US4485273A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Intercom adapter for telephones
Assignee: Individual
•
Filing: 1982-09-23
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Granted: 1984-11-27
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Expires: 2002-09-23
Abstract
Abstract Apparatus for adapting a standard telephone set for use in an intercom system communicating over the two "extra" conductors of the four-conductor wiring typically provided on the premises of a telephone subscriber. The adapter is inserted between the telephone and the premises wiring. A hold button, intercom signaling button, intercom select switch, and various indicators are provided by the adapter, which provides these features without requiring separate connection to a power source. The hold function automatically releases at the end of a conversation. Indicators warn the user to switch from intercom to central office when an incoming call is present and the intercom is selected. The intercom is usable even when the central office line is out of order.
Inventors
- 👤 Everhard H. B. Bartelink
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:06
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/71; H04M1/715
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
153 words
An intercom adapter for connecting a line from a user's communications terminal to one of either the line to a communications switching center or a local intercom line, said adapter comprising: off-hook detection means for detecting an off-hook condition in the communications terminal; first control means for a user of the communications terminal to choose between connection of the communications terminal either to the remote communications center or connection to the intercom line; and transfer means for transferring the communications terminal selectively between the remote communications center and the intercom line, said transfer means being responsive to said off-hook detection means and said first control means such that the communications terminal is connected to the intercom line when both the user has selected the intercom and an off-hook condition is detected and the communications terminal is connected to the remote communications center when at least one of these two conditions is not met.
Claim 2
Dependent Claim
153 words
An intercom adapter for connecting a line from a user's communications terminal to one of either the line to a communications switching center or a local intercom line, said adapter comprising: off-hook detection means for detecting an off-hook condition in the communications terminal; first control means for a user of the communications terminal to choose between connection of the communications terminal either to the remote communications center or connection to the intercom line; and transfer means for transferring the communications terminal selectively between the remote communications center and the intercom line, said transfer means being responsive to said off-hook detection means and said first control means such that the communications terminal is connected to the intercom line when both the user has selected the intercom and an off-hook condition is detected and the communications terminal is connected to the remote communications center when at least one of these two conditions is not met.
Claim 3
Dependent Claim
68 words
The intercom adapter of claim 1 further comprising two conductors, each connecting to a conductor in the intercom line; and wherein: said first control means comprises a first switch; said transfer means comprises a transfer device; said off-hook detection means completes a circuit upon the detection of the off-hook condition; and said first switch, said circuit, and said transfer device are connected in series across said two conductors.
Claim 4
Dependent Claim
20 words
The intercom adapter of claim 2 wherein said two conductors are connected to the intercom line through a diode bridge.
Claim 5
Dependent Claim
67 words
The intercom adapter of claims 1, 2, or 3 further comprising: second control means for responding to a command from a user of the telephone to generate a ring signal on the intercom line; indicator means responsive to a ring signal on the intercom line; and generation means for generating a ring signal on the intercom line, said generation means being responsive to said second control means.
Claim 6
Dependent Claim
40 words
The intercom adapter of claim 4 wherein said second control means further activates said transfer means to connect the remote communications center to the intercom line even though the line to the remote control center may be out of order.
Claim 7
Dependent Claim
82 words
The intercom adapter of claims 1, 2, or 3 further comprising: third control means responsive to a command from a user of the communications terminal to place the line to the remote communications center in a hold state; and loading means for selectively loading the line to effect a hold condition, said loading means being initially activated in response to said third control means and remaining activated only as long as an off-hook condition exists on the line to the communications terminal.
Claim 8
Dependent Claim
33 words
The intercom adapter of claims 1, 2, or 3 further comprising a resistor, said resistor being in series with one conductor of the intercom line between the intercom line and the transfer means.
Claim 9
Dependent Claim
37 words
The intercom adapter of claims 1, 2, or 3 further comprising a resistor bridged by a condenser, said resistor being in series with one conductor of the intercom line between the intercom line and the transfer means.
Claim 10
Dependent Claim
64 words
The intercom adapter of claims 1, 2, or 3 further comprising: means for detecting a ring signal on the line from the central office; and detection means responsive to a ring signal on the line from the communications terminal; generation means for generating a ring signal on the intercom line, said ring generation means being responsive to said means for detecting a ring signal.
Claim 11
Dependent Claim
33 words
The intercom adapter of claims 1, 2, or 3 further comprising means for indicating to a user of the telephone the presence of a ring signal on the line from the communications center.
Claim 12
Dependent Claim
29 words
The intercom adapter of claims 1, 2, or 3 wherein said off-hook detection means is sufficiently slow acting to avoid responding to dial pulses transmitted by the communications terminal.
Claim 13
Dependent Claim
87 words
The intercom adapter of claims 1, 2, or 3 wherein said off-hook detection means comprises: two optical isolator devices responsive to the presence of current in the communications terminal line, of which one operates in response to current in one direction and the other operates in response to current in the other direction; and switching means for completing another circuit, said completing occuring when either of the optical isolator devices has operated, and said completing being inhibited when neither or both of the optical isolators have operated.
Claim 14
Dependent Claim
28 words
The intercom adapter of claim 11 in which the communications terminal is a telephone and further comprising means for making the off-hook detection means insensitive to dial pulses.
Claim 15
Dependent Claim
125 words
In a system containing a first two-wire circuit which gives access to a telephone company central office or to other communications devices, containing a second two-wire circuit serving as an intercom circuit and containing a third two-wire circuit leading to the user's telephone set or other communications terminal, an intercom adapter interconnecting these circuits, said adapter comprising a transfer device, a switch and a control circuit, which control circuit contains means for detecting an off-hook condition in the third circuit and which, when detecting the off-hook condition completes a circuit through the transfer device, thereby causing it to connect the third circuit to the second circuit, but during only those periods when, in addition, the switch is in the closed position, thereby completing the circuit.
Claim 16
Dependent Claim
125 words
In a system containing a first two-wire circuit which gives access to a telephone company central office or to other communications devices, containing a second two-wire circuit serving as an intercom circuit and containing a third two-wire circuit leading to the user's telephone set or other communications terminal, an intercom adapter interconnecting these circuits, said adapter comprising a transfer device, a switch and a control circuit, which control circuit contains means for detecting an off-hook condition in the third circuit and which, when detecting the off-hook condition completes a circuit through the transfer device, thereby causing it to connect the third circuit to the second circuit, but during only those periods when, in addition, the switch is in the closed position, thereby completing the circuit.
Claim 17
Dependent Claim
25 words
In the system of claim 14, impedance means connected between the second circuit and the third circuit to limit current flow into the third circuit.
Claim 18
Dependent Claim
23 words
A system according to claim 15 in which the impedance means comprises a resistance connected between the second circuit and the third circuit.
Claim 19
Dependent Claim
25 words
A system according to claim 15 that includes capacitance means by-passing the impedance means to provide a low-impedance path for speech and other communications current.
Claim 20
Independent Claim
124 words
A method of effecting switching between communications channels in a system containing a first two-wire circuit which gives access to communications devices, containing a second two-wire circuit serving as an intercom circuit and containing a third two-wire circuit leading to a user's telephone set or other communications terminal, that comprises: connecting the third circuit leading to the user's telephone or other communications terminal to said first circuit through a transfer device, a switch and a control circuit, which control circuit detects an off-hook condition, connecting the third circuit to said second circuit through the transfer device only during those periods which (a) the switch is closed while and (b) at the same time an off-hook condition exists and is detected in said third circuit.
Claim 21
Independent Claim
124 words
A method of effecting switching between communications channels in a system containing a first two-wire circuit which gives access to communications devices, containing a second two-wire circuit serving as an intercom circuit and containing a third two-wire circuit leading to a user's telephone set or other communications terminal, that comprises: connecting the third circuit leading to the user's telephone or other communications terminal to said first circuit through a transfer device, a switch and a control circuit, which control circuit detects an off-hook condition, connecting the third circuit to said second circuit through the transfer device only during those periods which (a) the switch is closed while and (b) at the same time an off-hook condition exists and is detected in said third circuit.
References Cited (Backward Citations)
US4088846A
Cited
US4196317A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-11-27 | 1988-05-28 | 1988-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-27 | 1992-05-28 | 1992-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-27 | 1996-05-28 | 1996-11-27 | $7700.00 | Window Closed / Lapsed |