KR102052982B1 - Method for calibrating VCM driving device and the VCM driving device - Google Patents

Abstract

A VCM drive and a method for calibrating the VCM drive, wherein the calibration method, the VCM drive is calibrated from the host so that the lens that is automatically adjusted by the VCM can have a focus position according to the user's intention Receiving a command; correcting, by the VCM driving device, a bias voltage of the hall sensor; and correcting, by the VCM driving device, an output value of a sensor unit that detects and outputs a value relating to a position of a lens.

Description

Method for calibrating VCM driving device and the VCM driving device}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device, and more particularly, to a technique for correcting a state of a VCM driving device supplying a driving current to a voice coil motor (VCM) driving a lens.

Some of the optical lenses (hereinafter, simply lenses) mounted on the user device are automatically adjusted. The lens may be equipped with a voice coil motor (VCM) for auto focus adjustment. According to this configuration, when a current flows through the VCM, the focal length is adjusted while the lens moves in the optical axis direction. When the lens is in the 'macro position' on the optical axis, the focus is formed at the minimum focal length according to the lens design, and when the lens is in the 'infinity position' on the optical axis, the focal point may be formed at the farthest infinity distance.

The macro position and the infinity position are determined by the design specifications of the lens itself. According to the designer's design intent, the lens should remain at the infinity position when the VCM is provided with 'infinite corresponding current', and when the 'macro correspondence current' is provided to the VCM, the lens should remain at the macro position. However, unlike the design intention, there may be a process error in the VCM driving device providing current to the lens, the VCM, and the VCM, and an error may occur even when the lens, the VCM, and the VCM driving device are combined with each other. Due to this error, the lens may not remain in the infinity position even when the VCM is provided with the 'infinite correspondence current', and the lens does not stay in the macro position even when the VCM is provided with the 'macro response current'. May occur. Therefore, there is a need to provide a correction method for correcting the error immediately after coupling the lens, the VCM, and the VCM drive with each other.

In particular, when the lens position is controlled by a closed loop method of feedback type, successful feedback control can be performed by accurately measuring the current position of the lens, and the current position of the lens can be accurately measured by a process error. There is no problem.

In the technique of controlling the lens position in a feedback manner, the VCM driving apparatus may include a hall sensor configured to detect the position of the lens included in the imaging apparatus. However, the output voltage of the Hall sensor may be changed not only by the position of the lens but also by the bias voltage provided to the Hall sensor. In the initial design, the Hall sensor may be designed to provide a desirable initial bias voltage. However, the output voltage of the hall sensor may not accurately reflect the current position of the actual lens.

In the present invention, to provide a technique for calibrating the VCM drive so that the lens that is automatically adjusted by the VCM has a focus position that is suitable for the user's intention.

Specifically, a correction current is provided so that the user can actually move the lens to the infinity position when the user wants to move the lens to the infinity position, and the user wants to move the lens to the macro position. It is intended to provide a technique for calibrating a VCM drive to actually move the lens to the macro position.

In addition, to calibrate the VCM driver, it is to provide a method for calibrating the bias voltage provided to the Hall sensor included in the VCM driver.

According to an aspect of the invention, the sensor unit for outputting the pre-calibration position value 131 about the current position of the lens, the driving unit for outputting the current (I) provided to the VCM (Voice Coil Motor) for driving the lens ( 150) and a control unit 140 for controlling the operation of the drive unit based on the pre-calibration position value provides a VCM drive calibration method for calibrating the state of the VCM drive device. can do. In this case, the sensor unit includes a Hall sensor for outputting a voltage relating to the position of the lens, the VCM driving device, when the lens is placed in the macro position of the first value (MIN) is designed in advance Correcting the bias voltage provided to the hall sensor so as to output or output the second value MAX which is previously designed by the sensor unit when the lens is placed at an infinity position. The sensor unit outputs the first value MIN when the lens is placed at the macro position, and the sensor unit outputs the second value MAX when the lens is placed at the infinity position, It may include the step of calibrating the setting state of the control unit.

In this case, the host may further include receiving a user input requesting to calibrate the VCM driver through a user interface, and providing the calibration command to the VCM driver by the host.

The calibrating of the bias voltage may include: setting, by the VCM driver, the bias voltage of the hall sensor to an initial value VB_I, while the VCM driver maintains the lens at an infinite position. The VCM driver adjusts the bias voltage of the Hall sensor, and the VCM driver adjusts the bias voltage adjusted in the first adjustment step to output the second value MAX. Storing the 1 bias voltage value VB_INF, and setting the bias voltage of the hall sensor back to the initial value VB_I, wherein the VCM driving device maintains the lens at a macro position. In the second control step of adjusting the bias voltage of the Hall sensor, the VCM driving device, the VCM driving device, so that the sensor unit outputs the first value (MIN) in the state, Storing the bias voltage adjusted in the second adjusting step as a second bias voltage value VB_MAC, and the VCM driving apparatus stores the bias voltage of the hall sensor in the first value MIN and the second value. (MAC) may include calibrating to a lesser value.

The calibrating the setting state of the controller may include calculating a coefficient of the first equation using the pre-calibration position value as an independent variable.

According to an aspect of the present invention, a VCM driving device includes: a sensor unit configured to output a pre-calibration position value PU related to a current position of a lens, and including a hall sensor to output a voltage related to the position of the lens; The driving unit may output a current provided to the VCM driving the lens, and the controller may control an operation of the driving unit based on the pre-calibration position value. At this time, the control unit outputs the first value MIN which is previously designed when the lens is placed in the macro position, or when the lens is placed at the infinity position, the sensor unit is designed in advance. Correcting the bias voltage provided to the hall sensor to output a second value MAX, and when the lens is placed in the macro position, the sensor unit outputs the first value MIN, and the lens May be configured to calibrate the setting state of the control unit such that the sensor unit outputs the second value MAX when is set to an infinite position.

At this time, the control unit, in order to perform the step of correcting the bias voltage, setting the bias voltage of the Hall sensor to an initial value (VB_I), the state in which the VCM driving device maintains the lens in the infinity position In the first control step of adjusting the bias voltage of the Hall sensor, so that the sensor unit outputs the second value (MAX) in the first control step, and stores the bias voltage adjusted in the first adjustment step as a first bias voltage value (VB_INF) And setting the bias voltage of the hall sensor back to the initial value VB_I. The sensor unit outputs the first value MIN while the VCM driving device maintains the lens in the macro position. In order to control the bias voltage of the Hall sensor, the bias voltage adjusted in the second regulation step may be stored as a second bias voltage value VB_MAC. Phase, and it may be adapted to perform the step of correcting the bias voltage of the Hall sensor with the first value (MIN) and the second value (MAC) of the value that is larger.

The control unit may receive the pre-calibration position value PU and convert the converted position value PC into a calibrated position value PC, and output the correction unit 141. An error detector 142 for calculating a difference value and a driving current controller 143 for generating a control signal provided to the driver based on the difference value may be included.

An autofocus control system according to an aspect of the present invention includes a lens whose focal length is controlled by a VCM, and a VCM driving device providing a driving current of the VCM, wherein the VCM driving device includes a current position of the lens. A sensor unit configured to output a pre-correction position value PU relating to the sensor, the sensor unit including a hall sensor for outputting a voltage relating to the position of the lens, a driving unit for outputting a current provided to the VCM driving the lens, and the It may include a control unit for controlling the operation of the drive unit based on the position value before calibration. At this time, the control unit outputs the first value MIN which is previously designed when the lens is placed in the macro position, or when the lens is placed at the infinity position, the sensor unit is designed in advance. Correcting the bias voltage provided to the hall sensor to output a second value MAX, and when the lens is placed in the macro position, the sensor portion outputs the first value MIN, and The sensor may be configured to correct the setting state of the controller so that the sensor unit outputs the second value MAX when the lens is positioned at the infinity position.

According to the present invention, the VCM driving device can be calibrated so that a lens whose focus is automatically adjusted by the VCM can have a focusing position suitable for a user's intention. That is, it provides a correction current that allows the user to actually move the lens to the infinity position when the user wants to move the lens to the infinity position, and actually moves the lens when the user wants to move the lens to the macro position. It is possible to provide a calibration current to move to the macro position. In addition, in order to calibrate the VCM driver, the bias voltage provided to the Hall sensor included in the VCM driver may be calibrated.

1 illustrates an 'autofocus lens driving system' according to an exemplary embodiment.
Figure 2 shows the configuration of the 'autofocus lens driving system' according to an embodiment of the present invention.
Figure 3 shows the input and output flow of the PID control unit according to an embodiment of the present invention in detail.
4 is a flowchart of a process of calibrating a bias voltage of a hall sensor according to an embodiment of the present invention.
5 is a graph illustrating an ADC output value output from a sensor unit according to a position of a lens before the Hall sensor bias voltage is corrected according to an exemplary embodiment of the present invention.
FIG. 6A is a graph of a first case before calibration of the Hall sensor bias voltage according to an embodiment of the present invention, and FIG. 6B is a graph of a first case of correcting the Hall sensor bias voltage according to an embodiment of the present invention. 6C is a graph illustrating a second case before calibration of the Hall sensor bias voltage according to an embodiment of the present invention, and FIG. 6D is a graph in which the Hall sensor bias voltage is corrected according to an embodiment of the present invention. The graph of two cases is shown.

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described herein and may be implemented in various other forms. The terminology used herein is for the purpose of understanding the embodiments and is not intended to limit the scope of the invention. Also, the singular forms used below include the plural forms unless the phrases clearly indicate the opposite meanings.

1 illustrates an 'autofocus lens driving system' according to an exemplary embodiment.

The housing 21 includes a lens barrel 22 including a lens 220 and a magnet 23, a ball 24 for smoothly moving the lens 220, and a coil 240. It may include. The lens 220 is configured to automatically focus as the lens moves up and down.

When the lens is to be moved to the 'target position', the lens may be moved to the 'target position' using a method of feedback control of the VCM. In this case, for the feedback control, the hall sensor 110 may detect and output a 'current position value' regarding the current position of the lens 220. The VCM is feedback controlled until the detected 'current position value 131 (PU)' is equal to the 'target position'.

 The 'target position' may be defined on the y axis, which is the optical axis of the lens 220, and may have a value between the macro position (y = 0) and the infinity position (y = 1023). In this case, in order for the feedback control to be successful, when the lens 220 exists at the y = n position (n = 0, ..., 1023), the current position value 131 outputted by the hall sensor must correspond to the n. do. Hereinafter, for the convenience of description of the present specification, the position of the lens will be given an example having an integer value of 0 to 1023.

To this end, when the lens 220 is present at the y = n position (n = 0, ..., 1023), the value output from the hall sensor 110 is n and the current position value of the lens 220. It can be designed to be the same. However, despite this design, due to the process error of the VCM driving apparatus including the PIC controller, there is a problem that the value output from the hall sensor may deviate from n when the lens is in the y = n position.

2 and 3 are configuration diagrams for solving the above-described problems.

Figure 2 shows the configuration of the 'autofocus lens driving system' according to an embodiment of the present invention.

VCM driving apparatus 10 according to an embodiment of the present invention is a hall sensor (hall sensor) 110, an amplifier (Gain AMP) 120, ADC 130, PID control (PID control) 140, the driver The driver 150 may include a hall sensor bias voltage driver 160, a host clock input terminal 171, a host data input terminal 172, and a driving current output terminal 173.

The VCM driving apparatus 10 includes an imaging device including a lens 220, an image sensor 230 for receiving light incident through the lens 220, and a VCM 210 for adjusting a focal length of the lens 220. The operation of 20 can be controlled. In addition, the VCM driving apparatus 10 may detect the position of the lens 220 using the hall sensor 110.

The magnet 250 and the coil 240 may be installed in the imaging device 20. The magnet 250 may be fixed to the lens 220. When the driving current I is provided to the coil 240, the position of the lens 220 may be changed by an electromagnetic force formed between the magnet 250 and the coil 240.

The hall sensor 110 included in the VCM driving apparatus 10 may detect a magnetic force of the magnet 250 disposed in the lens 220 and output a voltage value VO regarding the position of the lens 220. The hall sensor 110 may be provided with a bias voltage VB for the operation of the hall sensor 110. The bias voltage VB may be provided by the hall sensor bias voltage driver 160. The bias voltage VB provided by the hall sensor bias voltage driver 160 may be controlled by the PID controller 140.

The hall sensor 110 may be designed to output a voltage value related to the position of the lens 220. For example, the Hall sensor 110 outputs a value of 0 when the lens 220 is in the macro position, and the ADC 130 outputs 1023 (= CODE_M) when the lens 220 is in the infinity position. It can be designed to output a voltage value VO to output a value. However, if a process error exists, it may not be possible to output the correct value.

The hall sensor 110, the amplifier 120, and the ADC 130 constitute the sensor unit 100.

The PID controller 140 may receive a command provided by the host 30 through the host clock input terminal 171 and the host data input terminal 172. The host 30 may provide a command for the focal length of the lens 220 to have a value suitable for a user's intention. Accordingly, the host 30 may receive a user input through the user interface 40.

The PID controller 140 may provide a digital value to the driver 150, and the driver 150 may provide a driving current I to the VCM 210 according to the digital value.

Figure 3 shows the input and output flow of the PID control unit according to an embodiment of the present invention in detail.

The PID controller 140 may include a corrector 141, an error detector 142, and a driving current controller 143. The correction unit 141 may receive the value 131 (PU) output from the sensor unit 100, correct it, and output the corrected value 132 (PC) to the error detector 142. The error detector 142 may determine the error value err by comparing the PC value with a value relating to a target position of the lens set by the user and a position target 133. The driving current controller 143 may receive the error value err and the PT value and output the driving current control value to the driving unit 150.

In order to solve the problem described above in FIG. 1, the present invention uses a calibration method described below.

<Process to Calibrate Bias Voltage of Hall Sensor>

4 is a flowchart of a process of calibrating a bias voltage of a hall sensor according to an embodiment of the present invention.

In step S10, the bias voltage VB of the hall sensor may be set to an initial value VB_I.

In this case, in the preferred embodiment, the initial value VB_I may satisfy the following condition. That is, the initial value VB_I is such that when the lens 220 is in the macro position, the output value of the 'sensor part 100' has a value larger than the preset MIN (ex: '0'), and the lens is positioned at the infinity position. When present, the output value of the 'sensor unit 100' may be set to a value that has a smaller value than a preset MAX (ex: '1023'). The output value of the sensor unit 100 is the output value of the ADC.

5 is a graph illustrating an ADC output value output from the sensor unit 100 according to the position of the lens before the Hall sensor bias voltage is corrected according to an exemplary embodiment of the present invention. That is, it may mean a graph when the Hall sensor bias voltage is set to the initial value VB_I. The horizontal axis of the graph represents the actual positions (MACRO to INFINITE) of the lens, and the vertical axis represents the output value PU of the ADC with respect to the position of the lens.

In operation S20, the lens 220 may be moved to an infinity position. Prior to calibrating the VCM drive 10, the position of the lens 220 may not be precisely controlled, but may be moved to an infinity position or a macro position. Then, the sensor unit 100 may output an E_INF (ex: '1000') smaller than the MAX.

In operation S30, the lens may be held at an infinite position, and at this time, the bias voltage VB_INF for causing the sensor 100 to output the MAX may be found and stored.

At this time, in one embodiment of the present invention, if the bias voltage is increased than VB_I, the sensor unit 100 may be designed to output a value larger than the E_INF when the lens is in an infinite position. have. Therefore, in the VCM driving apparatus 10 according to an embodiment of the present invention, a relationship in which VB_INF> VB_I is established.

In step S110, the bias voltage VB of the hall sensor may be set back to the initial value VB_I.

In operation S120, the lens may be moved to the macro position. Then, the sensor unit 100 may output an E_MAC (ex: '50') larger than the MIN.

In operation S130, the lens may be maintained to have the macro position, and at this time, the bias voltage VB_MAC for causing the sensor unit 100 to output the MIN may be found and stored. At this time, the relationship VB_MAC> VB_I is established.

In this case, in the present invention, when the bias voltage is increased than VB_I, the sensor unit 100 may be designed to output a smaller value than the E_MAC when the lens is in the macro position.

In step S200, the smaller of VB_MAC and VB_INF is determined as the final bias voltage VB_F, and in step 210, the bias voltage of the hall sensor is fixed to VB_F. Then, when using the VCM driver 10, the bias voltage of the Hall sensor may be kept fixed to VB_F.

<The process of determining the calibration formula for calibrating the output value of the sensor unit 100>

After step S200, a correction equation for correcting data 131 provided to the PID controller 140 by the sensor unit 100 and a coefficient used in the correction equation may be determined. At this time, it can be determined by dividing into two cases to be described later.

6A illustrates a graph of the first case before calibration of the Hall sensor bias voltage according to an embodiment of the present invention.

The first case is a case where VB_MAC <VB_INF, where the bias voltage is corrected such that the sensor 100 outputs the same value as the preset MIN (ex: 0) when the lens is in the macro position. . In this case, when the lens is at the infinity position, the 'sensor unit 100' is configured to output a value smaller than MAX (ex: 1023), for example, a value of E_INF (ex: 1000). That is, it may correspond to the case where the Hall sensor bias voltage VB_F = VB_MAC.

In this case, it is assumed that the user input is a command to position the lens at y = 0 (= MIN), the sensor unit 100 outputs 0 when the lens actually reaches the y = 0 position. Since the target position value y = 0 is equal to the value 0 output from the sensor unit 100, feedback control may be correctly performed at this time.

However, assuming that the user inputs a command to position the lens at y = 1023 (= MAX), the sensor unit 100 outputs 1000 when the lens actually reaches a position at y = 1023. Since the target position value 1023 is different from the output value of the sensor unit 100 by 1000, even though the lens actually reaches the target position, the PID control unit incorrectly determines that an error still exists and continues to position the lens. You may try to correct it. Therefore, feedback control cannot be performed correctly at this time. Therefore, when the lens is located at y = 1023, a scaling process of converting the output value 1000 of the 'sensor unit 100' outputted to 1023 is required.

Therefore, in this first case, the scaling correction 1 and the coefficient SF1 included in the correction 1 are determined. The coefficient SF1 is a value obtained by dividing MAX (ex: 1023) by E_INF (ex: 1000), which is a value output by the sensor unit 100 when the lens is at an infinite position.

SF1 = MAX / E_INF (ex: = 1023/1000)

The correction unit 141 of the PID controller 140 converts the value PU (position uncalibrated) output from the 'sensor unit 100' using the SF. If this converted value is called PC (position calibrated), the correction equation 1 is given by

[Calibration Formula 1]

PC = SF1 * PU

SF1 = MAX / E_INF

Since MAX is a predesigned value and E_INF is a value that can be obtained through the bias voltage calibration process of the hall sensor, calibration Equation 1 can be determined.

The PID controller 140 may determine the error value err by comparing the PC value with a value relating to a target position of the lens and a position target (PT). Feedback control may be performed such that the error value approaches zero. When the absolute value of the error value is smaller than the predetermined value, it may be determined that the lens has reached the target position and the control may be terminated.

6B illustrates a graph of a first case in which a Hall sensor bias voltage is corrected according to an embodiment of the present invention. That is, it is a graph showing the output value PC of the correction unit 141 according to the lens position to which the correction formula 1 is applied. The horizontal and vertical axes of the graph may be the same as in FIG. 6A.

6C is a graph illustrating a second case before calibration of the hall sensor bias voltage according to an exemplary embodiment of the present invention. The horizontal and vertical axes of the graph may be the same as in FIG. 6A. In the second case, VB_MAC> VB_INF is a case where the bias voltage is corrected such that the 'sensor part 100' outputs the value of MAX (ex: 1023) when the lens is at an infinite position. When the lens is in the macro position, the 'sensor unit 100' is configured to output a value larger than MIN (ex: 0), for example, a value of E_MAC (ex: 100). That is, it may correspond to the case where the Hall sensor bias voltage VB_F = VB_INF.

In this case, assuming that the user input the command to position the lens at y = 1023 (= MAX), the sensor unit 100 is MAX (ex: 1023). Since the target position value y = 1023 is equal to the value output by the sensor unit 1023, the feedback control can be correctly performed at this time.

However, assuming that the user input has a command to position the lens at y = 0 (= MIN), the sensor unit 100, when the lens actually reaches the position y = 0 (= MIN) E_MAC (ex: Will print 100). Since the target position value y = 0 is different from the E_MAC (ex: 100) output value by the sensor unit 100, the PID controller incorrectly indicates that an error still exists even though the lens has actually reached the target position. Judgment may continue to attempt to correct the position of the lens. Therefore, feedback control cannot be performed correctly at this time. Therefore, a scaling process of converting the output value E_MAC (ex: 100) of the 'sensor part 100' outputted when the lens is positioned at y = 0 to 0 is required.

Therefore, in the second case, the scaling correction equation 2 and the coefficients included in the correction equation 2 are determined. Substituting MAX into the independent variable PU of Equation 2 should output MAX to the dependent variable PC. And when E_MAC is substituted into the independent variable PU of correction 2, MIN should be output to the dependent variable PC. This correction equation 2 can be given as follows.

[Calibration 2]

PC = SF2 * PU + k

At this time, the calibration formula 2 must satisfy the following conditions.

[Condition]

MAX = SF2 * MAX + k

MIN = SF2 * E_MAC + k

In order to satisfy the above condition, each coefficient of Calibration 2 should have the following value.

SF2 = (MIN-MAX) / (E_MAC-MAX)

k = MAX-(MIN-MAX) * MAX / (E_MAC-MAX)

= MAX (1-SF2)

When the coefficients SF2 and k are determined as above, the calibration equation 2 is given by the following calibration equation 2-1.

[Calibration 2-1]

PC = PU * (MIN-MAX) / (E_MAC-MAX) + MAX-(MIN-MAX) * MAX / (E_MAC-MAX)

If MIN = 0, the equation 2 can be simplified to the equation 2-2 below.

[Calibration 2-2]

PC = -PU * MAX / (E_MAC-MAX) + MAX + MAX * MAX / (E_MAC-MAX)

  = (-PU * MAX + MAX * MAX) / (E_MAC-MAX) + MAX

  = -PU * MAX * (1-MAX) / (E_MAC-MAX) + MAX

If MIN = 0, MAX = 1023, E_MAC = 100,

Equation 2 can be given by

PC = PU * (0-1023) / (100-1023) + 1023-(0-1023) * (1023) / (100-1023)

= 1.108342 * PU-110.8342

Herein, MIN and MAX are predesigned values, and E_MAC is a value that can be obtained through the bias voltage calibration process of the Hall sensor.

6D is a graph illustrating a second case in which a Hall sensor bias voltage is corrected according to an embodiment of the present invention. That is, it is a graph showing the output value PC of the correction unit 141 according to the lens position to which the correction formula 2 is applied. The horizontal and vertical axes of the graph may be the same as in FIG. 6A.

Through the above two processes, a calibration equation for calibrating the output value PU of the sensor unit 100 including (1) the Hall sensor bias voltage and (2) the Hall sensor and the ADC of the VCM driving apparatus may be determined. This completes the calibration of the VCM drive.

Once the calibration of the VCM drive is completed, a value between MIN and MAX is input to the VCM drive through the host to perform accurate VCM feedback control.

By using the embodiments of the present invention described above, those belonging to the technical field of the present invention will be able to easily make various changes and modifications without departing from the essential characteristics of the present invention. The contents of each claim of the claims may be combined with other claims that are not cited within the scope of the claims.

Claims (8)

A sensor unit for outputting a pre-calibration position value of the current position of the lens, a driver for outputting a current provided to the VCM driving the lens, and a controller for controlling the operation of the driving unit based on the pre-calibration position value. As a VCM drive device, the VCM drive device calibration method for calibrating the state of the VCM drive device,
The sensor unit includes a Hall sensor for outputting a voltage relating to the position of the lens,
The VCM driving apparatus corrects the bias voltage provided to the hall sensor so that the pre-calibration position value output by the sensor unit when the lens is placed in the macro position becomes a first value which is designed beforehand, or the lens Calibrating the bias voltage provided to the hall sensor so that the pre-calibration position value outputted by the sensor unit becomes a second value which is previously designed when the position is set to the infinite position; And
The VCM drive converts the pre-correction position value output by the sensor portion when the lens is placed in the macro position to the first value, and outputs the sensor portion when the lens is placed in the infinity position. Calibrating the setting state of the control unit to convert the pre-calibration position value to the second value
Including,
How to calibrate VCM drive. The method of claim 1,
Receiving, by a host, a user input requesting to calibrate the VCM driver via a user interface; And
Providing, by the host, a calibration command to the VCM driver;
Further comprising,
How to calibrate VCM drive. The method of claim 1,
Correcting the bias voltage,
Setting, by the VCM driver, the bias voltage of the hall sensor to an initial value;
A first adjusting step of adjusting, by the VCM driving device, the bias voltage of the hall sensor so that the sensor unit outputs the second value while the VCM driving device maintains the lens at an infinite position;
Storing, by the VCM driving device, the bias voltage adjusted in the first adjustment step as a first bias voltage value;
Setting, by the VCM driver, the bias voltage of the hall sensor back to the initial value;
A second adjusting step of adjusting, by the VCM driving device, the bias voltage of the Hall sensor so that the sensor unit outputs the first value while the VCM driving device maintains the lens in a macro position;
Storing, by the VCM driver, the bias voltage adjusted in the second adjusting step as a second bias voltage value; And
Correcting, by the VCM driver, the bias voltage of the hall sensor to a lesser one of the first value and the second value;
Including,
How to calibrate VCM drive. The method of claim 1,
The step of calibrating the setting state of the control unit includes the step of calculating a coefficient of the first equation using the pre-calibration position value as an independent variable,
How to calibrate VCM drive. A sensor unit configured to output a pre-correction position value relating to a current position of the lens, the sensor unit including a hall sensor to output a voltage relating to the position of the lens;
A driver for outputting a current provided to the VCM for driving the lens;
A control unit controlling an operation of the driving unit based on the pre-calibration position value;
Including;
The control unit,
When the lens is placed in the macro position, the bias voltage provided to the Hall sensor may be corrected such that the pre-calibration position value outputted by the sensor unit is a first value which is designed beforehand, or the lens is placed at an infinite position. Correcting a bias voltage provided to the hall sensor so that the pre-calibration position value outputted by the sensor unit becomes a second value which is designed beforehand; And
The pre-correction position value output by the sensor unit when the lens is placed at the macro position is converted to the first value, and the pre-correction position value output by the sensor unit when the lens is placed at the infinity position. Calibrating the setting state of the control unit to convert a to the second value.
Is designed to perform
VCM drive. The method of claim 5,
The control unit, in order to perform the step of correcting the bias voltage,
Setting a bias voltage of the hall sensor to an initial value;
A first adjusting step of adjusting a bias voltage of the hall sensor so that the sensor unit outputs the second value while the VCM driving device maintains the lens at the infinity position;
Storing the bias voltage adjusted in the first adjustment step as a first bias voltage value;
Setting a bias voltage of the hall sensor back to the initial value;
A second adjusting step of adjusting a bias voltage of the hall sensor so that the sensor unit outputs the first value while the VCM driving device maintains the lens in the macro position;
Storing the bias voltage adjusted in the second adjustment step as a second bias voltage value; And
Correcting the bias voltage of the hall sensor to a lesser one of the first value and the second value;
Is designed to perform
VCM drive. The method of claim 5,
The control unit,
A correction unit which receives the pre-calibration position value and converts it into a calibrated position value and outputs it;
An error detector for calculating a difference value between the corrected position value and a position target value input by the user; And
A driving current controller configured to generate a control signal provided to the driving unit based on the difference value;
Including,
VCM drive. A lens whose focal length is controlled by the VCM; And a VCM driving device providing a driving current of the VCM.
The VCM drive device,
A sensor unit configured to output a pre-correction position value relating to a current position of the lens, and including a hall sensor to output a voltage relating to the position of the lens;
A driver for outputting a current provided to the VCM for driving the lens; And
A control unit controlling an operation of the driving unit based on the pre-calibration position value;
Including;
The control unit,
When the lens is placed in the macro position, the bias voltage provided to the Hall sensor may be corrected such that the pre-calibration position value outputted by the sensor unit is a first value which is designed beforehand, or the lens is placed at an infinite position. Correcting a bias voltage provided to the hall sensor so that the pre-calibration position value outputted by the sensor unit becomes a second value which is designed beforehand; And
The pre-correction position value output by the sensor unit when the lens is placed at the macro position is converted to the first value, and the pre-correction position value output by the sensor unit when the lens is placed at the infinity position. Calibrating the setting state of the control unit to convert a to the second value.
Is designed to perform
Auto focus control system.

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