KR102358970B1 - Control circuit of liquid lens, camera module and controlling method for liquid lens - Google Patents

Abstract

The present invention provides a voltage control circuit for transferring a driving voltage to a plurality of individual electrodes and a common electrode for controlling the interface of a liquid lens, and a charge amount according to the capacitance of the interface in response to a change in the driving voltage transferred to the plurality of individual electrodes A control circuit for a liquid lens comprising a capacitance measuring circuit for receiving and measuring a capacitance is provided.

Description

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 electrical 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.) is desired. Such a photographing function may be implemented through a method of directly moving a lens by combining a plurality of lenses, but if the number of lenses is increased, the size of the optical device may increase. Autofocus and image stabilization 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 device is used. However, the lens driving device consumes high power, and in order to protect it, a cover glass must be added separately from the camera module, so the overall thickness is increased. Therefore, research on a liquid lens that performs autofocus and image stabilization functions by electrically controlling the curvature of the interface between two liquids is being conducted.

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 by using electric energy. Correspondingly, the movement of the interface of the liquid lens can be recognized more accurately and the interface of the liquid lens can be more accurately controlled.

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

In addition, the present invention provides a poling in which a common electrode is a ground voltage and an individual electrode falls from a high voltage (eg, 10 to 50 V or more) to a ground voltage so that the capacitance between the electrodes disposed in a liquid lens with adjustable focal length can be measured. An apparatus and method for measuring capacitance by floating a common electrode at a falling edge may be provided.

In addition, the present invention does not recognize the movement and shape of the interface of the liquid lens that can adjust the focal length by converting the optical signal passing through the interface into an image, but directly recognizes the movement and shape of the interface through the change in the capacitance of the interface By doing so, it is possible to more precisely control the performance and operation of the liquid lens.

In addition, the present invention can recognize the movement and shape of the interface in the liquid lens, so that a more efficient camera device or optical device for correcting lens distortion or controlling the 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 of ordinary skill in the art to which the present invention belongs from the description below. will be able

A liquid lens control circuit 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 for supplying a voltage to the liquid lens to control an interface of the liquid lens; and a capacitance measuring circuit for calculating a capacitance between the common electrode of the liquid lens and the plurality of individual electrodes; and a first switch disposed between the capacitance measuring 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 capacitance measuring circuit may include 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 measuring circuit.

Also, the capacitance measuring circuit may be connected to the common electrode.

Also, the capacitance measuring 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 for supplying a voltage to the common electrode and a second voltage control circuit for supplying a voltage to the plurality of individual electrodes.

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

In addition, the common electrode may be floated to measure the capacitance.

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

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

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, wherein the third switch supplies a voltage to the common electrode. It may be turned on while the capacitance measurement circuit is being 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 for supplying a voltage to the liquid lens to control an interface of the liquid lens; and a capacitance measuring 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 capacitance measuring circuit and the liquid lens; a lens assembly comprising 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 forms a cavity in which a conductive liquid and a 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 may be disposed under the first plate.

A liquid lens control method according to another embodiment of the present invention includes the steps of: connecting a common electrode of a liquid lens to a ground, applying a voltage to the individual electrodes of the liquid lens, and accumulating charges between the common electrode and the individual electrodes; turning on a first switch disposed between the capacitance measuring circuit and the liquid lens; measuring the voltage across the reference capacitor of the capacitance measuring circuit; and calculating a capacitance between the common electrode and the individual electrode by using the measured 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, in the liquid lens control method, at least a portion of the accumulated charge moves to the reference capacitor between the step of turning on the first switch and the step of measuring the voltage across the reference capacitor of the capacitance measuring circuit. It may include further steps.

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 descriptions of the present invention that will be described below by those of ordinary skill in the art can be derived and understood based on

The effect on the device according to the present invention will be described as follows.

The present invention can provide a method and an apparatus capable of more accurately measuring the movement and change of an interface.

In addition, the present invention can accurately measure the movement and shape of the interface within the liquid lens, so that more efficient optical stabilization can be performed on an image or image obtained by converting an 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, so that 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 can be improved.

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 of ordinary skill in the art to which the present invention belongs 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 the change of the interface within the liquid lens.
Fig. 6 illustrates a control circuit that cooperates with a liquid lens.
7 illustrates an example of a capacitance measuring circuit.
Fig. 8 describes 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;
12 illustrates the connection of the liquid lens and the control circuit.
Fig. 13 explains the timing of the switching elements shown in Fig. 12 for measuring the capacitance of the liquid lens.

Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings. Since the embodiment may have various changes and may have various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the embodiment to a specific disclosed form, and it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the embodiment.

Terms such as “first” and “second” may be used to describe various elements, but the elements should not be limited by the terms. These terms are used for the purpose of distinguishing one component from another. In addition, terms specifically defined in consideration of the configuration and operation of the embodiment are only for describing the embodiment, and do not limit the scope of the embodiment.

In the description of the embodiment, in the case where it is described as being formed in "up (up)" or "below (on or under)" of each element, on (on or under) ) includes both elements in which two elements are in direct contact with each other or one or more other elements are disposed between the two elements indirectly. In addition, when expressed as “up (up)” or “down (on or under)”, the meaning of not only the upward direction but also the downward direction based on one element may be included.

Also, as used hereinafter, relational terms such as "upper/upper/above" and "lower/lower/below" etc. do not necessarily require or imply any physical or logical relationship or order between such entities or elements, It may be used to distinguish one entity or element from another entity or element.

1 illustrates an example of a camera device. As shown, the camera module may 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 applied to the first lens. may include a control circuit 24 for supplying, and an image sensor 26 arranged on the lens assembly 22 and configured to convert 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. However, 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 . may include The connection unit 500 electrically connects the image sensor and the liquid lens, and may include a substrate, a wire, or an electric wire, which will be described later. The illustrated structure of the lens assembly 22 is only one example, and the structure of the lens assembly 22 may vary 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 located above (front), and either 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 level of the operating voltage applied to the lens assembly 22 is reduced, the control circuit 24 may be implemented as a single chip. Accordingly, 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 shown, 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 unit 500 electrically connects the image sensor and the liquid lens, and may include a substrate, a wire, or an electric wire, which will be described later. The illustrated structure of the lens assembly 22 is only one example, and the structure of the lens assembly 22 may vary 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 located above (front), and either 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 on which light is incident from the outside of the lens assembly. The first lens unit 100 may be provided as 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 may be 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 to the outside of the lens holder 400 and be exposed to the outside. When a 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 be deteriorated. In order to prevent or suppress surface damage of the solid lens 110, a method of disposing a cover glass or forming a coating layer or forming the solid lens 100 with a wear-resistant material to prevent 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 to the first lens unit 100 from the outside passes through the liquid lens unit 300 . Thus, it can be incident to the second lens unit 200 . The second lens unit 200 may be spaced apart from the first lens unit 100 and 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, the optical system may be formed by aligning the second lens unit 200 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 partial area 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 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 the light passing through the first lens unit 100 transmits, and at least a portion thereof may include a liquid. For example, the lens region 310 may include two types, namely, a conductive liquid and a non-conductive liquid, and the conductive liquid and the non-conductive liquid may form an interface without being mixed 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 , so that the curvature of the interface of the liquid lens 28 or the focal length of the liquid lens may be changed. When the boundary surface deformation and curvature change are controlled, the liquid lens unit 300 and the camera module including the same may perform an auto-focusing function, a hand-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 (refer to FIG. 2), and (b) describes the equivalent circuit of the lens 28. As shown in FIG.

First, referring to (a), the lens 28 whose focal length is adjusted in response to the driving voltage has the same angular distance and the voltage through the individual terminals L1, L2, L3, and L4 arranged in four different directions. can be authorized. The individual terminals may be disposed 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 the 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 electrically conductive liquid and the non-conductive liquid may be deformed.

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

4 illustrates the structure of a liquid lens.

As shown, the liquid lens 28 may include a liquid, a first plate, and an electrode. The liquids 122 and 124 included in the liquid lens 28 may include a conductive liquid and a non-conductive liquid. 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 above (below) 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 a liquid lens 28 may include an interface 130 formed by two different liquids 122 , 124 . It may also 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, but the second plate or third plate is not disposed on a part of the upper surface or lower surface of the liquid lens corner. may be thinner than the central portion. An electrode may be exposed on the upper or lower surface of the 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 unit 500 . The connection part may include at least one of the first substrate 142 and the second substrate 144 . When the connecting portion includes the first substrate 142 and the second substrate 144 , the second substrate 144 may transmit a voltage to each of a plurality of individual terminals, and the first substrate 142 may apply a voltage to the common terminal. can transmit The plurality of individual terminals may be four, and the second substrate 144 may transmit a 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 an opening having a preset inclined surface. It may include a first plate 114 including a region.

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

In addition, 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 . may include The first plate 114 may include an inclined surface and further include an insulating layer 118 disposed on the inclined surface. The conductive liquid may contact the insulating layer. Here, the insulating layer 118 covers one of the two electrodes 132 and 134 (eg, the second electrode 134 ) and partially covers the other electrode (eg, the first electrode 132 ). or exposed to cause 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 in a clockwise direction with respect to the optical axis. The electrode sector may be referred to as a sub-electrode or a terminal of a liquid lens.

One or two or more substrates 142 and 144 for transferring 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 is changed in response to the driving voltage.

5 illustrates the change of the interface within the liquid lens. Specifically, (a) to (c) describe the movement of the interfaces 30a, 30b, and 30c that may occur when voltage is applied to the individual electrodes L1, L2, L3, and 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 top, 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 be balanced. In this case, the capacitance value of the interface 30a measured through the four different individual electrodes L1, L2, L3, and L4 may be measured to be 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. A case where the applied voltage is higher than the applied voltage will be described. In this case, since the force to pull or push the interface 30b is different horizontally or vertically, the horizontal distance (LH) of the interface when viewed from the top may be shorter than the vertical distance (LV)) of the interface when viewed from the top. . When the voltages applied to the second individual electrode L2 and the fourth individual electrode L4 are lower than those of the first individual electrode L1 and the third individual electrode L3, the second individual electrode L2 and the fourth individual electrode L4 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, capacitance values of the interface 30a measured through the four different individual electrodes L1 , L2 , L3 , and L4 may be different from each other. Meanwhile, since the interface 30b is symmetrically changed with respect to the interface 30b, the capacitance value of the interface 30a measured through the four different individual electrodes L1, L2, L3, and L4 may be symmetrical. In this case, the capacitance values of L1 and L3 may be the same, and the capacitance values of L2 and L4 may be the same.

Also, 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 As the voltage applied to the 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 separate electrodes L1, L2, L3, and L4 of the interface 30c may be different from each other. Meanwhile, since the interface 30c is symmetrically changed to the interface 30b, the capacitance value of the interface 30a measured through the four different individual electrodes L1, L2, L3, and L4 may be symmetrical. In this case, the capacitance values of L1 and L3 may be the same, and the capacitance values of L2 and L4 may be the same.

In addition, there is a difference in capacitance measured at the interfaces 30a, 30b, and 30c shown in (a), (b) and (c), and the first individual electrode L1 to the fourth individual electrode L1 through the difference in capacitance Depending on the voltage applied to the electrode L4, how the interfaces 30a, 30b, and 30c move differently from before may be more directly and accurately measured.

Meanwhile, in the above example, the liquid lens 28 has been described with a structure including four individual electrodes, but the liquid lens 28 has more individual electrodes such as 8, 12, 16, etc. When the feedback electrode is included, the movement of the liquid lens 28 can be more precisely controlled, and the corresponding movement can be measured more accurately.

Fig. 6 illustrates a control circuit that cooperates with a liquid lens.

As shown, the liquid lens 28 includes four individual electrodes L1, L2, L3, and L4 and one common electrode C0 (see FIG. 3). The voltage control circuit 40 generates voltages V _L1 , V _L2 , V _L3 , V _L4 , V _C0 applied to the four individual electrodes L1 , L2 , L3 and L4 and one common electrode C0 . can be supplied. 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 correspond to the first electrode ( 132) can be addressed.

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

The voltage control circuit 40 converts the voltages V _L1 , V _L2 , V _L3 , V _L4 , V _C0 at a level of at least 0V to 80V to four individual electrodes L1 , L2 , L3 , L4 and a common electrode C0 ) can be provided at the same time or at different times. The voltage control circuit 40 does not apply a voltage to the four individual electrodes L1 , L2 , L3 , and 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 transmitted in response to the generated timing.

As shown, the liquid lens 28 interface 30 is connected to the voltages V _L1 , V _L2 , V _L3 , V _L4 delivered to the plurality of individual electrodes L1 , L2 , L3 , L4 and the common electrode C0 . , V _C0 ) may be controlled in response to the driving voltage formed. Changes in the movement, position, or shape of the interface 30 within the liquid lens 28 include the first to fourth voltages V _L1 , V _L2 , V _L3 , and V _L4 and the voltage applied to the common electrode C0 ( It can be caused by the voltage difference of V _C0 ).

Movement and position of the interface 30 within the liquid lens 28 by the voltage difference between the first to fourth voltages V _L1 , V _L2 , V _L3 , V _L4 and the voltage V _C0 of the common electrode C0 , or when a change in shape occurs, a change in capacitance may occur. Movement of the interface 30 within the liquid lens 28 . A change in capacitance caused by a change in position or shape may be in a small range of several pF to several tens of pF.

The position or shape of the interface 30 due to the voltage applied to the first to fourth individual electrodes L1, L2, L3, and L4 is common after the ground voltage GND and 0V is applied to the common electrode C0. The measurement may be performed by floating the electrode C0. More specifically, first to fourth voltages V _L1 , V _L2 , which float the common electrode C0 and are applied to one of the first to fourth individual electrodes L1 , L2 , L3 and L4 , When V _L3 , V _L4 ) is a falling edge or a rising edge that falls from a high voltage (eg, 10-80V) to a ground voltage (0V), the capacitance can be measured using the change in voltage applied to the corresponding electrode. can (Ground Floating Edge Measurement)

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

For example, the capacitance measuring circuit 54 for measuring a change in a small capacitance of several pF to several tens of pF does not measure the capacitance of any absolute value, but measures one or both of the two capacitors of which the value is already known. The change in capacitance can be measured through differential comparison, which measures capacitance through the difference in the amount of physical change that occurs when exposed to external changes.

As another example, the capacitance measuring circuit 54 for measuring a small capacitance of several pF to several tens of pF calculates a 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 this method.

The capacitance measuring circuit 50 transmits the calculated or measured information to the voltage control circuit 40 , and the voltage control circuit 40 corresponds to the information and the voltages V _L1 , V _L2 , V _L3 , V _L4 , V _C0 ) can be adjusted. The information calculated or measured by the capacitance measuring circuit may be a voltage or a capacitance value. The information calculated by the capacitance measurement circuit may be transmitted to the voltage control circuit, and the voltage control circuit may configure a liquid lens control circuit that adjusts the driving voltage using the calculated information.

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

As shown, 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 measuring circuit 54 connected to the other C0 is connected to the two electrodes L1. , C0), the state of the interface 30 can be recognized by measuring the capacitance.

When the voltage V _L1 is applied and the first switch SW1 in the voltage control circuit 40 is connected, the amount of charge Q on the interface 30 is the amount of change in voltage ΔV _L1 , the capacitance of the interface 30 . It can be equal to multiplying by (C). 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 OFF and the second switch SW1 is ON at a falling edge where the voltage V _L1 drops to the ground voltage, the reference capacitor Cap-m ) can move to the on-chip capacitor (Cap-on). In this case, the amount of charge Q moving to the on-chip capacitor Cap-on may be equal to the amount of change ΔV _L1 in the feedback voltage 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 to 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) becomes 0. The ratio of the two capacitances is obtained from the ratio. Since the capacitance of the on-chip capacitor Cap-on is a known value, the capacitance of the capacitance C of the interface 30 may be measured.

The configuration of the above-described capacitance measuring circuit 54 may vary depending on the embodiment, and accordingly, an operation and a control method thereof may also be different. Here, the capacitance measuring circuit 54 may be designed to measure a change of several pF to 200 pF.

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

In addition, as a circuit for measuring capacitance, a switched capacitor circuit, which can be composed of only a capacitor and a switch, has a higher degree of directness than an LC series resonance circuit that must include all of a resistor, an inductor, and a capacitor, so it can be easily applied to mobile devices. . One end of the first switch may be electrically connected to the liquid lens and the voltage control circuit.

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

As shown, the control circuit includes a voltage control circuit 40 and a capacitance measurement circuit 50 , and may be coupled to the liquid lens 28 . The voltage control circuit 40 may selectively transmit 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 capacitance measuring circuit 50 may be connected to the common electrode C0 side. When a first switch SW1, which will be described later, is connected to the capacitance measuring circuit 50 to measure the capacitance of the liquid lens 28, the amount of charge stored in the capacitor of the liquid lens 28 is the capacitance measuring circuit 50 can be transmitted to The capacitance measuring circuit 50 may further include components such as a capacitor in addition to the comparator, so that it is possible to measure the amount of charge transferred from the capacitor of the liquid lens 28 .

The first switch may be disposed between the capacitance measurement circuit and the liquid lens.

Before measuring the capacitance of the liquid lens 28, a 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. After that, when the first switch SW1 is connected and the voltage V _L1 applied to the individual electrode L1 to be measured is changed, the charges stored in the capacitor of the liquid lens 28 (eg, Q (charge amount) = ΔV _L1 x C (capacitance of the liquid lens)) can be moved to the capacitance measurement circuit 50 .

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

As shown, the plurality of individual electrodes (L1, L2, L3, L4) and the common electrode (C0) of the liquid lens have a high voltage (eg, 70V, 35V) and a ground voltage ( Yes, 0V) can be applied.

A state in which the second switch SW0 is turned off and the common electrode C0 is floated after the time when the ground voltage is applied to the common electrode C0, that is, the time when the second switch SW0 of the voltage control circuit 40 is connected In the state in which the first switch SW1 in the capacitance measuring circuit 50 is connected (ON), the voltage applied to the individual electrodes L1, L2, L3, L4 Measurements can be made.

When the first switch SW1 is connected for the first time, there is a falling edge of the voltage V _L3 applied to the third individual electrode L3, and there is a second connection between the third individual electrode L3 and the common electrode C0. 3 Capacitance (C _L3 ) can be measured. Thereafter, when the first switch SW1 is connected, the fourth capacitance C _L4 between the fourth individual electrode L4 and the common electrode C0, the second individual electrode L2 and the common electrode C0 The second capacitance C _L2 , and the first capacitance C _L1 between the first individual electrode L1 and the common electrode C0 may be sequentially measured. No voltage is supplied from the voltage control circuit to the common electrode C0 during the period in which the first switch SW1 is turned on.

Meanwhile, for capacitance measurement, the voltage control circuit may rotate the voltage applied to the plurality of individual electrodes included in the liquid lens in a clockwise or counterclockwise direction to transmit the voltage at different time points.

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

As shown, the control circuit includes a voltage control circuit 40 and a capacitance measurement circuit 50 , and may be coupled to the liquid lens 28 . The voltage control circuit 40 may selectively transmit 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 capacitance measuring circuit 50 may be connected to the common electrode C0 side. When a first switch SW1, which will be described later, is connected to the capacitance measuring circuit 50 to measure the capacitance of the liquid lens 28, the amount of charge stored in the capacitor of the liquid lens 28 is the capacitance measuring circuit 50 can be transmitted to The capacitance measuring circuit 50 may further include components such as a capacitor in addition to the comparator, so that it is possible to measure the amount of charge transferred from the capacitor of the liquid lens 28 .

The first switch may be disposed between the capacitance 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 while the capacitance measuring circuit 50 connected to the common electrode C0 measures the capacitance. In addition, rather than controlling the floating state using a switch inside the voltage control circuit 40 , the independently connected switch unit SW3 may be effective in lowering the withstand 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), if the voltage V _L1 applied to the individual electrode L1 to be measured is changed, the charges stored in the capacitor of the liquid lens 28 (eg, Q (charge amount) ) = ΔV _L1 x C (capacitance of the liquid lens)) can be moved to the capacitance measuring circuit 50 .

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

As shown, the plurality of individual electrodes (L1, L2, L3, L4) and the common electrode (C0) of the liquid lens have a high voltage (eg, 70V, 35V) and a ground voltage ( Yes, 0V) can be applied.

Capacitance is measured 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. In a state in which the common electrode C0 is floating and the first switch SW1 in the capacitance measuring circuit 50 is connected (ON), the voltage applied to the individual electrodes L1, L2, L3, and L4 is at a high voltage. When a falling edge that drops to the ground voltage occurs, the amount of electric charge can be transferred.

When the first switch SW1 is connected for the first time, there is a falling edge of the voltage V _L3 applied to the third individual electrode L3, and there is a second connection between the third individual electrode L3 and the common electrode C0. 3 Capacitance (C _L3 ) can be measured. Thereafter, when the first switch SW1 is connected, the fourth capacitance C _L4 between the fourth individual electrode L4 and the common electrode C0, the second individual electrode L2 and the common electrode C0 The second capacitance C _L2 , and the first capacitance C _L1 between the first individual electrode L1 and the common electrode C0 may be sequentially measured.

Depending on the embodiment, a liquid lens may have more than eight individual electrodes. However, the number of individual electrodes may be a multiple of 4. Also, 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.

12 illustrates 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 capacitance measurement circuit 50 is connected to the liquid lens 28 ) can be connected to one of the two electrodes. Positions to measure the capacitance in the liquid lens 28, that is, the two electrodes on both sides having the capacitance may be selected as described with reference to FIGS. 8 to 11 described above.

Meanwhile, the voltage control circuit 40 and the capacitance measuring circuit 50 are connected through the switching element SW_V. At a point in time when the capacitance in the liquid lens 28 is to be measured, the switching element SW_V is turned on to measure the input voltage VIN before being boosted in the voltage control circuit 40 by the capacitance measuring circuit 50 can be transmitted as

Fig. 13 explains the timing of the switching elements shown in Fig. 12 for measuring the capacitance of the liquid lens. The specific operation of the capacitance measuring circuit 50 has already been described with reference to FIG. Here, the operation time of the switching circuit described with reference to FIG. 12 will be mainly described.

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

Thereafter, when the fifth switch SW11 is connected, the charges accumulated due to the capacitance of the liquid lens move to the reference capacitor Cap-m, and after turning off the fifth switch SW11, the reference capacitor Cap -m) can sense the value of the first capacitance (1 ^st 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. In this case, the charges accumulated in the reference capacitor Cap-m may move. Thereafter, in a 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 from the reference capacitor Cap-m (2 ^nd cap sensing window).

Thereafter, the method of recognizing the capacitance of the liquid lens may be the same as that described with reference to FIG. 7 .

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

As described above, the liquid lens control method includes the steps of connecting a common electrode of the liquid lens to the ground, applying a voltage to the individual electrodes of the liquid lens, and accumulating electric charges between the common electrode and the individual electrodes, a capacitance measuring circuit and turning on a first switch disposed between the liquid lens and measuring a voltage across a reference capacitor of a capacitance measuring circuit. Thereafter, the capacitance between the common electrode and the individual electrode may be calculated using the measured 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 the ground, applying a voltage to the other one of the common electrode and the individual electrode of the liquid lens, and the common electrode and the individual electrode A step of accumulating a charge between the electrodes, turning on the first switch, measuring the voltage across the reference capacitor of the capacitance measuring circuit, using the measured value of the voltage across the reference capacitor to separate the common electrode and the It may include calculating a 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 can be disposed on the front or rear side 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 have been described as described above in relation to the embodiments, various other forms of implementation are possible. The technical contents of the above-described embodiments may be combined in various forms unless they are incompatible with each other, and may be implemented in a new embodiment through this.

An optical device including the above-described camera module may be implemented. Here, the optical device may include a device capable of processing or analyzing an optical signal. Examples of optical devices include camera/video devices, telescope devices, microscope devices, interferometer devices, photometric devices, polarimeter devices, spectrometer devices, reflectometer devices, autocollimator devices, lensmeter devices, etc., and may include liquid lenses. The embodiment of the present invention can be applied to optical devices capable of Also, the optical device may be implemented as a portable device such as a smart phone, a notebook computer, or a tablet computer. Such an optical device may include a camera module, a display unit for outputting an image, and a body housing on which the camera module and the display unit are mounted. The optical device may have a communication module capable of communicating with other devices mounted on the main housing and may further include a memory unit capable of storing data.

The method according to the above-described embodiment may be produced as a program to be executed by a computer and stored in a computer-readable recording medium. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape. , floppy disks, optical data storage devices, and the like.

The computer-readable recording medium is distributed in a network-connected computer system, so that the computer-readable code can be stored and executed in a distributed manner. In addition, 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 is 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 characteristics of the present invention. Accordingly, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (20)

a holder including a first sidewall having a first hole formed therein;
a variable focus lens disposed in the first hole and including a common electrode and a plurality of individual electrodes;
a voltage control circuit supplying a driving voltage to the variable focus lens to control a boundary of the variable focus lens, and supplying the driving voltage according to a capacitance between at least one individual electrode of the plurality of individual electrodes and the common electrode;
a capacitance measuring circuit for measuring the capacitance between the at least one individual electrode of the plurality of individual electrodes and the common electrode; and
a first switch disposed between the capacitance measuring circuit and the variable focus lens;
One side of the first switch is electrically connected to the variable focus lens and the voltage control circuit. delete delete delete delete The camera module of claim 1 , further comprising a third switch positioned between the voltage control circuit and the first switch and between the voltage control circuit and the variable focus lens. The method of claim 6, wherein the third switch is
A camera module that is turned on when a common electrode voltage is applied to the common electrode, and is turned off when the capacitance measuring circuit measures the capacitance. According to claim 1,
When the common electrode floats after a ground voltage is supplied to the common electrode after the shape of the boundary is changed by the driving voltage, the capacitance is measured during a period in which the first switch is turned on, and the at least one individual The voltage supplied to the electrode is changed from a first voltage to a second voltage having a level lower than the first voltage. The camera module of claim 1 , wherein the first switch is turned off when the voltage control circuit supplies the driving voltage to the variable focus lens to operate the variable focus lens. The method of claim 1, wherein the voltage control circuit is
a first voltage control circuit for supplying a common electrode voltage to the common electrode; and
a second voltage control circuit for respectively supplying individual electrode voltages to the plurality of individual electrodes;
The driving voltage is generated through an interaction between at least one of the individual electrode voltages and the common electrode voltage. The camera module of claim 10 , wherein the common electrode voltage and the at least one individual electrode voltage are respectively applied to the common electrode and the individual electrode at different times. The method of claim 1, wherein the voltage control circuit is
A camera module for generating the driving voltage used to operate the variable focus lens, as well as accumulating an electric charge used to measure the capacitance between the common electrode and the at least one individual electrode. 2. The method of claim 1, wherein the capacitance measurement circuit comprises a reference capacitor;
wherein the capacitance between the common electrode and the at least one individual electrode is measured using the reference capacitor. delete The camera module of claim 1 , wherein the holder includes a first plate having a cavity in which the variable focus lens is disposed. delete delete delete delete a holder including a first sidewall having a first hole formed therein;
a variable focus lens disposed on the holder and including a common electrode and a plurality of individual electrodes;
a voltage control circuit supplying a driving voltage to the variable focus lens to control a boundary of the variable focus lens, and supplying the driving voltage according to a capacitor between at least one individual electrode among the plurality of individual electrodes and the common electrode;
a capacitance measuring circuit for measuring the capacitor between the at least one individual electrode of the plurality of individual electrodes and the common electrode; and
a first switch located between the capacitance measuring circuit and the variable focus lens;
a third switch located between the voltage control circuit and the first switch and between the voltage control circuit and the variable focus lens;
the capacitance measuring circuit measures a capacitance between the common electrode and each of the plurality of individual electrodes;
One surface of the first switch is electrically connected to the variable focus lens and the voltage control circuit,
the third switch is turned on when a common electrode voltage is applied to the common electrode and is turned off when the capacitance measuring circuit measures the capacitance;
When the common electrode floats after a ground voltage is supplied to the common electrode after the shape of the boundary is changed by the driving voltage, the capacitance is measured during a period in which the first switch is turned on, and the at least one individual The voltage supplied to the electrode is changed from the first voltage to a second voltage having a level lower than the first voltage,
the first switch is turned off when the voltage control circuit supplies the driving voltage to the variable focus lens to operate the variable focus lens;
The voltage control circuit may include: a first voltage control circuit for supplying a common electrode voltage to the common electrode; and a second voltage control circuit for respectively supplying individual electrode voltages to the plurality of individual electrodes;
the driving voltage is generated through an interaction between at least one of the individual electrode voltages and the common electrode voltage;
the common electrode voltage and the at least one individual electrode voltage are respectively applied to the common electrode and the individual electrode at different times;
the voltage control circuit not only generates the drive voltage used to operate the variable focus lens, but also accumulates an electric charge used to measure the capacitance between the common electrode and the at least one individual electrode;
the capacitance measuring circuit comprises a reference capacitor;
the capacitance between the common electrode and the at least one individual electrode is measured using the reference capacitor,
The holder includes a second sidewall opposite to the first sidewall in a first direction perpendicular to the optical axis and a first plate having a cavity in which the variable focus lens is disposed.

Images