Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
2011-08-02
2011-08-02
Sohn, Seung C (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S2140AG, C250S2140LA, C250S208100
Reexamination Certificate
active
07989753
ABSTRACT:
A photodetector of a wide dynamic range of incident light amount detection and low temperature dependence is provided. A first signal processing unit10m,nincludes an integrating circuit11, a first holding circuit12, a comparing circuit13, a second holding circuit14, and a latching circuit15. The integrating circuit11has a variable capacitor unit that is selectively set to a capacitance value among a plurality of capacitance values, accumulates charges, output from the photodiode, into the variable capacitor unit over an accumulating period that is in accordance with the capacitance value set at the variable capacitor unit, and outputs a voltage V1that is in accordance with the amount of the accumulated charges. The comparing circuit13inputs the voltage V1output from the integrating circuit11, performs a quantitative comparison of the voltage V1with a reference voltage Vref, outputs a compared signal S3expressing the result of comparison, and, when the voltage V1output from the integrating circuit11at the end of an accumulating period is less than the reference voltage Vref, instructs the first holding circuit12to hold the voltage.
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Funakoshi Haruhiro
Mizuno Seiichiro
Taka Tetsuya
Drinker Biddle & Reath LLP
Hamamatsu Photonics K.K.
Sohn Seung C
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