Audio system for minimizing the chance that high power audio signals may be directed to a headphone jack
View Patent ↗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.
1. A speaker system, comprising:
a first wire;
a second wire coupled to a current conveyor providing power and data, where the power is generated from a generator that provides a substantially constant current;
a microprocessor coupled to the current conveyor, where the microprocessor sends control voltage data to the current conveyor to vary the voltage on the second wire, where the current conveyor outputs a current that is substantially similar to current through the second wire that is substantially independent of the voltage in the second wire;
a shunt voltage regulator coupled to the output of the current conveyor and the first wire to shunt excess current through the first wire, and provide a substantially constant voltage to power the microprocessor, where the microprocessor is coupled to a control to detect an adjustment made by a user and based on the adjustment adjusting the control voltage data to the current conveyor to transmit the control voltage data to a data receiver so that the output of the data receiver corresponds in a predetermined way to the control voltage data;
third and fourth wires coupled to the generator, where the generator provides opposing polarity audio signal voltages to the third and fourth wires;
the third and fourth wires coupled to a speaker-headphone control (SHC), where the SHC produces a d.c. bias voltage in series with a predetermined resistance and applies the voltage to a sleeve conductor of a headphone jack and a first input of a voltage comparator, where the SHC produces a second d.c. bias voltage and applies it to a second input of the voltage comparator, and where the third and fourth wires are coupled to tip and ring connections of the headphone jack so that when a headphone plug is inserted into the headphone jack, the difference between the first and second d.c. bias voltages reverses the polarity compared to the difference prior to insertion of the headphone plug to reverse the output state of the voltage comparator; and
the microprocessor detecting the reverse in polarity of the output of the voltage comparator reverses the polarity of the d.c. bias voltages and directs the generator to lower the power level to the third and fourth wires which provide audio signal to a headphone, and directs the generator to make the signals on third and fourth wires to be the left and right channel signals.
2. The speaker system according to claim 1 , where the predetermined way is data stream substantially similar to the control voltage data from the microprocessor.
3. The speaker system according to claim 1 , where the predetermined way is an inverted replica of the control voltage data from the microprocessor.
4. The speaker system according to claim 1 , where the predetermined way outputs a delayed replica of the control voltage data from the microprocessor.
5. The speaker system according to claim 1 , where the generator powers a memory coupled to the microprocessor.
6. The speaker system according to claim 1 , further including:
a switch coupled to the headphone jack and ahead of a speaker driver;
the third wire coupled to an input side of the switch; and
the fourth wire coupled to the speaker driver, where the switch is open when the headphone plug is fully inserted into the headphone jack.
7. The speaker system according to claim 1 , where the control includes a knob control and a mode button to allow a user to make adjustments to the speaker system.
8. The speaker system according to claim 7 , further including a plurality of light emitting diodes (LEDs) coupled to the microprocessor to display the adjustments made by the user.
9. The speaker system according to claim 1 , where the generator is housed in a subwoofer.
10. 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, and the audio signals from the power amplifier outputs first and second signals having opposing voltage polarity;
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 headpbone 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;
where the speaker headphone control includes first and second summing and voltage offset networks receiving the first and second signals from the power amplifier, the first and second networks each having a voltage with the predetermined series resistance substantially equal to an average voltage on the first and second signals with the d.c. offset.
11. The system according to claim 10 , where the speaker headphone control further includes:
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.