Muting circuit for telephone answering machine
First Claim
1. Apparatus, comprising:
- an answering machine which plays out a greeting message over a telephone line to which it is coupled in response to an incoming call; and
a voltage breakdown circuit coupled in series between a subcircuit of said answering machine and said telephone line, said voltage breakdown circuit becoming conductive only when the voltage across said telephone line exceeds a predetermined threshold level.
3 Assignments
0 Petitions
Accused Products
Abstract
A voltage breakdown circuit is connected in series between telephone answering machine circuitry and a telephone line. The voltage breakdown device becomes conductive only when the voltage across its terminals exceeds a predetermined level. If a telephone connected to the same telephone line as the answering machine circuitry is placed in the off hook condition, the voltage across the voltage breakdown device falls below the threshold level and the answering machine circuitry is effectively cut off from the telephone line. The voltage breakdown circuit is also useful in defeating automatic recording equipment placed in parallel with a telephone. Such automatic recording equipment is automatically disabled whenever the voltage across the tip in ring terminals of a telephone line is above a predetermined level. By placing the voltage breakdown circuit in series with a telephone which is to be protected from such taping, an automatic recording device connected in parallel with the telephone will automatically be disabled when the telephone is placed in the off hook condition.
28 Citations
28 Claims
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1. Apparatus, comprising:
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an answering machine which plays out a greeting message over a telephone line to which it is coupled in response to an incoming call; and a voltage breakdown circuit coupled in series between a subcircuit of said answering machine and said telephone line, said voltage breakdown circuit becoming conductive only when the voltage across said telephone line exceeds a predetermined threshold level. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus, comprising:
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automatic recording equipment coupled across the tip and ring terminals of a telephone line, said equipment being disabled whenever the voltage across said tip and ring terminals is above a predetermined level; and a telephone connected in series with a privacy device, said series connected telephone and privacy device being coupled across said tip and ring terminals in parallel with said recording equipment, said privacy device causing the voltage across said tip and ring terminals to be greater than said predetermined level when said telephone is in the off-hook condition. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. Telephone apparatus, comprising:
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first and second subcircuits connected in parallel with one another across the tip and ring terminals of a telephone line; said first subcircuit comprising a first telephone device; said second subcircuit comprising a second telephone device coupled in series with a semi-conductor latching means, said semi-conducted latching means being rendered conductive upon the activation of said second telephone device and subsequently being rendered non-conductive upon the subsequent activation of said first telephone device whereby said second telephone device is decoupled from said telephone line upon the activation of said first telephone device. - View Dependent Claims (16, 17, 18, 19, 20)
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21. Telephone apparatus, comprising:
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first and second subcircuits connected in parallel with one another across the tip and ring terminals of a telephone line; said first subcircuit comprising a telephone instrument and defining a first current path between said tip and ring terminals when said telephone instrument is in an off hook condition; said second subcircuit comprising a telephone answering machine for playing out a greeting message over said telephone line in response to an incoming telephone call and a greeting message muting circuit for muting said greeting message whenever said telephone instrument is placed in said off hook condition, said muting circuit including voltage level responsive means coupled serially between said telephone answering machine and said telephone line, said second subcircuit defining a second circuit path between said tip and ring terminals when said telephone answering machine plays out said greeting message, said greeting message muting circuit causing the impedance of said second circuit path to be greater than the impedance of said first current path when said telephone instrument is placed in the off hook condition whereby the current passing through said telephone line is substantially shunted away from said second circuit path when said telephone instrument is in said off hook condition thereby substantially muting said greeting message.
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22. Telephone apparatus, comprising:
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an answering machine coupled to a telephone line, said answering machine including circuit means for playing out a greeting message over said telephone line in response to an incoming call; and a voltage level sensing means operatively coupled in series between said circuit means and said telephone line, said voltage level sensing means being operative after said answering machine has answered an incoming call and being conductive only when the voltage across said telephone line exceeds a predetermined level.
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23. Telephone apparatus, comprising:
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an answering machine coupled to a telephone line, said answering machine including circuit means for playing out a greeting message over said telephone line in response to an incoming call; and a voltage level sensing means operatively coupled in series between said circuit means and said telephone line, said voltage level sensing means becoming conductive only when the voltage across said telephone line exceeds a predetermined level, said voltage level sensing means comprising a Zener diode.
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24. Telephone apparatus comprising:
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an answering machine coupled to a telephone line, said answering machine including circuit means for playing out a greeting message over said telephone line in response to an incoming call; a voltage level sensing means operatively coupled in series between said circuit means and said telephone line, said voltage level sensing means becoming conductive only when the voltage across said telephone line exceeds a predetermined level; and a latching circuit coupled in series with said voltage level sensing means. - View Dependent Claims (25, 26, 27)
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28. Telephone apparatus, comprising:
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an answering machine coupled to a telephone line, said answering machine including circuit means for playing out a greeting message over said telephone line in response to an incoming call; a voltage level sensing means operatively coupled in series between said circuit means and said telephone line, said voltage level sensing means becoming conductive only when the voltage across said telephone line exceeds a predetermined level; said predetermined level being of a sufficient magnitude as to cause said greeting message to be substantially attenuated when a telephone also coupled to said telephone line in parallel with said answering machine is in an off hook condition while said message is being played out.
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Specification