KR102117462B1 - Actuator and position control apparatus of voice coil moto with temperature compensation function - Google Patents

Abstract

An actuator of the VCM method according to an embodiment of the present invention, the coil is spaced apart from the magnetic body provided on one side of the lens carrier; A driving circuit for applying an overlapping current including a driving current and a position detecting current to the coil based on the input overlapping voltage; And a low-frequency signal having an inductance component of the coil by converting an AC voltage signal including a specific frequency component obtained at both ends of the coil to a demodulation technique, and detecting a position signal based on the low-frequency signal/ Digital conversion circuit; It may include.

Description

Actuator and position control device with temperature compensation function{ACTUATOR AND POSITION CONTROL APPARATUS OF VOICE COIL MOTO WITH TEMPERATURE COMPENSATION FUNCTION}

The present invention relates to a voice coil motor type actuator and a position control device having a temperature compensation function.

Recently, a camera module for a mobile phone requires a slimmer and higher-performance image. In order to satisfy these needs, it is necessary to install a lens with a high aperture ratio of the camera, functions such as autofocus and optical image stabilizer (OIS). However, in order to perform autofocus or OIS, it is necessary to accurately detect the current position value.

As a conventional technique, a method of performing position detection and position control using a Hall sensor and a magnet for position sensing may be used.

When using the existing Hall sensor, a separate magnet may be required, and in this case, the reference value for the position of the Hall sensor may be changed depending on temperature or other external factors, to correct it For this, additional circuits such as a low pass filter, an auto gain control amplifier, a differential to single amplifier or an analog/digital converter are required. There are disadvantages.

In addition, when an external Hall sensor is used, bias current (eg, several mA) may be consumed to drive the Hall sensor, and current by various amplifiers AMP may be additionally consumed. There are disadvantages.

In order to solve the problems such as mechanical design constraints of the camera module, additional current consumption, and material cost increase, a method capable of position detection and position control without employing a separate sensor such as a Hall sensor This is necessary.

(Advanced technical literature)

(Patent Document) KR 2014-0088308 A

According to an embodiment of the present invention, by using the I/Q demodulation technique to exclude parasitic resistance components of a coil sensitive to temperature change from signal processing, a VCM method capable of more accurately detecting the lens position of a more accurate VCM camera Provides actuators and position control devices.

According to an embodiment of the present invention, the coil is spaced apart from the magnetic body provided on one side of the lens carrier; A driving circuit for applying an overlapping current including a driving current and a position detecting current to the coil based on the input overlapping voltage; And a low-frequency signal having an inductance component of the coil by converting an AC voltage signal including a specific frequency component obtained at both ends of the coil to a demodulation technique, and detecting a position signal based on the low-frequency signal/ Digital conversion circuit; An actuator of the VCM method including a is proposed.

The impedance/digital conversion circuit may be configured to compensate for temperature fluctuations caused by the resistance component by removing a high frequency signal having a resistance component of the coil converted by the demodulation technique.

The impedance/digital conversion circuit includes: a first filter for extracting the AC voltage signal from both ends of the coil; A demodulator that demodulates the AC voltage signal extracted from the first filter to provide a demodulation signal including a high frequency signal having a resistance component of the coil and a low frequency signal having an inductance component of the coil; A second filter for blocking the high frequency signal included in the demodulation signal and extracting the low frequency signal; A voltage control oscillator for converting the low frequency signal extracted from the second filter into a frequency signal based on its magnitude; And a digital filter for extracting a frequency component of the frequency signal and detecting the location signal including location information based on the frequency component. It may include.

The demodulator includes a local oscillator including a frequency equal to a specific frequency component of the AC voltage signal and generating a local oscillation signal having a phase difference of 90 degrees from the AC voltage signal; And a mixer that mixes the AC voltage signal and the local oscillation signal to provide the demodulation signal. It may include.

The local oscillator, when the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', the local oscillation signal is a sine wave signal'sin(ω) having a 90 degree phase difference from the AC voltage signal. *t)'.

The local oscillator, when the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', is the cosine wave signal'cos(180) having a phase difference of 180 degrees from the AC voltage signal as the local oscillation signal. ω*t)'.

In addition, according to another embodiment of the present invention, a superimposed current including a driving current and a current for position detection is applied to a coil that is spaced apart from a magnetic material provided on one side of a lens carrier, based on an input superimposed voltage. Driving circuit; The AC voltage signal including a specific frequency component obtained at both ends of the coil is converted to a demodulation technique to block a high frequency signal having a resistance component of the coil, extract a low frequency signal having an inductance component of the coil, , An impedance/digital conversion circuit that compensates for temperature fluctuations caused by parasitic resistance of the coil and detects a position signal based on the extracted low frequency signal; And a control circuit for controlling the driving circuit based on a position signal including position information from the impedance/digital conversion circuit and a control signal for control to a target position. A VCM type position control device is proposed.

The control circuit may be configured to provide the driving circuit with the superimposed voltage including a driving voltage for driving and a voltage for positioning based on the position signal and the control signal.

The impedance/digital conversion circuit includes: a first filter for extracting the AC voltage signal from both ends of the coil; A demodulator that demodulates the AC voltage signal extracted from the first filter to provide a demodulation signal including a high frequency signal having a resistance component of the coil and a low frequency signal having an inductance component of the coil; A second filter for blocking the high frequency signal included in the demodulation signal and extracting the low frequency signal; A voltage control oscillator for converting the low frequency signal extracted from the second filter into a frequency signal based on its magnitude; And a digital filter for extracting a frequency component of the frequency signal and detecting the location signal including location information based on the frequency component. It may include.

The demodulator includes a local oscillator including a frequency equal to a specific frequency component of the AC voltage signal and generating a local oscillation signal having a phase difference of 90 degrees from the AC voltage signal; And a mixer that mixes the AC voltage signal and the local oscillation signal to provide the demodulation signal. It may include.

The local oscillator, when the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', the local oscillation signal is a sine wave signal'sin(ω) having a 90 degree phase difference from the AC voltage signal. *t)'.

The local oscillator, when the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', the cosine wave signal'cos having a 180 degree phase difference from the AC voltage) signal as the local oscillation signal (ω*t)'.

According to an embodiment of the present invention, in the absence of a separate mechanism or circuit other than a driving coil, a separate sensor such as a Hall sensor is unnecessary, so that cost down, module size reduction, Effects such as reduction of defects and reduction of processes appear.

In addition, when the temperature is measured using a temperature sensor in the conventional IC, the coil temperature is indirectly measured as the temperature of the IC, but when applying an embodiment of the present invention, the coil is used as a temperature sensor, and the coil Through the compensation for the effect of the temperature, it has the advantage that more accurate position detection is possible.

In addition, there is an advantage that an existing AF control system can be used without modification since no additional sensor is required.

1 is a partially exploded perspective view of a voice coil motor (VCM) type camera module according to an embodiment of the present invention.
2 is an exemplary view of a voice coil motor (VCM) type actuator and a position control circuit according to an embodiment of the present invention.
3 is an exemplary diagram of an impedance/digital conversion circuit according to an embodiment of the present invention.
4 is an exemplary view of the demodulator of FIG. 3.
5 is another exemplary view of the demodulator of FIG. 3.
6 is another exemplary view of the demodulator of FIG. 3.

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

In addition, in each embodiment of the present invention, the structures, shapes, and numerical values described as one example are only examples to help understanding the technical matters of the present invention, and are not limited thereto, but 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 can be combined with each other to form a number of new embodiments.

In addition, in the drawings referred to the present invention, in view of the overall contents of the present invention, components having substantially the same configuration and function will use the same reference numerals.

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

1 is a partially exploded perspective view of a voice coil motor (VCM) type camera module according to an embodiment of the present invention.

1, the camera module 100 according to an embodiment of the present invention, the upper case 110, the housing 120, the lens carrier 130, the substrate 140, the coil 150 and the magnetic body ( 160). In addition, the camera module 100 may further include a ball bearing 135.

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

The lens carrier 130 may have a hollow shape so that at least one lens for photographing a subject can be accommodated therein, and a lens may be provided along the optical axis inside the lens carrier 130. Here, the optical axis direction refers to the Z-axis direction based on the lens carrier 130 shown in FIG. 1.

The lens carrier 130 is disposed inside the housing 120 and coupled with the housing 120, can move in the optical axis direction for autofocusing, and is perpendicular to the optical axis for OIS (Optical Image Stabilizer) (FIG. 1 (X-axis direction or Y-axis direction).

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

When the lens carrier 130 moves in the optical axis direction within the housing 120, as a guide means for guiding the movement of the lens carrier 130, the lens carrier 130 has at least one ball bearing 135 along the optical axis direction This may be provided.

The at least one ball bearing 135 is disposed between the lens carrier 130 and the housing 120 such that one surface of the lens carrier 130 and one surface of the housing 120 contact each other, and thus the lens carrier 130 through rolling motion ) While guiding the movement of the lens carrier 130 in the optical axis direction.

The upper case 110 may be combined with the housing 120 to form the appearance of the camera module. The upper case 110 may be combined with the housing 120 to surround a part of the outer surface of the housing 120. The upper case 110 may include a metal material or be made of a metal material to be grounded to a ground pad of a substrate mounted on the lower portion of the housing 120, and accordingly, to shield electromagnetic waves generated during driving of the camera module. have.

The magnetic body 160 may be disposed on one side of the lens carrier 130, and the coil 150 may be disposed on one surface of the substrate 140 mounted on the housing 120 to be spaced apart from the magnetic body 160. Can be. For example, the magnetic body 160 may be a magnet including a magnetic material having magnetic properties, or may be a conductor.

In each drawing of this document, unnecessary overlapping descriptions of elements having the same reference numerals and identical functions may be omitted, and details of possible differences are described in each drawing.

Further, the present invention can be applied to an OIS (Optical Image Stabilizer) or Zoom driver IC using VCM.

The basic principle of the present invention is as follows. For example, when an overlapping area is changed while maintaining a gap greater than or equal to a certain distance between a magnetic body 160 such as a magnet (or dielectric) and the coil 150 through which the alternating current (AC) flows, the coil is changed. The inductance of (150) itself changes. At this time, the position of the current lens may be tracked by sensing the size (see Equation 2 below) and the angle of the changing coil impedance (see Equation 1 below).

2 is an exemplary view of a voice coil motor (VCM) type actuator and a position control circuit according to an embodiment of the present invention.

Referring to FIG. 2, the actuator of the VCM method according to an embodiment of the present invention may include a coil 150, a driving circuit 200 and an impedance/digital conversion circuit 300.

In addition, the position control circuit of the VCM method according to an embodiment of the present invention, may include a driving circuit 200, an impedance / digital conversion circuit 300 and the control circuit 400.

The coil 150 may be spaced apart from the magnetic body 160 provided on one side of the lens carrier 130. For example, the coil 150 is formed on one surface of the substrate 140 (FIG. 1) mounted on the housing 120 (FIG. 1) and may be disposed to face the magnetic body 160, and the magnetic body 160 may be formed by electromagnetic force. The magnetic body 160 is spaced apart to provide a driving force. Accordingly, the coil 150 may transmit a driving force to the magnetic body 160, and an impedance/digital conversion circuit converts the voltage Vac for position detection including inductance information corresponding to the location information of the magnetic body 160. (300).

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

The driving circuit 200, based on the overlapping voltage (VDRV) input from the control circuit 400, the coil 150 includes a driving current (Idrv) and a current for detecting the position (idet) of the overlapping current (IDRV) ).

For example, the driving circuit 200 may provide a current for detecting the position to the coil 150. The position detecting current iide may include a specific frequency component Fmod. The specific frequency component (Fmod) is a frequency that can measure the amount of change in the impedance of the coil 150 without affecting the driving of the lens carrier 130, for example, may be a frequency higher than the audible frequency.

For example, the driving circuit 200 may provide a current for detecting the position to the coil 150 independently of the driving current Idrv. As another example, for more accurate and fast closed-loop position control, the driving circuit 200 applies the overlapping current (IDRV) in which the current for detecting the position (idet) and the driving current (Idrv) are superimposed on the coil 150. Can provide.

For example, the position detecting current (idet) is an alternating current including at least one specific frequency component (Fmod), for example, sinusoidal (sinusoidal wave) current, triangular wave (triangle wave) current, sawtooth wave (sawtooth wave) ) Current or square wave current.

In each embodiment of the present invention, the current for detecting the position (idet) is not limited to the current exemplified above, but may include any AC current including a specific frequency component.

For example, when the driving circuit 200 applies a driving current (Idrv) to the coil 150, an electromagnetic force is generated while current flows through the coil 150, and the driving force is provided to the magnetic body 160 by the electromagnetic force. Can be. For example, when the driving circuit 200 applies the driving current Idrv 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. Accordingly, a driving force for moving the lens carrier 130 in the direction of the optical axis or the direction perpendicular to the optical axis may be generated according to Fleming's left-hand rule. The lens carrier 130 may move in the optical axis direction or in a direction perpendicular to the optical axis by the driving force.

For example, the driving circuit 200 may include bridge circuits SH1 and SL1 and bridge driving circuits OP1, Rsen, and G.

For example, the bridge circuits SH1 and SL1 include a high-side transistor SH1 connected to one end of both ends of the coil 150 and a low-side transistor SL1 connected to the other end of both ends of the coil 150. ). Here, the bridge circuit is a circuit capable of supplying a driving current to the coil 150, and a half bridge or full bridge circuit may be applied, and is not limited to the circuit illustrated in this document.

The bridge driving circuits OP1, Rsen, and G coils the overlapping current IDRV in which the DC driving current Idrv and the AC position detecting current IDTV overlapping in response to the overlapping voltage VDRV. 150).

For example, the bridge driving circuits OP1, Rsen, and G include an operational amplifier OP1 that controls the low-side transistor SL1 so that the overlapping current flows through the low-side transistor SL1, and voltage detection. It may include a resistor (Rsen) for and a gain amplifier (G) for amplifying the detected voltage.

For example, the operational amplifier OP1 receives a superimposed voltage VDRV in which a DC driving voltage Vdrv and an AC position detecting voltage Vdet are superimposed, and a low-side transistor based on the superimposed voltage VDRV. By controlling (SL1), the overlapping current (IDRV=Idrv(DC)+idet(AC)) flows through the resistor Rsen and the low-side transistor SL1.

For example, the driving circuit 200 may include a driver IC (driver integrated circuit) that provides a driving current to the coil 150.

For example, the driving current (Idrv) may be a direct current (DC) current generated by the driving circuit 200 for driving the lens carrier 130, and the current for detecting the position (idet) is the lens carrier 130 ) Is generated by the driving circuit 200 for position detection, and as described above, may be an alternating current (AC) current having the specific frequency component Fmod.

The position detection voltage Vac may include the specific frequency component Fmod as an alternating voltage for position detection among voltages at both ends of the coil 150.

For example, the overlapping current IDRV may be expressed according to Equation 3 below.

In Equation 3, Idrv is a driving current (Idrv), idet is a current for position detection, and may be defined as k*cos(2*π*Fmod*t). And, k is the amplitude of the current for position detection.

The amplitude (k) and the frequency (Fmod) of the current (idet) for position detection may be a range capable of measuring the amount of change in the inductance of the coil 150 without affecting the driving of the lens carrier 130. For example, the amplitude (k) of the position detecting current (idet) is smaller than the magnitude of the direct current driving current so as not to affect the driving of the lens carrier 130, and the frequency (Fmod) of the position detecting current (idet) ) Should not affect the driving of the lens carrier 130, where it does not affect the driving is that the frequency should not cause the movement or resonance of the lens carrier.

For example, the amplitude k of the current for detecting the position (idet) is smaller than the magnitude of the driving current of the direct current, and the frequency (Fmod) of the current for detecting the position (idet) is higher than the audible frequency. For example, when the magnitude of the driving current is 100 mA, the amplitude k of the current for detecting the position may be 5 mA, and the frequency Fmod of the current for detecting the position may be 100 kHz.

For example, when using a driving current close to direct current (DC), in order to use the driving coil as a sensing combination, as shown in FIG. 3, an alternating current (AC) current is applied over the driving current that is direct current (DC). A mixing modulation technique is needed. Here, the amplitude and frequency of the alternating current (AC) current should be set under the following conditions. 1) It should be a range that does not affect the driving, and 2) it should be enough to derive a change in inductance as much as measurable.

In particular, since the amount of change of the inductance is small, a circuit for converting it is additionally required. In the present invention, a method of increasing its accuracy in the impedance/digital conversion circuit 300 that converts the change in the impedance size of the coil 150 to a position value To suggest.

On the other hand, the peak (Vac_peak) of the position detection voltage (Vac) including the impedance size change (inductance information) of the coil 150 may be expressed as in Equation 4 below.

In Equation 4, Vac_peak is a peak value of an AC voltage to be extracted from both ends of the coil 150, and is a peak value of a voltage for position detection including impedance size information. Iac_peak is the peak value of the alternating current including the impedance size information to be extracted.

In the sensorless structure of the present invention, by applying the current for detecting the position of the alternating current (AC) to the driving current of the direct current (DC), and applying it to the driving coil, the magnitude of the alternating voltage across both ends of the coil 150 is measured and the lens carrier The invention in which the position of the lens can be more accurately determined by measuring the amount of change in impedance according to the position change of will be described in more detail.

The effect of parasitic resistance component Rs of coil 150, which is unnecessary information from the size information of the impedance of the coil 150, in particular, this resistance component has a temperature-sensitive characteristic. Since it is possible to generate a large error in the total amount of change in impedance, we propose a technique to improve the accuracy in extracting the positional information of the lens due to the change in impedance (exactly the change in inductance) by removing the effect of temperature change caused by the resistance component. This technology is included in the impedance/digital conversion circuit 300.

The impedance/digital conversion circuit 300 converts an AC voltage (Vac) signal including a specific frequency component (Fmod) obtained at both ends of the coil 150 into a demodulation technique to generate the coil ( 150) to block (exclude) a high frequency signal having a resistance component, extract a low frequency signal having an inductance component of the coil 150 corresponding to the reactance component, and include location information based on the extracted low frequency signal The position signal SP can be detected.

Then, the control circuit 400 is based on the position signal SP containing the position information from the impedance/digital conversion circuit 300 and the control signal SC for control to a target position. 200) can be controlled.

For example, the control circuit 400 is based on the position signal SP including the position information and the control signal SC including the target position information, the driving driving voltage Vdrv and the positioning voltage The overlapping voltage VDRV including (Vac) may be provided to the driving circuit 200. For example, the control circuit 500 provides the overlapping signal SDRV for position control or position error control to the driving circuit 200 based on the position signal Sp and the control signal SC, The position of the magnetic body 160 can be precisely controlled. Here, the overlap signal SDRV may be the overlap voltage VDRV, and the overlap voltage VDRV is described in each embodiment of the present invention, but is not limited thereto.

As described above, the impedance/digital conversion circuit 300 uses the I/Q demodulation technique, and the local oscillation signal SLo having the same frequency and 90 degree phase difference as the specific frequency component Fmod (FIG. 4) ) From the demodulation signal (Sdmod, FIG. 4) generated by mixing the AC voltage (Vac) signal to exclude the low-frequency resistance component and extract only the reactance component.

Using such an I/Q demodulation technique, a resistance component can be excluded and a temperature change can be excluded based on a reactance component, so that an operation for detecting a more accurate position signal can be performed. The impedance/digital conversion circuit 300 will be described.

3 is an exemplary diagram of an impedance/digital conversion circuit according to an embodiment of the present invention.

Referring to FIG. 3, the impedance/digital conversion circuit 300 includes a first filter 311, a demodulator 321, a second filter 331, a voltage control oscillator 341, and a digital filter ( 351).

The first filter 311 may extract the AC voltage (Vac) signal from both ends of the coil 150. For example, the first filter 311 may be a high pass filter or a band pass filter, and may pass an alternating voltage (Vac) signal including a specific frequency component (Fmod) at both ends of the coil 150. have.

The demodulator 321 demodulates the AC voltage Vac signal extracted from the first filter 311 to induce the high frequency signal having the resistance component of the coil 150 and the inductance of the coil 150. A demodulation signal Sdmod including a low-frequency signal having a component may be provided. For example, the demodulator 321 may be an analog demodulator using a Gilbert cell, which is an analog block.

The second filter 331 may block the high frequency signal included in the demodulation signal Sdmod from the demodulator 321 and pass the low frequency signal to extract only the low frequency signal. Here, the low frequency signal passed by the second filter 331 is a signal having a reactance component of the impedance of the coil 150.

The voltage-controlled oscillator 341 may convert the low-frequency signal extracted from the second filter 331 into a frequency signal Sfreq based on its magnitude. For example, since the voltage control oscillator 341 can convert an analog signal to a digital signal, it can be replaced by an analog-to-digital converter (ADC) that performs the same function.

The digital filter 351 extracts the frequency component of the frequency signal Sfreq from the voltage control oscillator 341 and detects the location signal SP including location information based on the frequency component. It can be provided to the control circuit 500. Here, the position signal SP may be a position signal corresponding to the position of the magnetic body 160 or the position of the lens.

On the other hand, when describing the temperature compensation function in the present invention, in the equations 1 and 2, the parasitic resistance Rs of the coil 150 is a function of temperature, which is a formula of the primary function of the simplified temperature as follows. It can be expressed as Equation (5).

Depending on the magnitude of the driving current of the coil 150, a change in the temperature of the coil 150 may occur, which may affect the impedance value of the coil 150. If the portion occupied by the amount of change in the parasitic resistance compared to the amount of change by position among the portions of the amount of change according to the position of the total impedance, a problem that the accuracy of position prediction may be deteriorated may occur.

In order to solve this problem, the present invention proposes a method of removing or canceling the amount of change due to parasitic resistance, and this will be described.

In Equation 5, Rs is a parasitic resistance component of the coil 150, Rs0 is an intrinsic resistance component, TCR is a temperature coefficient of parasitic resistance, and Temp is an ambient temperature.

Among the voltages applied to both ends of the coil 150, the alternating voltage (Vac) can be expressed as Equation 6 below by changing the impedance of the coil into a magnitude (absolute value) and a phase angle.

On the other hand, the demodulator (Demodulator) 321, using the demodulation technique, the AC voltage from the first filter 311 (Vac, FIG. 4) signal, having the same frequency and 90 degree phase difference (or 270 degrees) The local oscillation signal SLo (FIG. 4) may be mixed to provide the demodulation signal Sdmod, and FIGS. 4, 5, and 6 will be described.

4 is an exemplary view of the demodulator of FIG. 3.

Referring to FIG. 4, the demodulator 321 may include a local oscillator 321-1 and a mixer 321-2.

The local oscillator 321-1 includes a frequency equal to a specific frequency component Fmod of the AC voltage Vac signal, and a local oscillation signal SLo having a phase difference of 90 degrees from the AC voltage Vac signal. It can be generated and provided to the mixer 321-2.

The mixer 321-2 may mix the AC voltage (Vac) signal and the local oscillation signal (SLo) to provide the demodulation signal (Sdmod).

5 is another exemplary view of the demodulator of FIG. 3.

5, the local oscillator 321-1, when the AC voltage (Vac) signal is'k*|ZL|*cos (ω*t+θ)', the local oscillation signal SLo As a result, a sine wave signal (sin(ω*t)) having a phase difference of 90 degrees from the AC voltage (Vac) signal may be generated.

Referring to FIG. 5, using the I/Q demodulation technique, the demodulator 321 is a local oscillation signal SLo, that is, a specific frequency of the AC voltage (Vac) signal of Equation (6). Sine wave signal (sin(ω*t)) (or -sin(ω*t)) having the same frequency as the component Fmod and a phase difference of 90 degrees (or 270 degrees), and alternating current from the first filter 311 The demodulation signal Sdmod represented by Equation 7 below may be provided by mixing with a voltage (Vac) signal, that is,'k*|ZL|*cos (ω*t+θ))'.

In Equation 7, if the demodulation signal Sdmod (k*|ZL|*cos (ω*t+θ)*sin(ω*t)) is summarized as a high-frequency component and a low-frequency component, You can organize it like the last formula.

Next, the demodulation signal (Sdmod) generated by the demodulator 321 (refer to Equation 7) is a reactance component (-k*) as shown in Equation 8 below among the impedance components through the second filter 331. A low frequency signal having ω*Lx/2) can be extracted. The low frequency signal having the reactance component (-k*ω*Lx/2) extracted here is input to the voltage control oscillator 341 and finally converted into a frequency signal (or digital signal) having a frequency component based on its magnitude. Can be.

In Equation 7, the demodulation signal Sdmod(k*|ZL|*cos (ω*t+θ)*sin(ω*t)) corresponds to the I component of the I/Q demodulation technique. Among the high frequency components and the low frequency components corresponding to the Q components, a low frequency component corresponding to the Q components may be extracted through the second filter 331.

As shown in Equation (8) by this extraction process, a low frequency signal having an inductance component (or reactance component) among impedance components of the coil 150 may be extracted, and the value obtained by Equation (8) may be extracted. A position signal SP based on an inductance component corresponding to an absolute value may be provided to the control circuit 500.

6 is another exemplary view of the demodulator of FIG. 3.

6, the local oscillator 321-1, when the AC voltage (Vac) signal is'k*|ZL|*cos (ω*t+θ)', the local oscillation signal SLo As a result, a cosine wave signal cos(ω*t) having a phase difference of 180 degrees from the AC voltage (Vac) signal may be generated.

6, the demodulator 321, as described above in Equations 7 and 8, is a local oscillation signal SLo, that is, a specific frequency component of the AC voltage Vac signal in Equation 6 above. Cosine signal (cos(ω*t)) (or -cos(ω*t)) having a frequency equal to (Fmod) and a phase difference of 360 degrees (or 180 degrees), and an alternating voltage from the first filter 311 The (Vac) signal, that is,'k*|ZL|*cos (ω*t+θ))', can be mixed to provide the demodulation signal Sdmod represented by Equation (9).

In Equation 9, if the demodulation signal Sdmod (k*|ZL|*cos (ω*t+θ)*cos(ω*t)) is arranged as a high-frequency component and a low-frequency component, the end of Equation 9 It can be arranged as a formula.

Next, the demodulation signal Sdmod (see Equation 9 above) generated by the demodulator 321 is a resistance component (k*Rs/) as shown in Equation 10 below among the impedance components through the second filter 331. A low frequency signal having 2) can be extracted. The extracted low-frequency component may be input to the voltage control oscillator 341 and finally converted into a frequency signal (or digital signal) having a frequency component based on its magnitude.

In Equation 9, the demodulation signal Sdmod ((k*|ZL|*cos (ω*t+θ)*cos(ω*t))) corresponds to the I component of the I/Q demodulation technique Among the high frequency components and the low frequency components corresponding to the Q components, the Q components may be extracted through the second filter 331.

Through this extraction process, as shown in Equation 10, a resistance component can be extracted from the impedance component of the coil, and a signal based on the resistance component corresponding to the absolute value of the value obtained through Equation 10 is It may be provided to the control circuit 500.

On the other hand, since the parasitic resistance component has a constant temperature coefficient of the coil material, the temperature of the coil can be predicted by converting this signal to digital. Although the temperature coefficient of inductance is not described in the above equation, it actually exists and has a small effect compared to the temperature coefficient of parasitic resistance, but it can be negligibly large compared to the total amount of change of inductance according to the overall position. Therefore, if the compensation is performed using the temperature of the coil measured here, the accuracy of the position of the lens can be further increased.

In addition, the ratio (sin/cos) of the absolute values of Equation 8 and Equation 10 may be obtained by obtaining a phase angle as a resistance (tan) and a ratio of resistance and inductance (*Lx/Rs).

On the other hand, the control circuit 500 of the position detection circuit according to an embodiment of the present invention, a processor (for example, a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, an application specific integrated circuit (Application Specific Integrated Circuit) , ASIC), Field Programmable Gate Arrays (FPGA), etc., memory (e.g. volatile memory (e.g. RAM, etc.), non-volatile memory (e.g. ROM, flash memory, etc.), input devices (e.g. keyboard , Mouse, pen, voice input device, touch input device, infrared camera, video input device, etc., output device (e.g. display, speaker, printer, etc.) and communication connection devices (e.g. modem, network interface card (NIC), Integrated network interface, radio frequency transmitter/receiver, infrared port, USB interface, etc. are interconnected with each other (e.g. peripheral component interconnect (PCI), USB, firmware (IEEE 1394), optical bus structure, network, etc.) It can be implemented as a computing environment.

The computing environment may be a personal computer, server computer, handheld or laptop device, mobile device (mobile phone, PDA, media player, etc.), multiprocessor system, consumer electronics, mini computer, mainframe computer, any of the aforementioned systems, or It may be implemented as a distributed computing environment including a device, but is not limited thereto.

In the above, the present invention has been described by way of example, but the present invention is not limited to the above-described embodiments, and those skilled in the art to which the invention pertains without departing from the gist of the invention claimed in the claims. Anyone can make various modifications.

100: camera module
130; Lens barrel
150: coil
160: magnetic material
200: driving circuit
300: impedance/digital conversion circuit
311: first filter
321: Demodulator
331 second filter
341: voltage control oscillator
351: digital filter
500: control circuit

Claims (12)

A coil spaced apart from the magnetic body provided on one side of the lens carrier;
A driving circuit for applying an overlapping current including a driving current and a position detecting current to the coil based on the input overlapping voltage; And
Impedance/digital that extracts a low-frequency signal having an inductance component of the coil by converting an AC voltage signal including a specific frequency component obtained at both ends of the coil to a demodulation technique, and detects a position signal based on the low-frequency signal Conversion circuit;
Actuator of the VCM method comprising a.
According to claim 1, The impedance / digital conversion circuit,
The high frequency signal having the resistance component of the coil converted by the demodulation technique is removed to compensate for temperature fluctuation caused by the resistance component.
VCM type actuator.
According to claim 1, The impedance / digital conversion circuit,
A first filter for extracting the AC voltage signal from both ends of the coil;
A demodulator demodulating the AC voltage signal extracted from the first filter to provide a demodulation signal including a high frequency signal having a resistance component of the coil and a low frequency signal having an inductance component of the coil;
A second filter for blocking the high frequency signal included in the demodulation signal and extracting the low frequency signal;
A voltage control oscillator for converting the low frequency signal extracted from the second filter into a frequency signal based on its magnitude; And
A digital filter that extracts a frequency component of the frequency signal and detects the location signal including location information based on the frequency component;
Actuator of the VCM method comprising a.
The method of claim 3, wherein the demodulator,
A local oscillator including a frequency equal to a specific frequency component of the AC voltage signal and generating a local oscillation signal having a phase difference of 90 degrees from the AC voltage signal; And
A mixer that mixes the AC voltage signal and the local oscillation signal to provide the demodulation signal;
Actuator of the VCM method comprising a.
According to claim 4, The local oscillator,
When the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', a sine wave signal'sin(ω*t)' having a 90 degree phase difference from the AC voltage signal is used as the local oscillation signal. Produced
VCM type actuator.
According to claim 4, The local oscillator,
When the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', the local oscillation signal is a cosine wave signal'cos(ω*t)' having a 180 degree phase difference from the AC voltage signal. To generate
VCM type actuator.
A driving circuit for applying an overlapping current including a driving current and a current for position detection based on the input overlapping voltage to a coil spaced apart from the magnetic body provided on one side of the lens carrier;
The AC voltage signal including a specific frequency component obtained at both ends of the coil is converted to a demodulation technique to block a high frequency signal having a resistance component of the coil, extract a low frequency signal having an inductance component of the coil, , An impedance/digital conversion circuit that compensates for temperature fluctuations caused by parasitic resistance of the coil and detects a position signal based on the extracted low frequency signal; And
A control circuit for controlling the driving circuit based on a position signal including position information from the impedance/digital conversion circuit and a control signal for control to a target position;
Position control device of the VCM method comprising a.
The control circuit according to claim 7,
Providing the superimposed voltage including the driving voltage for driving and the voltage for positioning based on the position signal and the control signal to the driving circuit
VCM type position control device.
The impedance/digital conversion circuit of claim 7,
A first filter for extracting the AC voltage signal from both ends of the coil;
A demodulator demodulating the AC voltage signal extracted from the first filter to provide a demodulation signal including a high frequency signal having a resistance component of the coil and a low frequency signal having an inductance component of the coil;
A second filter for blocking the high frequency signal included in the demodulation signal and extracting the low frequency signal;
A voltage control oscillator for converting the low frequency signal extracted from the second filter into a frequency signal based on its magnitude; And
A digital filter that extracts a frequency component of the frequency signal and detects the location signal including location information based on the frequency component;
Position control device of the VCM method comprising a.
The method of claim 9, wherein the demodulator,
A local oscillator including a frequency equal to a specific frequency component of the AC voltage signal and generating a local oscillation signal having a phase difference of 90 degrees from the AC voltage signal; And
A mixer that mixes the AC voltage signal and the local oscillation signal to provide the demodulation signal;
Position control device of the VCM method comprising a.
11. The method of claim 10, The local oscillator,
When the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', a sine wave signal'sin(ω*t)' having a 90 degree phase difference from the AC voltage signal is used as the local oscillation signal. Produced
VCM type position control device.
11. The method of claim 10, The local oscillator,
When the AC voltage signal is'k*|ZL|*cos (ω*t+θ)', the local oscillation signal is a cosine wave signal'cos(ω*t)' having a 180 degree phase difference from the AC voltage signal. To generate
VCM type position control device.

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