KR102140280B1 - Control circuit of liquid lens, camera module and controlling method for liquid lens - Google Patents

Abstract

In the liquid lens control method according to the embodiment, the common electrode of the liquid lens is grounded, and a voltage is applied to any one of a plurality of individual electrodes of the liquid lens, and a voltage is not applied to the common electrode of the liquid lens. Step of blocking, electrically connecting the capacitive measuring circuit and the liquid lens, measuring the voltage across the capacitor of the capacitive measuring circuit, and controlling the driving voltage using the measured voltage across the capacitor. Steps.

Description

Liquid lens control circuit, camera module and liquid lens control method {CONTROL CIRCUIT OF LIQUID LENS, CAMERA MODULE AND CONTROLLING METHOD FOR LIQUID LENS}

The present invention relates to a liquid lens and a camera module and optical device including the same. More specifically, the present invention relates to a camera module and an optical device including a control module or control device for controlling a liquid lens capable of adjusting a focal length using electric energy.

Users of portable devices have high resolution, small size and various shooting functions (e.g. optical zoom function (zoom-in/zoom-out), auto-focusing (AF) function), image stabilization or image stabilization (Optical Image) Stabilizer, OIS) function, etc.). Such a photographing function may be implemented through a method of directly moving a lens by combining several lenses, but if the number of lenses is increased, the size of the optical device may be increased. The auto focus and image stabilization functions are performed by moving or tilting multiple lens modules fixed to the lens holder and aligned with the optical axis in the vertical direction of the optical axis or optical axis, and driving a separate lens to drive the lens module The device is used. However, the lens driving device has high power consumption, and in order to protect it, a cover glass must be added separately from the camera module, so the overall thickness becomes thicker. Accordingly, research is being conducted on a liquid lens that performs autofocus and image stabilization functions by electrically controlling the curvatures of the interfaces of the two liquids.

The present invention provides a feedback circuit capable of recognizing a state of an interface included in a liquid lens through a change in capacitance in a camera device including a liquid lens capable of adjusting a focal length using electric energy. Correspondingly, the movement of the interface of the liquid lens can be more accurately recognized, and the interface of the liquid lens can be more accurately controlled.

In addition, the present invention is a capacitor having a very small capacitance (eg, 200 ~ 500pF or less), but a very high voltage (eg, 30 ~ 50V or more) is supplied to both ends, a feedback circuit capable of measuring a change in capacitance Can provide.

In addition, in the present invention, the common electrode is a ground voltage and the individual electrodes fall from a high voltage (eg, 10 to 50 V or more) to a ground voltage so as to measure the capacitance between the electrodes disposed on the liquid lens that can adjust the focal length. It is possible to provide an apparatus and method for measuring capacitance by floating a common electrode at a falling edge.

In addition, the present invention does not recognize the motion and shape of the interface of the liquid lens capable of adjusting the focal length by converting the optical signal passing through the interface into an image, and directly recognizes the motion and shape of the interface through a change in the capacitance of the interface. By doing so, it is possible to more accurately control the performance and operation of the liquid lens.

In addition, the present invention is capable of recognizing the movement and shape of the interface in the liquid lens, thereby correcting lens distortion or controlling a lens assembly in a lens assembly including a liquid lens and a solid lens. Can provide.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present invention belongs from the following description. Will be able to.

The control circuit of a liquid lens according to an embodiment of the present invention includes a liquid lens including a plurality of individual electrodes and a common electrode; A voltage control circuit that supplies a voltage to the liquid lens to control the interface of the liquid lens; And a capacitance measurement circuit for calculating a capacitance between the common electrode of the liquid lens and the plurality of individual electrodes. A first switch is disposed between the capacitive measurement circuit and the liquid lens, and one end of the first switch may be electrically connected to the liquid lens and the voltage control circuit.

In addition, the capacitive measurement circuit includes a reference capacitor, and the capacitance of the liquid lens may be calculated using the reference capacitor.

In addition, the other end of the first switch may be connected to the capacitance measurement circuit.

In addition, the capacitance measurement circuit may be connected to the common electrode.

Further, the capacitance measurement circuit may be connected to at least one individual electrode among the plurality of individual electrodes.

In addition, the voltage control circuit may include a first voltage control circuit that supplies voltage to the common electrode and a second voltage control circuit that supplies voltage to the plurality of individual electrodes.

In addition, the first voltage control circuit may include a second switch for applying ground to the common electrode.

Further, the common electrode may be floated to measure the capacitance.

In addition, information calculated by the capacitance measurement circuit may be transferred to the voltage control circuit, and the voltage control circuit may adjust the driving voltage using the calculated information.

Also, the information calculated by the capacitance measurement circuit may be a voltage or a capacitance value.

Also, the common electrode may be floated during the period in which the first switch is turned on.

In addition, the liquid lens control circuit further includes a third switch disposed between the voltage control circuit and the first switch and between the voltage control circuit and the liquid lens, and the third switch supplies voltage to the common electrode. While on, and the capacitance measurement circuit can be turned off while measuring the capacitance.

A camera module according to another embodiment of the present invention includes a liquid lens including a plurality of individual electrodes and a common electrode; A voltage control circuit that supplies a voltage to the liquid lens to control the interface of the liquid lens; And a capacitance measurement circuit for calculating a capacitance between the common electrode of the liquid lens and the plurality of individual electrodes. A first switch disposed between the capacitive measurement circuit and the liquid lens; A lens assembly including at least one solid lens disposed above or below the liquid lens; And an image sensor disposed under the lens assembly, wherein one end of the first switch is electrically connected to the liquid lens and the voltage control circuit, and the liquid lens has a cavity in which conductive liquid and non-conductive liquid are disposed. A first plate comprising; A second plate disposed on the first plate; And a third plate disposed under the first plate, wherein the common electrode is disposed on the first plate, and the plurality of individual electrodes can be disposed under the first plate.

According to another embodiment of the present invention, a method for controlling a liquid lens includes connecting a common electrode of a liquid lens to ground, applying a voltage to individual electrodes of the liquid lens, and accumulating charge between the common electrode and individual electrodes; Turning on a first switch disposed between the capacitive measurement circuit and the liquid lens; Measuring a voltage across a reference capacitor of the capacitance measurement circuit; And calculating a capacitance between the common electrode and individual electrodes by using the measured value of the voltage across the reference capacitor.

In addition, the liquid lens control method may further include the step of moving at least a portion of the accumulated charge to the reference capacitor.

In addition, the liquid lens control method includes the step of turning on the first switch and measuring the voltage across the reference capacitor of the capacitance measurement circuit, at least a portion of the accumulated charge moves to the reference capacitor. It may further include a step.

The above aspects of the present invention are only some of the preferred embodiments of the present invention, and various embodiments in which the technical features of the present invention are reflected are detailed description of the present invention, which will be described below by those skilled in the art. It can be derived and understood based on.

When explaining the effect on the device according to the present invention as follows.

The present invention can provide a method and apparatus that can more accurately measure the movement and change of the interface.

In addition, the present invention can accurately measure the movement and shape of the interface in the liquid lens, and can perform more efficient optical stabilization on the image or image obtained by converting the optical signal transmitted through the liquid lens.

In addition, the present invention can recognize the movement and shape of the interface in the liquid lens, thereby improving the quality of an image obtained through a camera device or an optical device including a lens assembly including a liquid lens and a solid lens.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 illustrates an example of a camera device.
2 illustrates an example of a lens assembly included in a camera device.
3 illustrates a liquid lens whose focal length is adjusted in response to a driving voltage.
4 illustrates the structure of a liquid lens.
5 illustrates changes in the interface in the liquid lens.
6 describes a control circuit interlocking with the liquid lens.
7 illustrates an example of a capacitance measurement circuit.
8 explains a first example of the control circuit.
Fig. 9 explains the operation of the control circuit of Fig. 8;
10 illustrates a second example of the control circuit.
Fig. 11 explains the operation of the control circuit of Fig. 10;
Fig. 12 explains the connection of the liquid lens and the control circuit.
13 illustrates the timing of the switching elements shown in FIG. 12 for measuring the capacitance of a liquid lens.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The embodiment may be variously changed and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, it is not intended to limit the embodiment to a specific disclosure form, it should be understood that it includes all modifications, equivalents, or substitutes included in the spirit and scope of the embodiment.

The terms "first", "second", etc. can be used to describe various components, but the components should not be limited by the terms. The terms are used to distinguish one component from other components. In addition, terms specifically defined in consideration of the configuration and operation of the embodiments are only for describing the embodiments and do not limit the scope of the embodiments.

In the description of the embodiment, when described as being formed on the "top (top)" or "bottom (bottom) (on or under)" of each element, the top (top) or bottom (bottom) (on or under) ) Includes both two elements directly contacting each other or one or more other elements formed indirectly between the two elements. In addition, when expressed as “up (up)” or “down (down)” (on or under), it may include the meaning of the downward direction as well as the upward direction based on one element.

In addition, relational terms, such as "top/top/top" and "bottom/bottom/bottom" as used hereinafter, do not necessarily require or imply any physical or logical relationship or order between such entities or elements, It can also be used to distinguish one entity or element from another.

1 illustrates an example of a camera device. As shown, the camera module can include a lens assembly 22 and an image sensor. At least one solid lens may be disposed above or below the lens assembly. The lens assembly 22 may include a liquid lens whose focal length is adjusted in response to an applied voltage. The camera module includes a lens assembly 22 including a plurality of lenses including a first lens whose focal length is adjusted in response to a driving voltage applied between a common terminal and a plurality of individual terminals, and a driving voltage to the first lens. It may include a control circuit 24 for supply, and an image sensor 26 arranged in the lens assembly 22 and converting light transmitted through the lens assembly 22 into an electrical signal and disposed under the lens assembly. have.

Referring to FIG. 1, the camera module may include circuits 24 and 26 formed on one printed circuit board (PCB) and a lens assembly 22 including a plurality of lenses, but this is only one example. It does not limit the scope of the invention. The configuration of the control circuit 24 may be designed differently according to specifications required for the camera module. In particular, when the magnitude of the voltage applied to the liquid lens 28 is reduced, the control circuit 24 may be implemented as a single chip. Through this, the size of the camera module mounted on the portable device can be further reduced.

Referring to FIG. 2, as shown, the lens assembly 22 includes a first lens unit 100, a second lens unit 200, a liquid lens unit 300, a lens holder 400, and a connection unit 500 It may include. The connection part 500 electrically connects the image sensor and the liquid lens, and may include a substrate, a wire, or a wire to be described later. The structure of the illustrated lens assembly 22 is only one example, and the structure of the lens assembly 22 may be changed according to specifications required for the camera module. For example, in the illustrated example, the liquid lens unit 300 is positioned between the first lens unit 100 and the second lens unit 200, but in another example, the liquid lens unit 300 includes the first lens unit ( 100) may be positioned above (front), and one of the first lens unit 100 or the second lens unit 200 may be omitted. The configuration of the control circuit 24 may be designed differently according to specifications required for the camera device. In particular, when the magnitude of the operating voltage applied to the lens assembly 22 is reduced, the control circuit 24 may be implemented as a single chip. Through this, the size of the camera device mounted on the portable device can be further reduced.

2 illustrates an example of a lens assembly 22 included in a camera device.

As illustrated, the lens assembly 22 may include a first lens unit 100, a second lens unit 200, a liquid lens unit 300, a lens holder 400, and a connection unit 500. The connection part 500 electrically connects the image sensor and the liquid lens, and may include a substrate, a wire, or a wire to be described later. The structure of the illustrated lens assembly 22 is only one example, and the structure of the lens assembly 22 may be changed according to specifications required for the camera module. For example, in the illustrated example, the liquid lens unit 300 is positioned between the first lens unit 100 and the second lens unit 200, but in another example, the liquid lens unit 300 includes the first lens unit ( 100) may be positioned above (front), and one of the first lens unit 100 or the second lens unit 200 may be omitted.

Referring to FIG. 2, the first lens unit 100 is disposed in front of the lens assembly, and is a portion where light enters from the outside of the lens assembly. The first lens unit 100 may be provided with at least one lens, or two or more lenses may be aligned with respect to the central axis PL to form an optical system.

The first lens unit 100 and the second lens unit 200 may be mounted on the lens holder 400. In this case, a through hole is formed in the lens holder 400, and the first lens unit 100 and the second lens unit 200 may be disposed in the through hole. In addition, the liquid lens unit 300 may be inserted into a space between the first lens unit 100 and the second lens unit 200 in the lens holder 400.

Meanwhile, the first lens unit 100 may include a solid lens 110. The solid lens 110 may protrude out of the lens holder 400 and be exposed to the outside. When the solid lens is exposed, the lens surface may be damaged due to exposure to the outside. If the lens surface is damaged, the image quality of the image taken by the camera module may deteriorate. In order to prevent and suppress the surface damage of the solid lens 110, a method of arranging a cover glass, forming a coating layer, or configuring the solid lens 100 with a wear-resistant material for preventing surface damage may be applied.

The second lens unit 200 is disposed behind the first lens unit 100 and the liquid lens unit 300, and light incident from the outside to the first lens unit 100 passes through the liquid lens unit 300. Thus, the second lens unit 200 may be incident. The second lens unit 200 is spaced apart from the first lens unit 100 and may be disposed in a through hole formed in the lens holder 400.

Meanwhile, the second lens unit 200 may be provided with at least one lens, and when two or more lenses are included, an optical system may be formed by aligning them with respect to the central axis PL.

The liquid lens unit 300 is disposed between the first lens unit 100 and the second lens unit 200 and may be inserted into the insertion hole 410 of the lens holder 400. The insertion hole 410 may be formed by opening a part of the side surface of the lens holder. That is, the liquid lens may be inserted and disposed through the insertion hole 410 on the side of the holder. The liquid lens unit 300 may also be aligned with respect to the central axis PL, like the first lens unit 100 and the second lens unit 200.

The liquid lens unit 300 may include a lens region 310. The lens region 310 is a portion through which light passing through the first lens unit 100 passes, and may include liquid in at least a portion. For example, the lens region 310 may include two types, that is, a conductive liquid and a non-conductive liquid, and the conductive liquid and the non-conductive liquid may form an interface without mixing with each other. The interface between the conductive liquid and the non-conductive liquid is deformed by the driving voltage applied through the connection part 500 to change the curvature of the interface of the liquid lens 28 or the focal length of the liquid lens. When the deformation and curvature change of the interface is controlled, the liquid lens unit 300 and a camera module including the same may perform an autofocusing function, a camera shake correction function, and the like.

3 illustrates a liquid lens whose focal length is adjusted in response to a driving voltage. Specifically, (a) describes the first lens 28 included in the lens assembly 22 (see FIG. 2), and (b) describes the equivalent circuit of the lens 28.

First, referring to (a), the lens 28 whose focal length is adjusted in response to the driving voltage has voltages through the individual terminals L1, L2, L3, and L4 arranged in four different directions with the same angular distance. Can be accredited. The individual terminals may be arranged with the same angular distance with respect to the central axis of the liquid lens, and may include four individual terminals. The four individual terminals may be respectively disposed at four corners of the liquid lens. When a voltage is applied through the individual terminals L1, L2, L3, and L4, the applied voltage is disposed in the lens region 310 by a driving voltage formed by interaction with a voltage applied to the common terminal C0, which will be described later. The interface between the conductive liquid and the non-conductive liquid may be deformed.

Further, referring to (b), the lens 28 has one side applied with operating voltages from different individual terminals L1, L2, L3, and L4, and the other side has a plurality of capacitors connected to the common terminal C0 ( 30). Here, the plurality of capacitors 30 included in the equivalent circuit may have a small capacitance of about tens to 200 picofarads (pF) or less. The terminal of the above-mentioned liquid lens of the liquid lens may also be referred to herein as an electrode sector or sub-electrode.

4 illustrates the structure of a liquid lens.

As shown, the liquid lens 28 can include a liquid, a first plate and an electrode. The liquids 122 and 124 included in the liquid lens 28 may include conductive liquids and non-conductive liquids. The first plate may include a cavity (150) or a hole in which a conductive liquid and a non-conductive liquid are disposed. The cavity 150 may include an inclined surface. The electrodes 132 and 134 may be disposed on the first plate 114 and may be disposed above the first plate 114 or below the first plate 114. The liquid lens 28 may further include a second plate 112 that may be disposed on the upper (lower) side of the electrodes 132 and 134. In addition, the liquid lens 28 may further include a third plate 116 that may be disposed under (upper) the electrodes 132 and 134. As shown, one embodiment of the liquid lens 28 may include an interface 130 formed by two different liquids 122 and 124. In addition, it may include at least one substrate (142, 144) for supplying a voltage to the liquid lens (28). The edge (corner) of the liquid lens 28 may be thinner than the center of the liquid lens 28. The second plate may be disposed on the upper surface of the liquid lens, and the third plate may be disposed on the lower surface of the liquid lens. However, the second plate or the third plate is not disposed on a portion of the upper or lower surface of the liquid lens corner. May be thinner than the center. The electrode may be exposed on the upper or lower corner of the liquid lens.

The liquid lens 28 includes two different liquids, for example, a conductive liquid 122 and a non-conductive liquid 124, and the curvature and shape of the interface 130 formed by the two liquids are in the liquid lens 28. It can be adjusted by the supplied driving voltage. The driving voltage supplied to the liquid lens 28 may be transmitted through the connection part 500. The connection part may include at least one of the first substrate 142 and the second substrate 144. When the connection portion includes the first substrate 142 and the second substrate 144, the second substrate 144 may transmit voltage to each of a plurality of individual terminals, and the first substrate 142 applies a voltage to the common terminal. Can deliver. The plurality of individual terminals may be four, and the second substrate 144 may transfer voltage to each of the four individual terminals. The voltage supplied through the second substrate 144 and the first substrate 142 may be applied to the plurality of electrodes 134 and 132 disposed or exposed at each corner of the liquid lens 28.

In addition, the liquid lens 28 is located between the third plate 116 and the second plate 112, the third plate 116 and the second plate 112 including a transparent material, and has a predetermined inclined surface A first plate 114 including an area may be included.

In addition, the liquid lens 28 may include a cavity 150 determined by the third plate 116, the second plate 112, and the opening areas of the first plate 114. Here, the cavity 150 may be filled with two liquids 122 and 124 of different properties (eg, conductive liquid and non-conductive liquid), and an interface 130 between the two liquids 122 and 124 of different properties ) May be formed.

Further, at least one of the two liquids 122 and 124 included in the liquid lens 28 has conductivity, and the liquid lens 28 has two electrodes 132 and 134 disposed above and below the first plate 114. It may include. The first plate 114 may include an inclined surface and further include an insulating layer 118 disposed on the inclined surface. The liquid having conductivity may contact the insulating layer. Here, the insulating layer 118 covers one electrode (eg, the second electrode 134) of the two electrodes 132 and 134, and covers a part of the other electrode (eg, the first electrode 132). Alternatively, it can be exposed to allow electrical energy to be applied to the conductive liquid (eg, 122). Here, the first electrode 132 includes at least one electrode sector (eg, C0), and the second electrode 134 includes two or more electrode sectors (eg, L1, L2, L3, L4 in FIG. 4). can do. For example, the second electrode 134 may include a plurality of electrode sectors sequentially arranged along the optical axis in a clockwise direction. The electrode sector may be referred to as a sub-electrode or terminal of a liquid lens.

One or two or more substrates 142 and 144 for transmitting a voltage to the two electrodes 132 and 134 included in the liquid lens 28 may be connected. The focal length of the liquid lens 28 may be adjusted while the curvature, curvature, or inclination of the interface 130 formed in the liquid lens 28 changes in response to the driving voltage.

5 illustrates changes in the interface in the liquid lens. Specifically, (a) to (c) describe the movement of the interfaces 30a, 30b, 30c that may occur when a voltage is applied to the individual electrodes L1, L2, L3, L4 of the liquid lens 28. .

First, referring to (a), when substantially the same voltage is applied to the individual electrodes L1, L2, L3, and L4 of the liquid lens 28, the interface 30a may maintain a shape close to a circle. When viewed from the upper surface, the horizontal distance (LH) of the interface and the vertical distance (LV) of the interface are substantially the same, and the movement (eg, inclination angle) of the interface 30a may have a balanced shape. In this case, the capacitance values of the interface 30a measured through the four different individual electrodes L1, L2, L3, and L4 can be measured substantially the same.

Also, referring to (b), the voltage applied to the first individual electrode L1 and the third individual electrode L3 of the liquid lens 28 is applied to the second individual electrode L2 and the fourth individual electrode L4. The case higher than the applied voltage will be described. In this case, since the force of pulling or pushing the interface 30b is different in horizontal or vertical, the horizontal distance (LH) of the interface when viewed from the upper surface may be shorter than the vertical distance (LV) of the interface when viewed from the upper surface. . When the voltage applied to the second individual electrode L2 and the fourth individual electrode L4 is lower than that of the first individual electrode L1 and the third individual electrode L3, the second individual electrode L2 and the fourth electrode The inclination angle of the interface 30b of the liquid lens 28 at the individual electrode L4 is greater than the inclination angle of the interface 30b of the liquid lens 28 at the first individual electrode L1 and the third individual electrode L3. Because it is small, it looks the same on a plane, but in three dimensions the vertical distance (LV) is longer than the horizontal distance (LH). In this case, the capacitance values of the interfaces 30a measured through four different individual electrodes L1, L2, L3, and L4 may be different. On the other hand, since the interface 30b is symmetrically changed at the interface 30b, the capacitance value of the interface 30a measured through four different individual electrodes L1, L2, L3, and L4 may be symmetrical. In this case, the capacitance values of L1 and L3 are the same, and the capacitance values of L2 and L4 may be the same.

Further, referring to (c), the voltage applied to the first individual electrode L1 and the third individual electrode L3 of the liquid lens 28 and the second individual electrode L2 and the fourth individual electrode L4 Since the voltage applied to is changed, the vertical distance (LV) of the interface of the interface may be shorter than the horizontal distance (LH) when viewed from the top. As in the case of (b), the capacitance of the interface 30c measured through the four different individual electrodes L1, L2, L3, and L4 may be different. On the other hand, since the interface 30c has a symmetrical change in the interface 30b, the capacitance values of the interface 30a measured through four different individual electrodes L1, L2, L3, and L4 may be symmetrical. In this case, the capacitance values of L1 and L3 are the same, and the capacitance values of L2 and L4 may be the same.

In addition, the capacitances measured at the interfaces 30a, 30b, and 30c shown in (a), (b), and (c) are different, and the first individual electrodes L1 to 4th individual through the difference in the capacitances Depending on the voltage applied to the electrode L4, it can be more directly and accurately measured how the interfaces 30a, 30b, and 30c have moved differently than before.

Meanwhile, in the above-described example, the structure in which the liquid lens 28 includes four individual electrodes has been described, but the liquid lens 28 has more individual electrodes such as eight, twelve, sixteen, and the like. When the feedback electrode is included, the movement of the liquid lens 28 can be more precisely controlled, and the movement can be more accurately measured.

6 describes a control circuit interlocking with the liquid lens.

As shown, the liquid lens 28 includes four individual electrodes L1, L2, L3, L4 and one common electrode C0 (see Fig. 3). The voltage control circuit 40 may generate and supply the voltages VL1, VL2, VL3, VL4, and VC0 applied to the four individual electrodes L1, L2, L3, and L4 and one common electrode C0. For example, referring to FIGS. 4 and 5, four individual electrodes L1, L2, L3, and L4 may correspond to the second electrode 134, and one common electrode C0 may be the first electrode ( 132).

The capacitive measurement circuit 50 is for measuring or calculating the position, shape or movement of the interface 30 in the liquid lens 28. The position, shape, or movement of the liquid lens 28 interface 30 can be measured using capacitance (capacitance) as described in FIG. 3. To measure the capacitance between the first electrode and the second electrode of the liquid lens 28, at least one individual electrode (L1, L2, L3, L4) and a common electrode included in the liquid lens 28 can be used. .

The voltage control circuit 40 connects the voltages (VL1, VL2, VL3, VL4, VC0) at a level of at least 0 V to 80 V to the four individual electrodes L1, L2, L3, L4 and the common electrode C0. Or, it can be provided at another time. The voltage control circuit 40 does not apply voltages to the four individual electrodes L1, L2, L3, L4 and the common electrode C0 at the same time, and the voltage control circuit 40 or a separate control unit (not shown) ) Can be delivered in response to the generated timing.

As shown, the liquid lens 28 interface 30 has a plurality of individual electrodes (L1, L2, L3, L4) and the voltage (VL1, VL2, VL3, VL4, VC0) transmitted to the common electrode (C0) It can be controlled in response to the driving voltage to be formed. The change in the movement, position, or shape of the interface 30 in the liquid lens 28 is the voltage of the first to fourth voltages VL1, VL2, VL3, and VL4 and the voltage VC0 applied to the common electrode C0. It can be caused by tea.

Changes in the movement, position, or shape of the interface 30 in the liquid lens 28 due to a voltage difference between the first to fourth voltages VL1, VL2, VL3, and VL4 and the voltage VC0 of the common electrode C0. When occurs, a change in capacitance may occur. Movement of the interface 30 in the liquid lens 28. The change in capacitance caused by a change in position or shape may range from a few pF to tens of pF.

The position or shape of the interface 30 by the voltage applied to the first to fourth individual electrodes L1, L2, L3, L4 is common after the ground voltage GND, 0V is applied to the common electrode C0. It can be measured by floating the electrode (C0). More specifically, the first to fourth voltages VL1, VL2, VL3, which float the common electrode C0 and are applied to one of the first to fourth individual electrodes L1, L2, L3, and L4, When VL4) is a falling edge or a rising edge falling from a high voltage (eg, 10 to 80 V) to a ground voltage (0 V), capacitance can be measured using a change in voltage applied to the corresponding electrode. (Measurement of ground floating edge)

The capacitive measurement circuit 50 connected to the common electrode C0 side in the liquid lens 28 may measure the capacitance between the individual electrode and the common electrode in the liquid lens 28. Depending on the embodiment, the capacitive measurement circuit 54 may include various components.

For example, the capacitive measurement circuit 54 for measuring a small capacitance change of a few pF to tens of pF does not measure the capacitance of any absolute value, but rather measures one or both of the two capacitors that already know the value. It is possible to measure the change in capacitance through a differential comparison that measures capacitance through the difference in the amount of physical change that occurs when exposed to external changes.

As another example, the capacitive measurement circuit 54 for measuring a small capacitance of several pF to tens of pF calculates the ratio between a capacitor having a known large value and a capacitor having a small value to be measured and finds the value. It is also possible to measure the capacitance of the interface 30 through the way out.

The capacitance measurement circuit 50 transmits the calculated or measured information to the voltage control circuit 40, and the voltage control circuit 40 can adjust the voltages VL1, VL2, VL3, VL4, and VC0 in response to the information. have. The information calculated or measured by the capacitive measurement circuit may be a voltage or a capacitance value. The liquid lens control circuit that transmits the information calculated by the capacitance measurement circuit to the voltage control circuit and adjusts the driving voltage using the calculated information may be configured.

7 illustrates an example of a capacitance measurement circuit. The capacitive measurement circuit shown in FIG. 8 is presented as an example, and may include various components according to embodiments.

As illustrated, when the voltage transmitted from the voltage control circuit 40 is applied to one of the electrodes L1 disposed on the liquid lens, the capacitance measurement circuit 54 connected to the other (C0) is connected to the two electrodes L1. , C0) by measuring the capacitance between the interface 30 can be recognized.

When the voltage VL1 is applied and the first switch SW1 in the voltage control circuit 40 is connected, the amount of charge Q at the interface 30 is the capacitance C of the interface 30 at the change amount ΔVL1 of the voltage ). When the first switch SW1 is connected, the charge Q may move to the reference capacitor Cap-m.

Thereafter, when the first switch SW1 is turned OFF and the second switch SW1 is turned ON at a falling edge where the voltage VL1 falls to the ground voltage, the reference capacitor Cap-m The charges transferred to can move to the on-chip capacitor (Cap-on). At this time, the amount of charge Q moving to the on-chip capacitor Cap-on may be equal to the amount of change in the feedback voltage ΔVL1 multiplied by the capacitance of the on-chip capacitor Cap-on.

Adjust the ratio of the number of couplings by the capacitance C of the interface 30 and the number of couplings by the on-chip capacitor (Cap-on) so that the total amount of charges accumulated in the reference capacitor (Cap-m) is 0. The ratio of the two capacitances is calculated from the ratio. Since the capacitance of the on-chip capacitor (Cap-on) is a known value, it is possible to measure the capacitance of the capacitance (C) of the interface (30).

The configuration of the above-described capacitive measurement circuit 54 may vary depending on the embodiment, and thus the operation and control method may be different. Here, the capacitive measurement circuit 54 may be designed to measure a change of several pF to 200 pF.

The circuit configuration for measuring the capacitance may be implemented in various ways depending on the embodiment. For example, a circuit for calculating capacitance based on a resonance frequency using LC series resonance for a common electrode may be used. However, in the case of using LC series resonance, since it is necessary to apply a waveform for each frequency in order to find the resonance frequency, it may take time to calculate the capacitance, and this may affect the interface of the liquid lens. However, the above-described capacitance measurement circuit 54 is a capacitance measurement circuit using a switched capacitor. The switched capacitor may include two switches and one capacitor, which is a device for controlling the average current flowing therethrough, and the average resistance is inversely proportional to the capacitor capacity and the switch operating frequency. When the capacitance of a liquid lens is measured using a switched capacitor, the capacitance can be measured at a very high speed (eg, tens of ns).

In addition, as a circuit for measuring capacitance, a switched capacitor circuit that can be composed of only a capacitor and a switch has a higher directivity than an LC series resonant circuit that must include resistors, inductors, and capacitors, so it can be easily applied to mobile devices and the like. . One end of the first switch may be electrically connected to the liquid lens and the voltage control circuit.

8 explains a first example of the control circuit. For convenience of description, one of the plurality of individual electrodes L1 will be described as an example.

As shown, the control circuit includes a voltage control circuit 40 and a capacitive measurement circuit 50 and can be connected to the liquid lens 28. The voltage control circuit 40 may selectively transfer one of the high voltage (eg, 70V, 35V) and the ground voltage (GND) to the individual electrode L1 and the common electrode C0 included in the liquid lens 28.

The capacitive measurement circuit 50 may be connected to the common electrode C0 side. The capacitance measurement circuit 50 connects the first switch SW1, which will be described later, to measure the capacitance of the liquid lens 28, and the amount of charge stored in the capacitor of the liquid lens 28 is the capacitance measurement circuit 50 Can be delivered to In addition to the comparator, the capacitance measurement circuit 50 may further include components, such as a capacitor, to measure the amount of charge transferred from the capacitor of the liquid lens 28.

The first switch can be disposed between the capacitive measurement circuit and the liquid lens.

Before measuring the capacitance of the liquid lens 28, the ground voltage GND is applied to the common electrode C0. Thereafter, when the first switch SW1 is connected (ON), the second switch SW0 of the voltage control circuit 40 is turned off to make the common electrode C0 a floating state. The second switch SW0 is a switch for applying the ground voltage GND to the common electrode C0. Thereafter, when the first switch SW1 is connected and the voltage VL1 applied to the individual electrode L1 to be measured is changed, electric charges stored in the capacitor of the liquid lens 28 (eg, Q (charge amount) = ΔVL1) x C (capacitance of the liquid lens) may be moved to the capacitive measurement circuit 50.

Fig. 9 explains the operation of the control circuit of Fig. 8;

As shown, a plurality of individual electrodes (L1, L2, L3, L4) and a common electrode (C0) of the liquid lens have a high voltage (e.g., 70V, 35V) and ground voltage (in accordance with timing controlled by a method of time division control). Yes, 0V) can be applied.

After the ground voltage is applied to the common electrode C0, that is, after the second switch SW0 of the voltage control circuit 40 is connected, the second switch SW0 is turned off and the common electrode C0 is floated In the state where the first switch SW1 in the capacitance measurement circuit 50 is connected (ON), the voltage applied to the individual electrodes L1, L2, L3, L4 falls from the high voltage to the ground voltage, and the capacitance of the capacitance falls at the falling edge. Measurements can be made.

There is a falling edge of the voltage VL3 applied to the third individual electrode L3 at the time when the first switch SW1 is first connected, such that the third between the third individual electrode L3 and the common electrode C0 Capacitance CL3 can be measured. Thereafter, when the first switch SW1 is connected, the fourth capacitance CL4 between the fourth individual electrode L4 and the common electrode C0, and between the second individual electrode L2 and the common electrode C0 The first capacitance CL1 between the second capacitance CL2 and the first individual electrode L1 and the common electrode C0 may be sequentially measured. During the period in which the first switch SW1 is turned on, voltage is not supplied to the common electrode C0 from the voltage control circuit.

Meanwhile, in order to measure the capacitance, the voltage control circuit may rotate voltages applied to a plurality of individual electrodes included in the liquid lens in clockwise or counterclockwise directions and transmit them at different times.

10 illustrates a second example of the control circuit. For convenience of description, one of the plurality of individual electrodes L1 will be described as an example.

As shown, the control circuit includes a voltage control circuit 40 and a capacitive measurement circuit 50 and can be connected to the liquid lens 28. The voltage control circuit 40 may selectively transfer one of the high voltage (eg, 70V, 35V) and the ground voltage (GND) to the individual electrode L1 and the common electrode C0 included in the liquid lens 28.

The capacitive measurement circuit 50 may be connected to the common electrode C0 side. The capacitance measurement circuit 50 connects the first switch SW1, which will be described later, to measure the capacitance of the liquid lens 28, and the amount of charge stored in the capacitor of the liquid lens 28 is the capacitance measurement circuit 50 Can be delivered to In addition to the comparator, the capacitance measurement circuit 50 may further include components, such as a capacitor, to measure the amount of charge transferred from the capacitor of the liquid lens 28.

The first switch can be disposed between the capacitive measurement circuit and the liquid lens.

The control circuit may further include a third switch SW3 disposed between the voltage control circuit 40 and the first switch and/or between the voltage control circuit and the liquid lens 28. One end of the third switch SW3 may be connected to the voltage control circuit, and the other end may be connected to the liquid lens and the first switch. The third switch SW3 may control the floating state in the process of measuring the capacitance by the capacitance measurement circuit 50 connected to the common electrode C0. In addition, the switch unit SW3, which is independently connected than controlling the floating state using a switch inside the voltage control circuit 40, may be effective in lowering the breakdown voltage of the switching element.

Before measuring the capacitance of the liquid lens 28, the third switch SW3 is connected to apply the ground voltage GND to the common electrode C0. Thereafter, the third switch SW3 floats the common voltage C0. When the first switch SW1 is connected (ON), when the voltage VL1 applied to the individual electrode L1 to be measured is changed, charges stored in the capacitor of the liquid lens 28 (eg, Q (charge amount)) = ΔVL1 x C (capacitance of the liquid lens) can be moved to the capacitance measurement circuit 50.

Fig. 11 explains the operation of the control circuit of Fig. 10;

As shown, a plurality of individual electrodes (L1, L2, L3, L4) and a common electrode (C0) of the liquid lens have a high voltage (e.g., 70V, 35V) and ground voltage (in accordance with timing controlled by a method of time division control). Yes, 0V) can be applied.

The measurement of the capacitance may be a time point when the ground voltage is applied to the common electrode C0, that is, the voltage control circuit 40 and the third switch SW3 may be connected. After the ground voltage GND is applied to the common electrode C0 while the third switch SW3 is connected, the third switch SW3 is turned off and the common electrode C0 is floated. The voltage applied to the individual electrodes L1, L2, L3, L4 in the state where the first switch SW1 in the capacitance measurement circuit 50 is connected (ON) while the common electrode C0 is floating is at a high voltage. When a falling edge falling to the ground voltage occurs, movement of the charge amount may be achieved.

There is a falling edge of the voltage VL3 applied to the third individual electrode L3 at the time when the first switch SW1 is first connected, such that the third between the third individual electrode L3 and the common electrode C0 Capacitance CL3 can be measured. Thereafter, when the second switch SW1 is connected, the fourth capacitance CL4 between the fourth individual electrode L4 and the common electrode C0, and between the second individual electrode L2 and the common electrode C0 The first capacitance CL1 between the second capacitance CL2 and the first individual electrode L1 and the common electrode C0 may be sequentially measured.

Depending on the embodiment, the liquid lens may have more than eight individual electrodes. However, the number of individual electrodes may be a multiple of four. Further, the number of feedback electrodes disposed in the liquid lens may be the same as or different from the number of individual electrodes included in the liquid lens.

Fig. 12 explains the connection of the liquid lens and the control circuit. In particular, FIG. 12 describes the connection of the control circuit described in FIG. 6 in more detail.

As shown, the liquid lens 28 is connected to a voltage control circuit 40 that supplies voltages to the individual and common electrodes of the liquid lens 28, and the capacitive measurement circuit 50 is a liquid lens 28 ) Can be connected to one of the two electrodes. The position to measure the capacitance in the liquid lens 28, that is, two electrodes having both sides of the capacitance may be selected as described in FIGS. 8 to 11 described above.

Meanwhile, the voltage control circuit 40 and the capacitance measurement circuit 50 are connected through a switching element SW_V. The switching element SW_V is turned on at a time when the capacitance in the liquid lens 28 is to be measured, and the input voltage VIN is boosted by the voltage control circuit 40 before it is boosted. Can be delivered to.

13 illustrates the timing of the switching elements shown in FIG. 12 for measuring the capacitance of a liquid lens. The specific operation of the capacitance measurement circuit 50 has already been described in FIG. 7. Here, the operation timing of the switching circuit described in FIG. 12 will be mainly described.

As shown, the switching element SW_V is turned on to measure the capacitance of the liquid lens, and to apply the voltage VIN for measuring the capacitance. Further, the fourth switch SW13 is turned on to connect the ground voltage SW13 to the reference capacitor Cap-m in the electrostatic capacity measurement circuit 50 to discharge electric charges.

Thereafter, when the fifth switch SW11 is connected, the charge accumulated due to the capacitance of the liquid lens moves to the reference capacitor Cap-m, turns off the fifth switch SW11, and then turns the reference capacitor Cap In -m), the value of the first capacitance can be sensed (1st cap sensing window).

Thereafter, the switching element SW_V is turned ON to apply the voltage VIN, and the sixth switch SW12 is turned ON. At this time, the charge accumulated in the reference capacitor (Cap-m) can move. Thereafter, in the state in which the switching element SW_V and the second switch SW12 are turned off, the value of the second capacitance may be sensed in the reference capacitor Cap-m (2nd cap sensing window).

Thereafter, a method of recognizing the capacitance of the liquid lens may be the same as described in FIG. 7.

The capacitance of the liquid lens calculated or measured by the capacitance measurement circuit may be transferred to the voltage control circuit. The voltage control circuit receiving the capacitance of the liquid lens can recognize the shape and state of the interface in the liquid lens through the capacitance. If the shape and state of the interface in the liquid lens differ from the target, the voltage control circuit can adjust the driving voltage.

As described above, in the control method of the liquid lens, the common electrode of the liquid lens is connected to the ground, a voltage is applied to the individual electrodes of the liquid lens, and electric charges are accumulated between the common electrode and the individual electrodes. And turning on a first switch disposed between the liquid lens and measuring a voltage across a reference capacitor of the capacitive measurement circuit. Thereafter, the capacitance between the common electrode and the individual electrodes may be calculated using the measured value of the voltage across the reference capacitor.

According to an embodiment, the control method of the liquid lens includes connecting one of the common electrode and the individual electrode of the liquid lens to ground, applying a voltage to the other of the common electrode and the individual electrode of the liquid lens, and the common electrode and the individual The step of accumulating charge between the electrodes, the step of turning on the first switch, the step of measuring the voltage across the reference capacitor of the capacitance measurement circuit, and using the measured value of the voltage across the reference capacitor to separate the common electrode from the And calculating the capacitance between the electrodes.

The liquid lens described above may be included in the camera module. The camera module includes a lens assembly including a liquid lens mounted on a housing and at least one solid lens that may be disposed on the front or rear surface of the liquid lens, an image sensor that converts an optical signal transmitted through the lens assembly into an electrical signal, and A control circuit for supplying a driving voltage to the liquid lens may be included.

Although only a few are described as described above in connection with the embodiments, various other forms of implementation are possible. The technical contents of the above-described embodiments may be combined in various forms unless it is a technology incompatible with each other, and may be implemented as a new embodiment.

It is possible to implement an optical device (optical device) including the above-described camera module. Here, the optical device may include a device capable of processing or analyzing an optical signal. Examples of the optical device may include a camera/video device, a telescope device, a microscope device, an interferometer device, a photometer device, a polarimeter device, a spectrometer device, a reflectometer device, an autocollimator device, a lens meter device, etc., and may include a liquid lens. Embodiments of the present invention can be applied to a possible optical device. Further, the optical device may be implemented as a portable device such as a smart phone, a notebook computer, and a tablet computer. The optical device may include a camera module, a display unit for outputting an image, and a body housing for mounting the camera module and the display unit. The optical device may further include a memory module in which a communication module capable of communicating with other devices may be mounted in the main body housing and store data.

The method according to the above-described embodiment may be manufactured as a program for execution on a computer and stored in a computer-readable recording medium. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, and magnetic tape. , Floppy disk, and optical data storage devices.

The computer-readable recording medium can be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. And, functional programs, codes, and code segments for implementing the above-described method can be easily inferred by programmers in the technical field to which the embodiment belongs.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all respects, but should be considered illustrative. The scope of the invention should be determined by rational interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

Claims (15)

A plate including a cavity in which the conductive liquid and the non-conductive liquid are disposed;
A plurality of individual electrodes disposed on the plate; and
A common electrode disposed under the plate;
A liquid lens comprising; And
Includes; a voltage control circuit for applying a driving voltage to the liquid lens,
Grounding the common electrode of the liquid lens, and applying a voltage to any one of the plurality of individual electrodes of the liquid lens;
Blocking a voltage from being applied to the common electrode of the liquid lens;
Electrically connecting a capacitive measurement circuit and the liquid lens;
Measuring a voltage across a capacitor of the capacitance measurement circuit; and
And controlling the driving voltage using the measured voltage across the capacitor. According to claim 1,
Calculating a capacitance between the common electrode and any one of the plurality of individual electrodes using the measured voltage across the capacitor of the capacitance measurement circuit; and
Controlling the driving voltage using the calculated capacitance;
Liquid lens control method comprising a. According to claim 2,
The capacitance measurement circuit is a liquid lens control method for sequentially calculating the capacitance between each of the plurality of individual electrodes and the common electrode. According to claim 2,
It includes; a first switch disposed between the voltage control circuit and the common electrode;
A method of controlling a liquid lens that blocks a voltage from being applied to the common electrode of the liquid lens by turning off the first switch. According to claim 2,
It includes; a second switch disposed between the liquid lens and the capacitive measurement circuit;
A liquid lens control method for electrically connecting the capacitive measurement circuit and the liquid lens by turning on the second switch. The method of claim 5,
And the step of turning on the second switch and measuring the voltage across the reference capacitor of the capacitive measurement circuit, wherein at least a portion of the accumulated charge moves to the reference capacitor. Way. The method of claim 5,
When the shape of the interface is changed by the driving voltage, after the ground voltage is applied to the common electrode, the common electrode is floating,
Liquid lens control for calculating the capacitance in a section in which the second switch is turned on and the voltage of at least one individual electrode among the plurality of individual electrodes is changed from a first voltage to a second voltage lower than the first voltage. Way. According to claim 2,
And feedbacking the capacitance calculated by the capacitance measurement circuit to the voltage control circuit. The method of claim 5,
A method of controlling a liquid lens, wherein the second switch is turned off while the voltage control circuit supplies the driving voltage to operate the liquid lens. The method of claim 5,
The voltage control circuit has a function of supplying a voltage to drive the liquid lens and
And a function of accumulating charge for measuring the capacitance in the liquid lens. The method of claim 5,
The capacitance measurement circuit is a liquid lens control method connected to the common electrode. The method of claim 5,
The voltage control circuit comprises a first voltage control circuit for supplying voltage to the common electrode and a second voltage control circuit for supplying voltage to the plurality of individual electrodes. The method of claim 5,
Further comprising a first switch disposed between the voltage control circuit and the second switch and between the voltage control circuit and the liquid lens,
The first switch is turned on (ON) while supplying a voltage to the common electrode, and the liquid lens control method is turned off (OFF) while the capacitance measurement circuit calculates the capacitance. A plate including a cavity in which the conductive liquid and the non-conductive liquid are disposed;
A plurality of individual electrodes disposed on the plate; and
A common electrode disposed under the plate;
Liquid lens comprising a;
A first lens unit disposed on the liquid lens;
A second lens unit disposed under the liquid lens; and
Includes; a lens module including; a printed circuit board on which an image sensor and a driving voltage control circuit electrically connected to the liquid lens are disposed.
Grounding the common electrode of the liquid lens, and applying a voltage to any one of the plurality of individual electrodes of the liquid lens;
Blocking a voltage from being applied to the common electrode of the liquid lens;
Electrically connecting a capacitive measurement circuit and the liquid lens;
Measuring a voltage across a capacitor of the capacitance measurement circuit; And
Controlling the driving voltage using a voltage across the capacitor;
Liquid lens control method comprising a. The method of claim 14,
And calculating a capacitance between the common electrode and any one of the plurality of individual electrodes using a voltage across the capacitor.

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