US3567868A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interphone device having presence indicator means
Assignee: Toshiba Corp
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Filing: 1968-08-27
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Granted: 1971-03-02
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Expires: 1988-08-27
Abstract
Abstract An interphone designed for mutual conversation-type interphone systems and having a plurality of high impedance lamps the turning-on of which indicates the presence of personnel by the corresponding other interphones. A capacitor is connected to the lamp source supply lines for preventing crosstalk.
Inventors
- 👤 Toru Mukae
- 👤 Tadashi Akiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:33
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/002; H04M9/003
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
192 words
In an interphone apparatus comprising: a plurality of mutual speaking-type interphones; interphone source supply lines coupled to said interphones; speaking lines, the number of which corresponds to the number of said interphones, connected to said interphones; lamp source supply lines provided separately from said interphone source lines and said speaking lines and connected to said interphones; and the improvement wherein each interphone has presence indication means including: a high impedance lamp circuit which is connected at one end to the negative side of said lamp source supply lines and at the other end to said speaking lines; a lamp-switching circuit which is connected at one end to the negative side of said lamp source supply lines and at the other end to the lamps of at least another interphone through a corresponding speaking line for indicating the presence of personnel, operation of said lamp switching circuit at one interphone causing the lamp circuit of said another interphone to turn on, thereby indicating at said another interphone the presence of personnel at said one interphone; and a capacitor for crosstalk prevention connected between said interphone source lines and said lamp source supply lines.
Claim 2
Dependent Claim
192 words
In an interphone apparatus comprising: a plurality of mutual speaking-type interphones; interphone source supply lines coupled to said interphones; speaking lines, the number of which corresponds to the number of said interphones, connected to said interphones; lamp source supply lines provided separately from said interphone source lines and said speaking lines and connected to said interphones; and the improvement wherein each interphone has presence indication means including: a high impedance lamp circuit which is connected at one end to the negative side of said lamp source supply lines and at the other end to said speaking lines; a lamp-switching circuit which is connected at one end to the negative side of said lamp source supply lines and at the other end to the lamps of at least another interphone through a corresponding speaking line for indicating the presence of personnel, operation of said lamp switching circuit at one interphone causing the lamp circuit of said another interphone to turn on, thereby indicating at said another interphone the presence of personnel at said one interphone; and a capacitor for crosstalk prevention connected between said interphone source lines and said lamp source supply lines.
Claim 3
Dependent Claim
48 words
The interphone apparatus according to claim 1 in which said high impedance lamp circuit comprises a group of series circuits each of which includes a neon lamp connected to respective speaking lines and a lamp protection resistance connnected to the negative side of the lamp source supply lines.
Claim 4
Dependent Claim
46 words
The interphone apparatus according to claim 5 in which said lamp-switching circuit comprises a series circuit which includes a resistor connected to the positive side of said lamp source feed lines, a choke coil and a switch connected to a speaking line corresponding to said interphone.
Claim 5
Dependent Claim
29 words
The interphone apparatus according to claim 2 in which the number of said series circuits forming said high impedance lamp circuit corresponds to the number of said speaking lines.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |