JPS57194660A - Telephone circuit switching device - Google Patents

Telephone circuit switching device

Info

Publication number
JPS57194660A
JPS57194660A JP7863181A JP7863181A JPS57194660A JP S57194660 A JPS57194660 A JP S57194660A JP 7863181 A JP7863181 A JP 7863181A JP 7863181 A JP7863181 A JP 7863181A JP S57194660 A JPS57194660 A JP S57194660A
Authority
JP
Japan
Prior art keywords
telephone
telephone circuit
output
hook
switching device
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
JP7863181A
Other languages
Japanese (ja)
Inventor
Kouichirou Nitsutou
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.)
Hitachi Ltd
Original Assignee
Hitachi 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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP7863181A priority Critical patent/JPS57194660A/en
Publication of JPS57194660A publication Critical patent/JPS57194660A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/22—Arrangements for supervision, monitoring or testing
    • H04M3/2272—Subscriber line supervision circuits, e.g. call detection circuits

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)

Abstract

PURPOSE:To obtain a telephone circuit switching device which can assuredly obtain the hook information with a small size, a low cost and high voltage resistance, by putting a photocoupler in series into a telephone circuit and using the output of the telephone circuit as the hook information. CONSTITUTION:When a telephone set 3 is hooked off, a current flows to a photocoupler 53A or 53B from a current supply source E of a telephone exchange 1 via a telephone circuit 2 and in accordance with the polarity. Thus the inputs of the Schmitt triggers 53C and 53D receive the division of voltage through the resitances R and R1-R4. The output singals of the triggers are opposite to each other. As a result, the output signal of a gate 53E is set at H level to show the off-hook state. When the telephone set 3 is hooked on, no current flows to both photocouplers 53A and 53B. Thus the gate output is set at L level to show the off-hook state. Furthermore the on-hook state is assuredly obtained through the time constant circuits R and C although the call signal is transmitted.
JP7863181A 1981-05-26 1981-05-26 Telephone circuit switching device Pending JPS57194660A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP7863181A JPS57194660A (en) 1981-05-26 1981-05-26 Telephone circuit switching device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7863181A JPS57194660A (en) 1981-05-26 1981-05-26 Telephone circuit switching device

Publications (1)

Publication Number Publication Date
JPS57194660A true JPS57194660A (en) 1982-11-30

Family

ID=13667216

Family Applications (1)

Application Number Title Priority Date Filing Date
JP7863181A Pending JPS57194660A (en) 1981-05-26 1981-05-26 Telephone circuit switching device

Country Status (1)

Country Link
JP (1) JPS57194660A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6276354A (en) * 1985-09-27 1987-04-08 Nec Eng Ltd Hook-off detection circuit
JPS63129351U (en) * 1987-02-17 1988-08-24
JPH01276868A (en) * 1988-04-27 1989-11-07 Ricoh Co Ltd Facsimile equipment
JPH03285443A (en) * 1990-03-30 1991-12-16 Sharp Corp Facsimile equipment

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55134568A (en) * 1979-04-06 1980-10-20 Nippon Telegr & Teleph Corp <Ntt> Data collector
JPS56115062A (en) * 1980-02-15 1981-09-10 Tamura Electric Works Ltd Telephone hook-off and call signal detecting circuit
JPS5731256A (en) * 1980-08-01 1982-02-19 Oki Electric Ind Co Ltd Ncu circuit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55134568A (en) * 1979-04-06 1980-10-20 Nippon Telegr & Teleph Corp <Ntt> Data collector
JPS56115062A (en) * 1980-02-15 1981-09-10 Tamura Electric Works Ltd Telephone hook-off and call signal detecting circuit
JPS5731256A (en) * 1980-08-01 1982-02-19 Oki Electric Ind Co Ltd Ncu circuit

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6276354A (en) * 1985-09-27 1987-04-08 Nec Eng Ltd Hook-off detection circuit
JPS63129351U (en) * 1987-02-17 1988-08-24
JPH01276868A (en) * 1988-04-27 1989-11-07 Ricoh Co Ltd Facsimile equipment
JPH03285443A (en) * 1990-03-30 1991-12-16 Sharp Corp Facsimile equipment

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