JPH07264493A - Read method for solid-state image pickup element and image pickup device - Google Patents

Abstract

PURPOSE:To provide a read method for the solid-state image pickup element and the image pickup device in which it is prevented that a lateral stripe is generated on a still picture by eliminating smear having been generated in the case of flash synchronous image pickup. CONSTITUTION:A TG 22 stops read pulses SG1, SG2 once just after a flash 1 is flashed. As a result, the charge leaked from a photodetector to a vertical transfer register by the flashing of the flash 1 is shifted by the vertical transfer pulse and aborted and the charge stored in the photodetector at flashing of the flash is read from a CCD 12. Then a S/H circuit 13 applies correlation dual sampling to an image pickup signal from the CCD 12 and a white balance circuit 16 takes white balance of the image pickup signal and a process circuit 17 implements process processing such as gamma correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reading method and an image pickup apparatus for a solid-state image pickup device, and more particularly to a reading method and the like for flash synchronized photographing.

[0002]

2. Description of the Related Art In a conventional image pickup apparatus for photographing a subject and outputting image data of a still image, a subject is flash-synchronized with a video camera including a solid-state image pickup device, and the obtained image pickup signal includes white balance, for example. After performing so-called process processing such as gamma correction, white clipping, and knee processing, the image pickup signal is converted into image data, and this image data is stored in a memory as image data of a still image. Then, the image data of the still image stored in the memory is transferred to, for example, a so-called small computer system interface (hereinafter, referred to as SCSI: Small Computer Sys).
It is called tem Interface. ) To a video printer to print a still image based on this image data (print out).
It is adapted to be transferred to an information processing device such as a personal computer or a workstation via I for use, or to display a still image on a CRT included in the information processing device.

In such a conventional video camera of the image pickup apparatus, a solid-state image pickup element (hereinafter, C) using a charge coupled element as a transfer register for transferring the electric charge accumulated in the light receiving element is used.
Called CD. ) Is used, and a so-called frame reading method is adopted in order to effectively use the number of pixels, that is, the number of light receiving elements.

As shown in FIG. 5, the CCD of the frame reading system reads out the charge accumulated in each of the light receiving elements of the odd field and the even field during one frame (two fields) shifted by one field from each other. S
G1 and SG2 alternately read the data in a so-called vertical transfer register in the field cycle, and then transfer in the vertical direction and in the horizontal transfer register in the horizontal direction to output an image pickup signal.

[0005]

By the way, in the image pickup apparatus using the video camera as described above, so-called smear occurs with respect to a high-luminance input such as a flash light when performing flash synchronized shooting, for example. That is, the light receiving element is saturated and the charge leaks to the vertical transfer register. And
Its charge diminishes over time. As a result, as shown in FIG. 5 described above, the level of the image pickup signal of, for example, an odd field, which is temporally close to the flash emission timing, becomes higher than the level of the image pickup signal of the even field far from the flash emission timing. This phenomenon causes so-called flicker when displayed on a monitor receiver and causes horizontal stripes when printed out, which is a problem.

The present invention has been made in view of the above circumstances, and eliminates smear that occurs in flash synchronized shooting in a conventional image pickup apparatus and can prevent horizontal stripes from occurring in a still image. An object of the present invention is to provide a method for reading out an element and an imaging device.

[0007]

In order to solve the above-mentioned problems, in a method of reading a solid-state image pickup device according to the present invention, a charge-coupled device is used as a transfer register for transferring charges accumulated in a light-receiving device, and an odd number is used. In a method of reading a solid-state image sensor which alternately reads fields and even fields in a field cycle, the vertical transfer register is operated in a state in which the reading of charges from the light receiving element to the vertical transfer register is stopped once during flash emission. .

Further, in the image pickup device according to the present invention, a flash for illuminating an object and a charge-coupled device as a transfer register for transferring the charges accumulated in the light receiving element are used, and an odd field and an even field are alternately arranged in a field cycle. A solid-state image sensor that reads out and outputs an image-capturing signal, an analog / digital conversion unit that converts the image-capture signal from the solid-state image sensor into image data, and image data from the analog / digital conversion unit in synchronization with flash light emission. It is characterized by comprising a storage means for storing and outputting the stored image data, and operating the vertical transfer register in a state in which the reading of charges from the light receiving element to the vertical transfer register is stopped once at the time of flash emission.

[0009]

According to the present invention, the vertical transfer register is operated with the charge read from the light receiving element to the vertical transfer register stopped once when the flash is emitted, and the high brightness flash light leaks from the light receiving element to the vertical transfer register. Discard the generated charge.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a solid-state image pickup device reading method and an image pickup apparatus according to the present invention will be described below with reference to the drawings. An image pickup apparatus to which the present invention is applied, for example, as shown in FIG. 1, a flash 1 for illuminating a subject, a camera head 10 for photographing the subject and outputting an image signal, and an image signal from the camera head 10 are imaged. A digital processor 30 which converts the data into data, stores the data, and outputs the stored image data.

The camera head 10 uses a charge-coupled device as a transfer register for transferring the charges accumulated in the light receiving element, alternately reads out odd fields and even fields in a field cycle, and outputs a so-called image pickup signal. A readout type solid-state imaging device (hereinafter referred to as CCD) is provided, and the vertical transfer register is operated in a state where the reading of charges from the light receiving device to the vertical transfer register is stopped once when the flash 1 emits light. . Also,
The digital processor 30 converts the image signal from the camera head 10 into image data in synchronization with the light emission of the flash 1, stores it as image data of a still image, and outputs the stored image data. .

Specifically, the camera head 10 is, for example,
As shown in FIG. 2, the light enters through the video lens 2.
A color separation prism 11 for separating light into three primary colors, and
Receives each light of the three primary colors from the color separation prism 11.
CCD 12_R, 12_G, 12_BAnd the CCD 12_R
~ 12_BEach output of the so-called correlated double sampling
S / H circuit 13 for outputting the image pickup signals of the three primary colors_R,
Thirteen_G, 13_BAnd the S / H circuit 13_R~ 13_Bfrom
Preamplifier 14 that amplifies each imaging signal _R, 14
_G, 14_BAnd the preamplifier 14_R~ 14_BEach taken from
AGC15 that automatically adjusts the image signal level
_R, 15_G, 15_BAnd the AGC15_R~ 15_Bfrom
White balance for white balance of each image signal
Circuit 16 _R, 16_G, 16_BAnd the white balance times
Road 16_R~ 16_BSo-called process processing for each imaging signal from
Process circuit 17_R, 17_G, 17_BWhen
Equipped with.

The video lens 2 is, for example, a diaphragm,
The color separation prism 11 is composed of a lens capable of remotely controlling zoom, focus and the like, and the color separation prism 11 separates the light incident through the video lens 2 into light of three primary colors.

CCD 12 _{R to} 12 _B (hereinafter collectively referred to as C
It is called CD12. ) Is a frame-reading type solid-state image sensor as described above, receives light of three primary colors, and
The H circuit 13 performs correlated double sampling on the output of the CCD 12 to generate image pickup signals of three primary colors.

The preamplifier 14 amplifies the image pickup signal supplied from the S / H circuit 13 and supplies it to the AGC 15.
The AGC 15 automatically amplifies the image pickup signal so that the image pickup signal has an appropriate level, and supplies the amplified image pickup device to the white balance circuit 16. The white balance circuit 16
The gain is adjusted in advance so that white balance can be obtained, the image pickup signal is amplified by the gain, and the amplified image pickup signal is supplied to the process circuit 17.

The process circuit 17 is composed of, for example, a gamma correction circuit, a white clip circuit, a knee circuit, a black clip circuit, and the like. The image pickup signal supplied from the white balance circuit 16 is subjected to process processing such as gamma correction.
The obtained image signal is supplied to the digital processor 30.

As shown in FIG. 2, the camera head 10 is based on a sync signal generator (hereinafter, referred to as SG) 21 for generating a horizontal sync signal and the like, and a horizontal sync signal and the like from the SG 21. And a timing generation circuit (hereinafter, referred to as TG) for generating the read pulse of the CCD 12 and the like.
22, a driver 23 _H , 23 _V for amplifying a read pulse or the like from the TG 22 and a central processing unit for a camera head (hereinafter, referred to as a camera CPU) for controlling the TG 22T or the like.
Say. ) 24 and.

Then, the SG 21 generates a horizontal synchronizing signal and a vertical synchronizing signal, and supplies these synchronizing signals to the TG 22 and the digital processor 30. On the basis of these synchronization signals, the TG 22 reads pulses SG1 and SG2 for reading out charges accumulated in the light-receiving elements of the odd field and the even field in the period of one frame (two fields) shifted by one field from each other. A vertical transfer pulse for driving the transfer register, a horizontal transfer pulse for driving the horizontal transfer register, etc. are generated, and the drivers 23 _H , 2
The 3 _V drives the CCD 12 with these pulses.
Thus, the charges accumulated in the light receiving element of each field are alternately read from the CCD 12 in the field cycle, and the image signal is supplied from the camera head 10 to the digital processor 30 as described above.

The digital processor 30 is, for example, as shown in FIG.
As shown in FIG. 3, amplifiers 31 _R , 31 _G , 3 for amplifying the image signals of the three primary colors from the camera head 10 are respectively provided.
1 _B and analog / digital converters (hereinafter referred to as A / D converters) 32 _R , which convert the image signals from the amplifiers 31 _{R to} 31 _B into image data of three primary colors, respectively.
2 _G , 32 _B , memories 33 _R , 33 _G , 33 _B for respectively storing the image data from the A / D converters 32 _{R to} 32 _B in synchronization with the light emission of the flash 1, and the memory 33. Memory controller 34 for controlling _{R to} 33 _B
And a small computer system interface (hereinafter referred to as SCSI: Small Comput) that interfaces with an information processing device such as a personal computer.
er System Interface. ) 35 and a CPU 36 for controlling the whole.

The amplifiers 31 _{R to} 31 _B (hereinafter collectively referred to as the amplifier 31) amplify the image signals of the three primary colors supplied from the process circuit 17 of the video camera 10, and the A / D converter 33. Is, for example, using a sampling clock based on the horizontal synchronizing signal supplied from the video camera 10, converts the image signal amplified by the amplifier 31 into image data in which one sample has 8 bits,
This image data is supplied to the memory 33.

Under the control of the CPU 36, when the photographer presses a release button of a remote controller (not shown), the memory controller 34 sends an image sent 3 and 4 fields after the field where the flash 1 emits light. The memory 33 is controlled so that the data is stored.

The memory 33 is composed of a plurality of frame memories, and each time the release button is pressed, the A / D converter 3
The image data supplied from 3 is stored as image data of a still image. Further, the memory controller 34 controls the reading of the image data from each frame memory of the memory 33, and the image data read as needed is SCS.
An information processing device such as a personal computer or a workstation or a video printer (not shown) via I35.
Is supplied to.

Here, the CCD 1 at the time of flash synchronization photography
Reading of No. 2 will be described. As described above, the camera CPU 24 of the camera head 10 normally controls the TG 22 so as to generate the read pulses SG1 and SG2, the vertical transfer pulse, the horizontal transfer pulse, and the like, which alternately read the odd field and the even field in the field cycle. . Thus, the image signal is output from the camera head 10 in the field cycle. That is, a moving image signal is output.

On the other hand, during flash emission, the camera C
For example, as shown in FIG. 4, the PU 24 controls the TG 22 so that the read pulses SG1 and SG2 (shown by broken lines) immediately after the flash 1 emits light is stopped. As a result,
The charges leaked from the light receiving element to the vertical transfer register due to the light emission of the flash 1 are shifted by the vertical transfer pulse and discarded, and then the charges accumulated in the light receiving element at the time of the flash light emission are read out. That is, it is possible to prevent a level difference between the image pickup signal of the odd field and the image pickup signal of the even field due to the high luminance input, that is, the occurrence of smear. In other words, by stopping the read pulses SG1 and SG2 once immediately after the flash emission, for example, so-called flicker is prevented when a still image based on the image data stored in the memory 33 is displayed on the monitor receiver. In addition, it is possible to prevent the occurrence of lateral stripes when printed out. In addition, according to the present invention, it is possible to stop the read pulses SG1 and SG2 once without adding a large scale circuit.
The above effects can be obtained.

[0025]

As is apparent from the above description, according to the present invention, the vertical transfer register is operated in a state in which the reading of charges from the light receiving element to the vertical transfer register is stopped once at the time of flash emission, and the high brightness flash is operated. By discarding the charges leaked from the light receiving element to the vertical transfer register by the light, it is possible to prevent a level difference due to the high-luminance input between the image signal of the odd field and the image signal of the even field, which can be prevented from occurring. It is possible to prevent the occurrence of flicker when displayed on the receiver, and to prevent the occurrence of horizontal stripes when printed out, for example.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image pickup apparatus to which the present invention has been applied.

FIG. 2 is a block diagram showing a specific circuit configuration of a camera head that constitutes the image pickup apparatus.

FIG. 3 is a block diagram showing a specific circuit configuration of a digital processor that constitutes the image pickup apparatus.

FIG. 4 is a time chart for explaining a read operation of a CCD that constitutes the camera head.

FIG. 5 is a time chart for explaining a reading operation of a conventional CCD.

[Explanation of symbols]

1 flash 10 camera head 12 _R , 12 _G , 12 _B CCD 22 TG 24 camera CPU 32 _R , 32 _G , 32 _B A / D converter 33 _R , 33 _G , 33 _B memory 34 memory controller

Claims (2)

[Claims] 1. A method of reading a solid-state imaging device, wherein a charge-coupled device is used as a transfer register for transferring charges accumulated in a light-receiving element, and an odd field and an even field are alternately read in a field cycle. A method of reading a solid-state imaging device, wherein the vertical transfer register is operated in a state in which the reading of charges from the device to the vertical transfer register is stopped once. 2. A flash for illuminating an object and a charge-coupled device as a transfer register for transferring charges accumulated in a light-receiving element are used to alternately read an odd field and an even field in a field cycle to output an image pickup signal. A solid-state image pickup device, an analog / digital conversion means for converting an image pickup signal from the solid-state image pickup device into image data, and image data from the analog / digital conversion means are stored and stored in synchronization with the flash emission. An image pickup device comprising: a storage unit for outputting image data, wherein the vertical transfer register is operated in a state in which reading of charges from the light receiving element to the vertical transfer register is once stopped during flash emission.