JPH05316415A - Adjustment circuit for ccd camera - Google Patents

Abstract

PURPOSE:To prevent a depth of focus of a picture from being reduced and to avoid occurrence of smear on the picture at the image pickup of an object with a high brightness. CONSTITUTION:Noise is eliminated from an output signal of a CCD 2 at an S/H circuit 3, a detector 5 detects the signal, its output is inputted to an error amplifier 6 via a resistor R2, which calculates a difference between the signal and a setting voltage applied to an inverting terminal and amplifies and outputs the difference. Its output is inputted to a comparator 8, which compares it with a voltage from a level setting circuit 7 and outputs a relevant signal. A signal from the comparator is inputted to a shutter pulse generator 9, from which a required shutter pulse is generated and it is used to control a shutter speed of the CCD 2. The detection output is integrated by a resistor R6 and a capacitor C2, the integrated signal is inputted to a subtractor 10, in which the signal is subtracted from a reference voltage at a noninverting terminal and the result is used to drive a coil L1 of an automatic iris lens 1. A switch circuit 11 is operated with a delay of a time constant comprising a resistor R5 and a capacitor C1 at application of power to delay application of a reference voltage to the subtractor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adjusting circuit of a CCD camera (television camera using a charge coupled device),
The present invention relates to a subject that has a deep depth of focus and does not cause smear in an image when the subject has high brightness.

[0002]

2. Description of the Related Art A CCD camera having an electronic sensitivity adjustment (electronic shutter) function and an auto iris lens diaphragm (automatic diaphragm) function, in which the electronic sensitivity adjustment and the auto iris lens diaphragm operate separately, when the camera is turned on, High shutter speed (for example, 1 / 50,000)
The operation is started in (sec.) And the required speed is gradually reached, but for example, it takes about 3 seconds to reach 1/60 second. In this way, the shutter starts operating at high speed when the power is turned on. For example, when the brightness of the subject is high, balance is performed with the iris of the auto iris lens open in order to bring the video output to the required level, and the shutter operates as it is. Will continue. In such a case, the captured image has a shallow depth of focus, and a large amount of light rays enter the CCD, so smear phenomenon occurs in the image (charges are transferred to adjacent CCDs that do not receive light, and the CCD enters this CCD). The phenomenon of becoming an image as if there was light) occurs.

[0003]

SUMMARY OF THE INVENTION In view of the above, the present invention prioritizes the aperture of the auto iris lens when a high-luminance image is input, and operates the electronic shutter in a sufficiently apertured state. Also, when the power is turned on, the aperture drive of the auto iris lens is prohibited until the required time elapses, the aperture is fully stopped, and the electronic shutter is activated after reaching a low speed. The objective is to keep the required depth of focus according to the above, to obtain a sharp image, and to output an image without smear.

[0004]

In order to solve the above-mentioned problems, the present invention detects the signal from the image pickup device and drives an aperture based on the detection output, and a shutter based on the detection output. In a CCD camera having an electronic sensitivity adjusting circuit for adjusting the speed, a first time constant circuit for delaying the aperture drive of the auto iris lens is provided in the auto iris lens drive circuit, and it operates when the power is turned on to operate the aperture drive of the auto iris lens. An adjustment circuit for a CCD camera is provided which is provided with a second time constant circuit that delays the start for a required time.

[0005]

With the above construction, the CC according to the present invention
In the adjustment circuit of the D camera, the electronic shutter adjustment circuit operates with the auto iris lens fully stopped,
The auto iris lens is driven to stop after reaching the required shutter speed, and when the power is turned on, the auto iris lens is kept in the stopped state until the electronic shutter reaches the required speed. Further, the auto iris lens drive circuit and the electronic shutter drive circuit operate with the same set voltage as a standard.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a CCD camera adjusting circuit according to the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of essential parts of an embodiment of an adjusting circuit of a CCD camera according to the present invention. In the figure, reference numeral 1 denotes an auto iris lens, which opens and closes the diaphragm by a DC voltage applied to the diaphragm driving coil L1. The coil L2 generates a counter electromotive force by the magnetic field generated in the diaphragm drive coil L1 and feeds it back to the drive circuit of the coil L1 via the resistor R7. Reference numeral 2 is an image pickup device such as a CCD. A sample and hold (S / H) circuit 3 removes noise from the signal from the CCD 2 and outputs a signal 4 to a signal processing circuit (not shown). 5 is a detector, S
The signal from the / H circuit 3 is detected. R1 is a resistor for setting the video output level, and outputs a voltage divided and set from the power supply voltage Vc. Reference numeral 6 denotes an error amplifier, which detects the difference when the signal from the detector 5 input to the "+" terminal via the resistor R2 exceeds the reference voltage applied to the "-" terminal via the resistor R3. Calculate and amplify and output.

A level setting circuit 7 outputs a set voltage corresponding to the upper limit of the image level and a set voltage corresponding to the lower limit of the image level for controlling the shutter speed. Reference numeral 8 denotes a comparator which compares the signal from the error amplifier 6 with the voltage from the level setting circuit 8 and outputs a signal when the voltage is higher than the upper limit setting voltage and lower than the lower limit setting voltage, respectively. A shutter pulse generator 9 generates a shutter pulse for controlling the shutter speed of the CCD 2 based on the signal from the comparator 7. Reference numeral 10 is a subtractor (operational amplifier), which inputs the signal from the detector 5 to a resistor.
Integrate with R6 and capacitor C2 and input to the "-" terminal,
The voltage is subtracted from the voltage applied to the "+" terminal, output, and supplied to the diaphragm drive coil L1 of the auto iris lens 1. 11
Is a switch circuit, which turns on when the voltage applied by integrating the resistor R5 and the capacitor C1 from the power source Vc is higher than the required voltage when the power of the camera is turned on, and the "+" terminal of the subtractor 10 is connected to the resistor. Connect to the voltage divider terminal of R1.

Next, the operation of the adjusting circuit of the CCD camera according to the present invention will be described. Light from the subject enters the CCD 2 through the auto iris lens 1, is converted into an electric signal, and is output. This signal is input to the S / H circuit 3, noise is removed, and the signal 4 is output to the video signal processing circuit.
On the other hand, the signal from the S / H circuit 3 is input to the detector 5 and detected. The output of the detector 5 is input to the “+” terminal of the error amplifier 6 via the resistor R2. The reference voltage set by the resistor R1 is applied to the "-" terminal of the error amplifier 6, and the signal from the detector 5 input to the "+" terminal is detected by the voltage of the "-" terminal. In the above cases, the difference between the "-" terminal voltage is calculated, and the amplified value is output at the ratio (R4 / R3) between the resistor R3 and the resistor R4 connected between the "-" terminal and the output terminal. Input to the container 8.

The comparator 8 compares the signal from the error amplifier 6 with the voltage from the level setting circuit 7 and outputs a signal when the voltage is higher than the upper limit voltage of the video level or lower than the lower limit voltage of the video level. .. The output signal of the comparator 8 is input to the shutter pulse generator 9. The shutter pulse generator 9 generates a shutter pulse for controlling the shutter speed at a high speed when the signal level output from the error amplifier 6 is higher than the upper limit, and the signal level output from the error amplifier 6 is lower than the lower limit. When the shutter speed is low, the shutter pulse is generated to control the shutter speed to a low speed and applied to the CCD 2, respectively.

On the other hand, the detection output of the detector 5 is integrated by the resistor R6 and the capacitor C2 and input to the "-" terminal of the subtractor 10. The “+” terminal of the subtractor 10 is connected to the resistor
The reference voltage of the video output level set by R1 is applied, and the voltage input to the "-" terminal is calculated (subtracted) from the voltage of the "+" terminal and output. This output is applied to the drive coil L1 of the auto iris lens 1 and the auto iris lens 1 is activated when the drive voltage increases (the brightness of the subject decreases).
The diaphragm is opened, and the diaphragm is closed by decreasing the drive voltage (increasing the brightness of the subject).

The shutter speed control timing of the shutter pulse generator 9 is delayed by a time required for signal processing with respect to a change in the detection output of the detector 5. Therefore, the signal input to the subtractor 10 is delayed so that the aperture of the auto iris lens 1 is not opened and driven first. That is, when the signal from the detector 5 input to the "-" terminal of the subtractor 10 is delayed by a required time in consideration of the shutter speed control timing, the time when the integrating circuit is formed by the resistor R6 and the capacitor C2. Set a constant. Thereby, for example, when the output of the detector 5 decreases (the brightness of the subject decreases), the opening drive of the aperture of the auto iris lens 1 is delayed by the time corresponding to the time constant, and the shutter speed is in the low speed direction during this time. Controlled so that the depth of focus of the image remains unchanged. As described above, since the error amplifier 6 and the subtractor 10 operate on the basis of the same set voltage, only the shutter speed changes and the aperture of the auto iris lens does not change when the brightness of the subject changes (or the shutter speed does not change). Does not change, and only the aperture changes).

Further, since the voltage integrated by the resistor R5 and the capacitor C1 is applied from the power source Vc to the drive terminal of the switch circuit 11, the ON operation of the switch circuit 11 is made to be the time constant of the integrator circuit when the power is turned on. There will be a corresponding delay in time. As a result, the application of the reference voltage to the “+” terminal of the subtractor 10 for the time constant is delayed, the opening drive of the diaphragm of the auto iris lens 1 is delayed, and the shutter operates at a speed corresponding to the brightness of the subject during this time. Reach (slow). Therefore, for example, when the power of the camera is turned on, when the brightness of the subject is high, the shutter speed operates at a high speed, and the aperture operates in a relatively open state (the depth of focus is shallow, and smear occurs in the image). It can be avoided.

[0013]

As described above, C according to the present invention
According to the adjustment circuit of the CD camera, the aperture of the auto iris lens operates prior to the speed control operation of the electronic shutter, and when the power is turned on, the aperture of the auto iris lens is driven after the electronic shutter reaches the required low speed operation. As a result, the diaphragm is opened to obtain an image with a deep depth of focus when a high-luminance subject is imaged, and smear of the image is reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential part of an embodiment of an adjustment circuit of a CCD camera according to the present invention.

[Explanation of symbols]

 1 Auto Iris Lens 2 Image Sensor (CCD) 3 Sample Hold (S / H) Circuit 5 Detector 6 Error Amplifier 7 Level Setting Circuit 8 Comparator 9 Shutter Pulse Generator 10 Subtractor (Operational Amplifier) 11 Switch Circuit L1 Aperture Driving Coil R1 Video output level setting resistor R5 resistor R6 resistor C1 capacitor C2 capacitor

Claims (2)

[Claims] 1. A CCD camera having an auto-iris lens drive circuit for detecting a signal from an image pickup device and driving a diaphragm based on a detection output, and an electronic sensitivity adjustment circuit for adjusting a shutter speed based on the detection output.
The auto iris lens drive circuit is provided with a first time constant circuit for delaying the aperture drive of the auto iris lens, and a second time constant circuit is provided which is activated when the power is turned on and delays the start of the aperture drive of the auto iris lens by a required time. Adjustment circuit for CCD camera. 2. A CCD camera having an auto-iris lens drive circuit for detecting a signal from an image pickup device and driving a diaphragm based on a detection output, and an electronic sensitivity adjustment circuit for adjusting a shutter speed based on the detection output.
The auto iris lens drive circuit is provided with a first time constant circuit for delaying the aperture drive of the auto iris lens, and a second time constant circuit is provided which is activated when the power is turned on and delays the start of the aperture drive of the auto iris lens by a required time. An adjustment circuit for a CCD camera in which the reference voltage for operation of the auto iris lens drive circuit and the reference voltage for operation of the electronic sensitivity adjustment circuit are set to the same voltage.