KR102516770B1 - Apparatus for controlling position of vcm using voltage/frequency conversion techniques - Google Patents

Abstract

An apparatus for controlling the position of a VCM according to an embodiment of the present invention includes a coil disposed opposite to a magnetic body provided on one side of a lens carrier; a driving circuit for applying an overlapping current including a driving current and a position detection current to the coil; a filter circuit for extracting a first AC voltage from the voltage at both ends of the coil; a voltage/frequency conversion circuit for converting the first AC voltage extracted from the filter circuit into a first frequency signal; and a digital control circuit for detecting location information based on the frequency component of the first frequency signal. includes

Description

VCM position control device using voltage/frequency conversion technique

The present invention relates to a VCM position control device using a voltage/frequency conversion technique.

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

As an existing technology, a method of performing position control using a Hall sensor and a magnet for position sensing 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 position of the Hall sensor may change depending on temperature or other external factors. For this, additional circuitry such as a low pass filter, auto gain control amplifier, differential to single amplifier or analog to digital converter is required. There is a downside to being

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 downsides to that.

In this way, in order to solve problems such as mechanical design restrictions of the camera module, additional current consumption, and material cost increase, a technology capable of more accurate position detection without employing a Hall sensor is required.

Republic of Korea Patent Publication No. 2013-0077216

An object of the present invention is to use a voltage/frequency conversion technique capable of improving noise exclusion characteristics in a system using a single driving coil for both detection and detection without using a separate sensing means such as a Hall sensor or a sensing coil. It is to provide a VCM position control device.

According to one embodiment of the present invention, the coil disposed opposite to 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 detection current to the coil; a filter circuit for extracting a first AC voltage from the voltage at both ends of the coil; a voltage/frequency conversion circuit for converting the first AC voltage extracted from the filter circuit into a first frequency signal; and a digital control circuit for detecting location information based on the frequency component of the first frequency signal. An apparatus for controlling the position of a VCM including a is proposed.

The current for position detection may include a specific frequency component, and the specific frequency component may be a frequency component capable of measuring a change in impedance of the coil without affecting driving of the lens carrier.

The position detection current may have one of a sinusoidal wave, a triangle wave, a sawtooth wave, and a square wave.

The voltage/frequency conversion circuit may be a voltage controlled oscillator that generates a first frequency signal having a frequency based on the magnitude of the first AC voltage extracted from the filter circuit.

The digital control circuit may be configured to perform position control or position correction control through the driving circuit based on the position information.

According to one embodiment of the present invention, the coil disposed opposite to 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 detection current to the coil; a filter circuit for extracting a first AC voltage from the voltage between the center tap of the coil and one end of the coil, and extracting a second AC voltage from the voltage between the center tap of the coil and the other end of the coil; a voltage/frequency conversion circuit for converting the first and second AC voltages extracted from the filter circuit into first frequency signals and second frequency signals; and a digital control circuit for detecting location information based on frequency components of the first frequency signal and the second frequency signal. An apparatus for controlling the position of a VCM including a is proposed.

The current for position detection may include a specific frequency component, and the specific frequency component may be a frequency component capable of measuring a change in impedance of the coil without affecting driving of the lens carrier.

The position detection current may have one of a sinusoidal wave, a triangle wave, a sawtooth wave, and a square wave.

The coil includes a first coil between the middle tap and one end and a second coil between the middle tap and the other end, and the first coil is configured to perform the first coil based on a change in impedance due to a position change of the magnetic body. 1 AC voltage may be provided, and the second coil may provide the second AC voltage based on impedance that does not change even when the position of the magnetic body changes.

The digital control circuit may perform a subtraction operation or division operation on the first frequency signal and the second frequency signal to remove noise and signal change due to temperature change.

The coil includes a first coil between the middle tab and one end, and a second coil between the middle tab and the other end, and the second coil is positioned between the magnetic body and the magnetic body by a shielding member. It can be made to have an impedance with which the influence of the change is blocked.

The voltage/frequency conversion circuit may be a voltage controlled oscillator that generates a first frequency signal and a second frequency signal having frequencies based on the respective magnitudes of the first AC voltage and the second AC voltage extracted from the filter circuit.

The digital control circuit performs predetermined signal processing using the first frequency signal and the second frequency signal to calculate noise included in the first frequency signal and the second frequency signal before calculating the location information. can be made to remove.

The digital control circuit may be configured to perform position control or position correction control through the driving circuit based on the position information.

The first inductance between the middle tap of the coil and one end of the coil may be set greater than the second inductance between the middle tap of the coil and the other end of the coil.

According to an embodiment of the present invention, since it does not include a separate sensing means such as a hall sensor, power consumption can be reduced, manufacturing costs can be reduced, and there are advantages in miniaturization, and thus the auto focus module. (Auto focus Module) or OIS module's competitiveness can be secured.

In addition, since defective elements and process processes that can occur during manufacturing are simplified, additional effects besides direct effects can be achieved, and since it has a sensor-less structure, it can be applied not only to auto focus (AF) actuators but also to OIS (Optical Image Stabilizer) actuators. there is.

In addition, since the ADC may not be used by using the voltage/frequency conversion function, problems associated with using expensive and large-sized high-performance ADCs may be improved.

That is, it is possible to improve noise exclusion characteristics and to perform more precise detection and control of the position of the lens by adding a temperature change compensation function.

1 is an exploded perspective view of a camera module according to an embodiment of the present invention.
2 is an exemplary block diagram of an apparatus for controlling a location of a VCM according to an embodiment of the present invention.
3 is another block diagram of an apparatus for controlling a location of a VCM according to an embodiment of the present invention.
4 is a first exemplary diagram of a voltage/frequency conversion circuit according to an embodiment of the present invention.
5 is a second exemplary diagram of a voltage/frequency conversion circuit according to an embodiment of the present invention.
6 is an exemplary view of a shielding member according to an embodiment of the present invention.
7 is a waveform diagram of main voltage and frequency signals according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detailed description of the present invention which follows refers to the accompanying drawings which illustrate, by way of example, specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable any person skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention in relation to one embodiment. Additionally, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the detailed description set forth below is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all equivalents as claimed by those claims. Like reference numbers in the drawings indicate the same or similar function throughout the various aspects.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice 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 10 according to an embodiment of the present invention includes a case 11, a housing 12, a lens carrier 13, a substrate 101, a coil 100, and a magnetic body 16. ) may be included. Also, the camera module 10 may include a ball bearing 13-B.

In addition, as shown in FIGS. 2 and 3 , the camera module may include a driving circuit 150, a filter circuit 200, a voltage/frequency conversion circuit 300, and a digital control circuit 400. .

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 13 may have a hollow shape so that at least one lens for capturing an image of a subject may be accommodated therein, and a lens may be provided inside the lens carrier 13 along an optical axis. Here, the optical axis direction refers to the Z-axis direction based on the lens carrier 13 shown in FIG. 1 .

The lens carrier 13 is disposed inside the housing 12 and is coupled with the housing 12, so that it can move in the optical axis direction for auto focusing and in a direction perpendicular to the optical axis for OIS (Optical Image Stabilizer) (FIG. 1 of X-axis direction or Y-axis direction). For example, the lens carrier may be a lens module including a lens barrel in which a lens is embedded.

The housing 12 includes an inner space, and the lens carrier 13 may be accommodated in the inner space of the housing 12 so that the lens carrier 13 is movable in an optical axis direction or a direction perpendicular to the optical axis.

As a guide means for guiding the movement of the lens carrier 13 when the lens carrier 13 moves in the optical axis direction within the housing 12, the lens carrier 13 includes at least one ball bearing 13- B) may be provided.

At least one ball bearing 13-B is disposed between the lens carrier 13 and the housing 12 so that one surface of the lens carrier 13 and one surface of the housing 12 come into contact with the lens carrier 13 through a rolling motion. While supporting (13), it is possible to guide the movement of the lens carrier 13 in the optical axis direction.

The case 11 may be combined with the housing 12 to form the exterior of the camera module. The case 11 may be coupled to the housing 12 so as to surround a portion of the outer surface of the housing 12 . The case 11 may include a metal material or be made of a metal material and be grounded to a ground pad of a board mounted on a lower portion of the housing 12, and thus, electromagnetic waves generated during driving of the camera module may be shielded. .

The magnetic body 16 may be disposed on one side of the lens carrier 13, and the coil 100 may be disposed on one side of the substrate 101 mounted on the housing 12 to face the magnetic body 16. For example, the magnetic material 16 may be a magnet including a magnetic material having a magnetic property, or may be a conductor or a dielectric material.

For example, the position control device of the VCM further includes a yoke (not shown) mounted on the other surface of the substrate 140 to improve the detection performance of the coil, so that the magnetic body 160 and the coil 150 Leakage of magnetic flux can be prevented.

In each drawing of this document, unnecessary redundant descriptions of components having the same reference numeral and same function may be omitted, and possible differences are described in each drawing.

2 is an exemplary block diagram of an apparatus for controlling a location of a VCM according to an embodiment of the present invention.

Referring to FIG. 2, the VCM position control device according to an embodiment of the present invention includes a coil 100, a driving circuit 150, a filter circuit 200, a voltage/frequency conversion circuit 300, and a digital control circuit. (400).

As described above, the coil 100 may be disposed to face the magnetic body 16 provided on one side of the lens carrier 13 .

The driving circuit 150 may apply an overlapping current IDRV including a driving current Idrv and a position detection current idet to the coil 100 based on the control voltage VREF. Accordingly, the overlapping current IDRV including the driving current Idrv and the current idet for position detection may flow through the coil 100, and the coil 100 may generate electromagnetic force by the current Idrv. The driving force by the can be transmitted to the magnetic body (16). Accordingly, the magnetic material 16 may be driven in the direction of the optical axis or in the direction perpendicular to the optical axis by the driving force of the coil 100 .

For example, a DC voltage by the driving current Idrv and a first AC voltage Vac1 by the current idet for position detection may be generated at both ends of the coil 100 . Accordingly, the filter circuit 200 may provide a first AC voltage V1 corresponding to the first AC voltage Vac1.

The filter circuit 200 may extract the first AC voltage V1 from the voltage of both ends of the coil 100 .

The voltage/frequency conversion circuit 300 may generate a first frequency signal F1 having a frequency based on the magnitude of the first AC voltage V1 extracted from the filter circuit 200.

Also, the digital control circuit 400 may detect location information based on the frequency component of the first frequency signal F1.

According to the foregoing, by the voltage / frequency conversion circuit 300, there is an advantage that an analog / digital converter (ADC) is unnecessary, and the digital control circuit 400, from the voltage / frequency conversion circuit 300 Noise may be removed by performing predetermined signal processing such as averaging using the first frequency signal F1 of .

3 is another block diagram of an apparatus for controlling a location of a VCM according to an embodiment of the present invention.

Referring to FIG. 3, the VCM position control device according to an embodiment of the present invention includes a coil 100, a driving circuit 150, a filter circuit 200, a voltage/frequency conversion circuit 300, and a digital control circuit. (400).

The coil 100 may be disposed opposite to the magnetic body 16 provided on one side of the lens carrier 13 .

As mentioned in the description of FIG. 2 , the driving circuit 150 may apply an overlapping current IDRV including a driving current Idrv and a position detection current idet to the coil 100 . .

Accordingly, the middle tap is connected between one end and the other end of the coil 100, so that a first AC voltage can be generated between one end and the middle tap of the coil 100, and the middle tap of the coil 100 A second AC voltage may be generated between the and the other end.

The filter circuit 200 extracts a first AC voltage V1 from the voltage Vac1 between the middle tap MT of the coil 100 and one end of the coil 100, and The second AC voltage V2 may be extracted from the voltage Vac2 between the middle tap MT of and the other end of the coil 100.

The filter circuit 200 generates a first AC voltage V1 at a voltage Vac1 between the middle tap MT and one end of the coil 100, among both ends and the middle tap MT of the coil 100. is extracted and provided to the voltage/frequency conversion circuit 300, and the second AC voltage V2 is extracted from the voltage Vac2 between the middle tap MT and the other end of the coil 100 to the voltage/frequency conversion circuit. (300).

The voltage/frequency conversion circuit 300 generates a first frequency signal F1 having a frequency based on the respective magnitudes of the first AC voltage V1 and the second AC voltage V2 extracted from the filter circuit 200. And a second frequency signal (F2) can be generated and provided to the digital control circuit (400).

The digital control circuit 400 may detect location information based on each frequency component of the first frequency signal F1 and the second frequency signal F2.

According to the foregoing, by the voltage / frequency conversion circuit 300, there is an advantage that an analog / digital converter (ADC) is unnecessary, and the digital control circuit 400, from the voltage / frequency conversion circuit 300 By performing predetermined signal processing such as subtraction or division using the first and second frequency signals F1 and F2 of , it is possible to remove the effect of noise or temperature change.

In addition, while the actuator of the camera module 10 is driven by the digital control circuit 400 and the driving circuit 150, as described above, the coil 100 has DC drive current Idrv and AC An overlap current IDRV in which the current idet for detecting the position of is overlapped may flow.

Also, the digital control circuit 400 may perform position control or position correction control through the driving circuit 150 based on the position information.

Meanwhile, one coil 100 shown in FIG. 2 may be equivalently modeled with an inductance component (Lx) and a resistance component (Rs).

In addition, among the coils 100 shown in FIG. 3, the first coil 110 from the middle tap MT to one side is equivalently modeled with a first inductance component Lx1 and a first resistance component Rs1. It can be. The second coil 120 from the middle tap MT to the other side of the coil 100 may be modeled with a second inductance component Lx2 and a second resistance component Rs2.

Here, the middle tap MT may be an arbitrary point between both ends of the coil 100, and for example, the coil 100 includes the first coil 110 between the middle tap MT and one end. ), and a second coil 120 between the middle tap MT and the other end.

The second coil 120 may include an impedance that is blocked from being affected by a positional change of the magnetic body 16 by a shielding member between the second coil 120 and the magnetic body 16 .

For example, the first inductance Lx1 between the middle tap MT of the coil 100 and one end of the coil 100 is between the middle tap MT of the coil 100 and the coil 100. It may be set larger than the second inductance Lx2 between the other ends.

For example, the first coil 110 may provide the first AC voltage V1 based on a change in impedance due to a change in position of the magnetic body 16, and the second coil 120, The second AC voltage V1 may be provided based on impedance that does not change even when the position of the magnetic body 16 changes.

For example, the DC driving current Idrv for driving the lens carrier 13 to which the magnetic material 16 is attached to the coil 100 and the AC position detection current for detecting the position of the lens carrier 13 (idet) is blurred, and accordingly, superimposed voltages appear at both ends of the coil 100 where the DC voltage due to the DC driving current (Idrv) and the AC voltage caused by the AC position detection current (idet) are superimposed. can

Meanwhile, referring to FIGS. 1, 2, and 3 , the driving circuit 150 may include bridge circuits MH and ML and bridge driving circuits A11 and R11.

For example, the bridge circuits MH and ML include a high-side transistor MH connected to one end of both ends of the coil 100 and a low-side transistor ML connected to the other end of both ends of the coil 100. ) may be included. Here, the bridge circuit is a circuit capable of supplying driving current to the coil, and a half-bridge or full-bridge circuit may be applied, and is not limited to the circuit exemplified in this document.

The bridge driving circuits A11 and R11 generate an overlapping current IDRV in which a DC driving current Idrv and an AC position detection current IDRV are superimposed in response to a control voltage VREF, and the coil 100 can supply to

For example, the bridge driving circuits A11 and R11 may include an operational amplifier A11 and a resistor R11 controlling the low-side transistor ML so that the overlapping current flows through the low-side transistor ML. can include

For example, the operational amplifier A11 receives a control voltage VREF in which a DC control voltage and an AC position detection voltage are superimposed, and controls the low-side transistor ML based on the control voltage VREF, The overlapping current (IDRV=Idrv(DC)+idet(AC)) flows through the resistor R11 and the low-side transistor ML.

For example, the position detection current idet may include a specific frequency component Fmod, and the specific frequency component Fmod does not affect driving of the lens carrier 13 and the coil ( 100) is a frequency component capable of measuring a change in impedance, and for example, it may be a frequency higher than an audible frequency (eg, 100 kHz).

For example, the position detection current (idet) may have one of a sinusoidal wave, a triangle wave, a sawtooth wave, and a square wave.

In each embodiment of the present invention, the AC position detection current is not limited to the signals exemplified above, and may include any AC signal including a specific frequency component.

For example, the overlap current IDRV may be expressed according to Equation 1 below.

In Equation 1, Idrv is a DC current corresponding to the drive current, and idet is a position detection current of the AC for position detection, which may be defined as k*sin(2*π*Fmod*t). And, k is the amplitude of the AC position detection current.

For example, when DC driving current Idrv flows through the coil 100 by the operational amplifier A11, electromagnetic force is generated as the DC driving current Idrv flows through the coil 100, and this electromagnetic force Driving force may be provided to the magnetic material 16 by the. That is, the driving circuit 150 may provide driving force to the magnetic material 16 by applying the driving current Idrv to the coil 100 . For example, when the driving circuit 150 applies a driving current (Idrv) of DC to the coil 100, a magnetic field is generated in the coil 100, and the magnetic field generated in the coil 100 is equal to the magnetic field of the magnetic body 16. By interaction, a driving force for moving the lens carrier 13 in the optical axis direction (or in the direction perpendicular to the optical axis) can be generated according to Fleming's left hand rule.

Accordingly, the lens carrier 13 may move in the direction of the optical axis or in a direction perpendicular to the optical axis by the driving force. For example, the driving circuit 150 may include a Driver Integrated Circuit (IC) that provides DC driving current Idrv to the magnetic material 16 .

In addition, the current idet for detecting the position of the AC of the overlapping current IDRV is generated by the operational amplifier A11 for detecting the position of the lens carrier 13, and as mentioned above, the position of the AC The current for detection (idet) is a current having a specific frequency component (Fmod).

On the other hand, in the present invention, in a state where a certain or more gap is maintained between the magnetic body 16 (FIG. 1) and the coil 100, the magnetic body 16 and the coil 100 according to the positional change of the magnetic body 16 An overlapping area between the ends is changed, and a change in inductance value of the coil may occur according to the change in the overlapping area.

At this time, the current position of the lens carrier 13 (or lens) may be tracked by sensing the magnitude |ZL| of the impedance of the coil 100 that changes. In order to use the coil 100 for both driving and sensing, a modulation technique is used in which the DC driving current Idrv is mixed with the AC current for position detection (idet).

At this time, the impedance magnitude (|ZL|) can be expressed according to Equation 2 below.

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

Referring to Equation 2, it can be seen that when the magnitude of the impedance of the coil 100 changes, the voltage across the coil 100 changes. Accordingly, the magnitude of the impedance can be detected by measuring the voltage across the coil 100. there is.

In addition, the magnitude of the impedance of the coil 100 (|ZL|) can be expressed according to Equation 3 below.

In Equation 3, Rs corresponds to a resistance component of the coil 100, Lx is an inductance component of the coil 100, and Fmod is a specific frequency component, and Fmod may be higher than an audible frequency.

The magnitude (k) and frequency (Fmod) of the current for detecting the position of the AC may be within a range capable of measuring a change in inductance of the coil 100 without affecting driving of the lens carrier 13 . For example, the magnitude (k) of the current for detecting the position of AC is small compared to the magnitude of the driving signal to the extent that it does not affect the driving of the lens carrier 13, and the frequency (Fmod) of the current for detecting the position of AC is the lens carrier 13. It should not affect the driving of (13). Here, not affecting the driving means that it should be a frequency that does not cause movement or resonance of the lens carrier.

For example, the magnitude (k) of the position detection current of AC is smaller than the magnitude of the drive signal, and the frequency (Fmod) of the AC position detection current is higher than the audible frequency. For example, when the magnitude of the driving current is 100 mA, the magnitude (k) of the AC position detection current may be 5 mA, and the frequency (Fmod) of the AC position detection current may be 100 kHz.

In particular, in each embodiment of the present invention, the above-described voltage/frequency conversion technique is employed so as to be able to detect even when the change in inductance is small. This will be described later.

2 and 3 show an example of a circuit capable of measuring a change in the magnitude of impedance according to a change in the position of a lens in a linear drive of a voice coil motor (VCM) using a voltage/frequency conversion technique.

2 and 3, the inductance value of the coil 100 changes according to the change in the position of the lens carrier, and an overlapping current (IDRV=Idrv(DC)+idet(AC)) flows through the coil 100. Among the superimposed voltages appearing across the coil in the situation, the alternating voltage changes according to the change in impedance. The AC voltage may be extracted from the filter circuit 200.

For example, the digital control circuit 400 performs predetermined signal processing using the first frequency signal F1 and the second frequency signal F2, and before calculating the location information, the Noise included in the first frequency signal F1 and the second frequency signal F2 may be removed. For example, the predetermined signal processing by the digital control circuit 400 may be a subtraction operation or a division operation for the first frequency signal F1 and the second frequency signal F2. Through this, noise and signal change due to temperature change can be removed. Accordingly, the digital control circuit 400 can compensate for changes due to noise and temperature.

As described above, FIG. 3 shows a structure in which one coil 100 acts as two coils 110 and 120 by using the middle tap MT.

In FIG. 3, by connecting a signal line at a middle tap (MT) (tap) in one coil 100, two first and second AC voltages (Vac1, Vac2) in one coil are physically generated in the filter circuit (200). ) can be entered. In this case, the filter circuit 200 may include a structure capable of extracting the first and second AC voltages V1 and V2.

As such, there is an effect of using the two coils 110 and 120 as one coil 100, which positions the second coil 120 among the first and second coils 110 and 120 with respect to the middle tap MT. It is possible to cancel the effect of noise and temperature change by eliminating the impedance change due to the change and processing the two signals F1 and F2 input from the first and second coils 110 and 120.

To explain this in detail, as described above, the impedance changes according to the change in the position of the lens and a method of sensing this is used. When the temperature changes, the impedance also changes. In this case, it is impossible to know whether the change in impedance is caused by a change in temperature or a change in position. In the case of products applied to mobile phones, it is necessary to compensate for temperature changes because the operation must be guaranteed from -20 to 80 degrees.

For example, when physically one coil 110 functionally includes two first and second coils 110 and 120 by a middle tap MT, the impedance of each of the first and second coils 110 and 120 When L1 and L2 are set, L1 is the impedance of the first coil 110 that varies according to the position. L2 is the impedance of the second coil 120 that does not change according to the position of the second coil 120 .

For example, if the subtraction operation (L1-L2) is performed, the part of the impedance change due to the temperature change can be offset, and only the impedance change according to the position can be obtained. In addition, since the noise component is commonly applied to the two coils 110 and 120, it can be canceled in the same way.

(1) Impedance L1 with change according to position

: L (basic inductance) + △L_t (temperature change) + noise + △L_p (position change)

(2) Impedance L2 with no change with position

: L (basic inductance) + △L_t (temperature change) + noise

4 is a first exemplary diagram of a voltage/frequency conversion circuit according to an embodiment of the present invention, and FIG. 5 is a second exemplary diagram of a voltage/frequency conversion circuit according to an embodiment of the present invention.

Referring to FIG. 4 , for example, the voltage/frequency conversion circuit 300 may include a sample/hold circuit 320 and a VCO circuit 330.

5, the voltage/frequency conversion circuit 300 may further include an amplifier circuit 310 for amplifying a small signal. For example, the amplifier circuit 310 may further include the sample/frequency converter 310. It may be disposed at the input terminal of the hold circuit 320, but is not limited thereto.

4 and 5, since the input AC voltage is very small, the amplification circuit 310 of the voltage/frequency conversion circuit 300 amplifies it and provides it to the sample/hold circuit 320, The circuit 320 samples and maintains the magnitude of impedance in the AC voltage according to a clock signal, and provides the sampled sample signal V1 to the voltage controlled oscillator (VCO) circuit 330. Thereafter, the VCO circuit 330 may convert the input sample signal V1 into a digital frequency signal F1 in a clock form.

Accordingly, based on the AC voltage extracted from the coil 100, a frequency value may be obtained by an impedance magnitude, and eventually, a voltage magnitude corresponding to the impedance magnitude may be converted into a frequency signal.

For example, the VCO circuit 330 may be a circuit capable of providing a signal having an oscillation frequency that varies according to a voltage level.

Accordingly, as the voltage/frequency conversion circuit is used, the ADC may not be used, and thus, problems associated with using expensive and large-sized high-performance ADCs may be improved. In other words, since high resolution (several uV) is required when configuring a circuit with ADC, a high-performance ADC is required, and it is difficult to implement it at a mass production level, and even if it is implemented, it is economically unfavorable because it uses a large area inside the IC. If this is replaced with a voltage/frequency conversion circuit and then digitally processed through a digital control circuit, it is more economical because it has improved mass productivity through a simpler circuit configuration and can be implemented in a relatively small size and area.

Next, the digital control circuit 400 may detect positional information based on frequency components in the frequency signals F1 or F1 and F2, which are digital signals from the voltage/frequency conversion circuit 300.

6 is an exemplary view of a shielding member according to an embodiment of the present invention.

Referring to FIG. 6 , in the second coil 120 of the coil 100, in order to prevent a change in impedance due to a change in position between the magnetic body and the coil, the second coil 120 is shielded between the magnetic body and the magnetic body. By the member, the influence of the positional change of the magnetic body 16 may include an impedance that is blocked.

For example, the shielding member for preventing the second coil 120 from changing impedance due to a change in position between the magnetic body and the coil, when the coil 100 is made of a multilayer coil, has a magnetic body 16 on one layer. A shielding member made of a material that does not react with may be disposed. As another example, the second coil 120 may be disposed so as not to directly overlap the magnetic body 16 . In addition, it may be implemented in other ways, and is not limited to the above-mentioned methods.

7 is a waveform diagram of main voltage and frequency signals according to an embodiment of the present invention.

In FIG. 7, Vac1 is an AC voltage generated by an AC current (idet) for position detection among overlapping voltages appearing at both ends of the coil 100, and VSH is the sample/hold circuit 320 of the voltage/frequency conversion circuit 300. ), SPL_CLK is a sample clock used in the sample/hold circuit 320, and F1 is a first frequency signal output from the VCO circuit 330 of the voltage/frequency conversion circuit 300.

In the above, the present invention has been described with specific details such as specific components and limited embodiments and drawings, but these are provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, Those skilled in the art to which the present invention pertains may seek various modifications and variations from these descriptions.

Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and not only the claims to be described later, but also all modifications equivalent or equivalent to these claims fall within the scope of the spirit of the present invention. will do it

10: camera module
11: case
12: housing
13: lens carrier
13-B: ball bearing
16: magnetic body
100: coil
101: substrate
200: filter circuit
300: voltage/frequency conversion circuit
400: digital control circuit

Claims (15)

A coil disposed opposite to 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 detection current to the coil;
a filter circuit for extracting a first AC voltage from the voltage at both ends of the coil;
a voltage/frequency conversion circuit for converting the first AC voltage extracted from the filter circuit into a first frequency signal; and
a digital control circuit for detecting positional information based on a frequency component of the first frequency signal;
VCM position control device including a.
The method of claim 1, wherein the position detection current
It may include a specific frequency component, wherein the specific frequency component is a frequency component capable of measuring a change in the impedance of the coil without affecting driving of the lens carrier.
The method of claim 1, wherein the position detection current
A device for controlling the position of a VCM having one of a form of a sinusoidal wave, a triangle wave, a sawtooth wave, and a square wave.
The method of claim 1, wherein the voltage / frequency conversion circuit,
A position control device of a VCM that is a voltage controlled oscillator that generates a first frequency signal having a frequency based on the magnitude of the first AC voltage extracted from the filter circuit.
The method of claim 1, wherein the digital control circuit
A position control device of a VCM that performs position control or position correction control through the drive circuit based on the position information.
A coil disposed opposite to 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 detection current to the coil;
a filter circuit for extracting a first AC voltage from the voltage between the center tap of the coil and one end of the coil, and extracting a second AC voltage from the voltage between the center tap of the coil and the other end of the coil;
a voltage/frequency conversion circuit for converting the first and second AC voltages extracted from the filter circuit into first frequency signals and second frequency signals; and
a digital control circuit for detecting positional information based on the frequency components of each of the first frequency signal and the second frequency signal;
VCM position control device including a.
The method of claim 6, wherein the position detection current
It may include a specific frequency component, the specific frequency component does not affect the driving of the lens carrier, the position control device of the VCM that is a frequency component capable of measuring the amount of change in the impedance of the coil.
The method of claim 6, wherein the position detection current
A device for controlling the position of a VCM having one of a form of a sinusoidal wave, a triangle wave, a sawtooth wave, and a square wave.
The method of claim 6, wherein the coil,
a first coil between the middle tap and one end, and a second coil between the middle tap and the other end;
The first coil provides the first AC voltage based on a change in impedance due to a change in position of the magnetic body;
The second coil provides the second AC voltage based on impedance that does not change even when the position of the magnetic body changes.
VCM position control device.
The method of claim 9, wherein the digital control circuit,
Performing a subtraction operation or a division operation on the first frequency signal and the second frequency signal to remove noise and signal change due to temperature change
VCM position control device.
The method of claim 6, wherein the coil,
a first coil between the middle tap and one end, and a second coil between the middle tap and the other end;
The second coil has an impedance in which the influence of the change in position of the magnetic body is blocked by a shielding member between the second coil and the magnetic body.
VCM position control device.
The method of claim 6, wherein the voltage / frequency conversion circuit,
Position control device of VCM, which is a voltage controlled oscillator that generates a first frequency signal and a second frequency signal having a frequency based on the respective magnitudes of the first AC voltage and the second AC voltage extracted from the filter circuit.
The method of claim 6, wherein the digital control circuit
The location of the VCM that performs predetermined signal processing using the first frequency signal and the second frequency signal to remove noise included in the first frequency signal and the second frequency signal before calculating the location information. controller.
The method of claim 6, wherein the digital control circuit
A position control device of a VCM that performs position control or position correction control through the drive circuit based on the position information.
The method of claim 6, wherein the first inductance between the middle tap of the coil and one end of the coil is
VCM position control device set to be greater than the second inductance between the middle tap of the coil and the other end of the coil.

Images