JP2004354321A - Position detector, position detection method, and imager - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detector and an imager, in which the correction of a dark current of a PSD can be performed simply with a high performance. <P>SOLUTION: The device operates as follows: a light is emitted by an IRED 231; the light from the IRED 231 is received by the PSD 232; a photocurrent is output corresponding to a light receiving position of a light receiving face; a sum voltage corresponding to a sum current of the photocurrent output from the PSD 232 is detected by an adding circuit 43 under the switching-off condition of the light emitting part; a correction coefficient &alpha;px is calculated by a correction coefficient calculation part 51 from the detected sum voltage; and using a unit conversion circuit 187, a difference voltage corresponding to a difference current from the PSD 232 is converted to a position data by the correction coefficient &alpha;px calculated by the correction coefficient calculation part 51. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a position detection device, and more particularly to a position detection device for detecting a position of a photographic lens of a camera, a position detection method, and an imaging device using the position detection device.
[0002]
[Prior art]
Conventionally, a moving member having a photographing lens or the like is coupled to a rod-shaped driving member so as to have a predetermined frictional force, and an impact-type piezoelectric actuator formed by fixing a piezoelectric element to one end of the driving member. The following drive devices are known. When the piezoelectric actuator having this configuration is used for a focus lens, a zoom lens, a camera shake correction lens, and the like, it is necessary to control the position of the moving member in order to accurately perform focus adjustment, magnification adjustment, camera shake correction, and the like. Therefore, such a driving device is provided with a position detecting device for detecting the position of the taking lens. In this position detecting device, light from a light emitting element (IRED) is received by a semiconductor position detecting element (PSD), and the position of the moving member is detected by detecting a current corresponding to a light receiving position on the PSD.
[0003]
However, since the PSD is configured by a photoelectric conversion member such as a photodiode, a dark current depending on temperature is generated, and the dark current may adversely affect detection accuracy.
[0004]
Therefore, in the conventional position detecting device, a dark current holding means for holding a dark current voltage corresponding to the dark current of the PSD is provided, and the output current of the PSD is equivalent to the dark current voltage held by the dark current holding means by the subtraction circuit. The influence of the dark current is avoided by subtracting the current to be performed (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-7-239249
[0006]
[Problems to be solved by the invention]
However, in the position detecting device of Patent Document 1, it is necessary to constantly maintain the dark current voltage in order to detect the dark current, which complicates the circuit configuration and, for example, causes errors in mounting and problems in the system configuration. Therefore, when the relative distance between the IRED (light emitting unit) and the PSD (light receiving unit) changes, it is difficult to correct the PSD output current.
[0007]
The present invention has been made in order to solve the above-described problem, and provides a position detection device, a position detection method, and an imaging device that can easily and easily perform correction of dark current of a light receiving unit. The purpose is.
[0008]
[Means for Solving the Problems]
A position detecting device according to the present invention includes a light emitting unit that emits light, a light receiving unit that receives light from the light emitting unit and outputs a current according to a light receiving position on a light receiving surface, and a state in which the light emitting unit is turned off. A dark current detector that detects a current output from the light receiver as a dark current; and a dark current included in the current output from the light receiver based on the dark current detected by the dark current detector. A correction coefficient calculating unit for calculating a correction coefficient for eliminating the difference current, and position data for detecting a difference current from the light receiving unit and converting the difference current into position data based on the correction coefficient calculated by the correction coefficient calculation unit. A conversion unit.
[0009]
According to this configuration, light is emitted by the light emitting unit, light from the light emitting unit is received by the light receiving unit, and a current corresponding to a light receiving position on the light receiving surface is output. A current output from the light receiving unit is detected as a dark current by the dark current detecting unit in a state where the light emitting unit is turned off, and is output from the light receiving unit based on the detected dark current by the correction coefficient calculating unit. A correction coefficient for removing a dark current included in the current is calculated, a difference data from the light receiving unit is detected by the position data conversion unit, and the difference current is calculated based on the correction coefficient calculated by the correction coefficient calculation unit. Is converted to
[0010]
Therefore, in a state where the light emitting unit is turned off, the current output from the light receiving unit is detected as a dark current, and based on the detected dark current, the dark current included in the current output from the light receiving unit is removed. Since the correction coefficient is calculated and converted into position data by multiplying the difference current of the current output from the light receiving section by the correction coefficient, the dark current of the light receiving section can be corrected with high performance and easily. Can be.
[0011]
Further, in the above-described position detection device, it is preferable that the correction coefficient calculation unit calculates the correction coefficient from the dark current detected by the dark current detection unit at a predetermined timing.
[0012]
According to this configuration, the correction coefficient is calculated from the dark current detected by the dark current detector at a predetermined timing. Therefore, a dark current generated under the influence of temperature rise due to aging is detected at a predetermined timing, and based on the dark current detected at the predetermined timing, the dark current included in the current output from the light receiving unit is determined. Since the correction coefficient for removing the image is calculated, the dark current of the light receiving unit can be corrected in real time according to the temperature rise.
[0013]
Further, in the above-described position detecting device, the position detecting device further includes a measuring unit for measuring an elapsed time from when the power is turned on, and when the elapsed time measured by the measuring unit reaches a predetermined time, the correction coefficient It is preferable that the calculation unit calculates the correction coefficient from the dark current detected by the dark current detection unit.
[0014]
According to this configuration, the elapsed time from when the power is turned on is measured by the measurement unit, and when the elapsed time measured by the measurement unit reaches a predetermined time, the dark current detection unit detects the elapsed time. Based on the dark current, a correction coefficient for removing the dark current included in the current output from the light receiving unit is calculated. Therefore, when the temperature of the light-receiving unit is low immediately after the power is turned on, the amount of dark current generated is small, so that the process of calculating the correction coefficient from the dark current detected by the dark current detection unit is not performed, Calculating a correction coefficient for removing a dark current included in the current output from the light receiving unit based on the dark current detected by the dark current detecting unit when the elapsed time of the predetermined time has elapsed. Is performed, it is possible to reduce the load on the process for correcting the dark current.
[0015]
Further, the position detection method according to the present invention includes a step of emitting light from a light emitting unit, and, in a state where the light emitting unit is turned off, receiving light from the light emitting unit and generating a current corresponding to a light receiving position on a light receiving surface. Detecting a current output from the light receiving unit as a dark current, and calculating a correction coefficient for removing a dark current included in the current output from the light receiving unit based on the detected dark current. And a step of detecting a difference current from the light receiving unit and converting the difference current into position data using the correction coefficient.
[0016]
According to this configuration, light is emitted by the light emitting unit, light from the light emitting unit is received by the light receiving unit, and a current corresponding to a light receiving position on the light receiving surface is output. Then, with the light emitting unit turned off, the current output from the light receiving unit is detected as a dark current, and based on the detected dark current, the dark current included in the current output from the light receiving unit is removed. A correction coefficient is calculated, a difference current from the light receiving unit is detected, and the difference current is converted into position data by the correction coefficient.
[0017]
Therefore, in a state where the light emitting unit is turned off, the current output from the light receiving unit is detected as a dark current, and based on the detected dark current, the dark current included in the current output from the light receiving unit is removed. A correction coefficient is calculated, and the difference current is converted into position data by multiplying the difference current of the current output from the light receiving section by the correction coefficient. Therefore, the correction of the dark current of the light receiving section is performed with high performance and is simplified. Can be done.
[0018]
An image pickup apparatus according to the present invention is an image pickup apparatus including a camera shake correction optical system for correcting camera shake, wherein an actuator for driving the camera shake correction optical system and a current position of the camera shake correction optical system are detected. A position detection unit that calculates a control target position of the camera shake correction optical system, and a calculation unit that calculates the control target position of the camera shake correction optical system so that the camera shake correction optical system follows the control target position. A drive control unit that controls the drive of the actuator in accordance with the difference, wherein the position detection unit receives a light from the light emission unit, and receives light from the light emission unit according to a light receiving position on a light receiving surface. A light receiving unit that outputs a current, a dark current detecting unit that detects a current output from the light receiving unit as a dark current in a state where the light emitting unit is turned off, and a dark current that is detected by the dark current detecting unit. A correction coefficient calculating section for calculating a correction coefficient for removing a dark current included in the current output from the light receiving section, and a difference current from the light receiving section detected by the correction coefficient calculating section. A conversion unit that converts the difference current into a current position of the optical system for camera shake correction using the corrected correction coefficient.
[0019]
According to this configuration, the camera shake correction optical system for correcting camera shake is driven by the actuator, and the current position of the camera shake correction optical system is detected by the position detection unit. In the position detection unit, light is emitted by the light emitting unit, light from the light emitting unit is received by the light receiving unit, and a current corresponding to the light receiving position on the light receiving surface is output. A current output from the light receiving unit is detected as a dark current by the dark current detecting unit in a state where the light emitting unit is turned off, and is output from the light receiving unit based on the detected dark current by the correction coefficient calculating unit. A correction coefficient for removing a dark current included in the current is calculated, a difference current from the light receiving unit is detected by the position data conversion unit, and the difference current is calculated by the correction coefficient calculated by the correction coefficient calculation unit. The current position of the correction optical system is converted. The control unit calculates the control target position of the camera shake correction optical system according to the difference between the current position and the control target position so that the camera shake correction optical system follows the control target position. Thus, the driving of the actuator is controlled.
[0020]
Therefore, in a state where the light emitting unit is turned off, the current output from the light receiving unit is detected as a dark current, and based on the detected dark current, the dark current included in the current output from the light receiving unit is removed. A correction coefficient is calculated, and the difference current is converted to the current position of the optical system for camera shake correction by multiplying the difference current of the current output from the light receiving unit by the correction coefficient. Can be performed easily and with high performance, and the dark current of the light receiving unit is corrected, so that highly accurate camera shake correction can be realized.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and description thereof will be omitted.
[0022]
FIG. 1 is a block diagram schematically illustrating a configuration of a camera with a camera shake correction function according to the present embodiment.
[0023]
In FIG. 1, a camera 1 with a camera shake correction function according to the present embodiment includes a camera body 2 and a photographing lens 3. The camera body 2 includes a P shake detection gyro 11, a Ya shake detection gyro 12, a shake detection circuit 13, a shake amount detection circuit 14, a coefficient conversion circuit 15, a release button 16, a sequence control circuit 17, and a control circuit 18. The photographing lens 3 includes a Y-direction position sensor 21, a Y-direction drive actuator 22, an X-direction position sensor 23, an X-direction drive actuator 24, a drive circuit 25, a temperature sensor 26, a camera shake correction optical system 27, and a photographing optical system 28. Be composed. In the present embodiment, the horizontal direction with respect to the camera 1 is defined as the X-axis direction, the vertical direction with respect to the camera 1 is defined as the Y-axis direction, the rotation direction around the X-axis is defined as the pitch (P) direction, and the Y-axis direction is defined. Is the yaw (Ya) direction.
[0024]
First, the camera body 2 will be described. The release button 16 enters a shooting preparation state in a half-pressed state. In this shooting preparation state, an auto focus (AF) for automatically focusing on a subject, an auto exposure (AE) for automatically determining an exposure, and a camera shake correction function are operated. The camera shake correction function continues to operate during the half-pressed state to facilitate framing. When the release button 16 is fully pressed by the photographer, photographing is performed. That is, according to the exposure state determined by the AE, the exposure control is performed so that an image sensor (not shown) is properly exposed. In a dark place, the shutter speed becomes low and camera shake occurs. During this time, appropriate shake correction control is performed so as to correct image shake due to camera shake.
[0025]
The P shake detection gyro 11 is a gyro sensor that detects the shake of the camera in the Y direction, and the Ya shake detection gyro 12 is a gyro sensor that detects the shake of the camera in the X direction. The gyro sensor detects the angular velocity of the shake when the measurement target (the camera in the present embodiment) is rotated by the shake. The gyro sensor has a piezoelectric element, and vibrates by applying a voltage to the piezoelectric element. When an angular velocity due to rotational motion is applied to the piezoelectric element, Coriolis force is generated in a direction perpendicular to the vibration direction, and the piezoelectric element is distorted. The gyro sensor detects the angular velocity by extracting this distortion as an electric signal.
[0026]
The P shake angular velocity signal detected by the P shake detection gyro 11 and the Ya shake angular velocity signal detected by the Ya shake detection gyro 12 are input to a shake detection circuit 13. The shake detection circuit 13 includes a filter circuit (a low-pass filter and a high-pass filter) for reducing noise and drift from each angular velocity signal, and an amplification circuit for amplifying each angular velocity signal.
[0027]
Each angular velocity signal output from the shake detection circuit 13 is input to the shake amount detection circuit 14. The shake amount detection circuit 14 captures each angular velocity signal at predetermined time intervals, and outputs the camera shake amount in the X direction as detx and the shake amount in the Y direction as dety to the coefficient conversion circuit 15.
[0028]
The coefficient conversion circuit 15 converts the shake amount (detx, dety) in each direction into the movement amount (px, py) in each direction while correcting according to the individual variation of the camera shake correction optical system 27 and the ambient temperature. The individual variation of the camera shake correction optical system 27 is, for example, stored in a memory (not shown) mounted on the camera body in an inspection at the time of shipment of the camera body. Temperature characteristics are also measured and stored in the memory.
[0029]
The signals indicating the movement amounts (px, py) in each direction output from the coefficient conversion circuit 15 are input to the control circuit 18. The control circuit 18 considers an environmental change or a temporal change due to the temperature of the drive circuit 25, the X and Y direction drive actuators 24 and 22, and the X and Y direction position sensors 23 and 21, and the amount of movement (px, py) is converted to an actual drive signal (drvx, drvy).
[0030]
The drive signals (drvx, drvy) in each direction output from the control circuit 18 are input to the drive circuit 25.
[0031]
The operations of the shake amount detection circuit 14, the coefficient conversion circuit 15, and the control circuit 18 are controlled by a sequence control circuit 17. That is, when the release button 16 is fully pressed, the sequence control circuit 17 controls the shake amount detection circuit 14 to capture the shake amounts (detx, dety) in each direction. Next, the sequence control circuit 17 controls the coefficient conversion circuit 15 to convert the amount of shake in each direction into the amount of movement (px, py) in each direction. Next, the sequence control circuit 17 controls the control circuit 18 to calculate an operation value based on the amount of movement in each direction. In order to correct the camera shake, such an operation is repeatedly performed at regular time intervals during a period from when the release button 16 is fully pressed and the exposure is completed. Here, camera shake, so-called hand shake, is caused by vibration of a muscle having a small amplitude of about 10 Hz, shaking of a body having a large amplitude of 3 Hz or less, and operating the release button 16 having a large amplitude of about 5 Hz. The resulting deflection is said to be a combined vibration. For this reason, in the present embodiment, camera shake correction is performed at, for example, 0.0005 second intervals (2 kHz).
[0032]
When the release button 16 is half-pressed, the sequence control circuit 17 uses a circuit (not shown) to prepare for photographing such as photometry and object distance detection, and when the release button 16 is fully pressed, a focus adjustment circuit is provided. An operation of taking a picture by driving a lens is also performed.
[0033]
Next, the photographing lens 3 will be described. The temperature sensor 26 is, for example, a thermistor, and detects the ambient temperature and outputs a detection result to the coefficient conversion circuit 15 and the control circuit 18 of the camera body 2. The detection result is used to correct a characteristic change due to temperature. For example, the correction includes correction for a temperature change of the camera shake correction optical system 27 and the position sensors 21 and 23 in each direction, and correction of the basic drive frequency and the drive voltage of the drive actuators 22 and 24 in each direction. These operations are performed by previously storing an LU table indicating a correction value for temperature for each characteristic in the above-described memory (not shown) in the camera body 2.
[0034]
The imaging optical system 28 forms subject light from the subject on the imaging surface. The camera shake correction optical system 27 is a lens for correcting camera shake and refracts subject light from the subject.
[0035]
The Y direction position sensor 21 detects the position of the camera shake correction optical system 27 in the Y direction, and outputs the detection result to the drive circuit 25. The Y direction drive actuator 22 is, for example, an impact type piezoelectric actuator using a piezoelectric element, and moves the camera shake correction optical system 27 in the Y direction according to the drive voltage output from the drive circuit 25. The X direction position sensor 23 detects the position of the camera shake correction optical system 27 in the X direction, and outputs the detection result to the drive circuit 25. The X direction drive actuator 24 is, for example, an impact type piezoelectric actuator using a piezoelectric element, and moves the camera shake correction optical system 27 in the X direction according to the drive voltage output from the drive circuit 25.
[0036]
The Y-direction position sensor 21 and the X-direction position sensor 23 are configured by mounting, for example, an infrared light emitting diode (IRED) and a slit on a movable side, and mounting position sensors (PSD, Position Sensitive Devices) on a fixed side. You. Each output of the Y-direction position sensor 21 and the X-direction position sensor 23 is input to the control circuit 18. The drive circuit 25 supplies a drive voltage to each of the Y-direction drive actuator 22 and the X-direction drive actuator 24 based on a control signal output from the control circuit 18 of the camera body 2.
[0037]
Next, the configuration of the camera shake correction optical system unit will be described.
[0038]
FIG. 2 is a diagram schematically showing a configuration of the camera shake correction optical system unit.
[0039]
2, the camera shake correction optical system unit 4 includes a Y direction drive actuator 22, an X direction drive actuator 24, a camera shake correction optical system 27, a base 30, a base plate 31, a lens frame 32, a Y direction slide shaft 34y, and an X direction slide. It comprises a shaft 34x, a Y-direction slide guide 35y, an X-direction slide guide 35x, a Y-direction sub-guide 36y, and an X-direction sub-guide 36x.
[0040]
The base 30 is a member on which each part of the camera shake correction optical system unit 4 is mounted. The base 30 is fixed to the lens barrel of the photographing lens 3. The X-direction drive actuator 24 is, for example, an impact-type piezoelectric actuator having a fixed element structure, and is fixed and mounted in one direction of the base 30. The direction in which the moving member 241x of the X-direction drive actuator 24 moves is defined as the X direction.
[0041]
The X-direction slide guide 35x is a substantially U-shaped power transmission member having a pair of convex sliders at both ends of a base. The base of the X-direction slide guide 35x is fixed to the moving member 241x, and the ends of the pair of sliders have one end fixed to the base and the other end fixed to the base plate 31, respectively. I have. The pair of sliders has a hole through which the X-direction slide shaft 34x penetrates, and is movable along the X-direction slide shaft 34x. The X-direction slide shaft 34x is spaced from the base 30 so that the X-direction slide guide 35x can move along the X-direction slide shaft 34x, and both ends thereof are fixed to the base 30. On the other hand, the slider of the X-direction sub-guide 36x is fixed to the base plate 31 on the side opposite to the side to which the X-direction slide guide 35x is fixed. The X-direction sub guide 36x includes a slider and a slider shaft. The slider of the X-direction sub-guide 36x has a hole penetrating through the slider shaft, and the slider shaft is spaced from the base 30 so that the slider can move along the slider shaft. It is fixed to the base 30. Thus, the X-direction sub guide 36x assists the X-direction slide guide 35x so that the base plate 31 moves smoothly in the X direction, and also supports the base plate 31 so as not to be inclined in the optical axis direction.
[0042]
The Y-direction drive actuator 22 is, for example, an impact-type piezoelectric actuator having a fixed-element structure, and is fixed to and mounted on the base plate 31 so as to be orthogonal to the X direction.
[0043]
The Y-direction slide guide 35y is a substantially U-shaped power transmission member having a pair of convex sliders at both ends of a base. The base of the Y-direction slide guide 35y is fixed to the moving member 221y, and the ends of the pair of sliders have one end fixed to the base and the other end fixed to the lens frame 32, respectively. I have. The pair of sliders has a hole through which the Y-direction slide shaft 34y penetrates, and is movable along the Y-direction slide shaft 34y. The Y-direction slide shaft 34y is spaced from the base plate 31 so that the Y-direction slide guide 35y can move along the Y-direction slide shaft 34y, and both ends thereof are fixed to the base plate 31. On the other hand, the slider of the Y-direction sub-guide 36y is fixed to the lens frame 32 on the side opposite to the side to which the Y-direction slide guide 35y is fixed. The Y-direction sub guide 36y includes a slider and a slider shaft. The slider of the Y-direction sub-guide 36y has a hole passing through the slider shaft, and the slider shaft is spaced from the base plate 31 so that the slider can move along the slider shaft. Are fixed to the base plate 31. Thus, the Y-direction sub-guide 36y assists the Y-direction slide guide 35y so that the lens frame 32 moves smoothly in the Y direction, and also supports the lens frame 32 so as not to tilt in the optical axis direction. The lens frame 32 is a holding member that holds the camera shake correction optical system 27.
[0044]
With such a configuration, the camera shake correction optical system 27 controls the subject light while continuously following the X direction and the Y direction under the optimal control (speed) state under the position servo control by the control circuit 18. Refracted in the direction of. As a result, camera shake correction becomes possible.
[0045]
Next, the control circuit 18 and its peripheral circuits will be further described.
[0046]
FIG. 3 is a block diagram showing the configuration of the control circuit and its peripheral circuits. In addition, since the camera shake correction is performed in the X direction and the Y direction, a configuration for controlling the X direction drive actuator 24 and a configuration for controlling the Y direction drive actuator 22 are required. Since these two configurations are the same, FIG. 3 shows a configuration for controlling the X-direction drive actuator 24 and omits the configuration for controlling the Y-direction drive actuator 22. In the following description, the configuration for controlling the Y-direction drive actuator 22 is omitted.
[0047]
3, the control circuit 18 includes a subtraction circuit 180, a PID 181, an LU table circuit (LUT) 182, a DAC 183, a PWM controller 184, a PWM circuit 185, a drive frequency determination circuit 186, a unit conversion circuit 187, and an ADC 188. You. The drive circuit 25 includes a voltage change circuit 251 and an H-bridge circuit 252. The X-direction position sensor 23 includes an IRED 231, a PSD 232, and a PSD signal processing circuit 233.
[0048]
The infrared light of the IRED 231 attached to the moving member of the X-direction drive actuator 24 is incident on the PSD 232 through the slit. The PSD 232 detects the infrared rays and outputs the detection result to the PSD signal processing circuit 233. The PSD signal processing circuit 233 processes the detection result into an analog voltage indicating the current position pxn of the moving member, that is, the current position pxn of the camera shake correction optical system 27, and sends the analog voltage to the ADC 188 of the control circuit 18. Output.
[0049]
The ADC 188 is an analog / digital conversion circuit that converts an analog voltage indicating the current position pxn of the camera shake correction optical system 27 into a 10-bit (bit) digital signal and outputs the digital signal to the unit conversion circuit 187. The unit conversion circuit 187 multiplies the signal indicating the current position converted into a digital signal by a fixed number (Kps times) so as to have the same unit as the target position px input from the coefficient conversion circuit 17, and generates the signal in the PSD 232. The dark current correction coefficient αpx for correcting the dark current is multiplied.
The signal indicating the current position multiplied by Kps and multiplied by the dark current correction coefficient αpx is input to the drive frequency determination circuit 186 and the subtraction circuit 180 to which the signal indicating the target position px is input.
[0050]
The drive frequency determination circuit 186 calculates the drive frequency based on the basic drive frequency of the actuator, which is the drive frequency under specific conditions, in consideration of the individual variation and the temperature characteristics of the camera shake correction optical system 27. That is, the drive frequency determination circuit 186 calculates the drive frequency by correcting the basic drive frequency according to the individual variation of the camera shake correction optical system 27 and the ambient temperature. The individual variation of the camera shake correction optical system 27 at the drive frequency is stored in the above-mentioned memory (not shown) mounted on the camera body, for example, by actually measuring the correction value in an inspection at the time of shipment of the camera body. Let it. By actually measuring the temperature characteristics of the driving frequency, a correction value of the basic driving frequency is stored in the memory as a temperature correction table for each temperature. The signal indicating the drive frequency calculated by the drive frequency determination circuit 186 is input to the PWM controller 184. Since the basic drive frequency is corrected by the drive frequency determination circuit 186 in this manner, the appropriate basic drive frequency can be obtained even if there is a variation in the image quality of the camera shake correction optical system 27 or a change in temperature.
[0051]
On the other hand, the signal indicating the target position px input from the coefficient conversion circuit 17 to the control circuit 18 is subtracted by the subtraction circuit 180 by a signal indicating the current position pxn. The subtracted control deviation signal is input to the PID 181. The PID 181 determines proportional, differential, and integral gains so as to provide optimal operation values for the difference between the target position px and the current position pxn. The control deviation signal amplified by this gain is input from the PID 181 to the LU table circuit 182 and the PWM controller 184.
[0052]
The LU table circuit 182 determines the voltage value of the DC power supply voltage Vp of the drive voltage according to the control deviation signal with reference to the voltage LU table in the memory. The determined drive voltage value is input to the DAC 183. Here, the LU table circuit 182 sets a gain of a non-linear portion, which is difficult to set with a proportional gain, a differential gain (gain of a high-frequency component), and the like. For example, in the case of the present driving device, from the viewpoint of responding to a dead zone in which operation is not performed due to friction even when 0 to 1.5 V is applied, 1.5 V is output even when a control value of the value is input, and the driving device is driven. The maximum value of the applied voltage is limited in order to avoid unnecessary high temperature of the driving device from the viewpoint of ensuring the durability of the driving device. This LU table is tabulated so as to realize, for example, the characteristics shown in FIG.
That is, when the input voltage is -5.5 V or less, the output voltage is constant at -5.5, and when the input voltage is -5.5 V or more and less than 0 V, (output voltage) = (4 / 5.5). When the input voltage is 0 V or more and 5.5 V or less, the proportional relationship of (output voltage) = (4 / 5.5) × (input voltage) +1.5 so that a proportional relationship of × (input voltage) −1.5 is obtained. And the output voltage is constant at 5.5 V when the input voltage is 5.5 V or more.
[0053]
The DAC 183 is a digital / analog conversion circuit, converts the voltage value of the drive voltage into an analog voltage in 8 bits, and inputs the analog voltage to the drive circuit 25. As a result, when the drive circuit 25 is the circuit shown in FIG. 14, the DC power supply voltage Vp is changed to the voltage value of the drive voltage determined by the LU table circuit 182. As a result, the moving member, that is, the camera shake correction optical system 27 continuously moves at predetermined time intervals so that the camera shake correction is performed while the shutter is opened and the subject image is captured (exposed). .
[0054]
Further, the PWM controller 184 determines the moving direction of the camera shake correction optical system 27 according to the sign of the control deviation signal from the PID 181, and accordingly sets the duty ratio D to 3: 7 in the case of the forward direction and to the reverse direction in the case of the forward direction. In the case of, set 7: 3. The PWM controller 184 outputs a control signal to the PWM circuit 185 so as to generate a rectangular wave voltage at the drive frequency calculated by the drive frequency determination circuit 186 and at the set duty ratio D. The PWM circuit 185 generates a square-wave drive voltage in this state, and supplies the drive voltage to the H-bridge circuit 252 of the drive circuit 25. As the H-bridge circuit 252, for example, a circuit illustrated in FIG. 14 is used.
[0055]
The electromechanical transducer of the X-direction drive actuator 24 is driven by the H-bridge circuit 252, and the X-direction drive actuator 24 moves the camera shake correction optical system 27 toward the target position at a predetermined speed. Then, the control circuit 18 applies an optimum applied voltage to the H bridge circuit 252 with respect to the difference between the latest target position px and the current position pxn by the PID circuit 181, the LUT 182 and the DAC 183, and the drive frequency determination circuit 186 and the PWM. By continuously supplying the optimal drive pulse signal from the controller 184 and the PWM circuit 185 to the H-bridge circuit 252, the image stabilization optical system 27 is continuously driven, and the image stabilization is continuously performed while the shutter is open. It is possible to do.
[0056]
Next, the operation of the camera with a camera shake correction function according to the present embodiment will be described.
[0057]
When the release button 16 is fully depressed by the photographer, the sequence control circuit 17 detects the angular velocities in the respective directions detected by the P shake detection gyro 11 and the Ya shake detection gyro 12 to correct the shake. Using the coefficient conversion circuit 14 and the coefficient conversion circuit 15, the signal is converted into a signal indicating a target position (px, py) in each direction in which the camera shake correction optical system 27 is to be moved, and is input to the control circuit 18.
[0058]
Since the operations of the X-direction drive actuator 24 and the Y-direction drive actuator 22 are the same, the operation of the X-direction drive actuator 24 will be described below.
[0059]
The control circuit 18 acquires a signal indicating the current position pxn of the camera shake correction optical system 27 from the X-direction position sensor 23. The signal indicating the current position pxn is converted into a digital signal by the ADC 188, and then converted into the same unit as the signal indicating the target position px by the unit conversion circuit 187. The converted signal indicating the current position pxn is input to the drive frequency determination circuit 186 and the subtraction circuit 180 that subtracts the signal indicating the target position px.
[0060]
The subtraction circuit 180 calculates a control deviation signal by subtracting the current position pxn from the target position px, and the control deviation signal is output to the LU table circuit 182 and the PWM controller 184 after the above processing is performed by the PID 181. You. The LU table circuit 182 determines the voltage value Vpx of the drive voltage by referring to the voltage LU table based on the control deviation signal. After the determined voltage value Vpx is converted into an analog signal by the DAC 183, it is input to the voltage change circuit 251 of the drive circuit 25, and the value of the DC power supply voltage of the drive circuit 25 is set to the voltage value Vpx.
[0061]
On the other hand, the driving frequency determination circuit 186 refers to a temperature correction table stored in a memory (not shown) based on the ambient temperature detected by the temperature sensor 26, triggered by the input of the signal indicating the current position pxn. Thus, the correction value corresponding to the detected ambient temperature is determined. The drive frequency determination circuit 186 determines the drive frequency by correcting the basic drive frequency stored in the memory based on the correction value based on the individual variation and the correction value based on the ambient temperature stored in the memory. The determination of the drive frequency does not necessarily need to be performed for each position servo control of the feedback of the camera shake correction, and may be performed only at the time of startup or once every several times.
[0062]
The signal indicating the determined drive frequency is input to the PWM controller 184 together with the output of the PID 181. The PWM controller 184 determines the moving direction of the moving member, that is, the movement direction of the camera shake correction optical system 27 from the sign of the output of the PID 181, and determines the duty ratio D based on the result of the determination. That is, when moving in the forward direction, the duty ratio D is determined to be 3: 7, and when moving in the reverse direction, the duty ratio D is determined to be 7: 3. Then, the PWM controller 184 controls the PWM circuit 185 to supply the H-bridge circuit 252 of the drive circuit 25 with the PWM signal having the corrected drive frequency and the determined duty ratio D. The H-bridge circuit 252 moves the moving member at a predetermined speed by driving the electromechanical conversion element of the X-direction drive actuator 24 in accordance with the PWM signal supplied with the DC power supply voltage at the voltage value Vpx. That is, the camera shake correction optical system 27 is moved at a predetermined speed.
[0063]
The control circuit 18 continuously controls the position of the camera shake correction optical system 27 at a predetermined time interval while the shutter is opened to capture (expose) a subject image.
That is, the control circuit 18 determines an optimum control voltage from the latest target position px and the latest current position pxn, and repeatedly drives the X-direction drive actuator 24 at a speed according to the voltage value. Here, the latest target position px is calculated based on the output signal of the Ya shake detection gyro 12, and the latest current position pxn is obtained from the output signal of the X-direction position sensor 23. In the position servo control, basically, when the position deviation (difference between px and pxn) and the speed deviation are large, the applied voltage value of the electromechanical transducer of the X-direction drive actuator 24 becomes large, and the driving speed becomes low. Optimized to be fast. As a result, the camera shake correction optical system 27 can be continuously driven in a state where the deviation from the target position px is small.
[0064]
As described above, in the present embodiment, since the frequency of the drive voltage is set to the basic drive frequency, it is not necessary to control the drive frequency when controlling the speed and position of the camera shake correction optical system 27. In the present embodiment, the driving state of the camera shake correction optical system 27 is optimized by adjusting the voltage value of the drive voltage, and high-performance camera shake correction can be performed. Further, in the present embodiment, the impact-type piezoelectric actuator is used as a driving device of the camera shake correction optical system 27, so that the size of the photographing lens 3 can be reduced and power consumption can be reduced. Therefore, the size and power consumption of the camera can be reduced.
[0065]
Here, a specific configuration of the X-direction position sensor 23 will be described. FIG. 5 is a diagram showing a specific configuration of the X-direction position sensor 23. In the following description, the X-direction position sensor 23 will be described, and the Y-direction position sensor 21 has the same configuration, and a description thereof will be omitted.
[0066]
The IRED 231 emits light toward the PSD 232 by causing the internal light emitting chip 231h to emit light. A slit S is provided between the IRED 231 and the PSD 232. The slit S is a slit for narrowing a light beam emitted from the IRED 231 to sharpen directivity. As shown in FIG. 5, the slit S is narrower on the light receiving unit side than on the light emitting unit side in order to suppress energy loss of light emitted from the IRED 231 and sharpen directivity. In this embodiment, the IRED 231 is attached to the moving member of the X-direction drive actuator 24. However, in the following description using FIG. 5, the IRED 231 is described as being directly attached to the camera shake correction optical system 27. I do. Since the IRED 231 is attached to the camera shake correction optical system 27, when the camera shake correction optical system 27 moves in the X direction, the IRED 231 also moves in the X direction. Light from the IRED 231 is narrowed by the slit S and enters the PSD 232.
[0067]
The PSD 232 has a PIN structure including a P layer on the surface of silicon, an N layer on the back surface, and an I layer intermediate the P layer and the N layer. Electrodes a and b are provided at both ends of the P layer, and a portion between the electrodes a and b in the P layer is a light receiving surface. The light incident on the light receiving surface of the PSD is photoelectrically converted and divided and output as a photocurrent from the electrodes a and b attached to the P layer. When the spot light is incident on the PSD, an electric charge proportional to the light energy is generated at the incident position. The generated charges pass through the resistance layer (P layer) as a photocurrent and are output from the electrodes a and b. Since the resistance layer is made to have a uniform resistance value on the light receiving surface, the photocurrent is divided and taken out in inverse proportion to the distance (resistance value) to the electrodes a and b. Here, the distance between the electrodes a and b of the PSD is L, and the photocurrent is I ₀ And the current drawn from the electrodes a and b is I ₁ , I ₂ And the distance from the center of the PSD to the incident position of the incident light is x _A Then, the following equation (1) is obtained.
(I ₂ −I ₁ ) / (I ₁ + I ₂ ) = 2x _A /L...(1)
[0068]
As shown in the above equation (1), the photocurrent I ₀ Total current (I ₁ + I ₂ ) Is constant, the difference current (I ₂ −I ₁ ), The distance x _A Can be calculated.
[0069]
The light output from the IRED 231 is narrow in the X direction, which is the movement detection direction, and spreads like a band in a direction perpendicular to the X direction (Y direction). Therefore, the X direction position sensor 23 can detect only the detection direction (X direction) of itself, and even if the camera shake correction optical system 27 moves in the other direction (Y direction), the slit light on the PSD 232 surface is detected. Does not change, and the position detection signal is not affected.
[0070]
FIG. 6 is a block diagram showing a configuration of the PSD signal processing circuit 233 and its peripheral circuits shown in FIG. 6, the PSD signal processing circuit 233 includes current / voltage conversion circuits 41 and 42, an addition circuit 43, a light source current control unit 44, a subtraction circuit 45, and an amplification LPF circuit 46. The control circuit 18 includes a correction coefficient calculation unit 51 and a unit conversion circuit 187.
[0071]
The current / voltage conversion circuit 41 outputs a current I output from one electrode a of the PSD 232. ₁ To the voltage VI ₁ Convert to The current / voltage conversion circuit 42 outputs the current I output from the other electrode b of the PSD 232. ₂ To the voltage VI ₂ Convert to
[0072]
The addition circuit 43 outputs the voltage VI converted by the current / voltage conversion circuit 41. ₁ And the voltage VI converted by the current / voltage conversion circuit 42 ₂ And the sum current (I ₁ + I ₂ ) (VI) ₁ + VI ₂ ) Is calculated. The light source current control unit 44 controls the light source (IRED) 231 so that the sum voltage added by the adding circuit 43 becomes a constant value.
[0073]
The subtraction circuit 45 outputs the voltage VI converted by the current / voltage conversion circuit 42. ₂ VI converted by the current / voltage conversion circuit 41 ₁ And the difference current (I ₂ −I ₁ ), The difference voltage (VI ₂ -VI ₁ ) Is calculated. The amplification LPF circuit 46 amplifies the voltage subtracted by the subtraction circuit 43 so as to have an optimum amplitude for position detection, and removes unnecessary noise components.
[0074]
The correction coefficient calculation unit 51 calculates a dark current correction coefficient for removing a dark current included in the photocurrent output from the PSD 232 from the photocurrent output from the PSD 232, and converts the calculated dark current correction coefficient into a unit. Output to the circuit 187. The dark current correction coefficient will be described later.
[0075]
FIG. 7 is a diagram illustrating an example of a specific circuit configuration of the PSD signal processing circuit.
[0076]
The switch SW 1 is a switch for switching on / off of a circuit power supply, and applies a power supply voltage Vcc to each operational amplifier in the PSD signal processing circuit 233 based on a PWRON signal input from the control circuit 18. When the L-level PWRON signal is input to the switch SW1, the circuit power is turned off. When the H-level PWRON signal is input to the switch SW1, the circuit power is turned on. The switch SW2 is a switch for turning on / off the IRED 231 and applies the power supply voltage Vcc to the IRED 231 based on the IREDON signal input from the control circuit 18. When the L-level IREDON signal is input to the switch SW2, the IRED 231 is turned off (turned off), and when the H-level IREDON signal is input to the switch SW2, the IRED 231 is turned on (lit).
[0077]
First, the PSD 232 detects the center of gravity of the light emitted from the light source (IRED) 231. Current I from electrode a of PSD232 ₁ Is output, and the current I is supplied from the electrode b. ₂ Is output. Current I output from electrode a ₁ Is output to the current / voltage conversion circuit 41, and the current I output from the electrode b is ₂ Is output to the current / voltage conversion circuit 42. The current / voltage conversion circuit 41 outputs the current I output from the electrode a of the PSD 232. ₁ Is converted to an easily detectable voltage value, and the current I ₁ VI converted from ₁ Is output to the subtraction circuit 45 and the addition circuit 43. The current / voltage conversion circuit 42 outputs the current I output from the electrode b of the PSD 232. ₂ Is converted to an easily detectable voltage value, and the current I ₂ VI converted from ₂ Is output to the subtraction circuit 45 and the addition circuit 43. The subtraction circuit 45 outputs the voltage VI ₂ From the voltage VI ₁ Is output to the amplification LPF circuit 46. The addition circuit 43 outputs the voltage VI ₁ And voltage VI ₂ And outputs the sum voltage VAND to the light source current control unit 44 and the correction coefficient calculation unit 51 of the control circuit 18.
[0078]
The amplification LPF circuit 46 outputs the difference voltage VDIF (= VI ₂ -VI ₁ ) Is amplified by a predetermined factor α so as to be optimal for the ADC range of the control circuit 18, and unnecessary high-frequency noise is removed (LPF). The difference voltage VDIF (= VI) amplified by a predetermined multiple α ₂ -VI ₁ ) Is output to the control circuit 18 as the voltage Vn corresponding to the actual position of the camera shake correction optical system 27.
[0079]
The light source current control unit 44 controls the sum current value (I) output from the PSD even when there are individual variations in the IRED 231 and changes with time. ₁ + I ₂ ) Is controlled to a constant value. In the present embodiment, control is performed so that the control voltage value IRVREF is 0.9 V higher than the reference voltage value ICVREF. Sum voltage VAND (= VI ₁ + VI ₂ ) Becomes a voltage value higher than the control voltage IRVREF (= ICVREF + 0.9), the output of the comparator becomes L level, and the control transistor is turned off. On the other hand, when the sum voltage VAND becomes a voltage value lower than the control voltage IRVREF, the output of the comparator becomes H level (substantially a voltage value), and the control transistor is turned on to flow a current to the IRED 231.
By feeding back this processing at a high speed, the output of the sum voltage VAND becomes equal to the control voltage IRVREF and is stabilized.
[0080]
Here, the dark current of the PSD will be described. FIG. 8 is a diagram for explaining the dark current of the PSD. In FIG. 8, the horizontal axis represents the light receiving position of the PSD, and the vertical axis represents the position voltage (ADIN) of the PSD. The dark current is a current flowing out of the PSD in a state where light emission of the IRED is turned off, that is, in a dark state. The dark current of the PSD varies greatly and increases by the temperature coefficient depending on the temperature. As shown in FIG. 8, when there is a dark current, the slope of the characteristic representing the relationship between the light receiving position of the PSD and the position voltage becomes gentler than when there is no dark current. The difference in the inclination becomes a detection error due to the dark current. Therefore, in the present embodiment, the detection error due to the dark current of the PSD is corrected by the following equation (2).
pxn = αpx × Kps × (Vadinx−Vadinx0) (2)
[0081]
In the above equation (2), pxn represents the current position (um) in the X direction of the camera shake correction optical system 27, αpx represents a dark current correction coefficient for removing the influence of the dark current, and Kps represents Kps. , A moving amount conversion coefficient (um / bit), Vadinx represents an ADC value (bit) of the difference voltage ADIN corresponding to a PSD difference current, and Vadinx0 is an ADC value (bit) of the difference voltage ADIN at the time of initial adjustment. ).
[0082]
Next, a method of calculating the dark current correction coefficient αpx will be described. The dark current is the sum voltage VAND (= VI) when the IRED is turned off (IREDON = “L”). ₁ + VI ₂ ) Can be detected by monitoring. In the present embodiment, for example, it is designed so that the sum current value of the PSD 2 (uA) = 0.896 (V) (the value of VANDX-ICVREF), and ΔVANDX0 at the time of adjustment at normal temperature (25 ° C.) = Assuming that the dark current is 0 (uA) as the voltage value of VANDX0-ICVREF, the dark current correction coefficient αpx is calculated by calculating the dark current voltage ΔVANDX = VANDX-ICVREF in the actual operation, and the dark current correction coefficient The current position pxn is calculated by substituting αpx into the above equation (2).
[0083]
That is, as shown in the following equation (3), the reference dark current voltage ΔVandx0 at the time of the initial adjustment is calculated by subtracting the reference voltage Vicvref from the sum voltage Vandx0 corresponding to the sum current at the time of the initial adjustment, and is previously stored in the memory. Remember.
ΔVandx0 = Vandx0−Vicvref (3)
[0084]
Then, as shown in the following equation (4), the dark current voltage ΔVandx during the actual operation is calculated by subtracting the reference voltage Vicvref from the sum voltage Vandx corresponding to the sum current during the actual operation.
ΔVandx = Vandx−Vicvref (4)
[0085]
Then, as shown in the following equation (5), the difference dark current voltage Vdifandx is calculated by subtracting the reference dark current voltage ΔVandx0 during the initial adjustment from the sum voltage Vandx corresponding to the sum current during the actual operation.
Vdifandx = ΔVandx−ΔVandx0 (5)
[0086]
Here, when the difference dark current voltage Vdifbandx is equal to or less than a predetermined value, the correction based on the dark current is not performed. That is, when the differential dark current voltage Vdifbandx is smaller than 9 (bit) (890 (mV) × 3/100 (3%) × 3 (mV / bit)), the influence of the dark current is small, and the dark current correction coefficient αpx = 1 and no correction by dark current is performed. In the present embodiment, 9 (bit) to be compared with the differential dark current voltage Vdifbandx is a design numerical value, and a predetermined numerical value is used in consideration of the influence of the dark current.
[0087]
When the difference dark current voltage Vdifbandx is 9 (bit) or more, the difference dark current voltage Vdifbandx is set to 298 (bit) (890 (mV) / 3 (mV / bit) as shown in the following equation (6). ) Is added to 1 to calculate a dark current correction coefficient αpx. In the present embodiment, 298 (bit) for dividing the differential dark current voltage Vdifbandx is a design value, and a predetermined value is used in consideration of the influence of the dark current.
αpx = 1 + Vdifandx / 298 (6)
[0088]
Expressions (2) to (6) describe the case where the PSD dark current of the X-direction position sensor 23 that detects the position of the camera shake correction optical system 27 in the X direction is corrected. The same applies to the case where the dark current of the PSD of the Y-direction position sensor 21 for detecting the position of the camera shake correction optical system 27 in the Y-direction is corrected. That is, the current position py in the Y direction of the camera shake correction optical system 27 can be obtained by the following equation (7), and the PSD of the PSD provided in the Y direction position sensor 21 that detects the position of the camera shake correction optical system 27 in the Y direction is obtained. Αpy for correcting the dark current can be obtained by the following equation (8).
pyn = αpy × Kps × (Vadiny−Vadiny0) (7)
αpy = 1 + Vdifandy / 298 (8)
[0089]
Next, the operation of the control circuit at the time of the initial adjustment will be described. FIG. 9 is a flowchart illustrating a process of the control circuit at the time of the initial adjustment. In addition, the following process is a process performed under normal temperature, and the normal temperature in this embodiment is 25 degreeC, for example.
[0090]
In step S1, the control circuit 18 outputs an L-level signal IREDON to the switch SW2 that switches on / off the IREDs 231 and 211, and turns off the IREDs 231 and 211. The IRED 211 is an IRED included in the Y-direction position sensor 21.
[0091]
In step S2, the control circuit 18 outputs an H level signal PWRON to the switch SW1 for switching on / off the circuit power of the PSD signal processing circuits 233 and 213, and turns on the circuit power. The PSD signal processing circuit 213 is a PSD signal processing circuit included in the Y-direction position sensor 21.
[0092]
In step S3, the control circuit 18 is in a standby state for a time until the power supply voltage is applied to each of the PSD signal processing circuits 233 and 213 and the circuits are stabilized. In the present embodiment, the stabilization time during which the PSD signal processing circuit 233 stabilizes is set to, for example, 10 msec.
[0093]
In step S4, the control circuit 18 waits for 1 msec in consideration of a loop in step S7 described later.
[0094]
In step S5, the control circuit 18 performs A / D conversion of the reference voltage value ICVREF of the PSD signal processing circuits 233 and 213, and obtains the A / D converted reference voltage value ICVREF. Further, the control circuit 18 controls the current I output from one electrode of the PSD 232 in the X-direction position sensor 23 for detecting the position of the camera shake correction optical system 27 in the X-direction. ₁ And the current I output from the other electrode ₂ A / D-converts the sum voltage VANDX corresponding to the sum current with the sum to obtain the A / D-converted sum voltage VANDX.
[0095]
In step S6, the control circuit 18 controls the current I outputted from one of the electrodes of the PSD in the Y-direction position sensor 21 for detecting the position of the camera shake correction optical system 27 in the Y-direction. ₁ And the current I output from the other electrode ₂ A / D-converts the sum voltage VANDY corresponding to the sum current of the sum and obtains the A / D-converted sum voltage VANDY.
[0096]
In step S7, the control circuit 18 determines whether or not the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY have been detected the number of times that the noise due to the dark current can be sufficiently removed. That is, in the present embodiment, the detection error is eliminated by detecting and averaging the reference voltage value ICVREF, the sum voltage VANDX, and the sum voltage VANDY a plurality of times, respectively, thereby improving accuracy. In the present embodiment, the number of times that noise due to dark current can be sufficiently removed is, for example, 16 times, and the processes in steps S4 to S6 are performed 16 times. However, the present invention is not particularly limited to this. Instead, for example, the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY may be detected only once, or may be detected 16 times or more and averaged. Here, when the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY are detected by the number of times that the noise due to the dark current can be sufficiently removed (YES in step S7), the process proceeds to step S8, and the dark current is detected. If the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY have not been detected by the number of times that the noise due to the noise can be sufficiently removed (NO in step S7), the process returns to step S4.
[0097]
In step S8, the control circuit 18 calculates the average value of the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY detected the number of times that the noise due to the dark current can be sufficiently removed. That is, the control circuit 18 calculates the average value of the reference voltage value ICVREF, the sum voltage VANDX, and the sum voltage VANDY for 16 times, respectively. When the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY are detected only once, the processes in steps S4, S7, and S8 are not required, and the processes can be simplified.
[0098]
In step S9, the control circuit 18 stores the average reference voltage value AVE_ICVREF, which is the average value of the 16 reference voltage values ICVREF, in the memory (EEPROM) as the initial reference voltage value Vicvref0, and stores the average value of the 16 sum voltage VANDX. Is stored in the memory (EEPROM) as the initial sum voltage Vandx0, and the average sum voltage AVE_VANDY, which is the average value of 16 times of the sum voltage VANDY, is stored in the memory (EEPROM) as the initial sum voltage Vand0.
[0099]
As described above, when the camera 1 is shipped, the above-described initial adjustment processing is performed, and the reference voltage value and the voltage value of the sum current in the X and Y directions which are not affected by the dark current at normal temperature (25 ° C.) are respectively set in advance. Store it in memory.
[0100]
FIG. 10 is a flowchart illustrating a dark current removal process for removing a dark current during camera shake correction. The dark current removal processing shown in FIG. 10 is processing performed by the control circuit 18.
[0101]
In step S11, the control circuit 18 outputs an H-level signal PWRON to the switch SW1 that switches on / off the circuit power of the PSD signal processing circuits 233 and 213, and turns on the circuit power.
[0102]
In step S12, the control circuit 18 outputs an L-level signal IREDON to the switch SW2 that switches on / off the IREDs 231 and 211, and turns off the IRED 231.
[0103]
In step S13, the control circuit 18 detects a sum voltage value VANDX corresponding to the sum current of the PSD 232 of the X-direction position sensor 23 and a sum voltage value VANDY corresponding to the sum current of the PSD 212 of the Y-direction position sensor 21. The sum voltage value detection processing for detecting the sum voltage values VANDX and VANDY in step S13 will be described later with reference to FIG.
[0104]
In step S14, the control circuit 18 calculates a sum voltage value VANDX corresponding to the sum current of the PSD 232 of the X-direction position sensor 23 and a sum voltage value VANDY corresponding to the sum current of the PSD 212 of the Y-direction position sensor 21 detected in step S13. And an initial reference voltage value Vicvref0 detected during the initial adjustment, a sum voltage value Vandx0 corresponding to the sum current of the PSD of the X-direction position sensor 23, and a sum voltage value Vandy0 corresponding to the sum current of the PSD of the Y-direction position sensor 21. The dark current correction coefficient is calculated based on the above. The dark current correction coefficient calculation processing for calculating the dark current correction coefficient in step S14 will be described later with reference to FIG.
[0105]
In step S15, the control circuit 18 waits for a time during which the angular velocity signals output from the P shake detection gyro 11 and the Ya shake detection gyro 12 are stabilized.
[0106]
FIG. 11 is a flowchart showing the sum voltage value detection processing for detecting the sum voltage values VANDX and VANDY in step S13 of FIG. Note that the sum voltage values VANDX, VANDY detection processing shown in FIG. 11 is processing performed by the control circuit 18.
[0107]
In step S21, the control circuit 18 is in a standby state until the power supply voltage is applied to each circuit of the PSD signal processing circuit 233 and the circuit is stabilized. In the present embodiment, the stabilization time during which the PSD signal processing circuit 233 stabilizes is set to, for example, 10 msec.
[0108]
In step S22, the control circuit 18 waits for 1 msec in consideration of a loop in step S25 described later.
[0109]
In step S23, the control circuit 18 performs A / D conversion of the reference voltage value ICVREF of the PSD signal processing circuits 233 and 213, and acquires the A / D converted reference voltage value ICVREF. Further, the control circuit 18 controls the current I output from one electrode of the PSD 232 in the X-direction position sensor 23 for detecting the position of the camera shake correction optical system 27 in the X-direction. ₁ And the current I output from the other electrode ₂ A / D-converts the sum voltage VANDX corresponding to the sum current with the sum to obtain the A / D-converted sum voltage VANDX.
[0110]
In step S24, the control circuit 18 determines the current I output from one of the electrodes of the PSD in the Y-direction position sensor 21 that detects the position of the camera shake correction optical system 27 in the Y-direction. ₁ And the current I output from the other electrode ₂ A / D-converts the sum voltage VANDY corresponding to the sum current of the sum and obtains the A / D-converted sum voltage VANDY.
[0111]
In step S25, the control circuit 18 determines whether or not the reference voltage value ICVREF, the sum voltage VANDX, and the sum voltage VANDY have been detected by the number of times that the noise due to the dark current can be sufficiently removed. That is, in this embodiment, the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY are each detected and averaged a plurality of times, thereby eliminating detection errors and improving accuracy. In the present embodiment, the number of times that noise due to dark current can be sufficiently removed is, for example, 16 times, and the processes in steps S22 to S24 are performed 16 times. However, the present invention is not particularly limited to this. However, for example, the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY may be detected only once, or may be detected 16 times or more and averaged. Here, when the reference voltage value ICVREF, the sum voltage VANDX, and the sum voltage VANDY are detected by the number of times that the noise due to the dark current can be sufficiently removed (YES in Step S25), the process proceeds to Step S26, and the dark current is detected. If the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY have not been detected the number of times that the noise due to the noise can be sufficiently removed (NO in step S25), the process returns to step S22.
[0112]
In step S26, the control circuit 18 calculates the average value of the reference voltage ICVREF, the sum voltage VANDX, and the sum voltage VANDY detected the number of times that the noise due to the dark current can be sufficiently removed. That is, the control circuit 18 calculates the average value of the reference voltage value ICVREF, the sum voltage VANDX, and the sum voltage VANDY for 16 times, respectively. When the reference voltage value ICVREF, the sum voltage VANDX, and the sum voltage VANDY are detected only once, the processes of Step S22, Step S25, and Step S26 become unnecessary, and the process can be simplified.
[0113]
In step S27, the control circuit 18 sets the average value of the 16 reference voltage values ICVREF to the average reference voltage value AVE_ICVREF, sets the average value of the 16 sum voltage VANDX to the average sum voltage AVE_VANDX, and sets the average value of the sum voltage VANDY to 16 times. The average value is temporarily stored in a memory as an average sum voltage AVE_VANDY.
[0114]
FIG. 12 is a flowchart showing the dark current correction coefficient calculation processing for calculating the dark current correction coefficient in step S14 of FIG. The dark current correction coefficient calculation process shown in FIG. 12 is a process performed by the control circuit 18.
[0115]
In step S31, the control circuit 18 includes a dark current correction coefficient αpx for correcting the PSD dark current of the X-direction position sensor 23 and a dark current correction coefficient αpy for correcting the PSD dark current of the Y-direction position sensor 21. Are both set to 1.
[0116]
In step S32, the control circuit 18 calculates the reference dark current voltage ΔVandx0 by subtracting the initial reference voltage Vicvref0 from the initial sum voltage Vandx0 stored in the memory. Further, the control circuit 18 calculates the reference dark current voltage ΔVandy0 by subtracting the initial reference voltage Vicvref0 from the initial sum voltage Vandy0 stored in the memory.
[0117]
In step S33, the control circuit 18 calculates the dark current voltage ΔVandx by subtracting the average reference voltage value AVE_ICVREF from the average sum voltage AVE_VANDX calculated in step S27. Further, the control circuit 18 calculates the dark current voltage ΔVandy by subtracting the average reference voltage value AVE_ICVREF from the average sum voltage AVE_VANDY calculated in step S27.
[0118]
In step S34, the control circuit 18 calculates a differential dark current voltage Vdifandx by subtracting the reference dark current voltage ΔVandx0 calculated in step S32 from the dark current voltage ΔVandx calculated in step S33. Further, the control circuit 18 calculates the difference dark current voltage Vdifandy by subtracting the reference dark current voltage ΔVandy0 calculated in step S32 from the dark current voltage ΔVandy calculated in step S33.
[0119]
In step S35, the control circuit 18 determines whether or not the differential dark current voltage Vdifbandx calculated in step S34 is 9 bits or more. Here, if the difference dark current voltage Vdifbandx is 9 bits or more (YES in step S35), the process proceeds to step S36 to correct the dark current, and if the difference dark current voltage Vdifbandx is smaller than 9 bits (step S35). NO), the X-direction position sensor 23 is less affected by the dark current, and there is no need to correct the dark current, so the flow proceeds to step S37.
[0120]
In step S36, the control circuit 18 sets the dark current correction coefficient αpx set to αpx = 1 in step S31 to αpx = 1 + Vdifandx / 298. If it is determined in step S35 that the difference dark current voltage Vdifbandx is smaller than 9 bits, the dark current correction coefficient αpx remains αpx = 1, and no dark current correction is performed.
[0121]
In step S37, the control circuit 18 determines whether the differential dark current voltage Vdifvandy calculated in step S34 is 9 bits or more. Here, if the difference dark current voltage Vdifvandy is 9 bits or more (YES in step S37), the process proceeds to step S38 to correct the dark current, and if the difference dark current voltage Vdifvandy is smaller than 9 bits (step S37). NO), the X-direction position sensor 23 returns because the influence of the dark current is small and there is no need to correct the dark current.
[0122]
In step S38, the control circuit 18 sets the dark current correction coefficient αpy set to αpy = 1 in step S31 to αpy = 1 + Vdifandy / 298. If it is determined in step S37 that the difference dark current voltage Vdifvandy is smaller than 9 bits, the dark current correction coefficient αpy remains at αpy = 1, and no dark current correction is performed.
[0123]
As described above, light is emitted by the IREDs 231 and 211 of the X and Y direction position sensors 23 and 21, and light from the IREDs 231 and 211 is received by the PSDs 232 and 212 of the X and Y direction sensors 23 and 21. A photocurrent corresponding to the light receiving position is output, and the light source current control unit 44 detects the sum current of the photocurrents output from the PSDs 232 and 212 and controls the light amounts of the IREDs 231 and 211.
Then, with the IREDs 231 and 211 turned off, sum voltages VANDX and VANDY corresponding to the sum of photocurrents output from the PSDs 232 and 212 are detected. The correction coefficient calculation unit 51 calculates dark current voltages ΔVandx and ΔVandy by subtracting the reference voltage Vicvref from the sum voltages VANDX and VANDY. Further, the correction coefficient calculation unit 51 subtracts the reference dark current voltages ΔVandx0, ΔVandy0 obtained by subtracting the reference voltage Vicvref from the reference sum voltages VANDX0, VANDY0 detected at the time of the initial adjustment from the dark current voltages ΔVandx, ΔVandy. Current voltages Vdifandx and Vdifandy are calculated. The correction coefficients αpx and αpy are calculated by the correction coefficient calculation unit 51 based on the difference dark current voltages Vdifbandx and Vdifbandy. The unit conversion circuit 187 detects voltages Vadinx and Vadiny corresponding to the difference current from the PSDs 232 and 212, and calculates the voltages Vadinx and Vadiny corresponding to the difference current based on the correction coefficients αpx and αpy calculated by the correction coefficient calculation unit 51. Converted to position data.
[0124]
Therefore, with the IREDs 231 and 211 turned off, the sum current of the photocurrents output from the PSDs 232 and 212 is detected as a dark current, and is included in the photocurrents output from the PSDs 232 and 212 based on the detected dark current. The correction coefficients αpx and αpy for removing the dark current are calculated, and are converted into position data by multiplying the difference current between the photocurrents output from the PSDs 232 and 212 by the correction coefficients αpx and αpy. , 212 can be easily and simply corrected.
[0125]
The process of calculating the dark current correction coefficient shown in FIG. 12 is performed at a predetermined timing according to the occurrence of the dark current. That is, the camera 1 according to the present embodiment includes a timer that measures an elapsed time from when the power is turned on, and the process of calculating the dark current correction coefficient illustrated in FIG. 12 is performed once a minute, for example. Is The timing for calculating the dark current correction coefficient is not particularly limited to the above, and may be, for example, once per second. Thus, the correction coefficient is calculated from the dark current detected at a predetermined timing. Therefore, a dark current generated under the influence of temperature rise due to aging is detected at a predetermined timing, and a correction coefficient is calculated from the dark current detected at the predetermined timing. The dark current of the PSD can be corrected.
[0126]
Further, the dark current is generated due to a change in the temperature of the PSD, and the temperature of the PSD increases with the lapse of time from when the power is turned on. Thus, the time during which the dark current of the PSD is generated is stored in the memory in advance, and when the time measured by the timer reaches the time stored in the memory, the process of correcting the dark current may be performed. .
In this way, the timer measures the elapsed time from when the power is turned on, and when the elapsed time measured by the timer reaches a predetermined time during which the dark current occurs, correction is performed from the detected dark current. A coefficient is calculated. Therefore, when the temperature of the PSD is low immediately after the power is turned on, the amount of generation of the dark current is small. Therefore, the process of calculating the correction coefficient from the detected dark current is not performed, and the elapsed time since the power is turned on is the dark current When the predetermined time occurs, the process of calculating the correction coefficient from the detected dark current is performed, so that the load on the process for correcting the dark current can be reduced.
[0127]
Further, the dark current tends to increase at high temperatures. Therefore, the temperature at which the dark current of the PSD is generated is stored in the memory in advance, and the temperature of the PSD is measured by the temperature sensor 26. When the measured temperature of the PSD becomes higher than the temperature stored in the memory, A process for correcting the dark current may be performed. That is, for example, when the temperature of the PSD becomes 60 ° C. or higher, a process of correcting the dark current is performed. As described above, the temperature of the PSD is measured by the temperature sensor 26, and when the temperature measured by the temperature sensor 26 reaches a predetermined temperature at which a dark current occurs, a correction coefficient is calculated from the detected dark current. Is done. Therefore, when the temperature of the PSD is low immediately after the power is turned on, the amount of generation of the dark current is small. Is reached, the process of calculating the correction coefficient from the detected dark current is performed, so that the load on the process for correcting the dark current can be reduced.
[0128]
Next, FIG. 13 shows an embodiment of the drive circuit 25.
[0129]
FIG. 13 is a circuit diagram showing one embodiment of the drive circuit. FIG. 14 is a circuit control state diagram showing the relationship between the N-channel H-bridge circuit and the voltage applied to the electromechanical transducer. FIG. 14A shows the relationship between the voltage value applied to the control terminals IN1, IN2, and INC and the direction of the voltage applied to the electromechanical transducer, and FIGS. 14B to 14D show the H-bridge circuit. The relationship between the ON / OFF state of each switch element and the moving direction of the moving member is shown. FIG. 15A shows a voltage value Vpx (Vp for X-direction driving) applied to the X-direction driving actuator, and FIG. 15B shows a PWM pulse Xpwm for driving the X-direction driving actuator. FIG. 3 is a diagram illustrating a relationship between an applied voltage applied to an electromechanical transducer and an applied voltage. FIGS. 15B and 15A show a voltage value Vpx applied to the X-direction drive actuator, and FIGS. 15B and 15B show PWM pulses Xpwm for driving the X-direction drive actuator. 15 (B) and (c) show applied voltages actually applied to the electromechanical transducer.
[0130]
In FIG. 13, the driver circuit 90 includes two H-bridge circuits 96 and 99 for two channels (ch), and one channel of the driver circuit 90 has an N-channel switch element as shown in FIG. This is a circuit of a MOS FET. The driving direction F / R of the H-bridge circuit 96 is controlled by the H level / L level of Xpwm input to the control terminal IN1 of the driver circuit 90, and the H-bridge circuit 99 is input to the control terminal IN2 of the driver circuit 90. The driving direction F / R is controlled by the H level / L level of Ypwm. Here, F indicates Forward, that is, the forward direction, and R indicates Reverse, that is, the reverse direction.
[0131]
Then, by setting the control terminal INC of the driver circuit 90 to L level, the applied voltage can be turned off. The control terminal PS of the driver circuit 90 is connected to a power save control terminal of a microcomputer (hereinafter abbreviated as “microcomputer”) 101, and turns off the circuit at a timing when camera shake correction is not used.
[0132]
Further, the driver circuit 90 has a function block (steps) for boosting the voltage of the control terminal of the MOS type FET and performing a level shift so that on / off of the N-channel MOS type FETs of the H bridge circuits 96 and 99 can be controlled. SW control function block (switch) for controlling ON / OFF of the MOS FET from output signals of the oscillation circuit 91, the charge pump circuit 92, the level control circuit 94, the level shift circuit 98, etc. and the control terminals IN1, IN2, INC. Circuit 95 and a control circuit 97), the voltage applied from the microcomputer 101 is low and the number of terminals for control signals is small. It is configured to be controllable.
[0133]
The driver circuit 90 has a built-in band gap reference circuit 93 for supplying a reference voltage to the oscillation circuit 91, the charge pump circuit 92, the level control circuit 94, and the control circuit 97.
[0134]
With respect to the driver circuit 90, voltages actually applied to the electromechanical transducer of the X-direction drive actuator 24 and the electromechanical transducer of the Y-direction drive actuator 22 are externally supplied as Vpx and Vpy, respectively. The control method is such that the voltage values CVpx and CVpy that are separately supplied for the Xch and Ych from the DACA 70 and DACB 80 which are the D / A conversion units of the microcomputer 101 are supplied to the differential amplifiers 72 to 81 via the buffer circuits 71 and 81. At 74, 82 to 84, the level shift and the amplification factor conversion are performed, and the applied voltages become the optimum applied voltages. Supplied respectively. The power supply voltage Vpi is supplied from a battery or a DC / DC converter as a constant value depending on the capacity (magnitude) of the electromechanical transducer used in the X-direction drive actuator 24 and the Y-direction drive actuator 22. In a case where a camera lens is driven, the power supply voltage Vpi is preferably about 6 V to 8 V. The capacitors 75 and 85 are charge storage capacitors for preventing the applied voltage from largely changing even when a high-frequency square wave voltage of about 60 kHz is applied to the electromechanical transducer. In the case of the present embodiment, it is preferably about 1 μF in consideration of the change cycle (for example, 1 kHz) of the applied voltage controlled by the microcomputer 101, the maximum voltage change amount, and the capacity of the electromechanical transducer.
[0135]
On the other hand, in FIG. 15A, when the applied voltage control value is fixed at Vpx, the driving direction F / H of the H bridge circuit 96 responds to the H level (Vcc) / L level (GND) of the control terminal IN1. Since R changes, the actual voltage applied to the electromechanical transducer changes as Vpx / −Vpx.
[0136]
FIG. 15 (B) also shows a change in Vpx with a coarser time resolution. For the direction inversion control of the H-bridge circuit 96 of about 60 kHz, the applied voltage is changed at about 1 kHz (the optimal applied voltage is updated) to control the actual applied voltage to the electromechanical transducer. By this control, the average speed of the electromechanical transducer can be controlled at 1 kHz cycle while always resonating at the optimum resonance frequency (for example, about 60 kHz). This control is repeatedly performed while the camera shake correction optical system 27 is being driven.
[0137]
In the present embodiment, the control circuit 18 for controlling the Y-direction drive actuator 22 and the X-direction drive actuator 24 is provided in the camera body 2, but the control circuit 18 may be provided on the photographic lens 3 side. Thereby, since each circuit for controlling the camera shake correction optical system 27 can be eliminated from the camera main body 2, the camera main body 2 can be further reduced in size and cost.
[0138]
The specific embodiments described above mainly include inventions having the following configurations.
[0139]
(1) a light emitting unit that emits light;
A light receiving unit that receives light from the light emitting unit and outputs a current according to a light receiving position on a light receiving surface;
In a state where the light emitting unit is turned off, a dark current detecting unit that detects a current output from the light receiving unit as a dark current,
Based on the dark current detected by the dark current detection unit, a correction coefficient calculation unit that calculates a correction coefficient for removing a dark current included in the current output from the light receiving unit,
A position data conversion unit that detects a difference current from the light receiving unit and converts the difference current into position data using a correction coefficient calculated by the correction coefficient calculation unit.
[0140]
(2) The position detection device according to (1), wherein the correction coefficient calculation unit calculates the correction coefficient from a dark current detected by the dark current detection unit at a predetermined timing.
[0141]
(3) further comprising a measuring unit for measuring an elapsed time since the power is turned on,
When the elapsed time measured by the measurement unit reaches a predetermined time, the correction coefficient calculation unit calculates the correction coefficient from the dark current detected by the dark current detection unit. The position detecting device according to the above (2).
[0142]
(4) further comprising a temperature detecting section for detecting a temperature of the light receiving section;
When the temperature detected by the temperature detecting section reaches a predetermined temperature, the correction coefficient calculating section calculates the correction coefficient from the dark current detected by the dark current detecting section. The position detecting device according to the above (1).
[0143]
(5) emitting light from the light emitting unit;
In a state where the light emitting unit is turned off, a step of detecting as a dark current a current output from the light receiving unit that receives light from the light emitting unit and outputs a current corresponding to a light receiving position on a light receiving surface,
Based on the detected dark current, a step of calculating a correction coefficient for removing the dark current included in the current output from the light receiving unit,
Detecting a difference current from the light receiving unit and converting the difference current into position data using the correction coefficient.
[0144]
(6) In an imaging apparatus including a camera shake correction optical system for correcting camera shake,
An actuator for driving the optical system for camera shake correction,
A position detection unit that detects a current position of the camera shake correction optical system,
A calculation unit for calculating a control target position of the camera shake correction optical system,
A drive control unit that controls the drive of the actuator according to a difference between the current position and the control target position, so that the camera shake correction optical system follows the control target position,
A light emitting unit that emits light,
A light receiving unit that receives light from the light emitting unit and outputs a current according to a light receiving position on a light receiving surface;
In a state where the light emitting unit is turned off, a dark current detecting unit that detects a current output from the light receiving unit as a dark current,
Based on the dark current detected by the dark current detection unit, a correction coefficient calculation unit that calculates a correction coefficient for removing a dark current included in the current output from the light receiving unit,
A conversion unit that detects a difference current from the light receiving unit and converts the difference current into a current position of the optical system for camera shake correction using a correction coefficient calculated by the correction coefficient calculation unit. apparatus.
[0145]
【The invention's effect】
According to the first aspect of the present invention, with the light emitting unit turned off, the current output from the light receiving unit is detected as a dark current, and the current output from the light receiving unit is determined based on the detected dark current. A correction coefficient for removing the included dark current is calculated, and the difference current is converted into position data by multiplying the difference current of the current output from the light receiving section by the correction coefficient. Can be easily corrected with high performance.
[0146]
According to the second aspect of the present invention, the correction coefficient for removing the dark current included in the current output from the light receiving unit is calculated based on the dark current detected by the dark current detecting unit at a predetermined timing. Is done. Therefore, a dark current generated under the influence of temperature rise due to aging is detected at a predetermined timing, and a correction coefficient for removing the dark current is calculated based on the dark current detected at the predetermined timing. Therefore, the dark current of the light receiving unit can be corrected in real time according to the temperature rise.
[0147]
According to the third aspect of the invention, since the amount of dark current generated is small when the temperature of the light receiving unit is low immediately after the power is turned on, the process of calculating the correction coefficient from the dark current detected by the dark current detecting unit is performed. When the elapsed time from when the power is turned on reaches a predetermined time, the dark current included in the current output from the light receiving unit is removed based on the dark current detected by the dark current detecting unit. Since the processing for calculating the correction coefficient for performing the correction is performed, the load on the processing for correcting the dark current can be reduced.
[0148]
According to the invention as set forth in claim 4, in a state where the light emitting unit is turned off, the current output from the light receiving unit is detected as a dark current, and the current output from the light receiving unit is determined based on the detected dark current. A correction coefficient for removing the included dark current is calculated, and the difference current is converted into position data by multiplying the difference current of the current output from the light receiving section by the correction coefficient. Can be easily corrected with high performance.
[0149]
According to the fifth aspect of the present invention, in a state where the light emitting unit is turned off, the current output from the light receiving unit is detected as a dark current, and the current output from the light receiving unit is determined based on the detected dark current. A correction coefficient for removing the included dark current is calculated, and the difference current is converted to the current position of the optical system for camera shake correction by multiplying the difference current of the current output from the light receiving unit by the correction coefficient. In addition, the correction of the dark current of the light receiving section can be performed easily and with high performance, and the dark current of the light receiving section is corrected, so that a highly accurate camera shake correction can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically illustrating a configuration of a camera with a camera shake correction function according to an embodiment.
FIG. 2 is a diagram schematically showing a configuration of a camera shake correction optical system unit.
FIG. 3 is a block diagram showing a configuration of a control circuit and its peripheral circuits.
FIG. 4 is a diagram illustrating an example of a characteristic that is formed into a lookup table used in the LU table circuit.
FIG. 5 is a diagram showing a specific configuration of an X-direction position sensor.
6 is a block diagram showing a configuration of a PSD signal processing circuit shown in FIG. 3 and its peripheral circuits.
FIG. 7 is a diagram illustrating an example of a specific circuit configuration of a PSD signal processing circuit.
FIG. 8 is a diagram for describing a dark current of the PSD.
FIG. 9 is a flowchart illustrating processing of a control circuit at the time of initial adjustment.
FIG. 10 is a flowchart illustrating a dark current removal process for removing a dark current during camera shake correction.
11 is a flowchart showing a sum voltage value detection process for detecting sum voltage values VANDX and VANDY in step S13 in FIG.
FIG. 12 is a flowchart showing a dark current correction coefficient calculation process for calculating a dark current correction coefficient in step S14 of FIG.
FIG. 13 is a circuit diagram showing one embodiment of a drive circuit.
FIG. 14 is a circuit control state diagram showing a relationship between an N-channel H-bridge circuit and an applied voltage of an electromechanical transducer.
FIG. 15 shows a voltage value Vpx (Vp for X-direction drive) applied to the X-direction drive actuator, a PWM pulse Xpwm for driving the X-direction drive actuator, and an applied voltage actually applied to the electromechanical transducer. It is a figure showing a relation.
[Explanation of symbols]
11 P runout detection gyro
12 Ya shake detection gyro
13 Shake detection circuit
14 Runout detection circuit
15 Coefficient conversion circuit
16 Release button
17 Sequence control circuit
18 Control circuit
21 Y-direction position sensor
22 Y direction drive actuator
23 X direction position sensor
24 X direction drive actuator
25 Drive circuit
26 Temperature sensor
27 Camera shake correction optical system
28 Shooting Optical System
41, 42 current / voltage conversion circuit
43 Addition circuit
44 Light source current controller
45 Subtraction circuit
46 Amplification LPF circuit
51 Correction coefficient calculator
187 Unit conversion circuit
231 IRED
232 PSD

Claims (5)

A light emitting unit that emits light,
A light receiving unit that receives light from the light emitting unit and outputs a current according to a light receiving position on a light receiving surface;
In a state where the light emitting unit is turned off, a dark current detecting unit that detects a current output from the light receiving unit as a dark current,
Based on the dark current detected by the dark current detection unit, a correction coefficient calculation unit that calculates a correction coefficient for removing a dark current included in the current output from the light receiving unit,
A position data conversion unit that detects a difference current from the light receiving unit and converts the difference current into position data using a correction coefficient calculated by the correction coefficient calculation unit. The position detecting device according to claim 1, wherein the correction coefficient calculation unit calculates the correction coefficient from a dark current detected by the dark current detection unit at a predetermined timing. It further includes a measuring unit that measures the elapsed time since the power was turned on,
When the elapsed time measured by the measurement unit reaches a predetermined time, the correction coefficient calculation unit calculates the correction coefficient from the dark current detected by the dark current detection unit. The position detecting device according to claim 2. Emitting light from the light emitting unit;
In a state where the light emitting unit is turned off, a step of detecting as a dark current a current output from the light receiving unit that receives light from the light emitting unit and outputs a current corresponding to a light receiving position on a light receiving surface,
Based on the detected dark current, a step of calculating a correction coefficient for removing the dark current included in the current output from the light receiving unit,
Detecting a difference current from the light receiving unit and converting the difference current into position data using the correction coefficient. In an imaging apparatus including a camera shake correction optical system for correcting camera shake,
An actuator for driving the optical system for camera shake correction,
A position detection unit that detects a current position of the camera shake correction optical system,
A calculation unit for calculating a control target position of the camera shake correction optical system,
A drive control unit that controls the drive of the actuator according to a difference between the current position and the control target position, so that the camera shake correction optical system follows the control target position,
A light emitting unit that emits light,
A light receiving unit that receives light from the light emitting unit and outputs a current according to a light receiving position on a light receiving surface;
In a state where the light emitting unit is turned off, a dark current detecting unit that detects a current output from the light receiving unit as a dark current,
Based on the dark current detected by the dark current detection unit, a correction coefficient calculation unit that calculates a correction coefficient for removing a dark current included in the current output from the light receiving unit,
A conversion unit that detects a difference current from the light receiving unit and converts the difference current into a current position of the optical system for camera shake correction using a correction coefficient calculated by the correction coefficient calculation unit. apparatus.

Images