JP2018063416A - Actuator driver, lens controller, and imaging device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hall element for lens position detection that is equipped with temperature compensation.SOLUTION: A position detection unit 510 generates a position detection value Pthat indicates the position of a control object. A temperature detection unit 520 generates a temperature detection value that indicates temperature. A correction unit 530 corrects the position detection value P. A controller 560 generates a control command value Sso that a position detection value Pafter correction and a position command value Pthat indicates the target position of the control object will match. A driver unit 570 applies a drive signal that corresponds to the control command value Sto an actuator 402. The correction unit 530 corrects the position detection value Pso that the relationship of the position detection value Pand the actual position is linearized and the relationship after linearization remains constant independently of temperature.SELECTED DRAWING: Figure 18

Description

  The present invention relates to an actuator driver, a lens control device, and an imaging device using the same.

  In recent years, an increasing number of camera modules installed in smartphones and the like incorporate a function for controlling the position of the imaging lens with high accuracy and high speed by detecting the position of the imaging lens and feeding back this position information. ing. Incorporating feedback control into the autofocus operation enables high-precision and high-speed autofocus. In addition, by incorporating feedback control as optical camera shake correction (OIS), highly accurate camera shake correction can be performed. In a camera incorporating these feedback controls, a control error may occur if the position detection signal changes with temperature. In addition, since linear control is usually performed in the OIS, linearity between the position detection signal and the actual position is also important.

  In particular, in an imaging apparatus including an imaging device capable of phase difference detection for autofocus, the imaging lens is directly displaced to the output value of the position detection signal corresponding to the in-focus position determined by phase difference detection. This enables high-speed autofocus, but if the relationship between the in-focus position and the output value of the position detection signal deviates due to a temperature change, the position deviated from the in-focus position is accessed. In other words, additional time is required before focusing. In addition, since the imaging lens is moved to the target position assuming that the relationship between the target position and the position detection signal is linear, if the linearity between the position detection signal and the displacement is shifted, A position deviated from the in-focus position is accessed. As described above, in an imaging apparatus including an imaging element capable of detecting a phase difference, both temperature compensation and linear compensation are important.

  In addition, in an imaging apparatus including a plurality of camera modules called a dual camera, it may be necessary to control the movements of the plurality of camera modules in conjunction with each other. Even in such a case, if the relationship between the position detection signal and the actual position is shifted due to temperature, the linkage between the two camera modules is lost, which may affect the generated image. is there. Furthermore, if the linearity of the relationship between the position detection signal and the displacement is shifted, the linkage between the two is also lost, which may affect the image. As described above, both temperature compensation and linear compensation are important even in an imaging apparatus including a plurality of camera modules.

  Japanese Patent Application Laid-Open No. 2004-228561 detects a temperature based on a resistance value of a shape memory alloy, and corrects an inclination component and an offset component between a control value and a displacement characteristic according to a difference between the environmental temperature and a reference temperature. An apparatus is disclosed. Patent Document 2 discloses a control circuit that performs correction using a correction function stored in advance so that the output signal of the position detection element exhibits linearity.

WO2009 / 093645 JP 2009-145635 A JP 2013-205550 A JP 2000-47084 A

  In Patent Document 1, an environmental temperature is detected based on a resistance value of a shape memory alloy, and a tilt component and an offset component between control values and displacement characteristics are corrected according to a difference between the environmental temperature and a reference temperature. Although compensation is described, the relationship between the control value and the displacement characteristic is obtained by measuring the position and control value of two points at the time of shipment from the factory and connecting the two points with a straight line to obtain the control value-displacement characteristic. Therefore, when this relationship is non-linear, no consideration is given.

  Patent Document 2 describes linear compensation that is corrected using a correction function stored in advance so that the output signal of the position detection element exhibits linearity. Not considered.

  The present invention has been made in view of such circumstances, and one of the exemplary purposes of an aspect thereof is to provide a lens control device capable of positioning an imaging lens with high accuracy and high speed.

  One embodiment of the present invention relates to a lens control device. The lens control device is based on an imaging lens, an actuator that drives the imaging lens, a Hall element that generates a position detection signal indicating the position of the imaging lens, and a voltage across the Hall element when a constant current is applied. A temperature detection unit that detects the temperature; and a control unit that controls the actuator so that the position detection signal approaches a position command signal indicating the target position of the imaging lens.

  According to this aspect, since the temperature can be detected by using the change in the internal resistance of the Hall element originally provided as the position detection element, a new temperature sensor is unnecessary, and cost and space can be reduced. Moreover, since temperature detection and position detection can be measured by voltage changes between separate terminals, temperature detection and position detection can be performed in parallel and / or continuously.

The control unit may include a temperature compensation unit that corrects the temperature dependence of the relationship between the position detection signal and the actual position of the imaging lens corresponding to the position detection signal.
By using the temperature detected using the Hall element to correct the temperature characteristic of the Hall element, accurate temperature compensation can be performed.

The control unit may further include a linear compensation unit for correcting the linearity of the relationship.
By performing both temperature compensation and linear compensation when controlling the position of the imaging lens, it is possible to position the imaging lens with high accuracy and at high speed.

A relationship at a predetermined temperature may be acquired in advance. The control unit may further include memory means for storing information related to the relationship. For the current temperature different from the predetermined temperature, the linearity is corrected based on the relationship at the predetermined temperature, and the temperature is compensated by giving a predetermined correction coefficient according to the difference between the predetermined temperature and the current temperature. May be.
According to this aspect, since the correction coefficient according to the relationship between the position detection signal at the predetermined temperature and the displacement of the imaging lens and the difference between the predetermined temperature and the current temperature is used, the memory capacity and calculation can be reduced. Both temperature compensation and linear compensation can be performed.

Relationships at a plurality of predetermined temperatures may be acquired in advance. The control unit may further include a memory unit for storing information related to the relationship. For the current temperature different from the predetermined temperature, the linearity is corrected based on the relationship among the plurality of predetermined temperatures closest to the current temperature, so that the slope of the straight line is constant regardless of the temperature. Temperature compensation may be performed.
According to this aspect, since a plurality of predetermined temperature relational expressions are used, the accuracy of temperature compensation and linear compensation can be improved, and the number of predetermined temperature conditions that need to be measured in advance is limited. Therefore, the memory capacity can be reduced.

Relationships at a plurality of predetermined temperatures may be acquired in advance. The control unit may further include a memory unit for storing information related to the relationship. For a current temperature different from the predetermined temperature, a relationship for the current temperature is generated based on a relationship between two of the plurality of predetermined temperatures sandwiching the current temperature, and linearity is generated based on the generated relationship , And temperature compensation may be performed so that the slope of the straight line is constant regardless of the temperature.
According to this aspect, since a plurality of predetermined temperature relational expressions are used, the accuracy of temperature compensation and linear compensation can be improved, and the number of predetermined temperature conditions that need to be measured in advance is limited. Therefore, the memory capacity can be reduced.

Another aspect of the present invention relates to an imaging apparatus. The imaging device may include any of the lens control devices described above and an imaging device capable of detecting a phase difference for autofocus. Temperature compensation and linear compensation may be applied to position detection of the imaging lens for autofocus.
According to this configuration, it becomes possible to directly access the target position of the in-focus position by phase difference detection based on the position detection signal subjected to temperature compensation and linear compensation. Lens positioning is possible.

Another aspect of the present invention also relates to an imaging apparatus. The imaging device may include a plurality of camera modules. Each camera module may include any of the lens control devices described above. In each camera module, temperature compensation and linear compensation may be applied to position detection of the imaging lens for autofocus.
According to this configuration, it is possible to perform the movement of the imaging lens between a plurality of camera modules while associating them, and the position detection signal is corrected even if the temperature changes. Is possible.

  Another aspect of the present invention is an actuator driver. The actuator driver includes a position detection unit that generates a position detection value indicating the position of a control target based on a Hall signal generated by the Hall element, a correction unit that corrects the position detection value, and a corrected position detection value. And a controller that generates a control command value so that the position command value indicating the target position of the control target matches, a driver unit that applies a drive signal corresponding to the control command value to the actuator, and a constant current A temperature detection unit that generates a temperature detection value indicating the temperature based on the voltage across the Hall element.

  According to this aspect, since the temperature can be detected by using the change in the internal resistance of the Hall element originally provided as the position detection element, a new temperature sensor is unnecessary, and cost and space can be reduced. Moreover, since temperature detection and position detection can be measured by voltage changes between separate terminals, temperature detection and position detection can be performed in parallel and / or continuously.

The correction unit may correct the position detection value so that the relationship between the position detection value and the actual position is linearized and the relationship after linearization is constant without depending on the temperature.
According to this aspect, the object can be positioned with high accuracy and high speed by performing both temperature compensation and linear compensation in the position control of the object.

  In the vicinity of the position of the control target corresponding to the predetermined position detection value, the position detection value may be corrected so that the relationship between the position detection value and the actual position is constant without depending on the temperature.

When the position detection value or the position command value is y, the actual position is x, and the relationship between x and y is an xy characteristic, the correction unit has a predetermined linearized xy characteristic y = ax + b and a predetermined value. A memory for holding data describing a function x = f (y) obtained by polynomial approximation of an xy characteristic measured in advance at a temperature and correction coefficients c and d (d may be zero) for each of a plurality of temperatures. May be included. Correction unit, when the position detection value from the position detecting unit and y _1,
calculating x ₁ = f (y ₁ );
calculating y ₂ = ax ₁ + b;
Determining coefficients c and d corresponding to the temperature indicated by the temperature detection value;
calculating y ₃ = cy ₂ + d;
The Run, y ₃ may be a position detection value after correction.

The function x = f (y) may be divided into a plurality of sections and approximated by a linear function for each section.
As a result, the calculation time can be shortened and the memory capacity required during the calculation can be reduced as compared with the case where all sections are approximated by a common high-order function.

  The step of determining the coefficients c and d corresponding to the temperature (detected temperature) indicated by the temperature detection value may select (i) a correction coefficient defined for the temperature closest to the detected temperature, or (ii) ) It may be calculated by calculation such as interpolation or averaging from correction coefficients defined for two temperatures sandwiching the detected temperature.

When the position detection value or the position command value is y, the actual position is x, and the relationship between x and y is an xy characteristic, the correction unit has a predetermined linearized xy characteristic y = ax + b and a predetermined value. A memory for holding data describing a function x = f ₀ (y), x = f ₁ (y),... Obtained by polynomial approximation of xy characteristics measured in advance at a plurality of temperatures T ₀ , T ₁ ,. May be included. The correction unit
Determining a function x = f ′ (y) corresponding to the temperature indicated by the temperature detection value;
A step of calculating x ₁ = f ′ (y ₁ ), where y ₁ is a position detection value from the position detection unit;
calculating y ₂ = ax ₁ + b, and
y ₂ may be the position detection value after correction.

The function x = f ′ (y) may be divided into a plurality of sections and approximated by a linear function for each section.
As a result, the calculation time can be shortened and the memory capacity required during the calculation can be reduced as compared with the case where all sections are approximated by a common high-order function.

  In the step of determining the function x = f ′ (y) corresponding to the temperature (detected temperature) indicated by the temperature detection value, (i) a function defined for the temperature closest to the detected temperature may be selected. (Ii) It may be obtained by calculation such as interpolation or averaging from functions defined for two temperatures sandwiching the detected temperature.

  The actuator driver may be integrated on a single semiconductor substrate.

  Another aspect of the present invention relates to a lens control device. The lens control device may include a lens, an actuator having a lens attached to the movable portion, and any of the above-described actuator drivers that drive the actuator.

  Another embodiment of the present invention relates to an imaging apparatus. The imaging device may include an imaging element and the lens control device described above.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  Furthermore, the description of the means for solving this problem does not explain all the indispensable features, and therefore the sub-combination of these features described can also be the present invention.

  According to the present invention, an object can be positioned with high accuracy and high speed.

It is a figure which shows an imaging device. It is a flowchart which shows the process of temperature compensation and linear compensation in 1st Embodiment of the lens control apparatus which concerns on this invention. It is a figure for demonstrating the method of calculating the inclination of the relationship between a position detection signal and displacement required when performing linear compensation. It is a figure for demonstrating the method of calculating the inclination and offset of the relationship between a position detection signal and a displacement which are needed when performing linear compensation. It is a figure which shows the measurement result explaining how the relationship between a position detection signal and displacement changes with temperature. It is a figure which shows the result of having performed linear compensation with respect to the measurement result of the relationship between the position detection signal in each temperature of FIG. 5, and a displacement. It is a figure which shows the result of having further performed temperature compensation with respect to the result of having performed the linear compensation of FIG. FIG. 8 is a diagram illustrating a result of temperature compensation using an average value of correction coefficients optimum for each of a plurality of lens control devices as a correction coefficient instead of the correction coefficient used when the temperature compensation of FIG. 7 is performed. is there. It is a figure which shows the result of having performed temperature compensation by inclination correction | amendment before performing linear compensation. It is a flowchart which shows the process of temperature compensation and linear compensation in 2nd Embodiment of the lens control apparatus which concerns on this invention. FIG. 6 is a diagram illustrating a result of performing linear compensation on the measurement result of each temperature based on the relationship between the position detection signal and displacement at each temperature in the result of FIG. 5 and performing temperature compensation so that the inclination does not change with temperature. is there. FIG. 6 is a diagram showing measurement results for explaining how this relationship changes with temperature in a lens control device having a relationship between a position detection signal and displacement different from FIG. 5. It is a figure of the result of having performed correction of inclination and offset as temperature compensation before performing linear compensation to the measurement result of FIG. The figure which shows the result of having performed temperature compensation so that linear compensation was performed with respect to the measurement result of each temperature based on the relationship between the position detection signal and displacement at each temperature in the result of FIG. is there. It is a flowchart which shows the temperature compensation and the linear compensation process in 3rd Embodiment of the lens control apparatus which concerns on this invention. It is a figure which shows the result of having performed linear compensation and temperature compensation after restrict | limiting a stroke range. It is a figure explaining the linear approximation of the function in 4th Embodiment. It is a block diagram which shows the system configuration | structure of a lens control apparatus. It is a figure which shows the temperature dependence of the resistance value of a Hall element.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  In addition, dimensions (thickness, length, width, etc.) of each member described in the drawings may be appropriately enlarged or reduced for easy understanding. Furthermore, the dimensions of the plurality of members do not necessarily represent the magnitude relationship between them, and even if one member A is drawn thicker than another member B on the drawing, the member A is the member B. It can be thinner.

  In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected to each other in addition to the case where the member A and the member B are physically directly connected. It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

  Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

In the present embodiment, an actuator driver that drives an actuator for positioning a lens will be described. First, the configuration of an actuator that moves the imaging lens will be briefly described. FIG. 1 is a diagram illustrating an imaging apparatus. The imaging device 300 is a camera module built in a digital camera, a digital video camera, a smartphone, or a tablet terminal. The imaging apparatus 300 includes an imaging element 302, a lens 304, a processor 306, and a lens control device 400. The lens 304 is disposed on the optical axis of the light incident on the image sensor 302. For example, the lens 304 may be an autofocus (AF) lens or a camera shake correction lens. The lens control device 400 positions the lens 304 based on a position command value (also referred to as a target code) P _REF from the processor 306.

For example, when the lens 304 is an AF lens, the lens control device 400 displaces the lens 304 in the optical axis direction (Z-axis direction). The processor 306 generates the position command value _PREF so that the contrast of the image captured by the image sensor 302 is increased (contrast AF). Alternatively, the position command value P _REF may be generated based on an output from an AF sensor provided outside the imaging element 302 or embedded in the imaging surface (phase difference AF).

When the lens 304 is a camera shake correction lens, the lens control device 400 displaces the lens 304 in the X-axis and / or Y-axis direction within a plane parallel to the image sensor 302. The processor 306 generates a position command value P _REF based on the output from the gyro sensor.

  In the following description, the lens 304 is described as an AF lens.

  The lens control device 400 controls the actuator 402 by position feedback. Specifically, the lens control device 400 includes an actuator 402, a position detection element 404, a temperature detection element 406, and an actuator driver IC (Integrated Circuit) 500. The actuator 402 is, for example, a voice coil motor, and its movable part is connected to the holder 308 of the lens 304. The fixed part of the voice coil motor is fixed to the housing of the imaging apparatus 300.

For the position detecting element 404, for example, a magnetic detecting means such as a Hall element is often used. A permanent magnet is attached to the movable part of the voice coil motor, and a Hall element is attached to the fixed part. When the movable portion and the fixed portion are relatively displaced, the magnetism from the permanent magnet input to the Hall element changes. The Hall element generates an electrical signal (hereinafter referred to as a position detection signal _PFB ) corresponding to a magnetic change, that is, a displacement of the actuator 402, in other words, a current position of the lens 304. Position detection signal _{P FB} is fed back to the actuator driver IC 500.

  The actuator driver IC 500 is a functional IC integrated on one semiconductor substrate. “Integration” here includes the case where all of the circuit components are formed on a semiconductor substrate and the case where the main components of the circuit are integrally integrated. Part of the resistors, capacitors, and the like may be provided outside the semiconductor substrate. By integrating the circuit on one chip, the circuit area can be reduced and the characteristics of the circuit elements can be kept uniform.

Actuator driver IC500 is fed-back position detection signal _{P FB} is, to match the position command value _{P REF,} feedback control of the actuator 402.

  By detecting the position of the lens 304 in this way and feeding it back for use in position control, it is possible to suppress transient vibration in the step response and speed up convergence, or to achieve high-speed access to the target position.

Ideally, the output of the position detection element 404 (that is, the position detection signal P _FB ) or the corresponding position command value P _REF (hereinafter also referred to as a variable y) and the actual state of the lens 304 (actuator 402). It is desirable that the relationship (hereinafter also referred to as xy characteristics) of the position (hereinafter referred to as a variable x) is linear and invariant with respect to temperature fluctuations and has no variation. In reality, however, the xy characteristics are non-linear, and there are variations among the imaging apparatuses 300, and their relationship (xy characteristics) also varies depending on the temperature of the position detection element 404. Therefore, even if the position detection signal _PFB and the position command value _PREF are controlled to coincide with each other, the actual position of the lens 304 changes if this relationship (xy characteristic) changes.

  The actuator driver IC 500 has a function of correcting xy characteristics, as will be described in detail later. For this correction, a temperature detection element 406 is provided. The temperature detection element 406 detects the temperature of the position detection element 404. Note that when the temperature of the position detection element 404 matches the ambient temperature, or when there is a strong correlation, the temperature detection element 406 may measure the ambient temperature. The detected temperature information T is input to the actuator driver IC 500. The actuator driver IC 500 corrects the drive control of the actuator 402 based on the temperature information T. The temperature detection element 406 may be a thermistor, a posistor, a thermocouple, or the like. Alternatively, as described later, when the position detection element 404 that is a temperature detection target is a Hall element, the Hall element may be used as the temperature detection element 406.

Most strictly, the following flow enables control without temperature fluctuation and individual variation.
1. Prior to product shipment, the relationship (xy characteristic) between the position detection signal y and the actual position x is measured for each of a plurality of temperatures at each of a plurality of temperatures.
2. The displacement (position) corresponding to the position detection signal is acquired by referring to one of the relationships measured in advance corresponding to the current temperature.
However, this flow requires an enormous inspection time before shipment. In addition, since it is necessary to store xy characteristics for each of a plurality of temperatures in the actuator driver IC, a large-capacity memory is required. This problem is particularly serious when the xy characteristic is nonlinear.

  In the following, correction processing for performing control while suppressing temperature fluctuations and individual variations with a small memory capacity will be described with reference to the first to third embodiments. The correction process described below is large and includes linear compensation for linearizing the position detection signal (position command value) and the actual position, and temperature compensation for correcting temperature fluctuation.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart showing the temperature compensation and linear compensation processes in the first embodiment of the lens control apparatus according to the present invention. FIG. 3 is a diagram for explaining a method of calculating the inclination of the relationship between the position detection signal and the displacement necessary for performing linear compensation. FIG. 4 is a diagram for explaining a method of calculating the inclination and offset of the relationship between the position detection signal and the displacement required when performing linear compensation. FIG. 5 shows the measurement results for explaining how the relationship between the position detection signal and the displacement changes depending on the temperature. FIG. 6 is a diagram illustrating a result of performing linear compensation on the measurement result of the relationship between the position detection signal and the displacement at each temperature in FIG. FIG. 7 is a diagram showing a result of further temperature compensation performed on the result of the linear compensation shown in FIG. FIG. 8 shows the result of the temperature compensation using the average value of the optimum correction coefficient for each of the plurality of lens control devices as the correction coefficient instead of the correction coefficient used when the temperature compensation of FIG. 7 is performed. FIG. FIG. 9 is a diagram illustrating a result of performing temperature compensation by inclination correction before performing linear compensation.

  With reference to FIG. 2, the overall processing of linear compensation and temperature compensation will be described. In the first embodiment, linear compensation at each temperature is performed using the relationship between the position detection signal and displacement at one predetermined temperature.

Processes 1 to 3 are performed in an inspection process before the shipment after the imaging apparatus 300 is manufactured. In the process 1, the relationship between the position detection signal y (position detection value P _{FB in} FIG. 1) and the displacement x (xy characteristic) at a predetermined temperature (also referred to as a reference temperature) T ₀ , for example, a temperature set in a manufacturing factory, is obtained. Get it. The position detection signal y may be an output voltage of the Hall element. When measurement is performed with servo applied, the target code (position command value P _{REF in} FIG. 1) may be used. This is because the target code is a code indicating the target access position, and when the servo is applied and converged to the target position, it becomes equivalent to the output voltage of the Hall element. The displacement x may be measured directly by using a laser displacement meter or the like. Thus the relationship between the measured position detection signal y and the displacement x in the do not necessarily linearity is maintained, it is conceivable to vary the relationship by the temperature changes from T _0. Process 1 is performed for all individuals.

In process 2, a linear function y = ax + b is set. The slope a and the intercept b of the linear function y = ax + b are preferably defined in consideration of the xy characteristics obtained in the process 1. For example, the slope a and the intercept b may be obtained by linearly approximating the xy characteristics. Incidentally, the linear function y = ax + b can be determined independently of the x-y characteristic at the reference temperature _{T 0.}

When the zero point adjustment is performed at the time of measurement, since the origin passes from the measurement stage, that is, b = 0, only the inclination a need be obtained. For example, if the measurement result is functionalized as y = g (x) as shown in FIG. 3, after differentiation, the slope at the position x ₀ near the center of the stroke is a = g ′ (x ₀ ), and y = ax can be defined as a straight line 7 having an inclination a and passing through the origin. On the other hand, when the measurement result does not pass through the origin, offset correction (b ≠ 0) may be performed and shifted so as to pass through the origin, or, as shown in FIG. Y = ax + b may be defined as a straight line 9 connecting two points (x ₀₁ , y ₀₁ ) and (x ₀₂ , y ₀₂ ) at both ends of the practical stroke range.

In process 3, the relationship (xy characteristic) between the position detection signal y and displacement x measured in process 1 is converted into a function. In a real machine such as a mobile phone, y is a measured value, so y is a variable, and a function is expressed as x = f (y). Since the function fits a relationship that is not a straight line, a function of second order or higher is required (polynomial approximation). Increasing the order reduces the fit error, but increases the amount of calculation, so the order may be set according to the actual situation. In the following linear compensation, a quintic function was used.
x = f (y) = k ₀ + k ₁ y + k ₂ y ² + k ₃ y ³ + k ₄ y ⁴ + k ₅ y ⁵ (1)

Processes 4 to 6 are processes during actual operation of the actuator driver IC 500. The value of the position detection signal y obtained from the position detection element 404 during actual operation and y _1.

In step 4, by applying a position detection signal y ₁ which is actually detected in the function equation (1), determine the displacement x ₁ of the calculation. The displacement x ₁ is the amount of temporary.
x ₁ = f (y ₁ )
If the ambient temperature is the same as T ₀ , the factory measured results should be reproduced. Even ambient temperature was different from _{T 1} and _{T 0,} using the derived function x = f (y) with respect to _{T 0.} Incidentally, the detection of temperatures T ₁ may use a temperature sensor such as a thermistor or thermocouple, but as described below, upon detecting a temperature change by utilizing the change with temperature of the resistance value of the Hall element, component Without increasing the number of points, it is possible to detect the temperature of the element itself to be detected.

In the process 5, by substituting the y = ax + b is set to _{x 1} obtained in process 4 in the process _2, obtaining a y 2 = _ax 1 + b. As a result, the measured value y ₁ is corrected to y ₂ and linear compensation is performed. This linear compensation, the use of the equation at the temperature T ₀ even temperature T _1, an error occurs according to the difference between the temperature T ₀ and the temperature T _1.

In process 6, temperature compensation is performed to correct this error. Specifically, the temperature dependence of the slope of the straight line and the offset is corrected so that y ₃ = cy ₂ + d. The coefficients c and d are parameters defined in advance for each temperature. The coefficients c and d do not need to be obtained for each individual, and an appropriate value may be defined using a representative small sample (individual) before the test. If the relational expression passes through the origin (that is, if b = 0), only correction of the inclination is necessary, and d = 0 can be set.

As described above, by performing both linear compensation and temperature compensation, a relationship between the position detection signal and the displacement having linearity and constant regardless of the temperature is obtained. Since the position detection signal and the position command value are equal when the servo is stable, the position command value and the displacement maintain a linear and stable relationship regardless of temperature and individual variations. That is, from the viewpoint of the processor 306, the lens 304 can be displaced to the same position with respect to a certain position command value _PREF regardless of temperature and variation.

  Specific measurement results and correction examples will be described with reference to the graphs of FIGS.

Figure 5 shows an example of actual measurement results of a relationship between the position detection signal y ₁ and the displacement x. Graph 10 shows the results at temperatures of 10 ° C., 15 ° C., and 35 ° C. These three temperatures are representatively shown as two temperatures having the largest change in the measured values and a temperature indicating an intermediate result. Also, the numerical value on the vertical axis of the graph depends on the magnification of the hall amplifier, and also differs depending on whether it is the hall output or the target code.Therefore, the absolute value is meaningless if it is measured under the same conditions. ing. Although the graph 10 is close to a straight line, it is actually curved, and the inclination changes with temperature.

FIG. 6 is a graph showing the result of performing linear compensation (processing 4 and 5) on the result of FIG. Although not shown in the figure, the reference temperature T _{0 serving} as a reference for functionalization was set to 25 ° C. The relationship between the position detection signal y and the displacement x measured at 25 ° C. was functionalized using a quintic equation to obtain a function of x = f (y). Next, the value of the position detection signal at each temperature was entered into this function, and a result corrected to a straight line by y = ax was obtained using a predetermined slope a. Here, the inclination a is defined as the inclination in the vicinity of the intermediate position where the displacement is in the relationship between the position detection signal at 25 ° C. and the displacement. As shown in the graph 11, the results of each temperature are corrected to a straight line. However, since the temperature is linearized using a function of 25 ° C. for all temperatures, a function error occurs and the slope varies depending on the temperature. became.

FIG. 7 shows the result of correcting the inclination of each temperature by setting an inclination correction coefficient for each temperature with respect to the result of FIG. Specifically, the correction coefficient for each temperature was set so that the slope coincided with the straight line of the reference temperature T ₀ = 25 ° C. The correction coefficient for each temperature is associated with the coefficient c in the process 6 of FIG.

For example, it is assumed that the slope at _{25 ° C.} is α _{25 ° C.} , the slope at _{10 ° C.} is α _{10 ° C.} , the slope at _{15 ° C.} is α _{15 ° C.} , and the slope at _{35 ° C.} is α _{35 ° C.} In this case, if the graph of _{10 ° C.} is multiplied by α _{25 °} C./α _{10 °} C., it matches the graph of 25 ° C. Similarly, if the graph of _{15 ° C.} is multiplied by α _{25 °} C./α _{15 °} C., it matches the graph of 25 ° C., and if the graph of _{35 ° C.} is multiplied by α _{25 °} C./α _{35 °} C., the graph of 25 ° C. Matches.

Therefore, the correction coefficient c _{10 ° C.} in the process 6 of FIG. 2 at a temperature of 10 ° _C. is obtained as α _{25 °} C./α _{10 ° C.} Similarly, the correction coefficient c _{15 °} C. at a temperature of 15 ° _C. is α _{25 °} C./α _{15 ° C.,} and the correction coefficient c _{35 °} C. at a temperature of 35 ° _C. is obtained as α _{25 °} C./α _{35 ° C.}

The correction coefficients C _{10 ° C.} , C _{15 ° C.} , and C _{35 ° C.} thus obtained may be stored as a table in the memory of the lens control device. If the detected temperature detected by the temperature detecting means is in the middle of the temperatures set in the table (10, 15, 35 ° C. in this example), the correction coefficient defined for the two temperatures sandwiching the detected temperature May be used, or the correction coefficient may be calculated by linear interpolation. Further, the correction coefficient may be held as a function of temperature. As a result of performing linear compensation and temperature compensation, the graph 12 is almost in a straight line regardless of the temperature. This position detection signal y ₃ obtained by processing 6 during the actual operation of the actuator driver IC500 is meant to represent with high accuracy the actual position x.

When viewed from the processor 306, the position command value P _REF (y) and the actual position x of the lens 304 always satisfy the relation y = ax + b without depending on the temperature or the like. As a result, the lens 304 can be accurately and rapidly positioned as a whole system.

  In FIG. 7, as the correction coefficient c for each temperature, an optimum value is set for a small number of representative samples actually measured. However, there are individual variations in the correction coefficient, and optimal correction is not always possible with the same value. Although an optimal correction coefficient may be set in advance for each individual, for that purpose, it is necessary to measure temperature characteristics for each individual, and productivity is lowered. If there is individual variation, a correction coefficient distribution may be obtained from the measurement results of a plurality of individuals, and for example, an average value or the like may be used as the correction coefficient setting value. FIG. 8 shows the result when the inclination is corrected with the average value of the correction coefficient. As described above, the correction error of the tilt occurs in the graph 13 due to the influence of the individual variation of the correction coefficient, but the error can be improved as compared with the case where the tilt correction is not performed at all (FIG. 6).

  Note that the flow of FIG. 2 shows an example, and does not prescribe all the processing order. For example, it may be possible to obtain a constant correction value regardless of the temperature while performing curvature correction by performing inclination correction for each temperature first, and then linearize using one function. FIG. 9 shows the result of the inclination correction for each temperature before linearization. Although the curve remains, it becomes almost the same curve regardless of the temperature. That is, since the same curve is linearized with one function, there is almost no function error at the time of linearization, and the graph 14 becomes almost one straight line regardless of temperature even after linearization. As in this example, in the case of a sample having relatively good linearity, almost the same correction result can be obtained by either method.

  However, it is difficult to find the optimum inclination correction value and offset correction value for the curved characteristic before linearization. In other words, linearization is first performed as shown in FIG. 2 and offset correction is also performed at the time of linearization (passing through the origin, b = 0). By setting d = 0), highly accurate correction is possible, and calculation of the coefficient for correction is facilitated. Further, even if tilt correction for each temperature and, in some cases, offset correction are performed, the same curve may not be obtained regardless of temperature. In such a case, even if linearization is performed after temperature correction, the gradient after linearization differs depending on the temperature, and it is necessary to perform gradient correction again. Therefore, in such a case, it is easier to perform processing after performing linearization first and then performing temperature correction.

Second Embodiment
A second embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a flowchart showing temperature compensation and linear compensation processing in the second embodiment of the lens control apparatus according to the present invention. FIG. 11 shows the result of performing linear compensation on the measurement result of each temperature based on the relationship between the position detection signal and displacement at each temperature in the result of FIG. 5, and performing temperature compensation so that the inclination does not change with temperature. FIG.

  The flow of FIG. 10 is significantly different from the flow of FIG. 2 in that a function measured under a plurality of temperature conditions is used as a function for linearization. Since a function indicating the temperature characteristic at the time of linearization or a function close thereto can be used, a function error due to linearization can be reduced, and as a result, a correction error can be reduced.

In the process 15, the relationship between the position detection signal y and the displacement x is obtained at a plurality of predetermined temperatures T ₀ , T ₁ , T ₂ . If there are many temperature conditions to be set, the error in functioning due to the deviation from the actual temperature can be reduced, so the accuracy of correction can be improved, but the number of preliminary temperature measurement steps increases, so the balance between required accuracy and process cost The condition number can be set with.

In the process 16, a linear function y = ax + b in the case of linearization is set. That is, the inclination a and the intercept b are determined. When the zero point adjustment is performed at the time of measurement, since the origin passes from the measurement stage, that is, b = 0, only the inclination a need be obtained. Here, since the characteristic passes through the origin as in the first embodiment, the slope a at T ₀ is obtained as the representative temperature. By using this same slope when linearizing other temperatures, temperature compensation can be performed simultaneously with linear compensation.

  In the process 17, the relationship between the measured position detection signal y and the displacement x is converted into a function. In a real machine such as a mobile phone, y is a measured value, so y is a variable and is expressed as a function such as x = f (y). Since the function fits a relationship that is not a straight line, a function of second order or higher is necessary. Increasing the order reduces the fit error, but increases the amount of calculation, so the order may be set according to the actual situation. In the following linear compensation, a quintic function was used. The above functionalization is performed on the result of each temperature condition measured in advance.

In process 18, actually it detected position detection signal y ₁ by applying to these functional expression, obtaining the displacement x ₁ of the calculation. If the ambient temperature is the same as T ₀ , T ₁ , T ₂ ..., The same temperature function is used. If there is no function of the same temperature condition, the function of the closest temperature condition is used. Alternatively, a new function may be generated by interpolating functions of temperature conditions on both sides of the actual temperature. Since it is difficult to generate a complex function, a new function may be generated by multiplying a coefficient that averages the slopes of the two functions.

In process 19, x ₁ obtained in process 18 is substituted for y = ax + b set in process 16 to obtain y ₂ = ax ₁ + b. As a result, the measured value y ₁ is corrected to y ₂ and linear compensation is performed. In the first embodiment, slope correction is performed as temperature compensation thereafter. However, by using a function for each temperature, the error in functionalization can be reduced, and the slope is set to a single value a. At the same time, tilt correction is also performed. Of course, if there is no perfect function data and a functionalization error remains, tilt correction may be performed again.

  FIG. 11 is a graph showing the result of performing linear compensation on the result of FIG. The temperature used as the standard of functionalization was set to each temperature, that is, 10 ° C., 15 ° C., and 35 ° C. The relationship between the position detection signal y and the displacement x measured at each temperature shown on the left was functionalized using a quintic equation to obtain a function of x = f (y). Next, the value of the position detection signal at each temperature was entered into this function, and a result corrected to a straight line by y = ax was obtained using a predetermined slope a. By using the same inclination a for linearization at any temperature, inclination correction is performed simultaneously with linearization. The graph 20 is almost a straight line regardless of the temperature, and the correction error can be further reduced compared to the result of FIG. This result is linearized by applying the function of each temperature to that temperature, so it is natural that it becomes a straight line, and the actual temperature is slightly different from the functionalized temperature condition, so the correction error increases. End up. In order to improve the accuracy of linear compensation and temperature compensation even if time is taken, it is better to create a database of characteristics under as many temperature conditions as possible.

  Next, an example of linear compensation and temperature compensation in a lens control device having other characteristics will be described. FIG. 12 shows measurement results for explaining how this relationship changes with temperature in a lens control device having a relationship between a position detection signal and displacement different from FIG. FIG. 13 is a diagram showing a result of correcting the slope and offset as temperature compensation for the measurement result of FIG. 12 before performing linear compensation. FIG. 14 shows the result of performing linear compensation on the measurement result of each temperature based on the relationship between the position detection signal and displacement at each temperature in the result of FIG. 13, and performing temperature compensation so that the inclination does not change with temperature. FIG.

  In FIG. 12, a graph 21 shows results at temperatures of 5 ° C., 30 ° C., and 50 ° C., and a characteristic difference due to temperature occurs. These three temperatures are representatively shown as two temperatures having the largest change in the measured values and a temperature indicating an intermediate result. The result of FIG. 12 is significantly different from the result of FIG. 5 in that the linearity is deteriorated. The inclination varies greatly depending on the stroke range.

  FIG. 13 shows the result of the inclination correction for each temperature before the linearization is performed on the result of FIG. At the same time as the tilt correction, offset correction was also performed, which was converted to a graph passing through the origin. The graph 22 does not match the results for each temperature while the curve remains. That is, although the tilt correction is performed on the side where the displacement is small, the same tilt correction is not appropriate in a region where the displacement is large, and a deviation occurs. That is, in the case of such characteristics, temperature compensation cannot be performed only by tilt correction and offset correction. Even if it is implemented, the error becomes large. Therefore, even if this result is linearized, a large error occurs.

  In the case of such characteristics, it is desirable to use function data for each temperature according to the flow of FIG. 10 and linearize for each temperature. 5 ° C. FIG. 14 shows a result obtained by linearizing each temperature using a function based on measurement data at each temperature of 30 ° C. and 50 ° C., and correcting the inclination for each temperature so that the inclination is the same. The graph 23 is substantially one straight line, and both linear compensation and temperature compensation can be realized.

<Third Embodiment>
A third embodiment of the present invention will be described with reference to FIGS. FIG. 15 is a flowchart showing temperature compensation and linear compensation processing in the third embodiment of the lens control device according to the present invention. FIG. 16 is a diagram illustrating a result of performing linear compensation and temperature compensation after limiting the stroke range.

As shown in FIG. 12, when the linearity of each temperature is performed using the function of each temperature when the linearity is poor, correction with a relatively small error is possible, but a function of each temperature is prepared. This requires extra time and memory capacity. FIG. 15 is a flowchart showing another correction method. 1 is different from the flow of FIG. 1 in that, when the relationship between the position detection signal and the displacement at the predetermined temperature T ₀ is acquired, if it is determined that the linearity is poor and high-precision linear compensation and temperature compensation cannot be realized, The control range is limited so that the stroke range with poor characteristics is cut and only the stroke range that can be corrected is used.

In the process 24, the relationship between the position detection signal y and the displacement x is obtained at a predetermined temperature T ₀ , for example, a set temperature of a manufacturing factory.

  In the process 25, it is judged from the result of the process 24, and the stroke range that can be used for the control is limited. After limiting the stroke, offset correction may be performed so that the limited stroke position becomes the origin.

  In the process 26, a linear function y = ax + b in the case of linearization is set. When the offset correction is performed first, it passes through the origin, i.e., b = 0, so only the slope a need be obtained.

  In the process 27, the relationship between the measured position detection signal y and the displacement x is converted into a function. In a real machine such as a mobile phone, y is a measured value, so y is a variable and is expressed as a function such as x = f (y). Since the function fits a relationship that is not a straight line, a function of second order or higher is necessary. Increasing the order reduces the fit error, but increases the amount of calculation, so the order may be set according to the actual situation. In the following linear compensation, a quintic function was used.

In step 28, by applying a position detection signal y ₁ which is actually detected in the function equation to determine the displacement x ₁ of the calculation. If the ambient temperature is the same as T ₀ , the factory measured results should be reproduced. Even ambient temperature was _{T 1} changed from _{T 0,} using the derived function x = f (y) with respect to _{T 0.}

In step 29, by substituting the y = ax + b is set to _{x 1} obtained in processing 28 in the process 26 _obtains a y 2 = _ax 1 + b. As a result, the measured value y ₁ is corrected to y ₂ and linear compensation is performed. This linear compensation, the use of the equation at the temperature T ₀ even temperature T _1, an error occurs according to the difference between the temperature T ₀ and the temperature T _1.

In process 30, temperature compensation is performed so as to correct this error. Specifically, the inclination and offset of the straight line are corrected, and y ₃ = cy ₂ + d is set. If the relational expression passes through the origin, it is only necessary to correct the inclination.

  FIG. 16 shows the result of performing linear compensation and temperature compensation after limiting the stroke range in this way. In the graph 31, linear compensation and temperature compensation can be realized with high accuracy, although some correction errors remain.

  In addition, it was explained that the stroke range with poor linearity was cut, but this is a display on the graph. It is not always necessary to prevent the detection signal from being output, and it is only necessary to allow a deviation in linearity and a change in temperature in such a range.

  In this way, when it is difficult to ensure linearity over the entire stroke range and suppress changes due to temperature, it is necessary to ensure linearity at a predetermined position and predetermined stroke range, and to suppress changes due to temperature, so that at least Performance in that range is improved. What position and what stroke range should be optimized for linear compensation and temperature compensation may be selected according to the purpose. For example, in the case of AF linear compensation and temperature compensation, if landscape photography is important, linear compensation and temperature compensation near infinity should be optimized. The linear compensation and temperature compensation in the vicinity of the lens position corresponding to the distance may be optimized. Further, in the case of OIS linear compensation and temperature compensation, the linear compensation and temperature compensation in the vicinity of the centering setting position and the neutral neutral position of the spring when no blur signal is input may be optimized.

<Fourth embodiment>
A fourth embodiment of the present invention will be described with reference to FIG. FIG. 17 is a diagram illustrating a method for linearly approximating a function in the fourth embodiment. In the first to third embodiments, when the relationship between the position detection signal y and the image displacement x at the predetermined temperature T ₀ is a curve, it is used for correction processing as a high-order function, for example, a quintic function. . However, in the case of performing linear compensation in an actual imaging apparatus, if such a quintic function is performed, it takes a long time to calculate, and the memory capacity required during the calculation also increases. Therefore, the function x = f (y) may be divided into a plurality of sections and approximated by a linear function for each section. Although there is a possibility that the calculation accuracy is slightly lowered, an actuator having an xy characteristic that shows a smooth change has little influence even by linear interpolation. If the stroke range of AF and OIS of a normal camera module is used, linear interpolation by connecting about 16 to 20 points is sufficient.

In FIG. 17, measurement points are indicated by circles, and a high-order function fitted to the data at these points is indicated by a broken line, and a result approximated by connecting the points by a straight line is indicated by a solid line. If there is a sufficient number of points, there will be no significant difference in results even when connecting straight lines to higher-order functions. The values of x and y at each measurement point may be stored in a memory as a correction table. In the process 5, etc. in FIG. 2, when the position detection signal y ₁ between the measurement point is detected, using the data of the measurement points on both sides, by obtaining the value of x ₁ as a linear function connecting these two points Good.

  If the points are connected with a straight line, it seems that it may be connected with a straight line without functioning from the beginning, but if the measurement result of the selected point happens to be a singular point containing a noise component, it will be a straight line as it is. When connected, the result is rattling. Actually, since it is considered that there is a smoother change, it is better to make it into a smooth curve once functioned and approximate it by connecting straight lines. When converting to a function, it is preferable to select a function that minimizes the mean square of errors from the measurement points, instead of deriving a function that passes through all the measurement points.

Next, a specific configuration example of the lens control device 400 will be described.
FIG. 18 is a specific block diagram of the lens control device 400. The position detection element 404 is the Hall element 32, generates Hall voltages V ₊ and V ₋ corresponding to the displacement of the movable part of the actuator 402, and supplies them to the Hall detection pins (HP, HN) of the actuator driver IC 500.

The position detection unit 510 generates a digital position detection value _PFB indicating the position (displacement) of the movable part of the actuator 402 based on the Hall voltages V ₊ and V ₋ . The position detection unit 510 includes a hall amplifier 512 that amplifies the hall voltage, and an A / D converter 514 that converts the output of the hall amplifier 512 into a digital position detection value _PFB .

  The temperature detection unit 520 generates a temperature detection value T indicating the temperature. As described above, it is desirable that the temperature indicates the temperature of the position detection element 404. In FIG. 18, the Hall element 32 that is the position detection element 404 is also used as the temperature detection element 406. This utilizes the fact that the internal resistance r of the Hall element 32 has temperature dependence. The temperature detector 520 measures the internal resistance r of the Hall element 32 and uses it as information indicating the temperature.

Temperature detection unit 520 includes a constant current circuit 522 and an A / D converter 524. The constant current circuit 522 supplies a predetermined bias current I _BIAS to the Hall element 32. The bias current I _BIAS is also a power supply signal necessary for operating the Hall element 32. Therefore, the constant current circuit 522 can be grasped as a Hall bias circuit.

A voltage drop I _BIAS × r is generated between both ends of the Hall element 32. This voltage drop is input to the Hall bias pin (HB). The A / D converter 524 converts the voltage V _HB (= I _BIAS × r) of the HB pin into a digital value T. Since the bias current I _BIAS is known and constant, the digital value T is a signal proportional to the internal resistance r, and therefore includes information on the temperature of the Hall element 32. The relationship between the internal resistance r and the temperature is measured in advance, converted into a function, or tabulated, and the digital value T is converted into temperature information in the correction unit 530 at the subsequent stage.

The interface circuit 540 receives a target code TC indicating the target position of the movable part of the actuator 402 from the processor 306. For example, the interface circuit 540 may be a serial interface such as I ² C (Inter IC). The filter 550 filters the target code TC received by the interface circuit 540 to generate a position command value P _REF . If the position command value P _REF changes abruptly, the position of the lens 304 may ring. This ringing is suppressed by the filter 550.

Correcting unit 530 corrects the position detection value _{P FB} from the position detection unit 510. Specifically, the correction unit 530 includes a linear compensation unit 532, a temperature compensation unit 534, and a memory 536. The linear compensation unit 532 corrects the linearity of the relationship between the position detection value _PFB and the actual position (the above-described xy characteristic). The memory 536 stores the above-described parameters a and b, data describing the function x = f (y) (for example, coefficients k _{0 to} k ₅ ), parameters c and d, and the like. The memory 536 may be a nonvolatile memory such as a ROM or a flash memory, or may be a volatile memory that temporarily holds data supplied from an external ROM each time the circuit is activated.

The temperature compensation unit 534 corrects the relationship between the position detection value _PFB and the actual position from changing due to a temperature change.

  For example, in the first embodiment, the process of the linear compensation unit 532 corresponds to the processes 4 and 5 in the flowchart of FIG. 2, and the process of the temperature compensation unit 534 corresponds to the process 6 of the flowchart in FIG.

  In the second embodiment, the process of the linear compensation unit 532 corresponds to the process 19 of the flowchart of FIG. 10, and the process of the temperature compensation unit 534 corresponds to the process 18 of the flowchart of FIG. 10.

  In the third embodiment, the process of the linear compensation unit 532 corresponds to the processes 28 and 29 in the flowchart of FIG. 15, and the process of the temperature compensation unit 534 corresponds to the process 30 of the flowchart in FIG. 50.

Controller 560 receives position command value P _REF and position detection value P _{FB — CMP} after correction by correction unit 530. The controller 560 generates the control command value S _REF so that the position detection value P _{FB_CMP} matches the position command value P _REF . When the actuator 402 is a voice coil motor, the control command value _SREF is a command value of a drive current to be supplied to the voice coil motor. The controller 560 includes an error detector 562 and a PID controller 564, for example. The error detector 562 generates a difference (error) ΔP between the position detection value P _{FB_CMP} and the position command value P _REF . The PID controller 564 generates a control command value _SREF by PID (proportional / integral / derivative) calculation. Instead of the PID controller 564, a PI controller may be used, or nonlinear control may be employed.

The driver unit 570 supplies a drive current corresponding to the control command value S _REF to the actuator 402.

As can be seen from FIG. 18, the Hall voltages V ₊ and V ₋ from the Hall element 32 are output from a terminal different from the application of the control current. That is, unlike the shape memory alloy, there is no mixing of a component due to temperature change and a component due to displacement in the resistance value change, and both position detection and temperature detection can be achieved with high accuracy.

  The processing of the correction unit 530 and the controller 560 may be realized by hardware such as an adder or a multiplier, or may be realized by a combination of a CPU and a software program.

  FIG. 19 is a diagram showing the temperature dependence of the resistance value of the Hall element. A black circle shows a measurement result, and a broken line is a linear approximation of this change. As described above, the temperature change can be detected by using the change in the resistance value of the Hall element due to the temperature. Since a constant bias current is flowing, a change in resistance value can be detected as a change in the bias voltage of the Hall element. As shown in FIG. 19, the relationship between the temperature and the Hall bias voltage shows a substantially straight line, and it can be seen from this result that the temperature change can be detected by monitoring the change in the Hall bias voltage.

  A feature to be noted here is that the temperature change of the resistance on the bias side that is driven by constant current is monitored as a voltage change, not a change of the output of the Hall element due to the temperature. When the output voltage of the Hall element is monitored, it is difficult to detect only the temperature change purely due to the temperature characteristics of the Hall element and the temperature characteristics of the Hall amplifier and magnetic flux density. . However, when the voltage change on the bias side is monitored, the temperature can be detected because the variation factor due to temperature is almost limited to the resistance change of the element.

  In FIG. 18, the temperature detected using the Hall element is used for temperature compensation of the relationship between the position detection signal and the actual position, but this is not restrictive. The detected temperature may be used for temperature abnormality detection and protection (thermal shutdown) associated with the temperature abnormality. Alternatively, the detected temperature may be stored in a register and read out from the CPU 306.

  The lens control device as described above is used in a camera module for a mobile phone. In particular, one suitable application of the lens control device of the present invention is an imaging device having an imaging device having a phase difference detection function. By using phase difference detection, it is possible to determine the focus shift and direction, so the necessary amount of change in the position detection signal from the current position to the in-focus position can be determined by correlating with the position detection signal in advance. The in-focus state can be obtained directly by accessing the code position of the target position detection signal. However, since linear calculation is used when calculating the amount of change in the position detection signal up to the target position, linearization of the relationship between the position detection signal and the displacement is important in order to reduce the position error. . Furthermore, if this relationship changes depending on the temperature, even if it is displaced to the position of the code number of the target position, it will deviate from the target position, so temperature compensation is also important. By using the present invention, both linear compensation and temperature compensation can be achieved. Therefore, the present invention is preferably applied to an imaging apparatus having an imaging element having a phase difference detection function.

  Another preferred application of the lens control device of the present invention is an imaging device equipped with a plurality of cameras such as a dual camera. An application is considered in which two cameras are linked to obtain a zoom image, for example, by synthesizing images from the two cameras. In this case, a means for interlocking the lens positions of the two cameras is a position detection signal. Even if calibration is performed so that the two can be linked in the initial state and linear compensation is performed, if this relationship is shifted due to temperature, a positional error may occur, which may affect the image. In particular, when the temperature characteristics of the two cameras are different, there is an error in the command to move to a predetermined position, but there is a difference in the amount of deviation, so that correct position control cannot be performed with uniform temperature compensation. By using the present invention, both linear compensation and temperature compensation can be achieved, and compensation can be executed for each camera. Therefore, the present invention is preferably applied to an imaging apparatus equipped with a plurality of cameras such as a dual camera. is there.

DESCRIPTION OF SYMBOLS 300 ... Image pick-up device 302 ... Image pick-up element 304 ... Lens, 306 ... Processor, 400 ... Lens control apparatus, 402 ... Actuator, 404 ... Position detection element, 406 ... Temperature detection element, 500 ... Actuator driver IC, 510 ... Position detection 512, Hall amplifier, 514, A / D converter, 520, Temperature detection unit, 522, Constant current circuit, 524, A / D converter, 530, Correction unit, 532, Linear compensation unit, 534, Temperature compensation unit, 540 ... Interface circuit, 550 ... Filter, 560 ... Controller, 562 ... Error detector, 564 ... PID controller, 570 ... Driver part, 32 ... Hall element.

Claims (18)

An imaging lens;
An actuator for driving the imaging lens;
A hall element that generates a position detection signal indicating the position of the imaging lens;
A temperature detector that detects a temperature based on a voltage across the Hall element when a constant current is applied;
A control unit that controls the actuator so that the position detection signal approaches a position command signal indicating a target position of the imaging lens;
A lens control device comprising:   The lens control device according to claim 1, wherein the control unit includes a temperature compensation unit that corrects a temperature dependency of a relationship between the position detection signal and a corresponding actual position of the imaging lens.   The lens control device according to claim 2, wherein the control unit further includes a linear compensation unit for correcting linearity of the relationship. The relationship at a predetermined temperature is acquired in advance,
The control unit further includes memory means for storing information on the relationship,
For a current temperature different from the predetermined temperature, the linearity is corrected based on the relationship at the predetermined temperature, and
4. The lens control device according to claim 3, wherein temperature compensation is performed by giving a predetermined correction coefficient according to a difference between the predetermined temperature and the current temperature. The relationship at a plurality of predetermined temperatures is acquired in advance,
The control unit further includes memory means for storing information related to the relationship,
For a current temperature different from the predetermined temperature, the linearity is corrected based on the relationship in one of the plurality of predetermined temperatures closest to the current temperature, and
4. The lens control device according to claim 3, wherein temperature compensation is performed so that the slope of the straight line is constant regardless of temperature. The relationship at a plurality of predetermined temperatures is acquired in advance,
The control unit further includes memory means for storing information related to the relationship,
For a current temperature different from the predetermined temperature, a relationship for the current temperature is generated based on the relationship in two of the plurality of predetermined temperatures sandwiching the current temperature,
While correcting linearity based on the generated relationship,
4. The lens control device according to claim 3, wherein temperature compensation is performed so that the slope of the straight line is constant regardless of temperature. A lens control device according to any one of claims 1 to 6;
An image sensor capable of phase difference detection for auto-focusing;
With
An imaging apparatus, wherein temperature compensation and linear compensation are applied to position detection of the imaging lens for autofocus. With multiple camera modules,
Each camera module includes the lens control device according to any one of claims 1 to 6,
An image pickup apparatus, wherein temperature compensation and linear compensation are applied to position detection of an image pickup lens for autofocus in each camera module. A position detection unit that generates a position detection value indicating a position of a control target based on a Hall signal generated by the Hall element;
A correction unit for correcting the position detection value;
A controller that generates a control command value so that the corrected position detection value matches a position command value indicating the target position of the control target;
A driver unit for applying a drive signal corresponding to the control command value to the actuator;
A temperature detection unit that generates a temperature detection value indicating a temperature based on a voltage across the Hall element when a constant current is applied; and
An actuator driver comprising:   The correction unit corrects the position detection value so that the relationship between the position detection value and the actual position is constant without depending on the temperature in the vicinity of the position of the control target corresponding to the predetermined position detection value. The actuator driver according to claim 9.   The correction unit corrects the position detection value so that the relationship between the position detection value and the actual position is linearized and the relationship after linearization is constant without depending on temperature. The actuator driver according to claim 9 or 10. When the position detection value or the position command value is y, the actual position is x, and the relationship between x and y is xy characteristics,
The correction unit is
Data describing a target linearized xy characteristic y = ax + b, a function x = f (y) obtained by polynomial approximation of an xy characteristic measured in advance at a predetermined temperature; A memory for holding correction coefficients c and d (d may be zero);
The correction unit is
Calculating x ₁ = f (y ₁ ), where y ₁ is the position detection value from the position detection unit;
calculating y ₂ = ax ₁ + b;
Determining coefficients c and d corresponding to the temperature indicated by the temperature detection value;
calculating y ₃ = cy ₂ + d;
Is executed, the actuator driver according to claim 11, characterized in that y ₃ is the position detection value after correction.   The actuator driver according to claim 12, wherein the function x = f (y) is divided into a plurality of sections and approximated by a linear function for each section. When the position detection value or the position command value is y, the actual position is x, and the relationship between x and y is xy characteristics,
The correction unit is
A function x = f ₀ (y), a polynomial approximation of a target linearized xy characteristic y = ax + b and an xy characteristic measured in advance at a plurality of predetermined temperatures T ₀ , T ₁ ,. including a memory holding data describing x = f ₁ (y),.
The correction unit is
Determining a function x = f ′ (y) corresponding to the temperature indicated by the temperature detection value;
Calculating x ₁ = f ′ (y ₁ ), where y ₁ is the position detection value from the position detection unit;
calculating y ₂ = ax ₁ + b;
The actuator driver according to claim 11, wherein y ₂ is the position detection value after correction.   The actuator driver according to claim 14, wherein the function x = f ′ (y) is divided into a plurality of sections and approximated by a linear function for each section.   16. The actuator driver according to claim 9, wherein the actuator driver is integrated on a single semiconductor substrate. A lens,
An actuator having the lens attached to a movable part;
The actuator driver according to any one of claims 9 to 15, which drives the actuator;
A lens control device comprising: An image sensor;
A lens control device according to claim 17;
An imaging apparatus comprising:

Images