Abstract: A dynamic threshold two-level A/D converter, also termed a tracking digitizer circuit. The module circuitry includes a comparator circuit and a tracking low-pass filter circuit. The dynamic thresholding module takes the output signals from a CIS module and develops a tracking (variable) background signal. The tracking background signal is then compared to the output signals from the CIS in a comparator. The comparator outputs a two-level (binary) output digital signal. The circuit is designed to be used in conjunction with a scanning device, particularly a CIS system. The circuit can be used in a wide variety of applications that require pre-processed digitized video signals. The dynamic thresholding module's circuitry can be implemented quite simply. Moreover, the circuit provides a very low cost and a low parts density module that can easily be incorporated with existing CIS modules without substantially increasing the size of the CIS module or the cost to manufacture the unit.

Abstract: A dynamic threshold two-level A/D converter, also termed a tracking digitizer circuit. The module circuitry includes a comparator circuit and a tracking low-pass filter circuit. The dynamic thresholding module takes the output signals from a CIS module and develops a tracking (variable) background signal. The tracking background signal is then compared to the output signals from the CIS in a comparator. The comparator outputs a two-level (binary) output digital signal. The circuit is designed to be used in conjunction with a scanning device, particularly a CIS system. The circuit can be used in a wide variety of applications that require pre-processed digitized video signals. The dynamic thresholding module's circuitry can be implemented quite simply. Moreover, the circuit provides a very low cost and a low parts density module that can easily be incorporated with existing CIS modules without substantially increasing the size of the CIS module or the cost to manufacture the unit.

Abstract: The present invention is to make a switch out of two diodes to read out a third photosensitive transducer which integrates and stores the photon-generated carriers. The switching diodes are arranged so that during their on time, the switching resistance remains linear and constant throughout the photosensitive transducer readout time independent of the number of photon-generated carriers that are stored in the photosensitive transducer. To maintain a low constant on resistance, the two switching diodes in series are pulsed simultaneously with complementary pulses applied to the two terminals of the series diodes to forward bias them during the readout period. The third is a photosensitive transducer, which is connected to the series node of the switching diodes such that the photosensitive diode is always in a reversed bias condition, whether it is in a readout or integration mode.

Abstract: Methods and apparatus for compensating for charge transfer inefficiency in imaging and other variable length charge transfer devices are disclosed. In accordance with the method a recursive filter is used to compensate for the transfer inefficiency of the device with the coefficients of the recursive filter being dependent upon the pixel position and the inefficiency per transfer, or more particularly upon the inefficiency per transfer and the number of transfers required to transfer from the pixel position to the output of the charge transfer device. In addition, a variable gain control is used to restore the amplitude of the output signal dependent upon the pixel position and inefficiency per transfer. Substantial compensation is achieved utilizing recursive filter coefficients linearly increasing with the number of transfers required, with an automatic gain control amplifier also linearly increasing in gain proportional to the number of transfers required to restore signal amplitude.