System and method for generating an audio signal
Techniques described herein generally relate to generating an audio signal with a speaker. In some examples, a speaker device is described that includes a membrane and a shutter and driver device is configured to receive an audio signal, modulate it and generate electric signals to operate the speaker and generate an acoustic audio signal.
1 . A driver device for operating a speaker comprising:
a power source;
two or more voltage drivers each including a MEMS driver configured to receive voltage from the power source;
a controller;
wherein the speaker includes at least a membrane and a shutter, and
wherein the controller is configured to receive a digital audio signal and operate the two or more voltage drivers such that at least one of the voltage drivers drives the membrane with a pulsed electrical signal comprising at least two or more voltage levels and another of the voltage drivers drives the shutter with a pulsed electrical signal comprising at least two or more voltage levels to generate an audio signal from the speaker.
2 . The driver device according to claim 1 , where the power source is one of: a step up convertor; a charge pump; or a battery voltage.
3 . The driver device according to claim 1 , where the power source and the MEMS driver are combined in one functional unit with an output voltage smaller than a target drive signal voltage.
4 . The driver device according to claim 3 , where multiple combined power source and MEMS driver are configured so that the summation of voltages thereof provides a required drive signal voltage.
5 . The driver device according to claim 1 , where the controller is configured to operate by: receiving an audio signal; modulation of the audio signal; wherein at least one MEMS driver is configured to provide a voltage according to the modulated audio signal and at least a second MEMS driver is configured to provide an oscillating voltage at a modulation frequency.
6 . The driver device according to claim 1 , where the controller is configured to operate by: receiving an audio signal; predistortion of the audio signal; wherein at least one MEMS driver is configured to provide an oscillating voltage at a target frequency with a phase defined by the pre-distorted audio signal and at least a second MEMS driver is configured to provide an oscillating voltage at a target frequency.
7 . The driver device according to claim 6 , where the target frequency is in the range between 100 KHz and 1 MHz.
8 . The driver device of claim 1 , wherein the controller is configured to generate a single side band modulated audio signal and to convert the single side band modulated audio signal into a binary signal received by the voltage drivers.
9 . A driver device and speaker structure comprising:
a speaker comprising:
at least one membrane positioned in a first plane and configured to oscillate along a first directional path and at a first frequency effective to generate an ultrasonic acoustic signal; and
a shutter positioned in a second plane that is substantially separated from the first plane; and
a driver device comprising:
a power source;
first and second MEMS voltage drivers configured to receive voltage from the power source;
a controller;
wherein the controller is configured to receive an input audio signal and 1) operate the first MEMS voltage driver with a pulsed electrical signal comprising at least two or more voltage levels to generate a modulated audio signal to operate the at least one membrane and 2) operate the second MEMS voltage driver with a pulsed electrical signal comprising at least two or more voltage levels to generate an ultrasonic modulated signal and operate the shutter at the modulation frequency to demodulate the ultrasonic modulated signal and generate an acoustic audio signal.
10 . The structure according to claim 9 , where the power source is any of step up convertor; a charge pump; a battery voltage.
11 . The structure according to claim 9 , where the power source and the first and second MEMS voltage driver are combined in one functional unit with an output voltage smaller than a target drive signal voltage.
12 . The structure according to claim 11 , where multiple combined power source and the first and second MEMS voltage driver are configured so that the summation of voltages thereof provides a required drive signal voltage.
13 . The structure according to claim 9 , where the controller is configured to operate by; receiving an audio signal; modulation of the audio signal; wherein the first MEMS voltage driver is configured to provide a pulsed electrical signal with at least two voltage levels according to the modulated audio signal and the second MEMS voltage driver is configured to provide an oscillating pulsed electrical signal with at least two voltage levels at a modulation frequency.
14 . The structure according to claim 9 , where the controller is configured to operate by; receiving an audio signal; predistortion of the audio signal; wherein the first MEMS voltage driver is configured to provide an oscillating pulsed electrical signal with at least two voltage levels at a target frequency with a phase defined by the pre-distorted audio signal and the second MEMS voltage driver is configured to provide an oscillating pulsed electrical signal with at least two voltage levels at a target frequency.
15 . The structure according to claim 14 , where the target frequency is in the range between 100 KHz and 1 MHz.
16 . The structure of claim 9 , wherein the controller is configured to generate a single side band modulated audio signal and to convert the single side band modulated audio signal into a binary signal received by the voltage drivers.
17 . A driver device for operating a speaker, the speaker having a membrane and a shutter, the driver device comprising:
a controller;
a charge pump configured to generate a high voltage signal;
a first MEMS driver and a second MEMS driver configured to modulate the high voltage signal,
wherein the controller is configured to receive a digital sound data stream and an operating voltage and operate the first MEMS driver to generate a pulsed electrical signal with at least two voltage levels to drive the membrane and operate the second MEMS driver to generate a pulsed electrical signal with at least two voltage levels to drive the shutter to generate an audio signal from the speaker.
18 . The driver device of claim 17 , wherein the controller, charge pump and switching unit are part of a semiconductor integrated circuit.
19 . The driver device of claim 17 , wherein the controller is configured to generate a single side band modulated audio signal and to convert the single side band modulated audio signal into a binary signal received by the voltage drivers.