JPS6343953B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic aperture device for a color camera device. Conventional devices of this kind have an electric aperture device, which detects an error signal from the imaging output, and can control the aperture of the electric aperture device to an appropriate aperture state based on this error signal, and can also remove this control. This allows you to change the aperture by turning the aperture ring by hand.

By the way, when changing the aperture manually, if you want to control the automatic black level balance adjustment circuit, it is necessary to manually close the aperture completely or put the filter disk in a light-blocking state in advance. If this is ignored, black level balance adjustment will be impossible.

In view of this, the present invention provides that even when changing the aperture manually, when operating the automatic black level balance adjustment circuit, the incident light is automatically blocked.
The present invention aims to propose an automatic diaphragm device for a color camera device that can reliably adjust the black level balance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. Reference numeral 1 denotes an electric aperture device, which is composed of an aperture 5 provided in a lens system 4 and a motor 6 for driving the aperture 5. 8
is a camera head circuit which obtains, for example, three-color red, green, and blue imaging signals R, G, and B from an image pickup tube, and these signals are supplied to a signal processing circuit 9.
A luminance signal Y and color difference signals RY and BY are obtained from the signal processing circuit 9 and supplied to an encoder 10 of a desired system, for example, an NTSC system. Note that 11 is an output terminal from which a composite color video signal of the NTSC system is obtained.

The signal processing circuit 9 is provided with an automatic black level balance adjustment circuit 3 and an automatic white level balance adjustment circuit 7 in addition to circuits such as a matrix circuit and a γ correction circuit. SW ₂ is a switch (second switch) for operating these adjustment circuits 3 and 7,
It has a movable contact t, a fixed contact W for white level balance adjustment command, and a fixed contact b for black level balance adjustment command. The movable contact t is connected to the power supply +B ₃ (the power supply voltage is V ₃ ), and the adjusting circuits 3 and 7 can be selectively put into operation by switching the movable contact t. Note that n is a neutral contact when neither of the adjustment circuits 3 and 7 is operated.

Reference numeral 2 denotes an automatic aperture control circuit that controls the aperture 5 of the electric aperture device 1 described above to an appropriate aperture state. This includes an error signal generation circuit 12 that detects an error signal from the imaging output, for example, a luminance signal Y, and a potentiometer 14 that generates a voltage according to the error signal and the aperture state of the aperture 5. It is comprised of an arithmetic circuit (comparison circuit) 13 that compares and calculates state detection signals to control the motor 6. The potentiometer 14 has a power supply (the power supply voltage is
V ₄ ) + B ₄ and ground.

During automatic aperture control, one end of the motor 6 is configured to receive a reference voltage of V ₁ /2 from the power supply +B ₂ , and a voltage of 0 to V ₁ is applied to the other end of the motor 6 from the arithmetic circuit 13. It is made so that it can be done.
The reference voltage V ₁ /2 applied to one end of the motor 6 is applied via a switch (first switch) SW ₁ . This switch SW ₁ has a movable contact r connected to one end of the motor 6, a fixed contact a for automatic iris control connected to the power supply +B ₂ , and a fixed contact m for manual iris adjustment.
and has.

In the present invention, a third switch SW 3 is provided which operates in conjunction with the second switch SW ₂ , and this third switch _{SW 3 interrupts} the automatic aperture control circuit 2 caused by the first switch SW ₁ . This is to force the automatic aperture control circuit 2 to operate despite the operation. The third switch SW ₃ is the second switch SW ₂
The configuration is similar to that of the first switch SW1, and the fixed contacts w and b are both connected to the power supply + _B2 whose power supply voltage is V ₁ /2, and the movable contact t is connected to the fixed contact m of the first switch _SW1 . . Also, the fixed contact b of the second switch SW ₂
In particular, it is configured to be also connected to the error signal generation circuit 12.

Next, let us explain the operation of this device. When the electric aperture device 1 is controlled by the automatic aperture control circuit 2 to automatically change the aperture 5, the first switch
The movable contact r of SW ₁ is switched to the fixed contact a side,
A reference voltage of V ₁ /2 is applied to one end of the motor 6 . Then, the rotation of the motor 6 is controlled based on the error signal detected from the luminance signal Y as the imaging output. For example, when the motor 6 rotates forward, the aperture 5
The aperture becomes small and becomes large when rotated in the opposite direction. Further, when a voltage smaller than V ₁ /2 is applied to the other end of the motor 6, the aperture of the diaphragm 5 becomes large, and when a voltage larger than V ₁ /2 is applied, the aperture becomes small. . Also, when aperture 5 is fully open, potentiometer 1
When a voltage of 4 to 0 is generated and it is completely closed,
It is assumed that a voltage of V ₄ is generated and supplied to the respective arithmetic circuits 13. The arithmetic circuit 13 is supplied with a voltage error signal of V ₄ to 0 depending on the magnitude of the luminance signal Y, and when the level of the luminance signal Y is higher than the reference level, the voltage applied to the other end of the motor 6 is set to V _{1 .} When the level of the brightness signal Y is lower than the reference level, the voltage applied to the other end of the motor 6 is set to be smaller than V ₁ /2. Therefore, the arithmetic circuit 13 compares the levels of the error signal from the error signal generating circuit 12 and the detection signal from the potentiometer 14, and rotates the motor 6 in the forward or reverse direction until they match. When the voltage at the other end reaches V ₁ /2, the motor 6 stops its rotation.

Next, when adjusting the aperture 5 manually, the movable contact r of the first switch _SW1 is switched to the fixed contact m. At this time, if the movable contacts t of the second and third switches SW ₂ and SW ₃ are switched to the neutral fixed contact n, automatic aperture control is not performed and the aperture 5 is rotated by the aperture ring (not shown). It can be changed manually depending on the movement.
Also, when the movable contacts t of the second and third switches SW ₂ and SW ₃ are switched to the fixed contacts w or b, the voltage V ₁ /2 from the power supply +B ₂ is applied to the third and first switches SW ₃ and SW ₁ to one end of the motor 6, automatic aperture control is performed in the same manner as described above, and the automatic white level balance adjustment circuit 7 or the automatic black level balance adjustment circuit 3 is brought into operation. In this case, the automatic aperture control circuit 2 operates normally when adjusting the white level balance, but when adjusting the black level balance, the voltage V ₃ from the power supply +B ₃
is supplied to the error signal generation circuit ₁₂ via the second switch SW2, the voltage of the error signal is fixed at _V4 , the motor 6 rotates forward, and the diaphragm 5 is completely closed. In this way, automatic black level balance adjustment is ensured.

According to the present invention described above, even when changing the aperture manually, the aperture is automatically completely closed when the automatic black level balance adjustment circuit is operated, so automatic black level balance adjustment can be reliably performed. can be done.

Further, in the above-described embodiment, even when changing the aperture manually, white level balance adjustment can be performed.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1 is an electric diaphragm device, 2 is an automatic diaphragm control circuit, 3
4 is an automatic black level balance adjustment circuit, 4 is a lens system, 5 is an aperture, 6 is a motor, 7 is an automatic white level balance adjustment circuit, 9 is a signal processing circuit, 12 is an error signal generation circuit, 13 is an arithmetic circuit, and 14 is a Potentiometers SW ₁ to SW ₃ are first to third switches.

Claims (1)

[Claims] 1 an electric aperture device, a detection circuit that detects an error signal from the imaging output, an automatic aperture control circuit that controls the aperture of the electric aperture device to an appropriate aperture state based on the error signal from the detection circuit, and an automatic aperture control circuit that controls the aperture of the electric aperture device to an appropriate aperture state based on the error signal from the detection circuit; In an automatic diaphragm device for a color camera device, the automatic diaphragm device for a color camera device has a first switch that shuts off the operation of an aperture control circuit, an automatic black level balance adjustment circuit, and a second switch that operates the automatic black level balance adjustment circuit. The third switch operates in conjunction with the second switch.
The third switch forcibly operates the automatic diaphragm control circuit despite the cutoff operation by the first switch, and supplies the output of the second switch to the detection circuit. An automatic aperture device for a color camera device, characterized in that the electric aperture device is controlled to a fully closed state by generating a predetermined error signal.