US3716672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modem cbs/cbt interface
Assignee: Design Elements Inc
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Filing: 1971-08-09
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Granted: 1973-02-13
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Expires: 1991-08-09
Abstract
Abstract A logic interface circuit for providing appropriate on hook and off hook output states to the QH-DA terminal of either a CBS or CBT type telephone data link system. The appropriate output occurs in response to the command of the modem control logic without the necessity of switching or adapting the modem circuit during installation to the CBS or CBT system in which it is installed.
Inventors
- 👤 R Fretwell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:37
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/06
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
397 words
A CBS/CBT interface for providing appropriate on hook and off hook output conditions at a telephone OH-DA terminal in response to input conditions at three input terminals, the first input terminal connected to a control logic output which is effectively connected to ground for an off hook instruction and to a very high impedance for an on hook instruction, the second input terminal being a ring terminal and the third input terminal being a CCT terminal, the interface also being connected to a positive power supply and to A negative power supply intermediately connected to ground, said interface comprising: a. ''''or'''' gate means having an input connected to said ring terminal and an input connected to said CCT terminal for providing a selected output condition in response to the presence of a negative potential at a gate means input; b. a first electronic switch means includes a control input terminal for switching said first switch means into conduction when said control input is grounded, the principal terminals of said first switch connected between said positive supply and said OH-DA terminal; c. a second electronic switch means having one of its principal terminals connected to said negative supply and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means; d. a third electronic switch means including a control input terminal and having its principal terminals connected between said OH-DA terminal and the other principal terminal of said second electronic switch means for being switched into nonconduction when its control input terminal is connected to ground; e. a fourth electronic switch means having its principal terminals connected between said first input terminal and said OH-DA terminal and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by the absence of said selected output of said ''''or'''' gate means; f. a fifth electronic switching means having its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means, having one of its principal terminals connected to said first input terminal and its other principal terminal connected to the control input terminal of said first electronic switch means and to the control input terminal of said third electronic switch means.
Claim 2
Dependent Claim
397 words
A CBS/CBT interface for providing appropriate on hook and off hook output conditions at a telephone OH-DA terminal in response to input conditions at three input terminals, the first input terminal connected to a control logic output which is effectively connected to ground for an off hook instruction and to a very high impedance for an on hook instruction, the second input terminal being a ring terminal and the third input terminal being a CCT terminal, the interface also being connected to a positive power supply and to A negative power supply intermediately connected to ground, said interface comprising: a. ''''or'''' gate means having an input connected to said ring terminal and an input connected to said CCT terminal for providing a selected output condition in response to the presence of a negative potential at a gate means input; b. a first electronic switch means includes a control input terminal for switching said first switch means into conduction when said control input is grounded, the principal terminals of said first switch connected between said positive supply and said OH-DA terminal; c. a second electronic switch means having one of its principal terminals connected to said negative supply and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means; d. a third electronic switch means including a control input terminal and having its principal terminals connected between said OH-DA terminal and the other principal terminal of said second electronic switch means for being switched into nonconduction when its control input terminal is connected to ground; e. a fourth electronic switch means having its principal terminals connected between said first input terminal and said OH-DA terminal and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by the absence of said selected output of said ''''or'''' gate means; f. a fifth electronic switching means having its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means, having one of its principal terminals connected to said first input terminal and its other principal terminal connected to the control input terminal of said first electronic switch means and to the control input terminal of said third electronic switch means.
Claim 3
Dependent Claim
397 words
A CBS/CBT interface for providing appropriate on hook and off hook output conditions at a telephone OH-DA terminal in response to input conditions at three input terminals, the first input terminal connected to a control logic output which is effectively connected to ground for an off hook instruction and to a very high impedance for an on hook instruction, the second input terminal being a ring terminal and the third input terminal being a CCT terminal, the interface also being connected to a positive power supply and to A negative power supply intermediately connected to ground, said interface comprising: a. ''''or'''' gate means having an input connected to said ring terminal and an input connected to said CCT terminal for providing a selected output condition in response to the presence of a negative potential at a gate means input; b. a first electronic switch means includes a control input terminal for switching said first switch means into conduction when said control input is grounded, the principal terminals of said first switch connected between said positive supply and said OH-DA terminal; c. a second electronic switch means having one of its principal terminals connected to said negative supply and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means; d. a third electronic switch means including a control input terminal and having its principal terminals connected between said OH-DA terminal and the other principal terminal of said second electronic switch means for being switched into nonconduction when its control input terminal is connected to ground; e. a fourth electronic switch means having its principal terminals connected between said first input terminal and said OH-DA terminal and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by the absence of said selected output of said ''''or'''' gate means; f. a fifth electronic switching means having its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means, having one of its principal terminals connected to said first input terminal and its other principal terminal connected to the control input terminal of said first electronic switch means and to the control input terminal of said third electronic switch means.
Claim 4
Dependent Claim
397 words
A CBS/CBT interface for providing appropriate on hook and off hook output conditions at a telephone OH-DA terminal in response to input conditions at three input terminals, the first input terminal connected to a control logic output which is effectively connected to ground for an off hook instruction and to a very high impedance for an on hook instruction, the second input terminal being a ring terminal and the third input terminal being a CCT terminal, the interface also being connected to a positive power supply and to A negative power supply intermediately connected to ground, said interface comprising: a. ''''or'''' gate means having an input connected to said ring terminal and an input connected to said CCT terminal for providing a selected output condition in response to the presence of a negative potential at a gate means input; b. a first electronic switch means includes a control input terminal for switching said first switch means into conduction when said control input is grounded, the principal terminals of said first switch connected between said positive supply and said OH-DA terminal; c. a second electronic switch means having one of its principal terminals connected to said negative supply and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means; d. a third electronic switch means including a control input terminal and having its principal terminals connected between said OH-DA terminal and the other principal terminal of said second electronic switch means for being switched into nonconduction when its control input terminal is connected to ground; e. a fourth electronic switch means having its principal terminals connected between said first input terminal and said OH-DA terminal and its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by the absence of said selected output of said ''''or'''' gate means; f. a fifth electronic switching means having its control input terminal connected to the output of said ''''or'''' gate means for being switched into conduction by said selected output of said ''''or'''' gate means, having one of its principal terminals connected to said first input terminal and its other principal terminal connected to the control input terminal of said first electronic switch means and to the control input terminal of said third electronic switch means.
Claim 5
Dependent Claim
58 words
A CBS/CBT interface according to claim 1 wherein said ''''or'''' gate means comprises a pair of diodes having interconnected anodes and having one cathode connected to said second input terminal and the other cathode connected to said third input terminal; and wherein said interconnected anodes are conductively connected to the base of a common emitter connected NPN transistor.
Claim 6
Dependent Claim
49 words
A CBS/CBT interface according to claim 1 wherein said first electronic switch means comprises a series connected diode, load resistance, and PNP transistor, its base being its control input terminal and having its emitter connected to said positive supply and its collector connected to the anode of said diode.
Claim 7
Dependent Claim
80 words
A CBS/CBT interface according to claim 3 wherein said third electronic switch means comprises a PNP transistor having its emitter connected to the cathode of said diode and its base connected to the anode of said diode; and wherein said second electronic switch means comprises a NPN transistor having its emitter connected to said negative supply, its collector connected to the collector of said third electronic switch means and its base connected to the output of said ''''or'''' gate means.
Claim 8
Dependent Claim
51 words
A CBS/CBT interface according to claim 1 wherein said fourth electronic switch means comprises a series connected diode and NPN transistor having its collector connected to the cathode of said diode, its emitter connected to said first input terminal and its base connected to the output of said ''''or'''' gate means.
Claim 9
Dependent Claim
97 words
A CBS/CBT interface according to claim 5 wherein said fourth electronic switch means includes a logic level shifting circuit connecting the base of said series connected NPN transistor to said ''''or'''' gate means output and comprising an NPN transistor having its emitter connected to said negative supply, its base connected to said ''''or'''' gate means output and its collector connected through a suitable load resistance to said positive supply, and a diode having its anode connected to the collector of said logic shifting transistor and its anode connected to the base of said series connected NPN transistor.
Claim 10
Dependent Claim
30 words
A CBS/CBT interface according to claim 1 wherein said fifth electronic switch means comprises a field effect transistor having its gate connected to the output of said ''''or'''' gate means.
Claim 11
Dependent Claim
335 words
A CBS/CBT interface according to claim 1 wherein said ''''or'''' gate means comprises a pair of diodes having interconnected anodes and having one cathode connected to said second input terminal and the other cathode connected to said third input terminal; and wherein said interconnected anodes are conductively connected to the base of a common emitter connected NPN transistor; and wherein said first electronic switch means comprises a series connected diode, load resistance, and PNP transistor, its base being its control input terminal and having its emitter connected to said positive supply and its collector connected to the anode of said diode; and wherein said third electronic switch means comprises a PNP transistor having its emitter connected to the cathode of said diode and its base connected to the anode of said diode; and wherein said second electronic switch means comprises a NPN transistor having its emitter connected to said negative supply, its collector connected to the collector of said third electronic switch means and its base connected to the output of said ''''or'''' gate means; and wherein said fourth electronic switch means comprises a series connected diode and NPN transistor having its collector connected to the cathode of said diode, its emitter connected to said first input terminal and its base connected to the output of said ''''or'''' gate means; and wherein said fourth electronic switch means includes a logic level shifting circuit connecting the base of said series connected NPN transistor to said ''''or'''' gate means output and comprising an NPN transistor having its emitter connected to said negative supply, its base connected to said ''''or'''' gate means output and its collector connected through a suitable load resistance to said positive supply, and a diode having its anode connected to the collector of said logic shifting transistor and its anode connected to the base of said series connected NPN transistor; and wherein said fifth electronic switch means comprises a field effect transistor having its gate connected to the output of said ''''or'''' gate means.
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) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |