Title:
CONTAMINATION DETECTOR FOR TRANSLUCENT PANEL
Document Type and Number:
Japanese Patent JP3447324
Kind Code:
B2
Abstract:
PURPOSE: To allow detection only of the extent of contamination of a translucent panel positively regardless of the temporary fluctuation in the environmental brightness by smoothing the outputs of reflected light and external transmission light, picking up the peak values thereof and then determining the difference therebetween.
CONSTITUTION: A photodiode 20a feeds a current having magnitude corresponding to the environmental brightness constantly to a detection resistor 20b thus producing a DC voltage Q onto which a pulse voltage P is superposed to produce a signal A. The signal A is smoothed by a smoothing circuit 21 to produce a voltage B having waveform approximately to that of the voltage Q. The signal A is also fed to a peak hold circuit 22 which produces a voltage C. In other words, when a light transmitting/receiving window glass is not contaminated, the voltage C having waveform approximate to that of the voltage Q is outputted and the difference D between the signals B, C, determined by a subtraction circuit 23, does not exceed the reference voltage of a comparator 24 and thereby a contamination alarm is not produced. Upon contamination of the window glass, output voltage C from the circuit 22 varies significantly to increase the difference thus producing 24 a signal E.
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Inventors:
Jun Nishino
Hiroshi Takeda
Rugo Shigeru
Hidefumi Ito
Takashi Yoshimura
Hiroshi Takeda
Rugo Shigeru
Hidefumi Ito
Takashi Yoshimura
Application Number:
JP14803993A
Publication Date:
September 16, 2003
Filing Date:
June 18, 1993
Export Citation:
Assignee:
Calsonic Kansei Corporation
Photoelectric Manufacturing Co., Ltd.
Photoelectric Manufacturing Co., Ltd.
International Classes:
G01J1/02; G01N21/88; G01N21/93; G01N21/94; G01N21/958; G01V8/12; (IPC1-7): G01N21/94; G01J1/02; G01N21/958; G01V8/12
Domestic Patent References:
| JP5719625A | ||||
| JP5223937A | ||||
| JP5302887A | ||||
| JP62135950U |
Attorney, Agent or Firm:
Hiroaki Tazawa (1 person outside)