KR102372340B1 - Control circuit of liquid lens - Google Patents

Abstract

The present invention provides a liquid lens including a common electrode and a plurality of individual electrodes; a voltage generator generating a driving voltage for driving the liquid lens; and a first section in which the duty ratio of the driving voltage is changed when the Vrms value of the driving voltage applied between the common electrode and one of the plurality of individual electrodes is changed from the first Vrms value to the second Vrms value; A liquid having a second section having a duty ratio different from that of the first section, wherein a duty ratio of at least one of the first section or the second section is greater than a duty ratio in the section having the second Vrms value. A lens control circuit is provided.

Description

CONTROL CIRCUIT OF LIQUID LENS

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

A user of a portable device desires an optical device having a high resolution, a small size, and various photographing functions (eg, an optical image stabilizer (OIS) function, etc.). 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 the overall thickness is increased. Therefore, research on a liquid lens that performs autofocus and image stabilization functions by electrically controlling the curvature of the interface between two liquids is being conducted.

1. European Patent Application Publication EP1906213 (2008.04.02.) 2. Laid-open Patent Publication No. 10-2007-0120773 (2007.12.26.) 3. Japanese Patent Laid-Open No. 2009-047801 (2009.03.05)

The present invention can stabilize the movement of the interface within the liquid lens by controlling the voltage pulse for driving the liquid lens in a camera module including a liquid lens that can adjust the focal length using electrical energy and supplying it to a plurality of individual electrodes. Apparatus and methods may be provided.

In addition, in order to control the driving voltage in the form of a pulse applied to the liquid lens, the present invention can increase the operating speed of the liquid lens by adjusting the pulse period of the driving voltage according to the state of the liquid lens (eg, whether diopter is changed, etc.) Apparatus and methods may be provided.

In addition, the present invention can reduce the time required for the interface to be stabilized due to the free and flexible movement of the interface in the process of controlling the interface within the liquid lens by sequentially applying electrical energy to a plurality of individual electrodes of the liquid lens, It is possible to reduce an operation time according to a focus movement of a camera module or an optical device including a lens.

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 and a plurality of individual electrodes; a voltage generator generating a driving voltage for driving the liquid lens; and a first section in which the duty ratio of the driving voltage is changed when the Vrms value of the driving voltage applied between the common electrode and one of the plurality of individual electrodes is changed from the first Vrms value to the second Vrms value; A second section having a different duty ratio from the first section may be included, and at least one of the first section or the second section may have a duty ratio greater than a duty ratio in the section having the second Vrms value. there is.

Also, when the second Vrms value is greater than the first Vrms value, a duty ratio of a section having the second Vrms value may be smaller than a duty ratio of the first section.

Also, when the second Vrms value is greater than the first Vrms value, a duty ratio of a section having the second Vrms value may be greater than a duty ratio of a section having the first Vrms value.

Also, when the first Vrms value is greater than the second Vrms value, a duty ratio of a section having the second Vrms value may be greater than a duty ratio of the first section.

Also, when the second Vrms value is smaller than the first Vrms value, a duty ratio of a section having the second Vrms value may be smaller than a duty ratio of a section having the first Vrms value.

Also, the height and period of the pulse of the driving voltage may be constant.

In addition, having a third Vrms value in the first section, a fourth Vrms value in the second section, and (third Vrms value > second Vrms value > fourth Vrms value > first Vrms value) can be satisfied

In addition, having a third Vrms value in the first section, a fourth Vrms value in the second section, (first Vrms value > fourth Vrms value > second Vrms value > third Vrms value) can be satisfied

In addition, when the voltage applied to at least one of the common electrode and the plurality of individual electrodes is changed, the driving voltage period may include a period in which a preset first period is changed to a second period shorter than the first period. .

Also, the third Vrms value may be within 130% of the second Vrms value, and the fourth Vrms value may be within 85% of the second Vrms value.

Also, the width or period of the pulse of the driving voltage may be varied.

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 controls the duty ratio of the pulse pulses of the driving voltage of a liquid lens capable of adjusting the focal length to apply the excess voltage and the undervoltage to a plurality of individual electrodes when the driving voltage is changed. The movement of the interface can be obtained more quickly and stably.

In addition, according to the present invention, the movement of the interface according to the control of the liquid lens can be more stable and agile, so that the liquid lens can be mounted on a camera module or optical device with large and frequent movements.

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 module.
2 illustrates an example of a lens assembly included in a camera module.
3 illustrates a liquid lens whose focal length is adjusted in response to a driving voltage.
4 illustrates the structure of a liquid lens.
5 illustrates a lens correction method of a liquid lens.
6 illustrates the change of the interface within the liquid lens.
7 illustrates a first control method of a liquid lens through supply of an excess voltage.
8 illustrates a second method of controlling the liquid lens through the supply of excess voltage.
9 illustrates a liquid lens control circuit.
10A and 10B explain the driving method of the liquid lens.
11 describes a method of controlling the driving voltage of the liquid lens.

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

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

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

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

1 illustrates an example of a camera device. As shown, the camera module may include a lens assembly 22 and an image sensor. 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 based on the central axis of the liquid lens, and may include four individual terminals. The four individual terminals may be respectively disposed at the four corners of the liquid lens. When a voltage is applied through the individual terminals L1, L2, L3, and L4, the applied voltage is disposed in the lens region 310 by a driving voltage formed by interaction with a voltage applied to the common terminal C0, which will be described later. The interface between the electrically conductive liquid and the non-conductive liquid may be deformed.

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

4 illustrates the structure of a liquid lens.

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

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

In addition, the liquid lens 28 is located between the third plate 116 and the second plate 112, the third plate 116 and the second plate 112 including a transparent material, and has an opening having a preset inclined surface. It may include a first plate 114 including a region.

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

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

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

5 illustrates a lens correction method of a liquid lens.

First, referring to FIG. 5A , a user using a camera function of a portable terminal or portable device may move the portable terminal or portable device in an arbitrary direction (eg, arrow direction 32 ). The user's intention to move the portable terminal or the portable device in an arbitrary direction may be intentional, or may be unintentional, such as hand shake.

Referring to FIG. 5B , the liquid lens 28 mounted in the portable terminal or portable device can move substantially equally as much as the user intends the portable terminal or portable device to move (eg, arrows). direction (32)). This is because the liquid lens 28 is fixed to the portable terminal or portable device through various structures, mechanisms, means, and the like. Since the liquid lens 28 also moves according to the movement of the portable terminal or portable device, compensation for the movement is required when an image is received based on an optical signal received through the liquid lens 28 . For example, when the liquid lens 28 has an equivalent movement (eg, arrow direction 32) in response to movement of the portable terminal or portable device, in order to compensate the movement of the liquid lens 28, the liquid lens 28 ), the interface located in the lens region 310 needs to correct the received optical signal in the reverse direction (eg, the arrow direction 34 ).

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

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

Also, referring to (b), a case in which the voltage applied to the first individual electrodes L1 to the fourth individual electrodes L4 of the liquid lens 28 is lower than the case shown in (a) will be described. In this case, the inclination of the interface 30b is increased, so that the horizontal distance LH and the vertical distance LV when the shape of the interface 30b is longer than in the interface 30a shown in (a) can be longer when viewed from the top. there is.

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 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 a method of controlling a liquid lens by supplying an excess voltage.

Specifically, the driving voltage supplied to the liquid lens may be determined using a pulse width modulation (PWM) method. (a) is the case in which the excess voltage is not used, and (b) is the case in which the excess voltage is used. The period of the driving voltages in (a) and (b) is a constant case.

First, referring to (a), it is assumed that a change in the curvature or focus of the interface of the liquid lens 28 (refer to FIGS. 3 and 4) from the first state (S1) to the second state (S2) is required. Since the driving voltage of the liquid lens is a major variable that determines the shape of the liquid lens interface, the curvature or focal length of the liquid lens interface corresponding to the Vrms value of the driving voltage may be determined. Accordingly, the effective voltage Vrms may be changed by changing the driving voltage V to change from the first state S1 to the second state S2. The driving voltage V may be adjusted by adjusting the voltage applied to the common electrode or the individual electrodes of the liquid lens. The driving voltage V may change the amount of electric energy actually transferred through a change in a duty ratio (duty ratio) in a preset period. For example, the duty ratio of the driving voltage in the second state S2 may be greater than that in the first state S1 . The duty ratio D2 in the second state S2 may be greater than the duty ratio D1 in the first state S1 . An effective value (eg, root mean square, RMS) of the driving voltage V having such a waveform may be calculated as the effective voltage Vrms. A change in the shape of the liquid lens interface in the first state S1 and the second state S2 may occur in response to the change in the effective voltage Vrms, so that the focus of the liquid lens may be adjusted.

The interface in the liquid lens is formed between two liquids. Since the position, curvature, or movement of the interface is made by a change in the liquid, the refractive index of the liquid lens shows an unstable wave form as shown, but can be gradually stabilized. . If the time required for the interface to stabilize after inducing the movement of the interface within the liquid lens, that is, for the refractive index to change stably, is reduced, a camera module or optical device equipped with a liquid lens can perform faster operation. there is.

Referring to (b) of Figure 7, when a change from the first state (S1) to the second state (S2) is required in order to increase the driving speed of the liquid lens and reduce the unstable wave, the first transition period (O1) and the second The second transition period O2 may exist between two states (eg, the first state S1 and the second state S2), that is, at a changing time point. The first switching period O1 may be described as an overshooting voltage period, and the first switching period O1 may apply a voltage that is at most 30% higher than the target voltage. In addition, in order to prevent an overshooting voltage or undershooting voltage that does not belong to the normal range of the liquid lens from being applied to the liquid lens, in the second transition period O2, the voltage is set to 15% or less than the target voltage. By applying a low voltage, it is possible to reduce the application of the excess voltage of the initial driving. In the second state S2 after the first switching period O1 and the second switching period O2, a driving voltage corresponding to the range of the target voltage may be applied to the liquid lens. For example, the duty ratios D1, D3, D4, D2 of the first state S1, the first transition period O1, the second transition period O2, and the second state S2 are D3>D2> The size may be determined in the order of D4>D1.

7 (b) shows the first transition period O1 and the second transition in the process of changing from the first state S1 in which the effective voltage Vrms is low to the second state S2 in which the effective voltage Vrms is high. A case in which the section O2 exists has been described as an example. Meanwhile, a plurality of transition sections may be included in a process in which the effective voltage Vrms is converted from a high effective voltage Vrms to a low effective voltage Vrms state. For example, after applying a target voltage that is at most 30% or less lower than the target voltage in the first conversion section, a method of applying a voltage that is at most 15% higher than the target voltage in the second conversion section Through this, the movement of the liquid lens can be made faster. The case in which the first and second conversion sections exist has been described above as an example, but the present invention is not limited thereto, and additional conversion sections may further exist.

As described above, the apparatus and method for controlling a liquid lens may set a plurality of switching periods to speed up the driving of the liquid lens when the magnitude of the driving voltage applied to the liquid lens changes, particularly when the amount of change in the driving voltage is large. there is. For example, a voltage having a difference of 30% or more or less than the target voltage may be applied in one of the plurality of switching sections, and then a voltage having a difference of 15% or less or more than the target voltage may be applied in the other.

8 illustrates a method of controlling a liquid lens by supplying an excess voltage. Specifically, the driving voltage supplied to the liquid lens may be determined using a pulse width modulation (PWM) method. In addition, (a) of FIG. 8 illustrates a case where the excess voltage is not used, and (b) illustrates a case where the excess voltage is used. 8B is a case in which the period of the driving voltage is variable.

First, referring to (a), it is the same as (a) of FIG.

Referring to (b) of Figure 8, when a change from the first state (S1) to the second state (S2) is required in order to increase the driving speed of the liquid lens, the first transition period O1 and the second transition period ( O2) may exist between two states (eg, the first state S1 and the second state S2), that is, at a changing time point. The first switching period O1 may be described as an overshooting voltage period, and the first switching period O1 may apply a voltage 30% or more higher than the target voltage. In addition, in order to prevent an overshooting voltage or undershooting voltage that does not belong to the normal range of the liquid lens from being applied to the liquid lens, in the second transition period O2, the voltage is lowered by 15% or less than the target voltage. By applying the voltage, the application of the excess voltage of the initial driving may be reduced. In the second state S2 after the first switching period O1 and the second switching period O2, a driving voltage corresponding to the range of the target voltage may be applied to the liquid lens.

In addition, the pulse period P1 of the driving voltage applied to the liquid lens in the first transition period O1 and the second transition period O2 is applied to the liquid lens in the first state S1 and the second state S2. It may be shorter than the pulse period P2 of the driving voltage. When a change in the driving voltage is required, the pulse period P1 of the driving voltage may be shortened, and when there is no change in the driving voltage, the pulse period P2 of the driving voltage may be lengthened.

8 (b) is a first transition period O1 and second in the process of changing from the first state (S1) in which the effective voltage (Vrms) is low to the second state (S2) in which the effective voltage (Vrms) is high A case in which the conversion section O2 exists has been described as an example. Meanwhile, a plurality of transition sections may be included in a process in which the effective voltage Vrms is converted from a high effective voltage Vrms to a low effective voltage Vrms state. For example, after applying a target voltage that is 30% or less lower than the target voltage in the first switching section, applying a voltage 15% or more higher than the target voltage in the second switching section Lens movement can be made faster.

As described above, the apparatus and method for controlling a liquid lens may set a plurality of switching periods to speed up the driving of the liquid lens when the magnitude of the driving voltage applied to the liquid lens changes, particularly when the change in the driving voltage is large. there is. For example, a voltage having a difference of 30% or more or less than the target voltage may be applied in one of the plurality of switching sections, and then a voltage having a difference of 15% or less or more than the target voltage may be applied in the other.

In addition, in FIG. 8(b) , an embodiment having different pulse periods (operating frequencies) corresponding to a period in which there is no change in the driving voltage and a period in which there is a change has been described, but according to the embodiment, the pulse period (operation frequency) can be further subdivided and diversified. Different pulse periods may be used depending on when the driving voltage is increased, when the driving voltage is decreased, when the driving voltage is maintained at a high voltage, or when the driving voltage is maintained at a low voltage.

9 illustrates a liquid lens control circuit.

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

The first to fourth voltages and voltages V _L1 , V _L2 , V _L3 , V _L4 , and V _C0 may be applied from the liquid lens control circuit 50 . The liquid lens control circuit 50 controls the amount of diopter change of the interface within the liquid lens, or a plurality of individual electrodes (L1, L2, L3, L4) and a common electrode (C0, see Fig. 3) in the liquid lens to change the diopter. It is possible to control the voltage applied to the In addition, the liquid lens control circuit 50 may set and control a switching period in a process in which a driving voltage is changed by applying a voltage to the plurality of individual electrodes L1, L2, L3, and L4 and the common electrode C0. .

The liquid lens control circuit 50 includes a lens driving determining unit 54 that determines the diopter change amount of the liquid lens 28 interface 30, a plurality of individual electrode sectors L1 of the liquid lens 28 in response to the diopter change amount, A voltage generator 56 for controlling a voltage to be applied to each of L2, L3, L4 and the common electrode sector C0, and a plurality of individual electrode sectors L1, L2, L3, L4 and the common electrode sector corresponding to the diopter variation amount The electrode sector C0 may include a switching voltage controller 52 that controls at least one switching section when the driving voltage is changed. The liquid lens control circuit 50 may receive information about the movement of the liquid lens 28 from various sensors (eg, a gyro sensor, etc.) included in the device on which the liquid lens is mounted. In addition, when a user's input through a user interface or the like generates a diopter change amount of the liquid lens 28 , information corresponding to the input may be transmitted to the liquid lens control circuit 50 .

When the compensation value to be compensated is determined through the movement of the interface 30 in the liquid lens 28 , the corresponding voltages V _L1 , V _L2 , V _L3 , V _L4 , V _C0 are applied in the liquid lens 28 . It may be applied to each of the plurality of individual electrodes L1 , L2 , L3 , and L4 and the common electrode C0 . In this process, the switching voltage controller 52 applies the target voltage to the plurality of individual electrodes L1, L2, L3, L4 and the common electrode C0 during the switching period according to the target voltage of the liquid lens driving voltage. Alternatively, the following voltage may be applied.

For example, when the voltages V _L1 , V _L2 , V _L3 , and V _L4 applied to the first individual electrode L1 to the fourth individual electrode L4 change from 30V to 50V, the target voltage is 30V higher than the target voltage of 50V. The switching section can be controlled by applying a voltage that is higher than % and then applying a voltage that is 15% or less lower than the target voltage of 50V. The first driving voltage V _L1 supplied to the first individual electrodes L1 through the switching voltage control unit 52 for controlling the switching section is applied with a voltage higher than a preset range or lower than a preset range than the target voltage. can do.

According to an exemplary embodiment, the switching period for each individual electrode may be sequentially controlled or controlled together while the voltage supplied to the first individual electrode L1 to the fourth individual electrode L4 is changed. The switching voltage controller 52 sets a plurality of switching sections to speed up the driving of the liquid lens when the magnitude of the driving voltage applied to the liquid lens 28 changes, particularly when the amount of change in the driving voltage is large, and during the switching section The magnitude of the applied voltage can be controlled. For example, according to the direction in which the driving voltage is changed (rising or falling), a voltage having a difference of at most 30% or more or less than the target voltage is applied in one of the plurality of switching sections, and then the target voltage is higher than the target voltage in the other. A voltage with a difference of up to 15% or more can be applied.

10A and 10B explain the driving method of the liquid lens.

Referring to FIG. 10A , the driving voltage supplied to the liquid lens may be applied through the common electrode C0 and the individual electrodes L1 to L4 (refer to FIG. 9 ). The driving voltage V affecting the change of the interface within the liquid lens may be substantially equal to the absolute value of the difference between the voltages applied to the common electrode C0 and the individual electrode L1.

As described in FIG. 8 , the driving voltage applied through the common electrode C0 and the individual electrodes L1 to L4 uses a pulse width modulation (PWM) method. In the pulse width modulation (PWM) method, the duty ratio (duty ratio) of the driving voltage in the form of a pulse may be changed in response to a driving voltage to be applied to the liquid lens and a target driving voltage (Vrms).

In the general pulse width modulation (PWM) method, the duty ratio of the pulse is adjusted, but in FIG. 10, not only the duty ratio of the pulse but also the period (operating frequency) of the pulse may be changed. The pulsed driving voltages applied to the common electrode C0 and the individual electrodes L1 of the liquid lens may have different pulse periods P1 and P2 as well as an adjustable pulse width. The period P2 in the period in which the driving voltage of a constant level is applied may be longer than the period P1 in the period in which the level of the driving voltage is changed.

In order to prevent image stabilization (OIS), the operating speed of the liquid lens may be increased by quickly changing the driving voltage that adjusts the movement of the interface within the liquid lens. To this end, by applying a higher voltage than the target driving voltage and then applying a lower voltage, the driving voltage may be changed more rapidly. In addition, in order to speed up the driving speed of the liquid lens, the pulse period of the driving voltage applied to the common electrode C0 and the individual electrode L1 is changed to make the driving voltage change faster. can be changed That is, the pulse period (P1) in the same section as the first switching section (O1) and the second switching section (O2) described in (b) of FIG. 8 may be shorter than the pulse period (P2) in other sections Similarly, the driving voltage described with reference to FIG. 10 may be similarly applied.

Referring to FIG. 10B , it is described that the period or operating frequency of the common electrode C0 and the individual electrode L1 is variously changed (P0, P1, P2, etc.) in order to realize the target driving voltage Vrms. . The pulse of the driving voltage V determined by the voltage difference between the common electrode C0 and the individual electrode L1 changes the period or operating frequency of the driving voltage applied to the common electrode C0 and the individual electrode L1. can be changed to

11 describes a method of controlling the driving voltage of the liquid lens. Specifically, in the embodiment described in (a) and (b) of FIG. 11 , a period (operation frequency) can be adjusted unlike a general pulse width modulation (PWM) method.

Referring to FIG. 11A , as described with reference to FIGS. 7B and 9 , it is a method of changing the duty ratio and period of the driving voltage applied to the common electrode C0 and the individual electrode L1 . In particular, a case in which the duty ratio of 50% is changed to the duty ratio of 75% while the cycle of the driving voltage applied to the common electrode C0 and the individual electrode L1 is changed from the long cycle P11 to the short cycle P12 Explain. Here, the driving voltage V affecting the interface of the liquid lens is the difference (absolute value) of voltages applied to the common electrode C0 and the individual electrode L1. By controlling the duty ratio of the driving voltages applied to the common electrode C0 and the individual electrodes L1, the magnitude of the driving voltage V affecting the interface of the liquid lens can be adjusted. In addition, by changing the period (operation frequency) of the driving voltage applied to the common electrode C0 and the individual electrode L1 , it is possible to realize finer and more precise control (reduction of noise and damping, etc.).

Meanwhile, although an example has been described in which the duty ratio of the driving voltages applied to the common electrode C0 and the individual electrode L1 is identically changed (from 50% to 75%), the common electrode C0 and the individual electrode L1 have been described. ) may be adjusted to be different duty ratios of the driving voltages applied to each other. For example, the duty ratio of the common electrode C0 is 50%, but the duty ratio of the individual electrode L1 may be 75%. In addition, duty ratios of driving voltages applied to each of the individual electrodes L1 to L4 (refer to FIG. 8 ) may be the same or different from each other. Through this method, the size of the driving voltage V applied through each of the individual electrodes L1 to L4 and the common electrode C0 of the liquid lens can be adjusted to be different or the same, and through this, the focus of the liquid lens can be controlled. can do.

Also, referring to FIG. 11B , in a state where the duty ratios of the driving voltages applied to the common electrode C0 and the individual electrode L1 are the same, the driving voltage cycle of the common electrode C0 is a long period P13. is maintained and the driving voltage V affecting the interface of the liquid lens is adjusted by changing the driving voltage cycle of the individual electrode L1 from the long cycle P13 to the short cycle P14. Even if the duty ratio (eg, 50%) of the driving voltages applied to the common electrode C0 and the individual electrodes L1 is the same, the cycles of the driving voltages applied to the common electrode C0 and the individual electrodes L1 are different from each other. can do. That is, the period of the driving voltage applied to the common electrode C0 and the individual electrode L1 may be adjusted to be the same or different. In addition, the period of the driving voltage applied to each of the individual electrodes L1 to L4 (refer to FIG. 8 ) may be different or may be the same. Through this method, the size of the driving voltage V applied through each of the individual electrodes L1 to L4 and the common electrode C0 of the liquid lens can be adjusted to be different or the same, and through this, the focus of the liquid lens can be controlled. can do.

The liquid lens described above may be included in a camera module or a camera device. 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 an optical device 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 by a computer and stored in a computer-readable recording medium. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape. , floppy disks, optical data storage devices, and the like.

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

It is apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit and essential characteristics of the present invention. Accordingly, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (15)

A liquid lens comprising a common electrode and a plurality of individual electrodes; And
A control unit for controlling a driving voltage for driving the liquid lens,
When the effective voltage (Vrms) value of the driving voltage applied between any one of the plurality of individual electrodes and the common electrode is changed from the first effective voltage value to the second effective voltage value,
The driving voltage pulse includes a first switching section having a first duty ratio and a second switching section having a second duty ratio different from the first switching section,
Any one of the first duty ratio and the second duty ratio has a duty ratio greater than a duty ratio in a section having the second effective voltage value;
Any one of the period of the driving voltage pulse of the first switching period and the period of the driving voltage pulse of the second switching period is shorter than the period of the driving voltage pulse of the period having the second effective voltage value Liquid lens control circuit. delete According to claim 1,
A period of the driving voltage pulse in the first switching period and a period of the driving voltage pulse in the second switching period are shorter than a period of the driving voltage pulse in the period having the second effective voltage value. Circuit. According to claim 1,
The effective voltage value of the first switching section is greater than the second effective voltage value, and the effective voltage value of the second switching section is smaller than the second effective voltage value. 5. The method of claim 4,
The effective voltage value of the first switching period is 130% or more of the second effective voltage value, and the effective voltage value of the second switching period is 85% or less of the second effective voltage value. According to claim 1,
A liquid lens control circuit in which the width and period of the driving voltage pulse in the first switching period are constant. According to claim 1,
The first effective voltage value is smaller than the second effective voltage value. According to claim 1,
The first effective voltage value is greater than the second effective voltage value, the effective voltage value of the first switching section is smaller than the second effective voltage value, and the effective voltage value of the second switching section is the second effective voltage value Larger liquid lens control circuit. a liquid lens including a common electrode and a plurality of individual electrodes; and
A control unit for controlling a driving voltage for driving the liquid lens,
applied between the common electrode and one of the plurality of individual electrodes.
When the effective voltage (Vrms) value of the driving voltage is changed from the first effective voltage value to the second effective voltage value,
The driving voltage pulse includes a first period having a first period and a first pulse width and a second period having a second period and a second pulse width,
The first period is shorter than the period of the pulse of the driving voltage in the section having the second effective voltage value,
The first pulse width is smaller than a pulse width of a driving voltage in a section having the second effective voltage value. 10. The method of claim 9,
The first pulse width is greater than the size of the second pulse width,
The effective voltage value of the first section is 130% or more of the second effective voltage value, and the effective voltage value of the second section is 85% or less of the second effective voltage value. a liquid lens including a common electrode and a plurality of individual electrodes; and
A control unit for controlling a driving voltage for driving the liquid lens,
When the control unit changes an effective voltage (Vrms) value of a driving voltage applied between any one of the plurality of individual electrodes and the common electrode from a first effective voltage value to a second effective voltage value, the driving voltage this
an initial voltage section having the first effective voltage value;
a transition period in which the first effective voltage value is converted to the second effective voltage value; and
Control to have a target voltage section having the second effective voltage value,
The transition period is
a first switching section having an effective voltage difference greater than a difference between the first effective voltage value and the second effective voltage value compared to the first effective voltage value; and
a second switching section having an effective voltage difference smaller than a difference between the first effective voltage value and the second effective voltage value compared to the second effective voltage value,
The driving voltage is applied in the form of a pulse wave,
Each section has a duty ratio corresponding to a corresponding effective voltage value, a liquid lens control circuit. 12. The method of claim 11,
When the first effective voltage value is greater than the second effective voltage value,
The effective voltage value of the first switching section is smaller than the second effective voltage value,
The effective voltage value of the second switching period is greater than the second effective voltage value, the liquid lens control circuit. 13. The method of claim 12,
The pulse wave period of the first switching section is longer than the pulse wave period of the target voltage section,
The pulse wave period of the second switching period is shorter than the pulse wave period of the target voltage period. 12. The method of claim 11,
When the second effective voltage value is greater than the first effective voltage value,
The effective voltage value of the first switching section is greater than the second effective voltage value,
The effective voltage value of the second switching period is smaller than the second effective voltage value, the liquid lens control circuit. 15. The method of claim 14,
The pulse wave period of the first switching section is shorter than the pulse wave period of the target voltage section,
The pulse wave period of the second switching period is longer than the pulse wave period of the target voltage period.

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