Victor Company of Japan, Limited

Seigo Kokufukata

Takashi Shinozaki

Shintaro Nakagaki

Tetsuya Sekido

Tetsushi Satoh

A temperature compensation circuit in a pickup tube device comprising a pickup tube, a bias lighting device provided at the front surface of the pickup tube for irradiating a bias light, a circuit for generating a shading compensation signal, and a circuit for supplying a black gate pulse, comprises a temperature compensation signal generating circuit for generating a temperature compensation signal for cancelling variation in a signal current component from the pickup tube due to variation in the bias light obtained from the bias lighting device which is in accordance with temperature variation, a compensation signal obtaining circuit for obtaining a compensation signal by multiplexing the temperature compensation signal generated by the temperature compensation signal generating circuit with the shading compensation signal, and a mixing circuit for mixing the multiplexed compensation signal, the output signal of the pickup tube, and the black gate pulse.

Temperature compensation circuit in a pickup tube device

A color television camera has a camera tube for receiving incident light from an image pickup object. It produces output signals representing an image of the object. The signal level varies in accordance with the incident light quantity assuming a constant target voltage. The system disposes of excessive incident light quantity. A control circuit lowers the voltage impressed on the target of the camera tube and controls the output signal level of the camera tube at a constant value, when the incident light quantity to the camera tube becomes excessive and exceeds a first predetermined light quantity. An indicator indicates when the incident light quantity to the camera tube becomes excessive, exceeding a second predetermined light quantity which is greater than the first predetermined light quantity. The resulting pickup picture deteriorates when the light exceeds a practical allowable limit despite the operation of the control circuit. An iris mechanism is manually operable to reduce the incident light quantity when the indicator indicates that the incident light quantity is in excess of the second predetermined light quantity.

System for controlling excessive incident light in color television

A dark current correction circuit in a two-tube color camera having first and second camera tubes respectively for chrominance signals and luminance signals comprises a circuit for applying to the first camera tube a target voltage in accordance with temperature variation in the image pickup surface thereof, a circuit provided in the picked-up output signal system of the first camera tube and operating to compensate or cancel a dark current component within the picked-up output signal, a circuit for applying to the second camera tube a target voltage in accordance with temperature variation in the image pickup surface thereof, and a circuit for mixing with the picked-up output luminance signal of the second camera tube a horizontal blanking pulse at a level in accordance with the temperature variation in the image pickup surface of that camera tube. The level controlled horizontal blanking pulse, upon being applied to the picked-up output luminance signal, effects correction of a dark current variation component within the luminance signal due to temperature variation in the image pickup surface of the camera tube and for a dark current variation component due to variation of the target voltage.

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Tokyo, Japan

Seigo Kokufukata