Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1977-01-03
1978-10-03
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356208, 73293, G01N 2126
Patent
active
041186346
ABSTRACT:
A device for indicating when the level of developer solution in an electrostatic photocopying machine falls to a predetermined level comprises a source of light and a photosensor on which the light source is focused. The photosensor generates a light intensity signal that is related in a known way to the magnitude of light incident on it. Both the light source and photosensor are mounted in a housing, which has a bottom formed to rest firmly on the bottom of the tank that holds the developer solution, and, therefore, are mounted in fixed, spaced relation relative to each other as well as to the housing bottom. A bracket, which includes a spring, supports the housing in the developer solution tank with the housing and tank bottoms in firm interengagement to establish the predetermined developer solution level equal to the distance between the tank bottom and photosensor. A reference signal generator generates a reference signal that is related in an arbitrary way to the light intensity signal generated by the photosensor when the developer solution in the tank is at the predetermined level. Both the photosensor and reference signal generator are connected to a comparator that generates an output signal to indicate if the light intensity signal is greater or less than the reference signal. A visual or aural indicator is responsive to the output signal to indicate that the developer solution has fallen to the predetermined level.
REFERENCES:
patent: 3548657 (1970-12-01), Panerai et al.
patent: 3551670 (1970-12-01), Topol et al.
patent: 3734629 (1973-05-01), Griffiths et al.
patent: 3819278 (1974-06-01), Muller
patent: 3851181 (1974-11-01), Hedle
Carvalko Joseph R.
Tolmie, Jr. Robert J.
Nelms David C.
Pitney-Bowes Inc.
Scribner Albert W.
Soltow, Jr. William D.
Wittstein Martin D.
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