JP2018033070A - Signal processing apparatus for acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect camera shake with high accuracy by using an acceleration sensor.SOLUTION: A signal processing apparatus amplifies a signal from an acceleration sensor 14 with a first amplifier AMP 1, converts an output from the first amplifier AMP 1 into a digital signal with a first AC converter ADC 1 and inputs the digital signal to an arithmetic part 22 for camera shake correction, inputs the output from the first amplifier AMP 1 to a second amplifier AMP 2, converts the output into a digital signal with a second AD converter ADC 2 and inputs the digital signal to the arithmetic part 22 for camera shake correction, sets a reference voltage Vref2 of the second amplifier AMP 2 on the basis of a value from the first AD converter ADC 1, and performs translation shake correction on the basis of a value from the second AD converter ADC 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a signal processing apparatus for processing a signal from an acceleration sensor used for camera shake detection.

  Many digital cameras have a camera shake correction function that is digitally controlled. The basis of camera shake correction processing is to detect fluctuations in the pitch angle (around the X axis) and yaw angle (around the Y axis) of the camera body with an angular velocity sensor and cancel image blur based on the signals from both sensors converted into digital signals. Camera shake is corrected by moving the correction lens or image sensor in the direction (biaxial correction). In digital signal processing, in order to detect the output from the sensor with high accuracy, it is necessary to match the output from the sensor to the dynamic range of the AD converter. In a camera shake correction device, a configuration is known in which a signal from a position detecting Hall element is amplified in accordance with a dynamic range of an AD converter in order to obtain position information of a movable part necessary for camera shake correction with high accuracy. (See Patent Document 1).

  On the other hand, in recent years, in order to perform camera shake correction more precisely in accordance with various forms of camera shake, in addition to the basic biaxial correction, a change in the roll angle (around the Z axis) is detected by an angular velocity sensor, and X 3-axis correction that corrects rotational fluctuations around all axes, Y-axis, and Z-axis, and 4-axis correction that adds translational fluctuation correction in the X-axis direction and Y-axis direction to the basic 2-axis correction, X 5-axis correction has also been proposed in which rotational fluctuations around the axes, Y-axis, and Z-axis and translational fluctuations in the X-axis direction and Y-axis direction are corrected. An angular velocity sensor is used to detect rotational fluctuations (rotational shake) of the pitch angle, yaw angle, and roll angle, and an acceleration sensor is used to detect translational fluctuations (translational shake) in the X-axis, Y-axis, and Z-axis directions. used.

Japanese Patent Laying-Open No. 2015-169928

  However, since the acceleration sensor for translational shake detection also detects gravitational acceleration, the reference voltage changes depending on the posture of the camera. For this reason, in the configuration in which the sensor signal is simply amplified as in Patent Document 1, the output from the sensor cannot be adapted to the dynamic range of the AD converter.

  More specifically, the translational shake often includes a slower or smaller fluctuation than the rotational shake. For example, detection of a signal with an acceleration of 1 mG or less is desired. However, when an acceleration sensor with a sensitivity of ± 2 G is used and a signal from the acceleration sensor is read by a 12-bit AD converter, the acceleration 1 mG is 1 LSB or less of the AD converter and cannot be detected. In order to detect a signal of 1 mG or less, the signal from the sensor may be amplified. However, since the acceleration sensor also detects gravitational acceleration (about 1 G), the gravitational acceleration appears as an offset in the signal of the acceleration sensor. Therefore, 0 (zero) G in the signal of the acceleration sensor does not necessarily correspond to a state in which there is no translational shake, and the fluctuation center of the signal from the sensor varies in a range of about ± 1 G depending on the posture of the camera. Therefore, if the amplification factor is set in accordance with a signal with an acceleration of 1 mG or less, the output of the AD converter may be saturated.

  Although the offset of the DC component can be canceled through the high-pass filter, it is difficult to pass the translational shake through the high-pass filter because it is required to detect a slow fluctuation of several Hz. A solution to increase the resolution of the AD converter is also conceivable. Currently, products with a resolution of about 12 bits and a dynamic range of about 0 V to 3 V are often used as image stabilization AD converters. However, even if the resolution is made higher than this, the actual accuracy is not improved so much, and if the voltage per 1 LSB is lowered, it will be buried in the noise of the output signal of the sensor, and the increased resolution cannot be used effectively. Can be considered. In order to solve these problems, it is necessary not only to increase the resolution of the AD converter, but also to expand the dynamic range, and the high power supply voltage necessary for it is necessary. The effect that can be expected for the cost of increasing the component and board area is low.

  An object of the present invention is to detect an acceleration sensor signal with high accuracy.

  The signal processing apparatus according to the present invention includes a first amplifying unit that amplifies or offsets a sensor signal from the acceleration sensor, a second amplifying unit that amplifies the sensor signal or the signal from the first amplifying unit, and a first amplifying unit. Reference voltage setting means for setting the reference voltage of the second amplifying means based on the output of the second amplification means, and the amplification factor of the output of the second amplification means relative to the sensor signal is higher than the amplification factor of the output of the first amplification means relative to the sensor signal. It is characterized by high price.

  The reference voltage is set when the output from the first amplifying means satisfies a predetermined condition. The signal processing apparatus includes AD conversion means, and the outputs of the first amplification means and the second amplification means are converted into digital values by the AD conversion means. The AD conversion means may include a first AD converter that AD converts the output of the first amplification means, and a second AD converter that AD converts the output of the second amplification means. The AD conversion means includes switching means for switching input between the output from the first amplification means and the output from the second amplification means, and converts one of the outputs from the first or second amplification means into a digital value. The structure to do may be sufficient.

  For example, the reference voltage is set based on the digital value of the output of the first amplifying means. The signal processing apparatus includes DA conversion means, and the reference voltage of the second amplification means is output to the second amplification means via the DA conversion means.

  Voltage holding means for holding the output voltage of the first amplification means may be provided, and the reference voltage setting means may set the reference voltage to a voltage held in the voltage holding means. An amplifier may be shared by the second amplifying unit and the voltage holding unit. The first amplifying means may transmit the acceleration sensor signal at the same magnification.

  A camera shake correction apparatus according to the present invention is an image pickup apparatus including the signal processing device, and is characterized in that translational shake correction is performed based on an output of a second amplifying unit.

  The image pickup apparatus of the present invention is an image pickup apparatus including the above-described camera shake correction device, wherein the reference voltage setting unit does not change the setting of the reference voltage during the exposure period.

  According to the present invention, the signal of the acceleration sensor can be detected with high accuracy.

1 is a block diagram illustrating a configuration of a digital camera equipped with a camera shake correction device according to an embodiment of the present invention. It is a circuit diagram which shows the structure of the circuit part of 1st Embodiment. It is a graph which shows the timing of the setting of a reference voltage. It is a circuit diagram which shows the structure of the circuit part of 2nd Embodiment. It is a circuit diagram which shows the structure of the circuit part of 3rd Embodiment. It is a circuit diagram which shows the structure of the circuit part of 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an electrical configuration related to a camera shake correction mechanism of a digital camera (imaging device) equipped with the camera shake correction device according to the first embodiment of the present invention.

  The digital camera 10 includes an angular velocity sensor 12 and an acceleration sensor 14 for detecting camera shake. The angular velocity sensor 12 and the acceleration sensor 14 correspond to a plurality of axes including at least the X axis and the Y axis among the three orthogonal axes X (pitch axis), Y axis (yaw axis), and Z axis (roll axis) of the camera body. Rotational shake and translational shake are detected.

  Outputs from the angular velocity sensor 12 and the acceleration sensor 14 are respectively input to the amplifier / filter circuits 16 and 18 of the present embodiment, subjected to predetermined signal processing, and then input to an AD / DA converter (ADC) 20. It is converted into a digital signal (note that the amplifier and the filter may be incorporated in the package of the angular velocity sensor 12 and the acceleration sensor 14). The sensor signals of the angular velocity sensor 12 and the acceleration sensor 14 converted into digital signals are respectively input to a camera shake correction calculation unit 22 configured by a DSP or the like, and correction calculation for canceling camera shake is performed.

  In this embodiment, the camera shake correction device translates, for example, a lens frame of a correction lens (not shown) configured as a movable unit or an image sensor stage in the X axis direction and the Y axis direction, and further moves the image sensor stage to the Z axis. By rotating around, the rotational shake and translational shake that occur around the X, Y, and Z axes are canceled out. As is well known in the art, the camera shake correction calculation unit 22 is based on the sensor signals (shake signals) from the angular velocity sensor 12 and the acceleration sensor 14, the focal length, and the current position information (described later) of the movable unit. The translational movement amount of the movable part and the rotation amount of the movable part around the Z axis are calculated, and a drive signal is output to the actuator driver 24 of the camera shake correction device.

  The actuator driver 24 drives the movable part moving actuator 26 based on the drive signal. The camera shake correction apparatus includes a plurality of position detection sensors 28 for detecting the position of the movable part, and a signal corresponding to the position of the movable part moved by the movable part moving actuator 26 is output from the position detection sensor 28 to an amplifier / filter circuit. 30. Note that as many position detection sensors 28 as necessary for the control are provided according to the translational motion and the rotational motion of the movable part to be controlled.

  The sensor signal from the position detection sensor 28 that has been amplified by the amplifier / filter circuit 30 is input to the AD / DA converter 20 and converted into a digital signal, which is then input to the camera shake correction calculation unit 22 for detection. The obtained current position information of the movable part is used to calculate the next translational movement amount of the movable part in each axial direction and the next rotation amount of the movable part around the Z axis. This series of operations is repeated at a constant period during the camera shake correction operation. In the present embodiment, the same AD / DA converter 20 is used for AD conversion of sensor signals from the angular velocity sensor 12, the acceleration sensor 14, and the position detection sensor 28, and is switched by a switch or the like. An AD converter may be prepared. The camera shake correction calculation unit 22 is controlled by, for example, a camera main calculation unit 32 that performs overall control of the digital camera 10. A main memory 34 is connected to the camera main calculation unit 32.

  Next, a sensor signal amplification process in the first embodiment will be described with reference to FIG. FIG. 2 is a circuit diagram showing a circuit configuration of the amplifier / filter circuits 16 and 18 related to amplification of the sensor signal from the acceleration sensor 12 (a circuit portion corresponding to the filter is omitted).

  FIG. 2 shows a circuit configuration until an output from one uniaxial acceleration sensor arbitrarily selected from a plurality of acceleration sensors 14 is input to the camera shake correction calculation unit. A multi-axis acceleration sensor can be handled by providing a plurality of similar circuit configurations for each axis. However, the configuration of the amplifier circuit for the X-axis and Y-axis acceleration sensors may generally be the same, but it is often desirable to use a different configuration for the Z-axis because the method of use and the correction method are often different.

  Since the detection sensitivity of the acceleration sensor 14 should be sensitive, the detection range is, for example, about ± 2G. For this reason, the influence of gravitational acceleration (about 1 G) on the signal component of the acceleration sensor 14 is relatively large, and may not be within the dynamic range of AD conversion depending on the posture of the camera. Therefore, in the present embodiment, the amplification factor of the sensor signal can be changed according to the posture of the camera body, and the sensor signal is always within the dynamic range of AD conversion even when the highly sensitive acceleration sensor 14 is used. ing.

  The signal from the acceleration sensor 14 is amplified or offset adjusted by the first amplifier AMP1 of the amplifier circuit section 18A of the amplifier / filter circuit 18, and the output is output from the first AD converter ADC1 of the AD / DA converter 20 and the amplifier / filter circuit 18. The signal is input to the second amplifier AMP2 of the amplifier circuit unit 18A. The first amplification factor, which is the amplification factor of the first amplifier AMP1, is a low amplification factor or equal magnification.

  The first amplifier AMP1 is supplied with a predetermined first reference voltage Vref1 corresponding to zero fluctuation through a pull-down resistor, and a differential input of a sensor signal based on this is amplified with a first amplification factor and output. Output from the terminal. If the first amplifier AMP1 has the same magnification and no offset adjustment is required, the terminal of the acceleration sensor 14 may be directly connected to the input terminal of the first AD converter ADC1 or the second amplifier AMP2, or the first amplifier AMP1. May be configured as a voltage follower.

  A second reference voltage Vref2, which will be described later, is input to the second amplifier AMP2 via a pull-down resistor, and a differential input of a signal input from the first amplifier AMP1 with this as a reference is a second amplification factor (more than 1). Amplified with a large value). The signal output from the second amplifier AMP2 is input to the second AD converter ADC2 of the AD / DA converter 20, converted into a digital signal, and then input to the camera shake correction calculation unit 22.

  The second reference voltage Vref2 for the second amplifier AMP2 is changed based on an instruction from the camera shake correction calculation unit 22, and is supplied to the second amplifier AMP2 through the DA converter DAC of the AD / DA converter 20. That is, when the translational blur correction is set to ON in the camera and the camera is ready to shoot, the digital value of the sensor signal input via the first AD converter ADC1 is constantly monitored by the camera shake correction calculation unit 22. In the case where “the average value of the sampling value for the predetermined number of times in the first AD converter ADC1 is within the predetermined range for the predetermined time or continuously for the predetermined number of times”, the voltage or the average value at that time is periodically Is set to the second reference voltage Vref2. If the value of the first AD converter ADC1 or the second AD converter ADC2 fluctuates beyond a predetermined value while the output of the first AD converter ADC1 is being monitored, the setting value of the second reference voltage Vref2 is temporarily changed. When the above condition, that is, the condition that “the average value of the sampling values for the predetermined number of times in the first AD converter ADC1 falls within a predetermined range for a predetermined time or continuously for a predetermined number of times” is satisfied, 2 The set value of the reference voltage Vref2 is updated.

  When the user is moving with the camera or trying various angles, the acceleration changes greatly, and the signal output from the acceleration sensor 14 also changes greatly. On the other hand, when the angle is determined and the camera is held in a fixed posture and the state is maintained, the signal output from the acceleration sensor 14 is relatively stable, and the fluctuation is only a minute fluctuation such as a translational shake. Therefore, the above condition, “the average value of the sampling values for a predetermined number of times in the first AD converter ADC1 is within a predetermined range for a predetermined time or continuously for a predetermined number of times”, that is, the output from the first amplifier AMP1. Corresponds to a state in which the angle is determined and the camera posture is stable, for example. At this time, the output from the first amplifier AMP1 or an average value thereof includes the influence of the gravitational acceleration due to the camera posture. This roughly corresponds to the center value of the fluctuation of the camera shake signal. Therefore, if the output value or the average value at this time is the second reference voltage Vref2 of the second amplifier AMP2, signal amplification in the second amplifier AMP2 is amplification only for the translational shake component from which the offset value due to gravitational acceleration is removed. The detection sensitivity of the acceleration sensor 14 can be fully utilized.

  When the release operation is performed, the camera shake correction calculation unit 22 calculates the amount of movement of the movable part corresponding to the translational shake based on the sensor signal from the second AD converter ADC2, and outputs a drive signal to the actuator driver 24 to perform translation. Perform shake correction. However, when the sampling value of the second AD converter ADC2 exceeds the dynamic range, the data value acquired through the second AD converter ADC2 is saturated and a correct acceleration cannot be obtained. The translational blur correction using the value of the second AD converter ADC2 is prohibited until the condition in the first AD converter ADC1 is satisfied. During this time, the correction processing may be performed using the first AD converter ADC1, and in that case, a certain limitation may be imposed on the correction control such as limiting the correction width.

  Next, referring to the graph of FIG. 3, the signal from the first AD converter ADC <b> 1 and the second AD converter ADC <b> 2 in the camera shake correction calculation unit 22, the change timing of the second reference voltage Vref <b> 2, and the acceleration sensor 14 The relationship between the detected acceleration and the digital output in the first and second AD converters ADC1 and ADC2 will be described.

  The horizontal axis in FIG. 3 is time, and the left vertical axis is acceleration [G] detected by the acceleration sensor 14. The right vertical axis represents the output from the first amplifier AMP1 corresponding to the acceleration, the 12-bit digital output value (0 to 4095) of the first AD converter ADC1 that receives the output, and the second amplifier AMP2 corresponding to the acceleration. An output and a 12-bit digital output value (0 to 4095) of the second AD converter ADC2 that receives the output are shown. Further, in the lower part of FIG. 3, the timing of reading from the first AD converter ADC1 and the second AD converter ADC2 in the camera shake correction calculation unit 22 is shown.

  The first period T1 corresponds to a state in which the user is moving with a camera and a state in which various angles are being tested. In the period T1, the acceleration detected by the acceleration sensor 14 is greatly changed. When the angle is determined and the camera is held, the output of the acceleration sensor 14 is relatively stable and remains a minute change of translational shake. When the stabilization of the acceleration is confirmed in the period T2 (for example, corresponding to the determination that the camera is held) during the period T2, the camera shake correction calculation unit 22 updates the second reference voltage Vref2 described above at the time t0, and in the subsequent period T3, Continue the process. In other words, when the camera is set to translational blur correction ON and is in a shootable mode, the camera shake correction calculation unit 22 constantly monitors the output of the first AD converter ADC1, and the average value for a fixed number of samples is constant. If it falls within a certain change over time, the voltage value or average value at that time is output from the DA converter DAC, and the amplification reference voltage Vref2 of the second amplifier AMP2 is updated.

  Next, when the release switch is turned on at time t1, an exposure period T5 is started after the release time lag T4, and the output value from the second AD converter ADC2 is used for translational shake correction during exposure. However, in a single-lens reflex camera, there is a camera in which the output of the acceleration sensor 14 varies greatly due to a mirror shock or a shutter shock during an initial period T6 of the exposure period T5. In such a camera, the camera-specific vibration period T6 is measured and stored in advance, and the output value from the first AD converter ADC1 is continuously referred to during the vibration period T6 even during exposure. That is, during the vibration period T6, since the output of the acceleration sensor 14 varies greatly, the output from the second amplifier AMP2 is likely to exceed the dynamic range of the second AD converter ADC2, and during this period, the value of the first AD converter ADC1 is high. The correction operation is performed referring to.

  When the vibration period T6 ends, the camera shake correction calculation unit 22 starts referring to the output from the second AD converter ADC2, and corrects the translational shake generated in the exposure period T5 based on the digital output value from the second AD converter ADC2. Is executed in a period T7 until the exposure period T5 ends. Note that setting change of the second reference voltage Vref2 using the DA converter DAC is prohibited during the exposure period T5.

  When the exposure period T5 ends, the translational shake correction also ends, and the camera shake correction calculation unit 22 refers to the output value from the first AD converter ADC1 again. Note that the camera shake correction calculation unit 22 continues reading even in the broken line portion of the straight line indicating the reading timing of the first and second AD converters ADC1 and ADC2 in FIG. 3, and outputs values from both the first and second AD converters ADC1 and ADC2. May be read.

  In FIG. 3, the first amplification factor of the first amplifier AMP1 is such that the range of acceleration ± 2.0 [G], which is the detection range of the acceleration sensor 14, substantially corresponds to the digital output 0 to 4095 of the first AD converter ADC1. And the second amplification factor of the second amplifier AMP2 is such that the output range from the second amplifier AMP2 is sufficiently increased by the slight fluctuation of the translational fluctuation centered on the second reference voltage Vref2, and the second AD converter ADC2 Are set to correspond to the digital outputs 0 to 4095. In FIG. 3, about 0.6 [G] to 1.0 [G] is set to correspond to the digital output 0 to 4095 of the second AD converter ADC2.

  As described above, according to the first embodiment, the offset amount due to the gravitational acceleration is detected, and this is removed from the output of the acceleration sensor and amplified, so that the minute fluctuation of the translational shake is converted into a digital signal with high resolution. You can get it. Thereby, irrespective of the posture of the camera, it is possible to appropriately set the reference voltage of the amplifier circuit and correct the translational shake with high accuracy.

  In the first embodiment, the output signal of the first amplifier AMP1 is used as the input signal to the second amplifier AMP2. However, the output signal of the acceleration sensor 14 may be directly input to the second amplifier AMP2. . When the output of the first amplifier AMP1 is input to the second amplifier AMP2 as in the first embodiment, the second amplification factor of the second amplifier AMP2 may be set to an amplification factor larger than one, but the acceleration sensor 14 Is directly input to the second amplifier AMP2, the second amplification factor of the second amplifier AMP2 is set higher than the first amplification factor of the first amplifier AMP1.

  In the first embodiment, the second amplifier AMP2 is not used, and a switch is provided in a resistor or the like that determines the amplification factor of the first amplifier AMP1, so that the first amplifier AMP1 can select a plurality of amplification factors. However, there is a problem that the response is slow.

  Next, signal processing for translational shake correction in the second embodiment will be described with reference to FIG.

  FIG. 4 corresponds to FIG. 2 of the first embodiment. In the first embodiment, two first and second AD converters ADC1 and ADC2 are used. However, in the second embodiment, only one AD converter ADC is used, and an analog switch is provided in front of the AD converter ADC instead. Provide. That is, the output of the first amplifier AMP1 and the second amplifier AMP2 can be read by one AD converter ADC. The other configurations are the same as those in the first embodiment, and the same reference numerals are used for the same configurations, and descriptions thereof are omitted.

  The signals amplified by the first amplifier AMP1 and the second amplifier AMP2 of the amplifier circuit section 18A of the amplifier / filter circuit 18 are analog switches (AD / DA converter (ADC) 40) corresponding to the AD / DA converter (ADC) 20 ( SW) 42. The analog switch 42 alternatively outputs one of the two inputs to the AD converter ADC1. The signal converted into a digital signal by the AD converter ADC1 is input to the camera shake correction calculation unit 22 and processed in the same manner as in the first embodiment. The switching of the analog switch 42 is controlled by the camera shake correction calculation unit 22.

  As described above, in the configuration of the second embodiment, substantially the same effect as that of the first embodiment can be obtained. In the second embodiment, control while simultaneously reading the outputs of the first amplifier AMP1 and the second amplifier AMP2 cannot be performed, but a straight broken line indicating the read timing of the first and second AD converters ADC1 and ADC2 in FIG. The camera shake correction calculation unit 22 switches the selection of the analog switch 42 at the same timing.

  Next, signal processing for translational shake correction in the third embodiment will be described with reference to FIG.

  The configuration of the amplifier circuit unit 18A of the third embodiment and the configuration of the AD / DA converter (ADC) 40 are the same as those of the second embodiment. However, in the third embodiment, the setting unit for the second reference voltage Vref2 input to the second amplifier AMP2 is different from that in the second embodiment. That is, in the second embodiment, the second reference voltage Vref2 is set using the DA converter DAC. In the third embodiment, the analog voltage holding circuit (HOLD) 44 through the low-pass filter 43 is used. Yes. This configuration is useful, for example, in a system lacking a DA converter. In addition, about the structure similar to 1st, 2nd embodiment, the description is abbreviate | omitted using the same referential mark.

  The analog voltage holding circuit 44 includes two switches 46 and 48, and an output from the first amplifier AMP 1 is input to the second amplifier AMP 2 and input to the analog voltage holding circuit 44 through a low-pass filter (LPF) 43. Is done. The input from the low-pass filter 43 is input to the operational amplifier 50 used as a voltage follower via the switch 46, and the voltage can be recorded in the capacitor 52. That is, when the switch 46 is turned on while the switch 48 connected in parallel with the capacitor 52 is turned off, the capacitor 52 is charged, and when the switch 46 is turned off, the voltage is held. When the switch 48 is turned on, the capacitor 52 is discharged, and the held voltage is reset.

  The camera shake correction calculation unit 22 monitors the output from the first amplifier AMP1, and when the condition for setting the second reference voltage Vref2 described in the first embodiment is satisfied, the switch 48 is turned OFF and the switch 46 Is turned on for a predetermined time, and the output voltage from the first amplifier AMP 1 at that time is held in the capacitor 52. A voltage held in the capacitor 52 is output from the operational amplifier 50 and input to the second amplifier AMP2 as the second reference voltage Vref2.

  The low-pass filter 43 is for canceling noise and small translational shake components included in the output of the first amplifier AMP1 and then inputting them to the analog voltage holding circuit 44. A reference voltage that is not affected by noise and small translational fluctuations is used. Provided to get. The operational amplifier 50 and the capacitor 52 are preferably composed of parts with a small leakage current. The smaller the capacitance of the capacitor 50, the shorter the charging time and the faster the response.

  As described above, in the configuration of the third embodiment, substantially the same effects as those of the first and second embodiments can be obtained, and one DA converter can be omitted. Instead of the AD / DA converter (ADC) 40, the AD / DA converter (ADC) 20 of the first embodiment can be used.

  Next, signal processing for translational shake correction in the fourth embodiment will be described with reference to FIG.

  Although the basic configuration of the fourth embodiment is the same as that of the third embodiment, the operational amplifier 50 used as a voltage follower in the analog voltage holding circuit 44 of the third embodiment is replaced with the second amplifier AMP2. . In addition, about the structure similar to 1st-3rd embodiment, the description is abbreviate | omitted using the same referential mark.

  As the second amplifier AMP2 of the amplifier circuit section 54 of the amplifier / filter circuit 18, an operational amplifier such as C-MOS or Bi-MOS having a high input impedance is used. Although the output polarity of the second amplifier AMP2 is reversed from that of the third embodiment, since the polarity can be reversed by the camera shake correction calculation unit 22, the same processing as that of the third embodiment can be realized.

  As described above, also in the fourth embodiment, the same effect as in the third embodiment can be obtained, and the use of the operational amplifier can be reduced by one by keeping the input impedance on the analog voltage circuit 56 side high. In the fourth embodiment, the AD / DA converter (ADC) 20 of the first embodiment can be used instead of the AD / DA converter (ADC) 40.

  The present embodiment can also be applied to a single-lens reflex digital camera, a mirrorless digital camera, a compact camera, or other electronic devices having a camera function. The movable part may be provided with a lock mechanism.

DESCRIPTION OF SYMBOLS 10 Digital camera 14 Acceleration sensor 18A Amplification circuit part 20 AD / DA converter (ADC)
22 Shake Compensation Calculation Unit 24 Actuator Driver 26 Movable Part Moving Actuator ADC1 1st AD Converter ADC2 2nd AD Converter AMP1 1st Amplifier AMP2 2nd Amplifier DAC DA Converter Vref1 1st Reference Voltage Vref2 2nd Reference Voltage

Claims (12)

First amplification means for amplifying or offset adjusting a sensor signal from the acceleration sensor;
Second amplification means for amplifying the sensor signal or the signal from the first amplification means;
Reference voltage setting means for setting a reference voltage of the second amplification means based on an output from the first amplification means,
The signal processing apparatus, wherein an amplification factor of the output of the second amplification unit with respect to the sensor signal is higher than an amplification factor of the output of the first amplification unit with respect to the sensor signal.   2. The signal processing apparatus according to claim 1, wherein the setting of the reference voltage is performed when an output from the first amplifying unit satisfies a predetermined condition.   The signal processing apparatus includes AD conversion means, and outputs of the first amplification means and the second amplification means are converted into digital values by the AD conversion means. The signal processing device according to item.   The AD conversion means includes a first AD converter that AD converts the output of the first amplification means, and a second AD converter that AD converts the output of the second amplification means. The signal processing apparatus as described.   The AD conversion means comprises switching means for switching input between the output from the first amplification means and the output from the second amplification means, and one of the outputs from the first or second amplification means is digital The signal processing apparatus according to claim 3, wherein the signal processing apparatus converts the value into a value.   The signal processing apparatus according to claim 3, wherein the reference voltage is set based on a digital value of an output of the first amplifying unit.   7. The signal processing apparatus according to claim 6, wherein the signal processing apparatus includes DA conversion means, and a reference voltage of the second amplification means is output to the second amplification means via the DA conversion means. .   The voltage holding means for holding the output voltage of the first amplifying means is provided, and the reference voltage setting means sets the reference voltage to a voltage held in the voltage holding means. The signal processing device according to any one of the above.   9. The signal processing apparatus according to claim 8, wherein an amplifier is shared by the second amplifying unit and the voltage holding unit.   The signal processing apparatus according to claim 1, wherein the first amplifying unit transmits a signal of the acceleration sensor at an equal magnification.   A camera shake apparatus comprising the signal processing apparatus according to claim 1, wherein translational shake correction is performed based on an output of the second amplifying unit.   12. The imaging apparatus comprising the camera shake device according to claim 11, wherein the reference voltage setting unit does not change the setting of the reference voltage during an exposure period.

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