JP2001298667A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-image continuous photographing method which can obtain the record images of high picture quality that never lower the saturation level while satisfying the condition to obtain two images with no shift of timing caused between them. SOLUTION: The setting change of VSUB is started after the shading is started by a mechanical shutter 104 and the value of VSUB is switched from VN to VL that is lower than VN before the shading is completed. Thereby the control is carried out to set a higher overflow level OFL of the electric charge accumulation part of a CCD image pickup device 105 in a period covering a point of time when the full exposure is over and a charge transfer pulse TG2 is outputted compared with a period of the main exposure 1. Thus, the saturation level of a 2nd image can be relatively set higher than a 1st image and accordingly it is possible at least to set the same saturation level between both images and to continuously photograph two images with even high picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly, to an image pickup apparatus for picking up a subject image using an image pickup device such as a CCD.

[0002]

2. Description of the Related Art In recent years, various attempts have been made to obtain a captured image with a wide dynamic range by combining two images having different exposure amounts. In particular, in order to prevent a breakdown in processing that occurs when a subject moves during the capturing of two images, even when a destructive readout type imaging device such as a CCD is used, the two images obtained A reading method devised so as to minimize the timing deviation is described in, for example, Japanese Patent Application Laid-Open No. 4-207581.

[0003] The two-image continuous imaging technique in which the time difference is minimized is not limited to the wide dynamic range imaging described above.
It has the potential to be applied to various image quality enhancements and new imaging functions by image processing using images, and as such, technical expectations are high.

[0004]

In the use of synthesizing two images obtained by continuous imaging of two images, naturally, while satisfying a special restriction condition different from general imaging in that two images can be obtained without timing shift, it is natural. The image quality must not be degraded when capturing only one normal image. Further, even if a slight reduction in image quality is allowed,
Generally, it is required that the images have the same image quality, and when one of the images has a low image quality, a problem arises.

[0005] However, the above-mentioned special constraints impose limitations on methods capable of coping with various image quality deterioration factors as compared with the case of taking only one image. Had to be forced. From such a viewpoint, the present applicant has filed a patent application (Japanese Patent Application No. 2000-7).
No. 7136) proposes a technique capable of significantly reducing the occurrence of smear as compared with the conventional technique while satisfying the above-mentioned special constraint conditions.

However, even in such an imaging technique, particularly in the case of the second image, the saturation level of the image signal is lower than that of the normal image obtained by imaging only one image or the first image obtained by continuous imaging of two images. Is reduced. If this phenomenon is described in detail, it is caused by charge leakage in the photoelectric conversion accumulation region. Here, the above-mentioned charge leakage that is a problem of the present invention is, for example, remarkable after light shielding by a mechanical shutter, and a part of accumulated charge below an overflow level is lost with time in a charge accumulation portion of an image sensor. This is a phenomenon that the saturation level of the signal of the charge storage unit is reduced.

It is said that this is because the quantum mechanical fluctuation of electrons causes the electric charge to be discharged to the substrate side over the overflow level. At this time (unless new photocharges are generated), the leak current attenuates with the lapse of time after the light is shielded because the potential of the charge storage unit also decreases as the charge leaks. As a result, the accumulated charge amount, that is, the saturation signal amount of the output of the image pickup device shows a logarithmic function of attenuation characteristics with respect to the elapsed time after light shielding, and the saturation level becomes, for example, after 1-2 ms elapses. It drops to about 70%. Since this is a quantum mechanical effect, it can be neglected if the amount of charge to be handled is sufficiently large. However, the amount of charge per pixel has become extremely small due to the recent increase in the number of pixels in the imaging device, and this has become apparent. This is a rising phenomenon. By the way, the existence of this phenomenon is conventionally known. For example, in the interlaced scanning CCD image pickup device, a technique for taking measures against the problem that the accumulated charge amounts of the odd field and the even field do not match and a line step is generated is proposed. The present applicant has proposed the same (Japanese Patent Laid-Open No. 09-163239).

On the other hand, in the progressive scanning CCD image pickup device, such a problem does not occur in principle because the shutter is closed electronically by one charge transfer pulse (TG pulse). This is because the decrease in the saturation level due to the leakage occurs during a period until the charge is transferred from the charge storage unit to the vertical transfer path. Even when a mechanical shutter is used together with the mechanical shutter, the saturation level can be prevented from lowering by outputting the TG almost simultaneously with the closing of the shutter, and the TG is output long after the mechanical shutter is closed. This is because, even if the saturation level is reduced by performing the method, at least a line level difference as in the interlaced scanning type imaging device does not occur, and the image quality is only slightly deteriorated with respect to only one image.

However, with regard to the two-image continuous imaging technique, even when a progressive scanning CCD imaging device is used, the above-mentioned special restrictions are still imposed, so that it is generally not allowed to output TG almost simultaneously with closing the mechanical shutter. The problem due to the lowering of the saturation level becomes significant. Moreover, since this occurs only in the second image, there is a problem that the image quality of the first image and the second image is not uniform even if the deterioration is tolerable in general imaging. Will be invited.

[0010] Among the above-mentioned problems, in particular, for reference, an example of a problem caused by uneven image quality is a technique for detecting the movement of a subject by comparing the degree of correlation between two images. In this method, a reference window of a predetermined size is provided, for example, in the center of the first image, and has the same size as the reference window near the center of the second image, and the relative position coordinates from the reference window are (i, j). A plurality of detection windows are provided, and for each (i, j), the sum of the absolute values of the differences between the image signal of the reference window and the image signal of the detection window for each pixel is calculated. (I,
j) is obtained and this is used as a motion vector (x, y). This may be used for an auxiliary purpose such as, for example, compensating for a shift between the two images due to motion before synthesizing the two images, or canceling the synthesis if the shift is large. , May be used to detect motion information independently of synthesis. In such a correlation comparison, if the image quality of the two images to be compared is not uniform, it is apparent that a malfunction may occur.

Of course, before such a problem of uneven image quality, even if only one of the two images is used, deterioration of the image quality cannot be avoided under the constraint conditions of two-image shooting. In applications in which the image quality is improved by reducing the random noise by averaging the two images, the image quality of the second image is reduced, and the image quality of the total image is lower than the image quality that should be obtained. It is clear that it will.

The present invention has been made in view of the above circumstances, and while satisfying the constraint that two images can be obtained without a timing shift, firstly, the saturation level does not decrease, and secondly, the saturation level does not decrease. It is an object of the present invention to provide an imaging apparatus capable of realizing high-quality continuous imaging of two images in which the image quality of the two images is uniform by adjusting the degree of reduction in the saturation level between the two images even if this occurs.

[0013]

In order to solve the above-mentioned problems, the present invention provides a solid-state imaging device, driving means for driving the solid-state imaging device, and a transmission state of a subject image to an imaging surface of the solid-state imaging device. An optical shutter means capable of switching between a light-receiving state and a light-shielding state; and an imaging control means for controlling the driving means and the shutter means to control exposure and reading of an image signal. At the time of imaging of the target image, all exposure related to the imaging is started by switching from the light blocking state to the transmission state by the shutter means or outputting the final charge discharge pulse SUB by the driving means in the transmission state of the shutter means. Switching the transmission state of the shutter means to the light-shielding state to end all exposures relating to the imaging, and The driving means outputs a first charge transfer pulse TG1 during a period from the start of the full exposure to the end of the full exposure, thereby terminating the first exposure and simultaneously starting the second exposure. And starting the transfer path driving of the solid-state imaging device for reading the first image signal generated by the first exposure after the end of the entire exposure, and terminating the reading of the first image signal. Later, after the second image signal generated by the second exposure is transferred to the transfer path of the solid-state imaging device by the output of the second charge transfer pulse TG2,
It is configured to perform a transfer path drive for reading out the same, and controls the set value of the substrate bias voltage VSUB of the solid-state imaging device to a different value to correspond to the set value of the substrate bias voltage VSUB. The overflow level determined during the first exposure period before the output of the first charge transfer pulse TG1 is set to the first level from the end of the entire exposure to the output of the second charge transfer pulse TG2. By setting each of the periods to a second level higher than the first level,
The present invention is characterized in that the first image signal and the second image signal are configured to keep the same saturation level after readout.

In this imaging apparatus, control is performed such that the overflow level of the solid-state imaging device is set to be higher in the period from the end of the entire exposure to the output of the second charge transfer pulse TG2 than in the first exposure period. Is performed. As a result, the saturation level of the second image before the occurrence of the leak can be relatively increased with respect to the first image, so that at least the saturation levels of both the first and second images can be set equal, and the image quality of the two images is uniform. It is possible to realize high-quality continuous imaging of two images.

Further, the change of the set level of the overflow level from the first level to the second level is started and completed within a transition period from the transmission state to the light shielding state of the shutter means upon completion of all exposures. It is preferable to control so that

In the transition period in which the shutter means is closed, the illuminance on the plate surface of the solid-state image sensor gradually decreases, so that this period can be considered as a transition period from the bad influence of blooming to the bad influence of leak. On the other hand, raising the overflow level corresponds to switching from the blooming suppression state to the leak suppression state. Therefore, by starting and completing the change of the overflow level during the transition period in which the shutter means is closed, while suppressing the effect of blooming caused by increasing the overflow level, the problem due to the charge leak after the light incidence is cut off can be solved. It can be improved.

In particular, by using the control of gradually changing the overflow level from the first level to the second level in accordance with the transition of the shutter means from the transmissive state to the light-shielded state, the problem of blooming is reduced to the problem of leakage. In combination with the transition from the blooming suppression state to the leak suppression state, it is possible to obtain an optimal suppression effect according to the degree of occurrence of the problem.

Further, the exposure time is set equal between the first exposure and the second exposure, and a change in the subject is detected based on a difference between the first image signal and the second image signal. By providing the means for performing the above, it is possible to accurately detect the change of the subject from the two images having the same image quality.

Further, a means is provided for setting the exposure time equal for the first exposure and the second exposure, and for averaging and outputting the first image signal and the second image signal. , High S / N and high quality image signals can be obtained.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an imaging device according to an embodiment of the present invention. Here, a case where the present invention is implemented as a digital camera will be described as an example.

In the figure, reference numeral 101 denotes a lens system including various lenses; 102, a lens driving mechanism for driving the lens system 101; 103, an exposure control mechanism for controlling the aperture of the lens system 101; 104, a mechanical shutter; CCD color image pickup device with a built-in color filter, 106 a CCD driver for driving the image pickup device 105, 107 a pre-processing circuit including an A / D converter, etc., 108 a color signal generation process, a matrix conversion process, and other various types Digital processing circuit for performing digital processing of the digital camera, 109 is a card interface, 110 is a memory card, 11
Reference numeral 1 denotes an LCD image display system.

In the figure, reference numeral 112 denotes a system controller (CPU) for overall control of each unit; 113, an operation switch system including various operation buttons; 114, an operation for displaying an operation state and a mode state; Display system, 1
Reference numeral 15 denotes a lens driver for controlling the lens driving mechanism 102; 116, a strobe as a light emitting unit; 117, an exposure control driver for controlling the strobe 116;
Reference numeral 18 denotes a nonvolatile memory (EEPROM) for storing various setting information and the like.

In the digital camera of the present embodiment,
The system controller 112 performs overall control, and in particular, controls the mechanical shutter 104 and the driving of the CCD image sensor 105 by the CCD driver 106 to perform exposure (charge accumulation) and signal reading, and perform preprocessing. Digital processing circuit 10 via circuit 107
8, performs various signal processing, and records the data on the memory card 110 via the card interface 109.

The drive control of the CCD image sensor 105 is performed using various drive signals (charge transfer pulse TG, vertical drive pulse, horizontal drive pulse, substrate voltage VSUB, etc.) output from the CCD driver 106. CCD
The color image sensor 105 is composed of a charge storage section arranged in a matrix and charge transfer paths (vertical charge transfer path, horizontal charge transfer path) arranged horizontally and vertically, for example, progressive scan (sequential scan). A (scanning) type with a vertical overflow drain (VOFD) structure or the like is used.

When the charge transfer pulse TG is output, the transfer gate provided between each charge storage section and the vertical charge transfer path opens, and charges are transferred from each charge storage section to the corresponding vertical charge transfer path. You. The substantial exposure time is controlled by the output timing of the charge transfer pulse TG. Further, the substrate voltage VSUB is a substrate bias voltage for determining the maximum charge accumulation level (overflow level OFL) of the charge accumulation section, and this VSUB is the total charge on the substrate by superimposing a pulse of a large value here. Also used for forced discharge.

In the digital camera of the present embodiment,
Except for an imaging control sequence relating to continuous imaging of two images, which will be described in detail below, in particular, a portion relating to variable control of the overflow level OFL, operations and controls similar to those of a normal digital camera are performed. The description of the parts is omitted.

FIG. 2 shows a cross-sectional structure of an interline CCD having a vertical overflow drain structure, which is used as the image sensor 105 of the present embodiment. The n-type semiconductor substrate 400 has a first region 40 of a P well with a shallow junction.
1 and a second region 402 of a P well having a deep junction. The portion of the first region 401 where the junction n-type region is formed functions as a photodiode, that is, a so-called photoelectric conversion region (charge storage portion) 403.

A buried channel 404 is provided in the second region 402.
A vertical shift register, ie, a transfer electrode 405, is formed. Its main surface is via the insulating layer 406 and the transfer electrode 40.
5 are arranged. The photoelectric conversion region 403 and the buried channel 404 are separated by a channel stop region 407 made of a high p-type impurity layer.

The transfer gate region 40 is provided between the photoelectric conversion region 403 and the corresponding buried channel 404.
8 are arranged. Further, the area other than the photoelectric conversion region 403 is shielded from light by the metal layer 409. In order to suppress blooming, a substrate bias voltage VSUB411, which is a reverse bias voltage, is applied to the junction between the N-type semiconductor substrate 400 and the first region 401 and the second region 402 of the P well, and the photoelectric conversion region 4
This is realized by completely depleting (depletion layer) the first region 401 of the P well immediately below the P well 03. Further, by superimposing a high-potential pulse on VSUB as described above, forced discharge of all charges can be performed.

FIG. 3 shows the saturation signal amount (overflow level O) of the charge storage section with respect to the substrate bias voltage VSUB.
FL) change characteristics are shown. As shown, the overflow level OFL can be reduced by increasing the absolute value of the substrate bias voltage VSUB.

(Imaging Control Sequence 1) Hereinafter, a first example of the imaging control sequence at the time of continuous imaging of two images will be described with reference to the timing chart of FIG.

Here, the substrate bias value corresponding to the OFL is set to VSUB, and the superposed pulse at the time of discharging the electric charge is set to SUB.
We will distinguish them as pulses. To increase the saturation level, it is necessary to increase the OFL. However, this is not possible because excess charges overflow and blooming occurs. Therefore, the “OFL at the time of normal imaging” described below is set to the maximum level of the OFL within a range where blooming does not occur. The VSUB value corresponding to this is VN. Also, VD is a vertical synchronizing signal (however, it can be called a start reference signal of one frame operation because it is reset if necessary), V transfer is a vertical drive pulse for driving a vertical transfer path, The mechanical shutter indicates the open / closed state of the mechanical shutter 104.

When a shutter trigger (photographing start command) is input, an image capturing operation is started in synchronization with the first VD thereafter. A high-speed SUB pulse is output at the same time as a known high-speed charge discharge drive is started by the vertical drive pulse, thereby discharging unnecessary charges from the vertical transfer path and the charge storage unit. Then, at the start of the main exposure 1,
By outputting the final SUB pulse, the entire exposure for continuous imaging of two images is started. At this time, the mechanical shutter 104 has already been opened.

Subsequently, the first charge transfer pulse TG1 is output while the mechanical shutter 104 is kept open to transfer the photocharge to the vertical transfer path, thereby terminating the main exposure 1 and simultaneously completing the second main exposure 2 To start. At this time, in order to prevent the occurrence of line smearing, the reading of the first image obtained by the main exposure 1 has not yet started and is on standby, that is, the vertical drive pulse is stopped and the transfer of the signal charge is stopped.
Then, after the main exposure 2 is completed by the light shielding of the mechanical shutter 104, the transfer path driving for reading the first image by the main exposure 1 is started. Further, after the reading of the first image is completed, the second image by the main exposure 2 is transferred to the vertical transfer path by the second charge transfer pulse TG2, and then the transfer path driving for reading the image is started. As described above, since the transfer is not driven during the exposure, even if smear occurs in the first image, streaking does not occur. The reading of the second image is performed in a state where unnecessary charges such as smear do not exist at all in the transfer path due to the reading of the first image.

Here, as in the conventional case, when VSUB is fixed to the normal value VN, the first image read by TG1 is the same as the conventional one, but the second image is T after the end of the main exposure 2 (light shielding).
Since it takes several milliseconds to several tens of milliseconds until G2, the saturation level decreases.

In this example, the change of the VSUB setting is started after the light blocking by the mechanical shutter 104 is started, and before the light blocking is completed, VSUB has reached a lower VL from VN.
That is, in the period of the main exposure 1 before the output of the TG 1, the “OFL at the time of the normal imaging” is set. OFL ”is set to a higher level. Here, VL is a value several tens of percent lower than VN, and if it is lowered to this extent, the saturation level hardly decreases.

It should be noted that the set value of VSUB may be further reduced from VL after the light shielding is completed. Since there is no light after the light is blocked, the problem of blooming does not occur.
This is because there is no adverse effect on the image quality even if the value is increased.

During the transition period in which the shutter 104 is closed, the illuminance of the plate surface gradually decreases, so that it can be said that the transition period is from a bad influence of blooming to a bad influence of leak. On the other hand, lowering VSUB from VN to VL is equivalent to switching from the blooming suppression state to the leak suppression state. Therefore, it is necessary to start and complete the voltage switching during this period, As shown in the figure, gradually changing the value of VSUB in accordance with this period is a particularly effective control in the sense that a suppression effect according to the degree of occurrence of the failure can be obtained.

With the above-described imaging control, the saturation levels of two temporally adjacent images can be made the same as usual, so that the image quality of the two images can be kept equal. Although the occurrence of blooming due to the increase of the OFL is a concern for the time being, the control is performed without substantially causing a problem as described above. In addition, the exposure time of the main exposure 2 is set longer than that of the main exposure 1. This is because a good image portion is extracted from each of the two images and they are combined to obtain a recorded image with a wide dynamic range. That's why.

(Imaging Control Sequence 2) Next, a second example of the imaging control sequence at the time of continuous imaging of two images will be described with reference to the timing chart of FIG.

Here, VSUB is controlled so as not to be lower than VN. That is, since the saturation level is reduced in the second image, during exposure of the first image (until TG1 output is completed), VH corresponding to this low OFL is set, and VSUB is set immediately after TG1 output is completed. Change from VH to VN and reset to “OFL for normal imaging”. In this case, although the saturation levels of the two images are lower than usual, they can be kept equal. Also, there is no concern that blooming will increase.

Note that the decrease in the saturation level in the second image changes depending on the delay time from after light shielding to TG2, but this is constant during one frame period. ) May be set to a value of VH corresponding to this.

Also, if the change to VN is delayed by the main exposure 2
When the period becomes larger, the saturation level of the second image may decrease with the increase of the period, but can be usually ignored by the quick setting.

(Motion detection and averaging of two images)
Next, an example in which motion of a subject is detected as a function to which continuous imaging of two images by the above-described imaging control sequence 1 or 2 is applied will be described.

(1) First, an appropriate exposure is calculated by a known photometric unit included in the system controller 112 using an image pickup output of the preliminary preliminary exposure, and an exposure time t1 based on an aperture value to be used is determined. (2) After controlling the aperture to that value, imaging is performed by setting the exposure times of the main exposure 1 and the main exposure 2 to the same t1 by the imaging control 1 or 2.

(3) A motion vector (x, y) is obtained for the captured first and second images by correlation operation. Specifically, a reference window of a predetermined size is provided in the center of the first image, and has the same size as the reference window near the center of the second image, and the relative position coordinates from the reference window are (i, j). A plurality of detection windows are provided, and for each (i, j), the sum of the absolute values of the differences between the image signal of the reference window and the image signal of the detection window for each pixel is calculated, and the sum is minimized. (I, j) is obtained and set as a motion vector (x, y).

(4) The motion amount m is calculated as follows: m = (x2 + y2)
^Calculate by ^1/2 . (5) The shooting situation is determined based on m ≦ 2 (numerical value 2 is an example and can be set to an arbitrary value). In other words, the moving amount corresponds to image blurring (motion blurring).
If it is within the pixel, it is determined to be good. (6) An average calculation is performed for each pixel of the first image and the second image, and the result of the averaging is recorded as a recording image. (7) A warning is issued if “blur is large” in the above (5).

According to this embodiment, it is possible to obtain a high-quality image with reduced random noise by averaging two images, and not to lower the saturation level despite the use of the two-image photographing technique. Further, for example, a high-performance and high-quality camera that can more accurately detect and warn image blur caused by camera shake during shooting can be realized.

The continuous imaging of two images may be used only for motion detection, and the actual imaging for actually obtaining a recorded image may be performed by ordinary single imaging after continuous imaging of two images. In this case, as the exposure time t2 for single imaging, a value different from the exposure time t1 for each imaging in continuous imaging of two images can be used. Is m 'obtained by converting the exposure time ratio.
It is effective to use (m '= mxt2 / t1). That is, the amount of motion m detected by the continuous imaging of two images
Is converted into an exposure time at the time of actual imaging performed after continuous imaging of two images to obtain m ′, and whether or not m ′ ≦ 2 is detected to detect the degree of image blurring at the time of actual imaging. I do.

Further, in (6), a process for correcting a motion shift between the first and second images (for example, a (-x, -y) coordinate shift process for the entire second image) is added. ,
It can be configured to perform an average calculation of the two images after correcting the motion shift. As a result, a motion blur occurs only during a single exposure period, which is a very preferable modification.

It should be noted that, in addition to the above, various application examples such as the following can be considered. The mechanical shutter 104 may be kept open in advance, and exposure may be started by a SUB pulse. In this case, before the output of TG1, it is necessary to continuously drive the discharge of the transfer path, but the control of the mechanical shutter 104 can be simplified to only the closing operation. Of course, apart from this, it is also possible to start the exposure by opening the mechanical shutter 104 by changing the order of opening the mechanical shutter and outputting the final SUB pulse in the previous embodiment.

It is also possible to start the main exposure 2 after outputting a SUB pulse for forcibly discharging electric charges immediately after the output of TG1. (Including the above, if the end of the first exposure and the start of the second exposure are substantially simultaneous, the object is achieved.
It is included in the claims of the present invention. )

[0053]

As described above, according to the present invention,
While satisfying the condition that two images are obtained without a timing shift, it is possible to realize high-quality imaging without a decrease in the saturation level.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to an embodiment of the present invention.

FIG. 2 is an exemplary view showing a cross-sectional structure of an imaging device used in the imaging device of the embodiment.

FIG. 3 is a diagram showing a relationship between a substrate voltage and an overflow level of an image sensor used in the embodiment.

FIG. 4 is a timing chart showing a first imaging control sequence used in the embodiment.

FIG. 5 is a timing chart showing a second imaging control sequence used in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Imaging lens 102 ... Lens drive mechanism 103 ... Exposure control mechanism 104 ... Mechanical shutter 105 ... CCD color imaging element 106 ... CCD driver 107 ... Pre-process circuit 108 ... Digital process circuit 112 ... System controller

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C022 AA13 AB01 AB11 AC42 AC52 AC69 5C024 AX01 BX01 CX51 CX54 CX55 EX31 GY01 GZ01 HX09 HX10 HX12 HX14

Claims (5)

[Claims] A solid-state imaging device; a driving unit for driving the solid-state imaging device; an optical shutter unit capable of switching a transmission state and a light-shielding state of a subject image on an imaging surface of the solid-state imaging device; Means for controlling exposure and reading of an image signal by controlling the shutter means, and wherein the imaging control means changes from a light-shielded state by the shutter means to a transmission state when an image to be imaged is taken. Or the driving means outputs the final charge discharge pulse SUB in the transmission state of the shutter means, thereby starting all the exposures relating to the imaging, and switching the transmission state of the shutter means to the light-shielding state to thereby perform the imaging. With respect to the entire exposure, and during the period from the start of the full exposure to the end of the full exposure, A first charge transfer pulse TG1 output by the moving means to terminate the first exposure and to start a second exposure at the same time, and a first image generated by the first exposure The transfer path driving of the solid-state imaging device for signal reading is started after the end of the full exposure, and the second image generated by the second exposure after the reading of the first image signal is finished. A signal transfer means for transferring a signal to a transfer path of the solid-state imaging device by outputting the second charge transfer pulse TG2, and then driving a transfer path for reading the signal. The set value of the substrate bias voltage VSUB is controlled to a different value, and the overflow level determined according to the set value of the substrate bias voltage VSUB is set to the first charge transfer pattern. In the first exposure period before the output of the scan TG1, the first level is set to the first level, and in the period from the end of the total exposure to the output of the second charge transfer pulse TG2, the first level is higher than the first level. An imaging apparatus characterized in that the first image signal and the second image signal have the same saturation level after reading by setting each of the levels to at least two levels. 2. A change in the set level of the overflow level from a first level to a second level is started and completed within a transition period from a transmissive state to a light-shielded state of the shutter means upon completion of all exposures. The imaging device according to claim 1, wherein: 3. An exposure time is set equal between the first exposure and the second exposure, and the first image signal and the second
2. The imaging apparatus according to claim 1, further comprising: means for detecting a change in a subject based on a difference between the image signals. 4. An exposure time is set equal between the first exposure and the second exposure, and the first image signal and the second
2. The image pickup apparatus according to claim 1, further comprising a unit for averaging and outputting the image signals. 5. An imaging apparatus capable of continuously capturing two images using a solid-state imaging device, wherein the optical device is capable of switching between a transmission state and a light-shielding state of a subject image on an imaging surface of the solid-state imaging element. An objective shutter means for outputting the first charge transfer pulse TG1 during the entire exposure period for continuous imaging of the two images, thereby terminating the first exposure and simultaneously starting the second exposure, and The transfer path driving of the solid-state imaging device for reading out the first image signal generated by the first exposure starts after the end of the entire exposure period, and after the reading of the first image signal ends, After transferring the second image signal generated by the second exposure to the transfer path of the solid-state imaging device by outputting the second charge transfer pulse TG2,
Imaging control means for driving a transfer path for reading out the image data, wherein the imaging control means controls the solid-state imaging device in accordance with a transition from a transmission state to a light-shielded state of the shutter means upon completion of all exposures. The overflow level of the charge storage section is the first
Of the solid-state imaging device so as to gradually change from the level of
An imaging apparatus configured to control a set value of SUB.