51 in a gradually opening direction. In this case, an automatic dimming operation in which the sensitivity amplification factor of the charge amplifying unit 64 and the opening / closing of the aperture 51 are simultaneously operated in conjunction with each other (a dimming operation by dimming operation by the sensitivity amplification factor and interlocking control of the aperture opening / closing operation) Is called.

  As a result, the output signal shown in the solid line in FIGS. 10 and 11 and the S / N characteristic thereof are obtained on the monitor 6. In the autofluorescence region (CCD incident light intensity in FIG. 10 and FIG. 11 is around 0.01 [au]), the sensitivity gain is 1 times by extending the exposure time and increasing the sensitivity gain of the CCD 19 with respect to the normal light mode. Output signals and S / N characteristics of 3 times or 30 times can be obtained. In the autofluorescence region, the monitor screen is dark and the S / N characteristic is very poor in the characteristics (broken line) during normal light observation. However, by increasing the sensitivity amplification factor from several times to several tens of times, the monitor screen is bright and a fluorescent image (combined image of fluorescence and reflected light) with high S / N characteristics (high image quality) can be obtained. The sensitivity amplification factor can be arbitrarily amplified by controlling the applied voltage value (amplitude).

  In fluorescence observation, for example, when the biological mucosa is irradiated with excitation light of a blue region, autofluorescence having a peak near 520 nm is obtained, and this autofluorescence intensity uses a characteristic that a lesion site is smaller than a normal site. . Also, in fluorescence observation, the site of observation is imaged by using the reflected red light as the reference light (wavelength band without the influence of blood) and the influence of blood, that is, the green reflected light that can capture the hemoglobin absorption band sensitively. The synthesized image obtained in this way excludes the influence of inflammation (blood) and enables the observation of the presence or absence of a lesion. For example, by fluorescence observation, blood vessels and inflammation are displayed in different colors from normal tissues, and adenoma and cancer sites are displayed in colors different from normal tissues and inflammation and blood vessels. As a result, fluorescence observation makes it easier to pick up tumorous lesions than normal observation.

(effect)
According to the first embodiment, in the special light mode (fluorescence observation), the dimming operation is performed by appropriately interlocking the sensitivity amplification factor of the sensitivity variable CCD and the aperture of the light source. Responsiveness of the operation is improved, and a fluorescent image that is a composite image of fluorescence and reflected light prevents a saturation of the image even if the incident intensity to the CCD 17 fluctuates greatly, thereby providing a more appropriate brightness and high quality image. Be able to get.

(Second Embodiment)
14 and 15 relate to the second embodiment of the present invention, FIG. 14 is a block diagram showing a schematic configuration of the endoscope apparatus, and FIG. 15 is a block diagram showing a configuration of the sensitivity control circuit of FIG. .

  In the description of the second embodiment using FIG. 14 and FIG. 15, the same components as those in the first embodiment shown in FIG. 1 to FIG.

(Constitution)
In the first embodiment shown in FIGS. 1 to 13, the sensitivity gain of the variable sensitivity CCD and the aperture of the light source are linked during the dimming operation in the special light mode. In the endoscope apparatus 101 of the second embodiment shown, a dimming switching circuit 137 is provided, and the dimming operation is performed either by changing the sensitivity gain of the CCD 19 or by opening / closing the aperture.

  As shown in FIG. 14, the endoscope apparatus 101 according to the second embodiment includes an endoscope 2, a processor 103, and a monitor 6.

  The endoscope 2 is detachably connected to the processor 103. The processor 103 includes a signal processing device 104 and a light source device 105. Note that the light source device 105 may be provided separately from the processor 103.

  The monitor 6 is connected to the processor 103 and displays a video signal image-processed by the processor 103.

  In the present embodiment, the signal processing device 104 includes a CPU 30, a CCD drive circuit 131, a sensitivity control circuit 132, an analog processing circuit 33, an A / D converter 34, a digital processing circuit 35, and a photometry circuit 136. A dimming switching circuit 137, a selector 40, synchronization memories 41, 42, 43, a matrix circuit 44, D / A converters 45, 46, 47, and a 75Ω driver 48.

  The light source device 105 includes a lamp 50, a diaphragm 51, a diaphragm control circuit 152, a rotation filter 53, a motor 54, a condenser lens 55, a rotation filter switching mechanism 56, a rotation filter control circuit 57, a mode. A changeover switch 58 and a brightness control switch 59 are provided.

  In the second embodiment, the operation (exposure, light shielding) of the rotary filter 53 in the normal light mode and special light (fluorescence observation) mode, the timing of the drive signal supplied to the CCD 19 by the CCD drive circuit 131, and the The timing of the output signal is the same as that of the first embodiment shown in FIG.

  Counter values Cmin to Cmax are input to the CCD drive circuit 131 from a sensitivity control circuit 132 described later.

  The counter values Cmin to Cmax are related to the voltage value of the sensitivity control pulse φCMD output from the sensitivity control circuit 132 to the charge amplification unit 64 (see FIG. 2) of the CCD 19.

  Further, the CCD drive circuit 131 has a sensitivity amplification factor characteristic (relationship between applied voltage and sensitivity amplification factor) of the charge amplification unit 64 (see FIG. 2) of the CCD 19 via the CPU 21 and the CPU 30 from the memory 22 of the storage device 20. Data is entered.

  The correspondence between the counter values Cmin to Cmax and the applied voltage values Vth to Vmax (see FIG. 4) to the charge amplifier 64 (see FIG. 4) is the voltage Vth when the counter value is the minimum Cmin, and the counter value is the maximum Cmax. In this case, the voltage Vmax is set.

  Then, the CCD drive circuit 131 outputs a sensitivity control pulse φCMD corresponding to the counter values Cmin to Cmax to the charge amplification unit 64 (see FIG. 2) of the CCD 19 in the range of Vth to Vmax.

  Since the sensitivity amplification factor characteristic of the CCD 19 changes depending on the CCD or the variation of the drive signal line, the CCD drive circuit 131 has the minimum value Vth and the maximum value Vmax of the sensitivity control pulse φCMD voltage as the minimum Cmin of the counter value. Correction means for matching the maximum Cmax is provided.

  The relationship between the voltage value of the sensitivity control pulse ΦCMD supplied to the charge amplifier 64 (see FIG. 2) and the sensitivity amplification factor of the CCD 19 is the same as in the first embodiment.

  The photometric circuit 136 differs from the first embodiment in that the luminance signal calculated for each observation mode is output to the aperture control circuit 152 in addition to the sensitivity control circuit 132.

  The sensitivity control circuit 132 includes a comparison circuit 81, an LUT circuit 82, an up / down counter 183, and a decode circuit 184 as shown in FIG.

  The up / down counter 183 increases or decreases the counter values Cmin to Cmax (C ′ = C ± 1) based on the comparison result between the luminance signal input from the comparison circuit 81 and the target brightness value. The up / down counter 183 outputs the counter value to the CCD driving circuit 131, the dimming / switching circuit 137, and the decoding circuit 184. The up / down counter 183 stops the counter output at the maximum value Cmax when a stop signal is input from the decode circuit 184. Further, the up / down counter 183 sets the counter output to the minimum value Cmin and stops the counter operation when the mode switching signal from the mode switching switch 58 becomes the normal light mode. That is, the sensitivity control circuit 132 operates only in the special light mode.

  The decode circuit 184 determines whether or not the counter value input from the up / down counter 183 has overflowed, and outputs a stop signal to the up / down counter 183 in the case of overflow.

  Here, the overflow is when the voltage value (amplitude) of the sensitivity control pulse φCMD applied from the CCD drive circuit 131 to the charge amplifier 64 (see FIG. 2) becomes the counter value Cmax corresponding to the maximum voltage Vmax. is there.

  The dimming switching circuit 137 switches and selects one of the dimming permission signal and the dimming stop signal, and inputs it to the up / down counter 183. The up / down counter 183 starts the counting operation when the dimming permission signal is input, and stops the counting operation with the counter value Cmin when the dimming stop signal is input.

  In the light source device 105, only the aperture control circuit 152 is different from the first embodiment.

  The aperture control circuit 152 receives the luminance signal from the photometry circuit 136, and compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59. Subsequently, the aperture control circuit 152 performs opening / closing control of the aperture 51 inserted on the optical path of the lamp 50 and the rotary filter 53 based on the comparison result, and controls the amount of illumination light on the rear end surface of the light guide 12. To do.

  The aperture control circuit 152 receives a dimming permission signal or a dimming stop signal from the dimming switching circuit 137.

  The diaphragm control circuit 152 starts opening / closing control of the diaphragm 51 by inputting a dimming permission signal, and fixes (holds) the opening / closing position of the diaphragm 51 to a predetermined position by inputting a dimming stop signal. Here, the predetermined position indicates an opening / closing position of the diaphragm 51 such that the intensity of incident light on the rear end face of the light guide 12 is maximized, and is an opening / closing position close to or fully open (open).

  As a result, there are two dimming methods for the endoscope apparatus 101, namely, the variable sensitivity gain of the CCD 19 and the opening / closing operation of the diaphragm 51 of the light source apparatus 105. The dimming switching circuit 137 has the two dimming modes. One of the light control methods is determined and switched.

  Counter values Cmin to Cmax indicating sensitivity gains are input from the sensitivity control circuit 132 to the dimming switching circuit 137. The dimming switching circuit 137 outputs a dimming stop signal to the sensitivity control circuit 132 when a counter value Cmin corresponding to a sensitivity amplification factor of 1 is input. The dimming switching circuit 137 outputs a dimming permission signal to the aperture control circuit 152 in synchronization with the output of the dimming stop signal to the sensitivity control circuit 132.

  Open / close position information of the diaphragm 51 is input from the diaphragm control circuit 152 to the dimming switching circuit 137. The dimming switching circuit 137 outputs a dimming stop signal to the diaphragm control circuit 152 when the diaphragm 51 reaches a predetermined position. The dimming switching circuit 137 outputs a dimming permission signal to the sensitivity control circuit 132 in synchronization with the output of the dimming stop signal to the aperture control circuit 152.

  The dimming switching circuit 137 does not output the dimming permission signal or the dimming stop signal to both the sensitivity control circuit 132 and the aperture control circuit 152, and outputs the dimming permission signal to one of the other. A dimming stop signal is output to

(Function)
The dimming at the time of fluorescence observation of the second embodiment will be described.
In the fluorescence observation, when observing a living tissue, the intensity of incident light on the CCD 19 varies with changes in the state of the living tissue or the distance between the living tissue and the distal end of the endoscope 2, and the brightness of the monitor 6 is increased. The screen average value may not match the target value selected by the operator with the brightness control switch 59.

  In this case, the photometry circuit 136 calculates the luminance signal of the constructed fluorescent image composed of the fluorescence wavelength and the two wavelengths of the reflected light, and outputs the luminance signal to the sensitivity control circuit 132 and the aperture control circuit 152.

  When a living tissue is observed with fluorescence at a distance from a far point to a near point, and the incident intensity to the CCD 19 is very small compared with that during normal light observation, the following light control operation is performed.

  In this case, the dimming switching circuit 137 outputs a dimming permission signal to the sensitivity control circuit 132 and outputs a dimming stop signal to the aperture control circuit 152.

  The sensitivity control circuit 132 compares the brightness target value selected by the operator with the brightness control switch 59 in the comparison circuit 81 with the luminance signal, and the counter values Cmin to Cma that are increased or decreased according to the comparison result. Is output from the up / down counter 183 to the CCD driving circuit 131 and the dimming switching circuit 137.

  The CCD drive circuit 131 outputs voltages Vth to Vmax corresponding to the up and down counter values Cmin to Cmax as the sensitivity control pulse φCMD applied to the charge amplifier 64 (see FIG. 2). The sensitivity amplification factor of the CCD 19 increases and decreases according to the increase and decrease of the voltage of the sensitivity control pulse φCMD, and the sensitivity control circuit 132 changes the luminance signal to compensate for the fluctuation of the incident light intensity to the CCD 19, and the luminance signal becomes brighter. Automatic gain control is performed so as to match the target value of.

  Since the dimming stop signal is input from the dimming switching circuit 137 to the aperture control circuit 152, the aperture control circuit 152 forcibly stops the opening / closing operation of the aperture 51, and the aperture 51 is fixed at a predetermined position. (Held). Thereby, the irradiation intensity to the rear end face of the light guide 12 becomes the maximum value.

  When fluorescence observation is performed on the living tissue at a distance from the near point and the incident intensity on the CCD 19 becomes the same level as that during normal light observation, the following light control operation is performed.

  In this case, the dimming switching circuit 137 outputs a dimming permission signal to the aperture control circuit 152 and outputs a dimming stop signal to the sensitivity control circuit 132.

  The diaphragm control circuit 152 compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59, and controls the opening / closing operation of the diaphragm 51 according to the comparison result.

  The aperture control circuit 152 operates to close the aperture 51 when the luminance signal is brighter than the target value, and operates to open the aperture 51 when the monitor screen is darker than the target value. Thereby, the aperture control circuit 152 performs control so that the brightness of the monitor screen is maintained at the operator's target value by changing the irradiation intensity of the irradiation light to the living tissue.

  On the other hand, since the dimming stop signal is input from the dimming switching circuit 137 to the sensitivity control circuit 132, the up / down counter 183 is forcibly stopped, and the CCD driving circuit 131 and the dimming switching circuit 137 have counters. The value Cmin is output, and the sensitivity amplification factor of the CCD 19 is fixed to 1 time.

  When a biological tissue is observed for fluorescence near the near point distance and the incident intensity to the CCD 19 is relatively small compared to that for normal light observation, the following light control operation is performed.

  In this case, the dimming switching circuit 137 alternately outputs a dimming permission signal (dimming stop signal) to the aperture control circuit 152 and the sensitivity control circuit 132 according to the situation.

  When the intensity of incident light on the CCD 19 varies in a state where the sensitivity amplification factor is 1 to 2 times, the voltage value of the sensitivity control pulse φCMD from the CCD drive circuit 131 gradually decreases, and accordingly. The sensitivity amplification factor of the CCD 19 is also reduced and the sensitivity amplification factor becomes one. Since the counter value output from the up / down counter 183 to the dimming switching circuit 137 is Cmin corresponding to a sensitivity amplification factor of 1, the dimming switching circuit 137 outputs a dimming stop signal to the sensitivity control circuit 132 to increase the counter value. The operation of the down counter 183 is stopped. As a result, the counter output to the CCD driving circuit 131 is fixed to Cmin, and the sensitivity amplification factor of the CCD 19 is fixed to 1. On the other hand, the dimming switching circuit 137 outputs a dimming permission signal to the diaphragm control circuit 152 to permit the opening / closing operation of the diaphragm 51. The diaphragm control circuit 152 selects the luminance signal and the operator with the brightness control switch 59. The brightness target value is compared, and the opening / closing operation of the diaphragm 51 is controlled according to the comparison result.

  If the intensity of incident light on the CCD 19 fluctuates in the direction in which the diaphragm 51 is operated, the diaphragm 51 operates in the opening direction and assumes a predetermined position. The aperture position information output from the aperture control circuit 152 to the dimming switching circuit 137 is a predetermined position, and the dimming switching circuit 137 outputs a dimming stop signal to the aperture control circuit 152 to set the open / close position of the aperture 51 to a predetermined level. Fix in position. On the other hand, the dimming switching circuit 137 outputs a dimming permission signal to the sensitivity control circuit 132 to permit the counter operation of the up / down counter 183. The sensitivity control circuit 132 determines whether the brightness signal and the operator operate the brightness control switch 59. The brightness target value selected in (1) is compared, and the voltage value of the sensitivity control pulse φCMD output from the CCD drive circuit 131 is increased or decreased by increasing or decreasing the counter value according to the comparison result, thereby increasing or decreasing the sensitivity gain of the CCD 19. Take control.

(effect)
According to the second embodiment, in the special light mode (fluorescence observation), the dimming operation is performed by appropriately separating the sensitivity amplification factor of the sensitivity variable CCD and the aperture of the light source. As a fluorescent image that is a composite image of light, even if the incident intensity to the CCD fluctuates greatly, saturation of the image can be prevented and a more appropriate brightness and high quality image can be obtained.

(Third embodiment)
FIGS. 16 to 21 relate to a third embodiment of the present invention, FIG. 16 is a block diagram showing a schematic configuration of an endoscope apparatus, FIG. 17 is a timing chart for driving a CCD, and FIG. 19 is a graph showing the spectral characteristics of the light source device in FIG. 19, FIG. 19 is a graph showing the spectral characteristics of reflected light in narrow-band light observation, FIG. 20 is a graph showing the CCD sensitivity characteristics (monitor output signal), and FIG. / N characteristic).

  In the description of the third embodiment of the present invention with reference to FIGS. 16 to 21, the same components as those in the first embodiment shown in FIGS. Omitted.

(Constitution)
As shown in FIG. 16, an endoscope apparatus 201 according to the third embodiment is compatible with narrow-band light observation as a special light mode, and includes an endoscope 202, a processor 203, and a monitor 6. Have.

  The endoscope 202 is detachably connected to the processor 203. The processor 203 includes a signal processing device 204 and a light source device 205. Note that the light source device 205 may be provided separately from the processor 203.

The endoscope 202 has an elongated insertion portion 211 to be inserted into a patient body cavity.
Inside the insertion portion 211, a light guide 12, a CCD drive signal line 13, and a CCD output signal line 14 are disposed.

  The distal end portion 215 of the insertion portion 211 is provided with the distal end side of the light guide 12, the illumination lens 16, the objective lens 17, and the CCD 19. However, in the third embodiment, the tip portion 215 is not provided with an excitation light cut filter.

  The light guide 12 guides illumination light from the light source device 205 provided in the processor 203 to the distal end portion 215 of the insertion portion 211.

Light from the subject is imaged on the light receiving surface of the CCD 19 via the objective lens 17.
The CCD 19 is connected to the CCD drive means 231 of the signal processing device 204 in the processor 203 via the drive signal line 13. The CCD 19 performs electronic shutter control and signal charge accumulation based on the drive signal generated by the CCD drive circuit 231.

  The subject image that is transmitted through the objective lens 17 and formed on the light receiving surface of the CCD 19 is transferred after photoelectric conversion in each pixel of the CCD 19 and output from the output amplifier.

  An output signal from the CCD 19 is output to the analog processing circuit 33 of the signal processing means 204 in the processor 203 via the CCD output signal line 14.

  The endoscope 202 is equipped with a storage device 220. The storage device 220 includes a CPU 221 and a nonvolatile memory 222.

  The CPU 221 controls data read / write control to the memory 222 and data transmission / reception (communication) with the processor 203.

  The memory 222 as a storage means stores the accumulation time of three wavelengths of R, G, and B (electronic shutter speed) in the normal light mode and the accumulation time of three wavelengths in the special light mode (narrowband light observation) ( Electronic shutter speed) is stored.

  In the present embodiment, the signal processing device 204 includes a CPU 30, a CCD drive circuit 231, a sensitivity control circuit 32, an analog processing circuit 33, an A / D converter 34, a digital processing circuit 35, and a photometric circuit 36. A photometric correction circuit 37, a selector 40, synchronization memories 41, 42, 43, a matrix circuit 44, D / A converters 45, 46, 47, and a 75Ω driver 48.

  The light source device 205 includes a lamp 50, a diaphragm 51, a diaphragm control circuit 52, a rotation filter 253, a motor 54, a condenser lens 55, a rotation filter switching mechanism 256, a rotation filter control circuit 257, A mode changeover switch 58, a brightness control switch 59, a filter changeover mechanism 281 and an optional filter 282 are provided.

  FIG. 17 is a timing chart of the drive signal and output signal of the CCD 19 for one wavelength of the three wavelengths, FIG. 17A shows the operation of the rotary filter 253, and FIG. 17B shows the vertical transfer pulses φP1, φP2, 17C shows the sensitivity control pulse φCMD in the special light mode, FIG. 17D shows the horizontal transfer pulses ΦS1 and ΦS2, and FIG. 17E shows the output signal from the CCD 19, respectively.

  In FIG. 17, the CCD 19 is capable of accumulating light incident from the subject on the light receiving surface of the CCD 19 as a signal charge by photoelectric conversion during the exposure period shown in FIG.

  In the light shielding period shown in FIG. 17A, the CCD driving unit 131 sends the CCD 19 the vertical transfer pulses φP1 and φP2 shown in FIG. 17B and the horizontal transfer pulses φS1 and φS2 (d) shown in FIG. The sensitivity control pulse φCMD (in the special light mode) shown in FIG.

  The CCD 19 transfers the signal charges accumulated during the exposure period to the horizontal transfer path for each horizontal line by the vertical transfer pulses φP1 and φP2 shown in FIG. 17B, and the horizontal transfer pulse φS1 shown in FIG. , .PHI.S2 are sequentially transferred to the output amplifier of the CCD 19, and converted into a charge voltage by the output amplifier and output as an output signal shown in FIG.

  Here, in this embodiment, the transmission part and the light shielding part of the rotary filter 253 are formed so that the exposure time (accumulation time) is the same in the normal light mode and the special light (narrow band light observation) mode. .

  Further, the drive signal excluding the sensitivity control pulse φCMD of the CCD 19 and the output timing of the CCD 19 are the same in the normal light mode and the special light (narrowband light observation) mode.

  The rotary filter 253 is inserted on the illumination optical path of the lamp 50 and the condenser lens 55, is connected to the rotary shaft of the motor 54, and is rotated at a predetermined speed by the rotary filter control circuit 257.

  The rotation filter control circuit 257 can arbitrarily control the rotation speed of the rotation filter 253 (motor 54). In the present embodiment, the rotation speed of the special mode (narrowband light observation) by the rotary filter control circuit 257 is the same as that of the normal light mode.

  The rotary filter switching mechanism 256 selectively selects the first filter set on the inner peripheral side and the second filter set on the outer peripheral side of the rotary filter 253 on the illumination optical axis connecting the lamp 50 and the rear end surface of the light guide 12. This is a mechanism for moving the entire rotary filter 253. The rotary filter switching mechanism 256 may or may not move the rotary filter 253 depending on the type of special light observation. The rotary filter switching mechanism 256 does not move the rotary filter 253 in narrowband light observation as in normal light.

  The optional filter 282 is a filter having a transmission characteristic in which at least one wavelength band is limited with respect to the R, G, and B broadband wavelengths by the rotary filter 253.

  In the present embodiment, the option filter 282 has the following three-peak transmission characteristics.

  The transmission characteristic of B 'of the option filter 282 has a center wavelength of 415 nm and a half width of 30 nm. The G ′ transmission characteristics of the optional filter 282 have a center wavelength of 540 nm and a half width of 30 nm. The transmission characteristic of R ′ of the optional filter 282 has a center wavelength of 620 nm and a half width of 30 nm.

  When the optional filter 282 is inserted on the illumination optical axis connecting the lamp 50 and the rear end surface of the light guide 12, the illumination light emitted from the lamp 50 passes through the optional filter 282 and the rotary filter 253, and is shown by the solid line in FIG. Illumination light having a narrow band spectral characteristic as shown in FIG. Further, the broken line in FIG. 18 indicates the broadband spectral characteristics of R, G, and B by the rotary filter 253.

  The filter switching mechanism 281 is a mechanism that moves the entire optional filter 282, and moves (inserts / removes) the optional filter 282 on the illumination optical axis that connects the lamp 50 and the rear end surface of the light guide 12.

  The filter switching mechanism 281 operates in response to a mode switching signal (narrow band light) from the mode switching switch 58.

  The filter switching mechanism 281 removes the option filter 282 from the illumination light path in the normal light mode, and arranges the option filter 282 on the illumination light path in the special light mode (narrow band light observation).

(Function)
A method of using the endoscope apparatus 201 according to the third embodiment will be described below.

  In starting the endoscopy, the operator connects the type of endoscope 202 corresponding to the observation site and the type of observation to the processor 203 from a plurality of types of endoscopes. The CPU 30 of the processor 203 reads various data related to the endoscope 202 stored in the memory 222 via the CPU 221 of the storage device 220 of the endoscope 202. The sensitivity amplification factor characteristic (relationship between voltage value and sensitivity amplification factor) data of the CCD 19 stored in the memory 222 is output to the CCD drive circuit 231 via the CPU 30.

Next, the operation in the narrow-band light observation used as the special light mode will be described.
When performing narrow-band light observation, the operator selects narrow-band light observation from a plurality of observation modes of the mode switch 58. In synchronization with this, the filter switching mechanism 281 operates, and the optional filter 282 is disposed on the illumination light path of the lamp 50 and the light guide 12. Further, the rotary filter switching mechanism 256 does not operate, and the rotary filter 253 has the same first filter set as that used during normal light observation arranged on the illumination optical path.

  Illumination light emitted from the lamp 50 of the light source device 205 passes through the first filter set of the optional filter 282 and the rotary filter 253, and has a narrow band in the wavelength range of R ′, G ′, and B ′ as shown in FIG. Light illumination light is incident on the rear end surface of the light guide 12 via the condenser lens 55, and is irradiated in time series on the living tissue from the illumination lens 16 provided at the distal end portion 211 of the endoscope 202. .

  Reflected light (returned light) of narrow band light irradiated on the living tissue through the objective lens 17 is incident on the light receiving surface of the CCD 19. In this case, light having spectral characteristics as shown in FIG. 19 is incident on the light receiving surface of the CCD 19.

  The blue (B2), green (G2), and red (R2) narrow-band reflected light from the biological tissue shown in FIG. 19 is sequentially incident on the CCD 19, and the output signal of the CCD 19 corresponding to each wavelength is input to the signal processing device 204. Then, predetermined signal processing is performed by the analog processing circuit 33 and the digital processing circuit 35, and output to the monitor 6 and peripheral devices via the selector 40, the synchronization memories 41, 42, 43, the matrix circuit 44, and the 75Ω driver 48. A narrow-band reflected light image is displayed and recorded.

  Further, in the digital processing circuit 35, the white balance coefficient at the time of imaging of the blue, green, and red narrow band reflected light is set for narrow band light observation from among a plurality stored in the memory 222. In the matrix circuit 44, predetermined color conversion is performed between the images of the respective wavelengths.

  In such narrow-band light observation, when observing a living tissue, the intensity of incident light on the CCD 19 varies with the variation of the state of the living tissue and the distance between the living tissue and the distal end of the endoscope 2. The luminance signal of the monitor 6 may not match the target value selected by the operator with the brightness control switch 59. In that case, the following light control is performed.

  The photometry circuit 36 calculates a luminance signal of a narrowband light image constructed from narrowband reflected light of three wavelengths and outputs the luminance signal to the sensitivity control circuit 32 and the photometry correction circuit 37. The sensitivity control circuit 32 compares the brightness target value selected by the operator with the brightness control switch 59 with the brightness signal in the comparison circuit (see the comparison circuit 81 in FIG. 7), and corresponds to the comparison result. The up / down counter (see the up / down counter 83 in FIG. 7) outputs the up / down counter value to the CCD drive circuit 231. The CCD drive circuit 231 sets the sensitivity control pulse φCMD output to the charge amplifier 64 (see FIG. 2) of the CCD 19 to a voltage value corresponding to the up / down counter value. As a result, the sensitivity amplification factor of the CCD 19 increases / decreases in accordance with the voltage value of the sensitivity control pulse φCMD, and the sensitivity of the CCD 19 is compensated to compensate for the change in the incident light intensity on the CCD 19 in the entire endoscope apparatus 201. The brightness of the monitor 6 is changed by increasing / decreasing the rate, and control is performed so that the luminance signal matches the target value of brightness.

  The CCD drive circuit 231 outputs the sensitivity amplification factor of the charge amplifier 64 (see FIG. 2) to the photometric correction circuit 37. The photometric correction circuit 37 calculates [(luminance signal) / (sensitivity amplification factor)] based on the luminance signal from the photometry circuit 36 and the sensitivity amplification factor from the CCD drive circuit 231 to increase the sensitivity amplification factor by one. The luminance signal in the state is output to the aperture control circuit 52.

  The diaphragm control circuit 52 compares the luminance signal with the brightness target value selected by the operator using the brightness control switch 59, and performs opening / closing control of the diaphragm 51 according to the comparison result.

  The diaphragm control circuit 52 operates to close the diaphragm 51 when the luminance signal is brighter than the target value, and operates to open the diaphragm 51 when the luminance signal is darker than the target value to irradiate the living tissue. By changing the light irradiation intensity, an automatic light control operation is performed by controlling the diaphragm 51 so that the brightness of the monitor 6 matches the target value.

  Here, since the reflected light of the narrow band light is weak with respect to the normal light, the sensitivity amplification factor is sufficient to obtain sufficient brightness of the monitor when observing the biological tissue in the narrow band light from the far point to the near point. Dozens of times. Therefore, the luminance signal corrected by the photometric correction circuit 37 becomes very small, so that the diaphragm 51 is controlled in the opening direction and held at the fully open position. In the sensitivity control circuit 32, the brightness target value of the monitor 6 is compared with the luminance signal, and the CCD drive circuit 231 is controlled to increase the voltage value (amplitude) of the sensitivity control pulse φCMD according to the comparison result. By doing so, the luminance signal is changed by increasing / decreasing the sensitivity amplification factor of the CCD 19, and control is performed so that the luminance signal matches the target brightness value. In this case, automatic dimming operation based only on the sensitivity amplification factor of the charge amplification unit 64 (see FIG. 2) of the CCD 19 (dimming control by preferentially controlling the sensitivity amplification factor of the charge amplification unit 64) is performed.

  When the biological tissue is enlarged and observed in a narrow band at a near point and the incident light intensity to the CCD 19 becomes large and becomes a normal light level, the sensitivity amplification of the CCD 19 becomes unnecessary. Then, the sensitivity amplification factor output from the CCD drive circuit 231 to the photometry correction circuit 37 is multiplied by 1. In the photometry correction circuit 37, the luminance signal and the sensitivity amplification factor are divided by using the sensitivity amplification factor of 1. The aperture control circuit 52 outputs the same value as the output value from the photometry circuit 36.

  The diaphragm control circuit 52 compares the luminance signal with the brightness target value selected by the operator using the brightness control switch 59, and performs opening / closing control of the diaphragm 51 according to the comparison result. When the luminance signal is brighter than the target value, control is performed so that the diaphragm 51 is closed. When the luminance signal is darker than the target value, control is performed so that the diaphragm 51 is opened. In this case, an automatic dimming operation using only the aperture 51 (a dimming operation by preferentially controlling the aperture opening / closing operation of the light source device) is performed.

  When the biological tissue is observed in a narrow band at a near point and the incident light intensity on the CCD 19 becomes relatively larger than that of the normal light, a situation in which the sensitivity amplification factor is 1 to 2 times occurs and the photometric correction circuit 37 corrects the situation. The luminance signal becomes large. In the aperture control circuit 52, the brightness target value selected by the operator with the brightness control switch 59 and the corrected luminance signal are at the same level.

  As a result, when the intensity of incident light on the CCD 19 fluctuates in the direction of increasing, the sensitivity gain of the CCD 19 gradually decreases, and the diaphragm 51 also operates in the direction of gradually closing in conjunction with it.

  Further, when the incident light intensity to the CCD 19 fluctuates in the direction of decreasing, the diaphragm 51 is operated to gradually open, and the sensitivity amplification factor is gradually increased in conjunction with it. In this case, an automatic dimming operation in which the sensitivity amplification factor of the charge amplifying unit 64 (see FIG. 2) and the opening / closing of the aperture 51 operate simultaneously in conjunction with each other (linked control of the sensitivity amplification factor of the CCD and the aperture opening / closing operation of the light source device). Dimming operation).

  The monitor 6 can obtain the output signal and its S / N characteristic shown by the solid lines in FIGS. In the narrow-band light region (CCD incident light intensity in FIGS. 20 and 21 is in the vicinity of 0.01 to 0.1 [au]), the sensitivity gain of the CCD 19 is increased with respect to the normal light mode. Output signals and S / N characteristics such as double, triple, and triple are obtained. In the narrow-band light region, when the sensitivity amplification factor is 1, the monitor screen is dark and the S / N characteristics are very poor. However, by increasing the sensitivity amplification factor several times or several tens of times, the monitor screen is bright and a narrow-band light image with high S / N characteristics (high image quality) can be obtained. The sensitivity amplification factor can be amplified to an arbitrary value by controlling the applied voltage value (amplitude).

  Narrow-band light observation is performed by illuminating a living tissue with narrow-band light with a limited wavelength range, particularly in the blue region (short wavelength side). It is characterized by being able to capture blood vessel images more sensitively than normal light observation.

  This is because the depth of light in the depth direction of the mucosa is wavelength-dependent, and the shorter the wavelength, the smaller the depth of penetration due to the influence of scattering (shallow), and the mucosa (living body) is near 415 nm. This is because, since there is a large absorption band of hemoglobin, the fine structure of the mucosal surface layer and capillaries can be specifically detected when irradiated with narrow-band light in the vicinity of 400 to 450 nm. Therefore, the structure of the mucosal surface layer and the running pattern of capillaries that are very difficult to observe in normal light observation can be drawn very clearly by using narrow-band light observation. It is possible to facilitate qualitative diagnosis of tumor / non-tumor, benign tumor / malignant tumor, etc. by observing the fine structure of the mucosa and the running pattern of capillaries in detail, for example, by magnifying observation. .

(effect)
According to the third embodiment, in the special light mode (narrowband light observation), the dimming control is appropriately linked with the sensitivity amplification factor of the sensitivity variable CCD 19 and the diaphragm 51 of the light source device 205. As a narrow-band light image, even when the incident intensity on the CCD 19 fluctuates greatly, image saturation can be prevented and a more appropriate brightness and high-quality image can be obtained.

(Fourth embodiment)
22 and 23 relate to the fourth embodiment of the present invention, FIG. 22 is a block diagram showing a schematic configuration of the endoscope apparatus, and FIG. 23 is a block diagram showing a configuration of the sensitivity control circuit of FIG. .

  In the description of the fourth embodiment using FIG. 22 and FIG. 23, the same components as those of the third embodiment shown in FIG. 16 to FIG.

(Constitution)
In the third embodiment shown in FIGS. 16 to 21, the sensitivity gain of the variable sensitivity CCD and the aperture of the light source are interlocked during the dimming operation in the special light mode. The fourth embodiment In the endoscope apparatus 301, a dimming switching circuit 337 is provided, and the dimming operation is performed by either changing the sensitivity gain of the CCD 19 or opening / closing the diaphragm 51.

  As illustrated in FIG. 22, an endoscope apparatus 301 according to the fourth embodiment includes an endoscope 202, a processor 303, and a monitor 6.

  The endoscope 202 is detachably connected to the processor 303. The processor 303 includes a signal processing device 304 and a light source device 305. Note that the light source device 305 may be provided separately from the processor 303.

  The monitor 6 is connected to the processor 303 and displays a video signal image-processed by the processor 303.

  In this embodiment, the signal processing device 304 includes a CPU 30, a CCD drive circuit 331, a sensitivity control circuit 332, an analog processing circuit 33, an A / D converter 34, a digital processing circuit 35, and a photometric circuit 336. , A dimming switching circuit 337, a selector 40, synchronization memories 41, 42, 43, a matrix circuit 44, D / A converters 45, 46, 47, and a 75Ω driver 48.

  The light source device 305 includes a lamp 50, a diaphragm 51, a diaphragm control circuit 352, a rotation filter 253, a motor 54, a condenser lens 55, a rotation filter switching mechanism 256, a rotation filter control circuit 257, and a mode switching. A switch 58, a brightness control switch 59, a filter switching mechanism 281 and an optional filter 282 are provided.

  The operation (exposure, light shielding) of the rotary filter 253 in the normal light mode and special light (narrowband light observation) mode, the timing of the drive signal supplied to the CCD 19 by the CCD drive circuit 331, and the timing of the output signal from the CCD 19 are as follows: This is the same as the third embodiment shown in FIGS.

  Counter values Cmin to Cmax are input from the sensitivity control circuit 332 to the CCD drive circuit 331.

  The counter values Cmin to Cmax are related to the voltage value of the sensitivity control pulse φCMD output from the sensitivity control circuit 332 to the charge amplifier 64 (see FIG. 2) of the CCD 19.

  The CCD drive circuit 331 receives data of sensitivity amplification factor characteristics (relationship between applied voltage and sensitivity amplification factor) of the charge amplification unit 64 (see FIG. 2) of the CCD 19 from the memory 222 via the CPU 221 and the CPU 30. The

  The correspondence between the counter values Cmin to Cmax and the applied voltage values Vth to Vmax (see FIG. 4) to the charge amplifying unit 64 (see FIG. 4) is the same as in the second embodiment when the counter value is the minimum Cmin. The voltage Vth is set to be the voltage Vmax when the counter value is the maximum Cmax.

  Then, the CCD drive circuit 331 outputs the sensitivity control pulse φCMD corresponding to the counter values Cmin to Cmax to the charge amplifier 64 (see FIG. 2) of the CCD 19 in the range of Vth to Vmax.

  The CCD drive circuit 331 has correction means for matching the minimum value Vth and the maximum value Vmax of the sensitivity control pulse φCMD voltage with the minimum Cmin and the maximum Cmax of the counter value.

  In the fourth embodiment, the relationship between the voltage value of the sensitivity control pulse ΦCMD of the charge amplifier 64 (see FIG. 2) and the sensitivity amplification factor is the same as in the third embodiment.

  The photometric circuit 336 of the fourth embodiment is different from the third embodiment in that the luminance signal calculated for each observation mode is added to the sensitivity control circuit 332 and also output to the aperture control circuit 352. is there.

  As shown in FIG. 23, the sensitivity control circuit 332 includes a comparison circuit 381, an LUT circuit 382, an up / down counter 383, and a decoding circuit 384.

  The up / down counter 383 increases or decreases the counter values Cmin to Cmax (C ′ = C ± 1) based on the comparison result between the luminance signal input from the comparison circuit 381 and the brightness target value.

  The up / down counter 383 outputs the counter value to the CCD driving circuit 331, the dimming / switching circuit 337, and the decoding circuit 384. The up / down counter 383 stops the counter output at the maximum value Cmax when the stop signal is input from the decode circuit 384. Further, the up / down counter 383 sets the counter output to the minimum value Cmin and stops the counter operation when the mode switching signal from the mode switch 58 is in the normal light mode. That is, the sensitivity control circuit 332 operates only in the special light mode.

  The decode circuit 384 determines whether or not an overflow (described in the second embodiment) is detected from the counter values Cmin to Cmax input from the up / down counter 383, and outputs a stop signal to the up / down counter 383 in the case of an overflow. .

  The dimming switching circuit 337 switches and selects one of the dimming permission signal and the dimming stop signal and inputs it to the up / down counter 383. The up / down counter 383 starts the count operation when the dimming permission signal is input, and stops the count operation with the counter value Cmin when the dimming stop signal is input.

  The light source device 305 of the fourth embodiment is different from the light source device 205 of the third embodiment only in an aperture control circuit 352.

  The aperture control circuit 352 receives the luminance signal from the photometry circuit 336, and compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59. From the comparison result, the diaphragm control circuit 352 controls the opening / closing operation of the diaphragm 51 inserted on the optical path of the lamp 50 and the rotary filter 253, and controls the amount of illumination light to the rear end face of the light guide 12.

  The aperture control circuit 352 receives a dimming permission signal or dimming stop signal from the dimming switching circuit 337. The aperture control circuit 352 starts the opening / closing operation control of the aperture 51 by inputting the dimming permission signal, and fixes (holds) the aperture 51 at a predetermined position (described in the second embodiment) by inputting the dimming stop signal. )

  There are two dimming methods for the processor 303, namely, variable sensitivity gain of the CCD 19 and opening / closing operation of the aperture 51 of the light source device 305. The dimming switching circuit 337 determines and switches one of the two dimming methods. Circuit.

  Counter values Cmin to Cmax indicating sensitivity gain are input to the dimming switching circuit 337 from the sensitivity control circuit 332. The dimming switching circuit 337 outputs a dimming stop signal to the sensitivity control circuit 332 when a counter value Cmin corresponding to a sensitivity amplification factor of 1 is input. The dimming switching circuit 337 outputs a dimming permission signal to the aperture control circuit 352 in synchronization with the output of the dimming stop signal to the sensitivity control circuit 332.

  The dimming / switching circuit 337 receives the opening / closing position information of the diaphragm 51 from the diaphragm control circuit 352. The dimming switching circuit 337 outputs a dimming stop signal to the diaphragm control circuit 352 when the diaphragm 51 reaches a predetermined position. The dimming switching circuit 337 outputs a dimming permission signal to the sensitivity control circuit 332 in synchronization with the output of the dimming stop signal to the aperture control circuit 352.

  The dimming switching circuit 337 does not output the dimming permission signal or the dimming stop signal to both the sensitivity control circuit 332 and the aperture control circuit 352, and outputs the dimming permission signal to one of the other. A dimming stop signal is output to

(Function)
A method of using the endoscope apparatus 301 according to the fourth embodiment will be described below.

In the following, light control during narrowband light observation will be described.
When performing narrow-band light observation, the operator selects narrow-band light observation from a plurality of observation modes of the mode switch 58. In synchronization with this, the filter switching mechanism 281 operates, and the optional filter 282 is disposed on the illumination light path of the lamp 50 and the light guide 12. Further, the rotary filter switching mechanism 256 does not operate, and the rotary filter 253 has the same first filter set as that used during normal light observation arranged on the illumination optical path.

  When observing a living tissue in narrowband light observation, the intensity of incident light on the CCD 19 varies with the state of the living tissue and the variation in the distance between the living tissue and the distal end of the endoscope 202, and the screen average value of the monitor 6 is In some cases, the surgeon may not match the target value selected by the brightness control switch 59.

  The photometry circuit 336 calculates a luminance signal of a narrowband light image constructed from narrowband light of three wavelengths, and outputs the luminance signal to the sensitivity control circuit 332 and the aperture control circuit 352.

  When narrow-band light observation is performed on a living tissue from a far point to a near point distance and the incident intensity on the CCD 19 is much smaller than that during normal light observation, the following light control operation is performed.

  The dimming switching circuit 337 outputs a dimming permission signal to the sensitivity control circuit 332 and outputs a dimming stop signal to the aperture control circuit 352. The sensitivity control circuit 332 compares the brightness target value selected by the operator with the brightness control switch 59 in the comparison circuit 381 with the luminance signal, and counts up and down counter values Cmin to Cmax according to the comparison result. The data is output from the up / down counter 383 to the CCD drive circuit 331 and the dimming / switching circuit 337.

  The CCD drive circuit 331 outputs a sensitivity control pulse φCMD applied to the charge amplifier 64 (see FIG. 2) at voltages Vth to Vmax corresponding to the up and down counter values Cmin to Cmax.

  The CCD 19 increases or decreases the sensitivity amplification factor according to the increase or decrease of the CMD voltage of the sensitivity control pulse φ, and the sensitivity control circuit 332 changes the luminance signal so as to compensate for the fluctuation of the incident light intensity to the CCD 19, and the luminance signal is Automatic gain control is performed to match the brightness target value.

  Since the dimming stop signal is input from the dimming switching circuit 337 to the aperture control circuit 352, the aperture control circuit 352 forcibly stops the opening / closing operation of the aperture 51, and the aperture 51 is fixed at a predetermined position. Is done. Thereby, the irradiation intensity to the rear end face of the light guide 12 becomes the maximum value.

  When narrow-band light observation is performed with respect to a living tissue at a near point distance and the incident intensity to the CCD 19 is at a level equivalent to that during normal light observation, the following light control operation is performed.

  In this case, the dimming switching circuit 337 outputs a dimming permission signal to the aperture control circuit 352 and outputs a dimming stop signal to the sensitivity control circuit 332.

  The diaphragm control circuit 352 compares the luminance signal with the target brightness value selected by the operator using the brightness control switch 59, and controls the opening / closing operation of the diaphragm 51 according to the comparison result.

  The aperture control circuit 352 operates to close the aperture 51 when the luminance signal is brighter than the target value, and operates to open the aperture 51 when the monitor screen is darker than the target value. Thereby, the aperture control circuit 352 performs control so that the brightness of the screen of the monitor 6 is maintained at the target value of the operator by changing the irradiation intensity of the irradiation light to the living tissue.

  On the other hand, since the dimming stop signal is input from the dimming switching circuit 337 to the sensitivity control circuit 332, the up / down counter 383 is forcibly stopped, and the CCD driving circuit 331 and the dimming switching circuit 337 have counters. The value Cmin is output, and the sensitivity amplification factor of the CCD 19 is fixed at 1 time.

  When narrow-band light observation is performed on the living tissue near the near point distance and the incident intensity to the CCD 19 is relatively small as compared with normal light observation, the following light control operation is performed.

  The dimming switching circuit 337 alternately outputs a dimming permission signal (dimming stop signal) to the aperture control circuit 352 and the sensitivity control circuit 332 according to the situation.

  When the incident light intensity to the CCD 19 varies in a state where the sensitivity amplification factor is 1 to 2 times, the voltage value of the sensitivity control pulse φCMD from the CCD drive circuit 331 gradually decreases, and accordingly, The sensitivity amplification factor of the CCD 19 is also reduced and the sensitivity amplification factor is increased by a factor of one. Since the counter value output from the up / down counter 383 to the dimming switching circuit 337 is Cmin corresponding to a sensitivity amplification factor of 1, the dimming switching circuit 337 outputs a dimming stop signal to the sensitivity control circuit 332 to increase the counter value. The operation of the down counter 383 is stopped. As a result, the counter output to the CCD drive circuit 331 is fixed to Cmin, and the sensitivity amplification factor of the CCD 19 is fixed to 1. On the other hand, the dimming switching circuit 337 outputs a dimming permission signal to the diaphragm control circuit 352 to permit the opening / closing operation of the diaphragm 51. The diaphragm control circuit 352 selects the luminance signal and the operator with the brightness control switch 59. The brightness target value is compared, and the opening / closing operation of the diaphragm 51 is controlled according to the comparison result.

  If the intensity of incident light on the CCD 19 fluctuates in the direction in which the diaphragm 51 is operated, the diaphragm 51 operates in the opening direction and assumes a predetermined position. The aperture position information output from the aperture control circuit 352 to the dimming switching circuit 337 is a predetermined position, and the dimming switching circuit 337 outputs a dimming stop signal to the aperture control circuit 352 to set the opening / closing position of the aperture 51 to a predetermined level. Fix in position. On the other hand, the dimming switching circuit 337 outputs a dimming permission signal to the sensitivity control circuit 332 to permit the counter operation of the up / down counter 383, and the sensitivity control circuit 332 determines whether the brightness signal and the operator operate the brightness control switch 59. The brightness target value selected in (1) is compared, and the voltage value of the sensitivity control pulse φCMD output from the CCD drive circuit 331 is increased or decreased by increasing or decreasing the counter value according to the comparison result, thereby increasing or decreasing the sensitivity gain of the CCD 19. Take control.

(effect)
According to the fourth embodiment, in the special light mode (narrow band light observation), the dimming control is performed by appropriately separating the sensitivity amplification factor of the sensitivity variable CCD 19 and the aperture of the light source. As a band light image, even if the incident intensity to the CCD 19 fluctuates greatly, saturation of the image can be prevented and a more appropriate brightness and high quality image can be obtained.

(Modification)
In the first and fourth embodiments, the charge amplifying unit may be mounted for each pixel. In this case, charge amplification can be performed by applying a sensitivity control pulse from the processor to the charge amplification section of the CCD, and the sensitivity amplification factor can be controlled by controlling the voltage value or the number of pulses of the sensitivity control pulse.

  In the first and fourth embodiments, the value at which the counter value is minimum corresponds to the voltage value (amplitude) of the sensitivity control pulse at which the sensitivity amplification factor is 1 (no amplification). The minimum value may be made to correspond to a voltage value (amplitude) at a predetermined sensitivity amplification factor other than 1 times the sensitivity amplification factor.

  In the first to fourth embodiments, the example in which the voltage value applied to the charge amplification unit is linearly ± ΔV (V) with respect to ± 1 change of the counter value is shown. The change in applied voltage may be made non-linear. For example, the change amount of the applied voltage is increased in a region where the counter value is small (region where the sensitivity gain is small), while the change amount of the applied voltage is decreased in a region where the counter value is large (region where the sensitivity gain is large). Various applications are possible.

  In the first to fourth embodiments, an example in which a CCD, which is one solid-state imaging device, is mounted on the distal end of the endoscope is shown. However, two CCDs are mounted on the distal end of the endoscope, and the first The CCD may be used for the normal light mode, and the second CCD may be used for the special light mode. In that case, CCD switching means for a CCD drive signal or readout signal such as a relay is provided in the endoscope or in the cable connecting the endoscope and the processor, and according to the mode switching signal from the mode switching circuit. The CCD corresponding to each observation mode may be driven and read out. In this case, for example, a plurality of signals common to the two CCDs are switched using a plurality of mechanical or electrical relays, and signals not common to the two CCDs can be connected between the CCD and the processor. By doing so, the number of cables connecting the processor and the endoscope can be reduced. Further, a CCD driving and reading circuit corresponding to two CCDs may be provided in the processor. The effect of the 2CCD type is that, when performing normal light observation, it is not necessary to provide an excitation light cut filter on the front surface of the CCD, so that better color reproducibility can be obtained.

  In the first to fourth embodiments, the CCD is mounted at the distal end portion of the endoscope. However, the outside of the fiberscope in which an image fiber for transmitting an image is provided in the endoscope (location other than the insertion portion). Alternatively, a CCD may be mounted on the device, and an integrated hybrid configuration or a detachable configuration may be used. As an effect, since the CCD does not have to be provided at the distal end of the endoscope, the outer diameter of the insertion portion can be reduced.

  In the first to fourth embodiments, a CCD with a variable sensitivity is used for imaging weak incident light as compared with normal light observation. However, in order to capture an image with higher S / N characteristics, accumulation is performed. It may be possible to combine time extension, pixel binning readout for adding peripheral pixels in the CCD, or performing arithmetic processing such as addition of multiple field images in the processor.

  In the first to fourth embodiments, the sensitivity gain characteristic data is stored in the storage device mounted on the endoscope. However, the sensitivity gain characteristic data may be stored in the processor.

  In the first and second embodiments, the three wavelengths of fluorescence observation are fluorescence, green reflected light, and red reflected light. However, the number of wavelengths of excitation light and reflected light, wavelength bands, transmittance, etc. can be selected. Various combinations can be applied, and only fluorescence may be acquired.

  In the first and second embodiments, examples of autofluorescence and reflected light are shown as special wavelengths for fluorescence observation, but not only autofluorescence but also a combination of drug fluorescence and reflected light may be used. In that case, various selections and combinations of the number of wavelengths of excitation light and reflected light, wavelength bands, and the like are applicable, and only drug fluorescence may be acquired.

  In the third and fourth embodiments, the three wavelengths of the narrowband light are each blue, green, and red narrowband light. Various selections and combinations of wavelengths and the like are applicable.

  In the third and fourth embodiments, the filter that generates narrowband light is provided in the option filter, but may be provided in the second filter set of the rotary filter. In this case, the combination with the R, G, and B filters for normal light is not necessary, and the degree of freedom in selecting and combining the number of wavelengths to be narrowed, the center wavelength, and the like is increased. For example, it is conceivable that three wavelengths are provided in the blue region and at least one wavelength is narrowband light, or at least one wavelength is narrowband in the ultraviolet light to visible light band.

  In the first to fourth embodiments, examples of the fluorescence observation and the narrow band light observation are shown as examples of the special light mode. For example, an ICG (Indocyanine Green) having a strong absorption band near 800 nm is used. Intravenously injected into the living tissue, the living tissue is irradiated with a plurality of wavelengths in the wavelength band near 800 nm (mainly observing the degree of ICG absorption) and the wavelength band near 900 nm (role of reference light), and the reflected light is irradiated Infrared observation is also possible by changing the wavelength characteristics of the filter. Various selections and combinations of the number of wavelengths to be illuminated during infrared observation, wavelength bands, and the like can be applied.

  In the first to fourth embodiments, the sensitivity amplification control of the solid-state image sensor is stopped during normal light observation. However, the sensitivity amplification of the solid-state image sensor is also performed during normal light observation as in the special light observation. It is also possible to perform control.

  In the first to fourth embodiments, the dimming operation is appropriately combined with the sensitivity amplification factor control of the CCD and the aperture control of the light source, but an electronic shutter may be further combined.

  Further, in the first to fourth embodiments, a mechanism for switching the gain value of the preamplifier of the analog processing circuit 33 according to the observation mode may be used. In this configuration, the gain value of the preamplifier in the special light mode is set larger than that in the normal light mode. By switching the gain of the preamplifier in synchronization with the operation of the mode switch 58, the CCD output signal of special light is greatly amplified by the preamplifier with respect to the normal light.

[Appendix]
According to the above-described embodiment of the present invention described in detail above, the following configuration can be obtained.

(Additional Item 1) An endoscope having a solid-state imaging device capable of changing sensitivity by amplifying a charge generated by supplying a pulsed signal;
A light source device that emits illumination light to the subject so that the solid-state imaging element forms a subject image;
A driving circuit for driving the solid-state imaging device and supplying a pulsed signal to the solid-state imaging device in order for the solid-state imaging device to perform charge amplification;
A signal processing circuit for processing an output signal from the solid-state imaging device;
A photometric circuit that performs photometry of an output signal from the solid-state imaging device;
A sensitivity control circuit that performs automatic gain control by controlling the sensitivity gain of the solid-state imaging device based on a photometric signal from the photometric circuit;
A photometric correction circuit for performing a calculation for correcting the photometric signal with a sensitivity amplification factor of the solid-state imaging device;
An aperture control circuit that performs light control by controlling the aperture of the light source device based on the photometric signal corrected by the photometric correction circuit;
An endoscope apparatus comprising:

(Additional Item 2) An endoscope having a solid-state imaging device whose sensitivity can be varied by amplifying a charge generated by supplying a pulsed signal;
A light source device that emits illumination light to the subject so that the solid-state imaging element forms a subject image;
A driving circuit for driving the solid-state imaging device and supplying a pulse-like signal for charge amplification to the solid-state imaging device;
A signal processing circuit for processing an output signal from the solid-state imaging device;
A photometric circuit that performs photometry of an output signal from the solid-state imaging device;
Based on the photometric result of this photometric circuit, a sensitivity control circuit that controls the gain of the solid-state image sensor and performs automatic gain control; and
An aperture control circuit that performs light control by controlling the aperture of the light source device based on the photometric result; and
A dimming switching circuit for operating either automatic gain control by sensitivity gain control of the solid-state image sensor or diaphragm control of the light source device;
An endoscope apparatus comprising:

  (Additional Item 3) The solid-state imaging device makes the sensitivity variable by amplifying the charge generated by the impact ionization caused by the supplied pulse-like signal and controlling the amplitude or the number of pulses of the pulse-like signal. The endoscope apparatus according to Additional Item 1 or 2, further comprising a charge amplifying unit.

  (Additional Item 4) The endoscope apparatus according to Additional Item 3, wherein the charge amplifying unit is provided between the horizontal transfer path and the output amplifier or for each pixel.

  (Additional Item 5) The additional light source device according to any one of Additional Items 1 to 4, wherein the light source device can be switched between normal light for performing normal light observation and a plurality of special lights for performing special light observation. Endoscope device.

  (Additional Item 6) The internal vision according to any one of Additional Items 1 to 5, further comprising mode switching means for switching an observation mode between a normal light mode for performing normal light observation and a special light mode for performing special light observation. Mirror device.

  (Additional Item 7) The endoscope apparatus according to Additional Item 6, wherein the special light mode is fluorescence observation.

  (Additional Item 8) The endoscope apparatus according to any one of Additional Items 5 to 7, wherein the plurality of special lights are excitation light for fluorescence and illumination light for reflected light.

  (Additional Item 9) The plurality of special lights are blue excitation light for fluorescence and green and red illumination light for reflected light. Endoscopic device.

  (Additional Item 10) The endoscope apparatus according to Additional Item 6, wherein the special light mode is narrow-band observation.

  (Additional Item 11) The endoscope apparatus according to any one of Additional Items 5 to 7, wherein the plurality of special lights are narrow-band illumination lights in which a wavelength band of at least one wavelength is limited.

  (Additional Item 12) The plurality of special lights are narrowband light in which a wavelength band of at least one wavelength is limited to blue, green, and red regions. Endoscope device.

  (Additional Item 13) The endoscope apparatus according to Additional Item 6, wherein the special light mode is infrared observation.

  (Additional Item 14) The endoscope apparatus according to any one of Additional Items 5 to 7, wherein the plurality of special lights are near-infrared illumination lights.

  (Additional Item 15) The endoscope apparatus according to Additional Item 6, wherein the special light mode is drug fluorescence observation.

  (Additional Item 16) The endoscope apparatus according to any one of Additional Items 5 to 7, wherein the plurality of special lights are excitation light for fluorescence and illumination light for reflected light.

  (Supplementary Item 17) The supplementary items 1, 3 to 16, wherein the photometric correction circuit performs a division operation on a photometric signal from the photometric circuit by a sensitivity amplification factor of the solid-state imaging device from the sensitivity control circuit. The endoscope apparatus according to any one of the above.

  (Additional Item 18) When the sensitivity gain of the solid-state imaging device reaches a predetermined value, the photometry switching circuit fixes sensitivity amplification control and outputs an aperture control permission signal to the aperture control circuit, or the aperture position is predetermined. The endoscope apparatus according to any one of appendices 2 to 17, wherein the position of the aperture is fixed at a predetermined opening / closing position and a permission signal for sensitivity gain control of the solid-state imaging device is output. .

  (Additional Item 19) The endoscope apparatus according to Additional Item 18, wherein the predetermined value of the sensitivity amplification factor is 1 time.

(Additional Item 20) An endoscope having an imaging device that is supplied with a pulse-like signal and whose sensitivity can be varied by amplifying the generated charge;
A light source for illuminating the subject,
An aperture for adjusting the amount of light applied to the subject;
Drive means for variably supplying the pulsed signal to the image sensor in order to vary the sensitivity of the image sensor;
Photometric means for measuring the output signal from the image sensor;
Sensitivity control means for controlling the sensitivity of the image sensor by controlling the charge amplification factor of the image sensor based on the photometric result of the photometry means;
A photometric correction means for correcting a photometric result by the photometric means based on the charge amplification factor;
Aperture control means for controlling the aperture based on the photometric signal corrected by the photometric correction means;
Signal processing means for processing an output signal from the image sensor;
An endoscope apparatus characterized by comprising:

(Additional Item 21) An endoscope having an imaging element to which a pulse-shaped signal is supplied and the sensitivity can be varied by amplifying the generated charge,
A light source for illuminating the subject,
An aperture for adjusting the amount of light applied to the subject;
Drive means for variably supplying the pulsed signal to the image sensor in order to vary the sensitivity of the image sensor;
Photometric means for measuring the output signal from the image sensor;
Sensitivity control means for controlling the sensitivity of the solid-state image sensor by controlling the charge amplification factor of the image sensor based on the photometric result;
A diaphragm control means for controlling the diaphragm based on the photometric result;
Dimming switching means for selectively operating either sensitivity control of the image sensor by the sensitivity control means or control of the diaphragm by the diaphragm control device according to a predetermined condition;
Signal processing means for processing an output signal from the solid-state imaging device;
An endoscope apparatus characterized by comprising:

1 is a block diagram showing a schematic configuration of an endoscope apparatus according to a first embodiment of the present invention. 1 is a block diagram of a charge coupled device solid-state imaging device according to a first embodiment of the present invention. 4 is a timing chart of sensitivity control pulse φCMD and horizontal transfer pulses φS1, φS2 according to the first embodiment of the present invention. 6 is a graph showing the relationship between the voltage applied to the charge amplification unit and the sensitivity amplification factor with respect to the CCD sensitivity according to the first embodiment of the present invention. 4 is a timing chart of CCD drive in the normal light mode according to the first embodiment of the present invention. 1 is a block diagram showing a configuration of a photometric circuit according to a first embodiment of the present invention. 1 is a block diagram showing a configuration of a sensitivity control circuit according to a first embodiment of the present invention. The block diagram which shows the structure of the photometry correction circuit of FIG. 1 which concerns on the 1st Embodiment of this invention. The top view which shows the structure of the rotary filter which concerns on the 1st Embodiment of this invention. 3 is a graph showing CCD sensitivity characteristics (monitor output signal) according to the first embodiment of the present invention. 3 is a graph showing CCD sensitivity characteristics (S / N characteristics) according to the first embodiment of the present invention. The graph which shows the spectral characteristic of the light source device which concerns on the 1st Embodiment of this invention in special light observation (fluorescence observation). The graph which shows the spectral characteristic of the fluorescence and reflected light in the special light observation (fluorescence observation) which concerns on the 1st Embodiment of this invention. The block diagram which shows schematic structure of the endoscope apparatus which concerns on the 2nd Embodiment of this invention. The block diagram which shows the structure of the sensitivity control circuit of FIG. 14 which concerns on the 2nd Embodiment of this invention. The block diagram which shows schematic structure of the endoscope apparatus which concerns on the 3rd Embodiment of this invention. 7 is a timing chart for driving a CCD according to a third embodiment of the present invention. The graph which shows the spectral characteristic of the light source device in the narrow-band light observation which concerns on the 3rd Embodiment of this invention. The graph which shows the spectral characteristic of the reflected light in the narrow-band light observation which concerns on the 3rd Embodiment of this invention. The graph which shows the CCD sensitivity characteristic (monitor output signal) which concerns on the 3rd Embodiment of this invention. The graph which shows the CCD sensitivity characteristic (S / N characteristic) which concerns on the 3rd Embodiment of this invention. The block diagram which shows schematic structure of this endoscope apparatus which concerns on the 4th Embodiment of this invention. The block diagram which shows the structure of the sensitivity control circuit which concerns on the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Endoscope apparatus 2 ... Electronic endoscope 3 ... Processor 4 ... Signal processing apparatus 5 ... Light source apparatus 6 ... Monitor 11 ... Insertion part 12 ... Light guide 16 ... Illumination lens 17 ... Objective lens 18 ... Excitation light cut filter 19 ... CCD
20 ... Storage device 21 ... CPU
22 ... Memory 30 ... CPU
DESCRIPTION OF SYMBOLS 31 ... CCD drive circuit 32 ... Sensitivity control circuit 33 ... Analog processing circuit 34 ... Analog / digital converter 35 ... Digital processing circuit 36 ... Photometry circuit 37 ... Photometry correction circuit 40 ... Selector 41, 42, 43 ... Synchronous memory 44 ... Matrix circuit 45, 46, 47 ... Digital / analog converter 48 ... 75Ω driver 50 ... Lamp 51 ... Aperture 52 ... Aperture control circuit 53 ... Rotation filter 54 ... Motor 55 ... Condensing lens 56 ... Rotation filter switching mechanism 57 ... Rotation filter Control circuit 58 ... Mode changeover switch 59 ... Brightness control switch

Claims (2)

An endoscope having an imaging element to which a pulse-shaped signal is supplied and the sensitivity can be varied by amplifying the generated charge;
A light source for illuminating the subject,
An aperture for adjusting the amount of light applied to the subject;
A photometric circuit for measuring the output signal from the image sensor;
A sensitivity control circuit for controlling the sensitivity of the image sensor by controlling a charge amplification factor of the image sensor based on a photometric result of the photometry circuit;
Based on the control of the sensitivity control circuit, the pulsed signal for changing the sensitivity of the imaging element is supplied to the imaging element, and the imaging element is controlled based on the voltage value of the pulsed signal. A drive circuit for calculating a sensitivity amplification factor;
A photometric correction circuit that generates a corrected luminance signal value by correcting the luminance signal from the photometric circuit to decrease and increase relatively according to an increase or decrease in the sensitivity amplification factor;
An aperture control circuit for controlling the aperture according to the corrected luminance signal value generated by the photometric correction circuit;
An endoscope apparatus characterized by comprising: According to the incident intensity to the image sensor,
If the incident intensity to the image sensor is relatively small, the sensitivity gain increases and the corrected luminance signal value decreases, control is performed to open the diaphragm according to the corrected luminance signal value, A first dimming control mode for performing dimming control by controlling the sensitivity control circuit while maintaining the full open state after the diaphragm has been fully opened;
A second dimming control mode in which dimming control is performed by controlling the aperture control circuit when the incident intensity to the image sensor is relatively large and the sensitivity gain is decreased to 1 time. When,
When the incident intensity to the image sensor is relatively larger than that in the first dimming control mode, and when the incident intensity to the image sensor is relatively smaller than in the second dimming control mode A third dimming control mode for performing dimming control by controlling both the sensitivity control circuit and the aperture control circuit;
An endoscope apparatus characterized by comprising:

Images