JPH02280585A - Image pickup device - Google Patents

Abstract

PURPOSE:To expand the dynamic range of an image pickup element by dividing a video signal by one pattern for exposure period of one pickup into two, reading the signal separately for the first and latter halves, applying base clip to the signal of the absolute value of the difference, adding the result and using it as a signal correction and outputting after subtraction correction. CONSTITUTION:A system controller 13 outputs a readout pulse respectively at the point of time when a time being a half the exposure time elapses and at the end of the exposure time. A difference extraction circuit 14a receives a data (a) being a 2nd readout output video signal and a data (b) being a 1st readout output video signal to obtain the difference of the both and to obtain its absolute value. Thus, a picture data corresponding to a blur is obtained and the result is given to a clip level processing section 14 to eliminate the portion of the signal below a prescribed value. Then the data L1 clipped by the clip level processing section 14 is given to an adder circuit 14c as a negative data and the data is added to an output from an adder circuit 10. Thus, deviation signals are almost eliminated to prevent blur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to, for example, a still video camera system, and more particularly to an imaging device in which the dynamic range of a solid-state imaging device is expanded. [Prior Art] In recent years, still video cameras (electronic still cameras) that use still video disks having the same structure as floppy disks as recording media have appeared. In this camera, for example, the image reproduction processor is configured to be electrically and mechanically removable, and images captured by the camera alone can be recorded on a still video disc built into the camera, and the camera can also be used for image reproduction. The system is connected to a processor for playing back images recorded on a still video disk, and the images can be viewed on display or as a hard copy. By the way, in such a still video camera,
An imaging device such as a CCD (solid-state imaging device) is used as an imaging device for capturing images. As shown in FIG. 9, such an image sensor has a predetermined saturation level LS, and in a still video camera, light accumulation reaches a maximum LS within the horizontal scanning period LH of the television. , this LS becomes the saturation level. Therefore, the output is saturated when the light 11Ls exceeding the saturation level LS is incident within this period il1. In such a case, a conventional method for expanding the dynamic range is to read out the charges accumulated in the image sensor twice and add them together to obtain a video signal for one image. However, in this method, the shutter speed is doubled, one screen is photographed twice, that is, photographed twice in succession, and the video outputs of each photograph are added and synthesized to obtain the image. That is, as shown in FIG. 1O, 111
Adding the first readout output video signal captured by the second shutter operation and the second readout output video signal captured by the second shutter operation, and setting the shooting time for each shutter operation to half the normal exposure time; The effect of the saturation level LS is removed by making the amount of incident light during each photographing time not exceed the saturation level LS so that the video signal after addition is at the original level. [Problem 8 to be solved by the invention] As described above, the image sensor has a saturation level with respect to the amount of incident light, and the image sensor becomes saturated with the amount of light exceeding this saturation level, resulting in poor resolution. Therefore, in order to eliminate the influence of this saturation, there is a conventional method in which one image is photographed twice by two shutter operations to obtain respective video signals, and the two are added to obtain one image. However, in a still video camera, a series of sequences are performed in synchronization with a television synchronization signal so that the captured images can be played back and viewed as television images. In the case of the NTSC system, the vertical synchronization is 1/60 seconds in the case of the field sequential system, and therefore,
The readout time is also limited to a maximum of once per field. In this case, if the above-mentioned dynamic range expansion method is adopted, one image is obtained by performing two shootings, so the second shooting will be delayed by 1/80 seconds from the first shooting. This delay is not a problem when photographing stationary objects or slow-moving subjects, but it causes a huge problem when photographing fast-moving subjects. For example, if the shutter speed is 11500 or l/1000
As you can easily understand by assuming a case where the image will be blurred if you do not adjust it to a fast speed, even if you release the shutter twice with an exposure time that is half the shutter speed above, there will be a time difference of 1780 seconds between the two. Misalignment is unavoidable, and therefore the first and second images will have a large misalignment. Then, when these two images are added together, the difference between the two images results in a highly blurred image, and in the end, if you try to photograph a moving subject, you will not be able to take a clear photograph. Therefore, the purpose of this invention is to expand the dynamic range of the image sensor and to obtain a still image that can capture clear images even of fast-moving subjects.
The object of the present invention is to provide an optimal imaging device for use in video cameras and the like. [Means for Solving the Problems] In order to achieve the above object, the present invention has taken the following measures. That is, in a device that reads out the output signals of the same pixel in an image sensor at least twice and adds them to obtain a video signal for one screen, firstly, the video signal for one screen has the exposure period of one shooting. Means for dividing into two and controlling readout for the front and rear halves separately, taking the difference between these read signals, base-clipping the signal of the absolute value of the difference and using it as a correction amount for the above-mentioned added signal, and performing subtraction correction. and a correction means for outputting the output. Second, the correction means is configured to be read out by the readout control means. Furthermore, thirdly, the correction means selects whether or not to add the two read signals according to the incident light amount information or the focal length information of the photographic lens, and performs the addition correction. [Effects] By taking such measures, the following effects will be exhibited. That is, the dynamic range of the image sensor is expanded by reading the output signals of the same pixel in the image sensor at least twice and adding them to obtain a video signal for one screen. The control means controls the video signals for the xiii planes by dividing the exposure period of one shooting into
It is divided and read out separately for the first and second half to obtain two video signals. Then, in order to remove the blurring after addition and synthesis when there is a shift between the two images, correction is applied by the correction means, but in the case of the first invention, this correction Then, the signal of the absolute value of the difference is base-clipped and used as the correction amount of the added signal, and the subtractive correction is output.・Thus, the portion corresponding to the shift will be removed by calculation correction, and only the portion without the shift will be combined. Therefore, the dynamic range of the image sensor can be expanded, and the occurrence of blur due to image shift can also be suppressed. Further, in the case of the second invention, the correction means detects the movement of the subject from the two signals read out from the readout control means, and when the movement is less than a certain value, adds the read signals. Then, when the motion is above a certain value, one of the video signals obtained by reading out twice without addition processing is output with twice the word width. As a result, in the case of the second invention, when the motion is below a certain value, it is added and synthesized as is, and when the movement is above a certain value, one of the video signals is amplified twice without performing addition processing. The dynamic range of the image sensor can be expanded by a simple correction operation such as outputting, and furthermore, it is possible to suppress the occurrence of blur due to image shift. Further, in the case of the third invention, the correction means selects whether or not to add the two read signals according to the incident light amount information or the focal length information of the photographing lens, and performs the addition correction. In other words, when the exposure time or focal length is long, there is a high possibility that the two video signals will be out of alignment, so in this case, one of the video signals obtained by reading out twice is read out twice without performing additive correction. It is amplified twice and output, and in other cases the two video signals are added together. Thereby, the dynamic range of the image sensor can be expanded with only a simple operation, and the occurrence of blur due to image shift can also be suppressed. Therefore, according to the present invention, it is possible to expand the dynamic range of an image sensor and obtain a clear image even of a fast-moving subject, thereby providing an optimal imaging device for use in still video cameras, etc. I can do it. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Here, to touch on the technology that is the premise of this device, which will be explained below, the target is a still video camera.
The image signal from the image sensor is modulated, amplified, and applied to a magnetic recording medium for magnetic recording. In order to be able to read out the image sensor and play it back as a TV image,
l/ which is the time of one field in the case of field sequential
This is synchronized with the vertical synchronization signal VD every 60 seconds. Since a still video disk is used as the magnetic recording medium, the same applies to the drive system of the magnetic recording medium. In a magnetic recording medium, image information is concentrically recorded on the magnetic surface of a magnetic disk based on a flexible thin circular plastic film by a recording/reproducing magnetic head that moves radially using a head access mechanism. When recording image information in a still video camera, for example, up to 50 concentric recording tracks are formed at equal intervals, and each track stores one frame of field images. recorded. And 1
Since a field image is recorded for one frame per track, the drive system of the magnetic recording medium rotates the magnetic recording medium once in 1780 seconds, generates a pulse for each rotation, and generates a pulse that corresponds to the vertical synchronization signal VD. Used as a synchronization pulse. The camera's trigger button, which is the shutter button, is a two-stage switch. When you press the trigger button, the first
The second stage is activated, causing the photometry system to function and the drive for the magnetic recording medium to rotate.The photometry system and AP (autofocus) system measure the exposure and distance of the subject, and based on these measurement results, the system controller After determining the exposure and shutter speed, and controlling the exposure and shutter speed settings and autofocus settings, in the second stage, the shutter is driven in synchronization with the synchronization pulse, exposure is performed, and an image is taken. After reading the video signal from the element and changing 31,
This modulation signal is sent to the drive of the magnetic recording medium, applied to the magnetic head, and recorded on the recording track. For reproduction, a magnetic head reads the recorded signal from the recording track, demodulates it, performs certain processes such as dropout compensation and skinny distortion correction, adds a synchronization signal, and outputs it to a TV monitor, etc. You can display it as an image, or print it out as a hard copy using a video printer. The apparatus of the present invention is such a still video camera system in which the imaging/recording system is constructed as shown in FIG. That is, l is the camera lens, 2 is the aperture, 3 is the shutter, 4 is the half mirror, 15 is the solid-state image sensor, 6 is the A/D converter, 7 is the changeover switch, 8 is the drive control signal generator, and 9 is the field. 11 is a mirror for reflection, 12 is a photometry section, 13 is a system controller, and 14 is a signal correction section. Lens 1, diaphragm 2, shutter 3, half mirror 4, and mirror 11 constitute an optical system, and the optical image of the subject passes through lens 1, is distributed by half mirror 4, and is sent to solid-state image sensor 5 and mirror 11. be guided. The distributed light incident on the mirror 11 is guided to the photometry section 12. The photometer 1112 detects the amount of exposure light from the distributed light and measures the distance of the subject image, and the system controller 13 receives this distance measurement data and data on the amount of exposure light, and if the shutter speed is set to manual, the data on the amount of exposure light. The aperture value is determined based on the aperture value, and if the aperture value is set manually, the shutter speed is determined based on the exposure light amount data, and the aperture value setting signal is given to the aperture drive mechanism to set it. Focus control is performed by giving a control signal to the drive mechanism of the lens l based on distance measurement data so that the subject image is focused on the light receiving surface of the solid-state image sensor 5. Note that the shutter speed corresponds to the set time by stopping the drive command when the elapsed time after giving the shutter drive command reaches the time corresponding to the shutter speed setting time. The system controller 13 is in charge of the control center of the entire camera, and the solid-state image sensor 5 uses, for example, COD, and when half of the exposure time determined by the shutter speed has elapsed and the exposure Control is performed to read out the stored electric current at the end of each time period. This readout control is performed by the drive control signal generator (SSG; sync signal generator) Jl that generates a synchronization signal for reading drive of the CCD, and the drive control signal generator 8 is controlled by the system controller 13.
This is done by That is, the system controller 13
After starting the shutter drive, outputs a readout pulse at the time when half of the exposure time determined by the shutter speed has passed and at the end of the exposure time, and upon receiving this readout pulse, the drive control signal generator 8 starts the COD readout drive. Generates synchronization pulses for Further, the drive control signal generating section 8 executes a process for controlling unnecessary charge release of COD according to a command from the system controller 13 at the time when the trigger button is operated, and also executes an electronic shutter release drive control. For a period of up to 2 fields from CO
It is assumed that control is performed so that D is placed in a state where it can be exposed. 'It also has a mechanical shutter, which is controlled to open after the trigger button is operated until the open time of the electronic shutter reaches the exposure time. The A/D converter 0 converts the readout video signal of the solid-state image sensor 5 into a digital signal, and the changeover switch 7 converts the readout video signal to one of the adder circuit 10 and the field memory 9. This is for switching routes. The field memory 9 is a memory having a capacity for one field, and is used to store the first readout output video signal among the image signals read out twice from the solid-state image sensor 5 for each shooting. Therefore, the changeover switch 7
gives the first read output video signal to the field memory 9;
The second readout output video signal is switched to be supplied to the adder circuit 10, and at the output timing of the second readout output video signal, the first readout output video signal is sent from the field memory 9 in synchronization with the second readout output video signal. Read out and add the circuit! The system controller 13 is configured to control the amount to give $0. The first readout of the video signal from the solid-state image sensor 5 is based on a readout pulse that is output when half of the exposure time has elapsed. The accumulated charges are transferred, and the second readout of the video signal is performed after the exposure time ends. In other words, in COD, as shown in Fig. 3, charges corresponding to the amount of incident light are accumulated in the cells CL, which are pixels structured like the eyes of the substrate, and when readout control is performed, charges are accumulated for each group of cells CL in the same column. The configuration is such that charges are transferred to a vertical transfer path VT provided for the vertical transfer path VT, and the charges in this vertical transfer path VT are outputted to the outside by output control. In order to synchronize the external output of the charges of the vertical transfer path VT with the television system, the first vertical synchronization pulse after the transfer to the vertical transfer path VT is generated, and one vertical period (one field) starts from this point. period), and the charge is transferred from COD to the vertical transfer path VT for the second time at the vertical synchronization pulse generation timing at the end of the one vertical period. Transfer path VT
The system controller 13 is configured to perform control such as outputting the electric charge to the outside. In addition, in this system, the first video signal is read from the solid-state image sensor 5 when half of the exposure time has elapsed, but since there is still half of the exposure time left after that, charge is accumulated during that time. continues, thus making it possible to read out the charge a second time. The signal correction unit 14 is a processing circuit for correcting the deviation in the case of a moving image with respect to the signal output from the addition circuit IO, and sends the video signal whose deviation has been corrected to the subsequent process processing unit, Perform necessary processing as a video signal. Then, after modulation, it is recorded on a recording medium. Next, the operation of this apparatus having the above structure will be explained with reference to FIG. When you press the camera's trigger button, trigger button operation 1
The mechanical shutter opens at the second step, and the optical image of the subject is captured by lens 1.
The light is distributed by the half mirror 4 and guided to the solid-state image sensor 5 and the mirror 11. The distributed light incident on the mirror 11 is guided to the photometry section 12. The photometer I2 detects the amount of exposure light from the distributed light and measures the distance of the subject image, and the system controller 13 receives this distance measurement data and the data of the amount of exposure light, and if the shutter speed is set to manual, the data of the amount of exposure light. The aperture value is determined based on 1, and if the aperture value is set manually, the shutter speed is determined based on the exposure light amount data, and the aperture value setting signal is given to the aperture drive mechanism to set it. Also, based on the distance measurement data, the solid-state imaging probe 5
By giving a drive command to close the mechanical shutter when the elapsed time after giving a lens command so that the subject image is focused on the light receiving surface of the lens reaches the time corresponding to the shutter speed setting time, the shutter speed corresponding to the setting time is get (
Figure 2 (b), (c)). On the other hand, the solid-state image sensor 5 uses, for example, a COD, and is controlled to read out #& accumulated charges at the time when half of the exposure time determined by the shutter speed has elapsed and at the end of the exposure time, respectively. Ru. This readout control is performed by the drive control signal generation section 8 which generates a synchronization signal for the readout drive of the COD, and the drive control signal generation section 8 is controlled by the system controller 13. That is, after starting shutter driving, the system controller 13 outputs readout pulses at the time when half of the exposure time determined by the shutter speed has elapsed and at the end of the exposure time, respectively (see FIG. 2).
d)) Upon receiving this readout pulse, the drive control signal generator 8° generates a synchronizing signal for readout driving of the CCD. Further, the drive 1t control signal generating section 8 executes a process of controlling unnecessary charge release of COD according to a command from the system controller 13 when the trigger button is operated, and also executes shutter release drive control. After that, the COD is controlled to be in an exposed state for a maximum of two fields. The readout video signal of the solid-state image sensor 5 is the front;
It is converted into a digital signal by the /D converter B, and this digital readout video signal is sent to the adder circuit lO and the field memory 9 by the changeover switch 7.
give to one of them. The field memory 9 is a memory having a capacity for one field, and stores the first readout output video signal among the image signals read out twice from the solid-state image sensor 5 for each photographing. Therefore, the changeover switch 7 is controlled by the system controller 13 to apply the first readout output video signal to the field memory 9 and the second readout output video signal to the adder circuit IO, and also provides the second readout output video signal to the adder circuit lO. At the output timing of the output video signal, the first readout output video signal is read out from the field memory 9 in synchronization with the second readout output video signal, and the adder circuit 10 reads out the first readout output video signal from the field memory 9.
It is controlled to give As shown in FIG. 2(d), the first
The readout of the video signal for the second time is based on the readout pulse that is output when half of the exposure time has elapsed, and this readout pulse causes the COD solid-state image sensor 5 to transfer the current accumulated charge to the vertical transfer path, and The second reading of the video signal is performed after the exposure time ends. That is, COD
As shown in Fig. 3, a charge corresponding to the amount of incident light is accumulated in the cell CL, which is a pixel configured like an eye on the base, and
When read control is performed, charges are transferred to the vertical transfer path VT provided for each group of cells CL in the same column, and by output control, the charges in this vertical transfer path VT are output to the outside. . Then, in order to synchronize the output of the charges on the vertical transfer path VT to the outside with the television system, the first vertical synchronization pulse after the transfer to the vertical transfer path VT is generated at the point in time as shown in FIG. 2(e). 1 vertical period from this point (1
field period), the charge is transferred from the CCD to the vertical transfer path VT for the second time at the vertical synchronization pulse generation timing at the time when the one vertical period has elapsed, and then from this point on, for one vertical period, The system controller 1 controls the output of the charge in the vertical transfer path VT to the outside.
3 will be implemented. In addition, in this system, the first video signal is read from the solid-state image sensor 5 when half of the exposure time has elapsed, but since there is still half of the exposure time left after that, charge is accumulated during that time. continues, thus making it possible to read out the charge a second time. Although omitted in FIG. 1, the signal sent from the switch 7 to the adder circuit 10 and the read signal from the field memory 9 are given to the signal correction section 14.
4 examines whether or not the two signals are moving images based on the deviation between the two signals, and in the case of a moving image, corrects the signal output from the adder circuit 10 to remove the deviation. Then, the video signal that has passed through the signal correction section 14 is sent to the subsequent process processing section, and the necessary information as the video signal is
After being processed and modulated, it is recorded on a recording medium. Here, an example of the configuration of the signal correction section 14 is shown in FIG. 4. As shown in the figure, the signal correction unit 14 includes a difference extraction circuit 14a that obtains absolute value data of the difference between the video signal data a sent from the changeover switch 7 to the adder circuit IO and the video signal data b read from the field memory 9; A clip level processing section 14b1 cuts a portion of the absolute value of the difference between the video signal data a and b outputted by the difference extraction circuit 14a that is less than or equal to a predetermined value; This circuit is composed of an adder circuit 14c that performs subtraction from the output of . The operation of such a circuit will be explained with reference to FIG.
The difference extraction circuit 14a extracts data a (fifth
(a)) and data b of the first readout output video signal which is the readout output from the field memory 9 (FIG. 5(b))
Then, the difference between the two (Fig. 5(d)) is obtained, and then its absolute value data is obtained (°Fig. 5(0)). In the case of a moving subject, both data a. There is a difference in b, and if you simply add and synthesize the two, Figure 5 (e)
As shown in the figure, a difference in level occurs by the amount S that the image has moved, and this appears as a blur in the image. Therefore,
In order to remove this blur, the difference between both data a and b (Fig. 5 (d)) is obtained as described above, and then the absolute value data is obtained (Fig. 5 (e)). By obtaining image data of and passing it through the clip level processing section 14b, parts below a predetermined value are cut. This is data a
, b are originally images with temporal shifts, and it is unavoidable that there will be differences in brightness levels even in the same pixel area, so if you remove all even the slightest level differences, the image will be distorted because it is digital processing. This is because there is a concern that the image may become unnatural, so this is avoided by setting the clip level LV (-L2), which is a predetermined threshold level, as a dead zone and cutting the part below this level. . Then, the data clipped by the clip level processing unit 14 is given to the addition circuit 14c with Ll as negative data, and the output from the addition circuit IO (addition value of data a and b) (FIG. 5(C)) Correct by adding . If there is a movement between data a and b, simply adding them together will reveal the deviated part, but by adding the above correction, this deviation will almost be deleted (see Figure 5 (r ))
, blurring can be prevented. Of course, for the deviation data that is equal to or greater than the clip level, deviation data at a level less than the clip level remains, but this is small and does not pose a problem. FIG. 6 shows another embodiment of the signal correction section 14. In this example, movement of the subject data is detected by comparing the first and second readout output video signals a and b in correspondence with cells, that is, pixels of the image sensor, and only when there is no movement, both video signal data a and , b are added, and when there is movement, a correction is made so that the brightness change in the area of the shifted part is smoothed, and then the summation is performed. In this case, the adder circuit lO used in the previous embodiments is unnecessary, and the signal correction section 14 uses the video signal "data a" sent from the changeover switch 7 and the read video from the field memory 9 synchronized with the data a. a motion detection unit 141 which receives signal data b pixel-wise and detects the presence or absence of a difference between the two data values, and outputs a coefficient value K to perform correction when motion a is detected; First and second correction circuits 142 and 143 that receive the output coefficient value of the motion detection unit 141 and correct the coefficient value by a factor of 2, and among these correction circuits 142 and 143, 142 and the second readout output video signal data a obtained through the correction circuit 1
43 and the first readout output video signal data b obtained through the first readout output video signal data b. Such a circuit receives data a of the second output video signal input from the changeover switch 7 and data b of the first output video signal read out from the field memory 9 in pixel correspondence. The motion/detection unit 141 detects the difference between the two, and if there is a difference, determines that there is movement. When the motion detection section 141 determines that there is motion, it generates a coefficient value for correction, and the correction circuit 142.1 generates a coefficient value for correction.
Give to 43. For example, as shown in FIG. 7, if the brightness of pixels PI-PG is changing, there is no change in brightness in pixels P1-P3, so the coefficient value K is set to ``1'', and therefore 2- is also "1", and it is determined that there is a pixel change for the first time at the position of pixel P4, but since it is not possible to respond in terms of speed, the coefficient value is still set to "1" at this point. Then, at the time of pixel P5, it is determined that there is a pixel change from P4, and in this case, there is a continuous change, so for the first time, the coefficient value K is set to rl/
Change only 2J. Therefore, in the example shown, the coefficient value is r
l (1/2) J, and the coefficient value 2- is rl/2J
becomes. Furthermore, since it is determined that there is a change even at P5,
At the time of P6, both K and 2- are further changed by "l12", and the coefficient value K is set to "2" and the coefficient value 2-K is set to "0". This multiplier is used as a multiplier to multiply the input data a and b at each time by this multiplier, and the result is added in an adder circuit 144 and output. The coefficient value is not limited to the above example, but the point is that pixels are compared and if there is a change, the data is processed to be corrected so that the brightness changes smoothly. In the above example, the brightness of data a becomes high, but if the brightness of data a becomes equal to data b, from that point onwards, the coefficient value K is changed from "2" to rl (
1/2) J, change it to "1", and change the coefficient value 2- to "0".
” to rl12J to “1”. This results in
The brightness of the shifted portion changes smoothly. By the way, if the exposure time or the focal length of the lens is long, there is a high possibility that the two video signals will be out of sync. An example of how to deal with this case will be described below. Since the system controller 13 performs autofocus and exposure control of the camera, the system controller 13 controls the changeover switch 7 shown in FIG. 8 according to the exposure time or focal length. The changeover switch 7 is configured to select one of the three directions, and an amplifier 15 with an amplification factor of 6 dB is provided as the signal correction section 14. When the exposure time or focal length is short, the first readout output video signal is stored in the field memory 9, and when the second readout output video signal is output, this and the first readout output video signal are stored in the field memory 9. are applied to an adder circuit 10, added and synthesized, and output. On the other hand, if the exposure time or focal length is long, there is a high possibility that the two video signals will be out of alignment. The signal is amplified by 6dtl and output. In this system, the image sensor divides the period into two during the same shirt opening/closing period, reads the signals twice before and after, and adds and synthesizes the signals.The resulting signal is doubled after synthesis, so the amplifier 15 needs to amplify the input by two times. Therefore, the amplification factor is 8 dB. In this way, when the exposure time or focal length is long, there is a high possibility that the two video signals will be out of alignment. is amplified twice and output,
Otherwise, by adding two video signals, it is possible to expand the dynamic range of the image sensor with only a simple operation, and it is also possible to suppress the occurrence of blur due to image shift. In this way, this system reads the output signals of the same pixel in the image sensor at least twice and adds them to obtain a video signal for one screen. means for dividing the exposure period into two and controlling readout separately for the first and second halves, taking the difference between these read signals, base-clipping the signal of the absolute value of the difference and using it as a correction amount for the added signal, or a correction means detects the movement of the subject from the two signals read out by the readout control means, and when the movement is less than a certain value, the correction means reads out the signal. or the correcting means is configured to perform addition processing on the two signals read out, and when the value exceeds a certain value, one of the two signals read out by the readout control means is doubled and outputted; Select whether or not to add the two signals according to the incident light amount information or the focal length information of the photographing lens, and if the exposure time or focal length is long, there is a possibility that the two video signals will be out of alignment. In this case, one of the video signals obtained by reading twice is amplified twice and output without performing addition correction, and in other cases, the two video signals are added and output. It is something to do. In such a configuration, the dynamic range of the image sensor is expanded by reading the output signals of the same pixel in the image sensor at least twice and adding them to obtain a video signal for one screen. Then, the readout control means divides the exposure period of one shooting into two and reads out the first and second halves of the video signal for one screen separately, and obtains the two video signals in the form of two video signals. In order to remove blur after additive synthesis if there is,
Correction is applied by the correction means, and in the case of the first invention, this correction is performed by taking the difference between these read signals, base-clipping the signal of the absolute value of the difference, making it the correction amount for the added signal, and subtracting it. By correcting and outputting, the portion corresponding to the deviation is removed by subtraction correction, and only the portion without deviation is synthesized. Therefore, the dynamic range of the imaging probe can be expanded, and furthermore, This also makes it possible to suppress the occurrence of blur due to image shift. Further, in the case of the second embodiment, the correction means detects the movement of the subject from the two signals read out from the readout control means, and when the movement is less than a certain value, adds the readout No. 6. , when the motion is above a certain value, the video signals are read out twice without addition processing, and each of the video signals is obtained separately.
One of the signals is amplified twice and output, so that when the movement of the subject image is below a certain value, it is added and synthesized as is, and when the movement is above a certain value, the video signal is added without addition processing. The dynamic range of the image sensor can be expanded by a simple operation of amplifying one of the two signals twice and outputting the same, and furthermore, it is possible to suppress the occurrence of blur due to image shift. Further, in the case of the third embodiment, the correction means selects whether or not to add the two read signals according to the incident light amount information or the focal length information of the photographing lens and performs addition correction. In other words, when the exposure time or focal length is long, there is a high possibility that the two video signals will be out of alignment, so in this case, one of the video signals obtained by reading out twice without performing additive correction. It amplifies the image twice and outputs it, and otherwise adds the two video signals.This allows the dynamic range of the image sensor to be expanded with simple operations, and it also eliminates the problem of image shift. This also makes it possible to suppress the occurrence of blur. Therefore, according to this device, it is possible to expand the dynamic range of the image sensor and to obtain a clear image even of a fast-moving subject, so that it can be applied to a still video camera, etc. to provide an optimal image pickup device. I can do it. It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof. For example, in the embodiments described above, a still video disc is used as the recording medium. Although we used a method for recording video signals, other storage media such as memory cards can also be used. [Effects of the Invention] As detailed above, according to the present invention, it is possible to expand the dynamic range of an image sensor, and also to obtain a clear and blur-free image even of a fast-moving subject.
A noise reduction effect can also be obtained by adding two signals at the same time, and the present invention can be applied to still and video cameras to provide an optimal imaging device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 712 is a timing chart for explaining its operation, and FIG.
4 is a block diagram showing another embodiment of the present invention, FIG. 5 is a timing chart for explaining its operation, and FIG. 6 is a further embodiment of the present invention. A block diagram showing an example, FIG. 7 is a diagram for explaining its operation, FIG. 8 is a block diagram showing another embodiment of the present invention, and FIGS. 9 and 10 are a dynamic range and its expansion method. FIG. l... Camera lens, 2... Aperture, 3... Shutter, 4... Half mirror 15... Solid-state image sensor,
6...^/D. Converter, 7... Changeover switch, 8... Drive control signal generation section, 9... Field memory, IO... Addition circuit, 11... Mirror for reflection, 12... Photometry section, 13... System controller, 14... Signal correction unit. Applicant's agent Patent attorney Jundai Tsuboi Illustration

Claims (3)

[Claims] (1) In a device that reads the output signals of the same pixel in an image sensor at least twice and adds them to obtain a video signal for one screen, the video signal for one screen is obtained by dividing the exposure period of one shooting into two. means for controlling the reading of the front and rear parts separately, and a correction means for calculating the difference between these read signals, base-clipping the signal of the absolute value of the difference, making it the correction amount of the added signal, subtracting it, and outputting it. An imaging device comprising: means. (2) In a device that reads the output signals of the same pixel in an image sensor at least twice and adds them to obtain a video signal for one screen, the video signal for one screen is obtained by dividing the exposure period of one shooting into two. means for controlling the reading of the front and rear parts separately, and a correction means for detecting the movement of the subject from these two read signals and adding the read signals when the movement is less than a certain value. An imaging device characterized by: (3) In a device that reads the output signals of the same pixel in an image sensor at least twice and adds them to obtain a video signal for one screen, the video signal for one screen is obtained by dividing the exposure period of one shooting into two. means for separately controlling readout of the front and rear halves, and correction means for selecting whether or not to add the two read signals according to incident light amount information or focal length information of a photographing lens and performing addition correction. An imaging device characterized by: