JPS52141104A - Private talk system for telephone unit - Google Patents

Private talk system for telephone unit

Info

Publication number
JPS52141104A
JPS52141104A JP5749476A JP5749476A JPS52141104A JP S52141104 A JPS52141104 A JP S52141104A JP 5749476 A JP5749476 A JP 5749476A JP 5749476 A JP5749476 A JP 5749476A JP S52141104 A JPS52141104 A JP S52141104A
Authority
JP
Japan
Prior art keywords
telephone unit
talk
talk system
private
private talk
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
JP5749476A
Other languages
Japanese (ja)
Other versions
JPS5551375B2 (en
Inventor
Juichi Takano
Koichi Sekiguchi
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.)
Iwatsu Electric Co Ltd
Original Assignee
Iwatsu Electric 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 Iwatsu Electric Co Ltd filed Critical Iwatsu Electric Co Ltd
Priority to JP5749476A priority Critical patent/JPS52141104A/en
Publication of JPS52141104A publication Critical patent/JPS52141104A/en
Priority to US05/967,017 priority patent/US4254306A/en
Publication of JPS5551375B2 publication Critical patent/JPS5551375B2/ja
Granted legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/68—Circuit arrangements for preventing eavesdropping

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)

Abstract

PURPOSE:To carry out the private talk through detection of existence of the previous call checking the electric potential or polarity between the control lines, and thus to secure a smooth talk even at the time of the service interruption or the extension line talk.
JP5749476A 1975-12-26 1976-05-19 Private talk system for telephone unit Granted JPS52141104A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP5749476A JPS52141104A (en) 1976-05-19 1976-05-19 Private talk system for telephone unit
US05/967,017 US4254306A (en) 1975-12-26 1978-12-06 Key telephone system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5749476A JPS52141104A (en) 1976-05-19 1976-05-19 Private talk system for telephone unit

Publications (2)

Publication Number Publication Date
JPS52141104A true JPS52141104A (en) 1977-11-25
JPS5551375B2 JPS5551375B2 (en) 1980-12-24

Family

ID=13057269

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5749476A Granted JPS52141104A (en) 1975-12-26 1976-05-19 Private talk system for telephone unit

Country Status (1)

Country Link
JP (1) JPS52141104A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56149158A (en) * 1980-04-21 1981-11-18 Nitsuko Ltd Key telephone set
JPS5725767A (en) * 1980-07-22 1982-02-10 Iwatsu Electric Co Ltd Telephone device
JPS5725786A (en) * 1980-07-22 1982-02-10 Iwatsu Electric Co Ltd Changeover talking circuit during service interruption

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS494962A (en) * 1972-04-27 1974-01-17
JPS4996604A (en) * 1973-01-13 1974-09-12

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS494962A (en) * 1972-04-27 1974-01-17
JPS4996604A (en) * 1973-01-13 1974-09-12

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56149158A (en) * 1980-04-21 1981-11-18 Nitsuko Ltd Key telephone set
JPS5725767A (en) * 1980-07-22 1982-02-10 Iwatsu Electric Co Ltd Telephone device
JPS5725786A (en) * 1980-07-22 1982-02-10 Iwatsu Electric Co Ltd Changeover talking circuit during service interruption
JPH0213520B2 (en) * 1980-07-22 1990-04-04 Iwasaki Tsushinki Kk

Also Published As

Publication number Publication date
JPS5551375B2 (en) 1980-12-24

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