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

A camera module, comprising:

• a holder comprising a first side wall, the first side wall having a first hole formed therethrough;
• a focus adjustable lens including a common electrode, a first feedback electrode, a plurality of individual electrodes, and a second feedback electrode;
• a voltage control circuit configured to supply a driving voltage to the focus adjustable lens in order to control an interface in the focus adjustable lens, the voltage control circuit configured to supply the driving voltage based on a capacitance between the first feedback electrode and the second feedback electrode in the focus adjustable lens;
• and
• a feedback voltage control circuit transferring a feedback voltage to any one of the first feedback electrode and the second feedback electrode, in order to measure the capacitance between the first feedback electrode and the second feedback electrode,
• wherein the second feedback electrode is disposed between the individual electrodes, and
• wherein the first feedback electrode is disposed at a position corresponding to the second feedback electrode.

A camera module, comprising:

• a holder comprising a first side wall, the first side wall having a first hole formed therethrough;
• a focus adjustable lens disposed in the holder and comprising a common electrode and a plurality of individual electrodes;
• a voltage control circuit configured to supply a driving voltage to the focus adjustable lens in order to control an interface in the focus adjustable lens, the voltage control circuit configured to supply the driving voltage based on a capacitance between the common electrode and at least one individual electrode of the plurality of individual electrodes in the focus adjustable lens;
• a capacitance measuring circuit configured to measure the capacitance between the common electrode and the at least one individual electrode of the plurality of individual electrodes in the focus adjustable lens;
• a first switch located between the capacitance measuring circuit and the focus adjustable lens;
• and
• a second switch located between the voltage control circuit and the first switch and between the voltage control circuit and the focus adjustable lens,
• wherein the capacitance measuring circuit is configured to measure the capacitance between the common electrode and each individual electrode of the plurality of individual electrodes,
• wherein one side of the first switch is electrically connected to the focus adjustable lens and the voltage control circuit,
• wherein the second switch is turned on when a common electrode voltage is supplied to the common electrode, and turned off when the capacitance measuring circuit measures the capacitance,
• wherein, when the common electrode is floating after a ground voltage is supplied to the common electrode after a shape of the interface is changed by the driving voltage, the capacitance is measured during a period when the first switch is turned on and a voltage supplied to the at least one individual electrode is changed from a first voltage to a second voltage having a lower level than the first voltage,
• wherein the first switch is turned off when the voltage control circuit supplies the driving voltage to the focus adjustable lens for operating the focus adjustable lens,
• wherein the voltage control circuit comprises:
• a first voltage control circuit configured to supply a common electrode voltage to the common electrode;
• and
• a second voltage control circuit 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,
• wherein the common electrode voltage and the at least one individual electrode voltage are applied to the common electrode and the individual electrode at different times, respectively,
• wherein the voltage control circuit is configured to generate the driving voltage used for operating the focus adjustable lens as well as to accumulate electric charge used for measuring the capacitance between the common electrode and the at least one individual electrode,
• wherein the capacitance measuring circuit includes a reference capacitor,
• wherein the capacitance between the common electrode and the at least one individual electrode is measured by using the reference capacitor,
• wherein the holder comprises:
• a second side wall opposite the first sidewall in a first direction perpendicular to an optical axis of the camera module;
• and
• a first plate having a cavity in which the focus adjustable lens is disposed, and wherein the second side wall has a second hole formed therethrough.