Electronic hearing aid control circuit
First Claim
1. A hearing aid control circuit for setting a predetermined maximum sound pressure level that a hearing aid will produce in response to a large electric input signal comprising, in combination:
- power source means for providing electric power to said hearing aid control circuit;
amplifier means for receiving said electric input signal and producing an amplified signal in response thereto;
feedback stage means, interconnected to said amplifier means, for receiving said amplified signal and producing a feedback signal in response to said amplified signal, said feedback signal including a feedback current;
output stage means, interconnected to said amplifier means, for receiving said amplified signal and producing an output signal in response to said amplified signal, said output signal defining a maximum output signal level and including an output current;
current regulator means, cooperatively defined by said feedback stage means and output stage means, for maintaining said feedback and output currents in a substantially proportional relationship, whereby said output current may be monitored by sensing said feedback current;
output transducer means, interconnected to said output stage means, for receiving said output signal and responsively providing an acoustic output;
a variable resistor, having a variable setting and interconnected between said power source means and said output transducer means, for adjustably limiting said maximum output signal level applied to said output transducer means; and
feedback line means, interconnecting said feedback stage means and variable resistor to said amplifier means, for exerting control over said output signal, said control being dependent upon said setting of said variable resistor.
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Accused Products
Abstract
An electronic power control circuit for a hearing aid amplifier. The circuit includes a feedback stage, output stage, and output transducer. The feedback and output stages cooperatively define a current regulator that controls the current of the output stage. A variable resistor is provided for adjusting the maximum signal level that can be applied to the output transducer in the hearing aid. Such adjustment prohibits the output transducer from producing an undesirably loud acoustic output. Adjustment of the variable resistor also simultaneously varies both the quiescent current of the output stage and the hearing aid gain.
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Citations
12 Claims
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1. A hearing aid control circuit for setting a predetermined maximum sound pressure level that a hearing aid will produce in response to a large electric input signal comprising, in combination:
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power source means for providing electric power to said hearing aid control circuit; amplifier means for receiving said electric input signal and producing an amplified signal in response thereto; feedback stage means, interconnected to said amplifier means, for receiving said amplified signal and producing a feedback signal in response to said amplified signal, said feedback signal including a feedback current; output stage means, interconnected to said amplifier means, for receiving said amplified signal and producing an output signal in response to said amplified signal, said output signal defining a maximum output signal level and including an output current; current regulator means, cooperatively defined by said feedback stage means and output stage means, for maintaining said feedback and output currents in a substantially proportional relationship, whereby said output current may be monitored by sensing said feedback current; output transducer means, interconnected to said output stage means, for receiving said output signal and responsively providing an acoustic output; a variable resistor, having a variable setting and interconnected between said power source means and said output transducer means, for adjustably limiting said maximum output signal level applied to said output transducer means; and feedback line means, interconnecting said feedback stage means and variable resistor to said amplifier means, for exerting control over said output signal, said control being dependent upon said setting of said variable resistor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A hearing aid control circuit for setting a predetermined maximum sound pressure level that a hearing aid will produce in response to a large electric input signal comprising, in combination:
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power source means for providing electric power to said hearing aid control circuit; amplifier means for receiving said electric input signal and producing an amplified signal in response thereto; feedback stage means, interconnected to said amplifier means, for receiving said amplified signal and producing a feedback signal in response to said amplified signal, said feedback signal including a feedback current; output stage means, interconnected to said amplifier means, for receiving said amplified signal and producing an output signal in response to said amplified signal, said output signal defining a maximum output signal level and including an output current; current regulator means, cooperatively defined by said feedback stage means and output stage means, for maintaining said feedback and output currents in a substantially proportional relationship, whereby said output current may be monitored by sensing said feedback current; output transducer means, interconnected to said output stage means, for receiving said output current and responsively providing an acoustic output; a variable resistor, having a variable setting and connected in series with said output transducer means, for adjustably limiting said maximum output signal level applied to said output transducer means; and feedback line means, interconnecting said feedback stage means and output stage means to said amplifier for exerting control over said output signal, said control being dependent upon said setting of said variable resistor. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification