A compensating circuit for leakage current comprising part of a signal from a semiconductor image sensor is provided in which a diode is positioned in thermal contact with the image sensor and is reverse biased to produce a leakage current proportional to the image sensor leakage current. Amplifying means is utilized to provide a diode leakage current signal proportional to the leakage current flowing through the diode and equal to the leakage current component of the image sensor signal. The di...

An automatic dark current control for a television (TV) camera or the like comprises the combination of a dark current level sample-hold circuit and a unique low level clipper in parallel with the video output line from the camera vidicon. An electronic switch in the sample-hold circuit is closed once during each field for the duration of one horizontal line sweep of the vidicon electron beam behind the mask on the photosensitive vidicon surface to charge a capacitor to a level corresponding to ...

An offset level of a pixel signal outputted from a linear image sensor having a pixel transfer array disposed along a photodetector is corrected by outputting as empty transfer levels signal levels produced from empty pixel transfer array elements when transfer clock pulses are successively applied to the pixel transfer array after one line of pixel signals is transferred from the photodetector through the pixel transfer array. To determine a correcting quantity of a given pixel of a predetermin...

Elimination of dark fixed pattern noise (DFPN) for tethered CMOS sensor-based digital video cameras is supported by supplying and maintaining a host-based dark image cache. Since the camera is tethered to a host computer system such as a PC, it takes advantage of the storage and processing capabilities of the host to manage the cache. By using a dark image cache for updating of the currently applicable dark image for DFPN cancellation processing, operation of the camera shutter for acquiring dar...

A contact image sensing system that eliminates the use of npn phototransistors. The device comprises a plurality of sensing elements, a like number of dummy sensing elements, control and drive clocks, a digital scanning shift register, and a differential amplifier. The device operates by sequentially reading the voltage output of the sensors, then comparing that output with the output of the dummy sensors so that any noise or offset in the signal can be cancelled by a differential amplifier.

The invention concerns charge coupled devices and the problems of dark current effects. In an arrangement including a charge coupled device utilized as a storage element for data a second charge coupled device is provided. Data is applied to the first device during one half of the storage period, the content of the first device transferred to the second during the second half of the storage period and at the end of the storage period the stored contents of both devices are subtractively combined...

A dark current compensation system for use with a semiconductor imaging device. A p-n junction, thermally connected to the semiconductor imaging device, is forward biased by a temperature variant voltage. The bias voltage is varied in accordance with the temperature of the junction such that the current through the forward biased junction is substantially equal to the reverse saturation current of the junction times a predetermined constant. A dark current compensation signal is derived from the...

There is provided a method of driving an image sensor which can remove FPN resulting from inter-chip variations without requiring any dark correction. A semiconductor photosensor chip has a plurality of sensor modules mounted on a mounting substrate, and a semiconductor device in which at least an N signal input buffer circuit for receiving N signals, an S signal input buffer circuit for receiving S signals, a differential circuit for calculating any difference between the outputs from the N and...

An image processing apparatus for processing an image sensed by an image sensing element such as a CCD sensor includes a dark correction circuit for making dark correction of the image, a defect correction circuit for correcting a defective pixel in the image using other pixels, and a controller for controlling the shares of dark correction by the dark correction circuit and defect correction by the defect correction circuit on the basis of information which pertains to image sensing such as an ...

A number of photodiodes are arranged in line and dark output generating diodes are associated with the respective photodiodes. The light incident side of each dark output generating diode is shielded by a metal film. Two thin-film transistors are respectively connected to the photodiode and the dark output generating diode to transfer charges generated in the respective diodes. A capacitor is connected between the sources of the two thin-film transistors, and stores charges corresponding to the ...