JPH06178196A - Ccd camera - Google Patents

Abstract

PURPOSE:To obtain a video signal to conform to a standard by generating adjustment data corresponding to difference between the mean level of the video signal and a reference level, and supplying a timing control signal to determine the accumulation time of a charge to a CCD. CONSTITUTION:In the case that a subject is bright, plus difference is obtained by executing the subtraction of the mean value waveform of the video signal and the reference level by a light quantity detecting part 5. In an adjustment data generating part 6, after adjustment data to control the accumulation time of the charge so as to be reduced in reverse proportion to the plus difference so as to reduce duty is generated, it is supplied to a timing signal generating part 4. The generating part 4 generates a timing pulse to reduce the accumulation time of the charge, and supplies it to the CCD 1. In the case that the subject is dark, the adjustment data to control the accumulation time of the charge so as to be increased in reverse proportion to minus difference is supplied to the generating part 4, and after the generating part 4 generates the timing pulse to increase the accumulation time of the charge and increase a duty ratio, it supplies this timing pulse to the CCD 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CCD (Charge Coupled Device) having an electronic sensitivity adjusting function.
e) The present invention relates to a CCD camera which controls the video signal output level to a predetermined value by changing the charge storage time of the light receiving element of the CCD according to the brightness of the external environment.

[0002]

2. Description of the Related Art Conventionally, in order to cope with a case where the brightness of the outside world changes, a camera supplies a power source and a video signal, and the video signal has a specified value (usually 1.0VP-P).
When the value is larger than the specified value, the diaphragm moves in the closing direction. When the value is smaller than the specified value, the diaphragm automatically opens so that a constant video signal output can be obtained even if the brightness of the subject changes. -There is a CCD camera that uses an iris lens. FIG. 3 is a block diagram of a CCD camera using a conventional auto iris lens. Reference numeral 30 denotes an auto iris lens that supplies an optical image of a subject to the CCD unit 31 and has an automatic light amount adjustment function. Reference numeral 31 denotes an imaging device that converts light into an electric signal, transfers a signal charge, and outputs the electric signal. Is a CCD unit. 32 is the CC
It is a sample and hold unit that processes the signal from the D unit 31 and generates a video signal 37. 33 is a video signal 37
Is input, clamped, gamma-corrected, white-clipped, processed to add a sync signal and the like to generate and output a composite video signal 38. Reference numeral 34 is a timing generator that supplies various timing pulses to the CCD unit 31 and the sample and hold unit 32. Reference numeral 35 denotes a light amount detection unit that stores a reference level, compares the average level of the video signal 37 with the stored level, and outputs a signal according to the level difference. Reference numeral 36 denotes an adjustment data creation unit that outputs a signal for controlling opening / closing of the diaphragm to the auto iris lens 30 based on a signal according to the level difference output from the light amount detection unit 35. When the brightness of the subject becomes bright, the video signal 3
When the average level of 7 increases, and exceeds the level stored in the light amount detection unit 35, for example, the light amount detection unit 35 outputs a positive level difference. The adjustment data creation unit 36
An opening / closing control signal corresponding to the positive level difference is generated and supplied to the auto iris lens 30 so as to reduce the diaphragm of the auto iris lens. The auto-iris lens 30 works to close the diaphragm by the opening / closing control signal. However, the conventional auto iris lens has a problem that it consumes a large amount of power and is expensive because the diaphragm is opened and closed by a motor. Further, since opening and closing of the diaphragm is a mechanical operation, a response speed of opening and closing the diaphragm needs to be about 1 to 2 seconds, and there is a problem in response.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and utilizes a CCD having an electronic sensitivity adjusting function capable of externally controlling the charge accumulation time, and a video output from the CCD. Based on the level difference based on the average level of the signal and the adjustment data corresponding to the level difference, the timing pulse for controlling the charge accumulation time is fed back to the CCD to obtain the video signal that matches the reference level. It is an object to provide a CCD camera.

[0004]

In order to achieve the above object, a lens for forming an optical image of a subject at a predetermined position, and photoelectric conversion of the formed image and changing the charge accumulation time from the outside. And a video signal processing means for generating a video signal from a signal output from the CCD and then generating a composite video signal based on the video signal, and timing after generating a difference between the video signal and a reference level. Sensitivity adjustment data generating means for supplying adjustment data corresponding to the difference to the generating section, and a timing signal for each section and CC based on the adjustment data.
And a timing generator for generating a timing control signal for determining the charge accumulation time of D and supplying the timing signal to the CCD.

[0005]

With the above configuration, the video signal obtained from the optical image of the subject output from the CCD is compared with the reference signal level stored in advance, the difference is obtained, and the sensitivity is adjusted based on the difference. Data is generated, and a timing signal is generated based on the sensitivity adjustment data with a duty ratio changed so as to increase or decrease the charge accumulation time of the CCD in the timing generation unit, and then the generated timing signal is fed back to the CCD. Then, the video signal level is loop-controlled until it matches the reference signal level.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A CCD camera according to the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a CCD according to the present invention.
It is a block diagram of a camera. Reference numeral 1 denotes a CCD capable of adjusting the sensitivity by photoelectrically converting an image of a subject and externally changing the charge accumulation time. 2 is the CC
A sample and hold unit that processes the signal from the D unit 1 and generates a video signal 7. A video signal processing unit 3 receives the video signal 7, clamps it, gamma-corrects it, white-clips it, generates a composite video signal 8 by adding a sync signal, and outputs the composite video signal 8. Reference numeral 4 is a timing signal generator for supplying timing pulses for controlling the charge accumulation time to the CCD unit 1 and for supplying various timing pulses for the sample and hold unit 2. Reference numeral 5 denotes a light amount detection unit that stores a reference level, subtracts the average level of the video signal 7 from the stored reference level, and outputs a signal according to the level difference. 6 generates a timing pulse for controlling the charge accumulation time in the CCD unit 1 based on the signal corresponding to the level difference output from the light amount detection unit 5, so that the adjustment data of the duty ratio of the timing pulse is converted into the timing pulse. It is an adjustment data creation unit that supplies the generation unit. Reference numeral 10 is a lens installed so as to form an optical image of a subject at the position of the CCD.

The operation of the CCD camera according to the present invention will be described. FIG. 2 is a diagram showing an average value waveform of a video signal and a timing pulse waveform for controlling an accumulation time of charges supplied to the CCD unit. The figure (a) shows the case where the subject is bright, and the figure (b) shows the case where the subject is dark. Reference numeral 20 is an average value waveform of the video signal obtained by the light amount detection unit 5 when the subject is bright, and reference numeral 21 is a stored reference level. Reference numeral 23 is a positive difference between the average value waveform 20 of the video signal and the reference level 21. 22 is a light amount detection unit 5
Is a waveform of the average value of the video signal when the subject is dark, and 24 is a negative difference between the average value waveform 22 of the video signal and the reference level 21. 25 is a CCD
Is a one-frame period of photoelectric conversion, and 26 is a charge accumulation time. 27 is the remaining time used for transfer of electric charges. When the subject is bright, a positive difference 23 is obtained by subtracting the average value waveform 20 of the video signal and the reference level 21 in the light amount detection unit 5. The adjustment data creation unit 6 generates adjustment data that is inversely proportional to the plus difference 23 and controls to reduce the charge accumulation time 26 and the duty ratio, and then supplies the adjustment data to the timing signal generation unit 4. The timing signal generator 4 generates a timing pulse that reduces the charge accumulation time 26, and C
Supply to CD1. By repeating the above feedback loop control, the average value waveform of the video signal is made to coincide with the reference level 21 while gradually decreasing. When the subject is dark, the timing signal generator 4 is supplied with adjustment data that is inversely proportional to the minus difference 24 and controls to increase the charge accumulation time 26.
A timing pulse for increasing the charge accumulation time 26 and increasing the duty ratio is generated and then supplied to the CCD 1.
By repeating the above feedback loop control, the average value waveform of the video signal gradually increases and becomes equal to the reference level 21.
Is matched with. The ratio between the charge accumulation time 26 and the remaining time 27 was defined as the duty ratio.

[0008]

As described above, the present invention utilizes a CCD having an electronic sensitivity adjusting function capable of externally controlling the charge accumulation time, and at the same time, the average level and the reference level of the video signal output from the CCD are used. A difference is obtained, adjustment data corresponding to the difference is generated, a timing pulse for controlling the charge accumulation time is generated based on the adjustment data, and the generated timing pulse is fed back to the CCD to set the reference level to the reference level. A CCD camera adapted to obtain a matching video signal is provided. Therefore, it is possible to solve all the problems of high power consumption, high price, and response speed when using the conventional auto iris lens.

[Brief description of drawings]

FIG. 1 is a block diagram of a CCD camera according to the present invention.

FIG. 2 is a diagram showing an average value waveform of a video signal and a timing pulse waveform for controlling an accumulation time of charges supplied to a CCD unit.

FIG. 3 CCD using a conventional auto iris lens
It is a block diagram of a camera.

[Explanation of symbols]

 1 CCD part 2 Sample and hold part 3 Video signal processing part 4 Timing signal generating part 5 Light intensity detecting part 6 Adjustment data creating part 7 Video signal 10 Lens 20 Average value waveform 21 Reference level 22 Average value waveform 23 Positive difference 24 Minus 25 1 frame period 26 Charge accumulation time 27 Remaining time 30 Auto iris lens 31 CCD section 32 Sample and hold section 33 Video signal processing section 34 Timing signal generating section 35 Light intensity detecting section 36 Adjustment data creating section 37 Video signal 38 Composite video signal

Claims (2)

[Claims] 1. A lens for forming an optical image of a subject at a predetermined position, a CCD capable of photoelectrically converting the formed image and externally changing a charge accumulation time, and the CC.
Video signal processing means for generating a video signal from the signal output from D and then generating a composite video signal based on the video signal, and for generating the difference between the video signal and the reference level, and then applying the difference to the timing generation section. Sensitivity adjustment data generating means for supplying the corresponding adjustment data, and timing signals for supplying the respective parts and a timing control signal for determining the charge accumulation time of the CCD based on the adjustment data, and supplying the timing signal to the CCD. A CCD camera comprising a timing generator. 2. The CCD camera according to claim 1, wherein the difference from the reference level is obtained by calculating an average value of the video signal and a reference value stored in advance.