JP2003324659A - Solid-state pickup device and electronic information apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state pickup device, wherein even if excessive light is incident upon a CCD, proper exposure control is facilitated to obtain a satisfactory display on a screen. <P>SOLUTION: There is provided a pseudo-OB clamp circuit 5, which reverses the phase of a reset pulse FR with respect to a horizontal transfer pulse FH1 in a part of a horizontal period, and generates a pseudo-OB signal at a level substantially equal to a black level (OB level), and further when a clamp pulse is supplied from a clamp pulse generator circuit 6, clamps the pseudo-OB signal. When excessive light is incident upon a CCD, transferred electric charges overflow an OB section, the electric charges are discharged to a reset drain RD following the phase inversion of the reset pulse FR to generate a pseudo-OB level substantially equal to the black level. By performing exposure control, taking the pseudo-OB level as a reference satisfactory screen display is ensured, without being influenced by the variations in the OB level. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device and an electronic information device using the solid-state image pickup device, such as a surveillance camera, a doorphone camera, a vehicle-mounted camera, a camera for a television phone and a camera for a mobile phone.

[0002]

2. Description of the Related Art Conventionally, a solid-state image sensor (Charge) has been used.
Various solid-state image pickup devices have been proposed, such as a solid-state image pickup device for a CCD camera that incorporates a Coupled Device (hereinafter abbreviated as CCD). FIG. 15 is a block diagram showing a schematic configuration of a conventional solid-state imaging device. This solid-state imaging device, as shown in FIG. 15, is an IT (Interl) that captures a subject image incident through a lens 51.
It has an ineTransfer type CCD 52.

16 (a) and 16 (b) are schematic views showing the basic structure of one chip of the CCD 52, respectively.

16 (a) and 16 (b), the CCD 52 has an effective pixel portion 72 on which light corresponding to a subject image (subject image light) is incident on a substrate 71.
Is provided. A plurality of photodiodes 74, which are photoelectric conversion elements, are two-dimensionally arranged in the vertical and horizontal directions in the effective pixel section 72, and an electric signal corresponding to a subject image is output. In addition, the effective pixel portion 72
OB (optical black) part 7 on one side
3 is provided. In the OB portion 73, a plurality of photodiodes 74, which are photoelectric conversion elements, are two-dimensionally arranged in the vertical direction and the horizontal direction, and are covered with a light shielding member 73a such as aluminum. As a result, the light corresponding to the subject image is blocked, the light is not incident on the photodiode 74 of the OB unit 73, and the electric signal (optical signal used as the optical black reference from the photodiode 74 of the OB unit 73). OB level signal) is output.

Further, in the CCD 52, a vertical CCD shift register 75 provided along each column of the photodiodes 74, and a horizontal CCD for transferring charges from the vertical CCD shift register 75 to a charge detection unit (output circuit) 77. And a shift register 76. The charges photoelectrically converted by the photodiode 74 and moved to the corresponding vertical CCD shift register 75 are the vertical transfer clock φ.
The horizontal CCD shift register 7 is synchronized with V1 to φV4.
6 are sequentially transferred. The charges transferred to the horizontal CCD shift register 76 are the horizontal transfer clocks φH1, φ.
In synchronization with H2, the charges are sequentially transferred to the charge detection unit 77 and output as an electric signal to the outside.

The signal output from the CCD 52 is shown in FIG.
As shown in, CDS (Correlated Double
e Sampling) circuit 53. The output signal from the CCD 52 in one horizontal period is the CDS circuit 5
When input to 3, the clock component included in the signal is CD
The noise is reduced by being removed by the S circuit 53.

The signal output from the CDS circuit 53 is O
It is input to the B clamp circuit 54. Among the output signals from the CCD 52 whose noise is reduced by the CDS circuit 53, the output signal (OB signal) from the OB unit 73 of the CCD 52 is clamped by the OB clamp circuit 54 and fixed at the direct current level. An OB level signal is generated which is used as an optical black reference. Also,
The output signal from the effective pixel section 72 of the CCD 52 is output at a level clamped with the signal level of the OB section 73 as a reference.

The signal output from the OB clamp circuit 54 is input to the video signal processing section 55. In the video signal processing unit 55, the output signal from the effective pixel unit 72
The signal level clamped by the B clamp circuit 54 (OB
Various processes are performed on the basis of (level). The video signal processing unit 55 includes an AGC (Automatic Gain).
A control circuit 56 is provided for the AGC.
In the circuit 56, the gain is controlled according to the strength of the signal input from the OB clamp circuit 54.

The output signal from the AGC circuit 56 is input to the correction processing circuit 57, and the gamma-corrected signal is output from the correction processing circuit 57. The output signal from the correction processing circuit 57 is input to the pedestal clamp circuit 58, and the input signal is clamped to the pedestal level in the pedestal clamp circuit 58. Pedestal clamp circuit 5
The output signal from 8 is input to the drive circuit 59, and the drive circuit 59 outputs a video signal suitable for a display device such as a television monitor as a video signal.

The signal output from the OB clamp circuit 54 is input to the detection circuit 60 and detected by the detection circuit 60. Based on the signal output from the detection circuit 60, a signal for controlling the iris of the CCD 52 and the exposure is output from the exposure control unit 61 to the CCD drive circuit 62. In the CCD drive circuit 62, the exposure controller 61
The CCD 52 is driven based on the signal output from the. In the exposure control unit 61 and the CCD drive circuit 62, the O
The signal level clamped by the B clamp circuit 54 (O
Each operation is performed based on (B level).
The exposure of the CCD 52 is controlled using, for example, an electronic shutter function provided in the CCD 52.

By the way, in recent years, the use of the solid-state image pickup device has been widespread, and the solid-state image pickup device as described above is also mounted on door phones, in-vehicle cameras and the like.
Since such a camera is often used for photographing the outdoors, excessive light such as sunlight may enter the CCD 52.

FIGS. 17A and 17B respectively show an output signal from the CCD 52, an output signal from the CDS 53, and a video signal from the drive circuit 59 during normal operation and incidence of excessive light. It is a graph which shows a waveform.

As shown in FIGS. 17A and 17B, in one horizontal period, an effective video signal period in which a signal corresponding to subject image light is output from the effective pixel section 72, and O
An OB period in which the OB signal corresponding to the black level is output from the B section 73 is provided. In the horizontal blanking period following the horizontal period, charges are transferred from the vertical transfer unit to the horizontal transfer unit. The reset pulse FR is a pulse for discharging the charges transferred from the horizontal transfer unit and converted into the charge-voltage by the detection unit to the reset drain RD.

In the normal operation shown in FIG. 17 (a),
During the effective video signal period, a signal (CCD output) corresponding to the subject image from the effective pixel section 72 is output from the CCD 52 and input to the CDS circuit 53, and a signal from which the clock component has been removed by the CDS circuit 53 is output. It Further, during the OB period, a signal (OB signal) corresponding to the black level from the OB portion 73 is output from the CCD 52 and the CDS is output.
The signal (CDS output), which is input to the circuit 53 and whose clock component is removed by the CDS circuit 53, is output.

The signal output from the CDS circuit 53 is O
It is input to the video signal processing unit 55 via the B clamp circuit 54. In the video signal processing unit 55, the O output from the OB unit 73 is applied to the signal output from the effective pixel unit 72.
Various processes are performed with the level of the B signal (OB level) as a reference, and a video signal is output (video output).

On the other hand, as shown in FIG. 17B, when excessive light is incident on the CCD 52, the effective pixel section 7
The signal output from the CCD 52 sharply increases in the middle of the effective video signal period in which the charge is output from the second photodiode, and the charge in the OB unit 73 is output during the OB period in the OB unit 73. The OB level indicating the amount of electric charge output from the photodiode is shown in FIG.
Changes to a level higher than the OB level output during normal operation. A signal from which the clock component has been removed is generated by the CDS circuit 53, and the video signal processing section 55 receives the output signal from the effective pixel section 72 from the OB section 7
Various processes are performed with the high-level signal from 3 as a reference. As a result, there is a problem that a dark screen is displayed even when a bright subject is imaged. CCD5
The reason why the OB level fluctuates in this way when excessive light is incident on 2 is as follows.

When excessive light is incident on the CCD 52, the charges generated in the light receiving portion (photodiode 74) of the effective pixel portion 72 correspond to the corresponding vertical CCD shift register 75.
Over the capacity of, and flows into the horizontal CCD shift register 76 during the scanning period of the horizontal CCD shift register 76.
Further, it exceeds the capacity of the horizontal CCD shift register 76 and overflows into the OB portion 73, which is a region where there is originally no photoelectrically converted charge. As a result, the OB level output from the OB unit 73 becomes higher than that in the normal operation and becomes a bright level different from the optical black reference. The screen will be depressed.

Further, in the video signal processing section 55, the OB level which has changed to a level higher than that in the normal operation is used as a reference.
Since the signal from the effective pixel section 72 is processed, the output of the video signal is at a lower level than it actually is. Therefore, the exposure control is performed so as to extend the exposure time for the CCD 52. As a result, the amount of light incident on the CCD 52 is further increased, and the electric charge overflowing to the OB portion 73 is further increased to deteriorate the display state.

As described above, in the above-described conventional solid-state image pickup device, even when a bright subject is imaged when the light amount is large, it looks black on the screen, and therefore when a light source having a light amount larger than a predetermined light amount is used. However, there is a problem that the subject cannot be recognized.

In order to solve this problem, for example, in Patent Document 1, the phase of the horizontal transfer pulse is changed in a part of the horizontal period of the solid-state image pickup device to generate a signal corresponding to a level substantially equal to the black level. , With reference to the generated signal,
A solid-state imaging device that controls the exposure amount of the CCD 52 is disclosed. According to this solid-state imaging device, excessive light is emitted from the CCD 5
Even when the light beam is incident on the beam 2, proper exposure control can be performed with reference to a signal corresponding to a level substantially equal to the black level.

[0021]

[Patent Document 1] Japanese Patent Laid-Open No. 10-210370

[0022]

However, the horizontal transfer pulse is used to sequentially transfer the charges of the CCD shift register 76 to the charge detection unit 77 in synchronization with the horizontal transfer clocks φH1 and φH2. Therefore, in the solid-state imaging device disclosed in Patent Document 1, it is necessary to change the phases of both pulses of the horizontal transfer clocks φH1 and φH2 in order to generate a signal corresponding to a level substantially equal to the black level. There is a problem that control becomes complicated.

The present invention has been made in order to solve the problems of the prior art as described above, and by simple control, even when excessive light is incident on the CCD, proper exposure control is performed, and good control is achieved. An object of the present invention is to provide a solid-state imaging device capable of obtaining a screen display and an electronic information device using the same.

[0024]

A solid-state image pickup device of the present invention detects a video signal and a black level signal photoelectrically converted by a solid-state image pickup device, and the black signal from the solid-state image pickup device is used as a reference for the video signal. In the solid-state imaging device that performs signal processing of the signal and resets the detected video signal and the black-level signal with a reset pulse, a pseudo black-level signal that is substantially equal to the black level is generated in the solid-state imaging device during a part of the signal reading period. So as to change at least one of the rising and falling timings of the reset pulse, and the exposure amount of the solid-state imaging device via the imaging device driving unit with reference to the pseudo black level signal. And an exposure control unit for controlling the same, thereby achieving the above object. Further, preferably, in the solid-state imaging device of the present invention, first clamp means for clamping a black level signal, second clamp means for clamping the pseudo black level signal, the first clamp means and the second clamp means. And a video signal processing unit that performs video signal processing on the video signal from the solid-state imaging device with the level of the signal clamped by any of the above as a reference.

Next, in the solid-state image pickup device of the present invention, a plurality of photoelectric conversion elements are arranged in the horizontal direction and the vertical direction, and an effective pixel portion for outputting an electric signal when subject image light is incident on each photoelectric conversion element, Also, a plurality of photoelectric conversion elements are arranged in the vertical direction around the effective pixel section, and the object image light is blocked from entering each photoelectric conversion element, and an optical black section that outputs an electric signal corresponding to a black level is provided. A solid-state image pickup device having: and a first level for clamping a black level signal output from an optical black portion of the solid-state image pickup device
At least one of the rising and falling timings of the reset pulse so as to cause the solid-state image sensor to generate a pseudo black level signal at a level substantially equal to the black level during a part of the horizontal period of the solid-state image sensor and the clamp means. The image pickup device driving unit for changing the image pickup device driving unit, the second clamp unit for clamping the generated pseudo black level signal, and the image pickup unit driving unit based on the level of the pseudo black level signal clamped by the second clamp unit. An exposure control unit for controlling the exposure amount of the solid-state image sensor via an effective pixel of the solid-state image sensor based on the level of the signal clamped by either the first clamp unit or the second clamp unit. And a video signal processing unit that performs video signal processing on the video signal output from the unit. That.

Usually, when excess light such as sunlight is incident on the solid-state image sensor, the electric black generated in the effective pixel section of the solid-state image sensor is a region where originally no electric charge is generated by photoelectric change. (OB part) overflows and the OB level generated in the OB part fluctuates from the normal operation. As a result, the OB level cannot be used as a reference for the optical black level.

According to the above structure, since at least one of the rising and falling timings of the reset pulse is changed (including waveform inversion or phase change) in a part of the horizontal period of the solid-state image pickup element, the solid-state image pickup element is changed. Even when excessive light such as sunlight is incident and electric charge overflows into the OB portion, the electric charge overflowing into the OB portion is once removed,
A signal (pseudo OB signal) corresponding to a level substantially equal to the original black level (OB level) is pseudo-generated. This pseudo OB signal is clamped by the second clamp means. The exposure controller controls the exposure of the solid-state image pickup device with reference to the signal of the pseudo OB level which is clamped by the second clamp means and is substantially equal to the original black level.

Therefore, by the relatively simple structure of adding the second clamp means to the general solid-state image pickup device and the relatively easy control of changing at least one of the rising and falling timings of the reset pulse, Even if excessive light is incident on the solid-state image sensor and the reference black level fluctuates, a pseudo black level (pseudo black level) that is substantially equal to the original black level (OB level) is not affected by such fluctuation. Appropriate exposure control can be performed based on the (OB level), and good screen display can be performed.

Further, the signal (OB signal) output from the OB portion of the solid-state image pickup device is clamped by the first clamp means. In the video signal processing section, the signal output from the effective pixel section of the solid-state image pickup device is processed with the signal level (OB level) clamped by the first clamping means as a reference. At this time, since the amount of light incident on the solid-state image sensor is controlled by the exposure control as described above,
The video signal processing that is performed based on the original black level (OB level) can also be appropriately performed.

Preferably, based on the control information from the exposure control section, a light amount detecting means for detecting whether or not the amount of light incident on the solid-state image pickup device is a predetermined amount or more, and the light amount detecting means, When it is detected that the amount of light incident on the solid-state image sensor is equal to or more than a predetermined amount, at least one of the rising and falling timings of the reset pulse is different from a part of the signal reading period (horizontal period). It further comprises pulse switching means for changing the pulse in a part of the period.

The pseudo black level (pseudo OB level)
Is a pseudo level substantially equal to the original black level (OB level) and is not exactly the same as the original black level. Therefore, it is desirable to perform the video signal processing with the original black level as much as possible.

When the amount of light incident on the solid-state image pickup device is less than a predetermined amount, for example, by performing maximum exposure control, the charges generated in the light receiving portion of the effective pixel portion are applied to the vertical CCD.
It is possible to prevent the OB unit from overflowing beyond the capacity of the shift register and the horizontal CCD shift register. As a result, the video signal processing can be properly performed based on the original black level. However, when the amount of light incident on the solid-state image sensor is equal to or more than a predetermined amount, even if the maximum exposure control is performed, the charge generated in the light receiving portion of the effective pixel portion overflows into the OB portion, and the OB level is exceeded. Fluctuates.

According to the above arrangement, when the quantity of incident light is detected to be equal to or more than the predetermined quantity by the quantity of light detecting means, the pulse switching means causes a part of the signal reading period (horizontal period) of the solid-state image pickup device. At least one of the rising and falling timings of the reset pulse is switched. As a result, the electric charge accumulated in the OB portion of the solid-state image sensor is once removed, and a signal (pseudo OB signal) corresponding to a level substantially equal to the original black level is generated from the OB portion. This pseudo OB signal is clamped by the first clamp means. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with reference to the pseudo black level (pseudo OB level) signal clamped by the first clamping means.

Therefore, a signal serving as a reference of the black level is generated according to the magnitude of the incident light amount when the image signal processing is performed, and the appropriate image signal processing can be performed according to the change of the incident light amount. . As a result, in particular, intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, and the charge generated in the light receiving section of the effective pixel section overflows into the OB section. Even in such a case, although it cannot be said to be sufficient, by performing the video signal processing with the pseudo black level as a reference, it is possible to avoid the worst situation in which the screen is dark and sunk, the screen is broken, and the like.

Preferably, in the solid-state image pickup device of the present invention, a light amount detecting means for detecting whether or not the amount of light incident on the solid-state image pickup device is equal to or more than a predetermined amount based on control information from the exposure control section, When the amount of light incident on the solid-state image sensor is detected by the light amount detection unit to be less than a predetermined amount, the output from the first clamp unit is input to the video signal processing unit, and is output to the solid-state image sensor. When it is detected that the amount of incident light is greater than or equal to a predetermined amount, the output from the second clamp means is input to the video signal processing unit so that the first
It has an output switching means for switching each output of the clamp means and the second clamp means.

Normally, when excess light such as sunlight is incident on the solid-state image sensor, the charges generated in the effective pixel section of the solid-state image sensor are originally photoelectrically converted, and there is no charge generated in the optical black section. Overflowed to (OB part), O
The OB level generated in the B section changes from the normal operation. As a result, the OB level cannot be used as a reference for the optical black level.

According to the above configuration, at least one of the rising and falling timings of the reset pulse is switched during a part of the signal reading period (horizontal period), so excessive light such as sunlight is incident on the solid-state image sensor. Even when the electric charge overflows to the OB portion, the electric charge overflowing to the OB portion is once removed, and a signal corresponding to a level substantially equal to the original black level (OB level) is artificially generated. This pseudo black level (pseudo OB level) signal is clamped by the second clamp means. In the exposure controller, the second clamp means clamps the
The exposure of the solid-state image sensor is controlled based on the pseudo black level signal.

Therefore, even if the excessive light is incident on the solid-state image sensor and the reference OB level fluctuates, a pseudo black level substantially equal to the original black level is obtained without being affected by such fluctuation. Exposure control can be performed as a reference, and good screen display can be performed. Further, since the amount of light incident on the solid-state image sensor is controlled by such exposure control, it is possible to properly perform video signal processing in which processing is performed based on the original black level.

When the light quantity detecting means detects that the quantity of light incident on the solid-state image sensor is less than the predetermined quantity, the output switching means inputs the output from the first clamp means to the video signal processing section. . In the video signal processing unit, the original black level (OB
Video signal processing can be properly performed based on the signal of (level).

Further, when the light quantity detecting means detects that the quantity of light incident on the solid-state image pickup device is equal to or more than a predetermined quantity, the output switching means outputs the output from the second clamp means to the video signal processing section. Is entered. In the video signal processing unit, the signal of the pseudo black level (pseudo OB level) clamped by the second clamp means is used as a reference.
The signal output from the effective pixel section of the solid-state image sensor is processed.

Therefore, when the video signal is processed, the signal serving as the reference of the black level is switched by the output switching means according to the magnitude of the incident light quantity, and the proper video signal processing is performed in accordance with the change of the incident light quantity. It can be carried out. As a result, in particular, intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, and the charge generated in the light receiving section of the effective pixel section overflows into the OB section. Even in such a case, although it cannot be said to be sufficient, by performing the video signal processing with the pseudo black level as a reference, it is possible to avoid the worst situation in which the screen is dark and sunk, the screen is broken, and the like.

For example, a change in at least one of the rising and falling timings of the reset pulse is
This is performed by either inverting the signal level of the reset pulse, holding the reset pulse at a constant level, or changing the phase of the reset pulse. With this, at the timing when the charges are transferred from the horizontal transfer unit to the charge detection unit (conversion unit),
Since the potential under the reset gate 11 of the charge detection unit (conversion unit) of the solid-state imaging device is low, the charges transferred from the horizontal transfer unit and leaking can be discharged to the reset drain.

Hereinafter, a part of the signal reading period (pseudo O
A case where the reset pulse is held at a constant level in the B period) and a period (OB period) different from the B period) will be described.

In the solid-state image pickup device of the present invention, a plurality of photoelectric conversion elements are arrayed in the horizontal and vertical directions, and an effective pixel portion for outputting an electric signal when light corresponding to a subject image is incident on each photoelectric conversion element, And a plurality of photoelectric conversion elements are arranged in the vertical direction around the effective pixel portion, and light corresponding to the subject image is blocked and does not enter each photoelectric conversion element,
A solid-state image pickup device having an optical black portion for outputting an electric signal corresponding to a black level, a first clamp means for clamping a signal outputted from the optical black portion of the solid-state image pickup element, and a clamp by the first clamp means Based on the level of the generated signal, a signal output from the effective pixel section of the solid-state image sensor, a video signal processing section that performs video signal processing, and a reset pulse in a part of the horizontal period of the solid-state image sensor. Second clamp means for holding the signal at a constant level, causing the solid-state imaging device to generate a signal corresponding to a level substantially equal to the black level, and clamping the generated signal, and the signal clamped by the second clamp means. The exposure control unit controls the exposure amount of the solid-state image pickup device with reference to the level of 1.

Usually, when excess light such as sunlight is incident on the solid-state image sensor, the charges generated in the effective pixel section of the solid-state image sensor are areas where there is originally no charge generated by photoelectric conversion. It also leaks to (OB part),
The OB level generated in the OB unit changes from the normal operation. As a result, the OB level cannot be used as a reference for the optical black level.

According to the above structure, since the reset pulse is held at a constant level during a part of the horizontal period of the solid-state image pickup device, excessive light such as sunlight is incident on the solid-state image pickup device and the OB portion is charged. Even if it overflows, the charge that overflows to the OB portion is once removed, and a signal corresponding to a level substantially equal to the original black level (OB level) (pseudo OB signal)
Is generated in a pseudo manner. This pseudo OB signal is clamped by the second clamp means. The exposure controller controls the exposure of the solid-state image pickup device with reference to the signal of the pseudo OB level which is clamped by the second clamp means and is substantially equal to the original black level.

Therefore, due to the relatively simple structure of adding the second clamp means to the general solid-state image pickup device and the relatively easy control of holding the reset pulse at a constant level, excessive light is transmitted to the solid-state image pickup element. Even if the reference black level fluctuates upon incidence, it is appropriate to use a pseudo black level (pseudo OB level) that is substantially equal to the original black level (OB level) as a reference, without being affected by such fluctuations. It is possible to perform various exposure controls and perform good screen display.

As described above, when changing at least one of the rising and falling timings of the reset pulse in a part of the horizontal period, the charge is transferred from the horizontal transfer unit to the charge detection unit though it is a short time. There is a time for transfer, charge-voltage conversion, and output as an output voltage. At this time, if excessive charges are transferred from the horizontal transfer unit to the charge detection unit, charge-voltage conversion may occur due to the overflowed charges. Further, when at least one of the rising and falling timings of the reset pulse is changed in a part of the horizontal period, the reset pulse becomes high level and the potential of the charge detection unit is reset to the same potential as the reset drain. , Since the time for discharging the charge to the reset drain is short, if the excessive charge transferred from the horizontal transfer unit is converted into the charge-voltage in the charge detection unit, the charge is not completely discharged to the reset drain, and the charge is discharged. There is a possibility that the level that remains in the detector and is clamped becomes unstable.

On the other hand, by holding the reset pulse at a constant level during a part of the horizontal period, it is possible to eliminate the time during which the charges are transferred from the horizontal transfer unit to the charge detection unit and converted into charges. Even if an excessive charge is transferred from the horizontal transfer section to the charge detection section, the charge can be sufficiently discharged to the reset drain.

Further, the signal (OB signal) output from the OB portion of the solid-state image pickup device is clamped by the first clamp means. In the video signal processing section, the signal output from the effective pixel section of the solid-state image pickup device is processed with the signal level (OB level) clamped by the first clamping means as a reference. At this time, since the amount of light incident on the solid-state image sensor is controlled by the exposure control as described above,
The video signal processing that is performed based on the original black level (OB level) can also be appropriately performed.

Further, preferably, based on the control information from the exposure control section, a light quantity detecting means for detecting whether or not the quantity of light incident on the solid-state image pickup device is a predetermined quantity or more, and the light quantity detecting means. When the amount of light incident on the solid-state imaging device is detected to be equal to or greater than a predetermined amount, the reset pulse is set to a constant level in another part of the horizontal period of the solid-state imaging device (different period; OB period). It further has pulse switching means for holding.

The above pseudo black level (pseudo OB level)
Is a pseudo level substantially equal to the original black level (OB level) and is not exactly the same as the original black level. Therefore, it is desirable to perform the video signal processing with the original black level as much as possible.

When the amount of light incident on the solid-state image pickup device is less than a predetermined amount, for example, by performing maximum exposure control, the charges generated in the light receiving portion of the effective pixel portion are applied to the vertical CCD.
It is possible to prevent the OB unit from overflowing beyond the capacity of the shift register and the horizontal CCD shift register. As a result, the video signal processing can be properly performed based on the original black level. However, when the amount of light incident on the solid-state image sensor is equal to or larger than a predetermined amount, even if the maximum exposure control is performed, the charge generated in the light receiving portion of the effective pixel portion overflows into the OB portion, and the OB level changes. To do.

According to the above construction, when the light quantity detecting means detects that the quantity of incident light is greater than or equal to the predetermined quantity, the pulse switching means switches the reset pulse during a part of the horizontal period of the solid-state image pickup device. Is maintained at a certain level. As a result, the electric charge accumulated in the OB portion of the solid-state image sensor is once removed, and a signal (pseudo OB signal) corresponding to a level substantially equal to the original black level is generated from the OB portion. This pseudo OB signal is clamped by the second clamp means. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with reference to the pseudo black level (pseudo OB level) signal clamped by the first clamping means.

Therefore, a signal serving as a reference of the black level is generated when the image signal processing is performed according to the magnitude of the incident light amount, and appropriate image signal processing can be performed according to the change of the incident light amount. . As a result, in particular, intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, and the charge generated in the light receiving section of the effective pixel section overflows into the OB section. Even in such a case, although it cannot be said to be sufficient, by performing the video signal processing with the pseudo black level as a reference, it is possible to avoid the worst situation in which the screen is dark and sunk, the screen is broken, and the like.

Further, preferably, there is further provided a level difference detecting means for detecting a level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means. .

When detecting the amount of light incident on the solid-state image sensor, the output voltage from the solid-state image sensor is detected by, for example, a detection circuit with reference to the level of the signal clamped by the second clamp means. When the output voltage is high based on the output voltage, exposure control (control of the electronic shutter etc.) is performed, then the electronic shutter speed is detected by the light amount detection means, and the magnitude of the incident light amount is judged by the speed value. You can In this case, since it takes time to detect the light amount, it is conceivable that an image bleeding or the like occurs during that time.

According to the above arrangement, the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means is detected, so that the level difference is equal to or more than the predetermined value. If there is a problem, it can be determined that no problem has occurred if the level difference is less than the predetermined value (or if there is no level difference). It is possible to determine whether or not there is, and the processing time can be shortened.

Further, it is preferable that the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means is equal to or more than a predetermined amount by the level difference detection means. Pulse reset means for holding the reset pulse at a constant level during another partial period of the horizontal period of the solid-state image sensor when it is detected that

The above pseudo black level (pseudo OB level)
Is a pseudo level substantially equal to the original black level (OB level) and is not exactly the same as the original black level. Therefore, it is desirable to perform the video signal processing with the original black level as much as possible.

According to the above construction, instead of detecting the incident light quantity by the light quantity detecting means, the first difference is obtained by using the level difference detecting means.
The level difference between the level of the signal clamped by the clamp means and the level of the signal clamped by the second clamp means is detected, and when the level difference is less than a predetermined amount, for example, maximum exposure control is performed. By doing so, the electric charge generated in the light receiving portion of the effective pixel portion exceeds the capacity of the vertical CCD shift register and the horizontal CCD shift register and O
It is possible to avoid overflowing into the B section. As a result, the video signal processing can be properly performed based on the original black level. However, when the level difference is equal to or more than the predetermined amount, even if the maximum exposure control is performed, the charges generated in the light receiving portion of the effective pixel portion overflow into the OB portion,
Level fluctuates.

Therefore, when it is detected that the level difference is equal to or more than the predetermined amount, the pulse switching means
The reset pulse is switched and held at a constant level during a part of the horizontal period of the solid-state image sensor. This allows
The electric charge accumulated in the OB portion of the solid-state image sensor is once removed, and a signal (pseudo OB signal) corresponding to a level substantially equal to the original black level is generated from the OB portion. This pseudo OB
The signal is clamped by the first clamping means. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with reference to the pseudo black level (pseudo OB level) signal clamped by the first clamping means.

Therefore, it is judged whether or not there is a problem due to the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means, and according to the result. As a result, a signal serving as a reference of the black level is generated when the video signal processing is performed, and the proper video signal processing can be performed. As a result, in particular, intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, and the charge generated in the light receiving section of the effective pixel section overflows into the OB section. Even in such a case, although it cannot be said to be sufficient, by performing the video signal processing with the pseudo black level as a reference, it is possible to avoid the worst situation in which the screen is dark and sunk, the screen is broken, and the like.

Further, preferably, based on the control information from the exposure control section, a light quantity detecting means for detecting whether or not the quantity of light incident on the solid-state image pickup element is a predetermined quantity or more, and the level difference detecting means. Detects that the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means is a predetermined amount or more, and the light amount detection means Detects that the amount of light incident on the solid-state imaging device is greater than or equal to a predetermined amount, and the level difference detection means detects the level of the signal clamped by the first clamp means and the second clamp. It is detected that the level difference from the level of the signal clamped by the means is less than a predetermined amount, and the amount of light incident on the solid-state imaging device is more than a predetermined amount by the light amount detection means. If there it is detected, further comprising a pulse switching means for holding a reset pulse, a constant level in the other partial period of a horizontal period of the solid-state imaging device (another period).

When the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means is close to a predetermined amount, the first
Since the normal OB signal level output from the clamp means and the pseudo OB signal level output from the second clamp means are not at the same level, a sense of discomfort may occur when the screen changes. In addition, when the level difference is greater than or equal to the predetermined amount and less than or equal to the predetermined amount, the image based on the normal OB level output from the first clamp unit and the second clamp unit are output. And the image based on the pseudo OB level
Image defects such as flicker may occur.

According to the above structure, the level difference detecting means detects the level difference between the level of the signal clamped by the first clamping means and the level of the signal clamped by the second clamping means. If the level difference is greater than or equal to a predetermined amount, a problem has occurred, and if the level difference is less than the predetermined amount, it can be determined that no problem has occurred, and the incident light amount is greater than or equal to a predetermined amount by the light amount detection means. It is possible to perform pulse switching with higher accuracy by detecting whether or not As a result, even when excessive light such as sunlight is incident on the solid-state image sensor, it is possible to properly perform exposure.

Preferably, in the solid-state image pickup device of the present invention, the level difference detection means determines the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means. When it is detected that the amount is less than the predetermined amount, the output from the first clamp means is input to the video signal processing unit, and the level of the signal clamped by the first clamp means and the second clamp means are supplied to the second clamp means. So that the output from the two clamping means is input to the video signal processing unit when it is detected that the level difference from the level of the clamped signal is a predetermined amount or more.
It has a switching means for switching between the first clamping means and the second clamping means.

Usually, when excess light such as sunlight is incident on the solid-state image sensor, the charges generated in the effective pixel section of the solid-state image sensor are areas where there is originally no charge generated by photoelectric conversion. It overflows into (OB part),
The OB level generated in the OB unit changes from the normal operation. As a result, the OB level cannot be used as a reference for the optical black level.

According to the above configuration, since the reset pulse is held at a constant level during a part of the horizontal period of the solid-state image pickup device, excessive light such as sunlight is incident on the solid-state image pickup device and the OB portion is charged. Even when it overflows, the charge that overflows to the OB portion is once removed, and a signal corresponding to a level substantially equal to the original black level (OB level) is generated in a pseudo manner. This pseudo black level (pseudo OB level) signal is clamped by the second clamp means. In the exposure controller, the second clamp means clamps the
The exposure of the solid-state image sensor is controlled based on the pseudo black level signal.

Therefore, even if excessive light is incident on the solid-state image sensor and the reference OB level fluctuates, a pseudo black level substantially equal to the original black level is obtained without being affected by such fluctuation. Exposure control can be performed as a reference, and good screen display can be performed. Further, since the amount of light incident on the solid-state image sensor is controlled by such exposure control, it is possible to properly perform video signal processing in which processing is performed based on the original black level.

Further, the level difference detection means detects the level difference between the first signal level clamped by the first clamp means and the second signal level clamped by the second clamp means, to determine whether there is a defect. When it is determined that the level difference is less than the predetermined amount, the output switching unit inputs the output from the first clamp unit to the video signal processing unit. The video signal processing section can properly perform the video signal processing based on the original black level (OB level) signal clamped by the first clamping means.

Further, the level difference between the first signal level clamped by the first clamp means by the level difference detection means and the second signal level clamped by the second clamp means may be a predetermined amount or more. When detected, the output from the second clamp means is input to the video signal processing section by the output switching means. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with the pseudo black level (pseudo OB level) signal clamped by the second clamping means as a reference.

Therefore, it is judged whether or not there is a problem due to the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means, and the result is determined according to the result. As a result, a signal serving as a reference of the black level is generated when the video signal processing is performed, and the proper video signal processing can be performed. As a result, in particular, intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, and the charge generated in the light receiving section of the effective pixel section overflows into the OB section. Even in such a case, although it cannot be said to be sufficient, by performing the video signal processing with the pseudo black level as a reference, it is possible to avoid the worst situation in which the screen is dark and sunk, the screen is broken, and the like.

Preferably, in the solid-state image pickup device of the present invention, level difference detection for detecting the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means. Means, a light quantity detection means for detecting whether or not the quantity of light incident on the solid-state image pickup device is equal to or more than a predetermined quantity based on control information from the exposure control section, and the level difference detection means for the first clamp means. It is detected that the level difference between the level of the signal clamped by the second clamp means and the level of the signal clamped by the second clamp means is less than a predetermined amount, and the light quantity detection means directs the solid-state image sensor. When it is detected that the amount of incident light of the light is less than a predetermined amount, the output from the first clamp means is input to the video signal processing section, and the level difference detection means causes the first clamp It is detected that the level difference between the level of the signal clamped by the second clamp means and the level of the signal clamped by the second clamp means is equal to or greater than a predetermined amount, and the light amount detection means detects the solid-state image. When it is detected that the amount of light incident on the device is greater than or equal to a predetermined amount,
And the level difference detection means detects that the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means is less than a predetermined amount, Further, when the light quantity detecting means detects that the quantity of light incident on the solid-state image sensor is equal to or more than a predetermined quantity, the output from the second clamping means is input to the video signal processing section. It has an output switching means for switching each output of the first clamp means and the second clamp means.

When the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means is close to a predetermined amount, the first
Since the normal OB signal level output from the clamp means and the pseudo OB signal level output from the second clamp means are not at the same level, a sense of discomfort may occur when the screen changes. Further, when the level difference is repeatedly equal to or more than the predetermined amount and less than the predetermined amount, the screen is based on the image based on the output from the first clamp means and the output from the second clamp means. It is conceivable that an image defect such as flicker may occur due to the switching between the image and the image.

According to the above configuration, the level difference detecting means detects the level difference between the level of the signal clamped by the first clamping means and the level of the signal clamped by the second clamping means. If the level difference is greater than or equal to a predetermined amount, a problem has occurred, and if the level difference is less than the predetermined amount, it can be determined that no problem has occurred, and the incident light amount is greater than or equal to a predetermined amount by the light amount detection means. By detecting whether or not
The outputs of the clamp means and the second clamp means can be switched. As a result, even when excessive light such as sunlight is incident on the solid-state image sensor, video signal processing can be properly performed.

For example, the reset pulse is set to a voltage at which the potential of the charge detection unit is reset to the same potential as the reset drain in a partial period of the horizontal period (signal reading period) or another partial period of the horizontal period. Is set. As a result, the potential of the charge detection unit (conversion unit) of the solid-state imaging device is reset to the same potential as the reset drain, and the charges transferred from the horizontal transfer unit and leaked can be completely discharged to the reset drain.

Further, a part of the horizontal period (signal reading period) can be set, for example, during or after a signal is output from the optical black portion in the solid-state image pickup device. Further, another partial period of the horizontal period (signal reading period) is also set to a period in which a signal is output from the optical black portion of the solid-state image sensor, for example. Further, preferably, this another partial period may be set before a partial period of the horizontal period (signal reading period).

[0079]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments 1 to 1 of the present invention will be described below.
10 will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing a configuration of a solid-state imaging device according to Embodiment 1.

This solid-state image pickup device, as shown in FIG.
CCD 1 as a solid-state image sensor, CDS circuit 2, O
B clamp circuit 3, clamp pulse generation circuit 4, pseudo OB clamp circuit 5, and clamp pulse generation circuit 6
A video signal processing unit 7, a detection circuit 8 and an exposure control unit 9
And a CCD drive circuit 10 as an image pickup element drive means. The OB clamp circuit 3 and the clamp pulse generation circuit 4 constitute a first clamp means. Further, the pseudo OB clamp circuit 5 and the clamp pulse generation circuit 6 constitute second clamp means.

The CCD 1 is, for example, an IT type CCD,
A subject image incident through a lens (not shown) is captured. Similar to the conventional CCD 52 shown in FIGS. 16A and 16B, the CCD 1 is provided with an effective pixel portion 72 on which light corresponding to a subject image (subject image light) is incident on a substrate 71. ing. In the effective pixel section 72,
A plurality of photodiodes 74, which are photoelectric conversion elements, are two-dimensionally arranged in the vertical direction and the horizontal direction, and an electric signal corresponding to a subject image is output. Further, an OB (optical black) portion 73 is provided on one side of the effective pixel portion 72. In the OB portion 73, a plurality of photodiodes 74, which are photoelectric conversion elements, are arranged in the vertical direction and the horizontal direction, and are covered with a light shielding member 73a such as aluminum. As a result, the light corresponding to the subject image is blocked and is not incident on the photodiode 74 of the OB unit 73, and an electric signal (OB signal) used as an optical black reference is output from the photodiode 74 of the OB unit 73. ) Is output.

The CCD 1 has a photodiode 7
A vertical CCD shift register 75 provided along each of the four columns and a horizontal CCD shift register 76 for transferring the charge from the vertical CCD shift register 75 to the charge detection unit (output circuit) 77 are provided. Photodiode 7
The electric charges photoelectrically converted by 4 and transferred to the corresponding vertical CCD shift register 75 are the vertical transfer clock φV.
Horizontal CCD shift register 76 in synchronization with 1 to φV4
Are sequentially transferred in the direction of. Horizontal CCD shift register 7
The charges transferred to 6 are the horizontal transfer clocks φH1 and φH.
In synchronism with 2, the charges are sequentially transferred to the charge detection unit 77 and output to the outside as an electric signal.

FIG. 2 is a signal waveform diagram showing the relationship between the horizontal transfer pulses (horizontal transfer clocks) FH1 and FH2 and the reset pulse FR in the solid-state image pickup device of the first embodiment, and FIG. It is an enlarged view of the A part of (a), It is a signal waveform diagram which shows the drive timing of CCD.

When an image of a subject incident through a lens (not shown) is picked up by the CCD 1, horizontal transfer pulses FH1 and FH2 as shown in FIGS. 2 (a) and 2 (b) and a reset pulse FR cause A signal having a waveform as shown in FIG. 2B is output from the CCD 1.
In this figure, the mesh part in the CCD output signal is
As an electric signal, a voltage obtained by voltage conversion of the electric charge in the electric charge detection unit 77 is shown.

The signal output from the CCD 1 (CCD output) is input to the CDS circuit 2. When the output signal from the CCD 1 in one horizontal period is input to the CDS circuit 2, the clock component included in the signal is removed by the CDS circuit 2 and noise is reduced.

The signal from which the clock component has been removed by the CDS circuit 2 is input to the OB clamp circuit 3 as the first clamp means. The clamp pulse generation circuit 4 is connected to the OB clamp circuit 3, and the clamp pulse CP1 is supplied from the clamp pulse generation circuit 4 in the OB period as shown in FIGS. 2A and 2B. OB of the CCD 1 input from the CDS circuit 53 when
The output signal (OB signal) from the unit 73 is clamped by the OB clamp circuit 3 and fixed at the DC level.
This allows the OB to be used as the optical black reference.
A level signal is generated. Further, the output signal from the effective pixel section 72 of the CCD 1 is output at a level clamped with the signal level of the OB section 73 as a reference.

The OB level signal output from the OB clamp circuit 3 is input to the video signal processing section 7. In the video signal processing unit 7, various processes are performed on the output signal from the effective pixel unit 72 with the OB level signal clamped by the OB clamp circuit 3 as a reference. The video signal processing unit 7 includes, like the conventional solid-state imaging device shown in FIG.
An AGC circuit is provided, and in the AGC circuit, the gain is controlled according to the strength of the signal input from the OB clamp circuit 3. The output signal from the AGC circuit is input to the correction processing circuit, and the gamma-corrected signal is output from the correction processing circuit. The output signal from the correction processing circuit is input to the pedestal clamp circuit, and the input signal is clamped to the pedestal level in the pedestal clamp circuit. An output signal from the pedestal clamp circuit is input to a drive circuit, and a video signal suitable for a display device such as a television monitor is output from the drive circuit as a video signal.

The signal from which the clock component has been removed by the CDS circuit 2 is a pseudo O as the second clamp means.
It is also input to the B clamp circuit 5.

As shown in FIGS. 2A and 2B, in a part of the horizontal period of the CCD 1 (pseudo OB period), the reset pulse FR rises and rises with respect to the rise of the horizontal transfer pulse FH1. At least one of the falling timings is changed, in this case, the signal level of the reset pulse FR is inverted (or changed by advancing or delaying the phase), and all the charges overflowing in the OB portion 73 are discharged to the reset drain RD. A control signal for inverting the signal level of the reset pulse FR is not output from the pseudo OB clamp circuit 5 to the CCD drive circuit 10. For example, the CCD driving circuit 10 controls the CCD 1 to invert the signal level of the reset pulse FR.
Is. As a result, a pseudo signal (pseudo OB signal) corresponding to a level substantially equal to the black level is generated and CC
It is output from D1.

A clamp pulse generation circuit 6 is connected to the pseudo OB clamp circuit 5, and the clamp pulse generation circuit 6 outputs the clamp pulse CP during the pseudo OB period.
2 is supplied, the pseudo OB signal is
It is clamped by the clamp circuit 5 and fixed at the DC level. As a result, a signal of a pseudo OB level that is substantially equal to the original black level (OB level) is generated.

FIG. 3A is a signal waveform diagram showing the driving timing of the CCD in the solid-state imaging device of the first embodiment, and FIG. 3B is a schematic diagram showing the potential of the horizontal transfer charge of the CCD. is there. In this figure, CC
The mesh portion in the D output signal indicates the transfer charge amount.

3A and 3B, in the effective video signal period in which the signal from the effective pixel section 72 is output, at the time t1, the horizontal transfer pulse FH1 is at the high level and the horizontal transfer pulse FH2 is at the high level. It becomes a low level, and charges are transferred in the direction of the output gate OG in the horizontal CCD shift register 76. Further, a high level (a level) reset pulse FR is applied to the reset gate 11, and the potential of the conversion unit 12 is reset to the reset drain RD.
Is reset to the same potential as.

At time t2, the reset pulse FR becomes low level (b level) and the potential under the reset gate 11 becomes low (shallow), but the potential of the conversion section 12 is at the same level as the potential at time t1. . At the times t1 and t2, the reset gate 11 is thus induced by the induction of the reset pulse FR.
There is a difference in the potential below.

At time t3, the horizontal transfer pulse FH1 goes low and the horizontal transfer pulse FH2 goes high,
The potential under the transfer electrode to which FH1 is added transits to a low (shallow) level, and the potential under the transfer electrode to which FH2 is applied transits to a high (deep) level. The potential under the transfer electrode to which FH1 is applied is the output gate OG.
The potential becomes lower (shallow) than the lower potential, and the charges are transferred to the conversion unit 12 (the charge detection unit 77 in FIG. 16B). Due to the charges thus transferred, the potential of the conversion unit 12 changes, and this potential change serves as a signal output in the CCD 1.
Read from.

Next, in the pseudo OB period, at time t4, the horizontal transfer pulse FH1 becomes high level and the horizontal transfer pulse FH2 becomes low level, and charges are transferred in the horizontal CCD shift register 76 toward the output gate OG. Further, the reset pulse FR remains low level (b level).

At time t5, the reset pulse FR is at high level (a level), the potential under the reset gate 11 becomes high (deep), and the potential of the conversion section 12 is reset to the potential equal to the reset drain RD. .

At time t6, the horizontal transfer pulse FH1 becomes low level and the horizontal transfer pulse FH2 becomes high level,
When the potential under the transfer electrode to which the horizontal transfer pulse FH1 is applied is low (shallow), the horizontal transfer pulse FH2 is applied.
High potential under the transfer electrode (deep)
Transition to level. The potential under the transfer electrode to which the horizontal transfer pulse FH1 is applied becomes lower (shallow) than the potential under the output gate OG, and charges are transferred to the conversion unit 12, but the potential under the reset gate 11 becomes high (deep). Therefore, all the charges transferred to the conversion unit 12 are discharged to the reset drain RD. As a result, even when excessive light is incident on the CCD 1, a pseudo OB signal is obtained during the pseudo OB period, which is substantially the same as when there is no charge that overflows the transfer to the OB portion 73.

The pseudo OB level signal output from the pseudo OB clamp circuit 5 is input to the detection circuit 8 and detected by the detection circuit 8. Based on the signal output from the detection circuit 8, a signal for controlling the iris and exposure of the CCD 1 is output from the exposure control section 9 to the CCD drive circuit 10.
Is output to. In the CCD drive circuit 10, the exposure controller 9
The CCD 1 is driven based on the signal output from the CCD 1. The exposure control unit 9 and the CCD drive circuit 10 perform their respective operations on the basis of the signal level (pseudo OB level) clamped by the pseudo OB clamp circuit 5. The exposure of the CCD 1 is controlled using, for example, an electronic shutter function provided in the CCD 1.

As described above, in the solid-state image pickup device of the present embodiment, even if the excessive light is incident on the CCD 1 and the OB level, which is an optical black reference, fluctuates, the pseudo black level is substantially equal to the original black level. The appropriate exposure control can be performed according to the objective OB level. As a result, a good screen display can be obtained even when excessive light is incident on the CCD 1.

The pseudo OB level cannot be said to be exactly the same level as the original black level (OB level) due to the influence of the induction by the reset pulse FR and so on. Is not suitable. Therefore, in the present embodiment, only the exposure control is performed on the basis of the pseudo OB level, and the video signal processing is performed on the basis of the OB level, not the pseudo OB level. Since the amount of light incident on the CCD 1 is adjusted by such exposure control based on the pseudo OB level, it is possible to properly perform the video signal processing that is performed based on the OB level. (Second Embodiment) In the first embodiment, the reset pulse F
The pseudo OB clamp circuit 5 clamps a pseudo black level signal generated by changing at least one of the rising and falling timings of R (inversion or phase change of the signal level), and exposure is performed using this pseudo black level signal as a reference. In the case of performing control (corresponding to claims 1 to 3), in the second embodiment, in addition to this, as a reference black level signal for performing signal processing in the video signal processing unit 7 according to the incident light amount. , When switching the outputs of the OB clamp circuit 3 and the pseudo OB clamp circuit 5 (corresponding to claim 4)
Is.

FIG. 4 is a block diagram showing the structure of the solid-state image pickup device according to the second embodiment. In addition, in this figure, the components having the same functions as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

This solid-state image pickup device has a light amount detecting section 21 in addition to the configuration of the solid-state image pickup device of the first embodiment shown in FIG.
A signal switching unit 22 as output switching means is provided.

The light amount detector 21 detects the amount of light incident on the CCD 1 according to the control information from the exposure controller 9. The exposure control unit 9 controls the electronic shutter of the CCD 1 so that the output signal level from the CCD 1 becomes constant. Therefore, the light amount detection unit 21 can determine whether the incident light amount is equal to or more than the predetermined amount, depending on whether the electronic shutter speed of the CCD 1 is equal to or more than the predetermined value.

When the amount of incident light detected by the light amount detecting unit 21 is less than the predetermined amount, the signal switching unit 22 switches the switch and the output from the OB clamp circuit 3 is input to the video signal processing 7. It In the video signal processing unit 7, various signal processings are performed on the basis of the OB level signal output from the OB clamp circuit 3, as in the first embodiment.

The pseudo OB level is a pseudo level of the original black level (original OB level), and is not exactly the same level as the original OB level. Therefore, it is desirable to output the video signal with the original OB level as a reference as much as possible. Therefore, when the amount of incident light is less than a predetermined amount, for example, by performing maximum exposure control, the OB
Since the electric charge can be prevented from overflowing to the portion 73, the video signal processing can be properly performed with the original OB level as a reference.

On the other hand, when the amount of incident light detected by the light amount detector 21 is not less than the predetermined amount, the signal switching unit 22
The switch is switched by, and the pseudo OB clamp circuit 5
Is input to the video signal processing 7. In the video signal processing unit 7, various signal processing is performed with the pseudo OB level signal output from the pseudo OB clamp circuit 5 as a reference.

The reason why the pseudo OB level is used in this way is that when the incident light amount is a predetermined amount or more, the electric charge overflows into the OB portion 73 even if the maximum exposure control is performed, and
This is because the B level changes.

In the exposure control unit 9, the original black level (original O level) obtained by the pseudo OB clamp circuit 5 is obtained as in the first embodiment regardless of the detection result of the light amount detection unit 21.
Exposure control is performed on the basis of a pseudo OB level which is substantially equal to the (B level), and the CCD drive circuit 10 controls the electronic shutter of the CCD 1.

As described above, in the solid-state image pickup device of the second embodiment, the signal switching unit 22 sets the optical black reference level at the time of performing the image signal processing depending on the amount of light incident on the CCD 1. Can be switched by
Appropriate video signal processing can be performed in response to changes in the amount of incident light. As a result, in particular, even if intense light is incident on the CCD 1 such that the overflow of charges to the OB portion cannot be avoided even if the maximum exposure control is performed, the pseudo OB
Since the video signal processing can be performed on the basis of the level, it cannot be said to be sufficient, but it is possible to avoid the worst situation such as the screen sinking black or the screen failing.

In the second embodiment, the outputs of the OB clamp circuit 3 and the pseudo OB clamp circuit 5 are switched as the reference black level signal which is processed by the video signal processing unit 7 according to the amount of incident light. I explained the case,
The pseudo OB clamp circuit 5 and the OB clamp circuit 3 are used as reference black level signals for performing exposure control according to the amount of incident light.
It is also conceivable to switch each output of. (Third Embodiment) In the third embodiment, the above-described first and second embodiments are performed.
In addition, in the OB period (a partial period other than the partial period (pseudo OB period) of the horizontal period), at least one of the rising and falling timings of the reset pulse FR when the incident light amount is equal to or more than a predetermined amount. This is a case in which the OB clamp circuit 3 is clamped by the pseudo black level signal by changing the value (for example, inverting the signal level or changing the phase).

FIG. 5 is a block diagram showing the structure of the solid-state image pickup device according to the third embodiment. In this figure, constituent members having the same functions as those in the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted.

This solid-state image pickup device has a light amount detecting section 21 in addition to the configuration of the solid-state image pickup device of the first embodiment shown in FIG.
And a pulse switching unit 23. Light intensity detector 21
Then, similarly to the second embodiment, the amount of light incident on the CCD 1 is detected according to the control information from the exposure controller 9. In the pulse switching unit 23, when the incident light amount detected by the light amount detection unit 21 is equal to or more than a predetermined amount, the phase of the reset pulse FR is switched (or the signal level is changed) in a part of the horizontal period (OB period) of the CCD 1. Flipped).

FIG. 6 is a signal waveform diagram showing the drive timing of the solid-state imaging device of this embodiment.

If the amount of incident light detected by the light amount detector 21 is less than the predetermined amount, as in the first embodiment,
During the OB period, the phase of the reset pulse FR is not switched, and the original black level (OB level) signal clamped by the clamp pulse CP1 is output from the OB clamp circuit 3. In the video signal processing section 7, similar to the first embodiment, various signal processings are performed with the original OB level signal output from the OB clamp circuit 3 as a reference.

On the other hand, when the amount of incident light detected by the light amount detector 21 is equal to or more than the predetermined amount, the pulse switching unit 2
6, the phase of the reset pulse FR is inverted with respect to the rising of the horizontal transfer pulse FH1 in a part of the horizontal period of the CCD 1 (OB period), as shown in FIG.
All the charges overflowing into the B part 73 are reset drain RD.
Is discharged to. As a result, a pseudo signal (pseudo OB signal) corresponding to a level substantially equal to the black level is generated and output from the CCD 1. OB during the OB period
When the clamp pulse CP1 is supplied to the clamp circuit 3, the pseudo OB signal is clamped by the OB clamp circuit 3 and fixed at the DC level. As a result, a pseudo OB that is substantially equal to the original black level (OB level)
A level signal is generated. In the video signal processor 7,
Various processes are performed with the pseudo OB level signal output from the B clamp circuit 3 as a reference.

In the exposure controller 9, the pseudo OB clamp circuit 5 is supplied when the clamp pulse CP2 is supplied, regardless of the detection result of the light amount detector 21, as in the first embodiment.
Exposure control is performed on the basis of a pseudo OB level that is substantially clamped at the original black level (OB level), and the CCD drive circuit 10 controls the electronic shutter of the CCD 1.

As described above, in the solid-state image pickup device according to the third embodiment, the level serving as an optical black reference is generated when the image signal processing is performed depending on the amount of light incident on the CCD 1. Appropriate video signal processing can be performed in response to changes in the amount of incident light. As a result, in particular, even if intense light is incident on the CCD 1 such that electric charge overflow to the OB portion cannot be avoided even if the maximum exposure control is performed, the image signal processing is performed with the pseudo OB level as a reference. Since it is possible to perform the above, it is not sufficient, but it is possible to avoid the worst situation such as the screen sinking black or the screen collapsing.

By the way, in the solid-state image pickup device of each of the first to third embodiments, by changing the phase of the reset pulse in a part of the horizontal period, even when excessive light is incident on the CCD 1, proper exposure control is performed. Is done.

However, as shown in FIG. 3A, when the potential level of the reset pulse FR is inverted, the charge is transferred from the horizontal transfer section at a short time, for example, from time t7 to time t8. Detection unit (conversion unit: output circuit) 77
When the charge is converted to a voltage and output as an output voltage from the CCD 1, an excessive charge is transferred from the horizontal CCD shift register 76 to the charge detection unit 77 to the charge detection unit (output circuit) 77. Then, charge-voltage conversion is performed by the overflowed charges.

Further, the horizontal CCD shift register 7
The charge transferred from 6 is converted into a charge voltage by the detection unit (charge detection unit) 12, the reset pulse FR becomes high level from time t8 to time t9, and the reset gate 1
When a high-level (a-level) reset pulse FR is applied to 1 and the potential of the conversion unit 12 is reset to a potential equal to the reset drain RD, charges are discharged to the reset drain RD. At this time, if an excessive amount of electric charge is transferred, the electric charge may not be completely discharged to the reset drain RD in a short time from time t8 to time t9, and electric charge may remain in the detection unit 12, and the level of the signal to be clamped. May become unstable.

Further, in the solid-state image pickup device of each of the first to third embodiments, the detection circuit 8 detects the output voltage from the CCD 1 with the level of the signal clamped by the second clamp means as a reference, and the output voltage thereof is detected. After performing the exposure control (control of the electronic shutter etc.) when the output voltage is large based on, the light quantity detection unit detects the electronic shutter speed,
Since it is determined by the speed value whether or not the light amount is more than a predetermined amount, it takes a lot of processing time to determine whether or not there is a problem due to excessive light being incident, and during that time there is a problem such as an image bleeding. May occur.

Therefore, in each of the following fourth to tenth embodiments,
A solid-state imaging device capable of solving the above problems will be described. (Fourth Embodiment) In the first to third embodiments, at least one of the rising and falling timings of the reset pulse is changed (inversion of signal level or phase change) in a part of the horizontal period (for example, pseudo OB period). However, in the fourth embodiment, the reset pulse FR is held at a predetermined constant level during a part of the horizontal period (for example, the pseudo OB period).

FIG. 1 is a block diagram showing the arrangement of a solid-state image pickup device according to the fourth embodiment. This solid-state imaging device has the same configuration as that of the first embodiment, but the operation of the CCD drive circuit 10A is such that the reset pulse F is generated during the pseudo OB period.
There is a slight difference in that the output is controlled so that R is maintained at a constant level.

FIG. 7A is a signal waveform diagram showing the relationship between the horizontal transfer pulses FH1 and FH2 and the reset pulse FR in the solid-state imaging device of the fourth embodiment.
FIG. 7B is an enlarged view of the portion A of FIG.
5 is a signal waveform diagram showing the timing of FIG.

When the subject image incident through a lens (not shown) is picked up by the CCD 1, the CCD 1 is driven by the horizontal transfer pulses FH1 and FH2 and the reset pulse FR as shown in FIGS. 7 (a) and 7 (b). Outputs a signal having a waveform as shown in FIG. In this figure, the CCD output signal shows the voltage converted by the charge detection unit 77 as an electric signal.

The signal output from the CCD 1 is input to the CDS circuit 2. When the output signal from the CCD 1 in one horizontal period is input to the CDS circuit 2, the clock component included in the signal is removed by the CDS circuit 2 and noise is reduced.

The signal from which the clock component has been removed by the CDS circuit 2 is input to the OB clamp circuit 3 as the first clamp means. The clamp pulse generation circuit 4 is connected to the OB clamp circuit 3, and the clamp pulse CP1 is supplied from the clamp generation circuit 4 in the OB period as shown in FIGS. 7A and 7B. Sometimes, the OB section 7 of the CCD 1 input from the CDS circuit 53
The output signal (OB signal) from 3 is the OB clamp circuit 3
It is clamped by and fixed at the DC level. This produces an OB level signal that is used as an optical black reference. In addition, the effective pixel portion 7 of the CCD 1
The output signal from 2 is output at a level clamped with the signal level of the OB unit 73 as a reference.

The OB level signal output from the OB clamp circuit 3 is input to the video signal processing section 7. In the video signal processing section 7, various signal processing is performed on the output signal from the effective pixel section 72 with reference to the signal level clamped by the OB clamp circuit 3. The video signal processing unit 7 includes, like the conventional solid-state imaging device shown in FIG.
An AGC circuit is provided, and in the AGC circuit, the gain is controlled according to the strength of the signal input from the OB clamp circuit 3.

The output signal from the AGC circuit is input to the correction processing circuit, the gamma-corrected signal is output from the correction processing circuit, and the input signal is clamped to the pedestal level in the pedestal clamp circuit. The output signal from the pedestal clamp circuit is input to the drive circuit, and the drive circuit 59 outputs a video signal suitable for a display device such as a television monitor as a video signal.

The signal from which the clock component has been removed by the CDS circuit 2 is input to the pseudo OB clamp circuit 5 as the second clamp means. 7 (a) and 7
As shown in (b), the reset pulse is held at a constant level for a part of the horizontal period of the CCD 1 (pseudo OB period). The level of the reset pulse at this time is determined by the conversion unit 12
Is reset to a potential equal to that of the reset drain RD, and the voltage transferred from the horizontal transfer portion and leaked out is set to a voltage such that it is completely discharged to the reset drain RD. As a result, all the charges transferred during the pseudo OB portion period are discharged to the reset drain RD. Pseudo OB clamp circuit 5 to CCD drive circuit 1
No control signal for holding the reset pulse FR at a constant level is output to 0A. Reset pulse FR
It is, for example, the CCD drive circuit 10A that controls the CCD 1 to invert the signal level (or control the phase change). As a result, a pseudo signal (pseudo OB signal) corresponding to a level substantially equal to the black level is generated and output from the CCD 1.

A clamp pulse generation circuit 6 is connected to the pseudo OB clamp circuit 5, and the clamp pulse C is supplied from the clamp pulse generation circuit 6 during the pseudo OB period.
When P2 is supplied, the pseudo OB signal is
It is clamped by the clamp circuit 5 and fixed at the DC level. As a result, a signal having a level substantially equal to the original black level is generated.

FIG. 8A is a signal waveform showing the driving timing of the CCD in the solid-state image pickup device of the fourth embodiment, and FIG. 8B is a schematic diagram showing the potential of the horizontal transfer charge of the CCD. . In this figure, the CCD
The mesh part in the output signal indicates the amount of transfer charge.

In the effective video signal period in which the signal from the effective pixel section 72 is output, at the time t1, the horizontal transfer pulse FH1 becomes high level, the horizontal transfer pulse FH2 becomes low level, and the horizontal CCD shift register 76 outputs the output gate OG. The charges are transferred in the direction of. Further, a high level (a level) reset pulse FR is applied to the reset gate 11, and the potential of the conversion unit 12 is reset to the same potential as the reset drain RD.

At time t2, the reset pulse FR becomes low level (b level) and the potential under the reset gate 11 becomes low (shallow), but the potential of the conversion section 12 is at the same level as the potential at time t1. At time t1 and time t2, the potential under the reset gate 11 thus differs due to the induction of the reset pulse FR.

At time t3, the horizontal transfer pulse FH1 goes low and the horizontal transfer pulse FH2 goes high,
The horizontal transfer pulse FH2 is applied to the level where the potential under the transfer electrode to which the horizontal transfer pulse FH1 is applied is low (shallow).
High potential under the transfer electrode (deep)
Transition to level. The lower part of the transfer electrode to which the horizontal transfer pulse FH1 is applied becomes lower (shallow) than the potential under the output gate OG, and the charges are transferred to the conversion section 12. The electric charges thus transferred change the electric potential of the conversion unit 12, and the electric potential change is read out from the CCD 1 as a signal output.

Next, in the pseudo OB period, at time t4, the horizontal transfer pulse FH1 becomes high level and the horizontal transfer pulse FH2 becomes low level, and charges are transferred in the horizontal CCD shift register 76 toward the output gate OG. Further, the reset pulse FR becomes high level (a level), the potential of the reset gate 11 is high (deep), and the potential of the conversion unit 12 is reset to the same potential as the reset drain RD. Therefore, even if an excessive charge is transferred to the conversion unit 12 through the OG gate, all the charges are not discharged to the reset drain RD and converted into a voltage in the conversion unit 12.

On the other hand, in the solid-state image pickup device of the first embodiment shown in FIG. 3, the reset pulse FR is at the low level (b level) and the potential of the reset gate 11 is low (shallow). Since the potential is at the same level as the potential at time t2,
Excessive charge overflows, crosses over the OG gate, and the conversion unit 12
The charge may be converted to a voltage when it flows into the.

At time t5, the reset pulse FR is held at a constant level (high level = a level), the high level (a level) reset pulse FR is applied to the reset gate 11, and the potential of the conversion unit 12 is changed. It is reset to the same potential as the reset drain RD.

On the other hand, in the solid-state imaging device of the first embodiment shown in FIG. 3, when the excessive charge overflows at time t4 and flows over the OG gate into the conversion unit 12, time t5 to time t5. Over a short period of time t6, excessive charges may not be completely discharged to the reset drain RD.

At time t6, the horizontal transfer pulse FH1 goes low and the horizontal transfer pulse FH2 goes high,
The horizontal transfer pulse FH2 is applied to the level where the potential under the transfer electrode to which the horizontal transfer pulse FH1 is applied is low (shallow).
High potential under the transfer electrode (deep)
Transition to level. The lower part of the transfer electrode to which the horizontal transfer pulse FH1 is applied becomes lower (shallow) than the potential under the output gate OG, and charges are transferred to the conversion unit 12, but the potential under the reset gate 11 becomes low (shallow). Therefore, all the charges transferred to the conversion unit 12 are discharged to the reset drain RD. As a result, the excessive light is CCD
Even if the light beam is incident on No. 1, O during the pseudo OB period
Pseudo OB, which is approximately equal to the case where there is no transfer charge to the B section 73
The signal is obtained.

The pseudo OB level signal output from the pseudo OB clamp circuit 5 is input to the detection circuit 8 and detected by the detection circuit 8. Based on the signal output from the detection circuit 8, a signal for controlling the iris and exposure of the CCD 1 from the exposure control unit 9 is supplied to the CCD drive circuit 10A.
Is output to. In the CCD drive circuit 10A, the CCD 1 is driven based on the signal output from the exposure controller 9. The exposure control unit 9 and the CCD drive circuit 10A perform their respective operations with the signal level (pseudo OB level) clamped by the pseudo OB clamp circuit 5 as a reference. The exposure of the CCD 1 is controlled using, for example, an electronic shutter function provided in the CCD 1.

As described above, in the solid-state imaging device of the fourth embodiment, the reset pulse FR can be held at a constant level for a part of the horizontal period (for example, the pseudo OB period), and the charge discharging period can be extended. Even when the excessive light is incident on the CCD 1 and the OB level, which is an optical black reference, fluctuates, proper exposure control can be performed by a pseudo OB level that is substantially equal to the original black level. As a result, good screen display can be performed even when excessive light enters the CCD 1.

Since this pseudo OB level cannot be said to be exactly the same level as the original black level (OB level) due to the influence of induction by the reset pulse FR, it is used as a reference for video signal processing. Not suitable for. Therefore, in the fourth embodiment, only the exposure control is performed based on the pseudo OB level, and the video signal processing is performed based on the OB level, not the pseudo OB level. Since the amount of light incident on the CCD 1 is adjusted by such exposure control based on the pseudo OB level, it is possible to properly perform the video signal processing that is performed based on the OB level. (Fifth Embodiment) In the fifth embodiment, in addition to the above-described fourth embodiment, when the incident light amount is equal to or more than a predetermined amount, the OB in the horizontal period is increased.
This is a case in which the OB clamp circuit 3 is caused to clamp the pseudo black level signal by holding the reset pulse FR at a constant level during the period.

FIG. 5 is a block diagram showing the structure of the solid-state image pickup device according to the fifth embodiment. This solid-state imaging device has the same configuration as that of the third embodiment, but the operation of the reset pulse FR in the OB period is slightly different.

In this solid-state image pickup device, the light amount detecting section 2
In the first embodiment, CC is used according to the control information as in the third embodiment.
The amount of light incident on D1 is detected. Further, in the pulse switching unit 23A, when the amount of incident light detected by the light amount detecting unit 21 is equal to or larger than a predetermined amount, the reset pulse FR is held at a constant level waveform from the pulse waveform within the OB period of the horizontal period of the CCD 1. Can be switched to.

FIG. 9 is a signal waveform diagram showing the drive timing of the solid-state imaging device of this embodiment.

When the amount of incident light detected by the light amount detector 21 is less than the predetermined amount, the OB is the same as in the fourth embodiment.
The reset pulse FR is not switched during the period, and the original black level signal clamped by the clamp pulse CP1 is output from the OB clamp circuit 3. Similar to the fourth embodiment, the video signal processing unit 7 performs various processes with the original OB level signal output from the OB clamp circuit 3 as a reference.

On the other hand, when the amount of incident light detected by the light amount detector 21 is equal to or more than the predetermined amount, the pulse switching unit 2
As shown in FIG. 9, the reset pulse FR is held at a constant level by the 3A during the output period from the OB portion of the CCD 1, and all the charges overflowing to the OB portion 73 are discharged to the reset drain RD. As a result, a pseudo signal (pseudo OB signal) corresponding to a level substantially equal to the black level
Is generated and output from the CCD 1. During the OB period, when the clamp pulse CP1 is supplied from the OB clamp circuit 3, the pseudo OB signal is clamped by the OB clamp circuit 3 and fixed at the DC level.
As a result, a signal of a pseudo OB level that is substantially equal to the original black level (OB level) is generated. In the video signal processing unit 7, various signal processing is performed with the pseudo OB level signal output from the OB clamp circuit 3 as a reference.

In the exposure control section 9, the pseudo OB clamp circuit 5 is supplied when the clamp pulse CP2 is supplied, regardless of the detection result of the light quantity detection section 21, as in the fourth embodiment.
Exposure control is performed on the basis of a pseudo OB level that is substantially clamped at the original black level (OB level), and the CCD1 drive circuit 10A controls the electronic shutter of the CCD1.

As described above, in the solid-state image pickup device of the fifth embodiment, when the amount of incident light is equal to or larger than the predetermined amount, the O in the horizontal period
By holding the reset pulse FR at a constant level in the period B, the OB clamp circuit 3 is caused to clamp the pseudo black level signal. Therefore, depending on the amount of light incident on the CCD 1, an optical black signal is generated when the video signal processing is performed. A standard level of is generated. As a result, appropriate video signal processing can be performed in response to changes in the amount of incident light. In particular, intense light that cannot be avoided even if the maximum exposure control is performed is incident on the CCD 1 and video signal processing can be performed based on the pseudo OB level. It is possible to avoid the worst situation such as blackening and screen failure.

(Sixth Embodiment) In the sixth embodiment, in addition to the first or fourth embodiment, the signal level output from the OB clamp circuit 3 and the pseudo OB clamp circuit are set with reference to the horizontal retrace line level signal. This is a case where the presence or absence of excessive light irradiation to the CCD 1 is detected by detecting the level difference from the signal level output from 5, and the exposure control is performed accordingly.

FIG. 10 is a block diagram showing the structure of the solid-state image pickup device according to the sixth embodiment. In addition, in this figure,
Constituent members having the same functions as those in the first and fourth embodiments are designated by the same reference numerals and the description thereof will be omitted.

In addition to the configuration of the solid-state image pickup device of the first or fourth embodiment shown in FIG. 1, this solid-state image pickup device has a horizontal blanking clamp that clamps a horizontal blanking level signal in a horizontal blanking period irrespective of the amount of incident light. The circuit 24 and the clamp pulse generation circuit 25 are provided.

As shown in FIG. 9, during the horizontal blanking period, the clamp pulse generator circuit 25 outputs the clamp pulse C
When P3 is generated, the horizontal blanking clamp circuit 24 clamps the horizontal blanking level signal that is not affected by the amount of light incident on the CCD 1.

On the other hand, in the horizontal period, the CP1 pulse output from the clamp pulse generating circuit 4 causes the OB
The clamp circuit 3 clamps the OB level signal, and the CP2 pulse output from the clamp pulse generation circuit 6 clamps the pseudo OB level signal in the pseudo OB clamp circuit 6.

Detection circuit 8A as level difference detection means
Is based on the horizontal retrace line level signal output from the horizontal retrace line clamp circuit 24, and serves as the first clamp means.
The level difference between the level of the signal (first signal) output from the B clamp circuit 3 and the level of the signal (second signal) output from the pseudo OB clamp circuit 5 as the second clamp means is detected.

As described above, by detecting the level difference between the level of the first signal output from the OB clamp circuit 3 and the level of the second signal output from the pseudo OB clamp circuit 5, the level difference is determined to be a predetermined value. If the above is the case, a problem has occurred due to irradiation of excessive light, and if the level difference is less than a predetermined value, it can be immediately determined that no problem has occurred, so the processing time can be shortened. (Seventh Embodiment) In the seventh embodiment, in addition to the sixth embodiment, when the level difference is equal to or more than a predetermined amount, it is determined that the excessive light irradiation is performed, and the CCD 1 receives the OB period within the horizontal period. This is a case of switching so that the reset pulse FR is held at a constant level.

FIG. 11 is a block diagram showing the structure of the solid-state image pickup device according to the seventh embodiment. In addition, in this figure,
Constituent members having the same functions as those of the sixth embodiment are designated by the same reference numerals and the description thereof will be omitted.

This solid-state image pickup device is the same as in the second and third embodiments.
In place of the light amount detection unit 21 of the solid-state imaging device of Embodiment 6,
A horizontal blanking clamp circuit 24 and a clamp pulse generation circuit 25 similar to the above are provided.

In this solid-state image pickup device, as in the solid-state image pickup device of the fifth embodiment, when the clamp pulse CP3 is generated from the clamp pulse generation circuit 25 in the horizontal flyback period, the horizontal flyback clamp circuit 24 causes the CCD to move. The horizontal blanking level signal that is not affected by the amount of light incident on is clamped.

On the other hand, in the horizontal period, OB is generated by the CP1 pulse output from the clamp pulse generation circuit 4.
The OB level signal is clamped by the clamp circuit 3, and the pseudo OB clamp circuit 5 clamps the pseudo OB level signal by the CP2 pulse output from the clamp pulse generation circuit 6.

The detection circuit 8A is the horizontal blanking clamp circuit 2
With reference to the horizontal retrace line level signal output from No. 4, the level of the signal (first signal) output from the OB clamp circuit 3 as the first clamp means and the pseudo OB clamp circuit 5 as the second clamp means. The level difference from the level of the signal (second signal) output from is detected.

In the pulse switching section 23B, the detection circuit 8
When it is detected by A that the level difference between the level of the first signal and the level of the second signal is a predetermined amount or more,
Reset pulse F within OB period within horizontal period of CCD1
Reset pulse F so that R is held at a constant level
R is switched.

The detection circuit 8A detects that the level difference between the level of the first signal output from the OB clamp circuit 3 and the level of the second signal output from the pseudo OB clamp circuit 5 is less than a predetermined amount. In this case, as in the case of the fifth embodiment, the reset pulse FR is not switched during the OB period, and the original black level signal clamped by the clamp pulse CP1 is output from the OB clamp circuit 3. Similar to the fourth embodiment, the video signal processing unit 7 performs various kinds of signal processing on the basis of the original OB level signal output from the OB clamp circuit 3.

In the detection circuit 8A, the level difference between the level of the first signal output from the OB clamp circuit 3 and the level of the second signal output from the pseudo OB clamp circuit 5 may be a predetermined amount or more. If detected, the pulse switching unit 23B holds the reset pulse at a constant level during the output period from the OB unit of the CCD 1,
All the charges overflowing into the OB portion 73 are reset drain R
It is discharged to D. As a result, a pseudo signal (pseudo OB signal) corresponding to a level substantially equal to the black level is generated and output from the CCD 1. O during the OB period
When the clamp pulse CP1 is supplied from the B clamp circuit 3, the pseudo OB signal is clamped by the OB clamp circuit 3 and fixed at the DC level. As a result, a signal of a pseudo OB level that is substantially equal to the original black level (OB level) is generated. In the video signal processing unit 7, various signal processing is performed with the pseudo OB level signal output from the OB clamp circuit 3 as a reference.

In the exposure control section 9, the original black clamped by the pseudo OB clamp circuit 5 when the clamp pulse CP2 is supplied is irrespective of the detection result of the detection circuit 8A, similarly to the fourth embodiment. Exposure control is performed with reference to a pseudo OB level that is substantially equal to the level (OB level),
The CCD1 driving circuit 10A controls the electronic shutter of the CCD1.

As described above, in the solid-state imaging device of the seventh embodiment, the level difference between the level of the signal clamped by the OB clamp circuit 3 and the level of the signal clamped by the pseudo OB clamp circuit 5 causes an excessive value. The presence or absence of light irradiation can be promptly determined, and a fixed level that is an optical black reference is generated when performing image signal processing according to this determination, so an appropriate image signal according to the change in the incident light amount is generated. Processing can be performed. In particular, the CCD 1 emits intense light that cannot be avoided even if the maximum exposure control is performed.
Since it is possible to perform the video signal processing on the basis of the pseudo OB level even when the incident light enters, it is possible to avoid the worst situation such as the screen sinking black or the screen collapsing although it cannot be said to be sufficient. (Embodiment 8) In addition to Embodiment 7 described above, the eighth embodiment of the present invention provides a level difference between the level of the signal clamped by the OB clamp circuit 3 and the level of the signal clamped by the pseudo OB clamp circuit 5. In addition, there is a case where an optical black reference level is generated when image signal processing is performed depending on the amount of incident light on the CCD 1 detected by the light amount detector 21.

FIG. 12 is a block diagram showing the structure of the solid-state image pickup device according to the eighth embodiment. In addition, in this figure,
Constituent members having the same functions as those in the above-described Embodiment 7 are designated by the same reference numerals, and the description thereof will be omitted.

This solid-state image pickup device has the same horizontal light-feedback clamp circuit 24, clamp pulse generation circuit 25, and detection circuit as in the above-described seventh embodiment, in addition to the same light amount detecting section 21 as in the solid-state image pickup device of the fifth embodiment. 8A and a pulse switching unit 23B. As a result, the seventh embodiment
Pulse switching can be performed with higher accuracy.

In this solid-state image pickup device, the light amount detection unit 2
1, the amount of light incident on the CCD 1 is detected in accordance with the control information from the exposure controller 9 as in the solid-state imaging device according to the fifth embodiment. The exposure control unit 9 controls, for example, the electronic shutter speed of the CCD 1 so that the output signal level from the CCD 1 becomes constant. Therefore, the light amount detection unit 21 can determine whether or not the incident light amount is equal to or more than a predetermined amount depending on whether or not the electronic shutter speed of the CCD 1 is equal to or more than a predetermined value.

As in the solid-state image pickup device of the seventh embodiment, when the clamp pulse CP3 is generated from the clamp pulse generation circuit 25 in the horizontal blanking period, the horizontal blanking clamp circuit 24 makes the CCD pulse incident on the CCD. The horizontal blanking level signal that is not affected by the amount of light emitted is clamped.

In the horizontal period, the CP1 pulse output from the clamp pulse generation circuit 4 causes the OB
The OB level signal is clamped by the clamp circuit 3, and the pseudo OB clamp circuit 5 clamps the pseudo OB level signal by the CP2 pulse output from the clamp pulse generation circuit 6.

The detection circuit 8A is the horizontal blanking clamp circuit 2
Based on the horizontal retrace line level signal output from 4, the level of the signal (first signal) output from the OB clamp circuit 3 serving as the first clamp means and the pseudo OB clamp circuit serving as the second clamp means. Output signal (second
Signal level).

The detection circuit 8A detects that the level difference between the level of the first signal and the level of the second signal is less than a predetermined amount, and the light amount detecting section 21 determines that the electronic shutter speed is less than the predetermined value. If it is detected that there is a pulse, the pulse switching unit 2
3B, the reset pulse FR is not switched during the OB period, and the OB clamp circuit 3 outputs the clamp pulse C to the reset pulse FR.
The original black level signal clamped by P1 is output. In the video signal processing unit 7, as in the fourth embodiment, the original OB output from the OB clamp circuit 3 is output.
Various signal processes are performed with the level signal as a reference.

On the other hand, the detection circuit 8A detects that the level difference between the level of the first signal and the level of the second signal is equal to or more than a predetermined amount, and the light amount detecting section 21 sets the electronic shutter speed to be equal to or more than a predetermined value. If it is detected that the CCD 1 is detected by the pulse switching unit 23B.
During the output period from the OB unit 73, the reset pulse FR is held at a constant level, and all the charges overflowing into the OB unit 73 are discharged to the reset drain RD. by this,
A pseudo signal (pseudo OB signal) corresponding to a level substantially equal to the black level is generated and output from the CCD 1. OB
During the period, when the clamp pulse CP1 is supplied from the clamp pulse generation circuit 4, the pseudo OB signal is clamped by the OB clamp circuit 3 and fixed at the DC level. As a result, the original black level (O
A signal of pseudo OB level that is substantially equal to (B level) is generated. In the video signal processing unit 7, various signal processing is performed with the pseudo OB level signal output from the OB clamp circuit 3 as a reference.

In the exposure control section 9, regardless of the detection result of the detection circuit 8A, as in the fourth embodiment, the original black clamped by the pseudo OB clamp circuit 5 when the clamp pulse CP2 is supplied. Exposure control is performed with reference to a pseudo OB level that is substantially equal to the level (OB level),
The electronic shutter speed of the CCD 1 is controlled by the CCD 1 drive circuit 10 or 10A.

As described above, in the solid-state imaging device of the eighth embodiment, the level difference between the level of the signal clamped by the OB clamp circuit 3 and the level of the signal clamped by the pseudo OB clamp circuit 5, and Depending on the amount of light incident on the CCD 1 detected by the light amount detector 21, a level that is an optical black reference is generated when image signal processing is performed, so that it is more appropriate in response to changes in the amount of incident light. It is possible to perform various video signal processing. In particular, the intense light CC that cannot be avoided even if the maximum exposure control is performed is CC.
Since the image signal processing can be performed with the light incident on D1 with reference to the pseudo OB level, it is possible to avoid the worst situation such as the screen sinking black or the screen failing, although it cannot be said to be sufficient. (Ninth Embodiment) In the ninth embodiment, in addition to the sixth embodiment, the level difference between the level of the first signal clamped by the OB clamp circuit 3 and the level of the second signal clamped by the pseudo clamp circuit 5. With the detection circuit 8A, it is possible to detect whether or not the CCD 1 is irradiated with intense light of a predetermined level or more, and based on this, as a reference level of an optical black level when performing image signal processing, The signal switching unit 22A causes the OB clamp circuit 3 and the pseudo O
This is a case where each output of the B clamp circuit 5 is switched.

FIG. 13 is a block diagram showing the structure of the solid-state image pickup device according to the ninth embodiment. In addition, in this figure,
Constituent members having the same functions as those of the sixth embodiment are designated by the same reference numerals and the description thereof will be omitted.

This solid-state imaging device is provided with a signal switching section 22A as an output switching means in addition to the configuration of the solid-state imaging device of the sixth embodiment shown in FIG.

In this solid-state imaging device, similarly to the solid-state imaging device of the sixth embodiment, in the horizontal blanking period,
From the clamp pulse generation circuit 25 to the clamp pulse CP3
Is generated by the horizontal blanking clamp circuit 24,
The horizontal retrace line level signal that is not affected by the amount of light incident on the CCD 1 is clamped.

In the horizontal period, the CP1 pulse output from the clamp pulse generation circuit 4 causes the OB
The OB level signal is clamped by the clamp circuit 3, and the pseudo OB clamp circuit 5 clamps the pseudo OB level signal by the CP2 pulse output from the clamp pulse generation circuit 6.

Detection circuit 8A as level difference detection means
Is based on the horizontal retrace line level signal output from the horizontal retrace line clamp circuit 24, and serves as the first clamp means.
The level difference between the level of the signal (first signal) output from the B clamp circuit 3 and the level of the signal (second signal) output from the pseudo OB clamp circuit 5 as the second clamp means is detected.

When the detection circuit 8A detects that the level difference between the level of the first signal and the level of the second signal is less than the predetermined amount, the signal switching section 22A switches the switch to perform the OB clamp. The output from the circuit 3 is input to the video signal processing unit 7. In the video signal processing unit 7, various signal processes are performed with the OB level signal output from the OB clamp circuit 3 as a reference, as in the fourth embodiment.

The pseudo OB level is a pseudo level of the original black level (original OB level), and is not exactly the same level as the original OB level. Therefore, it is desirable to output the video signal with the original OB level as a reference as much as possible. Therefore, if the level difference is less than the predetermined amount,
It is determined that a defect (when the amount of light incident on the CCD 1 is excessive) has not occurred, and image signal processing is performed with the original OB level as a reference.

On the other hand, when the detection circuit 8A detects that the level difference between the level of the first signal and the level of the second signal is a predetermined amount or more, the signal switching section 22A switches the switch, The output from the pseudo OB clamp circuit 5 is input to the video signal processing unit 7. In the video signal processing unit 7, each signal processing is performed with the pseudo OB level output from the pseudo OB clamp circuit 5 as a reference.

As described above, the reason why the pseudo OB level is used is that the level difference between the level of the first signal clamped by the OB clamp circuit 3 and the level of the second signal clamped by the pseudo OB clamp circuit 5 is a predetermined value. This is because if the above is confirmed, the electric charge overflows into the OB portion 73 and the OB level fluctuates. If the level difference is equal to or larger than the predetermined value, the amount of light incident on the CCD 1 is large, and therefore the reset drain cannot fully discharge the charges.

As described above, in the solid-state imaging device of the ninth embodiment, the level difference between the level of the first signal clamped by the OB clamp circuit 3 and the level of the second signal clamped by the pseudo clamp circuit 5 depends on the level difference. It is possible to quickly determine whether or not a defect has occurred, and according to this determination, the level that is the reference of the optical black level when performing video signal processing is switched by the signal switching unit 22A, so the incident light amount It is possible to perform appropriate video signal processing each time according to the change of. As a result, even if intense light is incident on the CCD 1, the image signal processing can be performed using the pseudo OB level as a reference, which is not sufficient, but it is possible to avoid the worst situation such as a screen failure. it can. (Embodiment 10) In Embodiment 10, the above Embodiment 9 is used.
In addition to the above, the output switching unit 22B is set as a reference level of the optical black level when the image signal processing is performed based on the detected irradiation light amount to the CCD 1 by the light amount detection unit 21.
OB clamp circuit 3 and pseudo OB clamp circuit 5
This is the case of switching each output of. The light amount detector 2
The light amount detection by 1 is detected based on the detection information by the detection circuit 8A of the ninth embodiment.

FIG. 14 is a block diagram showing the structure of the solid-state image pickup device according to the tenth embodiment. Note that, in this figure, the constituent members having the same functions as those in the ninth embodiment are designated by the same reference numerals, and the description thereof will be omitted.

This solid-state image pickup device is provided with a light amount detection unit 21 in addition to the configuration of the solid-state image pickup device of the ninth embodiment shown in FIG. 13, and switches the signal switching unit 22B according to the detection output from the light amount detection unit 21. As a result, the OB clamp circuit 3 or the pseudo OB is more accurate than the ninth embodiment.
The clamp circuit 5 and the video signal processing unit 7 can be connected.

In this solid-state image pickup device, the light amount detecting section 2
1, the CCD is controlled according to the control information from the exposure controller 9.
The amount of light incident on 1 is detected. In the exposure control unit 9, CC
CCD so that the output signal level from D1 is constant
The first electronic shutter is drive-controlled (shutter speed). Therefore, the light amount detection unit 21 can determine whether the incident light amount is equal to or more than the predetermined amount, depending on whether the electronic shutter speed of the CCD 1 is equal to or more than the predetermined value.

As in the solid-state image pickup device of the ninth embodiment, when the clamp pulse CP3 is generated from the clamp pulse generation circuit 25 in the horizontal blanking period, the horizontal blanking clamp circuit 24 makes the CCD pulse incident on the CCD. The horizontal retrace line level signal is clamped without being affected by the amount of light emitted.

In the horizontal period, the CP1 pulse output from the clamp pulse generation circuit 4 causes the OB
The OB level signal is clamped by the clamp circuit 3, and the pseudo OB clamp circuit 5 clamps the pseudo OB level signal by the CP2 pulse output from the clamp pulse generation circuit 6.

The detection circuit 8A is the horizontal blanking clamp circuit 2
Based on the horizontal retrace line level signal output from 4, the level of the signal (first signal) output from the OB clamp circuit 3 serving as the first clamp means and the pseudo OB clamp circuit serving as the second clamp means. Output signal (second
Signal level).

The detection circuit 8A detects that the level difference between the level of the first signal and the level of the second signal is less than a predetermined amount, and the light amount detecting section 21 detects the CCD 1
When it is detected that the amount of light incident on the (solid-state image sensor) is less than the predetermined amount, the switch is switched by the signal switching unit 22B, and the output from the OB clamp circuit 3 is input to the video signal processing unit 7. To be done. In the video signal processing unit 7, various signal processes are performed with the OB level signal output from the OB clamp circuit 3 as a reference, as in the fourth embodiment.

On the other hand, the detection circuit 8A detects that the level difference between the level of the first signal and the level of the second signal is equal to or more than a predetermined amount, and the amount of light incident on the solid-state image pickup device is detected by the light amount detector 21. When it is detected that it is less than the predetermined amount, and even when the detection circuit 8A detects that the level difference between the level of the first signal and the level of the second signal is less than the predetermined amount, the light amount detection unit 21 When it is detected that the amount of light incident on the solid-state image sensor is less than the predetermined amount, the signal switching unit 22B switches the switch, and the output from the pseudo OB clamp circuit 5 is input to the video signal processing unit 7. To be done. In the video signal processing unit 7, various signal processing is performed with the pseudo OB level output from the pseudo OB clamp circuit 5 as a reference.

In the exposure control section 9, regardless of the detection result of the light quantity detection section 21, similar to the fourth embodiment, the pseudo OB clamp circuit 5 obtains a pseudo OB substantially equal to the original black level (OB level). Exposure control is performed based on the level, and the CCD shutter 10A drives and controls the electronic shutter of the CCD 1.

As described above, in the solid-state imaging device of the tenth embodiment, the level difference between the level of the signal clamped by the OB clamp circuit 3 and the level of the signal clamped by the pseudo OB clamp circuit 5, and The signal switching unit 22B switches the level serving as an optical black reference when performing image signal processing depending on the amount of light incident on the CCD 1 detected by the light amount detection unit 21, so that it is possible to respond to changes in the incident light amount. Then, appropriate video signal processing can be performed each time. As a result, in particular, even if intense light that cannot be avoided even if the maximum exposure control is performed is incident on the CCD 1, the image signal processing can be performed with the pseudo OB level as a reference, which is sufficient. Although it cannot be said, it is possible to avoid the worst situation such as the screen sinking black or the screen crashing.

Further, with reference to the horizontal retrace line level signal clamped by the OB clamp circuit 24 by the CP3 pulse output from the clamp pulse generation circuit 25, OB
When the black level output input to the video signal processing unit 7 is switched only by the level difference between the first signal level clamped by the clamp circuit 3 and the second signal level clamped by the pseudo OB clamp circuit 5. In the case where the light amount vs. level difference is extremely steep, if the level difference changes in the vicinity of a predetermined amount, the output from the OB clamp circuit 3 is input to the video signal processing unit 7 and the OB clamp level is used as a reference. The screen is changed by repeating the case where the video processing is performed and the case where the output from the pseudo OB clamp circuit 5 is input to the video signal processing unit 7 and the video processing is performed based on the pseudo OB clamp level. Image defects such as flicker may occur.

On the other hand, in the present actual mode 10, the horizontal retrace line signal clamped by the horizontal retrace clamp circuit 24 is used as a reference to simulate the first signal level clamped by the OB clamp circuit 3. Since the switching of the changeover switch 22B is determined based on the level difference between the second signal level clamped by the OB clamp circuit 5 and the incident light amount, it is possible to suppress the occurrence of such an image defect.

As described above, according to the first to tenth embodiments, at least one of the rising and falling timings of the reset pulse FR is changed with respect to the horizontal transfer pulse FH1 during a part of the horizontal period, and here, the resetting is performed. A pseudo OB that inverts the signal waveform of the pulse FR to generate a pseudo OB signal having a level substantially equal to the black level (OB level), and clamps the pseudo OB signal when the clamp pulse is supplied from the clamp pulse generation circuit 6. A clamp circuit 5 is provided. When the excessive light enters the CCD and the transfer charge overflows in the OB portion, the waveform overflow of the reset pulse FR causes the charge overflowing in the OB portion to be discharged to the reset drain RD, and the pseudo OB level substantially equal to the black level. Is generated. By performing the exposure control with the pseudo OB level as a reference, it is possible to display a good screen without being affected by the fluctuation of the OB level as in the conventional case. Therefore, even when excessive light is incident on the CCD, proper exposure control can be easily performed and a good screen display can be obtained.

The solid-state image pickup device of the present invention can be easily incorporated into electronic information equipment such as various cameras, and the effects of the present invention can be obtained. For example, as shown in FIG. 18, the electronic information device 100 allows the user to perform an input operation on the operation unit 104, and based on the operation instruction,
Using the solid-state imaging device 101 of the present invention, a subject image is taken in as external light and an electronic shutter is operated to capture an image.
Various signal processing is performed using the imaged pixel data as image data. An image is displayed on the display unit 102 based on the image data after various signal processing. The image data after various signal processing can be stored in the memory 103, and the image data stored in the memory 103 can be appropriately extracted and displayed on the display unit 102. As described above, when the solid-state imaging device 101 of the present invention is used in the electronic information device 100 and also when excessive light is incident, appropriate exposure control can be easily performed to obtain a good screen display. The effect of the present invention can be obtained.

[0202]

As described in detail above, according to the present invention,
At least one of the rising and falling timings of the reset pulse is changed in a part of the signal read-out period (horizontal period) of the solid-state image sensor, and the pseudo black level corresponding to a level substantially equal to the original black level (OB level). A signal is generated and clamped by the second clamping means. In the exposure controller, the pseudo black level (pseudo OB level) clamped by the second clamp means is used.
The exposure of the solid-state image pickup device is controlled based on the signal of.

Therefore, by the relatively simple structure of adding the second clamp means to the general solid-state image pickup device and the relatively easy control of changing at least one of the rising and falling timings of the reset pulse, Even when excessive light is incident on the solid-state image sensor and the reference black level fluctuates, the exposure is not affected by such fluctuations, and proper exposure is performed with a pseudo black level approximately equal to the original black level as a reference. Control can be performed, and good screen display can be performed.

Further, since the amount of light incident on the solid-state image pickup device is controlled by such exposure control, the original black level (OB level) clamped by the first clamp means is obtained.
The video signal processing, which is performed based on the above, can also be appropriately performed.

Further, according to the present invention, when the light amount detecting means detects that the incident light amount is equal to or more than a predetermined amount,
At least one of the rising and falling timings of the reset pulse is switched by the pulse switching means in another partial period of the horizontal period of the solid-state image pickup device, and the OB portion becomes a level substantially equal to the original black level (OB level). A corresponding signal is output and clamped by the first clamping means. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with reference to the pseudo black level (pseudo OB level) signal clamped by the first clamping means.

Therefore, a signal serving as a reference of the black level is generated when the image signal processing is performed according to the magnitude of the incident light amount, and the appropriate image signal processing can be performed according to the change of the incident light amount. . As a result, in particular, even when intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, it cannot be said to be sufficient, but the pseudo black level is used as a reference. By performing the video signal processing, it is possible to avoid the worst situation in which the screen goes dark and the screen collapses.

Further, according to the present invention, at least one of the rising and falling timings of the reset pulse is changed during a part of the horizontal period of the solid-state image sensor, and the level is substantially equal to the original black level (OB level). Is pseudo-generated and clamped by the second clamp means. The exposure controller controls the exposure of the solid-state image pickup device with reference to the pseudo black level (pseudo OB level) signal clamped by the second clamp means.

Therefore, even if excessive light is incident on the solid-state image sensor and the reference OB level fluctuates, a pseudo black level substantially equal to the original black level is not affected by such fluctuation. Exposure control can be performed as a reference, and good screen display can be performed.

Since the amount of light incident on the solid-state image pickup device is controlled by such exposure control, when the amount of incident light is detected to be less than the predetermined amount by the light amount detecting means, the output switching means is provided. Thus, the output from the first clamp means is input to the video signal processing section. The video signal processing unit can properly perform video signal processing based on the original black level (OB level).

Further, when the light quantity detecting means detects that the quantity of incident light is equal to or larger than the predetermined quantity, the output switching means inputs the output from the second clamp means to the video signal processing section. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with the pseudo black level (pseudo OB level) signal clamped by the second clamping means as a reference.

Therefore, in accordance with the magnitude of the incident light quantity, the signal serving as the reference of the black level is switched by the output switching means when the video signal processing is performed, and the proper video signal processing is performed corresponding to the change of the incident light quantity. It can be carried out. As a result, in particular, even when intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, it cannot be said to be sufficient, but the pseudo black level is used as a reference. By performing the video signal processing, it is possible to avoid the worst situation in which the screen goes dark and the screen collapses.

Further, according to the present invention, the reset pulse is held at a constant level during a part of the signal read-out period (horizontal period) of the solid-state image pickup device, and becomes substantially equal to the original black level (OB level). A corresponding pseudo black level signal is generated and clamped by the second clamp means. The exposure control unit controls the exposure of the solid-state image pickup device based on the signal of the pseudo black level (pseudo OB level) clamped by the second clamp means.

As described above, when changing at least one of the rising and falling timings of the reset pulse in a part of the horizontal period, the charges are transferred from the horizontal transfer unit to the charge detection unit, though for a short time. Then, a time is generated in which the voltage is converted into a charge voltage and output as an output voltage. At this time, when an excessive amount of electric charge is transferred from the horizontal transfer unit to the electric charge detection unit and overflows, the electric charge is converted into a charge voltage. Further, the excessive charge transferred from the horizontal transfer unit to the charge detection unit is discharged to the reset drain, but when the excessive charge is transferred, it is not completely discharged to the reset drain and the charge detection unit does not receive the charge. May remain, and the clamp voltage becomes unstable.

On the other hand, by changing at least one of the rising and falling timings of the reset pulse in a part of the horizontal period, the reset pulse is set to a predetermined constant level, for example, the potential of the charge detection unit is set to the reset drain. The charges are reset to the same potential, and the charges transferred from the horizontal transfer unit and leaked are held at the voltage level where they are completely discharged to the reset drain. As a result, it is possible to eliminate the time for which the charge is output from the charge detection unit, to extend the time for which the charge is discharged to the reset drain, and to completely discharge the charge to the reset drain.

Therefore, due to the relatively simple structure in which the second clamp means is added to the general solid-state image pickup device and the relatively easy control of holding the reset pulse at a constant level, excessive light is transmitted to the solid-state image pickup device. Even if the black level that is the reference and fluctuates, it is possible to perform exposure control with a pseudo black level that is substantially equal to the original black level as a reference without being affected by such fluctuations. The screen can be displayed.

Further, since the amount of light incident on the solid-state image pickup device can be controlled by such exposure control, the original black level (OB level) clamped by the first clamp means is obtained.
The video processing, which is performed based on the above, can also be properly performed.

Further, according to the present invention, when the light amount detecting means detects that the incident light amount is equal to or more than a predetermined amount,
By the pulse switching means, the reset pulse is held at a constant level for a part of the horizontal period of the solid-state image sensor,
A signal corresponding to a level substantially equal to the original black level (OB level) is output from the section and clamped by the first clamp means. In the video signal processing section, the pseudo black level (pseudo O level) clamped by the first clamp means is used.
The video signal output from the effective pixel portion of the solid-state image pickup device is subjected to video signal processing with reference to the (B level) signal.

Therefore, a signal serving as a reference of the black level is generated according to the magnitude of the incident light amount when the video signal processing is performed, and the proper video signal processing can be performed according to the change of the incident light amount. . As a result, in particular, even when intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, it cannot be said to be sufficient, but the pseudo black level is used as a reference. By performing the video signal processing, it is possible to avoid the worst situation in which the screen goes dark and the screen collapses.

According to the present invention, the level difference detecting means detects the level difference between the level of the signal clamped by the first clamping means and the level of the signal clamped by the second clamping means, and the level difference is detected. When it is detected that the difference is a predetermined amount or more, the pulse switching means
The reset pulse is held at a constant level during another partial period of the horizontal period of the solid-state image sensor, and a signal corresponding to a level substantially equal to the original black level (OB level) is output from the OB section and is output by the first clamp means. Clamped. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with reference to the pseudo black level (pseudo OB level) signal clamped by the first clamping means.

To detect the amount of incident light, for example, the second
With the level of the signal clamped by the clamp means as a reference, the output voltage of the solid-state image sensor is detected by, for example, a detection circuit, and based on the output voltage, exposure control is performed when the output voltage is large (control of electronic shutter, etc.). After that, the electronic shutter speed is detected by the light amount detection means,
Although it may be possible to make the determination based on the speed value, it is impossible to instantly determine whether or not the incident light amount is equal to or greater than a predetermined amount because this processing takes time.

On the other hand, by detecting the level difference between the level of the signal clamped by the first clamp means and the level of the signal clamped by the second clamp means by the level difference detection means of the present invention, It is possible to determine the occurrence of a defect in time and to quickly switch the pulse.

Further, by using the level difference detected by the level difference detecting means and the incident light quantity on the solid-state image pickup element detected by the light quantity detecting means as a judgment reference,
It is possible to perform pulse switching with higher accuracy.

Further, according to the present invention, the reset pulse is held at a constant level in a part of the horizontal period of the solid-state image pickup device, and the signal corresponding to the level substantially equal to the original black level (OB level) is pseudo. And is clamped by the second clamp means. The exposure controller controls the exposure of the solid-state image pickup device with reference to the pseudo black level (pseudo OB level) signal clamped by the second clamp means.

Therefore, even if excessive light is incident on the solid-state image sensor and the reference OB level fluctuates, a pseudo black level substantially equal to the original black level is not affected by such fluctuation. Exposure control can be performed as a reference, and good screen display can be performed.

Since the amount of light incident on the solid-state image pickup device is controlled by such exposure control, when the amount of incident light is detected to be less than the predetermined amount by the light amount detecting means, the output switching means Thus, the output from the first clamp means is input to the video signal processing section. The video signal processing unit can properly perform video signal processing based on the original black level (OB level).

When the light quantity detecting means detects that the quantity of incident light is equal to or larger than the predetermined quantity, the output switching means inputs the output from the second clamp means to the video signal processing section. In the video signal processing section, the signal output from the effective pixel section of the solid-state image sensor is processed with the pseudo black level (pseudo OB level) signal clamped by the second clamping means as a reference.

Therefore, according to the magnitude of the incident light quantity, the signal serving as the reference of the black level is switched by the output switching means when the video signal processing is performed, and the proper video signal processing is performed according to the change of the incident light quantity. It can be carried out. As a result, in particular, even when intense light is incident on the solid-state image sensor so that it cannot be avoided even if the maximum exposure control is performed, it cannot be said to be sufficient, but the pseudo black level is used as a reference. By performing the video signal processing, it is possible to avoid the worst situation in which the screen goes dark and the screen collapses.

Further, according to the present invention, the level difference detecting means detects the level difference between the level of the signal clamped by the first clamping means and the level of the signal clamped by the second clamping means. The output signal supplied to the video signal processing unit can be switched by determining the occurrence of a defect in a short time and switching the outputs of the first clamping unit and the second clamping unit. Further, by using the level difference detected by the level difference detection means and the amount of light incident on the solid-state image sensor detected by the light amount detection means as a criterion, each output signal can be switched more accurately. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a solid-state imaging device according to a first embodiment of the present invention.

FIG. 2A is a signal waveform diagram showing a relationship between horizontal transfer pulses FH1 and FH2 and a reset pulse FR in the solid-state imaging device according to the first embodiment of the present invention, and FIG. 2B is a portion A of FIG. 6 is a signal waveform diagram showing the drive timing of the CCD in FIG.

FIG. 3A is a signal waveform diagram showing the driving timing of the CCD in the solid-state imaging device according to the first embodiment of the present invention, and FIG. 3B is a schematic diagram showing the potential of the horizontal transfer charge of the CCD.

FIG. 4 is a block diagram showing a schematic configuration of a solid-state imaging device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a schematic configuration of a solid-state imaging device according to a third embodiment of the present invention.

FIG. 6 is a solid-state imaging device according to a third embodiment of the present invention,
FIG. 6 is a signal waveform diagram showing a driving timing of a CCD.

7A is a signal waveform diagram showing a relationship between horizontal transfer pulses FH1 and FH2 and a reset pulse FR in the solid-state imaging device according to the fourth embodiment of the present invention, and FIG. 7B is a portion A of FIG. 6 is a signal waveform diagram showing the drive timing of the CCD in FIG.

FIG. 8A is a signal waveform diagram showing the driving timing of the CCD in the solid-state imaging device according to the fourth embodiment of the present invention, and FIG. 8B is a schematic diagram showing the potential of the horizontal transfer charge of the CCD.

FIG. 9 is a schematic diagram showing a solid-state image pickup device according to a fifth embodiment of the present invention;
FIG. 6 is a signal waveform diagram showing a CD drive timing.

FIG. 10 is a block diagram showing a schematic configuration of a solid-state imaging device according to a sixth embodiment of the present invention.

FIG. 11 is a block diagram showing a schematic configuration of a solid-state imaging device according to a seventh embodiment of the present invention.

FIG. 12 is a block diagram showing a schematic configuration of a solid-state imaging device according to an eighth embodiment of the present invention.

FIG. 13 is a block diagram showing a schematic configuration of a solid-state imaging device according to a ninth embodiment of the present invention.

FIG. 14 is a block diagram showing a schematic configuration of a solid-state imaging device according to a tenth embodiment of the present invention.

FIG. 15 is a block diagram showing a schematic configuration of a conventional solid-state imaging device.

FIG. 16 is a schematic diagram showing a schematic configuration of one chip of a solid-state image sensor included in the solid-state image pickup device.

FIG. 17A is a signal waveform diagram when the solid-state imaging device is normally operating, and FIG. 17B is a signal waveform diagram when excessive light is incident on the solid-state imaging device.

FIG. 18 is a block diagram showing a basic configuration of an electronic information device when the solid-state imaging device of the present invention is applied to the electronic information device.

[Explanation of symbols]

1, 51 CCD (solid-state image sensor) 2, 53 CDS circuit 3, 54 OB clamp circuit 4, 6, 25 Clamp pulse generation circuit 5 Pseudo OB clamp circuit 7, 55 Video signal processing unit 8, 60 Detection circuit 8A Level difference detection Means 9, 61 Exposure control units 10, 10A, 62 CCD drive circuit (imaging device drive unit) 11 Reset gate 12 Conversion unit 21 Light amount detection unit (light amount detection unit) 22 Output switching units 23, 23A, 23B Pulse switching unit (pulses) Switching means) 24 Horizontal retrace line clamp circuit 52 Lens 56 AGC circuit 57 Correction processing circuit 58 Pedestal clamp circuit 59 Drive circuit 71 Substrate 72 Effective pixel section 73 OB section 73a Light shielding member 74 Photodiode 75 Vertical CCD shift register 76 Horizontal CCD shift register 77 charge detection unit 100 electronic information device Device 101 Solid-state imaging device 102 Display unit 103 Memory 104 Operation unit

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4M118 AA05 AB01 BA13 CA02 DB06                       DB09 DD09 DD12 FA06 GB09                       GB11                 5C022 AA00 AB03 AB06 AB33 AC69                 5C024 CX05 CX06 CX67 GX03 GY01                       GZ36 HX10 HX29 JX44

Claims (16)

[Claims] 1. A solid-state image pickup device detects a video signal photoelectrically converted and a black level signal, and the video signal is signal-processed with the black level signal from the solid-state image pickup device as a reference.
In a solid-state imaging device that resets the detected video signal and the black level signal with a reset pulse, the reset pulse so as to cause the solid-state imaging device to generate a pseudo black level signal that is substantially equal to the black level in a part of the signal reading period. Image pickup device driving means for changing at least one of the rising and falling timings of the image pickup device, and an exposure control portion for controlling the exposure amount of the solid-state image pickup device via the image pickup device driving means on the basis of the pseudo black level signal. Solid-state imaging device having. 2. A first clamp means for clamping the black level signal, a second clamp means for clamping the pseudo black level signal, and one of the first clamp means and the second clamp means. The solid-state imaging device according to claim 1, further comprising: a video signal processing unit that performs video signal processing on the video signal from the solid-state imaging device with reference to the level of the signal. 3. An effective pixel section in which a plurality of photoelectric conversion elements are arranged in a horizontal direction and a vertical direction, subject image light is incident on each photoelectric conversion element to output an electric signal, and a plurality of effective pixel sections are provided around the effective pixel section. Solid-state image pickup device having an optical black portion for outputting an electric signal corresponding to a black level, in which the subject image light is blocked and is not incident on each photoelectric conversion device. First clamp means for clamping a black level signal output from the optical black portion of the image pickup device, and a pseudo black level of a level substantially equal to the black level in the solid state image pickup device during a part of a horizontal period of the solid state image pickup device. An image sensor driving means for changing at least one of the rising and falling timings of the reset pulse so as to generate a signal; Second clamping means for clamping the similar black level signal, and controlling the exposure amount of the solid-state imaging device via the imaging device driving means with reference to the level of the pseudo black level signal clamped by the second clamping means. And an exposure control section for controlling the image signal output from the effective pixel section of the solid-state image sensor with reference to the level of the signal clamped by either the first clamp means or the second clamp means. A solid-state imaging device having a video signal processing unit that performs signal processing. 4. A light amount detection means for detecting whether or not the amount of light incident on the solid-state imaging device is equal to or more than a predetermined amount based on control information from the exposure control unit, and the light amount detection means The solid-state imaging device according to claim 1, wherein at least one of imaging drive control by the imaging element drive unit and exposure amount control by the exposure control unit is performed based on a detection result. 5. The output from the first clamp unit is input to the video signal processing unit when the light amount detection unit detects that the amount of light incident on the solid-state image sensor is less than a predetermined amount. , The first clamp means and the first clamp means such that the output from the second clamp means is input to the video signal processing unit when it is detected that the amount of light incident on the solid-state image sensor is equal to or more than a predetermined amount. The solid-state imaging device according to claim 4, further comprising an output switching unit that switches each output from the two-clamping unit. 6. When at least one of the rising edge and the falling edge of the reset pulse is detected by the light amount detecting means when the amount of light incident on the solid-state imaging device is detected to be a predetermined amount or more, The solid-state imaging device according to claim 4, further comprising pulse switching means for changing the period different from the period. 7. A level difference detecting means for detecting a level difference between the black level signal and the pseudo black level signal,
5. The solid-state image pickup according to claim 1, wherein at least one of image pickup drive control by the image pickup element drive unit and exposure amount control by the exposure control unit is performed based on a detection result by the level difference detection unit. apparatus. 8. The black level signal is input to the video signal processing unit when the level difference detecting means detects that the level difference is less than a predetermined amount, and the level difference is not less than a predetermined amount. The solid-state imaging device according to claim 7, further comprising an output switching unit that switches between the black level signal and the pseudo black level signal so that the pseudo black level signal is input to the video signal processing unit when detected. . 9. The black level signal is input to the video signal processing unit when both detection results of the level difference by the level difference detection unit and the incident light amount by the light amount detection unit are less than a predetermined amount, The black level signal and the pseudo black level signal are switched so that the pseudo black level signal is input to the video signal processing unit when at least one of the detection results is a predetermined amount or more. The solid-state imaging device according to claim 7, further comprising an output switching unit. 10. The level difference detecting means detects at least one of rising and falling timings of the reset pulse different from the partial period when the level difference is detected to be equal to or more than a predetermined amount. The solid-state imaging device according to claim 7, further comprising a pulse switching unit that changes with a period. 11. The partial period when at least one of the detection results of the level difference by the level difference detection unit and the incident light amount by the light amount detection unit is a predetermined amount or more. The solid-state imaging device according to claim 7, further comprising a pulse switching unit that changes at least one of a rising timing and a falling timing of the reset pulse in another period. 12. A change in at least one of rising and falling timings of the reset pulse,
The method according to any one of inverting the signal level of the reset pulse, maintaining a constant level of the reset pulse, and changing the phase of the reset pulse.
11. The solid-state imaging device according to any one of 11. 13. The reset pulse is set to a pulse voltage for resetting the potential of a charge detection unit in the solid-state imaging device to a potential equal to a reset drain in the partial period or another partial period. 13. The solid-state imaging device according to any one of claims 5 to 12. 14. The partial period and the partial period other than the partial period are set to a period in which a signal is output from the optical black portion in the solid-state imaging device. The solid-state imaging device described. 15. The solid-state imaging device according to claim 14, wherein the partial period is set after a partial period different from the partial period. 16. An electronic information device capable of capturing an image using the solid-state imaging device according to claim 1.