KR102362732B1 - Control circuit of liquid lens and liquid lens module - Google Patents

Abstract

The present invention provides a liquid lens comprising a common electrode, a first feedback electrode, a plurality of individual electrodes, and a second feedback electrode; a voltage control circuit for supplying a voltage to the liquid lens to control an interface of the liquid lens; and a capacitance measurement circuit for calculating a capacitance between the first feedback electrode and the second feedback electrode of the liquid lens.

Description

CONTROL CIRCUIT OF LIQUID LENS AND LIQUID LENS MODULE

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, which increases the overall thickness. 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.

Publication No. 10-2009-0018965 (February 24, 2009)

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 to respond to the applied 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 capacitance measurement significantly lower than the driving voltage (eg, 30 to 50 V or more) so as to measure the capacitance of the interface included in the liquid lens between the electrode sectors disposed on the liquid lens with adjustable focal length. It is possible to provide a liquid lens structure capable of including a separate electrode to which a feedback voltage (eg, 1.5 to 5V) can be applied.

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 it is more efficient to correct lens distortion in a lens assembly including a liquid lens and a solid lens or to control the lens assembly, such as a camera device or an optical device 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 common electrode, a first feedback electrode, a plurality of individual electrodes, and a second feedback 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 first feedback electrode and the second feedback electrode of the liquid lens.

In addition, the second feedback electrode may be disposed between the plurality of individual electrodes, and the first feedback electrode may be disposed at a position corresponding to the second feedback electrode.

In addition, the liquid lens control circuit includes a feedback voltage control circuit that transmits a feedback voltage to one of the first feedback electrode and the second feedback electrode in order to measure the capacitance between the first feedback electrode and the second feedback electrode. may include more.

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 in response to the calculated information.

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

In addition, the voltage supplied to the liquid lens may include a level at least 2 to 10 times greater than the feedback voltage.

In addition, the feedback voltage has a range of 1.5 ~ 5V, the voltage supplied to the liquid lens may have a range of 10 ~ 80V.

A liquid lens module according to another embodiment of the present invention includes: a first plate including a cavity in which a conductive liquid and a non-conductive liquid are disposed; a first electrode disposed on the first plate; a plurality of second electrodes disposed under the first plate; a second plate disposed on the first plate; a third plate disposed under the first plate; a first feedback electrode disposed adjacent to the first electrode; and a second feedback electrode disposed between the plurality of second electrodes.

In addition, the liquid lens module may include: a first substrate for transmitting a voltage to the first electrode or a feedback voltage to the first feedback electrode; and a second substrate for transmitting a voltage to the second electrode or a feedback voltage to the second feedback electrode.

In addition, the first electrode may be a common electrode, the second electrode may be an individual electrode, and the number of the second feedback electrodes may be the same as the number of the second electrodes.

In addition, the liquid lens module may further include an insulating film covering the plurality of second electrodes and the second feedback electrode on the cavity.

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 apparatus capable of more accurately measuring the movement and change of an interface in response to a driving voltage applied to control an interface in a liquid lens with adjustable focal length.

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.
Figure 5 illustrates a feedback circuit in conjunction with a liquid lens.
6 illustrates the change of the interface within the liquid lens.
7 illustrates the electrode structure of the liquid lens.
8 illustrates an example of a capacitance measuring circuit.
Fig. 9 explains the connection part of the liquid lens.
Fig. 10 illustrates the connection of the liquid lens and the control circuit.
Fig. 11 explains the timing of the switching elements shown in Fig. 10;

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. 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. It may include a control circuit 24 for supplying, and an image sensor 26 arranged in the lens assembly 22 and converting the light transmitted through the lens assembly 22 into an electrical signal.

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 electrode may include a first electrode disposed on the first plate and a plurality of second electrodes disposed under the first plate. 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.

Figure 5 illustrates a feedback circuit in conjunction with a liquid lens. The liquid lens may include a common electrode, a first feedback electrode, a plurality of individual electrodes, and a second feedback electrode. The capacitance measuring circuit may calculate a capacitance between the first feedback electrode and the second feedback electrode. The second feedback electrode may be disposed between the plurality of individual electrodes, and the first feedback electrode may be disposed at a position corresponding to the second feedback electrode. The first feedback electrode may be disposed adjacent to the first electrode, and the second feedback electrode may be disposed between the plurality of second electrodes. The connector may include a first substrate and a second substrate, the first substrate may transmit a voltage to the first feedback electrode, and the second substrate may transmit a voltage to the second electrode or a feedback voltage to the second feedback electrode. can The first electrode may be a common electrode and the second electrode may be an individual electrode. The number of the second feedback electrodes may be the same as the number of the second electrodes. An insulating layer covering the plurality of second electrodes and the second feedback electrode may be included on the cavity of the liquid lens. The capacitance measuring circuit may calculate a capacitance between two first feedback electrodes of the plurality of first feedback electrodes of the liquid lens. The first feedback electrode may be disposed between the plurality of individual electrodes. The first feedback electrode may be disposed adjacent to the common electrode.

As shown, the liquid lens 28 includes four individual electrodes L1, L2, L3, and L4 and one common electrode C0 (not shown). The voltage control circuit 40 controls the driving 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. It can be created and 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 feedback circuit 50 is for measuring the movement of the interface 30 within the liquid lens 28 . The interface 30 within the liquid lens 28 can be understood and measured as a capacitance (capacitance) as described with reference to FIG. 3 . In order to measure the change in capacitance of the interface 30 in the liquid lens 28 , at least one feedback electrode F1 , F2 , F3 , F4 included in the liquid lens 28 may be used.

The feedback circuit 50 may include a feedback voltage control circuit 52 and a capacitance measurement circuit 54 . The feedback voltage control circuit may transmit a feedback voltage to one of the first feedback electrode and the second feedback electrode to measure a capacitance between the first and second feedback electrodes. The feedback voltage control circuit 52 outputs a feedback voltage V _F for measuring capacitance to at least one of the feedback electrodes F1 , F2 , F3 , and F4 . Since the voltages V _L1 , V _L2 , V _L3 , V _L4 , and V _C0 output to the voltage control circuit 40 are high voltages of at least 10V to 80V, the interface 30 has a very small size (about tens to 200pF) ) may not be suitable for measuring the capacitance of Accordingly, the feedback voltage control circuit 52 may supply the feedback voltage V _F , which may have a low level (about, 1.5V to 5V), to the at least one feedback electrode F1 , F2 , F3 , F4 . have. The feedback voltage may have a range of 1.5-5V, and the voltage supplied to the liquid lens may have a range of 10-80V.

The feedback circuit 50 may transmit a feedback voltage to any one of the two different feedback electrodes in order to measure the capacitance between the two different feedback electrodes and the feedback electrodes. Two different feedback electrodes may be included in the liquid lens. The liquid lens includes a first plate including a cavity in which a conductive liquid and a non-conductive liquid are disposed, a common electrode and a first feedback electrode disposed above the first plate, and a plurality of individual electrodes and a second feedback electrode disposed below the first plate. It may include an electrode.

When the feedback voltage V _F is applied to one side of the liquid lens 28 , the capacitance measuring circuit 54 connected to the other side may measure the capacitance between one side and the other side of the liquid lens 28 . Depending on the embodiment, the capacitance measurement circuit 54 may include various components. The change in capacitance caused by the movement and change of the interface 30 within the liquid lens 28 may be in a small range of several pF to several tens of pF.

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 feedback circuit 50 transmits calculated or measured information to the voltage control circuit 40 , and the voltage control circuit 40 may adjust a voltage in response to the information. The information calculated or measured by the feedback circuit may be a voltage or a capacitance value.

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 in response to the calculated information. In this case, the calculated information may be a voltage or a capacitance value.

6 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 a driving voltage is applied to the individual electrodes L1, L2, L3, and L4 of the liquid lens 28. do.

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.

7 illustrates the electrode structure of the liquid lens. Specifically, (a) describes the electrode arrangement on both sides (upper and lower) of the liquid lens 28 (refer to FIG. 3), and (b) illustrates a method of measuring the capacitance between electrodes disposed on both sides of the liquid lens. Explain.

Referring first to (a), one side of the liquid lens has four individual electrodes L1, L2, L3, and L4 that supply voltage to the periphery of the cavity. In addition, at one side of the liquid lens, there is at least one feedback electrode (F1a, F2a, F3a, F4a) between the four individual electrodes (L1, L2, L3, L4). According to an embodiment, there may be only one feedback electrode F1 in the liquid lens. Also, the number of individual electrodes and the number of feedback electrodes may be different. However, it is easier to measure the movement and shape of the interface 30 when the feedback electrode has the same angular distance with respect to the cavity or is symmetrical or disposed at four corners.

Similar to one side of the liquid lens, at least one feedback electrode F1b, F2b, F3b, and F4b may be provided on the other side of the liquid lens on which the common electrode C0 is disposed. The feedback electrodes F1b, F2b, F3b, and F4b disposed on the other side of the liquid lens may be disposed to correspond to the feedback electrodes F1a, F2a, F3a, F4a disposed on one side. Also, the number of the feedback electrodes F1b, F2b, F3b, and F4b disposed on the other side of the liquid lens may be the same as the number of the feedback electrodes F1a, F2a, F3a, F4a disposed on one side of the liquid lens.

Also, referring to (b), an example of a method of measuring the capacitance corresponding to the interface 30 of the liquid lens will be described. As shown in (a), a plurality of feedback electrodes (F1a, F2a, F3a, F4a, F1b, F2b, F3b, F4b) are disposed on both sides of the liquid lens, so that the capacitance can be measured in a desired direction. For example, the capacitance between the two feedback electrodes F1a and F2b disposed at positions corresponding to both sides of the liquid lens may be measured. Also, the capacitance between the two feedback electrodes F1a and F2a disposed on one side of the liquid lens may be measured. Also, the capacitance between the two feedback electrodes F1b and F3b disposed on the other side of the liquid lens may be measured. This capacitance measurement can be selectively made by disposing a switching element between the feedback circuit 50 and the liquid lens 28 . Measurement of capacitance in various directions and methods helps to more accurately understand the characteristics of the interface 30 in the liquid lens (eg, change in the position, movement, or shape of the interface according to the supplied driving voltage). This can also aid in lens calibration, which is required to understand the properties of liquid lenses and to correct distortion for more precise control.

Even while the camera device and the liquid lens mounted on the optical device are being driven, the feedback circuit 50 may measure the capacitance that changes according to the position, movement, or shape of the interface 30 . When the position, movement, or shape of the interface 30 is recognized through the capacitance, it is transmitted to the voltage control circuit 40 to adjust the driving voltage when distortion occurs.

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

As shown, when the feedback voltage V _F transmitted from the feedback voltage control circuit 52 is applied to one of the feedback electrodes F1a disposed in the liquid lens, the capacitance measurement circuit connected to the other F1b ( 54 ) measures the capacitance between the two feedback electrodes F1a and F1b to recognize the state of the interface 30 .

When the feedback voltage V _F is applied and the first switch SW1 in the feedback voltage control circuit 52 is connected, the amount of charge Q on the interface 30 is proportional to the amount of change of the feedback voltage ΔV _F on the interface 30 ) multiplied by the capacitance (C). When the first switch SW1 is connected, the charge Q may move to the measurement capacitor Cap-m.

Thereafter, when a ground voltage is applied instead of the feedback voltage V _F , the first switch SW1 is turned off and the second switch SW1 is turned on, the charge moved to the measurement capacitor Cap-m can be moved to on-chip capacitors (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 _F of 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 measurement 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.

Fig. 9 explains the connection part of the liquid lens.

As shown, the connection part connecting the liquid lens and the driving circuit (eg, control circuit) uses a flexible printed circuit board (FPCB) to supply voltage to each of the individual electrodes L1, L2, L3, and L4. The first connector 142 and the second connector 144 for supplying the common voltage C0 using the flexible printed circuit board (FPCB) may be included. In addition, a plurality of feedback electrodes F1a, F2a, F3a, F4a, F1b, F2b, F3b, F4b for measuring the capacitance of the interface 30 (refer to FIG. 7 ) are provided at the first connection part 142 and the second connection part 144 . ) may further include terminals for connecting the feedback voltage control circuit 52 and the capacitance measurement circuit 54 (refer to FIG. 5 ). The feedback voltage control circuit 52 is for supplying the feedback voltage V _F . , the capacitance measuring circuit 54 (refer to FIG. 5 ) is for measuring the capacitance of the interface 30 .

The first connector 142 may be electrically connected to the four individual electrodes L1, L2, L3, and L4 and the feedback electrodes F1a, F2a, F3a, and F4a. The first connector may be connected to the four feedback electrodes. Meanwhile, the second connection part 144 is for applying a common voltage (eg, a ground voltage or 0V or a common DC or a common AC), and may be electrically connected to the feedback electrodes F1b, F2b, F3b, and F4b. The second connector may be connected to the four feedback electrodes. The second connector may have a structure corresponding to that of the first connector 42 . The terminals disposed on the first connector 142 and the second connector 144 and connected to the plurality of electrodes are the same with respect to the cavity of the liquid lens. It can be located on any street.

Depending on the embodiment, the liquid lens may have 4, 8, or more than 8 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.

Meanwhile, according to the embodiment, in FIG. 9 , the connection parts 142 and 144 have been described as having an open structure on one side, but have a structure connected to surround four surfaces of the liquid lens without an open area. may be

Fig. 10 illustrates the connection of the liquid lens and the control circuit. In particular, FIG. 10 describes the connection of the control circuit described with reference to FIG. 5 in more detail.

As shown, the liquid lens 28 is connected to a voltage control circuit 40 that supplies driving voltages to individual and common electrodes of the liquid lens 28, and the capacitance measurement circuit 50 is connected to the liquid lens ( 28) It can be connected to two electrodes whose capacitance is to be measured. The two electrodes for measuring the capacitance in the liquid lens 28 may be selected as described above with reference to FIG. 7 .

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. 11 explains the timing of the switching elements shown in Fig. 10 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. 11 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 third switch SW13 is turned on to connect the ground voltage SW3 to the measuring capacitor in the capacitance measuring circuit 50 to discharge charges.

After that, when the first switch SW11 is connected, the accumulated charge due to the capacitance of the liquid lens moves to the measuring capacitor, and after turning off the first switch SW11, the first capacitance in the measuring capacitor is A value can be sensed (1 ^st cap sensing window).

Thereafter, the switching element SW_V is turned on to apply the voltage VIN, and the second switch SW12 is turned on. At this time, the charges accumulated in the capacitor for measurement 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 in the measurement capacitor (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. 8 .

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.

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 In addition, 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 on 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 network-connected computer systems, 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 (11)

a liquid lens comprising a common electrode, a first feedback electrode, a plurality of individual electrodes, and a second feedback 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 first feedback electrode and the second feedback electrode of the liquid lens;
wherein the second feedback electrode is disposed between the plurality of individual electrodes, and the first feedback electrode is disposed at a position corresponding to the second feedback electrode. delete According to claim 1,
and a feedback voltage control circuit configured to transmit a feedback voltage to either one of the first and second feedback electrodes to measure the capacitance between the first and second feedback electrodes. , liquid lens control circuit. According to claim 1,
transferring information on the capacitance calculated by the capacitance measuring circuit to the voltage control circuit;
and the voltage control circuit adjusts the voltage supplied to the liquid lens in response to the calculated information. 5. The method of claim 4,
and the information calculated by the capacitance measuring circuit is a voltage or a capacitance value. 4. The method of claim 3,
and the voltage supplied to the liquid lens is at a level that is at least 2 to 10 times greater than the feedback voltage. 7. The method of claim 6,
The feedback voltage has a range of 1.5-5V, and the voltage supplied to the liquid lens has a range of 10-80V, a liquid lens control circuit. a first plate including a cavity in which a conductive liquid and a non-conductive liquid are disposed;
a first electrode disposed on the first plate;
a plurality of second electrodes disposed under the first plate;
a second plate disposed on the first plate;
a third plate disposed under the first plate;
a first feedback electrode disposed adjacent to the first electrode; and
a second feedback electrode disposed between the plurality of second electrodes;
Containing, a liquid lens module. 9. The method of claim 8,
a first substrate for transmitting a voltage to the first electrode or a feedback voltage to the first feedback electrode; and
A liquid lens module, further comprising a second substrate for transmitting a voltage to the second electrode or a feedback voltage to the second feedback electrode. 9. The method of claim 8,
The first electrode is a common electrode, the second electrode is an individual electrode,
The number of the second feedback electrodes and the number of the second electrodes are the same, liquid lens module. 9. The method of claim 8,
The liquid lens module further comprising an insulating film covering the plurality of second electrodes and the second feedback electrode on the cavity.

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