KR102218898B1 - Apparatus for controlling position of camera module - Google Patents

Abstract

A device for controlling a position of a camera module according to an embodiment of the present invention includes: a magnetic material disposed in a lens barrel of the camera module; A coil disposed opposite the magnetic body; A driver for providing a position identification signal including a specific frequency component to the coil; A signal extractor for extracting a detection signal including the specific frequency component from among the signals of the coil; A position detector that provides a position signal corresponding to the position of the magnetic body based on the detection signal; And a controller providing a feedback signal to the driver for controlling a position error based on the position signal and a position reference signal from the position detector. Includes.

Description

Position control device of camera module {APPARATUS FOR CONTROLLING POSITION OF CAMERA MODULE}

The present invention relates to an apparatus for controlling a position of a camera module.

In the case of a camera module for mobile phones recently, a slimmer and high-performance image is required. In order to satisfy these requirements, functions such as mounting of a lens with a high aperture ratio of the camera, autofocus and OIS (Optical Image Stabilizer) are required. However, in order to perform auto focus or OIS, it is necessary to determine an accurate position and to accurately detect a current position value.

As an existing technology, a method of performing position control using a Hall sensor and a position sensing magnet may be used.

In the case of using an existing Hall sensor, a separate magnet may be required, and in this case, the reference value for the location of the Hall sensor may change according to temperature or other external matters. For this, additional circuits such as a low pass filter, an auto gain control amplifier, a differential to single amplifier, or an analog to digital converter are required. There is a drawback.

In addition, when an external Hall sensor is used, a bias current (e.g., several mA) may be consumed to drive the Hall sensor, and additional current may be consumed by various amplifiers (AMP). There are drawbacks.

In order to solve problems such as mechanical design constraints, additional current consumption, and material cost increase of the camera module as described above, there is a need for a method capable of detecting and controlling a position without employing a Hall sensor.

Republic of Korea Patent Publication No. 2014-0088308

An object of the present invention is to provide an apparatus and method for controlling a position of a camera module that does not employ a separate sensing means such as a Hall sensor, and performs sensing and driving of a lens barrel through one coil.

According to an embodiment of the present invention, a magnetic material disposed on the lens barrel of the camera module; A coil disposed opposite the magnetic body; A driver for providing a position identification signal including a specific frequency component to the coil; A signal extractor for extracting a detection signal including the specific frequency component from among the signals of the coil; And a position detector that provides a position signal corresponding to the position of the magnetic body based on the detection signal. A device for controlling a position of a camera module including a is proposed.

According to another embodiment of the present invention, a magnetic material disposed on the lens barrel of the camera module; A coil disposed opposite the magnetic body; A driver for providing a position identification signal including a specific frequency component to the coil; A signal extractor for extracting a detection signal including the specific frequency component from among the signals of the coil; And a position detector that detects the magnitude of the impedance of the coil using the detection signal and the position identification signal, and provides a position signal corresponding to the position of the magnetic body based on the magnitude of the impedance of the coil. A device for controlling a position of a camera module including a is proposed.

In addition, according to another embodiment of the present invention, the magnetic material disposed on the lens barrel of the camera module; A coil disposed opposite the magnetic body; A driver for providing a position identification signal including a specific frequency component to the coil; A signal extractor for extracting a detection signal including the specific frequency component from among the signals of the coil; And a position detector that detects an angle of impedance of the coil using the detection signal and the position check signal, and provides a position signal corresponding to the position of the magnetic body based on the angle of the impedance of the coil. A device for controlling a position of a camera module including a is proposed.

According to an embodiment of the present invention, since a separate sensing means such as a Hall sensor is not employed, manufacturing cost can be reduced, space efficiency can be improved, power consumption can be reduced, and miniaturization is advantageous.

In addition, by performing sensing as well as driving through one coil, and performing closed-loop position control using a sensing method that does not affect the driving through one coil, more stable and precise position control can be performed. I can.

In addition, since defect elements and process processes that may occur during manufacturing are simplified, additional effects can be achieved in addition to direct effects. Since there is no separate sensing means, not only an auto focus (AF) actuator but also an OIS (Optical Image Stabilizer) actuator or There is an advantage that it can also be easily applied to the optical zoom function.

1 is an exploded perspective view of a camera module according to an embodiment of the present invention.
2 is an exemplary diagram of a device for controlling a position of a camera module according to an embodiment of the present invention.
3 is an exemplary circuit block diagram of the position control apparatus of the camera module of FIG. 2.
4 is an exemplary view of a driver according to an embodiment of the present invention.
(A), (b), (c) and (d) of FIG. 5 are diagrams illustrating the relative positions of a magnetic material with respect to a coil according to an embodiment of the present invention.
6 is an exemplary view of a position detector according to an embodiment of the present invention.
7 is another exemplary view of a position detector according to an embodiment of the present invention.
8 is an exemplary diagram of an overlapping signal, a position checking signal, a driving signal, a first detection signal, and a second detection signal according to an embodiment of the present invention.

Hereinafter, it is to be understood that the present invention is not limited to the described embodiments, and may be variously changed without departing from the spirit and scope of the present invention.

In addition, in each embodiment of the present invention, the structure, shape, and numerical values described as an example are only examples for helping the understanding of the technical matters of the present invention, and thus the spirit and scope of the present invention are not limited thereto. It should be understood that various changes can be made without departing. Embodiments of the present invention may be combined with each other to form various new embodiments.

In the drawings referred to in the present invention, components having substantially the same configuration and function in light of the overall contents of the present invention will be denoted by the same reference numerals.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to allow those of ordinary skill in the art to easily implement the present invention.

1 is an exploded perspective view of a camera module according to an embodiment of the present invention.

Referring to FIG. 1, a camera module 100 according to an embodiment of the present invention includes a case 110, a housing 120, a lens barrel 130, a substrate 140, a coil 150, and a magnetic body 160. ) Can be included.

In addition, the camera module 100 may further include a ball bearing 135.

1 illustrates a ball bearing type camera module employing a ball bearing, but the present invention is not limited thereto, and may be applied to a spring type camera module as an example.

The lens barrel 130 may have a hollow cylindrical shape such that at least one lens for capturing a subject is accommodated therein, and a lens is provided in the lens barrel 130 along an optical axis. Here, the optical axis direction means the Z axis direction based on the lens barrel 130 shown in FIG. 1.

The lens barrel 130 is disposed inside the housing 120 and coupled to the housing 120, and can be moved in the optical axis direction for autofocusing, and a direction perpendicular to the optical axis for OIS (Optical Image Stabilizer) (Fig. 1). Can move in the X-axis direction or Y-axis direction).

The housing 120 includes an inner space, and the lens barrel 130 may be accommodated in the inner space of the housing 120 so that the lens barrel 130 is movable in the optical axis direction or in a direction perpendicular to the optical axis.

As a guide means for guiding the movement of the lens barrel 130 when the lens barrel 130 moves in the optical axis direction within the housing 120, the lens barrel 130 includes at least one ball bearing 135 along the optical axis direction. Can be provided.

At least one ball bearing 135 is disposed between the lens barrel 130 and the housing 120 so that one surface of the lens barrel 130 and one surface of the housing 120 are in contact with each other, and the lens barrel 130 While supporting ), it is possible to guide the movement of the lens barrel 130 in the optical axis direction.

The case 110 may be combined with the housing 120 to form the exterior of the camera module. The case 110 may be coupled to the housing 120 to surround a part of the outer surface of the housing 120. The case 110 may include a metal material or be made of a metal material and may be grounded to a ground pad of a substrate mounted under the housing 120, thereby shielding electromagnetic waves generated during driving of the camera module. .

The magnetic body 160 may be disposed on one side of the lens barrel 130, and the coil 150 may be disposed on one side of the substrate 140 mounted on the housing 120 to face the magnetic body 160. As an example, the magnetic body 160 may be a magnet including a magnetic material having a magnetic property, or may be a conductor.

Although not shown in FIG. 1, a stopper is additionally disposed between the case 110 and the lens barrel 130 to limit the moving distance of the lens barrel 130. In addition, the camera module 100 may further include a yoke mounted on the other surface of the substrate 140 to prevent leakage of magnetic flux generated between the magnetic body 160 and the coil 150.

In an embodiment of the present invention, a structure using an alternating current as a position confirmation signal and a detection voltage as a detection signal is described, but the present invention is not limited thereto. It can be a structure using an alternating current as a signal.

In each of the drawings of the present document, unnecessary and redundant descriptions of components having the same reference numerals and the same functions may be omitted, and each drawing describes possible differences.

2 is an exemplary diagram of an apparatus for controlling a position of a camera module according to an exemplary embodiment of the present invention, and FIG. 3 is a circuit block diagram of an apparatus for controlling a position of the camera module of FIG. 2.

2 and 3, an apparatus for controlling a position of a camera module according to an exemplary embodiment of the present invention will be described.

The position control device of the camera module may include a coil 150, a magnetic body 160, a driver 200, a signal extractor 300, and a position detector 400. In addition, the device for controlling the position of the camera module may further include a controller 500.

The coil 150 is disposed on one surface of the substrate 140 (FIG. 1) mounted on the housing 120 (FIG. 1) to face the magnetic body 160, and can provide a driving force to the magnetic body 160 by electromagnetic force. It is spaced apart from the magnetic body 160 so that.

The magnetic body 160 may be disposed on one side of the lens barrel 130 and may be moved according to a driving force by the coil 150.

The driver 200 may provide a position check signal Sm to the coil 150. The positioning signal Sm may include a specific frequency component Fmod. The specific frequency component Fmod is a frequency capable of measuring the amount of change in impedance of the coil 150 without affecting the driving of the lens barrel 130, and for example, may be a frequency higher than the audible frequency.

As an example, the driver 200 may provide a position check signal Sm to the coil 150 independently of the driving signal Sdrv. As another example, in order to control the closed loop position more accurately and quickly, the driver 200 provides a superimposed signal SDRV in which the position checking signal Sm and the driving signal Sdrv are overlapped to the coil 150 can do.

As an example, the positioning signal Sm is an AC signal including at least one specific frequency component Fmod, for example, a sinusoidal wave signal, a triangle wave signal, a sawtooth wave ) Signal or a square wave signal.

In each embodiment of the present invention, the signal Sm for positioning is not limited to the above-described signal, and may include any AC signal including a specific frequency component.

For example, when the driver 200 applies a driving signal Sdrv to the coil 150, an electromagnetic force is generated as a current flows through the coil 150, and a driving force is provided to the magnetic body 160 by this electromagnetic force. I can.

That is, the driver 200 may apply a driving signal to the coil 150 to provide a driving force to the magnetic body 160. For example, when the driver 200 applies the driving signal Sdrv to the coil 150, a magnetic field is generated in the coil 150, and the magnetic field generated in the coil 150 interacts with the magnetic field of the magnetic body 160 , In accordance with Fleming's left-hand rule, a driving force for moving the lens barrel 130 in the optical axis direction (or perpendicular to the optical axis) may be generated.

Accordingly, the lens barrel 130 may move in the optical axis direction or in a direction perpendicular to the optical axis by the driving force.

For example, the driver 200 may include a driver IC (Driver Integrated Circuit) that provides a driving signal to the magnetic body 160.

For example, when the overlapping signal SDRV is an overlapping current IDRV, the driving signal Sdrv may be a direct current (DC) current generated by the driver 200 to drive the lens barrel 130. . The positioning signal Sm is generated by the driver 200 to check the position of the lens barrel 130, and may be an alternating current (AC) current having the specific frequency component Fmod. The detection signal Sd is a signal extracted from the signal SD of the coil 150 and may be an alternating current (AC) voltage having the specific frequency component Fmod.

For example, when the overlapping signal SDRV is the overlapping current IDRV, it may be expressed according to Equation 1 below.

[Equation 1]

In Equation 1, Idrv is a direct current driving current corresponding to the driving signal Sdrv, im is a current for positioning AC corresponding to the position checking signal Sm, and k*sin(2*π) *Fmod*t) can be defined. And, k is the amplitude of the current for positioning.

The size k and the frequency Fmod of the positioning signal Sm may be a range in which the amount of change in the inductance of the coil 150 can be measured without affecting the driving of the lens barrel 130. As an example, the size k of the positioning signal Sm is smaller than the size of the driving signal so as not to affect the driving of the lens barrel 130, and the frequency Fmod of the positioning signal Sm is It should not affect the driving of the lens barrel 130, here, that does not affect the driving means that the frequency must not cause the movement or resonance of the lens barrel.

For example, the size k of the positioning signal Sm is smaller than that of the driving signal, and the frequency Fmod of the positioning signal Sm is higher than the audible frequency. For example, when the size of the driving signal is 100 mA, the size k of the position check signal Sm may be 5 mA, and the frequency Fmod of the position check signal Sm may be 100 kHz.

The signal extractor 300 may extract a detection signal Sd including the specific frequency component Fmod from among the signals SD of the coil 150.

For example, the signal extractor 300 may include a filter capable of extracting an AC detection signal Sd including a specific frequency component Fmod.

The overlapping signal SDRV may be an overlapping current or an overlapping voltage. For example, when the overlapping signal SDRV is the overlapping current IDRV, when the overlapping current IDRV flows through the coil 150, a signal extractor ( 300) may extract the detection voltage Vd of the alternating current from the voltage across the coil 150 (VL of Equation 2 below).

The position detector 400 may provide a position signal Sp corresponding to the position of the magnetic body 160 based on the detection signal Sd.

The position detector 400 detects the impedance ZL of the coil 150 using the detection signal Sd and the position confirmation signal Sm, and based on the impedance of the coil 150, the A position signal Sp corresponding to the position of the magnetic body 160 may be provided. That is, the position detector 400 may detect the position of the magnetic body 160 according to the impedance of the coil 150 that changes according to the movement of the magnetic body 160.

For example, when the detection signal Sd is the detection voltage Vd and the position check signal Sm is the position check current im, the ratio of the detection voltage Vd and the position check current im The impedance of the coil 150 can be calculated.

As described above, the position detector 400 may detect the position of the lens barrel 130 that is moved by the driving of the driver 200, specifically, the magnetic body 160 provided on one side of the lens barrel 130. I can. The position detector 400 may provide a position signal Sp corresponding to the detected position of the magnetic body 160 to the controller 500.

In this case, the position detector 400 may detect the position of the lens barrel 130 by calculating the magnitude and angle of the impedance of the coil 150, which will be described with reference to FIGS. 6 and 7.

The controller 500 may provide a feedback signal Sf for controlling a position error based on the position signal Sp and the position reference signal Sref from the position detector 400 to the driver 200. have.

For example, the controller 500 compares the position signal Sp provided from the position detector 400 and the position reference signal Sref, and the position corresponding to the difference between the position signal Sp and the position reference signal Sref By providing a feedback signal Sf for compensating for an error to the driver 200, the position of the magnetic body 160 can be precisely controlled.

For example, the driver 200, the signal extractor 300, the position detector 400, and the controller 500 may be mounted on the substrate 140, and may be mounted on a specific substrate separate from the substrate 140, The substrate 140 or a specific substrate may be an FPCB (Flexible Printed Circuit Board), and the substrate 140 may be disposed on the housing 120 as shown in FIG. 1. 130) can be disposed in the inner hollow.

Here, the specific substrate does not need to be limited in a specially disposed position, and may be disposed inside the camera module.

In addition, the driver 200, the signal extractor 300, the position detector 400, and the controller 500 may be implemented as one integrated circuit (IC) according to the needs of the manufacturer and may be disposed on one substrate, and two It may be implemented with more than one integrated circuit and disposed on one substrate or two or more substrates. Such an integrated circuit is not limited to a specific location and may be disposed.

Referring to FIG. 3, the coil 150 is shown as a resistance component (Rs) and an inductance component (Lx), and the coil 150 is connected to a plurality of switching elements (see FIGS. 3 and 4) to drive voice An overlapping signal (SDRV=Sdrv(DC)+Sm(AC)) may be applied in a voice coil motor method.

Thereafter, the driver 200 may adjust the control signal VDRV according to the feedback signal Sf provided from the controller 500 to correct the driving signal Sdrv, and accordingly provide it to the coil 150 The position of the lens barrel 130 can be accurately adjusted.

For example, the driver 200 may include an operational amplifier OP1, a first low-side switch SL1 (eg, MOS transistor), and a resistor Rsen, and may further include a gain adjustment unit G. I can.

When the control signal VDRV input to the operational amplifier is the control voltage and the overlap signal SDRV is the overlap current IDRV, the overlap current IDRV flowing through the resistor Rsen is determined according to the control voltage. The voltage across the resistor Rsen may be determined by the overlapping current IDRV. Here, the control voltage VDRV may be equal to a product of an overlap current IDRV, a resistance Rsen, and a gain. For example, when the gain of the gain adjustment unit G is 1, the voltage across the resistor Rsen may be the same as the control voltage VDRV. Here, the resistance Rsen may be an actual resistance component or equivalent. It can be a circuit.

In addition, the driver shown in FIG. 3 is only one example of a feedback structure by converting a current signal into a signal in the form of a voltage using a resistor Rsen, and the driver according to an embodiment of the present invention is shown in FIG. It is not limited to the structure shown in FIG. 6, and a structure for copying a current signal without a resistor Rsen may be used.

4 is an exemplary view of a driver according to an embodiment of the present invention.

3 and 4, the driver 200 may include a full bridge circuit capable of bidirectional driving. As an example of the present invention, a full bridge circuit will be described as an example, but the present invention is not limited thereto.

The full bridge circuit includes a first leg LG1 including a first high-side switch SH1 and a first low-side switch SL1 connected in series between a power supply terminal VDD and a ground, It may include a second leg LG2 including a second high-side switch SH2 and a second low-side switch SL2 connected in series between the power terminal VDD and the ground.

Here, the first low-side switch SL1 may be included in the driver 200 as illustrated in FIG. 3, and may not be included as illustrated in FIG. 4.

At this time, between the connection node N between the first high-side switch SH1 and the first low-side switch SL1 and the connection node P between the second high-side switch SH2 and the second low-side switch SL2. The coil 150 is connected to.

In this case, when the first high-side switch SH1 and the second low-side switch SL2 are in an off state, and the second high-side switch SH2 and the first low-side switch SL1 are on, , A driving signal may flow to the coil 150 from the second high-side switch SH2 to the first low-side switch SL1. In this case, the driver 200 connected to the first low-side switch SL1 may adjust a driving signal flowing through the coil 150. Alternatively, although not shown in the drawing, the driver 200 may be connected to a second high-side switch.

In contrast, when the first high-side switch SH1 and the second low-side switch SL2 are turned on, and the second high-side switch SH2 and the first low-side switch SL1 are off, , A driving signal may flow to the coil 150 from the first high-side switch SH1 to the second low-side switch SL2. In this case, a driver (not shown) connected to the second low-side switch SL2 may adjust a driving signal flowing through the coil 150. Alternatively, although not shown in the drawing, the driver may be connected to the first high-side switch.

As described above, a driving signal may be applied to the coil 150 in both directions, and a driving force by the coil 150 may be generated in both directions according to the driving signal in both directions, and accordingly, the coil 150 The lens barrel may be moved along the optical axis direction or along the vertical direction of the optical axis according to the bidirectional driving force.

In an embodiment of the present invention, when the position check signal Sm is an alternating current position check current im, and the detection signal Sd is an alternating current detection voltage Vd, the driver 200 When an AC current for positioning an AC is applied to the coil 150, the impedance of the coil 150 can be measured by measuring the detection voltage Vd of the AC across the coil 150.

Accordingly, at the first position of the lens barrel 130, the first detection voltage Vd1 of the alternating current at both ends of the coil 150 when the current im for determining the position of alternating current is applied to the coil (Vd1, FIG. Thereafter, at the second position of the lens barrel 130 moved from the first position, the second detection voltage of the alternating current at both ends of the coil 150 when an alternating current position checking current im is applied to the coil 150 ( Vd2 (FIG. 8) is different from each other, and accordingly, the position of the lens barrel can be recognized by detecting an AC detection voltage across the coil 150.

Here, the amount of change in the impedance of the coil is generated due to the change in the magnetic field and the eddy current due to changes in the distance and overlap area between the coil 150 and the magnetic body 160, and this is the amplitude, maximum value, phase, and Or, it is caused by differences such as the root mean square (RMS).

Accordingly, the position detector 400 may detect a change in impedance of the coil 150 for position recognition based on the detection signal extracted by the signal extractor 300.

When explaining the principle of position detection according to an embodiment of the present invention, in the camera module according to an embodiment of the present invention, when driving, the coil 150 and the magnetic body 160 basically form a static magnetic field. I can. At this time, when the AC position check signal Sm is applied to the coil, the magnetic field is changed into a dynamic magnetic field, and an eddy current is generated in the magnetic body 160 by the dynamic magnetic field as described above.

Here, eddy current (or eddy current) occurs when a magnetic field that changes over time passes through a conductor, and when the magnetic field changes, a circulating current of electrons occurs in the conductor. This circulating current is called eddy current. It is called. This eddy current has a direction that interferes with the change of the magnetic field passing through the magnetic body. Eddy current occurs when a magnetic body (or conductor) moves within a magnetic field or when a changing magnetic field passes through a static conductor. It also appears when a magnetic body (or conductor) moves in a changing magnetic field. That is, when there is a change in the strength or direction of the magnetic field, an eddy current may occur in any part of the magnetic field except for the boundary point of the magnetic material (or conductor).

Subsequently, when a difference occurs in the distance or overlapping area between the coil 150 and the magnetic body 160, the eddy current in the magnetic body 160 changes, and the magnetic field according to the change in the eddy current The change of is to affect the coil, resulting in a change in the impedance of the coil.

For example, the eddy current of the magnetic material and the change in the magnetic field generated by the signal for confirming the location of the alternating current change according to the relative position (e.g., gap or area) between the coil and the magnetic material. Is reflected in the impedance of

As described above, a change in a magnetic field or a change in an eddy current occurs due to a change in an interval and an overlap area between the coil 150 and the magnetic body 160, and accordingly, an impedance change amount of the coil is generated.

An example of the overlap area between the coil 150 and the magnetic body 160 will be described with reference to FIGS. 5A, 5B, 5C, and 5D.

(A), (b), (c), and (d) of FIG. 5 are exemplary diagrams and positions in the axial direction of a coil and a magnetic material according to an embodiment of the present invention.

Figure 5 (a) is an example of the X-axis, Y-axis, and Z-axis for a coil and a magnetic material according to an embodiment of the present invention, Figure 5 (b) is a coil according to an embodiment of the present invention. A magnetic body is an example of a fixed position, and (c) of FIG. 5 is an example of a position in which the magnetic body is moved upward in the Z-axis direction with respect to a coil according to an embodiment of the present invention, and FIG. It is an exemplary diagram of a position in which a magnetic material moves downward in a Z-axis direction with respect to a coil according to an embodiment of the present invention.

Referring to Figure 5 (a), as shown in Figure 1, the coil 150 and the magnetic body 160 are disposed opposite to each other, the Z axis is the optical axis direction, the X axis and the Y axis are modified It can be defined as a direction.

The magnetic body 160 shown in (b) of FIG. 5 may be positioned at a position corresponding to a preset default value, and in this case, the overlap area between the coil and the magnetic body determining the driving force is an area It could be A1.

The magnetic body 160 shown in (c) of FIG. 5 may be located at a position that is upwardly moved in the Z-axis direction by a driving signal of the coil 150 in the first direction. In this case, the coil 150 and the magnetic body The overlap area between the coil and the magnetic body, which determines the strength of the electromagnetic field between 160, may be changed to become an area A2 smaller than the area A1.

The magnetic body 160 shown in (d) of FIG. 5 may be located at a position moved downward in the Z-axis direction by a driving signal of the coil 150 in the second direction. In this case, the coil 150 and the magnetic body The overlap area between the coil and the magnetic body, which determines the strength of the electromagnetic field between 160, may be changed to become an area A3 smaller than the area A1.

As described above, when the magnetic body 160 moves in the Z-axis direction, since the overlapping area with the coil 150 changes to A1, A2 or A3, the electromagnetic field strength between the coil 150 and the magnetic body 160 Is changed, and accordingly, the inductance of the coil 150 may be changed.

In this way, while supplying the current for checking the position of AC as a driving signal to the coil 150, when the impedance of the coil 150 is changed, the AC voltage at both ends of the coil 150 changes the impedance of the coil 150 Subject to change.

According to an embodiment of the present invention, in order to increase the rate of change of the inductance of the coil 150 according to the positional movement of the magnetic body 160, the magnetic body 160 and the coil 150 are formed of a magnetic material and a magnetic material having a high permeability. Paint can be formed.

For example, when the driving signal SDRV is the driving current IDRV, the signal extractor 300 extracts a detection voltage Vd including a specific frequency component Fmod from the signal of the coil 150 to detect the position. It can be provided to 400.

The position detector 400 uses the position checking current im included in the driving current IDRV and the detection voltage Vd to determine the impedance (ZL) magnitude (|ZL|) or the impedance angle ( θ) can be detected, and the position of the magnetic body 160, that is, the position of the lens barrel 130, is detected using the magnitude (|ZL|) and the impedance angle (θ) of the impedance (ZL) of the coil 150 can do.

6 is an exemplary view of a position detector according to an embodiment of the present invention.

Referring to FIG. 6, the position detector 400 may include an amplitude detector 410.

For example, the amplitude detector 410 uses the detection signal Sd from the signal extractor 300 and the position check signal Sm to determine the magnitude of the impedance ZL of the coil 150 (|ZL ｜) may be detected, and a position signal Sp corresponding to the position of the magnetic body 160 may be provided based on the magnitude of the impedance of the coil 150 (|ZL|).

In this case, the impedance magnitude (|ZL|) may be expressed according to Equation 2 below.

[Equation 2]

In Equation 2, VL is the voltage across the coil, IDRV is the superimposed current flowing through the coil, and |ZL| is the impedance of the coil.

In addition, the magnitude of the impedance of the coil 150 (|ZL|) may be expressed according to Equation 3 below.

[Equation 3]

In Equation 3, Rs is a resistance component of the coil 150, Lx is an inductance component of the coil 150, and Fmod is a specific frequency component, and Fmod may be equal to or greater than the audible frequency.

As an example, the amplitude detector 410 may include an amplifying circuit for amplifying the amount of change in inductance since the amount of change in the inductance of the coil 150 is very small.

7 is another exemplary view of a position detector according to an embodiment of the present invention.

Referring to FIG. 7, the position detector 400 may include a phase detector 420.

The phase detector 420 detects the angle θ of the impedance ZL of the coil 150 using the detection signal Sd from the signal extractor 300 and the position check signal Sm. The position signal Sp corresponding to the position of the magnetic body 160 may be provided based on the angle θ of the impedance of the coil 150.

The phase detector 420 may detect the position of the magnetic body 160 from a change in the angle θ of the impedance of the coil 150.

Here, the impedance angle θ may be expressed according to Equation 4 below.

[Equation 4]

For example, when the position check signal Sm is an AC current im and the detection signal Sd is an AC voltage Vd, the phase detector 420 is a detection voltage from the signal extractor 300 It is possible to detect a phase difference between (Vd) and the position checking current (im).

For example, the phase detector 420 may output a pulse signal having a pulse width corresponding to the phase difference.

For example, the amplitude of the pulse may be determined according to the phase difference between the detection voltage Vd and the position checking current im. For example, the phase detector 420 may include a zero-crossing circuit to measure the phases of the detection voltage Vd and the positional current im.

8 is an exemplary diagram of an overlapping signal, a position checking signal, a driving signal, a first detection signal, and a second detection signal according to an embodiment of the present invention.

In FIG. 8, IDRV is an overlapping current corresponding to the overlapping signal SDRV, im is a positioning current corresponding to the positioning signal Sm, and Idrv is a driving current corresponding to the driving signal Sdrv, Vd1 and Vd2 are different first detection voltages and second detection voltages corresponding to detection signals Sd extracted from the signal extractor 300.

As described above, in each embodiment of the present invention, specific matters such as specific components, etc., and limited embodiments and drawings have been described, but this is provided only to aid in a more general understanding of the present invention. It is not limited to the embodiments, and those of ordinary skill in the art to which the present invention pertains can make various modifications and variations from these descriptions.

Therefore, the spirit of the present invention is limited to the above-described embodiments and should not be determined, and all modifications that are equally or equivalent to the claims as well as the claims to be described later fall within the scope of the spirit of the present invention. I would say.

100: camera module
130; Lens barrel
150: coil
160: magnetic body
200: actuator
300: signal extractor
400: position detector
Sm: Signal for positioning
Fmod: specific frequency component
Sd: detection signal
Sp: position signal
Sdrv: drive signal
SDRV: superimposed signal

Claims (13)

A position control device applied to a camera module including a magnetic body disposed on a lens barrel and a coil disposed opposite the magnetic body,
By using a closed loop current control circuit, a superimposed signal including a driving signal and a position checking signal superimposed with each other is generated, and the superimposed signal is provided to the coil, and the position checking signal includes a specific frequency component. Actuator;
A signal extractor for extracting a detection signal including the specific frequency component from among the signals of the coil;
A position detector that provides a position signal corresponding to the position of the magnetic body based on the detection signal; And
A controller providing a feedback signal to the driver for controlling a position error based on the position signal and a position reference signal from the position detector; Including,
The driver includes an operational amplifier included in the closed loop current control circuit, a first low-side switch, a resistor, and a gain control unit,
The operational amplifier provides a current flowing through the first low-side switch based on an input control signal and a voltage provided from the gain adjustment unit,
The resistor converts the current flowing through the first low-side switch into a voltage at both ends and provides the gain control unit.
Camera module position control device.
delete The method of claim 1, wherein the position detector,
Detecting the impedance of the coil using the detection signal and the position checking signal, and providing a position signal corresponding to the position of the magnetic body based on the impedance of the coil
Camera module position control device.
The method of claim 1,
The driving signal is a direct current,
The positioning signal is an AC current having the specific frequency component,
The detection signal is an AC voltage having the specific frequency component.
delete A magnetic material disposed on the lens barrel of the camera module;
A coil disposed opposite the magnetic body;
By using a closed loop current control circuit, a superimposed signal including a driving signal and a position checking signal superimposed with each other is generated, and the superimposed signal is provided to the coil, and the position checking signal includes a specific frequency component. Actuator;
A signal extractor for extracting a detection signal including the specific frequency component from among the signals of the coil;
A position that detects the magnitude or impedance angle of the impedance of the coil using the detection signal and the position confirmation signal, and provides a position signal corresponding to the position of the magnetic body based on the magnitude or impedance angle of the coil Detector; And
A controller providing a feedback signal to the driver for controlling a position error based on the position signal and a position reference signal from the position detector; Including,
The driver includes an operational amplifier included in the closed loop current control circuit, a first low-side switch, a resistor, and a gain control unit,
The operational amplifier provides a current flowing through the first low-side switch based on an input control signal and a voltage provided from the gain adjustment unit,
The resistor converts the current flowing through the first low-side switch into a voltage at both ends and provides the gain control unit.
Camera module position control device.
delete The method of claim 6,
The driving signal is a direct current,
The positioning signal is an AC current having the specific frequency component,
The detection signal is an AC voltage having the specific frequency component.
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