Liquid lens control systems and methods
Control systems for liquid lenses can use feedback control using one or more measured parameters indicative of a position of the fluid interface in the liquid lens. Capacitance between a fluid and an electrode in the liquid lens can vary depending on the position of the fluid interface. Current mirrors can be used for making measurements indicative of the capacitance and/or the fluid interface position. The liquid lens can be calibrated using the measurements indicative of capacitance and/or fluid interface position as the voltage is driven across an operational range. A control system can use pulse width modulation (PWM) for driving a liquid lens, and a carrier frequency for the PWM signals can be varied to control power consumption in the liquid lens. The slew rate can be adjustable to control power consumption in the liquid lens.
1. A liquid lens camera system comprising:
an imaging sensor, wherein the camera system is configured to use the imaging sensor to produce images having a first image setting and to produce images having a second image setting, wherein the second image setting has a lower image resolution than the first image setting;
a liquid lens comprising:
a chamber;
a first fluid contained in the chamber;
a second fluid contained in the chamber, wherein the first fluid and the second fluid are substantially immiscible to form a fluid interface between the first fluid and the second fluid;
a first electrode insulated from the first and second fluids; and
a second electrode in electrical communication with the first fluid, wherein the liquid lens is configured such that a position of the fluid interface is based at least in part on voltages applied between the first electrode and the second electrode;
a signal generator configured to apply voltages between the first electrode and the second electrode using pulse width modulation (PWM); and
a controller configured to:
receive a first indication to produce one or more images having the first image setting;
in response to the first image setting, apply a first PWM switching frequency to the liquid lens for the one or more images;
receive a second indication to produce one or more images having the second image setting; and
in response to the second image setting, apply a second PWM switching frequency to the liquid lens for the one or more images having the second image setting, wherein the second PWM switching frequency is slower than the first PWM switching frequency.
2. The liquid lens camera system of claim 1 , wherein the first image setting comprises a first resolution, and wherein the second image setting comprises a second resolution that is lower than the first resolution.
3. The liquid lens camera system of claim 1 , wherein the first image setting comprises enabled optical image stabilization, and wherein the second setting comprises disabled optical image stabilization.
4. The liquid lens camera system of claim 1 , wherein the first PWM switching frequency is between 5 kHz and 50 kHz, and wherein the second PWM switching frequency is between 0.5 kHz and 5 kHz.
5. The liquid lens camera system of claim 1 , wherein the controller is configured to:
apply a first slew rate to the liquid lens using the signal generator for the one or more images having the first image setting; and
apply a second slew rate to the liquid lens using the signal generator for the one or more images having the second image setting, wherein the second slew rate is lower than the first slew rate.
6. A mobile electronic device comprising:
the liquid lens camera system of claim 1 ; and
a battery configured to power the mobile electronic device including powering the liquid lens camera system;
wherein the mobile electronic device has a low power consumption mode of operation, and wherein the controller receives the second indication to produce the one or more images having the second image setting when the mobile electronic device is in low power consumption mode.
7. The mobile electronic device of claim 6 , wherein:
the mobile electronic device is configured to run a first application that uses the liquid lens camera system to produce the one or more images having the first image setting;
the mobile electronic device is configured to run a second application that uses the liquid lens camera system to produce the one or more images having the second image setting; and
the controller applies the first PWM switching frequency for the first application and the second PWM switching frequency for the second application.
8. A liquid lens system comprising:
a liquid lens;
a signal generator configured to apply voltage pulses to the liquid lens at a carrier frequency; and
a controller configured to:
receive an indication to produce one or more images;
identify a plurality of image parameters comprising an image resolution for the one or more images; and
vary the carrier frequency of the voltage pulses applied to the liquid lens in response to the image resolution.
9. The liquid lens system of claim 8 , wherein the liquid lens comprises:
a chamber;
a first fluid contained in the chamber;
a second fluid contained in the chamber, wherein the first fluid and the second fluid are substantially immiscible to form a fluid interface between the first fluid and the second fluid;
a first electrode insulated from the first and second fluids; and
a second electrode in electrical communication with the first fluid, wherein the liquid lens is configured such that a position of the fluid interface is based at least in part on voltages applied between the first electrode and the second electrode.
10. The liquid lens system of claim 8 , wherein the signal generator is configured to use pulse width modulation (PWM) to apply voltages to the liquid lens.
11. The liquid lens system of claim 8 , wherein the controller is configured to:
receive a first indication of a first image parameter of the plurality of image parameters;
apply a first carrier frequency to the liquid lens in response to the first image parameter;
receive a second indication of a second image parameter of the plurality of image parameters; and
apply a second carrier frequency that is different than the first carrier frequency to the liquid in response to the second image parameter.
12. The liquid lens system of claim 11 , wherein the second carrier frequency is lower than the first carrier frequency.
13. The liquid lens system of claim 11 , wherein the second image parameter has a lower-quality image setting than the first image parameter.
14. The liquid lens system of claim 11 , wherein:
the first image parameter comprises a first resolution and the first carrier frequency is applied in response to the first resolution; and
the second image parameter comprises a second resolution and the second carrier frequency is applied in response to the second resolution.
15. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on the image resolution.
16. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on an indication of a video or still image.
17. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on an indication of a preview image or captured image.
18. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on whether optical image stabilization is enabled or disabled.
19. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on an indication of an application used to request an image.
20. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on battery capacity.
21. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on whether a low power consumption mode is enabled or disabled.
22. The liquid lens system of claim 8 , wherein the controller is configured to vary the carrier frequency of the voltage pulses applied to the liquid lens based at least in part on whether an external power supply is supplying power.
23. The liquid lens system of claim 8 , wherein the controller is configured to vary a slew rate for the voltage pulses applied to the liquid lens using the signal generator.
24. The liquid lens system of claim 23 , wherein a faster slew rate is applied to a faster carrier frequency, and wherein a slower slew rate is applied to a slower carrier frequency.
25. The liquid lens system of claim 8 , further comprising a camera module that comprises:
one or more fixed lenses; and
an imaging sensor.
26. A mobile electronic device comprising the liquid lens system of claim 8 .