JP2004289389A - Electronic image pickup device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic image pickup device and a method used for a microscope capable of obtaining a photographing image with excellent quality having no substrate unevenness. <P>SOLUTION: The electronic image pickup device has an image pickup element provided with a photo-electric converting element which generates the electric charges corresponding to a light amount of a observation image and which is arranged two-dimensionally, a vertical transfer path for transferring the electric charges of the photo-electric converting element in the vertical direction, and a horizontal transfer path for transferring the electric charges transferred via the vertical transfer path in the horizontal direction. Discharge operation of unwanted electric charges is executed by making the driving speed of the electric charges, which are transferred in the vertical transfer path by a transfer pulse VCCD, higher than the normal speed immediately before transferring the electric charges of the photo-electric converting element as image signals to the vertical transfer path by an electric charge transfer pulse TG. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic imaging device and a method for capturing an observation image of a microscope with a solid-state imaging device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, an image of a subject formed by a photographing lens is imaged by an imaging means such as a solid-state imaging device (hereinafter, referred to as a CCD), and an image signal obtained as an electric signal from the imaging means is electronically recorded. 2. Description of the Related Art Electronic imaging devices such as electronic cameras have been increasingly used.
[0003]
In such an electronic imaging device, a digital camera (still image camera) used particularly for still image shooting is becoming comparable to a silver halide camera.
[0004]
By the way, the functional requirements of a still image camera are diverse, and the exposure control during imaging is of particular importance, and the various exposure functions achieved in a silver halide camera are at almost the same level. Up to.
[0005]
Further, functions that cannot be realized by a silver halide camera are also realized. For example, a so-called electronic shutter realized by controlling charge accumulation in a CCD cannot be realized by a mechanical shutter of a normal silver halide camera. It can be realized up to a high-speed electronic shutter.
[0006]
However, on the other hand, there are also problems such as image quality deterioration due to the CCD, and digital cameras have been put to practical use by making various efforts to prevent them from becoming apparent.
[0007]
As a typical example of such a defect, a smear phenomenon is known.
[0008]
This phenomenon is, to be precise, a phenomenon that occurs comprehensively due to smearing and grooming, but is simply referred to as smearing here in accordance with the common use of those skilled in the art.
[0009]
Smear is caused by reading charges through a vertical transfer path. In other words, the vertical transfer path is designed to be completely shielded from light and not affected by incident light. However, in reality, incomplete light shielding at the boundary, mixing of light due to diffraction components and multiple reflections, and Due to imperfections, slight mixing of light is inevitable. For this reason, when an intense light spot is continuously incident, the charge transferred from the charge storage region to the vertical transfer path is affected. It also affects the charge transferred. In other words, due to the influence on the charges transferred in the vertical transfer, streak-like light extending in the vertical direction on the image is generated as smear, which significantly impairs the image quality.
[0010]
As a method of reducing such smear, it is known to correct an acquired image signal, use an optical shutter, and the like.
[0011]
However, since the method of correcting an image signal is a method of performing post-processing, it is not a fundamental solution for smear reduction. However, as a method using an optical shutter, the following method is considered. I have.
[0012]
First, the CCD will be briefly described.
[0013]
FIG. 12 is a plan view showing a CCD element structure, for example, a vertical overflow drain structure of an interline progressive scan type. In this case, photodiodes 201 serving as photoelectric conversion elements are two-dimensionally arranged, and a plurality of vertical photodiodes are arranged in a column direction via a read gate (not shown) for transferring electric charges accumulated in the photodiodes 201. A vertical CCD 202 as a transfer path is arranged, and a horizontal CCD 203 as one horizontal transfer path is arranged in a row direction at an end of the vertical CCD 202. Then, the electric charges accumulated in the photodiode 201 are read out to the vertical CCD 202 by the electric charge transfer pulse TG, and are transferred in the vertical CCD 202 downward in the drawing by the transfer pulse VCCD. The signal charges transferred from the vertical CCD 202 are transferred to a horizontal CCD 203, transferred to the horizontal CCD 203 in the left direction on the paper, and finally output to the outside via a readout amplifier 204.
[0014]
Such a CCD is driven according to a timing chart shown in FIG.
[0015]
In this case, the vertical synchronization signal VD shown in FIG. 3A is output at one frame period, and the horizontal synchronization signal HD shown in FIG. 3B is output line by line. In addition, the charge transfer pulse TG shown in FIG. 3C is output for each frame, and charges accumulated in the photodiode 201 are read out to the vertical CCD 202. The transfer pulse VCCD shown in FIG. 4D is configured to transfer the electric charge in the vertical CCD 202 in synchronization with the horizontal synchronization signal HD. Further, a charge discharge pulse VSUB shown in FIG. 3E is output in multiple pulses (cycles of V transfer pulses) in synchronization with the charge transfer pulse TG, and the charge accumulated in the photodiode 201 is transferred by the first one pulse to the semiconductor substrate. (Substrate = vertical overflow drain VOFD), and exposure is started from the last one pulse. The exposure time is defined from the last one pulse of the charge discharge pulse VSUB to the next charge transfer pulse TG, and the charge read from the photodiode 201 at the timing of the charge transfer pulse TG is transferred by the transfer pulse VCCD. A signal output (image signal) SIG is read by being transferred inside the vertical CCD 202.
[0016]
FIG. 11F shows the state of the opening / closing operation of the mechanical shutter, and FIG. 10G shows the signal output (image signal) SIG output together with the transfer pulse VCCD at the timing of the charge transfer pulse TG. Indicates the state of the memory recording operation.
[0017]
When a still image trigger capture command (timing t0) is issued in this state, the final output pulse related to exposure is significant in terms of timing, so that the charge discharge pulse VSUB has sufficient charge discharge and potential stabilization in the element. From the balance, driving at a known H rate (outputting a short-time pulse of a predetermined width during each horizontal blanking period) is performed. Exposure is started at time t1 when the charge discharge pulse VSUB indicated by the thick line in the drawing is output.
[0018]
On the other hand, the transfer pulse VCCD continuously performs high-speed driving for discharging unnecessary charges transferred in the vertical CCD 202 from an appropriate time before the start of exposure. This high-speed driving is different from the driving speed of the electric charges transferred in the vertical CCD 202, and is continuously performed at a speed several times to several tens times the normal driving speed, and is transferred from the photodiode 201 in the vertical CCD 202. The charge including the smear cause is discharged at high speed as unnecessary charge. This unnecessary charge discharging operation is continued until just before the time t2 when the exposure is completed.
[0019]
Here, the high-speed drive speed of the transfer pulse VCCD is required to be at least 1 / X in one frame period, where X is a multiple of the normal drive speed (defined as the inverse ratio of the time required to transfer one screen). .
[0020]
Thereafter, at time t2, when the charge transfer pulse TG shown in FIG. 9C is output, the exposure is completed, and at the same time, the charge is read out from the photodiode 201 as an image signal at the timing of the charge transfer pulse TG. Immediately before this, the mechanical shutter is closed as shown in FIG. 3 (f), and thereafter, charges are transferred into the vertical CCD 202 by the transfer pulse VCCD, and the signal output SIG is read.
[0021]
In this case, the mechanical shutter is closed to forcibly prevent light from being incident on the photodiode 201, thereby eliminating the cause of smear on the charges transferred in the vertical CCD 202.
[0022]
However, closing the mechanical shutter requires a delay time dt of about several hundred microseconds to several milliseconds. Therefore, the reading of the signal output SIG by the transfer pulse VCCD cannot be started during the period corresponding to the delay time dt. Then, the reading of the signal output SIG by the normal drive is started from the time when the mechanical shutter is closed, actually, from the time t3 including a margin in consideration of a variation element of the operation and the like. In this case, the mechanical shutter is kept closed until reading is completed after at least one frame period.
[0023]
In this way, the cause of the smear can be removed, so that a good quality image can be obtained. In addition, since the charge accumulation time is completely electronically controlled, there is no influence from variations in the mechanical shutter and the like. In addition, it is possible to realize a high-speed shutter that cannot be realized by a mechanical shutter of a normal silver halide camera.
[0024]
Such a technique is disclosed in Patent Document 1, for example.
[0025]
[Patent Document 1]
JP-A-10-191170
[0026]
[Problems to be solved by the invention]
However, in the case of using a mechanical shutter as described above, control is complicated in terms of the configuration, and a control circuit for opening and closing the mechanical shutter is required. It will be expensive.
[0027]
Further, for example, in the case of continuous shooting in which a plurality of still images are captured by a single still image capturing command as shown in FIG. 14, the charge transfer pulse TG is generated as shown in FIG. Each time the exposure is completed, the mechanical shutter shown in FIG. 1F is closed before the signal output SIG is read out, and the closing operation of the mechanical shutter is performed for several hundred microseconds to several milliseconds every time the mechanical shutter is closed. Since the delay time dt is required, there is also a problem that the shooting time required for continuous shooting becomes long.
[0028]
By the way, recently, a CCD has been used instead of a conventional silver halide camera for an image pickup apparatus for picking up an image observed by a microscope.
[0029]
Such a CCD for a microscope often captures a special observation image in which a dark portion such as a sample is scattered in uniform high-luminance light, unlike a subject such as a general camera. .
[0030]
For this reason, as described above, it is considered that the vertical streak-like smear that occurs when the intense spot light continuously enters is unlikely to occur, and there is no need for a means for preventing the occurrence of smear. It is considered.
[0031]
However, when an image of a microscope image is actually taken, unlike a vertical smear that extends up and down, which occurs in the case of a spot light, a background unevenness such as noise on a dark portion such as a sample is smeared. Occurs, and the background unevenness noise causes deterioration of the captured image. The background unevenness noise due to the smear is conspicuous in a dark part, which is considered to be due to a high gain in a dark part in a γ curve of image processing.
[0032]
With a general camera, when shooting a high-brightness subject, it is difficult to shoot dark areas due to lens flare, etc.In addition, vertical streak-like smears extending up and down are conspicuous, so there is no problem with background unevenness noise in smears Was.
[0033]
In the case of a microscope, since it is easy to capture an image having a difference in light and shade without a flare, the unevenness of the background is conspicuous, and the unevenness of the background is the same level in RGB. (For example, the B gain is high), thereby causing a further problem.
[0034]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an electronic imaging apparatus and method used for a microscope capable of acquiring a high-quality captured image without unevenness of the background.
[0035]
[Means for Solving the Problems]
The invention according to claim 1 is an electronic imaging apparatus that captures an observation image of a microscope, wherein the two-dimensionally arranged photoelectric conversion elements that generate electric charges according to the light amount of the observation image, A vertical transfer path for transferring charges in a vertical direction, and an image pickup device including a horizontal transfer path for transferring the charges transferred via the vertical transfer path in a horizontal direction, and charges the photoelectric conversion element. Immediately before the image signal is transferred to the vertical transfer path, the driving speed of the charges transferred in the vertical transfer path is higher than the normal speed, and an unnecessary charge discharging operation is performed.
[0036]
According to a second aspect of the present invention, in the first aspect of the present invention, the image pickup device can further set an exposure time for controlling a light amount incident on the photoelectric conversion unit, and the unnecessary charge of the unnecessary charge is set in accordance with the exposure time. It is characterized in that the presence or absence of a discharging operation is determined.
[0037]
According to a third aspect of the present invention, in the first aspect of the present invention, a displacing means for displacing a relative position of the observation image and an image pickup device for picking up the observation image, and the observation image displaced by the displacement means And reading means for reading out from the image pickup device image signals respectively obtained corresponding to the relative positions of the image pickup device.
[0038]
According to a fourth aspect of the present invention, in the third aspect of the present invention, the unnecessary charge is discharged from the image signal read from the image sensor by the reading means.
[0039]
The invention according to claim 5, wherein the two-dimensionally arranged photoelectric conversion elements that generate charges according to the amount of light of the observation image, a vertical transfer path that transfers the charges of the photoelectric conversion elements in a vertical direction, An electronic imaging method for capturing an observation image of a microscope having an image sensor having a horizontal transfer path for transferring the charge transferred via a transfer path in a horizontal direction, wherein the charge of the photoelectric conversion element is imaged. Immediately before the signal is transferred to the vertical transfer path, the driving speed of the charges transferred in the vertical transfer path is set higher than the normal speed, and an unnecessary charge discharging operation is performed.
[0040]
As a result, according to the present invention, noise on the entire captured image can be removed, and a high-quality captured image without unevenness (smear) can be obtained.
[0041]
Further, according to the present invention, it is possible to prevent the power consumption and the photographing time from being unnecessarily increased.
[0042]
Further, according to the present invention, even when pixel shift is employed, noise on the entire captured image can be removed, and a high-quality captured image free from unevenness of the background (smear) can be obtained.
[0043]
Still further, according to the present invention, even when a CCD for interlaced reading is employed, noise on the entire captured image can be removed, and a high-quality captured image without unevenness (smear) can be obtained. it can.
[0044]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0045]
(First Embodiment)
FIG. 1 shows a schematic configuration of a microscope to which the present invention is applied.
[0046]
In FIG. 1, reference numeral 1 denotes a microscope main body, on which an objective lens 4 facing a sample 3 on a stage 2 is arranged. An eyepiece unit 6 is disposed on the observation optical axis via the objective lens 4 via a trinocular tube unit 5, and an electronic imaging device 8 of the present invention via an imaging lens unit 7. Is arranged.
[0047]
FIG. 2 is a block diagram illustrating a schematic configuration of the electronic imaging device 8 used in the above-described microscope.
[0048]
In FIG. 2, reference numeral 11 denotes a CCD, on which an optical observation image of the above-described sample 3 is formed via a photographing optical system 12 and a light shielding filter 13.
[0049]
Here, the photographic optical system 12 includes a photographic lens, a drive motor for driving the photographic lens, and a drive mechanism. The light shielding filter 13 is for shielding the optical system from light.
[0050]
The CCD 11 photoelectrically converts an optical observation image formed on an imaging surface to generate an image signal. The element structure of the CCD 11 here is the same as that described with reference to FIG.
[0051]
The CCD 11 is connected to a timing generator (TG) 14 and a signal generator (SG) 15 for generating a synchronization signal such as a driving pulse, and is driven by a predetermined timing signal. The CCD 11 has an electronic shutter function (means) (not shown) so that the exposure time can be controlled.
[0052]
The CCD 11 is connected to a CDS circuit (correlated double sampling circuit) 16. The CDS circuit 16 extracts an image signal component from an output signal of the CCD 11.
[0053]
An amplifier (AMP) 17 is connected to the CDS circuit 16 as gain adjustment means. The amplifier (AMP) 17 is composed of gain control means including an AGC circuit for adjusting the output signal level from the CDS circuit 16 to a predetermined gain value.
[0054]
An image memory 19 is connected to the amplifier (AMP) 17 via an A / D converter 18. The A / D converter 18 converts an analog image signal output from the amplifier (AMP) 17 into a digital image signal in synchronization with a timing signal of the timing generator (TG) 14. The image memory 19 stores a digital signal output from the A / D converter 18, and the reading and writing of data is controlled by the memory controller 20.
[0055]
An image signal processing circuit 21 is connected to the image memory 19. The image signal processing circuit 21 performs image signal processing such as γ correction and edge enhancement of the image signal stored in the image memory 19.
[0056]
The image signal processing circuit 21 is connected to a liquid crystal display (LCD) 22 and a DRAM 23 as display means. The liquid crystal display (LCD) 22 has a signal processing circuit for processing the image signal into a displayable form, and displays the signal-processed image here. The DRAM 23 is a camera built-in storage unit including a memory for temporarily storing image signals.
[0057]
The DRAM 23 is connected to a compression / expansion circuit 24 that performs compression processing and expansion processing on the image signal.
[0058]
The components described above are connected to the CPU 25 as control means. The CPU 25 controls the entire electronic imaging device 8 as a whole.
[0059]
The recording medium 26 and the operation unit 27 are connected to the CPU 25. The recording medium 26 includes a memory card for storing image signals. The operation unit 27 includes various operation switches such as a switch for starting an AF operation at the time of photographing and generating a trigger signal for starting an exposure operation.
[0060]
An operation performed at the time of photographing in the electronic imaging device configured as described above will be described. Here, only the part related to the present invention among the operations performed at the time of photographing is described.
[0061]
The image signal component obtained by the CCD 11 is extracted by a CDS circuit 16, the output signal level is adjusted to a predetermined gain value by an amplifier (AMP) 17, and then converted to a digital signal by an A / D converter 18. Is converted. Then, one frame of the image signal converted into the digital signal is temporarily stored in the image memory 19.
[0062]
Thereafter, the image signal stored in the image memory 19 is read out, subjected to image signal processing such as γ correction and edge enhancement in the image signal processing circuit 21 and output to the LCD 22 to perform image reproduction and display processing. .
[0063]
FIG. 3 is a timing chart for explaining the operation of the first embodiment. Here, the description of the same parts as in FIG. 13 will be omitted, and only different parts will be described.
[0064]
Also in this case, the transfer pulse VCCD shown in FIG. 3D transfers the charges in the vertical CCD 202 (see FIG. 12) in synchronization with the horizontal synchronization signal HD. Also, a charge discharge pulse VSUB shown in FIG. 3E is output by a plurality of pulses (cycles of the V transfer pulse) in synchronization with the charge transfer pulse TG, and the accumulated charge of the photodiode 201 is converted to the semiconductor substrate by the first pulse. And exposure is started from the last one pulse. The exposure time is defined from the last one pulse of the charge discharge pulse VSUB to the next charge transfer pulse TG, and the charge read from the photodiode 201 at the timing of the charge transfer pulse TG is transferred by the transfer pulse VCCD. A signal output (image signal) SIG is read by being transferred inside the vertical CCD 202.
[0065]
In this state, when a still image trigger capture command is issued at time t0, exposure is started at time t1 at which the charge discharge pulse VSUB indicated by a thick line in the drawing is output.
[0066]
On the other hand, the transfer pulse VCCD continuously performs high-speed driving for discharging unnecessary charges transferred to the vertical CCD 202 (see FIG. 12) from an appropriate time before the start of exposure. The high-speed driving is different from the driving speed of the electric charges transferred in the vertical CCD 202 and is continuously performed at a high speed several times to several tens times the normal driving speed. This operation is continued until immediately before time t2, which is the timing of the end of exposure.
[0067]
Thereafter, at time t2, when the charge transfer pulse TG shown in FIG. 9C is output, the exposure is completed, and at the same time, the charge of the image signal is read from the photodiode 201 at the timing of the charge transfer pulse TG. Causes the charge to be transferred into the vertical CCD 202 by the transfer pulse VCCD, and the signal output (image signal) SIG is read.
[0068]
That is, in the first embodiment, unnecessary charges transferred to the vertical CCD 202 are forcibly discharged by the high-speed driving of the transfer pulse VCCD shown in FIG. 4D, and thereafter, the charges shown in FIG. When the transfer pulse TG is output, charges are read from the photodiode 201 at the timing of the charge transfer pulse TG without closing the mechanical shutter.
[0069]
In this way, when the transfer pulse VCCD is continuously driven at a high speed and the unnecessary charge transferred to the vertical CCD 202 is forcibly discharged from the appropriate time before the start of the exposure, the discharge operation alone is performed. It was confirmed that the noise on the whole could be removed, and the unevenness of the background noise could be greatly reduced.
[0070]
Therefore, in this way, the noise on the entire captured image can be removed only by continuously performing the high-speed drive of the transfer pulse VCCD from before the start of the exposure, and a high-quality captured image without unevenness (smear) can be obtained. Can be obtained. In addition, since a mechanical shutter is not used, control can be simplified in terms of configuration as compared with a conventional mechanism using a mechanical shutter, and a control circuit for opening and closing the mechanical shutter can be eliminated, thereby simplifying the overall configuration of the CCD. And can be inexpensive.
[0071]
Furthermore, for example, in the case of continuous shooting in which a plurality of still images are captured by a single still image capturing command as shown in FIG. 4, high-speed driving of the transfer pulse VCCD shown in FIG. After the high-speed discharge, a charge transfer pulse TG is output as shown in FIG. 3C, and immediately after the exposure time is over, the signal output (image signal) SIG shown in FIG. Therefore, the effect of the delay time when the conventional mechanical shutter is closed can be eliminated, and the time for continuous shooting can be greatly reduced.
[0072]
(Second embodiment)
Next, a second embodiment will be described.
[0073]
The schematic configuration of the electronic imaging apparatus according to the second embodiment is the same as that of FIG. 2 described in the first embodiment, and the drawing is used.
[0074]
By the way, the operation of discharging unnecessary charges by the high-speed driving of the transfer pulse VCCD consumes a large amount of power and may increase the shooting time. On the other hand, it is known that the exposure time affects the occurrence of background unevenness noise, and the longer the exposure time, the lower the background unevenness noise.
[0075]
Therefore, in the second embodiment, the presence or absence of an unnecessary charge discharging operation is determined according to the exposure time for controlling the amount of light incident on the CCD. Here, only when the exposure time is short, the operation of discharging unnecessary charges by high-speed driving of the transfer pulse VCCD is performed.
[0076]
In this case, FIG. 5 is a timing chart for explaining the operation of the second embodiment. Here, the description of the same parts as in FIG. 3 will be omitted, and only different parts will be described.
[0077]
In this case, FIG. 5F shows an exposure time flag. The exposure time flag outputs an H level when the exposure time is short (for example, 1/1000), and outputs an L level when the exposure time is long.
[0078]
Therefore, if the exposure time is short and the exposure time flag is at the H level, unnecessary charges are discharged at high speed by the high-speed driving of the transfer pulse VCCD shown in FIG. The high-speed drive of the transfer pulse VCCD shown in FIG.
[0079]
In this way, it is possible to prevent an unnecessary increase in power consumption and an increase in the photographing time, and it is possible to obtain a high-quality image in which unevenness noise caused by smear is reduced.
[0080]
(Third embodiment)
Next, a third embodiment will be described.
[0081]
The schematic configuration of the electronic imaging apparatus according to the third embodiment is the same as that of FIG. 2 described in the first embodiment, and thus the drawing is used.
[0082]
By the way, in an electronic imaging device, it is important to display a better image on the display means. For this reason, the pixels of the subject image formed on the image sensor are shifted, and a plurality of images shifted by the pixels are shifted. Is read, and a plurality of images are combined to obtain a high-definition still image.
[0083]
The third embodiment is an electronic image pickup apparatus capable of such a pixel shift. In FIG. 2, a piezoelectric driver 31 is further connected to the CCD 11 as displacement means. The piezoelectric driver 31 has a piezoelectric element such as a piezo element, and the CCD 11 is periodically displaced by the piezoelectric element to output an image signal in which the subject image at each displacement position is shifted by a pixel. ing.
[0084]
Further, the image memory 19 includes memories corresponding to a plurality of images obtained by shifting the pixels, and stores each image separately in these memories. Then, based on the control of the CPU 25, the plurality of images are rearranged into one image.
[0085]
Others are the same as FIG.
[0086]
An operation performed at the time of photographing in the electronic imaging device configured as described above will be described. Here, only the part related to the present invention among the operations performed at the time of photographing is described.
[0087]
In this case, the CCD 11 is vibrated at a constant period by a piezoelectric driver 31 having a piezoelectric element such as a piezo element, and generates an imaging output in synchronization with the vibration. For example, in the pixel arrangement shown in FIG. 6 (a), (1) → (2) → (3) → (4) at a 2/3 pixel interval from the reference pixel position (1) shown in FIG. 6 (b). In the order of ▼ → ▲ 5 ▼ → ▲ 6 ▼ → ▲ 7 ▼ → ▲ 8 ▼ → ▲ 9, three pixels are shifted in the horizontal and vertical directions respectively, for a total of 9 pixels, and the image of each displacement position is taken. Generate output. As a result, the number of pixels in the X and Y directions is tripled without changing the R, G, and B color arrangements as shown in FIG.
[0088]
An image signal component of the image signal obtained by the CCD 11 is extracted by a CDS circuit 16, the output signal level is adjusted to a predetermined gain value by an amplifier (AMP) 17, and then converted to a digital signal by an A / D converter 18. Is converted. Then, the image signal converted into the digital signal is temporarily stored in the image memory 19.
[0089]
The image memory 19 has memories corresponding to the nine images (1) to (9) obtained by shifting the pixels, and stores the nine images individually in these memories. Then, based on the control of the CPU 25, these nine images are rearranged into one image.
[0090]
Thereafter, the image signal of the rearranged image is read out, subjected to image signal processing such as γ correction and edge enhancement in the image signal processing circuit 21, output to the LCD 22, and subjected to image reproduction and display processing.
[0091]
Such an electronic imaging device is driven according to a timing chart shown in FIG. In this case, the vertical synchronization signal VD shown in FIG. 3A is output at one frame period, and the horizontal synchronization signal HD shown in FIG. 3B is output line by line. The charge transfer pulse TG shown in FIG. 9C is output for each frame, and charges are read out from the photodiode 201 of the CCD shown in FIG. The VCCD transfer pulse shown in FIG. 3D transfers charges in the vertical CCD 202 in synchronization with the horizontal synchronization signal HD. Further, the charge discharge pulse VSUB shown in FIG. 3E is output by a plurality of pulses (the period of the V transfer pulse) in synchronization with the charge transfer pulse TG. The charge discharge pulse VSUB discharges the accumulated charge of the photodiode 201 to the semiconductor substrate in the first one pulse, and starts exposure from the last one pulse. The exposure time is defined from the last one pulse of the charge discharge pulse VSUB to the next charge transfer pulse TG, and the charge read from the photodiode 201 at the timing of the charge transfer pulse TG is transferred by the transfer pulse VCCD. A signal output (image signal) SIG is read by being transferred inside the vertical CCD 202.
[0092]
However, in this case, if the pixel shift is performed for each frame, the exposure is also performed at the timing of the pixel shift (image shift) ((f) in the figure), but the pixel moves during the pixel shift. Therefore, the image signal obtained after the exposure time may be blurred, and cannot be used for image synthesis. Therefore, as shown in FIG. 3G, the signal output SIG obtained by exposure at the same timing as the pixel shift (image shift) in the first frame is not used, and the pixel shift (image shift) in the next frame. Only the signal output SIG obtained by the exposure when not performing is stored as an effective image signal in the memory at the timing shown in FIG. That is, of the two frames, the image signal acquired by the exposure in the first frame in which the pixel shift (image shift) is performed is not adopted, and the exposure in the next frame in which the pixel shift (image shift) is not performed is performed. Only the signal output (image signal) SIG obtained by the above is adopted.
[0093]
Also in this case, the transfer pulse VCCD shown in FIG. 3D is continuously driven at a high speed before the start of exposure in a frame in which no pixel shift (image shift) is performed. The high-speed driving is different from the driving speed of the electric charges transferred in the vertical CCD 202 and is continuously performed at a high speed several times to several tens times the normal driving speed. This operation is continued until immediately before time t2, which is the timing of the end of exposure.
[0094]
Thereafter, when the charge transfer pulse TG shown in FIG. 3C is output, the exposure is completed, and at the same time, the charge of the image signal is read from the photodiode 201 at the timing of the charge transfer pulse TG. The charge is transferred into the vertical CCD 202 by the VCCD, and the signal output (image signal) SIG is read.
[0095]
Therefore, even in the electronic imaging apparatus employing such a pixel shift, an operation of continuously performing the high-speed drive of the transfer pulse VCCD only before the start of exposure in a frame in which the pixel shift (image shift) is not performed is performed. Noise on the entire captured image can be removed, and a high-quality captured image without unevenness (smear) can be obtained.
[0096]
Of course, in the third embodiment, the same effects as those in the first embodiment can be expected.
[0097]
(Fourth embodiment)
Next, a fourth embodiment will be described.
[0098]
The schematic configuration of the electronic imaging apparatus according to the fourth embodiment is the same as that of FIG. 2 described in the third embodiment, so that FIG.
[0099]
The fourth embodiment is characterized in that the frame period is substantially lengthened by the period from the start to the end of the pixel shift (image shift).
[0100]
FIG. 8 is a timing chart for explaining the operation of the fourth embodiment. Here, the description of the same parts as in FIG. 7 will be omitted, and only different parts will be described in detail.
[0101]
In this case, as shown in FIG. 8A, the vertical synchronizing signal VD is obtained by inserting one vertical synchronizing signal VD ′ having a short pulse width after the normal vertical synchronizing signal VD. The indicated charge transfer pulse TG is output at the rise of the normal vertical synchronization signal VD, and the frame period is substantially extended by + α for the period from the start to the end of the pixel shift (image shift). .
[0102]
In this case, as shown in FIG. 8E, the charge discharge pulse VSUB is output at the cycle of the V transfer pulse in synchronization with the charge transfer pulse TG, and the pixel shift (image shift) shown in FIG. During the operation, the exposure is not performed.
[0103]
Then, the high-speed driving of the transfer pulse VCCD shown in FIG. 4D is continuously performed from the rising point of the vertical synchronizing signal VD 'before the start of the exposure in which the pixel shift (image shift) is not performed. This operation is continued until the timing of the end of the exposure. When the charge transfer pulse TG shown in FIG. 9C is output, the exposure is completed and the signal output (image signal) SIG is read.
[0104]
Accordingly, even in this case, the entire captured image is operated only by continuously performing the high-speed drive of the transfer pulse VCCD from the rising point of the vertical synchronizing signal VD 'before the start of the exposure in which no pixel shift (image shift) is performed. It is possible to remove noise on the image and obtain a high quality captured image without unevenness (smear).
[0105]
Of course, in the fourth embodiment, the same effect as in the first embodiment can be expected.
[0106]
(Fifth embodiment)
Next, a fifth embodiment will be described.
[0107]
The schematic configuration of the electronic imaging apparatus according to the fifth embodiment is the same as that of FIG. 2 described in the third embodiment, so that FIG.
[0108]
By the way, recently, there has been a remarkable increase in the density of CCDs, and accordingly, CCDs for interlaced reading have been used.
[0109]
The sixth embodiment is characterized in that an interlace readout CCD is used as the CCD 11.
[0110]
FIG. 9 shows an element structure of a CCD for interlace reading, and the same parts as those in FIG. 12 described above are denoted by the same reference numerals. In this case, a photodiode 201a for the A field and a photodiode 201b for the B field are set as a light receiving element, and these sets are arranged in a matrix. The signal charge stored in the photodiode 201a for the A field is read out to the vertical CCD 202 by the charge transfer pulse TG1, and the signal charge stored in the photodiode 201a for the B field is changed to the charge transfer pulse TG2. Is read out by the vertical CCD 202, and is transferred in the vertical CCD 202 downward in the drawing. The signal charges transferred from the vertical CCD 202 are transferred to a horizontal CCD 203, transferred to the horizontal CCD 203 in the left direction on the paper, and finally output to the outside via a readout amplifier 204.
[0111]
FIG. 10 is a timing chart for explaining the operation of this embodiment. Here, the description of the same parts as in FIG. 7 will be omitted, and only different parts will be described in detail.
[0112]
In this case, the pixel shift (image shift) shown in FIG. 11F is performed for each field between frames. The vertical synchronization signal VD shown in FIG. 11A is output at the illustrated period, and the charge transfer pulses TGA and TGB shown at FIGS. 10C and 10C ′ are output at the illustrated period.
[0113]
In this case, when a trigger is given and the first charge transfer pulse TGB is issued, the charges in the photodiodes 201a and 201b are discharged to the substrate side by the first pulse of the charge discharge pulse VSUB synchronized with the charge transfer pulse TGB. The exposure time A is from the last one pulse to the charge transfer pulse TGA, an image signal is output at the timing of the charge transfer pulse TGA, and the charge discharge pulse VSUB is also synchronized with the charge transfer pulse TGA. The charges in the photodiodes 201a and 201b are discharged to the substrate side by the first one pulse, and an exposure time B is set from the last one pulse to the first charge transfer pulse TGB of the next field, and this charge transfer pulse TGB is used. The image signal is output also at the timing of.
[0114]
Also in this case, the transfer pulse VCCD shown in FIG. 9D is continuously driven at a high speed from an appropriate time before the start of exposure in which no pixel shift (image shift) is performed. This operation is continued until the charge transfer pulse TGA shown in FIG. 10C or the charge transfer pulse TGB shown in FIG. 10C ′ at the exposure end timing is output, and the charge transfer pulse TGA (TGB) is output. Then, the exposure is completed, and the signal output (image signal) SIG is read.
[0115]
Therefore, even in an electronic imaging apparatus employing such an interlaced readout CCD, the operation of continuously performing the high-speed drive of the transfer pulse VCCD only before the start of exposure in which no pixel shift (image shift) is performed is performed. Noise on the entire captured image can be removed, and a high-quality captured image without unevenness (smear) can be obtained.
[0116]
Of course, in the third embodiment, the same effects as those in the first embodiment can be expected.
[0117]
(Sixth embodiment)
Next, a sixth embodiment will be described.
[0118]
The schematic configuration of the electronic imaging apparatus according to the sixth embodiment is the same as that of FIG. 2 described in the third embodiment, so that FIG.
[0119]
The sixth embodiment is characterized in that the photographing time can be reduced.
[0120]
FIG. 11 is a timing chart for explaining the operation of this embodiment. Here, the description of the same parts as in FIG. 10 will be omitted, and only different parts will be described in detail.
[0121]
In this case, as shown in FIG. 11A, two vertical synchronizing signals VD having a regular pulse width and two vertical synchronizing signals VD 'having a short pulse width are generated in each frame, thereby shortening the period of the entire frame. .
[0122]
Also in this case, when a trigger is given and the first charge transfer pulse TGB is issued, the charges in the photodiodes 201a and 201b are transferred to the substrate side by the first pulse of the charge discharge pulse VSUB synchronized with the charge transfer pulse TGA. After discharging, the exposure time A is from the last one pulse to the charge transfer pulse TGA, an image signal is output at the timing of the charge transfer pulse TGA, and a charge discharge pulse synchronized with the charge transfer pulse TGA is also provided. The charge in the photodiodes 201a and 201b is discharged to the substrate side by the first pulse of the VSUB, and the exposure time B is set from the last pulse to the next charge transfer pulse TGB, and the timing of the charge transfer pulse TGB But it also outputs image signals.
[0123]
Also in this case, the transfer pulse VCCD shown in FIG. 9D is continuously driven at a high speed from an appropriate time before the start of exposure in which no pixel shift (image shift) is performed. This operation is continued until the charge transfer pulse TGA shown in FIG. 3C or the charge transfer pulse TGB shown in FIG. Then, the exposure is completed, and the image signal (image signal) SIG is read.
[0124]
Accordingly, in this case, since the period of one frame is shortened, the imaging time can be shortened, and the same effect as in the fifth embodiment can be expected.
[0125]
In addition, the present invention is not limited to the above-described embodiment, and can be variously modified in an implementation stage without departing from the spirit of the invention.
[0126]
Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent features. For example, even if some components are deleted from all the components shown in the embodiments, the problem described in the column of the problem to be solved by the invention can be solved, and the problem described in the column of the effect of the invention can be solved. In the case where the effect described above is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.
[0127]
The embodiments described above include the following inventions.
[0128]
(1) The image sensor has a driving means for outputting one line of interlaced output every m lines, and sets the driving speed of the charges transferred in the vertical transfer path to the normal speed just before the transfer of the charges m times before the displacement driving. An electronic imaging apparatus, which performs the operation at a higher speed and discharges unnecessary charges.
[0129]
In this way, even with an interlaced image sensor, it is possible to capture a high-quality image with reduced background unevenness noise generated by smear.
[0130]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electronic imaging apparatus and method used for a microscope capable of acquiring a high-quality captured image without unevenness of the substrate.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a microscope system to which a first embodiment of the present invention is applied.
FIG. 2 is a diagram illustrating a schematic configuration of an electronic imaging apparatus to which the first embodiment is applied;
FIG. 3 is a diagram showing a timing chart for explaining the operation of the first embodiment.
FIG. 4 is a timing chart for explaining an operation of a modification of the first embodiment.
FIG. 5 is a diagram showing a timing chart for explaining the operation of the second embodiment of the present invention.
FIG. 6 is a diagram for explaining pixel shifting applied to a third embodiment of the present invention.
FIG. 7 is a timing chart illustrating the operation of the third embodiment.
FIG. 8 is a diagram showing a timing chart for explaining the operation of the fourth embodiment of the present invention.
FIG. 9 is a view for explaining an element structure of a CCD for interlaced reading used in a fifth embodiment of the present invention.
FIG. 10 is a diagram showing a timing chart for explaining the operation of the fifth embodiment.
FIG. 11 is a diagram showing a timing chart for explaining the operation of the sixth embodiment of the present invention.
FIG. 12 is a diagram for explaining an element structure of a general imaging element (CCD).
FIG. 13 is a diagram showing a timing chart for explaining the operation of a general imaging device (CCD).
FIG. 14 is a timing chart illustrating another operation of a general imaging device (CCD).
[Explanation of symbols]
1. The microscope body
2. Stage
3 ... Sample
4: Objective lens
5. Trinocular tube unit
6. Eyepiece unit
7 ... Imaging lens unit
8. Electronic imaging device
11 ... CCD
12. Photographic optical system
13 ... Shading filter
14 ... TG
15 ... SG
16 CDS circuit
17… AMP
18 ... A / D converter
19 ... Image memory
20 ... Memory controller
21 ... Image signal processing circuit
22 LCD
23 ... DRAM
24 ... compression / expansion circuit
25 ... CPU
26 Recording medium
27 ... Operation unit
31 ... Piezo driver
201 ... photodiode
201a. 201b Photodiode
202: Vertical CCD
203 horizontal CCD
204 ... Amplifier

Claims (5)

In an electronic imaging device that captures an observation image of a microscope,
Two-dimensionally arranged photoelectric conversion elements that generate electric charges according to the amount of light of the observation image, a vertical transfer path that transfers electric charges of the photoelectric conversion elements in a vertical direction, and transfer via the vertical transfer path An image sensor having a horizontal transfer path for transferring the electric charges in a horizontal direction,
Immediately before transferring the charge of the photoelectric conversion element as an image signal to the vertical transfer path, the driving speed of the charge to be transferred in the vertical transfer path is higher than a normal speed, and an unnecessary charge discharging operation is performed. Electronic imaging device. 2. The imaging device according to claim 1, wherein an exposure time for controlling an amount of light incident on the photoelectric conversion unit is settable, and the presence or absence of the unnecessary charge discharging operation is determined according to the exposure time. 3. Electronic imaging device. Displacement means for displacing the relative position of the observation image and an image sensor that captures the observation image,
2. The image processing apparatus according to claim 1, further comprising: a reading unit that reads out from the imaging device image signals acquired corresponding to the relative positions of the observation image and the imaging device displaced by the displacement unit. Electronic imaging device. 4. The electronic image pickup apparatus according to claim 3, wherein the unnecessary charge is discharged from an image signal read from the image pickup device by the reading unit. The two-dimensionally arranged photoelectric conversion elements that generate electric charges according to the amount of light of the observation image, a vertical transfer path that transfers electric charges of the photoelectric conversion elements in a vertical direction, and the electric charges transferred through the vertical transfer paths An electronic imaging method for capturing an observation image of a microscope having an imaging device including a horizontal transfer path that transfers the charge in a horizontal direction,
Immediately before transferring the charge of the photoelectric conversion element as an image signal to the vertical transfer path, the driving speed of the charge to be transferred in the vertical transfer path is higher than a normal speed, and an unnecessary charge discharging operation is performed. Electronic imaging method.

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