Control circuit of liquid lens, camera module and method of controlling liquid lens

1. A device for controlling a liquid lens, comprising:

a liquid lens including electrodes;

a voltage control circuit configured to supply a driving voltage to the electrodes in order to control an interface in the liquid lens;

a capacitance measuring circuit configured to measure a capacitance corresponding to the interface; and

a first switch located between the capacitance measuring circuit and the liquid lens,

wherein one side of the first switch is electrically coupled with the liquid lens and the voltage control circuit,

wherein the voltage control circuit is configured to control the driving voltage based on information determined by the capacitance measured by the capacitance measuring circuit.

2. The device according to claim 1 ,

wherein the liquid lens includes a first liquid and a second liquid forming the interface,

wherein the electrodes include a common electrode and a plurality of individual electrodes,

wherein the capacitance measuring circuit is configured to measure the capacitance between the common electrode and an individual electrode.

3. The device according to claim 1 , wherein,

when one of the electrodes is floating after a ground voltage is supplied to the one of the electrodes,

the capacitance is measured during a period when the first switch is turned on and a voltage supplied to at least one of the other electrodes is changed from a first voltage to a second voltage having a lower level than the first voltage.

4. The device according to claim 1 , wherein the first switch is turned off when the voltage control circuit supplies the driving voltage to the electrodes for operating the liquid lens.

5. The device according to claim 1 , wherein the voltage control circuit is configured to generate the driving voltage used for operating the liquid lens as well as to accumulate electric charge used for measuring the capacitance between electrodes.

6. The device according to claim 1 , wherein the capacitance measuring circuit includes a reference capacitor, and

wherein the capacitance between the electrodes is measured by using the reference capacitor.

7. The device according to claim 3 , wherein the second voltage is a ground voltage, and

wherein one of the electrodes is floating during a period when the first switch is turned on.

8. The device according to claim 1 , wherein the capacitance measuring circuit delivers the information determined by the capacitance to the voltage control circuit.

9. The device according to claim 1 , wherein the information determined by the capacitance measured by the capacitance measuring circuit is a value of voltage or a value of capacitance.

10. The device according to claim 1 ,

wherein the driving voltage is created via interaction between the voltage of electrodes.

11. The device according to claim 2 ,

wherein the voltage control circuit includes a first voltage control circuit and a second voltage control circuit,

wherein the first voltage control circuit is configured to supply a common electrode voltage to the common electrode; and

wherein the second voltage control circuit is configured to supply individual electrode voltages to the plurality of individual electrodes, respectively, the driving voltage being created via interaction between the common electrode voltage and at least one individual electrode voltage of the individual electrode voltages.

12. A device for controlling a liquid lens, comprising:

a liquid lens including electrodes;

a voltage control circuit configured to supply a driving voltage to the electrodes in order to control an interface in the liquid lens;

a capacitance measuring circuit configured to measure a capacitance corresponding to the interface; and

a first switch located between the capacitance measuring circuit and the liquid lens,

wherein one side of the first switch is electrically coupled with the liquid lens and the voltage control circuit,

wherein the voltage control circuit is configured to adjust the driving voltage when the capacitance measured by the capacitance measuring circuit is different from a target capacitance.

13. A camera module of claim 12 ,

wherein a capacitance between one of the electrodes and each of the others is sequentially measured by the capacitance measuring circuit.

14. A camera module, comprising:

an image sensor;

a lens assembly on the image sensor, the lens assembly including a liquid lens and at least one solid lens, and the liquid lens including electrodes;

a voltage control circuit configured to supply a driving voltage into the liquid lens in order to control an interface in the liquid lens;

a capacitance measuring circuit configured to measure a capacitance corresponding to the interface; and

a first switch located between the capacitance measuring circuit and the liquid lens,

wherein one side of the first switch is electrically coupled with the liquid lens and the voltage control circuit,

wherein the liquid lens includes a second plate, a third plate, and a first plate disposed between the second plate and the third plate,

wherein the first plate includes a cavity comprising a conductive liquid and a non-conductive liquid,

wherein one of the electrodes is located between the first plate and the third plate, and another electrode is located between the first plate the second plate.