JPH02179075A - Charge coupling type solid-state image pickup device - Google Patents

Abstract

PURPOSE:To prevent production of a flicker in an image pickup output by controlling the transfer timing of a charge from a photodetection section to a vertical transfer register so as to reduce the fluctuation of an image pickup output. CONSTITUTION:An image pickup output obtained from an image pickup element 1 is fed to a signal processing circuit 2 and a color video signal SV of the NTSC system is obtained at an output terminal 7. Moreover, the output of the image pickup element 1 is fed to a rectifier circuit 3, in which a high frequency fluctuation component is eliminated and a low frequency component including a DC is extracted. The output signal of the circuit 3 is fed to an A/D converter 4, converted into a digital signal, fed to a microcomputer 5, in which the fluctuation of the image pickup output by periodic lighting of a light source is detected. A timing generating circuit 6 is controlled by the microcomputer 5 and transfer gate pulses P1, P2 at a shutter speed of 1/1000sec are controlled in the timing when the light source is nearly in the same lightness in response to the fluctuation of image pickup output and the image pickup output fluctuation due to periodic fluctuation of the light source is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a camera-integrated videotape recorder (VT
Charge-coupled facepiece imaging device (rC) used in
CD solid-state imaging device).

[Prior Art] A so-called camera-integrated VTR, which is a combination of a video camera and a VTR, has been put into practical use. In this camera-integrated VTR, when obtaining an NTSC color video signal, for example, 60 images are captured and recorded per second using a CCD solid-state image sensor. in this case,
If you wish, you can shoot continuously at an electronic shutter speed of 1760 seconds.
I images and are recorded as video signals of each field.

[Invention tries to solve! ! ! 11. By the way, when the light source that illuminates the subject is one that lights up periodically, such as a fluorescent lamp, when an image is captured using such a camera-integrated VTR, flicker may occur in the image capture output. The images displayed on the TV screen were sometimes very difficult to see.

For example, when the power supply frequency is 50Hz, the brightness of a fluorescent lamp changes continuously with a period of 1/100 seconds, so when images are captured continuously at an electronic shutter speed of 1760 seconds as described above. , there are 17 points with different illuminance.
Images will be taken every 60 seconds. Therefore, flicker with a frequency of 20 Hz occurs in the imaging output.

Incidentally, by making the shutter speed correspond to the period of change in brightness, it is possible to prevent the above-mentioned flicker from occurring. Therefore, conventionally, the shutter speed was
/100 seconds to suppress the occurrence of flicker.

However, recently, a so-called high-speed electronic shutter mode with a storage time of 1/1000 seconds, 1/2000 seconds, etc. has become indispensable as a function of a camera-integrated VTR. In such a mode, the occurrence of flicker cannot be suppressed, and the fluctuation thereof is extremely large, making it impractical for practical use.

Therefore, such a high-speed electronic shutter mode function could not be used when the light source was a fluorescent lamp.

Therefore, it is an object of the present invention to suppress the occurrence of flicker as described above.

[Means for Solving the Problems] The present invention includes a detection means for detecting a TSRS ratio output fluctuation due to periodic lighting of a light source that illuminates a subject, and a TJIT ratio output according to a detection output from this detection means. Control the timing of charge transfer from the light receiving section of the charge-coupled solid-state image sensor to the vertical transfer register so as to reduce fluctuationsa
and control means to control the operation.

[Function] In the above configuration, the light receiving unit l] is arranged so that fluctuations in the imaging output due to periodic lighting of the light source illuminating the subject are reduced.
Since the timing of charge transfer to the vertical transfer register 12 is more controlled, flicker does not occur in the imaging output even when imaging is performed in high-speed shutter mode under a periodically lit light source such as a fluorescent lamp.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

In the figure, reference numeral 1 denotes a CCD solid-state image sensor, which is configured as shown in FIG. 2, for example. That is, 11 is a photodiode that constitutes a light receiving section, 12 is a vertical transfer CCD that constitutes a vertical transfer register, 13 is a horizontal transfer CCD that constitutes a horizontal transfer register, 14 is a drain drain, and 15 is a place where charges of two fields are mixed. This is a charge storage section for a predetermined line to prevent this from occurring.

For example, when the shutter speed is 1/60 second,
A transfer gate pulse is applied between every l/60 vertical blanking ribs to transfer photodiode 1 in a field.
The charges accumulated in 1 should be transferred to vertical transfer CCD I 2. Then, in the next field, the data is sequentially transferred one line at a time to the horizontal transfer CCD 13 via the charge storage section 15, and outputted from the horizontal transfer CCD 13 as an imaging output.

Further, when the shutter speed is 1/I 000 seconds, the first transfer gate pulse P1 is supplied at a predetermined timing in a certain field, and the charge accumulated in the photodiode 11 is transferred to the vertical transfer CCD 12 and the drain 14 It is transferred at high speed in the opposite direction and swept outside. Thereafter, charges are accumulated in the photodiode 11, and from the time when the first transfer gate pulse P1 is supplied, the charge is accumulated.
/1000 seconds later, the second transfer gate pulse P2 is supplied, and the charges accumulated in the photodiode 11 are transferred to the vertical transfer CCD 12. Then, in the next field, 1 is transferred to the horizontal transfer CCD 13 via the charge storage section 15.
The horizontal transfer CCD 13 is sequentially transferred line by line.
It is output as an imaging output.

Note that the transfer lock, transfer gate pulse, etc. necessary for this image sensor 1 are supplied from the timing generation circuit 6.

The imaging output obtained from this image sensor 1 is supplied to a signal processing circuit 2, and an NTSC color video signal Sv is obtained at an output terminal 7 derived from this signal processing circuit 2.

Further, the imaging output obtained from the imaging device 1 is supplied to a rectifier circuit 3, high frequency fluctuation components are removed, and low frequency components including direct current are extracted. this! The output signal of the 1'a circuit 3 is supplied to an A/D converter 4, converted into a digital signal, and then supplied to a microcomputer (hereinafter referred to as "microcomputer") 5. Changes in imaging output due to lighting should be detected.

The above-mentioned timing generation time #J6 is controlled by this microcomputer 5, and is adjusted to 1/100 according to the fluctuation of the ti image output.
Transfer gate pulse P1. at a shutter speed of 0 seconds.
The supply timing of P2 is controlled. In other words, the transfer gate pulses PI and P2 are controlled so as to be supplied at the timing when the light source reaches the brightness level between the paths, thereby reducing fluctuations in the imaging output due to circular fluctuations in the light source.

In the above configuration, the light source illuminating the subject is a fluorescent lamp (
Let us consider a case where the power supply frequency is 50 Hz). In this case, the brightness of the fluorescent lamp is 1/100 as shown in Figure 3A.
Continuously changes every second. Under such a light source, with a shutter speed of 1/1000 second
Image. The supply timing of the transfer gate pulses PI and P2 supplied from the timing generation circuit 6 to the image sensor 1 is as follows.
When it is constant as shown in Figure B, the imaging output from the image sensor 1 changes as the brightness of the fluorescent lamp changes.
As a result, a 20 Hz flicker occurs in the imaging output. On the other hand, the transfer gate pulse PI supplied from the timing generation circuit 6 to the image sensor 1
, P2 is supplied at a timing when the light source becomes brighter than the distance in accordance with fluctuations in the imaging output as in this example, and when the supply timing changes as shown in the figure, The imaging output from the imaging device 1 remains constant as shown in FIG. 5E, regardless of changes in the brightness of the fluorescent lamp.

As described above, according to this example, even if an image is captured at a shutter speed of 1/2000 seconds under a light source that is turned on periodically, such as a fluorescent lamp, flicker will not occur in the image capture output.

Note that the shutter speed of 1/1000 second in the above embodiment is just an example, and it goes without saying that similar effects can be obtained when the shutter speed is set to that song.

[Effects of the Invention] As explained above, according to the present invention, the timing of charge transfer from the light receiving section to the vertical transfer register is controlled so as to reduce fluctuations in the imaging output due to the circular lighting of the light source that illuminates the subject. Therefore, even if you use a high-speed shutter mode under a light source that turns on periodically, such as a fluorescent lamp, there will be no fuzz in the image output. Therefore, it becomes possible to reproduce high-quality images.

・Output terminal ·Photodiode ・Vertical transfer CCD ・Horizontal transfer CCD ・Sweeping drain ・Charge storage section

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of an example of a charge-coupled solid-state image sensing device, and FIG. 3 is an explanatory diagram of the operation of the example shown in FIG.・Charge-coupled solid-state image sensor ・Signal processing circuit ・Rectifier circuit ・A/D converter ・Microcomputer ・Timing generation circuit

Claims (1)

[Claims] (1) A detection means for detecting fluctuations in the imaging output due to periodic lighting of a light source that illuminates the subject, and a charge-coupled solid-state imaging device that detects fluctuations in the imaging output according to the detection output from the detection means. A charge-coupled solid-state imaging device comprising: control means for controlling the timing of charge transfer from a light receiving section of an element to a vertical transfer register.