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

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 a common electrode and a plurality of individual 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 between the common electrode and the plurality of individual electrodes in the liquid lens;
• 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 the common electrode is located between the first plate and the third plate, and the plurality of individual electrodes are located between the first plate the second plate, and
• wherein the capacitance between the common electrode and the plurality of individual electrodes in the liquid lens includes a plurality of capacitances sequentially measured between the common electrode and each individual electrode of the plurality of individual electrodes.

A method for controlling a liquid lens, the method comprising:

• supplying a ground voltage to a common electrode of the liquid lens and an individual electrode voltage to at least one individual electrode of a plurality individual electrodes of the liquid lens to accumulate electric charge between the common electrode and the at least one individual electrode of the plurality of individual electrodes;
• floating the common electrode of the liquid lens;
• turning on a first switch located between the liquid lens and a capacitance measuring circuit;
• measuring a reference voltage between both sides of a reference capacitor in the capacitance measuring circuit;
• measuring a capacitance between the common electrode and the at least one individual electrode of the plurality of individual electrodes by using the reference voltage;
• and
• controlling a driving voltage based on the information determined by the measured capacitance,
• wherein the capacitance includes a plurality of capacitances sequentially measured between the common electrode and each individual electrode of the plurality of individual electrodes.