KR20180114822A - Control circuit of liquid lens, camera module and controlling method for liquid lens - Google Patents

Abstract

The present invention provides a method and a device for accurately measuring movement and a change of an interface. According to an embodiment of the present invention, a controlling method of a liquid lens comprises the following steps of: grounding a common electrode of a liquid lens, and applying voltage to one among a plurality of individual electrodes of the liquid lens; blocking so as not to apply the voltage to the common electrode of the liquid lens; electrically connecting between a capacitance measuring circuit and the liquid lens; measuring the voltage of both ends of a capacitor of the capacitance measuring circuit; and controlling driving voltage by using the measured voltage of the both ends of the capacitor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid lens control circuit, a camera module,

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

Users of portable devices have high resolution and are small in size and have a variety of functions such as zoom-in / zoom-out, auto-focusing (AF), anti- Stabilizer, OIS) function, etc.). Such a photographing function can be realized by a method of directly moving the lens by combining a plurality of lenses, but when the number of lenses is increased, the size of the optical device can be increased. The autofocus and camera shake correction functions are performed by moving a plurality of lens modules fixed to a lens holder and having optical axes aligned in a vertical direction of an optical axis or an optical axis or by tilting, Device is used. However, since the lens driving device consumes a large amount of power, it is necessary to add a cover glass separately from the camera module in order to protect the lens module. Therefore, liquid lenses that perform autofocus and camera shake correction functions by electrically adjusting the curvature of the interface between two liquids are being studied.

The present invention provides a feedback circuit capable of recognizing the 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 distance using electric energy, 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.

The present invention also provides a feedback circuit capable of measuring a change in capacitance in a capacitor having a very small capacitance (for example, 200 to 500 pF or less) but a very high voltage (for example, 30 to 50 V or more) .

The present invention also provides a method of measuring a capacitance between electrodes disposed in a liquid lens capable of adjusting a focal length, the method comprising the steps of: measuring a capacitance between a common electrode and a ground electrode; It is possible to provide an apparatus and a method for measuring capacitance by floating a common electrode at a falling edge.

In addition, the present invention can directly recognize the movement and shape of the interface through the change of the capacitance of the interface without converting the optical signal passing through the interface into the image and recognizing the movement and shape of the interface of the liquid lens, The performance and operation of the liquid lens can be more accurately controlled.

Further, the present invention can recognize the movement and shape of the interface in the liquid lens, and it is possible to correct the lens distortion in the lens assembly including the liquid lens and the solid lens, or to control the lens assembly, .

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

A control circuit of a liquid lens according to an embodiment of the present invention includes: a liquid lens including a plurality of discrete 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 and the plurality of individual electrodes of the liquid lens; And a first switch disposed between the capacitance measuring circuit and the liquid lens, wherein one end of the first switch can be electrically connected to the liquid lens and the voltage control circuit.

Further, the capacitance measuring circuit may include a reference capacitor, and the capacitance of the liquid lens may be calculated using the reference capacitor.

The other end of the first switch may be connected to the capacitance measuring circuit.

The capacitance measuring circuit may be connected to the common electrode.

The capacitance measuring circuit may be connected to at least any one of the plurality of individual electrodes.

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 discrete 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.

Further, 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 by using the calculated information.

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

In addition, the common electrode may be floating during a period in which the first switch is turned ON.

Further, the liquid lens control circuit may further include a third switch disposed between the voltage control circuit and the first switch, and between the voltage control circuit and the liquid lens, and the third switch may supply a voltage to the common electrode , And the capacitance measurement circuit may be turned off while measuring the capacitance.

A camera module according to another embodiment of the present invention includes: a liquid lens including a plurality of discrete 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 and the plurality of individual electrodes of the liquid lens; A first switch disposed between the capacitance measuring circuit and the liquid lens; A lens assembly including at least one solid lens disposed above or below the liquid lens; And an image sensor disposed under the lens assembly, wherein one end of the first switch is electrically connected to the liquid lens and the voltage control circuit, and the liquid lens includes a cavity in which the conductive liquid and the nonconductive 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 discrete electrodes can be disposed under the first plate.

According to another aspect of the present invention, there is provided a liquid lens control method including: a common electrode of a liquid lens connected to a ground; a voltage being applied to individual electrodes of the liquid lens; Turning on a first switch disposed between the capacitance measuring circuit and the liquid lens; Measuring a voltage across the reference capacitor of the capacitance measurement circuit; And calculating a capacitance between the common electrode and the individual electrode using the measured value of the voltage across the reference capacitor.

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

Further, the liquid lens control method is characterized in that at least a part 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 measurement circuit Step < / RTI >

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And can be understood and understood.

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

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

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

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

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

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

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The embodiments are to be considered in all aspects as illustrative and not restrictive, and the invention is not limited thereto. It is to be understood, however, that the embodiments are not intended to be limited to the particular forms disclosed, but are to include all modifications, equivalents, and alternatives falling within the spirit and scope of the embodiments.

The terms "first "," second ", and the like can be used to describe various components, but the components should not be limited by the terms. The terms are used for the purpose of distinguishing one component from another. In addition, terms specifically defined in consideration of the constitution and operation of the embodiment are only intended to illustrate the embodiments and do not limit the scope of the embodiments.

In the description of the embodiments, when it is described as being formed on the "upper" or "on or under" of each element, the upper or lower (on or under Quot; includes both that the two elements are in direct contact with each other or that one or more other elements are indirectly formed between the two elements. Also, when expressed as "on" or "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

It is also to be understood that the terms "top / top / top" and "bottom / bottom / bottom", as used below, do not necessarily imply nor imply any physical or logical relationship or order between such entities or elements, And may be used to distinguish one entity or element from another entity or element.

1 illustrates an example of a camera apparatus. As shown, the camera module may include a lens assembly 22 and an image sensor. At least one solid lens may be disposed on the top or bottom of the lens assembly. The lens assembly 22 may include a liquid lens whose focal length is adjusted corresponding to the applied voltage. The camera module includes a lens assembly (22) including a plurality of lenses including a first lens whose focal length is adjusted corresponding to a drive voltage applied between a common terminal and a plurality of individual terminals, and a drive voltage And an image sensor 26 that is arranged on the lens assembly 22 and converts the light transmitted through the lens assembly 22 into an electrical signal and is disposed at the bottom of the lens assembly have.

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

2, 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, . ≪ / RTI > 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 structure of the illustrated lens assembly 22 is only one example, and the structure of the lens assembly 22 may vary according to the 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 is disposed between the first lens unit 100 100, or one of the first lens unit 100 and the second lens unit 200 may be omitted. The configuration of the control circuit 24 can be designed differently according to the specifications required for the camera apparatus. In particular, when the magnitude of the operating voltage applied to the lens assembly 22 is reduced, the control circuit 24 can be implemented as a single chip. As a result, the size of the camera device mounted on the portable device can be further reduced.

2 illustrates an example of the lens assembly 22 included in the camera apparatus.

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 structure of the illustrated lens assembly 22 is only one example, and the structure of the lens assembly 22 may vary according to the 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 is disposed between the first lens unit 100 100, or one of the first lens unit 100 and 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 region where light enters from the outside of the lens assembly. The first lens unit 100 may be provided with at least one lens, or two or more lenses may be aligned with respect to the central axis PL to form an optical system.

The first lens unit 100 and the second lens unit 200 may be mounted on the lens holder 400. At this time, a through hole is formed in the lens holder 400, and the first lens unit 100 and the second lens unit 200 may be disposed in the through hole. 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 outside the lens holder 400 and be exposed to the outside. When the solid lens is exposed, the lens surface may be damaged due to exposure to the outside. If the lens surface is damaged, the image quality of the image taken by the camera module may be deteriorated. A method of disposing a cover glass or forming a coating layer or constructing a solid lens 100 with a wear resistant material to prevent surface damage may be applied to prevent or suppress surface damage of the solid lens 110. [

The second lens unit 200 is disposed behind the first lens unit 100 and the liquid lens unit 300 and the light incident from the outside to the first lens unit 100 passes through the liquid lens unit 300 So that it can be incident on the second lens unit 200. The second lens unit 200 may be disposed in the through hole formed in the lens holder 400 so as to be spaced apart from the first lens unit 100.

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

 The liquid lens unit 300 may be disposed between the first lens unit 100 and the second lens unit 200 and may be inserted into the insertion port 410 of the lens holder 400. The insertion port 410 may be formed by opening a part of the side surface of the lens holder. That is, the liquid lens may be inserted through the insertion port 410 on the side surface of the holder. The liquid lens unit 300 may also be aligned with respect to the center 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 portion 100 is transmitted, and may include at least a part of the liquid. For example, the lens region 310 may include two types, that is, a conductive liquid and a non-conductive liquid, and the conductive liquid and the non-conductive liquid may form an interface without intermixing with each other. The interface between the conductive liquid and the non-conductive liquid may be 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 deformation and curvature change of the interface are controlled, the liquid lens unit 300 and the camera module including the liquid lens unit 300 can perform an auto focusing function, an image stabilization function, and the like.

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

First, referring to (a), a lens 28 whose focal length is adjusted in response to a driving voltage is connected to a voltage terminal (not shown) through individual terminals L1, L2, L3 and L4 arranged in four different directions . 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. Four individual terminals may be arranged at four corners of the liquid lens, respectively. When a voltage is applied through the individual terminals L1, L2, L3 and L4, the applied voltage is placed in the lens region 310 by a driving voltage formed by interaction with a voltage applied to the common terminal C0 The interface between the conductive liquid and the non-conductive liquid may be deformed.

Referring to FIG. 2B, the lens 28 receives an operation voltage from one of the individual terminals L1, L2, L3 and L4, and the other end thereof is connected to a plurality of capacitors 30). 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 above-mentioned liquid lens of the liquid lens may be referred to as an electrode sector or a sub electrode in this specification.

4 illustrates the structure of the liquid lens.

As shown, the liquid lens 28 may comprise a liquid, a first plate, and an electrode. The liquids 122 and 124 contained in the liquid lens 28 may include a conductive liquid and a nonconductive liquid. The first plate may include a cavity 150 or a hole in which the conductive liquid and the nonconductive 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 on 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. The liquid lens 28 may further include a third plate 116 that may be disposed below (upper) the electrodes 132, 134. As shown, one embodiment of the 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 that supplies a voltage to the liquid lens 28. The 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 the third plate may not be disposed on the upper surface or the lower surface of the liquid lens corner, May be thinner than the center portion. The 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, the conductive liquid 122 and the non-conductive liquid 124, and the curvature and shape of the interface 130 formed by the two liquids And can be adjusted by the supplied driving voltage. The driving voltage supplied to the liquid lens 28 may be transmitted through the connection part 500. The connection portion may include at least one of the first substrate 142 and the second substrate 144. The second substrate 144 may transmit a voltage to each of the plurality of individual terminals when the connection portion includes the first substrate 142 and the second substrate 144 and the first substrate 142 may transmit a voltage to the common terminal . 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 arranged or exposed at the respective corners of the liquid lens 28. [

The liquid lens 28 also includes a third plate 116 comprising a transparent material and a second plate 112 positioned between the second plate 112 and the third plate 116 and the second plate 112, And a first plate 114 that includes regions.

The liquid lens 28 may also include a cavity 150 determined by the third plate 116, the second plate 112, and the opening area of the first plate 114. Here, the cavity 150 can be filled with two liquids 122, 124 of different properties (e.g., conductive liquid and nonconductive liquid), and between the two liquids 122, 124 of different properties, May be formed.

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 at the top and bottom of the first plate 114, . ≪ / RTI > The first plate 114 may further include an insulating layer 118 including an inclined surface and disposed on an inclined surface. The liquid having conductivity can contact the insulating layer. Here, the insulating layer 118 covers one electrode (e.g., the second electrode 134) of the two electrodes 132 and 134 and covers a part of the other electrode (e.g., the first electrode 132) Or exposed to provide electrical energy to the conductive liquid (e.g., 122). Here, the first electrode 132 includes at least one electrode sector (e.g., C0), and the second electrode 134 includes two or more electrode sectors (e.g., L1, L2, L3, and L4 in FIG. 4) can do. For example, the second electrode 134 may include a plurality of electrode sectors sequentially disposed along the clockwise direction about the optical axis. The electrode sector may be referred to as a sub-electrode or a terminal of a liquid lens.

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

Fig. 5 illustrates the change of the interface in the liquid lens. Specifically, (a) to (c) illustrate the movement of the interfaces 30a, 30b, and 30c that may occur when a 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 can maintain a shape close to a circle. The horizontal distance LH of the interface and the vertical distance LV of the interface are substantially equal to each other and the movement of the interface 30a (for example, the inclination angle) is balanced. In this case, the capacitance value of the interface 30a measured through four different individual electrodes L1, L2, L3, and L4 can be measured to be substantially the same.

The voltage applied to the first discrete electrode L1 and the third discrete electrode L3 of the liquid lens 28 is applied to the second discrete electrode L2 and the fourth discrete electrode L4 The case where the voltage is higher than the applied voltage will be described. In this case, since the pulling or pushing force of the interface 30b is different in horizontal or vertical direction, the horizontal distance LH of the interface as viewed from the upper face can be made shorter than the vertical distance LV of the interface as viewed from the upper face . When the voltages applied to the second discrete electrode L2 and the fourth discrete electrode L4 are lower than those of the first discrete electrode L1 and the third discrete electrode L3, The inclination angle of the interface 30b of the liquid lens 28 in the individual electrode L4 is smaller than the inclination angle of the interface 30b of the liquid lens 28 in the first individual electrode L1 and the third individual electrode L3 The vertical distance LV is longer than the horizontal distance LH in the three-dimensional view. In this case, the capacitance values of the interface 30a measured through four different individual electrodes L1, L2, L3 and L4 may be different from each other. On the other hand, since the interface 30b has symmetrically changed the interface 30b, the capacitance value of the interface 30a measured through four different individual electrodes L1, L2, L3 and L4 can be symmetrical. In this case, the capacitance values of L1 and L3 are the same, and the capacitance values of L2 and L4 are the same.

The voltage applied to the first individual electrode L1 and the third individual electrode L3 of the liquid lens 28 and the voltage applied to the second individual electrode L2 and the fourth individual electrode L4, The vertical distance LV of the interface at the interface as viewed from the top surface can be made shorter than the horizontal distance LH). the interface 30c may have different capacitances of the interface 30c measured through four different individual electrodes L1, L2, L3, and L4, as in the case of FIG. On the other hand, since the interface 30c is symmetrically changed in the interface 30b, the capacitance value of the interface 30a measured through four different individual electrodes L1, L2, L3 and L4 may be symmetrical. In this case, the capacitance values of L1 and L3 are the same, and the capacitance values of L2 and L4 are the same.

The capacitances measured at the interfaces 30a, 30b, and 30c shown in FIGS. 3A, 3B, and 3C are different from each other, It is possible to more accurately and precisely measure how the interfaces 30a, 30b, and 30c are moved according to the voltage applied to the electrode L4.

While the liquid lens 28 has been described as including four separate electrodes in the above example, it is contemplated that the liquid lens 28 may have 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 movement can be measured more accurately.

6 illustrates a control circuit interlocked with a liquid lens.

As shown, the liquid lens 28 includes four individual electrodes L1, L2, L3, L4 and one common electrode C0 (see FIG. 3). The voltage control circuit 40 can generate and supply the voltages VL1, VL2, VL3, VL4, VC0 applied to the four individual electrodes L1, L2, L3, L4 and one common electrode C0. 4 and 5, the 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).

The capacitance measurement circuit 50 is for measuring or calculating the position, shape or motion of the interface 30 in the liquid lens 28. [ The position, shape or motion of the liquid lens 28 interface 30 can be measured using capacitances as described in FIG. At least one individual electrode L1, L2, L3, L4 included in the liquid lens 28 and a common electrode may be used to measure the capacitance between the first electrode and the second electrode of the liquid lens 28 .

The voltage control circuit 40 applies voltages VL1, VL2, VL3, VL4 and VC0 of at least 0V to 80V to the four individual electrodes L1, L2, L3 and L4 and the common electrode C0 at the same time point Or at another point in time. 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, In accordance with the timing at which it is generated.

As shown, the interface 30 of the liquid lens 28 has voltages VL1, VL2, VL3, VL4, and VC0 that are transmitted to the plurality of discrete electrodes L1, L2, L3, and L4 and the common electrode C0 And can be controlled corresponding to the driving voltage to be formed. A change in the movement, position, or shape of the interface 30 in the liquid lens 28 is determined by the voltage of the first to fourth voltages VL1, VL2, VL3, VL4 and the voltage VC0 applied to the common electrode C0 It can happen by car.

The change in the movement, position, or shape of the interface 30 in the liquid lens 28 due to the voltage difference between the first to fourth voltages VL1, VL2, VL3, and VL4 and the voltage VC0 of the common electrode C0 A change in capacitance may occur. Movement of interface (30) in liquid lens (28). The change in capacitance caused by the change in position, or shape, can be in the range of a few pF to a few tens 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 set such that the ground voltage GND, 0V is applied to the common electrode C0, The electrode C0 can be measured by floating. More specifically, the first to fourth voltages VL1, VL2, VL3, and VL3 applied to one of the first to fourth individual electrodes L1, L2, L3, and L4 are applied to the common electrode C0, The capacitance can be measured using a change in the voltage applied to the electrode when the voltage VL4 is falling edge or rising edge falling from the high voltage (e.g., 10 V to 80 V) to the ground voltage (0 V). (Ground floating edge measurement)

The capacitance measurement circuit 50 connected to the common electrode C0 side in the liquid lens 28 can measure the capacitance between the individual electrode and the common electrode in the liquid lens 28. [ According to an embodiment, the capacitance measurement circuit 54 may comprise various components.

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

As another example, the capacitance measuring circuit 54 for measuring a small capacitance of several pF to several tens of pF can calculate the ratio of a capacitor having a known large value to a capacitor having a small value to be measured, The capacitance of the interface 30 may be measured through a method of discharging.

The capacitance measurement circuit 50 transmits the calculated or measured information to the voltage control circuit 40 and the voltage control circuit 40 can adjust the voltages VL1, VL2, VL3, VL4, VC0 in accordance with the information have. The information calculated or measured by the capacitance measuring circuit may be a voltage or a capacitance value. The information calculated by the capacitance measuring circuit is transmitted to the voltage control circuit, and the voltage control circuit can constitute a liquid lens control circuit for adjusting the driving voltage by using the calculated information.

Fig. 7 illustrates an example of the capacitance measuring circuit. The capacitance measurement circuit shown in Fig. 8 is presented as an example, and may include various components according to the embodiment.

As shown in the figure, when the voltage transmitted from the voltage control circuit 40 is applied to one of the electrodes L1 arranged in the liquid lens, the capacitance measuring circuit 54 connected to the other one C0 is connected to the two electrodes L1 , C0) to determine the state of the interface (30).

When the voltage VL1 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 proportional to the amount of change of the voltage DELTA VL1 and the capacitance C of the interface 30 ). ≪ / RTI > When the first switch SW1 is connected, the charge Q can move to the reference capacitor Cap-m.

Thereafter, when the first switch SW1 is turned off and the second switch SW1 is turned on at the falling edge where the voltage VL1 falls to the ground voltage, the reference capacitor Cap- Charge to the on-chip capacitor (Cap-on). At this time, the amount of charge Q moving to the on-chip capacitor Cap-on may be equal to the amount of change of the feedback voltage DELTA VL1 multiplied by the capacitance of the on-chip capacitor Cap-on.

The ratio of the number of coupling by the capacitance C of the interface 30 to the number of coupling by the on-chip capacitor Cap-on is adjusted so that the total amount of charges accumulated in the reference capacitor Cap- 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 can be measured.

The configuration of the capacitance measuring circuit 54 may vary according to the embodiment, and the operation and the control method may be different from each other. Here, the capacitance measurement circuit 54 can be designed to measure a change of several pF to 200 pF.

The configuration of the circuit for measuring the capacitance may be variously implemented according to the embodiment. For example, a circuit that calculates the capacitance based on the resonance frequency using the LC series resonance for the common electrode can be used. However, in the case of using the LC series resonance, it is necessary to apply the waveform for each frequency in order to find the resonance frequency, so it may take time to calculate the capacitance, and the interface of the liquid lens may be affected thereby. However, the above-described capacitance measuring circuit 54 is a capacitance measuring circuit using a switched capacitor. Switched capacitors can include two switches and a capacitor, which can be used to control the average current flowing through them. The average resistance can be inversely proportional to the capacitor capacitance and the switch operating frequency. When the capacitance of a liquid lens is measured using a switched capacitor, the capacitance can be measured at a very high speed (for example, several tens of ns).

In addition, a switched capacitor circuit, which can be constituted by only a capacitor and a switch, is higher than a LC series resonant circuit in which a resistor, an inductor, and a capacitor must be included in a circuit for measuring a capacitance, . One end of the first switch may be electrically connected to the liquid lens and the voltage control circuit.

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

As shown, the control circuit includes a voltage control circuit 40 and a capacitance measurement circuit 50, which may be connected to the liquid lens 28. The voltage control circuit 40 can selectively transmit one of the high voltage (e.g., 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 measurement circuit 50 may be connected to the common electrode C0 side. The electrostatic capacitance measuring circuit 50 can measure the capacitance of the liquid lens 28 by connecting the first switch SW1 to be described later to the electrostatic capacity measuring circuit 50, Lt; / RTI > The capacitance measurement circuit 50 may further include components such as a capacitor in addition to the comparator so that the amount of charge transferred from the capacitor of the liquid lens 28 can be measured.

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

The ground voltage GND is applied to the common electrode C0 before the capacitance of the liquid lens 28 is measured. Thereafter, when the first switch SW1 is connected, the second switch SW0 of the voltage control circuit 40 is turned off to make the common electrode C0 floating. The second switch SW0 is a switch for applying the ground voltage GND to the common electrode C0. Thereafter, when the first switch SW1 is connected and the voltage VL1 applied to the individual electrode L1 to be measured is changed, the charges stored in the capacitor of the liquid lens 28 (e.g., Q (charge quantity) = DELTA VL1 x C (capacitance of the liquid lens)) to the capacitance measurement circuit 50.

Fig. 9 illustrates the operation of the control circuit of Fig.

As shown in the figure, a plurality of individual electrodes L1, L2, L3, and L4 and a common electrode C0 of the liquid lens are provided with a high voltage (e.g., 70V, 35V) and a ground voltage E.g., 0 V) may be applied.

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, when the second switch SW0 of the voltage control circuit 40 is connected. The voltage applied to the individual electrodes L1, L2, L3 and L4 in a state in which the first switch SW1 in the capacitance measuring circuit 50 is connected (ON) is changed from a high voltage to a ground voltage, Measurements can be made.

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

On the other hand, for the measurement of the capacitance, the voltage control circuit can rotate the voltages applied to the plurality of individual electrodes included in the liquid lens in clockwise or counterclockwise directions and transmit them to different points in time.

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

As shown, the control circuit includes a voltage control circuit 40 and a capacitance measurement circuit 50, which may be connected to the liquid lens 28. The voltage control circuit 40 can selectively transmit one of the high voltage (e.g., 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 measurement circuit 50 may be connected to the common electrode C0 side. The electrostatic capacitance measuring circuit 50 can measure the capacitance of the liquid lens 28 by connecting the first switch SW1 to be described later to the electrostatic capacity measuring circuit 50, Lt; / RTI > The capacitance measurement circuit 50 may further include components such as a capacitor in addition to the comparator so that the amount of charge transferred from the capacitor of the liquid lens 28 can be measured.

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

The second switch SW3 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 can control the floating state in the process of measuring the capacitance by the capacitance measuring circuit 50 connected to the common electrode C0. Further, the switch unit SW3, which is connected independently, may be effective to lower the breakdown voltage of the switching device, rather than controlling the floating state using the switch in the voltage control circuit 40. [

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

11 illustrates the operation of the control circuit of Fig.

As shown in the figure, a plurality of individual electrodes L1, L2, L3, and L4 and a common electrode C0 of the liquid lens are provided with a high voltage (e.g., 70V, 35V) and a ground voltage E.g., 0 V) may be applied.

The capacitance can be measured when the ground voltage is applied to the common electrode C0, that is, the voltage control circuit 40 and the third switch SW3 can be connected. After the third switch SW3 is connected and the ground voltage GND is applied to the common electrode C0, the third switch SW3 is turned off to float the common electrode C0. The voltage applied to the individual electrodes L1, L2, L3 and L4 in the state in which the first switch SW1 is connected to the capacitance measurement circuit 50 in a state in which the common electrode C0 is floated is at a high voltage If the falling edge falls to ground voltage, the amount of charge can be shifted.

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

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

12 illustrates the connection of the liquid lens and the control circuit. In particular, Fig. 12 illustrates 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 for supplying a voltage to the individual electrodes and the common electrode of the liquid lens 28, and the capacitance measurement circuit 50 is connected to the liquid lens 28 ) Of the two electrodes. The two electrodes on both sides of the position where the capacitance of the liquid lens 28 is to be measured, i.e., the capacitance, can be selected as described in FIGS. 8 to 11 described above.

On the other hand, the voltage control circuit 40 and the capacitance measurement circuit 50 are connected through the switching element SW_V. The switching element SW_V is turned ON at the time when the capacitance in the liquid lens 28 is to be measured and the input voltage VIN is applied to the capacitance measurement circuit 50 before being boosted by the voltage control circuit 40. [ .

Fig. 13 illustrates 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 timing of the switching circuit described in Fig. 12 will be mainly described.

As shown in the figure, 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. 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 the charge.

Then, when the fifth switch SW11 is connected, the charge accumulated due to the capacitance of the liquid lens moves to the reference capacitor Cap-m, the fifth switch SW11 is turned off, and the reference capacitor Cap -m) to sense the value of the first capacitance (1st cap sensing window).

Thereafter, the switching element SW_V is turned on, the voltage VIN is applied, and the sixth switch SW12 is turned on. At this time, the charge accumulated in the reference capacitor Cap-m can be moved. Then, the value of the second capacitance can be sensed in the reference capacitor Cap-m (second cap sensing window) while the switching element SW_V and the second switch SW12 are turned off.

Hereinafter, the method of recognizing the capacitance of the liquid lens may be the same as that described in Fig.

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

As described above, in the method of controlling the liquid lens, the common electrode of the liquid lens is connected to the ground, the voltage is applied to the individual electrodes of the liquid lens, and charge is accumulated between the common electrode and the individual electrode, And a step of measuring a voltage across the reference capacitor of the capacitance measurement circuit. Then, the capacitance between the common electrode and the individual electrode can be calculated using the measured value of the voltage across the reference capacitor.

According to an embodiment, a method of controlling a liquid lens includes the steps of: connecting a common electrode of the liquid lens and one of the individual electrodes to the ground; applying a voltage to the other of the common electrode and the individual electrode of the liquid lens; Measuring a voltage across the reference capacitor of the capacitance measuring circuit; measuring the voltage across the reference capacitor; measuring the voltage across the reference capacitor; measuring the voltage across the reference capacitor; And calculating a capacitance between the electrodes.

The above-described liquid lens 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 a front surface or a rear surface of the liquid lens, an image sensor that converts an optical signal transmitted through the lens assembly into an electrical signal, And a control circuit for supplying a driving voltage to the liquid lens.

While only a few have been described above with respect to the embodiments, various other forms of implementation are possible. The technical contents of the embodiments described above may be combined in various forms other than the mutually incompatible technologies, and may be implemented in a new embodiment through the same.

An optical device (optical instrument) including the camera module described above can 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, photometer devices, polarimeter devices, spectrometer devices, reflectometer devices, autocollimator devices, lens meter devices, The embodiment of the present invention can be applied to an optical device that can be used. In addition, the optical device can be implemented as a portable device such as a smart phone, a notebook computer, and a tablet computer. Such an optical apparatus may include a camera module, a display unit for outputting an image, and a main body housing for mounting the camera module and the display unit. The optical device may further include a memory unit in which a communication module capable of communicating with other devices can be mounted on the body housing and can store data.

The method according to the above-described embodiments may be implemented 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 a ROM, a RAM, a CD- , Floppy disks, optical data storage devices, and the like.

The computer readable recording medium may be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner. And, functional program, code, and code segments for implementing the above-described method can be easily inferred by programmers in the technical field to which the embodiment belongs.

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

Claims (15)

A plate including a cavity in which a conductive liquid and a non-conductive liquid are disposed;
A plurality of discrete electrodes disposed on the plate;
A common electrode disposed under the plate;
And a liquid lens
And a voltage control circuit for applying a driving voltage to the liquid lens,
Applying a voltage to any one of the plurality of individual electrodes of the liquid lens by grounding the common electrode of the liquid lens;
Blocking the common electrode of the liquid lens from being applied with a voltage;
Electrically connecting the capacitance measuring circuit and the liquid lens;
Measuring a voltage across a capacitor of the capacitance measurement circuit;
And controlling the driving voltage using the measured voltage across the capacitor. The method according to claim 1,
Calculating capacitances between the common electrode and any one of the plurality of discrete electrodes using the measured voltage across the capacitors of the capacitance measurement circuit;
Controlling the driving voltage by using the calculated capacitance;
And a liquid lens. 3. The method of claim 2,
Wherein the capacitance measuring circuit sequentially calculates the capacitances between each of the plurality of individual electrodes and the common electrode. 3. The method of claim 2,
And a first switch disposed between the voltage control circuit and the common electrode,
And the first switch is turned off so that a voltage is not applied to the common electrode of the liquid lens. 3. The method of claim 2,
And a second switch disposed between the liquid lens and the capacitance measurement circuit,
And the second switch is turned ON to electrically connect the capacitance measurement circuit and the liquid lens. 6. The method of claim 5,
Further comprising the step of transferring at least a portion of the accumulated charge to the reference capacitor between the step of turning on the second switch and the step of measuring the voltage across the reference capacitor of the capacitance measurement circuit, Control method. 6. The method of claim 5,
Wherein when the shape of the interface is changed by the drive voltage, a ground voltage is applied to the common electrode, and the common electrode is floating,
A liquid lens control unit for calculating the capacitance in a section in which the second switch is turned on and a voltage of at least one of the plurality of individual electrodes is changed from a first voltage to a second voltage lower than the first voltage, Way. 3. The method of claim 2,
And feeding back the capacitance calculated by the capacitance measurement circuit to the voltage control circuit. 6. The method of claim 5,
Wherein the second switch is off while the voltage control circuit supplies the drive voltage to operate the liquid lens. 6. The method of claim 5,
The voltage control circuit has a function of supplying a voltage to drive the liquid lens
And storing a charge for measuring the capacitance in the liquid lens. 6. The method of claim 5,
And the capacitance measurement circuit is connected to the common electrode. 6. The method of claim 5,
Wherein the voltage control circuit includes 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 discrete electrodes. 6. The method of claim 5,
Further comprising a first switch disposed between the voltage control circuit and the second switch and between the voltage control circuit and the liquid lens,
Wherein the first switch is turned on while supplying a voltage to the common electrode, and the capacitance measuring circuit is turned off while calculating the capacitance. A plate including a cavity in which a conductive liquid and a non-conductive liquid are disposed;
A plurality of discrete electrodes disposed on the plate;
A common electrode disposed under the plate;
A liquid lens;
A first lens unit disposed on the liquid lens;
A second lens unit disposed below the liquid lens;
And a printed circuit board on which an image sensor and a voltage control circuit electrically connected to the liquid lens are disposed,
Applying a voltage to any one of the plurality of individual electrodes of the liquid lens by grounding the common electrode of the liquid lens;
Blocking the common electrode of the liquid lens from being applied with a voltage;
Electrically connecting the capacitance measuring circuit and the liquid lens;
Measuring a voltage across the capacitor of the capacitance measurement circuit; And
Controlling the driving voltage using a voltage across the capacitor;
And a liquid lens. 15. The method of claim 14,
And calculating a capacitance between the common electrode and any one of the plurality of individual electrodes by using a voltage across the capacitor.

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