Methods and apparatus for actuator control
Various embodiments of the present technology may comprise methods and apparatus for actuator control. The methods and apparatus may comprise various circuits and/or systems to generate a feedback signal according to an induced voltage and further generate various signal processing functions to selectively adjust a gain of the feedback signal. The apparatus for actuator control may comprise an induced voltage detection circuit and a feedback control circuit that operate together to generate the feedback signal used to control the actuator.
1. An actuator control circuit, comprising:
a drive circuit, coupled to the actuator and configured to supply a drive signal to the actuator; and
a feedback network connected to the drive circuit and configured to generate a feedback signal, wherein the feedback network comprises:
an induced voltage detection circuit connected to an output terminal of the drive circuit; and
a feedback control circuit configured to:
attenuate a portion of the feedback signal that falls outside of a predetermined frequency range; and
adjust a gain of the feedback signal.
2. The actuator control circuit according to claim 1 , wherein the feedback control circuit comprises:
a band-pass filter; and
a gain control circuit connected to an output terminal of the band-pass filter.
3. The actuator control circuit according to claim 2 , wherein the gain control circuit comprises:
an amplifier;
a first switch connected between the band-pass filter and an input terminal of the amplifier; and
a second switch connected to an output terminal of the amplifier.
4. The actuator control circuit according to claim 3 , wherein:
the amplifier is configured to adjust the gain of the feedback signal according to a counter value; and
the first and second switches are operated according to the counter value.
5. The actuator control circuit according to claim 1 , wherein the feedback control circuit is further configured to:
decrease the gain of the feedback signal for a first count period; and
increase the gain of the feedback signal for a second count period.
6. The actuator control circuit according to claim 5 , wherein the control circuit is further configured to disable the feedback control circuit for a period of time between the first count period and the second count period.
7. The actuator control circuit according to claim 1 , wherein the feedback network further comprises an analog-to-digital converter (ADC) connected between the induced voltage detection circuit and the feedback control circuit and configured to convert the feedback signal to a digital signal.
8. The actuator control circuit according to claim 1 , further comprising a digital-to-analog converter (DAC) connected to an input terminal of the drive circuit and an input terminal of the induced voltage detection circuit.
9. The actuator control circuit according to claim 8 , wherein the induced voltage detection circuit comprises:
a replica circuit connected to an output terminal of the DAC; and
a differential amplifier connected to an output terminal of the replica circuit.
10. The actuator control circuit according to claim 1 , wherein the induced voltage detection circuit is further configured to receive information relating to a direction of current though the drive circuit.
11. A method for controlling an actuator, comprising:
supplying a drive signal to the actuator;
detecting an induced voltage generated by the actuator;
generating a feedback signal according to the detected induced voltage;
attenuating a portion of the feedback signal;
adjusting a gain of the feedback signal; and
operating the actuator according to the feedback signal.
12. The method for controlling an actuator according to claim 11 , further comprising: receiving a position signal; and
operating the actuator according to the position signal and the feedback signal.
13. The method for controlling an actuator according to claim 11 , wherein adjusting the gain comprises:
decreasing the gain during a first count period; and
increasing the gain during a second count period.
14. The method for controlling an actuator according to claim 13 , further comprising disabling the feedback signal for a period of time between the first count period and the second count period.
15. An imaging system capable of performing autofocus with an actuator, comprising:
an image signal processor (ISP) configured to generate an initial position signal; and
a camera module connected to the image signal processor, comprising:
an image sensor coupled to the image signal processor, wherein the image sensor transmits image data to the image signal processor; and
a control circuit connected to the ISP and configured to receive the initial position signal from the image signal processor, wherein the control circuit comprises:
a drive circuit connected to the actuator;
a feedback network connected to the drive circuit and configured to generate a feedback signal, wherein the feedback network comprises:
an induced voltage detection circuit connected to an output terminal of the drive circuit; and
a feedback control circuit connected to the induced voltage detection circuit and configured to:
attenuate a portion of the feedback signal that falls outside of a predetermined frequency range; and
adjust a gain of the feedback signal; and
a target generator circuit connected to the ISP and configured to generate an updated position signal according to the initial position signal;
wherein the control circuit supplies a current, based on the feedback signal and the updated position signal, to the actuator.
16. The imaging system according to claim 15 , wherein the feedback control circuit comprises:
a band-pass filter; and
a gain control circuit connected to an output terminal of the band-pass filter.
17. The imaging system according to claim 16 , wherein the gain control circuit comprises:
an amplifier;
a first switch connected between the band-pass filter and an input terminal of the amplifier; and
a second switch connected to an output terminal of the amplifier.
18. The imaging system according to claim 17 , wherein:
the amplifier is configured to adjust the gain of the feedback signal according to a counter value; and
wherein the first and second switches are operated according to the counter value.
19. The imaging system according to claim 15 , wherein the feedback control circuit is further configured to:
decrease the gain of the feedback signal for a first count period; and
increase the gain of the feedback signal for a second count period.
20. The imaging system according to claim 19 , wherein the control circuit is further configured to disable the feedback control circuit for a period of time between the first count period and the second count period.