Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Patent
1996-01-25
1997-12-30
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
250214A, 250214R, 327307, H01J 4014
Patent
active
057033536
ABSTRACT:
Circuitry and method for transferring signals from a photoreceiver array to computational circuitry includes parallel transfer amplifiers that receive periodic offset correction and includes DC removal amplifiers. In a first embodiment, each transfer amplifier has a differential circuit that can be switched from a reset mode to a readout mode. In the readout mode, the voltage state at the output is responsive to first and second inputs, with the second input being connected to a source of a reference voltage. In the reset mode, the inputs are both connected to the reference voltage and the output is temporarily connected to a source of a fixed reset voltage. An offset adjustment signal is generated in response to detection of a voltage difference between the reset voltage and the actual voltage state at the output after the output has been disconnected from the source of the reset voltage. A single offset circuit is used to periodically and sequentially refresh the various transfer amplifiers. In a second embodiment, spatial frequency components at both low and high frequencies are removed from the outputs of the photoreceiver array by DC removal amplifiers. Each DC removal amplifier is assigned to a particular photoelement in the array, but receives outputs from one or more other photoelements in the array. The output of the amplifier is responsive to the differences between the analog signals input to the amplifier.
REFERENCES:
patent: 4488052 (1984-12-01), Zappen et al.
patent: 5149980 (1992-09-01), Ertel et al.
patent: 5321254 (1994-06-01), Yokogawa et al.
C. A. Waton, "Drift Elimination Circuit for Differential Amplifiers", IBM Technical Disclosure Bulletin, Sep. 1969, vol. 12, No. 4, p. 549.
Baumgartner Richard A.
Beard David
Blalock Travis N.
Hornak Thomas
Hewlett--Packard Company
Pyo Kevin
Westin Edward P.
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