JPH0759049B2 - Video equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The video device of the present invention will be described according to the following items.

A. Industrial field of use B. Outline of the invention C. Prior art D. Problems to be solved by the invention [Fig. 3] E. Means for solving the problems F. Action G. Embodiment [first 1 and 2] a. Image pickup device [Fig. 1] b. Circuit [Fig. 2] H. Effect of the invention (A. Field of industrial application) The present invention relates to a novel image pickup device, particularly an image pickup device. The present invention relates to an image device in which an optical black portion is provided and the level of a signal obtained while scanning the optical black portion is a reference black level.

(B. Outline of the Invention) The present invention provides an image device having a clamp means for providing an optical black portion in an image pickup device and for making a level of a signal obtained when scanning the optical black portion become a reference black level. In order to prevent the level of the signal when scanning the optical black part from fluctuating due to spurious signals or noise and consequently changing the reference of the video signal, in addition to the side of the effective scanning area, In addition, an optical black section is also provided, and a black level fluctuation detection circuit that detects fluctuations in the black level of the video signal is also provided. Normally, the black level is clamped based on the signal sampled during the horizontal sync signal period, When the level fluctuation detection circuit detects the fluctuation of the black level, the black level is detected based on the signal sampled during the vertical sync signal period. Characterized by being adapted to the lamp.

Therefore, according to the present invention, when the video signal greatly changes in level during the horizontal synchronizing signal period to a level different from the level corresponding to black due to light leakage or the like, that is detected by the black level change detection signal, Since the black level is clamped based on the level of the video signal during the vertical synchronizing signal period, the black level fluctuation can be eliminated.

(C. Prior Art) A video device such as a video camera is provided with an optical black portion outside the effective scanning area of the imaging device (for example, vidicon) so that the video signal always has a level corresponding to the brightness of the target. For example, it is possible to determine the pedestal level, the white peak level, and the synchronization level with reference to the level of the video signal when scanning the optical black portion (that is, when scanning the portion where no light enters). It is introduced in Japanese Patent Application Laid-Open No. 49-15111.

There are various conceivable concrete methods for setting the video signal level (black level) when scanning the optical black portion as the video signal reference level.
The most plausible method is to sample the output signal of the amplifier that amplifies the video signal during the sync signal period and feed the sampled signal back to the above amplifier during the hold period to obtain absolute black (black reference).
It is a method of clamping as.

(D. Problems to be Solved by the Invention) [FIG. 3] By the way, the optical black portion described above is provided, and the level of the video signal during the scanning period is clamped as a reference level indicating absolute black. There was also a problem with the method.

This is because, as shown in FIG. 3, when a strong starting subject (for example, the sun, electric light, etc.) d exists at a position relatively close to the optical black portion c in the effective scanning area b of the image pickup apparatus a. Then, the light from the subject d leaks to the periphery and a part of the light also enters under the optical black portion c, and the light is photoelectrically converted. In such a case, the level of the video signal when scanning the optical black portion c deviates from the level corresponding to black, and the deviated level becomes the reference. And if the standards are out of order in this way, the image will be extremely unsightly.

Further, the same phenomenon as described above may occur due to the occurrence of noise.

Note that strong light from the subject may enter the horizontal optical black portion, may enter the vertical optical black portion, or may enter both optical black portions. However, the bad influence of strong light usually extends only to the horizontal optical black portion.

In general, strong light generally enters only a part of the effective scanning area of the screen, and the area of high brightness is much smaller than the area of the screen, so that the range of influence is small. Therefore, when there is high brightness near the horizontal optical black part of the screen or near the vertical optical black part, light leakage to the optical black part occurs, but in the vicinity of the vertical optical black part. Even if a high-brightness part occurs and light leaks in the vertical optical black part, the vertical clamp pulse is
Since the effective scanning area has a wide width corresponding to the width in the horizontal direction, even if the level is momentarily increased due to light leakage, the signal due to the light leakage is integrated and the crank level is hardly affected. Therefore, it is not necessary to consider light leakage to the vertical optical black portion.

To correct. The only problem is how to affect the light leakage to the horizontal optical black part.

The present invention has been made to solve such a problem,
An object of the present invention is to prevent the reference of the video signal from changing even if the level of the signal changes while scanning the horizontal optical black portion.

(E. Means for Solving Problems) In order to solve the above problems, the video device of the present invention amplifies a video signal, and a vertical optical black portion and a vertical optical black portion provided outside the effective scanning area. Amplifier circuit, a black level fluctuation detection circuit for detecting fluctuations in black level, switching means for receiving horizontal gate pulses and vertical gate pulses, a sampling hold circuit for sampling and holding the output of the amplifier circuit, and an input of the amplifier circuit. A clamp means for feeding back and clamping the black level of the amplified signal is provided on the side, and when the switching means normally receives a horizontal gate pulse, when an abnormality occurs and a black level fluctuation detection signal is received from the black level fluctuation detection circuit. A vertical gate pulse is sent to the sampling and holding circuit as a control signal.

(F. Action) Therefore, according to the video device of the present invention, the level of the video signal when scanning the horizontal optical black portion normally provided on the side of the effective scanning area is set as the reference level, When the black level changes, it is possible to clamp it so that the level of the video signal when scanning the vertical optical black portion provided above or below the effective scanning area becomes the reference level. It is possible to prevent the reference of the video signal from being deviated due to the change of the black level.

(G. Embodiment) [FIGS. 1 and 2] Hereinafter, a video device of the present invention will be described in detail according to an embodiment shown in the accompanying drawings.

FIG. 1 and FIG. 2 show an example of the implementation of the video device of the present invention.

(A. Imaging Device) [FIG. 1] FIG. 1 is a front view of the imaging device. In FIG. 1, 1 is an image pickup device, 2 is an effective scanning region of the image pickup device 1, and 3 is a horizontal optical that blocks light incident on one of left and right sides of the effective scanning region 2. Black part, 4
Is a vertical optical black portion that blocks light directed to one of the upper side and the lower side of the effective scanning area 2.

As described above, the image pickup apparatus 1 of the present video apparatus has the effective scanning area 2
An optical black portion 3 for horizontal and an optical black portion 4 for vertical are provided on the outer side of.

(B. Circuit) [FIG. 2] FIG. 2 is a circuit diagram of the video device. In the figure, SW
1 and SW2 are gain up switches. By operating SW1, the gain of the image device can be increased by 9 dB, and by operating SW2, the gain of the image device can be increased by 18 dB.

Reference numeral 5 is an amplifier for amplifying a video signal, 6 is a sampling and holding circuit for sampling and holding the video signal output from the amplifier 5, and 7 is a sampling and holding circuit 6
An amplifier for clamping which appropriately amplifies the signal sampled and held by and feeds it back to the amplifier 5, and 8 is a gate pulse changeover switch, which receives a horizontal gate pulse generated at each horizontal synchronizing signal period at one input terminal and receives the other input. The terminal receives a vertical gate pulse generated every vertical synchronizing signal period, and normally sends a horizontal gate pulse to the sampling hold circuit 6 as a control signal, and receives a black level fluctuation detection signal from the black level fluctuation detection circuit 9. Sometimes the vertical gate pulse is sent to the sampling and holding circuit 6 as a control signal.

The black level fluctuation detecting circuit 9 extracts the level in each horizontal synchronizing signal period of the video signal, that is, the black level, and always checks whether or not it has fluctuated, and when the black level changes, the black level changes. The fluctuation detection signal is sent to the gate pulse changeover switch 8 as a switch control signal. A possible cause of the change in the black level is when the subject l that emits strong light is present near the horizontal optical black portion 3. This is because, as described above, strong light leaks from the subject l under the horizontal optical black portion 3, and an image when scanning the portion of the horizontal optical black portion 3 located on the side of the subject l is scanned. This is because the level of the signal does not become a level corresponding to black because the leaked light is photoelectrically converted.

When the black level changes in this way, a black level fluctuation detection signal is generated from the black level fluctuation detection circuit 9, and the black level fluctuation detection signal is input to the gate pulse changeover switch 8 as a switch control signal. Then, as described above, the gate pulse changeover switch 8 which is normally in the state of transmitting the horizontal gate pulse is in the state of transmitting the vertical gate pulse. As a result, the sampling and holding circuit 6 receives the vertical gate pulse as a control signal, samples the video signal during the period in which the control signal is received, that is, while scanning the optical black portion 4, and clamps it while holding it. It is sent to the amplifier 7. Then, the amplifier 7 returns the held signal to the amplifier 5 to clamp the reference of the video signal.

Therefore, for example, if a subject l that emits strong light leaks light below the horizontal optical black portion 3 and the level of the video signal during scanning of the horizontal optical black portion 3 is deviated, the black level is changed to the deviated level. Is not clamped, but the black level is clamped to the level of the video signal when the vertical optical black portion 4 is being scanned, so that the black reference can be prevented from varying.

If the above-mentioned abnormality occurs while scanning a certain horizontal scanning line, vertical scanning is not started immediately, so a waiting time is set until the start of the next vertical scanning to start vertical scanning. The switch control signal may be input to the gate pulse changeover switch 8 only after that. That is, even if a black level change occurs, the gate pulse changeover switch 8 may be changed over by the switch control signal after waiting for the start of the next vertical scanning without changing the changeover state of the gate pulse changeover switch 8. . This can be easily done by providing an appropriate timing controller.

(H. Effect of the Invention) As is clear from the above description, the video device of the present invention has the horizontal optical black portion formed on the side of the effective scanning area, and on the upper or lower side of the effective scanning area. An image pickup device in which an optical black portion for vertical is formed, an amplifier circuit for amplifying an output signal of the image pickup device, and a black level change detection signal when a black level change of a video signal output from the amplifier circuit is detected. Generates a black level fluctuation detection circuit, receives a horizontal gate pulse generated at each horizontal synchronizing signal period at one input terminal, and receives a vertical gate pulse generated at each vertical synchronizing signal period at the other input terminal Switching means for receiving the output of the fluctuation detection circuit as a switching control signal, and a gate pulse output from the switching means as a control signal for displaying an image from the amplifier circuit. A video device comprising: a sampling and holding circuit for sampling and holding a signal; and a clamping means for clamping the black level of the video signal by feeding back the signal sampled by the sampling and holding circuit to the input side of the amplifying circuit. It is characterized in that the switching means normally maintains a switching state of outputting a horizontal gate pulse, and when it receives a black level fluctuation detection signal from the black level fluctuation detecting circuit, outputs a vertical gate pulse. And

Therefore, according to the video device of the present invention, the level of the video signal when scanning the horizontal optical black portion normally provided on the side of the effective scanning area is set as the reference level, and the fluctuation of the black level is suppressed. When it occurs, it is possible to clamp the video signal level while scanning the vertical optical black part provided above or below the effective scanning area so that it becomes the reference level. It is possible to prevent the reference of the video signal from changing.

[Brief description of drawings]

1 and 2 show an example of an embodiment of the image pickup device of the present invention. FIG. 1 is a front view of the image pickup device, FIG. 2 is a circuit diagram of the image pickup device, and FIG. 3 is a conventional image pickup device. It is a front view. DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Effective scanning area, 3 ... Horizontal optical black part, 4 ... Vertical optical black part, 5 ... Amplifying circuit, 6 ... Sampling hold circuit, 7 ... Clamping means, 8 ... Gate pulse changeover switch, 9 ... Black level fluctuation detection circuit

Claims (1)

[Claims] 1. An image pickup device in which a horizontal optical black portion is formed laterally of an effective scanning region, and a vertical optical black portion is formed above or below the effective scanning region, and an output signal of the image pickup device. , A black level fluctuation detection circuit that generates a black level fluctuation detection signal when a fluctuation in the black level of the video signal output from the above-mentioned amplification circuit is detected, and a horizontal sync signal period at one input terminal Switching means for receiving a horizontal gate pulse generated each time, a vertical gate pulse generated for each vertical synchronizing signal period at the other input terminal, and receiving the output of the black level fluctuation detection circuit as a switching control signal; A sampling and holding circuit that receives the gate pulse output from the controller as a control signal and samples and holds the video signal from the amplifier circuit. And a clamp means for returning the signal sampled by the sampling and holding circuit to the input side of the amplifier circuit to clamp the black level of the video signal, wherein the switching means is normally a horizontal gate pulse. And a switching device for outputting a vertical gate pulse when a black level fluctuation detection signal is received from the black level fluctuation detection circuit.