Audio system for minimizing the chance that high power audio signals may be directed to a headphone jack
First Claim
11. A system for detecting and compensating a voltage in a headphone, comprising:
- a headphone jack having a jack tip contact, a jack ring contact, and a jack sleeve contact adapted to receive a headphone plug having a plug tip, a plug ring, and a plug sleeve;
a power amplifier for generating reference audio signals having a predetermined voltage;
a speaker-headphone control generating a d.c. offset with a predetermined series resistance applied to the jack tip, jack ring, and jack sleeve contacts of the headphone jack, where the speaker headphone control provides a voltage comparison between at least one of the contacts of the headphone jack and the predetermined voltage when the headphone plug is inserted into the headphone jack such that a difference in voltage between the at least one of the contacts of the headphone jack and the predetermined voltage provides a reverse output state; and
a microprocessor detecting the reverse output state from the speaker headphone control provides a feedback control signal to the power amplifier to adjust the reference audio signal voltages to compensate the audio signal voltages for the headphone.
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Accused Products
Abstract
This invention provides a speaker system that minimizes the number of wires used to provide power and audio signal to all of the speakers. This is accomplished by without generating interference noises from shared signal wire implementations. The invention also provides a methodology for reducing power signals from being transmitted to headphones inserted into a headphone jack. The invention may use four wires to operate the speaker system. A first wire may be used to provide the control data signal common and control power common, and, if a headphone is used, the first wire may also serve as a common ground connection for the earpieces in the headphone. The second wire may provide a substantially constant current, so that constant current may be carried in the first wire regardless of the voltage on the second power/data wire. This way, the first wire may serve as a common control circuitry and the headphone as well. There may be no interference associated with sharing the first wire because constant current may be provided as a source of power that is independent of the voltage that appears on the second wire in the system. If a headphone is used, the current may be substantially constant in the second wire so that the voltage change in the second wire may not change the voltage in the first wire. Without the voltage change in the first wire, the signals to the headphone is not disturbed.
13 Citations
19 Claims
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11. A system for detecting and compensating a voltage in a headphone, comprising:
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a headphone jack having a jack tip contact, a jack ring contact, and a jack sleeve contact adapted to receive a headphone plug having a plug tip, a plug ring, and a plug sleeve;
a power amplifier for generating reference audio signals having a predetermined voltage;
a speaker-headphone control generating a d.c. offset with a predetermined series resistance applied to the jack tip, jack ring, and jack sleeve contacts of the headphone jack, where the speaker headphone control provides a voltage comparison between at least one of the contacts of the headphone jack and the predetermined voltage when the headphone plug is inserted into the headphone jack such that a difference in voltage between the at least one of the contacts of the headphone jack and the predetermined voltage provides a reverse output state; and
a microprocessor detecting the reverse output state from the speaker headphone control provides a feedback control signal to the power amplifier to adjust the reference audio signal voltages to compensate the audio signal voltages for the headphone. - View Dependent Claims (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 15, 16, 17, 18, 19)
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13-1. The system according to claim 12, where the speaker headphone control further includes:
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a first filter coupled to the first network to shunt high frequencies to a system ground;
a second filter coupled to the second network to shunt high frequencies to the system ground; and
a comparator receiving inputs from the first and second filters for the voltage comparison between the at least one of the contacts of the headphone jack and the predetermined voltage and providing an output state to the microprocessor.
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14. A method for detecting and compensating a voltage in a headphone, comprising:
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sensing contact voltages of a headphone jack having a jack tip contact, jack ring contact, and jack sleeve contact;
providing a reference audio signal having a predetermined voltage;
providing d.c. voltages having predetermined series resistances on at least one of the headphone jack contacts;
comparing the headphone jack contact d.c. voltages to the predetermined voltage;
generating a control signal due to the compared voltage; and
adjusting the reference audio signal voltage to compensate for the audio signal voltages to a headphone.
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Specification