JPS54137913A - Detector for extinction of light source - Google Patents

Detector for extinction of light source

Info

Publication number
JPS54137913A
JPS54137913A JP4542778A JP4542778A JPS54137913A JP S54137913 A JPS54137913 A JP S54137913A JP 4542778 A JP4542778 A JP 4542778A JP 4542778 A JP4542778 A JP 4542778A JP S54137913 A JPS54137913 A JP S54137913A
Authority
JP
Japan
Prior art keywords
light source
extinction
photo
light
series
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP4542778A
Other languages
Japanese (ja)
Inventor
Jiyouichi Fuha
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ricoh Co Ltd
Original Assignee
Ricoh Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to JP4542778A priority Critical patent/JPS54137913A/en
Publication of JPS54137913A publication Critical patent/JPS54137913A/en
Pending legal-status Critical Current

Links

Landscapes

  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Facsimile Scanning Arrangements (AREA)

Abstract

PURPOSE: To detect the extinction of a light source with wide operation tolerance by a simple constitution, by detecting that at least one of transistors goes off judging from the variation in the photo current of the series circuit of transistors.
CONSTITUTION: Between potential +V and the earth, photo transistor Tr14 irradiated with light from light source 7, photo Tr14a irradiated with light from light source 7a, and resistance R1 are connected in series in addition to resistances R5 and R3 connected in series. Now, when light sources 7 and 7a come on to irradiate Trs 14 and 14a, both Trs decrease in internal resistance to flow photo currents. As a result, it is detected by detecting the variation of the photo current of the series circuit that at least one of light sources is extinguished. Consequently, the extinction of a light source with wide operation tolerance can be detected by a simple constitution.
COPYRIGHT: (C)1979,JPO&Japio
JP4542778A 1978-04-19 1978-04-19 Detector for extinction of light source Pending JPS54137913A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4542778A JPS54137913A (en) 1978-04-19 1978-04-19 Detector for extinction of light source

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4542778A JPS54137913A (en) 1978-04-19 1978-04-19 Detector for extinction of light source

Publications (1)

Publication Number Publication Date
JPS54137913A true JPS54137913A (en) 1979-10-26

Family

ID=12718980

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4542778A Pending JPS54137913A (en) 1978-04-19 1978-04-19 Detector for extinction of light source

Country Status (1)

Country Link
JP (1) JPS54137913A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56152099U (en) * 1980-04-12 1981-11-14
JPS60165861A (en) * 1984-02-08 1985-08-29 Tokyo Electric Co Ltd Optical data reader

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56152099U (en) * 1980-04-12 1981-11-14
JPS60165861A (en) * 1984-02-08 1985-08-29 Tokyo Electric Co Ltd Optical data reader
JPH0416986B2 (en) * 1984-02-08 1992-03-25 Tokyo Electric Co Ltd

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