JPS54158116A - Automatic contrast adjusting device - Google Patents

Automatic contrast adjusting device

Info

Publication number
JPS54158116A
JPS54158116A JP6694378A JP6694378A JPS54158116A JP S54158116 A JPS54158116 A JP S54158116A JP 6694378 A JP6694378 A JP 6694378A JP 6694378 A JP6694378 A JP 6694378A JP S54158116 A JPS54158116 A JP S54158116A
Authority
JP
Japan
Prior art keywords
level
original
detection circuit
voltage
minimum
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.)
Granted
Application number
JP6694378A
Other languages
Japanese (ja)
Other versions
JPS6126744B2 (en
Inventor
Hiroshi Mitsuda
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.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
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 Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP6694378A priority Critical patent/JPS54158116A/en
Publication of JPS54158116A publication Critical patent/JPS54158116A/en
Publication of JPS6126744B2 publication Critical patent/JPS6126744B2/ja
Granted legal-status Critical Current

Links

Landscapes

  • Image Input (AREA)
  • Facsimile Image Signal Circuits (AREA)

Abstract

PURPOSE: To secure the setting to the optimum threshold level even for the original featuring a smaller width than the effective reading length by providing the time constant circuit which gives reply only to the low-region component to the detection circuit of the white maximum level and then detecting the minimum level.
CONSTITUTION: Photoelectric conversion signal v1 is applied to maximum level detection circuit 8, and the minimum level of output waveform v2 is made to coincide substantially with the background density level of the original through setting of discharge time constant R3C1. Thus, the minimum voltage of v2 is detected at detection circuit 9 to obtain voltage v3 corresponding to the background density level of the original. And furthermore, maximum level detection circuit 10 is provided in order to compensate the temporal lowering of v3. Thus threshold level Vt is obtained via signal V1 and black minimum level voltage V2 of black minimum level detection circuit 6. As a result, threshold voltage VT does not receive the effect of the photoelectric conversion signal due to the reflected light at the areas other than the original even in case the width of the original is small.
COPYRIGHT: (C)1979,JPO&Japio
JP6694378A 1978-06-02 1978-06-02 Automatic contrast adjusting device Granted JPS54158116A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP6694378A JPS54158116A (en) 1978-06-02 1978-06-02 Automatic contrast adjusting device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP6694378A JPS54158116A (en) 1978-06-02 1978-06-02 Automatic contrast adjusting device

Publications (2)

Publication Number Publication Date
JPS54158116A true JPS54158116A (en) 1979-12-13
JPS6126744B2 JPS6126744B2 (en) 1986-06-21

Family

ID=13330586

Family Applications (1)

Application Number Title Priority Date Filing Date
JP6694378A Granted JPS54158116A (en) 1978-06-02 1978-06-02 Automatic contrast adjusting device

Country Status (1)

Country Link
JP (1) JPS54158116A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02300863A (en) * 1989-05-15 1990-12-13 Nissan Motor Co Ltd Picture processor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04203024A (en) * 1990-11-30 1992-07-23 Nippon Steel Corp Circular forms made of plate for foundation bed

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5234611A (en) * 1975-09-11 1977-03-16 Nippon Signal Co Ltd:The Communication system and its equipment
JPS52157715U (en) * 1976-05-25 1977-11-30
JPS5330216A (en) * 1976-09-01 1978-03-22 Mitsubishi Electric Corp Dinary signal control circuit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5234611A (en) * 1975-09-11 1977-03-16 Nippon Signal Co Ltd:The Communication system and its equipment
JPS52157715U (en) * 1976-05-25 1977-11-30
JPS5330216A (en) * 1976-09-01 1978-03-22 Mitsubishi Electric Corp Dinary signal control circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02300863A (en) * 1989-05-15 1990-12-13 Nissan Motor Co Ltd Picture processor

Also Published As

Publication number Publication date
JPS6126744B2 (en) 1986-06-21

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