Actuator for camera module

Abstract

The actuator of the camera module includes a magnet disposed on the lens barrel, a driving coil disposed opposite to the magnet, and a driving device, wherein the driving device includes a comparator, a controller IC, and a driving circuit, wherein the comparator calculates an error value by comparing a target position of the lens barrel with a current position of the lens barrel, the controller IC generates a control signal by applying a control gain to the error value, and the driving circuit generates a driving signal in response to the control signal. The controller IC determines the control gain based on a friction coefficient between a guide groove guiding the movement of the lens barrel and a ball bearing contacting the guide groove. The controller IC provides a detection signal with a gradually increasing level to the driving coil, and determines the friction coefficient based on the level of the detection signal at a time point when the lens barrel moves.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2020-0023119 filed on February 25, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] The following description relates to an actuator of a camera module. Background Art

[0004] Generally, portable communication terminals such as mobile phones, PDAs, portable PCs, etc. have recently been popularized to perform not only the transmission of text or voice data but also the transmission of video data. In response to this trend, in order to enable the transmission of video data or video chatting, a camera module is installed in the portable communication terminal.

[0005] Typically, a camera module includes a lens barrel having a lens therein and a housing in which the lens barrel is housed, and also includes an image sensor configured to convert an image of an object into an electrical signal. The camera module may be a single-focus camera module that images an object with a fixed focus. However, recently, a camera module including an actuator capable of automatic focus (AF) adjustment has been implemented in a portable communication terminal. In addition, the camera module uses an actuator for optical image stabilization (OIS) to reduce resolution degradation caused by shaking.

[0006] In order to accurately control the auto focus function and shake correction function applied to the camera module, it is necessary to move the lens barrel to a target position. However, the lens barrel may not converge to the target position and an oscillation problem may occur. Summary of the invention

[0007] The purpose of providing this summary is to introduce a selection of inventive concepts in a concise form, and these inventive concepts will be further described in the following detailed description. This summary is not intended to identify the key features or essential features of the subject matter claimed, nor is it intended to help determine the scope of the subject matter claimed.

[0008] In a general aspect, an actuator of a camera module includes: a magnet disposed on a lens barrel; a drive coil disposed opposite to the magnet; and a drive device, the drive device including a comparator, a controller IC, and a drive circuit, wherein the comparator is configured to calculate an error value by comparing a target position of the lens barrel with a current position of the lens barrel, the controller IC is configured to generate a control signal by applying a control gain to the error value, and the drive circuit is configured to generate a drive signal in response to the control signal. The controller IC is also configured to determine the control gain based on a friction coefficient between a guide groove that guides movement of the lens barrel and a ball bearing that contacts the guide groove. The controller IC is also configured to provide a detection signal with a gradually increasing level to the drive coil, and determine the friction coefficient based on the level of the detection signal at a point in time when the lens barrel moves.

[0009] The control gain can be provided by a PID controller.

[0010] The controller IC may also be configured to increase the control gain in response to the friction coefficient being greater than a reference friction coefficient, and to decrease the control gain in response to the friction coefficient being less than the reference friction coefficient.

[0011] The controller IC may also be configured to receive a gyroscope signal including angle information of the guide slot.

[0012] The controller IC may also be configured to correct the friction coefficient based on the angle information of the guide groove.

[0013] The actuator may further include a position detector including a Hall element configured to detect a position of the lens barrel.

[0014] The guide grooves and ball bearings may be configured to have a lubricant applied thereto.

[0015] The controller IC may also be configured to model the level of the detection signal at a point in time when the lens barrel moves as a static friction force.

[0016] The drive circuit may also be configured to provide a drive signal to the drive coil to perform any of: moving the lens barrel in the optical axis direction for an autofocus function, and moving the lens barrel in a direction perpendicular to the optical axis direction for an image stabilization function.

[0017] In another general aspect, the actuator of the camera module includes: a magnet, which is arranged on the lens barrel; a driving coil, which is arranged opposite to the magnet; and a driving device, which includes a comparator, a controller IC and a driving circuit, wherein the comparator is configured to calculate an error value by comparing the target position of the lens barrel with the current position of the lens barrel, the controller IC is configured to generate a control signal by applying a control gain to the error value, and the driving circuit is configured to generate a driving signal in response to the control signal to move the lens barrel to the target position. The controller IC is also configured to determine the control gain based on the friction coefficient between the guide groove that guides the movement of the lens barrel and the ball bearing that contacts the guide groove. The controller IC is also configured to provide a detection signal to the driving coil, and the level of the detection signal at the time point when the lens barrel moves is modeled as a static friction force to determine the friction coefficient.

[0018] The control gain can be provided by a PID controller.

[0019] The controller IC may also be configured to increase the control gain in response to the friction coefficient being greater than a reference friction coefficient, and to decrease the control gain in response to the friction coefficient being less than the reference friction coefficient.

[0020] The controller IC may also be configured to receive a gyroscope signal including angle information of the guide slot.

[0021] The controller IC may also be configured to correct the friction coefficient based on the angle information of the guide groove.

[0022] The actuator may further include a position detector including a Hall element configured to detect a position of the lens barrel.

[0023] The guide grooves and ball bearings may be configured to have a lubricant applied thereto.

[0024] The detection signal may have a gradually increasing level.

[0025] The drive circuit may also be configured to provide a drive signal to the drive coil to perform any of: moving the lens barrel in the optical axis direction for an autofocus function, and moving the lens barrel in a direction perpendicular to the optical axis direction for an image stabilization function.

[0026] Other features and aspects will become apparent from the following detailed description, the accompanying drawings, and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is an exploded perspective view of a camera module according to an example.

[0028] Figure 2 is a block diagram of main parts of an actuator used in a camera module according to an example.

[0029] Figure 3 is a block diagram of a drive device used in an actuator according to an example.

[0030] Figure 4 is a block diagram of a controller IC according to an example.

[0031] Throughout the drawings and detailed description, the same reference numerals refer to the same elements. For purposes of clarity, illustration, and convenience, the drawings may not be drawn to scale, and the relative sizes, proportions, and depictions of elements in the drawings may be exaggerated. DETAILED DESCRIPTION

[0032] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the method, device and / or system described in this application. However, after understanding the disclosure of this application, various changes, modifications and equivalences of the method, device and / or system described in this application will be obvious. For example, the order of operations described in this application is only an example, and except for the operations that must occur in a specific order, it is not limited to the order set forth in this application, but can make obvious changes after understanding the disclosure of this application. In addition, for greater clarity and simplicity, the description of features well known in the art may be omitted.

[0033] The features described in this application can be implemented in different forms and should not be understood as being limited to the examples described in this application. More specifically, the examples described in this application are provided only to illustrate some of the many possible ways to implement the methods, devices and / or systems described in this application, which will be apparent after understanding the disclosure of this application.

[0034] It should be noted that in this application, the use of the word "may" with respect to examples or embodiments, for example, regarding what an example or embodiment may include or implement, means that there is at least one example or embodiment that includes or implements such features, and all examples and embodiments are not limited thereto.

[0035] Throughout the specification, when an element such as a layer, a region, or a substrate is described as being “on,” “connected to,” or “coupled to” another element, the element may be directly “on,” “connected to,” or “coupled to” the other element, or one or more other elements may be present between the element and the other element. Conversely, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there may be no other elements between the element and the other element.

[0036] As used in this application, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0037] Although the terms "first", "second" and "third" may be used in this application to describe various members, components, regions, layers or parts, these members, components, regions, layers or parts are not limited by these terms. More specifically, these terms are only used to distinguish one member, component, region, layer or part from another member, component, region, layer or part. Therefore, without departing from the teachings of the examples described in this application, the first member, first component, first region, first layer or first part mentioned in these examples may also be referred to as the second member, second component, second region, second layer or second part.

[0038] Spatially relative terms such as "above", "higher", "below", and "lower" may be used in this application for descriptive convenience to describe the relationship of one element relative to another element as shown in the accompanying drawings. In addition to covering the orientations depicted in the accompanying drawings, these spatially relative terms are intended to also cover different orientations of the device in use or operation. For example, if the device in the accompanying drawings is flipped, an element described as being "above" or "higher" relative to another element will be "below" or "lower" relative to the other element. Therefore, depending on the spatial orientation of the device, the term "above" covers both "above" and "below" orientations. The device may also be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and the spatially relative terms used in this application should be interpreted accordingly.

[0039] The terms used in this application are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the articles "a", "an" and "the" are intended to also include plural forms. The words "include", "comprise" and "have" indicate the presence of the features, numbers, operations, components, elements and / or their combinations, but do not exclude the presence or addition of one or more other features, numbers, operations, components, elements and / or their combinations.

[0040] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described in the present application are not limited to the specific shapes shown in the drawings, but include variations in shapes that occur during manufacturing.

[0041] The features of the examples described in this application can be combined in various ways that will be apparent after understanding the disclosure of this application. In addition, although the examples described in this application have multiple configurations, other configurations that will be apparent after understanding the disclosure of this application are also possible.

[0042] Figure 1 is an exploded perspective view of a camera module 100 according to an example.

[0043] refer to Figure 1 , the camera module 100 may include, for example, a housing unit 110 , an actuator 120 , and a lens module 130 , and may further include a ball bearing unit 140 .

[0044] The camera module 100 may include either or both of an auto focus function and an optical image stabilization function. For example, the camera module 100 may drive the lens module 130 in the optical axis direction (e.g., Z axis direction) and in directions perpendicular to the optical axis direction (e.g., X axis direction and Y axis direction) inside the housing unit 110 to perform the auto focus function and the optical image stabilization function.

[0045] The housing unit 110 may include a housing 111 and a shield case 112. The housing 111 may be formed of a material that is easily molded. For example, the housing 111 may be formed of a plastic material. The housing 111 may be equipped with at least one actuator 120.

[0046] For example, the actuator 120 may include a first actuator 121 and a second actuator 122. A portion of the first actuator 121 may be mounted on a first side of the housing 111, and a portion of the second actuator 122 may be mounted on second and third sides of the housing 111.

[0047] The housing 111 is configured to accommodate the lens module 130 in the housing 111. For example, a space in which the lens module 130 may be fully or partially accommodated is formed inside the housing 111.

[0048] The housing 111 may have, for example, a six-sided opening shape. For example, a hole for an image sensor may be formed in the lower surface of the housing 111, and a quadrilateral hole in which the lens module 130 is formed may be formed in the upper surface of the housing 111.

[0049] The first side of the shell 111 can be opened in such a manner that the first drive coil 121a of the first actuator 121 can be inserted into the first side of the shell 111, and the second and third sides of the shell 111 can be opened in such a manner that the second drive coil 122a of the second actuator 122 can be inserted into the second and third sides of the shell 111.

[0050] The shield shell 112 is configured to cover a portion of the housing 111. For example, the shield shell 112 may be configured to cover the upper surface and four sides of the housing 111. Alternatively, the shield shell 112 may be configured to cover only the four sides of the housing 111, or the shield shell 112 may be configured to partially cover the upper surface and four sides of the housing 111.

[0051] The shielding case 112 may shield electromagnetic waves generated during driving of the camera module 100. When the camera module 100 is driven, electromagnetic waves are generated, and in the case where the electromagnetic waves are emitted outward, the electromagnetic waves may affect other electronic components, causing communication failure or malfunction. In order to prevent such failure or malfunction, the shielding case 112 is formed of a metal material and is grounded to a ground pad of a substrate mounted on a lower portion of the housing 111 to shield the electromagnetic waves.

[0052] For example, the first actuator 121 may drive the lens module 130 in the Z-axis direction, and the second actuator 122 may drive the lens module 130 in the X-axis direction and the Y-axis direction.

[0053] The first actuator 121 may be mounted on the housing 111 and the first frame 131 of the lens module 130. For example, a portion of the first actuator 121 may be mounted on a first side of the housing 111, and the rest of the first actuator 121 may be mounted on a first side of the first frame 131.

[0054] The first actuator 121 may move the lens module 130 in the optical axis direction (Z-axis direction). For example, the first actuator 121 may include a first driving coil 121a, a first magnet 121b, a first substrate 121c, and a first position detecting element 121d.

[0055] The first driving coil 121a and the first position detecting element 121d are formed on the first substrate 121c. The first substrate 121c is mounted on a first side of the housing 111, and the first magnet 121b is mounted on a first side 131c of the first frame 131 facing the first substrate 121c.

[0056] A first driver that provides a driving signal to the first driving coil 121a may be disposed on the first substrate 121c. The first driver may provide a driving force to the first magnet 121b by applying a driving signal to the first driving coil 121a. For example, when a driving signal from the first driver is provided to the first driving coil 121a, a magnetic flux is generated in the first driving coil 121a, and the magnetic flux generated in the first driving coil 121a interacts with the magnetic field of the first magnet 121b to generate a driving force that enables the first frame 131 and the lens barrel 134 to move relative to the housing 111.

[0057] The first driver may include an H-bridge circuit capable of bidirectional driving in the first driver to apply a driving signal to the first driving coil 121 a .

[0058] The lens barrel 134 may move in the same direction as the first frame 131 by movement of the first frame 131. The first actuator 121 may detect the magnetic field strength of the first magnet 121b using the first position detecting element 121d to detect the positions of the first frame 131 and the lens barrel 134. As an example, the first position detecting element 121d may include a Hall element.

[0059] The second actuator 122 may be mounted on the housing 111 and the third frame 133 of the lens module 130. For example, a portion of the second actuator 122 may be mounted on the second and third sides of the housing 111, and the rest of the second actuator 122 may be mounted on the second and third sides of the third frame 133.

[0060] The second actuator 122 includes elements configured to move the lens module 130 in a direction perpendicular to the optical axis. For example, the second actuator 122 may include a plurality of second driving coils 122a, a plurality of second magnets 122b, a second substrate 122c, and a second position detecting element 122d.

[0061] A plurality of second drive coils 122a and second position detection elements 122d are formed on the second substrate 122c. The second substrate 122c may have a substantially quadrilateral form with one side thereof being open, and may be installed, for example, in a form surrounding the second side to the fourth side of the housing 111. A plurality of second magnets 122b are respectively installed on the second side and the third side of the third frame 133 to face the second substrate 122c.

[0062] A second driver configured to provide a driving signal to the second driving coil 122a may be disposed on the second substrate 122c. The second driver may provide a driving force to the second magnet 122b by applying a driving signal to the second driving coil 122a. When a driving signal from the second driver is provided to the second driving coil 122a, a magnetic flux is generated in the second driving coil 122a, and the magnetic flux generated by the second driving coil 122a interacts with the magnetic field of the second magnet 122b. The second driver changes the magnitude and direction of the magnetic force generated between the plurality of second driving coils 122a and the plurality of second magnets 122b so as to enable the second frame 132 or the third frame 133 to move relative to the first frame 131.

[0063] The second driver may include an H-bridge circuit capable of bidirectional driving in the second driver to apply a driving signal to the second driving coil 122 a .

[0064] The lens barrel 134 can move in the same direction as the second frame 132 or the third frame 133 by the movement of the second frame 132 or the third frame 133. The second actuator 122 senses the strength of the magnetic field of the second magnet 122b using the second position detection element 122d, and thus can detect the positions of the lens barrel 134, the second frame 132, and the third frame 133.

[0065] As an example, the second position detecting element 122d may include a Hall element. The second position detecting element 122d may include at least two Hall elements to detect the position of the lens barrel 134 in two directions perpendicular to the optical axis.

[0066] The lens module 130 is accommodated in the housing unit 110. For example, the lens module 130 is accommodated to be movable in at least three axes in the accommodation space formed by the housing 111 and the shielding shell 112. The lens module 130 includes a plurality of frames. As an example, the lens module 130 includes a first frame 131, a second frame 132, and a third frame 133.

[0067] The first frame 131 is configured to be movable relative to the housing 111. For example, the first frame 131 can be moved in the optical axis direction (Z-axis direction) of the housing 111 by the first actuator 121. A plurality of guide grooves 131a and 131b are formed in the first frame 131. For example, the first guide groove 131a extends in the optical axis direction (Z-axis direction) and is formed in the first side of the first frame 131, and the second guide groove 131b extends in the first direction (Y-axis direction) perpendicular to the optical axis and is respectively formed in the four corners of the inner bottom surface of the first frame 131. The first frame 131 is configured to be movable relative to the housing 111 in the optical axis direction (Z-axis direction). For example, the first frame 131 can be moved in the optical axis direction (Z-axis direction) along the first guide groove 131a.

[0068] The first frame 131 is configured such that at least three sides of the first frame 131 are open. For example, the second side and the third side of the first frame 131 are open such that the second driving coil 122a and the second magnet 122b are opposite to each other.

[0069] The second frame 132 may be mounted on the first frame 131. For example, the second frame 132 may be mounted in the inner space of the first frame 131. The second frame 132 is configured to move in a first direction (Y-axis direction) perpendicular to the optical axis relative to the first frame 131. For example, the second frame 132 may move in the first direction (Y-axis direction) perpendicular to the optical axis along the second guide groove 131b of the first frame 131.

[0070] A plurality of guide grooves 132a are formed in the second frame 132. For example, four third guide grooves 132a extending in a second direction (X-axis direction) perpendicular to the optical axis are formed at the corners of the second frame 132. The third frame 133 is mounted on the second frame 132. For example, the third frame 133 may be mounted on the upper surface of the second frame 132. The third frame 133 is configured to move relative to the second frame 132 in a second direction (X-axis direction) perpendicular to the optical axis. For example, the third frame 133 may move along the third guide grooves 132a of the second frame 132 in a second direction (X-axis direction) perpendicular to the optical axis. A plurality of second magnets 122b are mounted on the third frame 133. For example, at least two second magnets 122b may be mounted on the second side and the third side of the third frame 133, respectively.

[0071] The lens barrel 134 can move in the optical axis direction (Z axis direction), the first direction perpendicular to the optical axis (Y axis direction) and the second direction perpendicular to the optical axis (X axis direction) through the above-mentioned first guide groove 131a, second guide groove 131b and third guide groove 132a.

[0072] The lens module 130 includes a lens barrel 134. For example, the lens barrel 134 may include one or more lenses. The lens barrel 134 may have a hollow cylindrical shape so that one or more lenses for imaging an object may be accommodated in the lens barrel 134, and the lenses may be arranged in the lens barrel 134 along an optical axis. The one or more lenses may be stacked in a number designed according to the design of the lens barrel 134, and may have optical properties such as the same or different refractive indices.

[0073] The lens barrel 134 is mounted on the third frame 133. For example, the lens barrel 134 is coupled to the third frame 133 and can move integrally with the third frame 133. The lens barrel 134 is configured to move in the optical axis direction (Z-axis direction) and in the first and second directions (Y-axis direction and X-axis direction) perpendicular to the optical axis. For example, the lens barrel 134 moves in the optical axis direction (Z-axis direction) by the first actuator 121, and moves in the first and second directions (Y-axis direction and X-axis direction) perpendicular to the optical axis by the second actuator 122.

[0074] The ball bearing unit 140 may guide the movement of the lens module 130. For example, the ball bearing unit 140 is configured to allow the lens module 130 to move in the optical axis direction and in the first direction and the second direction perpendicular to the optical axis. The ball bearing unit 140 may include a first ball bearing 141, a second ball bearing 142, and a third ball bearing 143. As an example, the first ball bearing 141 may be disposed in the first guide groove 131a of the first frame 131 so that the first frame 131 can move in the optical axis direction (Z-axis direction). As another example, the second ball bearing 142 is disposed in the second guide groove 131b of the first frame 131 so that the second frame 132 can move in the first direction (Y-axis direction) perpendicular to the optical axis. As another example, the third ball bearing 143 is disposed in the third guide groove 132a of the second frame 132 so that the third frame 133 can move in the second direction (X-axis direction) perpendicular to the optical axis. Each of the first ball support 141 and the second ball support 142 may include at least three spherical members, and the at least three spherical members of the ball support may be disposed in the first guide groove 131 a or the second guide groove 131 b .

[0075] The lubricant may be filled and applied to the ball bearing unit 140 and the guide groove contacting the ball bearing unit 140. Friction and noise may be reduced by the lubricant. The lubricant may include lubricating oil having excellent viscosity and lubrication properties.

[0076] Figure 2 is a block diagram of main parts of an actuator 200 used in a camera module according to an example.

[0077] The actuator 200 may include, for example, a driving device 210, a driving coil 220, a detectable member 230, and a position detector 240. The actuator 200 may correspond to Figure 1 Any one of the first actuator 121 and the second actuator 122.

[0078] The actuator 200 corresponds to Figure 1 In the example of the first actuator 121, the actuator 200 may enable the lens barrel to move in the optical axis direction (Z-axis direction) to perform an auto focus (AF) function of the camera module 100. Therefore, when the actuator 200 performs the automatic focusing function, the driving device 210 may apply a driving signal to the driving coil 220 to provide a driving force to the magnet in the optical axis direction (Z-axis direction).

[0079] In addition, the actuator 200 corresponds to Figure 1 In the example of the second actuator 122, the actuator 200 can enable the lens barrel to move in a direction perpendicular to the optical axis (Y-axis direction or X-axis direction) to perform an optical image stabilization (OIS) function of the camera module 100. Figure 2When the actuator 200 performs the OIS function, the driving device 210 may apply a driving signal to the driving coil 220 to provide a driving force to the magnet in a direction perpendicular to the optical axis (Y-axis direction or X-axis direction).

[0080] The driving device 210 generates a driving signal Sdr in response to an externally inputted input signal Sin and a feedback signal Sf generated from the position detector 240 , and may provide the generated driving signal Sdr to the driving coil 220 . Figure 1 The target position of the lens barrel 134 may be determined by the input signal Sin. For example, the position detector 240 may include a Hall element.

[0081] For example, in the case where the actuator 200 corresponds to the first actuator 121, the input signal Sin may indicate the target position of the lens barrel 134 in the optical axis direction (Z-axis direction). As another example, in the example where the actuator 200 corresponds to the second actuator 122, the input signal Sin may indicate the target position of the lens barrel 134 in the direction perpendicular to the optical axis (Y-axis direction or X-axis direction).

[0082] When a driving signal Sdr provided by the driving device 210 is applied to the driving coil 220 , the lens barrel 134 may move in one direction by electromagnetic interaction between the driving coil 220 and the magnet.

[0083] The detectable member 230 may be provided on one side of the lens barrel 134 to move in the same direction as the movement direction of the lens barrel 134. According to an example, the detectable member 230 may be provided on at least one of a carrier and a plurality of frames coupled to the lens barrel 134 in addition to the lens barrel 134.

[0084] The detectable member 230 may include any one of a magnet and a conductor. For example, the detectable member 230 may correspond to Figure 1 The first magnet 121b or the second magnet 122b, and according to an example, additional elements may be provided to implement the detectable member 230.

[0085] The position detector 240 detects the position of the detectable member 230 that moves together with the lens barrel 134 through electromagnetic interaction between the magnet and the driving coil 220 to generate a feedback signal Sf and provide the feedback signal Sf to the driving device 210 .

[0086] The position detector 240 may include a position detection element and an analog-to-digital converter. The position detection element of the position detector 240 may correspond to Figure 1The position detecting element may detect the magnetic field strength of the detectable member 230 to detect the position of the lens barrel 134. The analog-to-digital converter may convert an analog signal output from the position detecting element into a digital signal.

[0087] When the feedback signal Sf is provided to the driving device 210, the driving device 210 can generate the driving signal Sdr again by comparing the input signal Sin with the feedback signal Sf. For example, the driving device 210 can be driven in a closed-loop method that compares the input signal Sin and the feedback signal Sf. The closed-loop driving device 210 can be driven in a direction that reduces the error between the target position included in the input signal Sin and the current position determined by the feedback signal Sf. Compared with the open-loop driving method, the closed-loop driving method has the advantages of improved linearity, accuracy and repeatability.

[0088] The driving device 210 may include an H-bridge circuit capable of driving in two directions therein to apply a driving signal to the driving coil 220 .

[0089] Figure 3 is a block diagram of a driving device 210 according to an example.

[0090] The driving device 210 may include, for example, a comparator 212 , a controller IC 214 , and a driving circuit 216 .

[0091] The comparator 212 can compare the input signal Sin with the feedback signal Sf. The comparator 212 can calculate the error value ERROR by comparing the target position of the lens barrel 134 included in the input signal Sin with the current position of the lens barrel 134 included in the feedback signal Sf. For example, the comparator 212 can compare the input signal Sin with the feedback signal Sf, and calculate the error value ERROR in sequence. The moving distance and moving direction of the lens barrel 134 can be determined by the error value ERROR calculated by the comparator 212.

[0092] The controller IC 214 may generate a control signal by applying a control gain to the error value ERROR provided by the comparator 212. As an example, the controller IC 214 may include a proportional integral derivative (PID) controller to perform a PID control operation. The controller IC 214 may generate a control signal by applying a control gain of the PID controller to the error value.

[0093] The controller IC 214 may perform a control operation proportional to the size of the error value (ERROR) in the current state according to proportional control, may perform a control operation according to integral control to reduce the error in a steady state, and may perform a control operation according to derivative control to reduce overshoot by preventing sudden changes.

[0094] The control of the PID controller can be expressed by the following equation 1. In equation 1, K P Represents the proportional control gain, K I represents the integral control gain, K D denotes a derivative control gain, and e(t) denotes a function representing a change in an error value (ERROR).

[0095] Equation 1

[0096]

[0097] When performing PID control operation, the controller IC 214 can control the proportional control gain K P , integral control gain K I And the differential control gain K D An error value ERROR corresponding to a difference between a target position of the lens barrel and a current position of the lens barrel 134 is applied to generate a control signal.

[0098] The driving circuit 216 may generate a driving signal in response to a control signal provided by the controller IC 214. The lens barrel 134 may be moved to a target position by the driving signal generated by the driving circuit 216. The driving circuit 216 may include an H-bridge circuit capable of bidirectional driving therein, thereby applying a driving signal to the driving coil 220 in a voice coil motor method. The driving signal may be provided to the driving coil 220 in the form of a current or a voltage.

[0099] When the driving circuit 216 is driven by the voice coil motor method, a control signal provided by the controller IC 214 may be applied to the control terminal of the transistor elements constituting the H-bridge circuit.

[0100] However, even when the control signal is generated by applying the control gain, the lens barrel 134 may not converge to the target position and oscillate. In this case, oscillation is a state in which the lens barrel 134 does not enter a steady state even after the stabilization time has passed, and overshoot or undershoot occurs continuously.

[0101] For example, depending on the guide grooves 131a / 131b / 132a ( Figure 1 ) and the ball bearings 141 / 142 / 143 ( Figure 1 ) may cause the lens barrel 134 to oscillate.

[0102] A lubricant including lubricating oil may be applied to the ball bearings 141 / 142 / 143 and the guide grooves 131a / 131b / 132a. For example, depending on a change in the lubricant applied to the ball bearings 141 / 142 / 143 and the guide grooves 131a / 131b / 132a, a friction coefficient between the ball bearings 141 / 142 / 143 and the guide grooves 131a / 131b / 132a may change. The lubricant may change depending on the amount of lubricant applied in the initial process or the amount of lubricant reduced according to use.

[0103] According to an example, the controller IC 214 may determine a control gain according to a change in the friction coefficient to suppress oscillation of the lens barrel 134 , and may quickly move the lens barrel 134 to a target position.

[0104] Figure 4 is a block diagram of the controller IC 214 according to an example.

[0105] refer to Figure 4 , the controller IC 214 may include a friction coefficient determiner 214a, a control gain determiner 214b, and a control signal generator 214c.

[0106] The friction coefficient determiner 214 a may determine the friction coefficient between the ball bearings 141 / 142 / 143 and the guide grooves 131 a / 131 b / 132 a . The friction coefficient determiner 214 a may control the driving circuit 216 to provide a detection signal to the driving coil 220 .

[0107] The friction coefficient determiner 214a can determine the friction coefficient between the ball bearing 141 / 142 / 143 and the guide groove 131a / 131b / 132a according to the level of the detection signal measured when the lens barrel 134 overcomes the static friction force and moves. In this case, the level of the detection signal corresponds to the current level or the voltage level. The movement of the lens barrel 134 can be measured by a position detector 240 including a Hall element that detects the position of the lens barrel 134.

[0108] The level of the detection signal may increase gradually or linearly. The level of the detection signal may increase from a preset reference level. In this case, the preset reference level may correspond to a zero level.

[0109] The friction coefficient determiner 214 a may determine the friction coefficient by modeling the level of the detection signal when the lens barrel 134 overcomes the static friction force and moves as the static friction force.

[0110] Since the static friction force is proportional to the friction coefficient and the normal force, assuming that the normal force is constant, when the level of the detection signal when the lens barrel 134 is moved is modeled as the static friction force, the friction coefficient between the ball bearing 141 / 142 / 143 and the guide groove 131a / 131b / 132a can be determined.

[0111] On the other hand, since the normal force changes according to the angle of the guide groove 131a / 131b / 132a of the contact ball support 141 / 142 / 143, it is necessary to correct the friction coefficient determined according to the level of the detection signal when the lens barrel 134 moves according to the angle information of the guide groove 131a / 131b / 132a.

[0112] The friction coefficient determiner 214a may receive a gyro signal Sgy including angle information of the guide grooves 131a / 131b / 132a. The gyro signal Sgy may be provided by a gyro sensor that detects shaking of the camera module 100 or an electronic device including the camera module 100.

[0113] Since the gyro sensor detects acceleration and angular velocity of the camera module 100 or an electronic device including the camera module 100, the gyro signal Sgy output from the gyro sensor may include angle information of the guide grooves 131a / 131b / 132a. Therefore, the friction coefficient determiner 214a may correct the friction coefficient according to the angle information of the guide grooves 131a / 131b / 132a provided by the gyro signal Sgy.

[0114] The control gain determiner 214b may determine the control gain according to the friction coefficient determined by the friction coefficient determiner 214a. For example, when the friction coefficient is greater than the reference friction coefficient, the control gain determiner 214b may increase the level of the control gain, and when the friction coefficient is less than the reference friction coefficient, the control gain determiner 214b may decrease the level of the control gain.

[0115] The control signal generator 214c may generate a control signal by applying the control gain determined by the control gain determiner 214b to the error value ERROR.

[0116] The lens barrel 134 may be quickly moved to a target position without oscillation by a control signal generated by the control signal generator 214 c .

[0117] As described above, according to the embodiments disclosed herein, a control gain is determined according to a friction coefficient between a guide groove for guiding movement of a lens barrel and a ball bearing in contact with the guide groove, thereby suppressing vibration of the lens barrel and quickly moving the lens barrel to a target position.

[0118] Perform the operations described in this application Figures 2 to 4 The position detector 240, comparator 212, controller IC 214, friction coefficient determiner 214a, control gain determiner 214b and control signal generator 214c in are implemented by hardware components, and the hardware components are configured to perform the operations performed by the hardware components described in this application. Where appropriate, examples of hardware components that can be used to perform the operations described in this application include controllers, sensors, generators, drivers, memories, comparators, arithmetic logic units, adders, subtractors, multipliers, dividers, integrators, and any other electronic components configured to perform the operations described in this application. In other examples, one or more of the hardware components that perform the operations described in this application are implemented by computing hardware (e.g., by one or more processors or computers). A processor or computer can be implemented by one or more processing elements, such as logic gate arrays, controllers and arithmetic logic units, digital signal processors, microcomputers, programmable logic controllers, field programmable gate arrays, programmable logic arrays, microprocessors, or any other device or combination of devices configured to respond and execute instructions in a prescribed manner to achieve a desired result. In one example, a processor or computer includes (or is connected to) one or more memories storing instructions or software executed by a processor or computer. The hardware components implemented by a processor or computer can execute instructions or software, such as an operating system (OS) and one or more software applications running on the OS, to perform the operations described in this application. The hardware components can also access, manipulate, process, create and store data in response to the execution of instructions or software. For simplicity, the singular term "processor" or "computer" can be used to describe the examples described in this application, but multiple processors or computers can be used in other examples, or the processor or computer can include multiple processing elements, or multiple types of processing elements, or both. For example, a single hardware component or two or more hardware components can be implemented by a single processor, or two or more processors, or a processor and a controller. One or more hardware components can be implemented by one or more processors, or a processor and a controller, and one or more other hardware components can be implemented by one or more other processors, or another processor and another controller. One or more processors, or a processor and a controller can implement a single hardware component, or two or more hardware components. The hardware components may have any one or more of different processing configurations, examples of which include a single processor, independent processors, parallel processors, single instruction single data (SISD) multiprocessing, single instruction multiple data (SIMD) multiprocessing, multiple instruction single data (MISD) multiprocessing, and multiple instruction multiple data (MIMD) multiprocessing.

[0119] Instructions or software for controlling computing hardware (e.g., one or more processors or computers) to implement hardware components and perform methods as described above can be written as computer programs, code segments, instructions, or any combination thereof, for individually or collectively instructing or configuring one or more processors or computers to operate as machines or special-purpose computers to perform operations performed by hardware components and methods as described above. In one example, the instructions or software include machine code directly executed by one or more processors or computers, such as machine code generated by a compiler. In another example, the instructions or software include high-level code executed by one or more processors or computers using an interpreter. Instructions or software can be written in any programming language based on the block diagrams and flow charts shown in the accompanying drawings and the corresponding descriptions in the specification, and the accompanying drawings and specification disclose algorithms for performing operations performed by hardware components and methods as described above.

[0120] Instructions or software for controlling computing hardware (e.g., one or more processors or computers) to implement hardware components and perform the methods described above, and any associated data, data files, and data structures, may be recorded, stored, or fixed in or on one or more non-transitory computer-readable storage media. Examples of non-transitory computer-readable storage media include read-only memory (ROM), random access memory (RAM), flash memory, CD-ROM, CD-R, CD+R, CD-RW, CD+RW, DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM, BD-ROM, BD-R, BD-R LTH, BD-RE, magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid-state disk, and any other device configured to store instructions or software and any associated data, data files, and data structures in a non-transitory manner and provide instructions or software and any associated data, data files, and data structures to one or more processors or computers so that one or more processors or computers can execute instructions. In one example, instructions or software and any associated data, data files, and data structures are distributed across a network-connected computer system so that the instructions and software and any associated data, data files, and data structures are stored, accessed, and executed in a distributed manner by one or more processors or computers.

[0121] Although the present disclosure includes specific examples, it will be apparent after understanding the disclosure of the present application that various changes in form and detail may be made to these examples without departing from the spirit and scope of the claims and their equivalents. The examples described in the present application are understood only in a descriptive sense, and not for limiting purposes. The description of the features or aspects in each example should be considered to be applicable to similar features or aspects in other examples. If the described techniques are performed in a different order, and / or if the components in the described system, architecture, device or circuit are replaced or supplemented in a different manner and / or by other components or their equivalents, appropriate results can still be achieved. In addition, various embodiments may be combined with each other. Therefore, the scope of the present disclosure is not limited by specific embodiments, but by claims and their equivalents, and all variations within the scope of claims and their equivalents should be understood to be included in the present disclosure.

Claims

1. An actuator for a camera module, comprising: A magnet is disposed on the lens barrel; A driving coil, arranged opposite to the magnet; as well as A driving device, comprising: a comparator, a controller IC, and a driving circuit, wherein the comparator is configured to calculate an error value by comparing a target position of the lens barrel with a current position of the lens barrel, the controller IC is configured to generate a control signal by applying a control gain to the error value, and the driving circuit is configured to generate a driving signal in response to the control signal. wherein the controller IC is further configured to determine the control gain based on a friction coefficient between a guide groove guiding movement of the lens barrel and a ball bearing contacting the guide groove, and The controller IC is further configured to provide a detection signal having a gradually increasing level to the drive coil, and determine the friction coefficient based on the level of the detection signal at a time point when the lens barrel moves.

2. The actuator according to claim 1, wherein: The control gain is provided by a PID controller.

3. The actuator according to claim 2, wherein: The controller IC is further configured to increase the control gain in response to the friction coefficient being greater than a reference friction coefficient, and to decrease the control gain in response to the friction coefficient being less than the reference friction coefficient.

4. The actuator according to claim 1, wherein: The controller IC is also configured to receive a gyroscope signal including angle information of the guide slot.

5. The actuator according to claim 4, wherein: The controller IC is further configured to correct the friction coefficient based on the angle information of the guide groove. 6 . The actuator according to claim 1 , further comprising a position detector including a Hall element configured to detect a position of the lens barrel.

7. The actuator according to claim 1, wherein: The guide groove and the ball bearing are configured to have a lubricant applied to the guide groove and the ball bearing.

8. The actuator according to claim 1, wherein: The controller IC is also configured to model a level of the detection signal at a point in time when the lens barrel moves as a static friction force.

9. The actuator according to claim 1, wherein: The drive circuit is further configured to provide the drive signal to the drive coil to perform any one of: moving the lens barrel in the optical axis direction for an autofocus function, and moving the lens barrel in a direction perpendicular to the optical axis direction for an image stabilization function.

10. An actuator for a camera module, comprising: A magnet is disposed on the lens barrel; A driving coil, arranged opposite to the magnet; as well as A driving device, comprising: a comparator, a controller IC, and a driving circuit, wherein the comparator is configured to calculate an error value by comparing a target position of the lens barrel and a current position of the lens barrel, the controller IC is configured to generate a control signal by applying a control gain to the error value, and the driving circuit is configured to generate a driving signal in response to the control signal to move the lens barrel to the target position, wherein the controller IC is further configured to determine the control gain based on a friction coefficient between a guide groove guiding movement of the lens barrel and a ball bearing contacting the guide groove, and The controller IC is further configured to provide a detection signal to the drive coil, and model a level of the detection signal at a time point when the lens barrel moves as a static friction force to determine the friction coefficient.

11. The actuator according to claim 10, wherein: The control gain is provided by a PID controller.

12. The actuator according to claim 11, wherein: The controller IC is further configured to increase the control gain in response to the friction coefficient being greater than a reference friction coefficient, and to decrease the control gain in response to the friction coefficient being less than the reference friction coefficient.

13. The actuator according to claim 10, wherein: The controller IC is also configured to receive a gyroscope signal including angle information of the guide slot.

14. The actuator according to claim 13, wherein: The controller IC is further configured to correct the friction coefficient based on the angle information of the guide groove. 15 . The actuator of claim 10 , further comprising a position detector including a Hall element configured to detect a position of the lens barrel.

16. The actuator according to claim 10, wherein: The guide groove and the ball bearing are configured to have a lubricant applied to the guide groove and the ball bearing.

17. The actuator according to claim 10, wherein: The detection signal has a gradually increasing level.

18. The actuator according to claim 10, wherein: The drive circuit is further configured to provide the drive signal to the drive coil to perform any one of: moving the lens barrel in the optical axis direction for an autofocus function, and moving the lens barrel in a direction perpendicular to the optical axis direction for an image stabilization function.

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