JP4033565B2 - Endoscope device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an endoscope apparatus that can more effectively expand the dynamic range of an imaging signal.
[0002]
[Prior art]
A medical endoscope is used for observation inside the body cavity. However, since the inside of the body cavity is dark, an illumination device that supplies illumination light into the dark body cavity is necessary. On the other hand, in an endoscope apparatus using an electronic endoscope or an endoscope external camera, because of the dynamic range of a solid-state imaging device such as a CCD, halation occurs if the illumination is too bright, and conversely it is too dark. It is difficult to observe.
[0003]
In general, in an imaging apparatus such as a television camera, the effective imaging luminance range is uniquely determined by the photoelectric conversion characteristics of a solid-state imaging element, for example, an imaging apparatus. That is, the lower limit of the output level of the solid-state image sensor is limited by the nozzle level. On the other hand, the upper limit of the output level is a usable operating range limited by the saturation level. In addition, since the solid-state imaging device has a constant slope of the output level characteristic, as a result, the effective imaging brightness of the solid-state imaging device is uniquely determined.
[0004]
Therefore, for example, Japanese Patent Application Laid-Open No. 57-39673 has proposed an imaging apparatus that synthesizes imaging signals with two different luminances and expands the dynamic range of the imaging signal of the solid-state imaging device.
[0005]
[Problems to be solved by the invention]
However, in imaging with an endoscope, the body cavity to be observed needs to be illuminated, the body cavity is in a wet state, and the subject has very many irregularities. As described above, the illumination is too bright at the near point, causing halation, and at the far point, the illumination is too dark to make imaging impossible. Therefore, an apparatus that simply synthesizes two types of imaging signals with different luminances and expands the dynamic range of the imaging signal of the solid-state imaging device as in the conventional example, the electronic endoscope or the endoscope Even if it is used for an endoscopic device using an external camera, this conventional device does not consider the illumination device that illuminates the subject. Therefore, there is a problem that an image cannot be taken.
[0006]
The present invention has been made in view of these circumstances, and does not cause halation at a near point, and does not cause a shortage of light at a far point. An object of the present invention is to provide an endoscope apparatus capable of observing a mirror image with a desired luminance.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an endoscope apparatus according to the present invention includes an endoscope that is inserted into a body cavity and that includes an imaging device that captures an image of a subject in the body cavity or is provided externally, and the endoscope. A light source device that supplies illumination light to the signal processing device, and a signal processing device that performs signal processing of an imaging signal from the imaging device of the endoscope and combines each image captured at a different exposure time to expand a dynamic range; A dimming signal generating device that generates a dimming signal that increases the amount of incident light from the light source device to the imaging device as compared with normal time when the signal processing device expands the dynamic range; A light amount control device that controls the amount of illumination light from the light source device based on a light control signal from the light control signal generation device is provided.
[0008]
In the endoscope apparatus according to the aspect of the invention, the dimming signal generation unit of the signal processing device generates a dimming signal so as to increase the amount of light to the imaging device when the dynamic range is expanded. It is possible to observe an endoscopic image in the body cavity with a desired luminance until it reaches a far point without causing any trouble.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0010]
1 to 7 relate to the first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of the endoscope apparatus, and FIG. 2 is a block diagram showing the configuration of the R D range expansion circuit of FIG. 3 is a diagram showing the mapping of the first LUT and the second LUT in FIG. 2, FIG. 4 is a block diagram showing the configuration of the light source device in FIG. 1, and FIG. 5 is the timing of each signal of the D range expansion circuit for R in FIG. FIG. 6 is an explanatory diagram for explaining the operation of the D range expansion circuit for R in FIG. 2, and FIG. 7 is a configuration diagram showing a configuration of a modification of the endoscope apparatus in FIG.
[0011]
(Constitution)
As shown in FIG. 1, an endoscope apparatus 1 according to the present embodiment is detachably connected to an endoscope 2 that is inserted into a body cavity and observes a subject, and an eyepiece portion of the endoscope 2. The external TV camera 4 having a CCD 3 that is a single-plate color image pickup device for picking up the subject image obtained by the mirror 2 and the CCD 3 of the external TV camera 4 are driven and controlled, and the image pickup signal from the CCD 3 is processed. Illumination light is transmitted to the endoscope 2 via a camera control unit (hereinafter referred to as CCU) 5 that displays a subject image on a monitor (not shown) and a universal cable 6 that extends from the endoscope 2 and is detachably connected. And a light source device 7 to be supplied.
[0012]
The CCU 5 includes a synchronization signal generation circuit (hereinafter referred to as SSG) 13 that generates a reference signal, a timing generator 14 that receives a reference signal from the SSG 13 and generates a drive signal and the like for the CCD 3, and a drive signal from the timing generator 14 And a CCD driver 15 for driving the CCD 3.
[0013]
The CCU 5 also outputs a preamplifier 16 that amplifies the image pickup signal from the CCD 3, a CDS circuit 17 that performs correlated double sampling (hereinafter abbreviated as CDS) based on a sampling pulse from the timing generator 14, and an output of the CDS circuit 17 as A / And an A / D converter 18 for D conversion. The image signal output from the CCD 3 is amplified by the preamplifier 16 and then dropped to the baseband by the CDS circuit 17 and converted to a digital signal by the A / D converter 18. It has come to be.
[0014]
Further, the CCU 5 separates the digital signal A / D converted by the A / D converter 18 into three color signals of RGB, and the digital signal color-separated by the color separation circuit 19. A white balance circuit 20 that performs white balance adjustment, an automatic gain control circuit (hereinafter referred to as an AGC circuit) 21 that performs gain adjustment of a digital signal whose white balance has been adjusted by the white balance circuit 20, and an AGC circuit 21. A knee & γ circuit 22 that performs knee processing and γ correction on the gain-adjusted digital signal, and an enhancement circuit that performs enhancement processing on the RGB digital signal that has been subjected to the knee processing and γ correction by the knee & γ circuit 22 via the switch 23. 26, and the enhanced digital signal is D / A converted to 75Ω And a D / A converter 28 that outputs to a monitor (not shown) via a driver 27.
[0015]
Further, the CCU 5 receives an addition average circuit 29 for averaging the digital signals of RGB subjected to the knee processing and γ correction by the knee & γ circuit 22, and inputs the output of the addition average circuit 29 via a low-pass filter (LPF) 30. An operational amplifier 33 that amplifies the difference from the reference voltage Vref input via 31 and supplies the illumination light to the endoscope 2 as a dimming signal and a dynamic range provided on the front surface of the apparatus A CPU 35 is provided which receives an input from the dynamic range expansion ON / OFF switch 34 for instructing expansion and switches the switch 23 and the switch 31 and controls the timing of the drive signal generated by the timing generator 14.
[0016]
Here, when the dynamic range expansion ON / OFF switch 34 is turned ON, each switch of the switch 23 is switched from the a side to the b side, and the RGB digital signal subjected to the knee processing and the γ correction by the knee & γ circuit 22 The D range expansion circuit 25R for R, the D range expansion circuit 25G for G, and the D range expansion circuit 25B for B are each input to the dynamic range through the control unit 23. In this case, the enhancement circuit 26 performs enhancement processing on the RGB digital signal whose dynamic range is expanded by the R D range expansion circuit 15R, the G D range expansion circuit 15G, and the B D range expansion circuit 15B. become.
[0017]
As shown in FIG. 2, the R D range expansion circuit 25R is stored in the field memory 41 and the field memory 41 for storing a digital signal for one field of the R signal subjected to the knee processing and the γ correction by the knee & γ circuit 22. The first selector 42 and the second selector 43 that switch and output the R signal and the R signal of the current field in accordance with a field discrimination signal from the timing generator 14 are provided. The second selector 43 is connected via an inverter circuit 44. Thus, an R signal in a field different from the R signal in the current field output from the first selector 42 is output.
[0018]
Also, the R D range expansion circuit 25R outputs a first look-up table (hereinafter referred to as a first lookup table) that outputs a predetermined function value to be described later with respect to the output level at the pixel rate with respect to the R signal output from the second selector 43. 1 LUT) 45, a second look-up table (hereinafter referred to as second LUT) 46, and a first multiplier 47 for multiplying the R signal output from the first selector 42 by the output at the pixel rate and the output of the first LUT 45. A second multiplier 48 that multiplies the R signal output from the second selector 43 by the output at the pixel rate and the output of the second LUT 45, the output of the first multiplier 47, and the output of the second multiplier 48. And an adder 49 that outputs the result to the enhancement circuit 26.
[0019]
The G D-range expansion circuit 25G and the B D-range expansion circuit 25B have the same circuit configuration as the R D-range expansion circuit 25R, and will not be described.
[0020]
The first LUT 45 and the second LUT 46 described above are mapped as shown in FIG. 3, and when the output level at the pixel rate of the R signal is x, the first LUT 45 is cos. ² (Px) is output and the second LUT 46 is sin. ² (Px) is output. Note that p is a correction coefficient, for example, p = (2π / 4 × 4).
[0021]
As illustrated in FIG. 4, the light source device 7 includes a lamp 51 that generates illumination light, a lamp drive circuit 52 that drives the lamp 51, and an illumination light from the lamp 51 that is inserted into the universal cable 6 via a diaphragm 53. A lens 55 that collects light at the incident end of a light guide 54 that transmits illumination light to the distal end of the endoscope 2, a motor 56 that drives the diaphragm 53, and a dimming signal from the operational amplifier 33 are input to the diaphragm. And a dimming circuit 57 for controlling 53.
[0022]
(Function)
Next, the operation of the endoscope apparatus 1 of the present embodiment configured as described above will be described.
[0023]
In the CCU 5, the CCD driver 15 drives the CCD 3 of the external TV camera 4 with the drive signal generated by the timing generator 14 based on the reference signal from the SSG 13. The photoelectric conversion signal of the subject imaged by the CCD 3 is amplified by the preamplifier 16, dropped to the baseband by the CDS circuit 17, and converted into a digital signal by the A / D converter 18.
[0024]
Thereafter, the digital signal A / D converted by the color separation circuit 19 is separated into three color signals of RGB, and the white balance adjustment, gain adjustment and knee processing and γ are performed by the white balance circuit 20, the AGC circuit 21, and the knee & γ circuit 22. After the correction, enhancement processing is performed by the enhancement circuit 26 via the switch 23, D / A conversion is performed by the D / A converter 28, and output to a monitor (not shown) via the 75Ω driver 27.
[0025]
The RGB digital signals subjected to the knee processing and the γ correction by the knee & γ circuit 22 are added and averaged by the addition averaging circuit 29 and input to the operational amplifier 33 through the LPF 30. Then, the operational amplifier 33 amplifies the difference from the reference voltage Vref input through the switch 31 and outputs the amplified signal to the dimming circuit 57 of the light source device 7 as a dimming signal.
[0026]
Here, when the dynamic range expansion ON / OFF switch 34 for instructing expansion of the dynamic range provided on the front surface of the apparatus is turned ON and the CPU 35 is instructed to expand the dynamic range, the CPU 35 switches each switch in the switch 23. Switch from the a side to the b side, and output the RGB digital signals subjected to the knee processing and the γ correction by the knee & γ circuit 22 to the R D range expansion circuit 25R, the G D range expansion circuit 25G, and the B D range expansion circuit 25B. At the same time, the timing generator 14 is controlled to switch the switch 31 from the c side to the d side.
[0027]
When the switch 31 is switched from the c side to the d side, the + side input of the operational amplifier 33 becomes the ground level, and the dimming signal that is the output of the operational amplifier 33 is at a level that opens the diaphragm 53 in the light source device 7. The dimming signal is input to the dimming circuit 57 in the light source device 7, and the dimming circuit 57 controls the motor 56 to open the diaphragm 53. As a result, the illumination light from the lamp 51 with the maximum light amount is supplied to the incident end of the light guide 54 of the endoscope 2 via the lens 55.
[0028]
Further, the timing generator 14 generates a drive signal based on the control of the CPU 35, and the CCD driver 15 uses the drive signal generated by the timing generator 14 to change the shutter time of a different time for each field, for example, the first shutter time 1 / The subject is imaged at 60 seconds, and the CCD 3 is driven so that the second shutter time is 1/4 (1/240 sec) of the first shutter time and the subject is imaged with a high-speed shutter. That is, the subject image in the A field is captured with the first shutter time, and the subject image in the B field is captured with the second shutter time. Then, as will be described later, the dynamic range is expanded by the imaging signal of the subject at the different shutter times in the R D range expansion circuit 25R, the G D range expansion circuit 25G, and the B D range expansion circuit 25B.
[0029]
Next, the details of the dynamic range expansion processing in the R range expansion circuit 25R, the G range expansion circuit 25G, and the B range D expansion circuit 25B will be described with reference to the timing chart of FIG. The circuit 25R will be described as an example.
[0030]
The dynamic range expansion ON / OFF switch 34 is turned on, the aperture 53 is in the open state, and the knee & γ circuit 22 performs the knee processing and the knee light with the maximum amount of illumination light being supplied to the incident end of the light guide 54 of the endoscope 2. The γ-corrected RGB digital signal is output to the R D range expansion circuit 25R via the switch 23.
[0031]
In the R D range expansion circuit 25R, the field determination signal (FIG. 5B) synchronized with the video signal VD (FIG. 5A) from the timing generator 14 is sent to the first selector 42 of the R D range expansion circuit 25R. The signal is output to the second selector 43 via the inverter circuit 44.
[0032]
Further, the R output of the knee & γ circuit 42 is input to one input terminal of the feed memory 41 (FIG. 5C) and the first selector 42 and the second selector 43 of the R D range expansion circuit 25R. (FIG. 5D) is input to the other input terminals of the first selector 42 and the second selector 43.
[0033]
Thereby, based on the field determination signal, the first selector 42 outputs a digital signal of the image of the A field captured in the first shutter time (1/60 sec), and the second selector 43 outputs the second shutter. The digital signal of the B field image captured in time (1/240 sec) is output.
[0034]
The digital signal of the A field image from the first selector 42 is output to the adder 49 via the first multiplier 47. On the other hand, the digital signal of the B field image from the second selector 43 is output to the first LUT (FIG. 5E), the second LUT 46 (FIG. 5F), and the second multiplier 48.
[0035]
At this time, from the first LUT 45, cos with respect to the output value x at the pixel rate of the digital signal of the B field image. ² (Px) is output to the first multiplier 47. The first multiplier 47 outputs the digital signal of the A field image at the pixel rate and the cos. ² (Px) is multiplied (FIG. 5 (g)). In addition, the second LUT 46 is configured to sin for the output value x at the pixel rate of the digital signal of the B field image. ² (Px) is output to the second multiplier 48. In this second multiplier 48, the digital signal of the B field image and the sin ² (Px) is multiplied (FIG. 5 (h)). Then, the adder 49 adds the output of the first multiplier 47 and the output of the second multiplier 48 (FIG. 5 (i)).
[0036]
In FIG. 5, for the sake of simplicity, the output of each pixel in the An field is represented by An, and the output of each pixel in the Bn field is represented by Bn, but the dynamic range in this embodiment is shown. In the enlargement processing, since the processing is performed at the pixel rate as described above, each output value at the pixel rate of the digital signal of the A field image is x and the pixel of the digital signal of the B field image is accurate. If each output value at the rate is u, the adder 49
M = xcos ² (Px) + usin ² (Px)
Will be obtained.
[0037]
The G D range expansion circuit 25G and the B D range expansion circuit 25B operate in the same manner as the R D range expansion circuit 25R, and thus the description thereof is omitted.
[0038]
(effect)
Therefore, according to the present embodiment, when the dynamic range expansion ON / OFF switch 34 is turned on in the transition from the normal observation of the observation site in the body cavity to the detailed observation, the diaphragm 53 is opened and the endoscope 2 is in the open state. In the state where the illumination light of the maximum light amount is supplied to the incident end of the light guide 54, the RGB digital signal subjected to the knee processing and the γ correction by the knee & γ circuit 22 is output to the R D range expansion circuit 25R via the switch 23. As shown in FIG. 6, the digital signal y1 of the A field image captured at the first shutter time (1/60 sec) and the digital of the B field image captured at the second shutter time (1/240 sec). Signal y ² On the other hand, the output M output from the R D range expansion circuit 15R is cos in the low luminance range. ² By the weighting by (px), it becomes a digital signal of the image of the A field mainly picked up in the first shutter time (1/60 sec). ² Since the digital signal of the B field image picked up mainly by the second shutter time (1/240 sec) is obtained by weighting with (px), the dynamic range is expanded without degrading the S / N in the low luminance region. In addition, by supplying the maximum amount of illumination light and expanding the dynamic range, it is possible to observe an endoscopic image in the body cavity with a desired luminance until reaching a far point without causing halation.
[0039]
Further, the output M can be obtained by appropriately setting p with respect to x so as to be a continuous monotonically increasing function within the brightness range until the signal imaged during the second shutter time is saturated. The image becomes uniform and an image with no sense of incongruity can be obtained.
[0040]
Here, the correction coefficient p is set to p = (2π / 4 × 4). However, the correction coefficient p is not limited to this, so that at least the output M is a monotonically increasing function with respect to x according to the characteristics of the CCD. It is possible to select. The output M is the above function, that is,
xcos ² (Px) + usin ² (Px)
However, the function is not limited to the above, and may be a function mainly including a signal picked up at a low shutter speed in a low luminance area and mainly a signal picked up at a high shutter speed in a high luminance area.
[0041]
In the present embodiment, the color separation circuit 9 performs color separation into R, G, and B signals for the R signal, G signal, and B signal, the R D range expansion circuit 25R, and the G D range expansion circuit 25G and B. Although the dynamic range is expanded by the D range expansion circuit 25B, the present invention is not limited to this, and the color separation circuit separates the luminance signal and the color difference signal to expand the dynamic range for both the luminance signal and the color difference signal or only the luminance signal. You may comprise.
[0042]
As shown in FIG. 7, in the external TV camera 4a in which the iris device 61 for controlling the amount of incident light is provided in front of the imaging surface of the CCD 3, the dynamic range expansion ON / OFF switch 34 is turned on. The CPU 35 controls the iris device 61 to the open state, so that the same operation and effect as the present embodiment can be obtained.
[0043]
In the present embodiment, the subject is imaged by the external TV camera 4 that is detachably connected to the eyepiece of the endoscope 2. However, the present invention is not limited to this. For example, a CCD is installed in the distal end of the insertion unit. Needless to say, the present embodiment can also be applied to the case where the subject is imaged by the provided electronic endoscope.
[0044]
8 to 10 relate to the second embodiment of the present invention, FIG. 8 is a block diagram showing the configuration of the endoscope apparatus, FIG. 9 is a block diagram showing the configuration of the detection circuit of FIG. 8, and FIG. It is explanatory drawing explaining an effect | action of the detection circuit of FIG.
[0045]
Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0046]
(Constitution)
As shown in FIG. 8, in this embodiment, the output of the averaging circuit 29 is output to the detection circuit 80. As shown in FIG. 9, the detection circuit 80 performs D / A conversion on the output of the addition averaging circuit 29 by a D / A converter 81, and averages it by an averaging circuit 83 via a switch 82 controlled by the CPU 35. The operational amplifier 84 amplifies the difference from the reference voltage Vref and outputs it as a dimming signal to the dimming circuit 57 of the light source device 7.
[0047]
Other configurations are the same as those of the first embodiment.
[0048]
(Function)
In the present embodiment, the switch 82 is always in the ON state under the control of the CPU 35 when the dynamic range expansion ON / OFF switch 34 is OFF, and when the dynamic range expansion ON / OFF switch 34 is turned ON, Based on the field discrimination signal (FIG. 10B) synchronized with the video signal VD (FIG. 10A) from the timing generator 14, the CPU 35 captures the B field (FIG. 10B) captured at the second shutter time (1/240 sec). 10 (c)) only the image signal (FIG. 10 (d)) is averaged by the averaging circuit 83 to generate a dimming signal (FIG. 10 (e)), so that the switch 82 is synchronized with the field discrimination signal. Turn ON / OFF.
[0049]
Other operations are the same as those in the first embodiment.
[0050]
(effect)
As described above, in the present embodiment, in addition to the effect of the first embodiment, when the dynamic range expansion ON / OFF switch 34 is turned on, B captured at a high speed, for example, the second shutter time (1/240 sec) is obtained. Since the image signal of the field is averaged and the dimming signal for the dimming circuit 57 of the light source device 7 is generated by this averaged signal, the first shutter time (1/60 sec, for example) which is likely to saturate is low. ), The endoscopic image in the body cavity up to the far point without causing halation can be obtained by high-precision light control.
[0051]
FIG. 11 is a configuration diagram showing a configuration of an endoscope apparatus according to the third embodiment of the present invention.
[0052]
Since the third embodiment is almost the same as the first embodiment, only different points will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0053]
(Constitution)
In the first embodiment, the dynamic range is expanded by the ON signal of the dynamic range expansion ON / OFF switch 34 and the dimming signal is generated by the output of the averaging circuit 29. As shown in FIG. In the present embodiment, the dynamic range is expanded based on the output state of the averaging circuit 29. Therefore, the dynamic range expansion ON / OFF switch 34 and the CPU 35 are omitted.
[0054]
Specifically, the output of the averaging circuit 29 is sampled and held by a sample and hold circuit (S / H circuit) 101, and the sampled and held signals are compared by comparators 102 and 103 with a predetermined threshold value. That is, the comparator 102 compares whether or not it is larger than a predetermined first threshold value, the comparator 102 compares whether or not it is smaller than a predetermined second threshold value, and the comparison result of the comparator 102 is sent to the high luminance pixel number counter 104. The comparison results of the comparator 103 are respectively compared with the low luminance pixel number counter 105, and the difference circuit 106 calculates the difference between the high luminance pixel number counter 104 and the low luminance pixel number counter 105 and the count value. Then, based on the result of the difference circuit 106, the D range switching determination circuit 107 switches the switch 23 and controls the timing generator 14 similarly to the CPU 35 of the first embodiment.
[0055]
Other configurations are the same as those of the first embodiment.
[0056]
(Function)
In the D range switching determination circuit 107, the difference between the count values of the high-luminance pixel number counter 104 and the low-luminance pixel number counter 105 is compared with a predetermined value close to 0, and depending on whether or not the absolute value of the difference is smaller than the predetermined value. Switch 23 is switched. That is, when the absolute value of the difference between the high luminance pixel number counter 104 and the low luminance pixel number counter 105 and the count value is close to 0, which is smaller than a predetermined value, the image is bright and dark. Since it is necessary to enlarge, the switch 23 is switched from the a side to the b side, and the RGB digital signal that has been subjected to the knee processing and the γ correction by the knee & γ circuit 22 is converted into an R D range expansion circuit 25R, a G D range expansion circuit 25G The timing generator 14 is controlled as well as being output to the B D range expansion circuit 25B.
[0057]
Other operations are the same as those in the first embodiment.
[0058]
(effect)
As described above, in the present embodiment, in the case of a bright and dark image by the D range switching determination circuit 107, the RGB digital signals are automatically converted to the R D range expansion circuit 25R, the G D range expansion circuit 25G, and the B D. Since the dynamic range expansion process is performed by outputting to the range expansion circuit 25B, an endoscopic image in the body cavity up to the far point can be obtained by high-precision light control without causing halation.
[0059]
[Appendix]
(Additional Item 1) An endoscope that is inserted into a body cavity while having an internal or external imaging device that images a subject in the body cavity;
A light source device for supplying illumination light to the endoscope;
A signal processing device that performs signal processing on an imaging signal from the imaging device of the endoscope and expands a dynamic range by synthesizing images captured at different exposure times;
When the signal processing device expands the dynamic range, a dimming signal generating device that generates a dimming signal that is increased in comparison with the amount of light incident on the imaging device from the light source device, and
A light amount control device for controlling the amount of illumination light from the light source device according to a light control signal from the light control signal generation device;
An endoscope apparatus comprising:
[0060]
(Additional Item 2) An endoscope that is inserted into a body cavity and has an internal or external imaging device that images a subject in the body cavity;
A light source device that supplies illumination light to the endoscope and that controls the amount of illumination light supplied to the endoscope by a dimming signal;
A signal processing device that performs signal processing on an imaging signal from the imaging device of the endoscope and expands a dynamic range by synthesizing images captured at different exposure times;
When the signal processing device expands the dynamic range, a dimming signal generation device that generates a dimming signal that increases the amount of light incident on the imaging device of the light source device as compared to the normal time; and
An endoscope apparatus comprising:
[0061]
(Additional Item 3) An endoscope that is inserted into a body cavity and has an internal or external imaging device that images a subject in the body cavity;
A light source device for supplying illumination light to the endoscope;
A signal processing is performed on an imaging signal from the imaging device of the endoscope, a first imaging signal obtained by imaging the subject with a first exposure time, and a second exposure that is shorter than the first exposure time. A second imaging signal that is saturated at a value higher than a light intensity level at which the first imaging signal is saturated over time, and a light intensity level until the first and second imaging signals are saturated. A first weighting processing circuit that performs a first weighting of monotonic decrease and a second weighting of monotonic increase with respect to an increase under a condition that a sum of the first and second weights is 1, and An addition circuit for adding the first and second image signals weighted by the first and second weights to the first and second imaging signals by the first and second weighting processing circuits, respectively; And adding the first and second image signals And a signal processing apparatus for expanding the dynamic range Te,
When the signal processing device expands the dynamic range, a dimming signal generation device that generates a dimming signal that increases the amount of incident light from the light source device to the imaging device as compared to normal time; and
A light amount control device for controlling the amount of illumination light from the light source device according to a light control signal from the light control signal generation device;
An endoscope apparatus comprising:
[0062]
(Additional Item 4) The endoscope apparatus according to claim 1 or 3,
The light quantity control device is a diaphragm.
[0063]
(Additional Item 5) The endoscope apparatus according to claim 2,
The device that controls the amount of incident light from the light source device to the imaging device is a diaphragm, and is controlled by a dimming signal from the dimming signal generation device.
[0064]
(Additional Item 6) The endoscope apparatus according to claim 1 or 2,
One of the images captured at different exposure times in the signal processing apparatus is an image captured at a high exposure time, and the other is an image captured at a low exposure time.
[0065]
(Additional Item 7) The endoscope apparatus according to claim 1 or 2,
The dimming signal generation device generates the dimming signal based on an image captured with a high-speed exposure time among the different exposure times when the dynamic range is expanded.
[0066]
(Additional Item 8) An endoscope having an imaging element that is inserted into a body cavity and images a subject, a light source device that supplies illumination light to the endoscope, and an image signal from the endoscope are signal-processed. In an endoscope apparatus provided with a signal processing device that synthesizes images captured at two different exposure times and expands a dynamic range,
The signal processing device is a dimming signal generating unit that generates a dimming signal that opens an aperture that controls the amount of light to the image sensor when the dynamic range is expanded.
An endoscope apparatus comprising:
[0067]
(Additional Item 9) The diaphragm is provided in the light source device.
The endoscope apparatus according to appendix 1, wherein the endoscope apparatus is characterized.
[0068]
(Additional Item 10) The endoscope is an endoscope including an external TV camera having the image pickup device detachably connected to the eyepiece unit,
The aperture is provided in an external TV camera
The endoscope apparatus according to appendix 1, wherein the endoscope apparatus is characterized.
[0069]
(Additional Item 11) At the time of expanding the dynamic range, the dimming signal generation unit generates the dimming signal based on an image picked up by a high-speed exposure time among the two different exposure times.
The endoscope apparatus according to appendix 1, wherein the endoscope apparatus is characterized.
[0070]
(Additional Item 12) An endoscope having an imaging element that is inserted into a body cavity and images a subject, a light source device that supplies illumination light to the endoscope, and an image signal from the endoscope are signal-processed. In an endoscope apparatus provided with a signal processing device that synthesizes images captured at two different exposure times and expands a dynamic range,
A high luminance part / low luminance part difference calculating means for calculating a difference between the number of pixels of the high luminance part and the low luminance part from an imaging signal from the endoscope;
Dynamic range expansion control means for controlling the dynamic range expansion processing based on the calculation result of the high luminance part / low luminance part difference calculating means;
An endoscope apparatus comprising:
[0071]
【The invention's effect】
As described above, according to the endoscope apparatus of the present invention, no halation occurs at the near point, and there is no shortage of light at the far point. This has the effect that the endoscopic image can be observed with a desired luminance.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus according to a first embodiment of the present invention.
2 is a block diagram showing the configuration of an R range expansion circuit for R in FIG. 1;
FIG. 3 is a diagram illustrating mapping of the first LUT and the second LUT in FIG. 2;
4 is a configuration diagram showing the configuration of the light source device of FIG. 1;
FIG. 5 is a timing chart showing the timing of each signal in the R D range expansion circuit of FIG. 2;
6 is an explanatory diagram for explaining the operation of the D range expansion circuit for R in FIG. 2; FIG.
7 is a configuration diagram showing a configuration of a modified example of the endoscope apparatus of FIG. 1. FIG.
FIG. 8 is a configuration diagram showing a configuration of an endoscope apparatus according to a second embodiment of the present invention.
9 is a configuration diagram showing the configuration of the detection circuit of FIG. 8;
10 is an explanatory diagram for explaining the operation of the detection circuit of FIG. 9;
FIG. 11 is a configuration diagram showing a configuration of an endoscope apparatus according to a third embodiment of the present invention.
[Explanation of symbols]
1. Endoscope device
2. Endoscope
3 ... CCD
4 ... External TV camera
5 ... CCU
6 ... Universal cable
7. Light source device
13 ... SSG
14 ... Timing generator
15 ... CCD driver
16 ... Preamplifier
17 ... CDS circuit
18 ... A / D converter
19. Color separation circuit
20 ... White balance circuit
21 ... AGC circuit
22 ... knee & γ circuit
23, 31 ... switch
25R ... D range expansion circuit for R
25G ... D range expansion circuit for G
25B ... D range expansion circuit for B
26 ... Enhanced circuit
27 ... 75Ω driver
28 ... D / A converter
29 ... Addition averaging circuit
30 ... LPF
33. Operational amplifier
34 ... Dynamic range expansion ON / OFF switch
35 ... CPU
41 ... Field memory
42. First selector
43 ... Second selector
44 ... Inverter circuit
45 ... 1st LUT
46 ... Second LUT
47. First multiplier
48 ... second multiplier
49 ... Adder
51 ... Ramp
52. Lamp driving circuit
53 ... Aperture
54 ... Light guide
55 ... Lens
56 ... Motor
57. Light control circuit

Claims (1)

An endoscope that is inserted into a body cavity and that has an internal or external imaging device that images a subject in the body cavity;
A light source device for supplying illumination light to the endoscope;
A signal processing device that performs signal processing on an imaging signal from the imaging device of the endoscope and expands a dynamic range by synthesizing images captured at different exposure times;
When the signal processing device expands the dynamic range, a dimming signal generation device that generates a dimming signal that increases the amount of incident light from the light source device to the imaging device as compared to normal time; and
A light amount control device for controlling the amount of illumination light from the light source device according to a light control signal from the light control signal generation device;
An endoscope apparatus comprising:

Images