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US 4,128,760 AGranted
Ambient light compensating circuit
AssigneeNCR Corporation
InventorJames R. Del Signore, II
Life of this patent
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AssigneeNCR Corporation
InventorJames R. Del Signore, II
Estimating the term…
An automatic ambient light compensating circuit for use in conjunction with a light sensing device to render the light sensing device insensitive to variations in ambient light conditions and which is particularly adapted for use with reflective sensor systems. An optical sensor, including a source of light and a first photodetector, is disposed to detect the presence of an object in proximity thereto. The optical sensor provides an output signal which is a function of the amount of light received by the first photodetector and includes light from the source of light and ambient light. The output signal of the optical sensor is provided as an input to a signal level detection means. A second photodetector responsive only to ambient light is operatively connected in parallel with the output of the optical sensor to the level detection means to compensate the output signal of the optical sensor for ambient light conditions.
An ambient light compensating circuit, comprising:
In a light sensitive control circuit having a first photodetector means providing an output responsive in part to a source of light and in part to ambient light, signal level means connected with said output for detecting that portion thereof responsive to said source of light, the improvement comprising:
In an apparatus for detecting the presence of a record member, said apparatus utilizing a light source and first sensor means for reflective sensing of said record member, and signal level means connected with said first sensor means, and wherein said first sensor means has an output on which is provided a signal responsive in part to light from said light source and in part to ambient light, said signal level means detecting the light source portion of said signal, the improvement comprising:
Dependencies are inferred from the claim text.