JP2970496B2 - Solid-state imaging camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging camera having a charge transfer element for transferring a charge generated in a light receiving portion such as a photodiode to an output terminal, and particularly when a high-luminance light is incident. The present invention relates to a solid-state imaging camera that suppresses deterioration of image quality due to a blooming phenomenon.

[0002]

2. Description of the Related Art A two-dimensional image pickup device has light receiving elements such as photodiodes arranged in an array, and generates electric charges according to the intensity of light received by each light receiving element. Then, the charges generated by these light receiving elements are transferred to a predetermined signal output terminal by means for transferring the charges such as a charge-coupled device (hereinafter, referred to as a CCD). A solid-state imaging camera is a camera that captures an image of a subject using such an imaging device.

In a high-brightness portion where the intensity of light input to the solid-state imaging camera is high, the amount of charges generated by the photodiode becomes extremely large, and excessive charges leak into the surrounding pixel area. For this reason, a so-called blooming phenomenon such as bleeding or sagging occurs in the output image. Since the blooming phenomenon significantly deteriorates the quality of an image, various proposals have been made to suppress the occurrence of this phenomenon even when a high-luminance subject is photographed.

Japanese Patent Application Laid-Open No. 4-273777 discloses that, when the level of a signal output from a solid-state image sensor is equal to or higher than a reference value, the amount of charge generated in a photodiode is adjusted by adjusting the aperture and shutter speed. There is disclosed a solid-state imaging camera for reducing the number of images. By reducing the intensity of the light incident by the aperture and increasing the shutter speed,
The light receiving time at the photodiode is shortened. As a result, the amount of charges generated in the photodiode is reduced, thereby suppressing the occurrence of the blooming phenomenon.

Japanese Patent Application Laid-Open No. Hei 5-316439 discloses a solid-state imaging camera in which blooming caused by overflow of charges in a CCD portion for transferring charges generated by a photodiode is reduced. CCD
The device is configured to sequentially shift the position of a depletion layer generated by applying a voltage to a semiconductor layer, so that charges collected in the depletion layer are transferred to an output terminal. The depletion layer that stores charges is called a potential well. If the charge generated by the photodiode is large and overflows from the potential well of the CCD, the blooming phenomenon also occurs. So CC
The presence or absence of the blooming phenomenon is detected based on the output signal from D. When the blooming phenomenon is detected, the voltage applied to the CCD unit is increased to deepen the potential well, thereby preventing the charge from overflowing the well. I have.

[0006]

Problems to be Solved by the Invention
If the aperture is adjusted by the auto iris function or the shutter speed is increased in order to obtain an appropriate exposure as shown in Japanese Patent Application Laid-Open No. 7, the blooming phenomenon can be suppressed for a high-luminance input of a certain level or less. Also, by adjusting the amplification gain of the output signal of the CCD by the AGC function, it is possible to reduce the occurrence of the blooming phenomenon due to the saturation in the circuit at the subsequent stage. However, there is a problem that a blooming phenomenon occurs when very high-intensity light exceeding the range that can be adjusted by these is input.

Further, as in the prior art disclosed in Japanese Patent Application Laid-Open No. 5-316439, by adjusting the depth of the well of the CCD potential, the blooming phenomenon caused by the overflow of the electric charges in this portion is prevented. Can be suppressed. However, if the charge generated in the photodiode leaks into a peripheral image area before being transferred to the CCD, a blooming phenomenon occurs. Further, when the potential well is deep, it is difficult to transfer the electric charge, and a clear image cannot be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solid-state imaging camera capable of suppressing the occurrence of a blooming phenomenon even when high-luminance light exceeding a range that can be adjusted by an aperture or a shutter speed is input.

[0009]

[0010]

[0011]

According to the first aspect of the present invention, there are provided: (a) a plurality of light receiving units for generating electric charges according to the intensity of light to be received, and a predetermined signal output from the electric charges generated by these light receiving units. and charge transfer means for sequentially transferring toward the end, the charge generated in the light receiving portion and the solid-state imaging device having a charge transfer means for transferring to the charge transfer means, (b) the light receiving portion of the solid-state imaging device An aperture that reduces the amount of incident light;
(C) a shutter speed setting means for setting a shutter speed of the solid-state imaging means; and (d) a solid-state imaging means for setting a suppression voltage for determining an amount of electric charge which escapes to a part other than the electric charge transferring means when electric charges are transferred from the light receiving section to the electric charge transferring means. (E) blooming detecting means for detecting the occurrence of a blooming phenomenon caused by input of high-brightness light to the solid-state imaging means based on an output signal output from a signal output end; ( F ) When the blooming detection means detects the occurrence of the blooming phenomenon, the amount of generated charge is reduced by changing the amount of reduction of the light amount by the aperture and the shutter speed within their adjustment ranges to reduce the amount of charge generated in the light receiving unit. And ( g ) the blooming detection even when the aperture and shutter speed are adjusted within their adjustment ranges by the generated charge amount suppressing means. The solid-state imaging camera further includes a suppression voltage changing unit that changes the suppression voltage output from the suppression voltage supply unit when the occurrence of the blooming phenomenon is detected by the output unit and increases the amount of charge that escapes to a portion other than the charge transfer unit. I have.

That is, according to the first aspect of the invention, when the occurrence of the blooming phenomenon is detected, the occurrence of the blooming phenomenon is suppressed by first changing the aperture and the shutter speed. Then, when the blooming phenomenon cannot be suppressed even by adjusting the aperture and the shutter speed, the suppression voltage is changed to increase the amount of charge released to other than the charge transfer means.

According to the second aspect of the present invention, the blooming detecting means detects whether or not a blooming phenomenon has occurred in each unit area obtained by dividing the imaging area of the solid-state imaging means into a plurality of areas, and detects the blooming phenomenon in at least one unit area. Then, a detection signal indicating the occurrence of the blooming phenomenon is output.

That is, according to the second aspect of the present invention, when the occurrence of the blooming phenomenon is detected in at least one of the unit areas obtained by dividing the imaging area into a plurality of parts, the suppression voltage is changed or the aperture is adjusted. Like that. Even if high-brightness light is incident on only a part of the imaging region, the blooming phenomenon can be appropriately detected and its occurrence can be suppressed.

[0015]

FIG. 1 shows an outline of the configuration of a solid-state imaging camera according to an embodiment of the present invention. Light from a subject is collected by a lens 11 onto a CCD sensor 12 having a two-dimensional imaging area. A CCD sensor 12 is provided between the lens 11 and the CCD sensor 12.
An aperture 13 is provided for reducing the amount of light incident on the aperture. The aperture control circuit 14 is a circuit that supplies a signal specifying the size of the aperture of the aperture 13 to the aperture 13. C
The CD sensor drive circuit 15 is a circuit that generates various drive signals for operating the CCD sensor 12. The shutter speed setting circuit 16 is a circuit for setting the length of a period for converting received light into electric charges. The shutter speed is arbitrarily set by the photographer according to the subject to be photographed.

The standard output setting circuit 17 is a CCD sensor 1 corresponding to the exposure set by the photographer as the optimum exposure.
2 is a circuit for providing a standard output value 19 of the value of the output signal 18. The comparison circuit 21 outputs the value of the standard output 19 output from the standard output setting circuit 17 and the output signal 1 of the CCD sensor 12.
8 is a circuit for comparing with the value of 8. The comparison result 22 of the comparison circuit 21 is input to the aperture control circuit 14. The aperture control circuit 14 sequentially changes the aperture diameter of the aperture 13 based on the comparison result 22 from the comparison circuit 21 so that the value of the output signal 18 of the CCD sensor 12 matches the standard output value 19. That is, the amount of attenuation of the light amount by the aperture 13 is changed in accordance with the incident light amount that changes according to the subject to be photographed,
An appropriate exposure is maintained by giving priority to the shutter speed.

The comparison result 22 obtained by the comparison circuit 21 is input to the blooming detection circuit 21. Also, CC
The output signal 18 of the D sensor 12 is input to the blooming detection circuit 21 via the comparison circuit 21. The blooming detection circuit 21 is a circuit that checks whether or not a blooming phenomenon has occurred based on the output signal 18 of the CCD sensor 12.

When an appropriate exposure can be obtained by adjusting the aperture diameter of the aperture 13 and the shutter speed, the CCD sensor 1
The value of the output signal 18 of 2 gradually approaches and matches the standard output value 19. However, when an appropriate exposure cannot be obtained within the adjustment range of the aperture 13 or the like, the output signal 1
A difference equal to or greater than a certain value appears continuously between the value of 8 and the standard output value 19. When such a state is reached, the blooming detection circuit 22 starts detecting whether or not a blooming phenomenon has occurred. When the blooming phenomenon is detected, the blooming detection circuit 22 outputs a detection signal indicating the fact and a blooming amount signal 23 indicating the degree of overexposure.

These signals are input to a blooming suppression substrate voltage supply circuit 24. The blooming suppression board voltage supply circuit 24 is a circuit that outputs a blooming suppression board voltage signal 25 to be supplied to the CCD sensor 12. C
The CD sensor 12 outputs a blooming suppression substrate voltage signal 25.
According to the voltage value, a part of the charge generated in the photodiode of the CCD sensor 12 is released. The blooming suppression board voltage supply circuit 24 changes the voltage value of the blooming suppression board voltage signal 25 according to the value of the blooming amount signal 23. The output signal 18 of the CCD sensor 12 is input to a video signal processing circuit 26 via a comparison circuit 21. The video signal processing circuit 26 is a circuit that converts the output signal 18 from the CCD sensor 12 into a video signal of a predetermined format.

FIG. 2 shows an outline of the internal structure of the CCD sensor. The CCD sensor has a large number of light receiving sections 31 (photodiodes) arranged in an array. A charge transfer section 32 for transferring charges generated in the light receiving section is provided corresponding to each column of the light receiving section. The charge transfer unit 32 is a shift register that transfers charges.
The charge generated in the light receiving unit is transferred to the charge transfer unit 32 through the charge transfer unit 33. The output of the charge transfer unit 32 is input to a shift register 34 that transfers charges in the horizontal direction. The shift register 34 sequentially shifts the charge input from the charge transfer unit 32 toward the output terminal 35. The serial signal output from the output terminal 35 is a CCD signal.
It becomes an output signal of the sensor 12.

The charge transfer section 33, so as to make a depletion layer as a path for transferring charges generated by the light receiving portion to the charge transfer part
It has become.

FIG. 3 shows an outline of the circuit configuration of the blooming detection circuit shown in FIG. The blooming detection circuit divides the imaging area of the CCD sensor 12 into a plurality of small areas and checks whether a blooming phenomenon has occurred in each of the small areas. When the occurrence of the blooming phenomenon is detected in at least one small area, a detection signal notifying the blooming suppression substrate voltage supply circuit 24 of the occurrence is output.

The blooming detection circuit is a CCD sensor 1
2 and an average output calculation circuit 41 for each area, which calculates the average value of the output signals for each small area, and a vertical column of the imaging area, that is, the output signal value for each charge transfer unit 32 shown in FIG. Vertical average output calculation circuit 42 for obtaining an average value
It has. These include the comparison result 2 of the comparison circuit 21.
2 and an output signal 18 of the CCD sensor 12 are input. An output of the average output calculation circuit 41 for each area;
The output of the vertical average output calculation circuit 42 is input to a difference calculation circuit 43 that calculates these differences for each small area.

The output of the difference calculation circuit 43 and the threshold value 4
4 is input to the comparison circuit 45. Comparison circuit 45
Is a detection signal 4 indicating the occurrence of the blooming phenomenon when the output value of the difference calculation circuit 43 is larger than the threshold value 44.
6 is output. The output of the difference calculation circuit 43 is input to the blooming suppression substrate voltage supply circuit 24 as a blooming amount signal 23 indicating the degree of blooming.

FIG. 4 shows an example in which the imaging area is divided into small areas. Here, the imaging area is indicated by an arrow 51.
The vertical direction indicated by the arrow 52 is divided into 70, and the horizontal direction is indicated by "10", and the vertical direction indicated by the arrow 52 is divided into "7".
The blooming phenomenon may appear in the entire imaging region, but most of it appears in a part of the imaging region. For example,
In some cases, high-brightness light is incident only on the hatched small area 53. Therefore, the blooming detection circuit 22 detects the presence or absence of the blooming phenomenon for each small area, and when finding any area where the blooming phenomenon occurs,
A detection signal is output.

Returning to FIG. 3, the description will be continued. Comparison circuit 21
When it is detected that an appropriate exposure cannot be obtained within the adjustment range such as the aperture, based on the comparison result from, the average output calculation circuit 41 for each area, based on the output signal 18 of the CCD sensor 12,
The average value is obtained for each small area shown in FIG. on the other hand,
The vertical average output calculation circuit 42 calculates the average value of the output signal of the CCD sensor 12 for each column in the vertical direction of the imaging area. The difference detection circuit 43 calculates a difference between the average value of each small area and the average value of a column crossing the small area.

As shown in FIG. 4, when only a part of the high-luminance area exists, the average value of the small area becomes large. However, the average value of the column in the vertical direction crossing the small area is not so large. The comparison circuit 44 checks whether or not these differences are equal to or larger than the threshold value. When the difference is equal to or larger than the threshold value, it is determined that the blooming phenomenon has occurred in the small area. When there are a plurality of small areas having a difference equal to or larger than the threshold value, the largest difference value is output as the blooming difference signal 23.

Blooming suppression substrate voltage supply circuit 24
When the blooming phenomenon is detected, the blooming suppression substrate voltage 25 is set according to the value of the blooming signal 23.
Increase. As a result, the amount of charge absorbed by the charge transfer unit increases, and the amount of charge transferred from the light receiving unit to the charge transfer unit decreases. As a result, excessive charge is not input to the charge transfer unit, and the occurrence of the blooming phenomenon can be suppressed.

As described above, since the excess charge is released before being input to the charge transfer section, the blooming phenomenon can be prevented without increasing the depth of the potential well in the charge transfer section. Can be suppressed. Thereby, a clear image can be obtained. Also, only when high-luminance light exceeding a range that can be adjusted by an aperture or the like is incident, the blooming substrate suppression voltage is increased to remove excess charges. Therefore, within a range that can be adjusted by an aperture or the like, a sufficient dynamic range of the CCD sensor can be secured, and a decrease in contrast can be prevented.

[0030]

As described above, according to the first aspect of the present invention, when the occurrence of the blooming phenomenon is detected,
First, change the aperture and shutter speed to suppress the occurrence,
These can suppress the occurrence of blooming phenomenon
If not, change the suppression voltage to escape
Increase the amount of electric charge. This makes it possible to adjust the aperture
Blooming even when high-intensity light exceeding the adjustment range is incident
The occurrence of the phenomenon can be suppressed. Also, depending on the aperture etc.
Within the adjustable range, the dynamics of the solid-state imaging
Ensuring sufficient cleansing and preventing reduction in contrast
Can be

[0031]

[0032] According to the second aspect of the invention, even if a high luminance of the light is incident only on a part of the imaging region, it can be suppressed properly detected and that generates a blooming phenomenon.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an outline of a configuration of a solid-state imaging camera according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an outline of an internal structure of a CCD sensor.

FIG. 3 is a block diagram illustrating an outline of a circuit configuration of a blooming detection circuit illustrated in FIG. 1;

FIG. 4 is an explanatory diagram illustrating an example in which an imaging region is divided into small regions.

[Explanation of symbols]

 Reference Signs List 12 CCD sensor 13 Aperture 14 Aperture control circuit 15 CCD drive circuit 16 Shutter speed setting circuit 17 Standard output setting circuit 21, 45 Comparison circuit 22 Blooming detection circuit 23 Blooming suppression substrate voltage supply circuit 31 Light receiving unit 32, 34 Charge transfer unit 33 Charge Transfer unit 41 Average output calculation circuit for each area 42 Vertical average output calculation circuit 43 Difference calculation circuit

Claims (2)

(57) [Claims] A plurality of light receiving sections for generating electric charges in accordance with the intensity of light to be received, charge transfer means for sequentially transferring the charges generated in the light receiving sections to a predetermined signal output end, A solid-state imaging device having charge transfer means for transferring the charge generated in the light-receiving portion to the charge transfer device, and reducing the amount of light incident on the light-receiving portion of the solid-state imaging device
Aperture to be set and a shutter speed for setting a shutter speed of the solid-state imaging means.
Degree setting means, suppression voltage supply means for applying to the solid-state imaging means a suppression voltage for determining the amount of charge released to other than the charge transfer means when transferring the charge from the light receiving section to the charge transfer means, wherein the blooming detecting means for detecting the occurrence of the blooming phenomenon caused by light intensity is inputted based on an output signal outputted from said signal output terminal, when the occurrence of the blooming phenomenon is detected by the blooming detecting means The amount of light reduction due to the aperture and
Change the shutter speed and shutter speed within their
Charge amount suppressing means for reducing the amount of charge generated in the unit
And the aperture and the shutter by the generated charge amount suppressing means.
Even if the motor speed is adjusted within these adjustment ranges.
The occurrence of the blooming phenomenon is detected by the
And a suppression voltage changing means for changing the suppression voltage output from the suppression voltage supply means to increase the amount of electric charge leaked to a part other than the charge transfer means. 2. The solid-state imaging device according to claim 1, wherein
Blue for each unit area obtained by dividing the imaging area of the unit into multiple
Detecting whether or not the occurrence of the
Blooming occurs when a blooming phenomenon is detected in the
Outputs a detection signal indicating the occurrence of the switching phenomenon
The solid-state imaging camera according to claim 1.