JP2010262096A - Vibration prevention control circuit and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately drive an optical element for a vibration prevention control of an imaging apparatus. <P>SOLUTION: A high-pass filter 200 includes: a low-pass filter 30 which receives an angular velocity signal outputted from a vibration detection element and transmits only the frequency components equal to or below a first frequency of the angular velocity signal; a latching unit 32 which latches the output of the low-pass filter 30 in accordance with a control signal; and a calculator 34 which calculates a difference between the angular velocity signal and the output of the latching unit 32. The angular velocity signal outputted from the vibration detection element of the imaging apparatus is processed by the high-pass filter 200. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image stabilization control circuit used for an imaging apparatus or the like.

  In recent years, an image pickup apparatus such as a digital still camera or a digital video camera achieves high image quality by increasing the number of pixels of an image pickup element provided therein. On the other hand, as another method for realizing high image quality of the image pickup device, the image pickup device is equipped with an image stabilization control circuit having a camera shake correction function in order to prevent subject shake caused by hand shake with the image pickup device. It is hoped to do.

  Specifically, the imaging apparatus includes a detection element such as a gyro sensor, and drives an optical component such as a lens or an imaging element according to an angular velocity component generated by vibration of the imaging apparatus to prevent subject blurring. Accordingly, even when the imaging apparatus vibrates, the vibration component is not reflected in the acquired video signal, and a high-quality video signal without image blur can be acquired.

  FIG. 7 shows a functional block diagram of the image stabilization control circuit. The image stabilization control circuit 100 includes an analog / digital conversion circuit (ADC) 10, an addition circuit 12, a servo circuit 14, a high-pass filter (HPF) 16, an integration circuit 22, a centering processing circuit 24, and a digital / analog conversion circuit (DAC) 26. It is comprised including.

  The image stabilization control circuit 100 is connected to the position detection element 102, the lens driving element 104, and the vibration detection element 106. The position detection element 102 is provided with respect to at least two axes so that the position of the lens driven by the lens driving element 104 can be measured so as to be at least orthogonally transformable. The vibration detection element 106 is also provided for at least two axes so that vibration components can be orthogonally transformed along two axes in the yaw direction and the pitch direction. The output signals of the position detection element 102 and the vibration detection element 106 are subjected to addition processing between the X-axis components and between the Y-axis components. Is controlled.

  The ADC 10 converts an analog voltage signal output from the position detection element 102, for example, a Hall element, into a digital signal. The Hall element generates an induced current according to the magnetic force generated by the magnet fixed to the lens, and outputs a voltage signal indicating the position of the lens according to the induced current. The ADC 10 converts the voltage signal into a digital signal and outputs it as a position signal (Hall-X, Hall-Y). The ADC 10 is configured to output a signal indicating a reference, for example, a digital value indicating “0”, when the optical axis of the lens coincides with the center of the image sensor provided in the imaging device. Further, the ADC 10 converts an analog angular velocity signal (Gyro-X, Gyro-Y) output from the vibration detection element 106, for example, a gyro sensor, into a digital signal. That is, the ADC 10 digitizes and outputs the output signals from the position detection element 102 and the vibration detection element 106 in a time division manner. The ADC 10 outputs the signals (Gyro-X, Gyro-Y) to the HPF 16 and outputs the signals (Hall-X, Hall-Y) to the adder circuit 12.

  The HPF 16 removes a direct current component included in the angular velocity signal output from the vibration detecting element 106 and extracts a high frequency component of the angular velocity signal reflecting the vibration of the imaging device. As shown in FIG. 8, the HPF 16 has a low-pass filter (LPF) 16a that transmits only a frequency band equal to or lower than a predetermined frequency of the input signal, an arithmetic unit 16b that outputs a difference between the input signal and the output value of the LPF 16a, Can be configured. Thereby, the HPF 16 outputs a signal obtained by cutting only the frequency band transmitted through the LPF 16a from the input signal.

  The integration circuit 22 integrates the angular velocity signal output from the HPF 16 and generates an angle signal indicating the amount of movement of the imaging device. The integration circuit 22 is preferably configured to include a digital filter (not shown), and obtains an angle signal, that is, a movement amount of the imaging device by performing filter processing according to a filter coefficient set in a register (not shown).

  The centering processing circuit 24 extracts a high frequency component by removing a low frequency component included in the angle signal output from the integration circuit 22. When camera shake correction processing is performed in the imaging apparatus, the lens position gradually moves away from the reference position while the correction processing is continuously performed, and may reach the vicinity of the limit point of the movable range of the lens. At this time, if the camera shake correction process is continued, the lens can move in one direction but cannot move in the other direction. The centering processing circuit 24 is provided to prevent this, and performs control so as not to approach the limit point of the movable range of the lens by subtracting a predetermined value from the angle signal.

  The adder circuit 12 adds the position signal (Hall-X) output from the ADC 10 and the vibration component signal (SV-X) of the X-axis component generated by the centering processing circuit 24, and also outputs the position signal (SV-X) output from the ADC 10. Hall-Y) and the vibration component signal (SV-Y) of the Y-axis component generated by the centering processing circuit 24 are added and output to the servo circuit 14. The servo circuit 14 generates a correction signal SR for controlling the driving of the lens driving element 104 in accordance with the output signal from the adding circuit 12. The servo circuit 14 includes a register and a digital filter circuit, and performs a filter process using a filter coefficient stored in the register. The DAC 26 converts the digital correction signal SR into an analog signal. Based on the correction signal SR analogized by the DAC 26, the lens of the imaging device is driven by the lens driving element 104 in the X-axis direction and the Y-axis direction, respectively.

JP-A-10-213832

  By the way, in the image stabilization control device, when the imaging device is set so that the subject is within the imaging range or when the subject is captured as a moving image, camera shake correction is greatly applied to vibrations with low frequency among vibrations to the imaging device. In addition, for high-frequency vibrations, processing that always moves the lens to the center together with camera shake correction is necessary.

  On the other hand, at the time of capturing a still image, the image capturing apparatus is fixed and used, and it is preferable that camera shake correction is greatly applied to vibration with a low frequency among vibrations with respect to the image capturing apparatus.

  Therefore, the present invention is not limited only to solve the above-mentioned problem, but in view of the above-described problem, an object of the present invention is to provide a vibration-proof control circuit that can be optimized for the vibration-proof control of an imaging apparatus. To do.

  One aspect of the present invention includes a high-pass filter that receives an angular velocity signal output from the vibration detection element and transmits a frequency band equal to or higher than a predetermined frequency, and the high-pass filter has a frequency equal to or lower than a first frequency of the angular velocity signal. A first low-pass filter that transmits a frequency component; a latch unit that latches an output of the first low-pass filter in accordance with a control signal; an arithmetic unit that outputs a difference between the angular velocity signal and an output of the latch unit; And an anti-vibration control circuit.

  Here, it is preferable that the latch unit executes a latch in accordance with the control signal indicating the start of still image capturing in the imaging apparatus.

  In addition, when releasing the latch in the latch unit, it is preferable to change the holding value of the latch unit step by step to the output value of the first low-pass filter.

  For example, the high-pass filter includes a comparator that compares an output value of the first low-pass filter with a holding value of the latch unit when releasing the latch in the latch unit, and the first in the comparator. When the output value of the low-pass filter is larger than the holding value of the latch unit, a predetermined value is added to the holding value of the latch unit, and when the output value of the first low-pass filter is smaller than the holding value of the latch unit And an addition / subtraction unit for subtracting a predetermined value from the holding value of the latch unit, and preferably changing the holding value of the latch unit to the output value of the first low-pass filter stepwise.

  The high-pass filter stops the operation of the first low-pass filter during at least a part of the latch period in the latch unit, and restarts the first low-pass filter when releasing the latch in the latch unit. By doing so, it is preferable to gradually change the holding value of the latch unit to the output value of the first low-pass filter.

  Moreover, it is preferable that the first low-pass filter includes at least a two-stage filter circuit.

  An integration circuit that integrates and outputs the output signal from the high-pass filter; a centering processing circuit that includes a high-pass filter that transmits a frequency component greater than a second frequency of the output signal from the integration circuit; and the centering processing circuit It is preferable to include a correction signal generation circuit that generates a correction signal for controlling the driving of the optical system element that is driven when performing the image stabilization control according to the signal output from.

  Another aspect of the present invention is an imaging apparatus that prevents blurring of a subject in response to vibration, the imaging apparatus including an optical system element, a drive element that drives the optical system element, and vibration of the imaging element. A vibration detection element that detects a vibration signal, and a vibration isolation control circuit that generates a correction signal for controlling the drive element based on a signal output from the vibration detection element. A high-pass filter that receives an angular velocity signal output from the filter and transmits a frequency band equal to or higher than a predetermined frequency, an integration circuit that integrates and outputs an output signal from the high-pass filter, and a first output signal from the integration circuit A centering processing circuit including a high-pass filter that transmits a frequency component greater than two frequencies, and the correction signal is generated according to a signal output from the centering processing circuit. A correction signal generation circuit, wherein the high-pass filter latches an output of the first low-pass filter according to a control signal and a first low-pass filter that transmits a frequency component equal to or lower than the first frequency of the angular velocity signal. An imaging apparatus comprising: a latch unit; and an arithmetic unit that outputs a difference between a signal output from the integration circuit and an output of the latch unit.

  ADVANTAGE OF THE INVENTION According to this invention, the drive of the optical element in image stabilization control of an imaging device can be optimized.

It is a figure which shows the structure of the high pass filter in 1st Embodiment. It is a figure which shows the effect | action of the high pass filter in 1st Embodiment. It is a figure which shows the structure of the high pass filter in 2nd Embodiment. It is a figure which shows the effect | action of the high pass filter in 2nd Embodiment. It is a figure which shows the structure of the high pass filter in 3rd Embodiment. It is a figure which shows the effect | action of the high-pass filter in 3rd Embodiment. It is a figure which shows the structure of an anti-vibration control circuit. It is a figure which shows the structure of the conventional high pass filter.

<First Embodiment>
As shown in FIG. 1, the high-pass filter (HPF) 200 in the embodiment of the present invention includes a low-pass filter (LPF) 30, a latch element 32, and an arithmetic unit 34.

  The HPF 200 in the present embodiment is an alternative to the HPF 16 of the image stabilization control circuit 100 shown in FIG. 7, receives an angular velocity signal output from the vibration detection element 106 as an input signal, and outputs a signal to the integration circuit 22. Is output. In the image stabilization control circuit 100, the components other than the HPF 200 are not changed, and therefore the HPF 200 will be described in detail below.

  The HPF 200 removes a direct current component included in the angular velocity signal output from the vibration detection element 106 and extracts a high-frequency component of the angular velocity signal reflecting the vibration of the imaging device. By this processing, slow vibration with a low vibration frequency among vibrations applied to the imaging device is removed, and it is possible to appropriately perform lens centering processing and camera shake correction.

LPF30 receives the angular velocity signal output from the vibration detecting element 106 as an input signal, and outputs the transmitting only the cutoff frequency f _c or less of the signal of the angular velocity signal. The LPF 30 can be configured with, for example, a digital filter, an RC circuit, an RL circuit, an RLC circuit, or the like. In FIG. 1, a primary IIR filter is used, and the frequency characteristics of the LPF 30 can be adjusted by changing the coefficients β0, β1, and β2 for the input signal, the register Z1, and the register Z2. The register Z1 and the register Z2 are memories that store an input signal and an output signal of the LPF 30, respectively.

  In response to the shutter signal SHOT, the latch element 32 is switched between a state in which the input signal is updated and the value Z3 is output, and a state in which the input signal is latched and output as the value Z3. When the shutter signal SHOT is OFF, the latch element 32 updates the value Z3 with the output value of the LPF 30 and outputs the updated value Z3 to the calculator 34. On the other hand, when the shutter signal SHOT is on, the latch element 32 latches the value Z3 at the timing when the shutter signal SHOT is turned on, and outputs the latched value Z3 to the calculator 34 until the shutter signal SHOT is turned off. To do.

  The calculator 34 subtracts the value Z3 input from the latch element 32 from the angular velocity signal output from the vibration detection element 106 and outputs the result.

  Next, the operation of the HPF 200 will be described with reference to FIG. FIG. 2 shows temporal changes in the input signal Sin to the HPF 200, the output value SLPF of the LPF 30, the output value Z3 of the latch element 32, the output signal Sout of the HPF 200, and the shutter signal SHOT.

When the imaging device is set so that the subject falls within the imaging range or when the subject is captured with a moving image, the shutter of the imaging device is not pressed. In this case, the shutter signal SHOT is turned off. When the shutter signal SHOT is off, the output value Z3 of the latch element 32 is continuously updated with the output value of the LPF 30. The calculator 34, an angular velocity signal output from the vibration detecting element 106, the difference processing between a cut-off frequency f _c or less of the signal of the angular velocity signal is performed. Therefore, the HPF200, and extracts and outputs only the signal of the cut-off frequency f _c is greater than the frequency component from the angular velocity signal output from the vibration detecting element 106.

  The output signal from the HPF 200 is sent to the integration circuit 22 and the centering processing circuit 24, where integration processing and centering processing are performed. In the adder circuit 12, the position signal (Hall-X, Hall-Y) output from the ADC 10 and the X-axis component vibration component signal (SV-X, SV-Y) generated by the centering processing circuit 24 are added. It is output to the servo circuit 14. The servo circuit 14 generates a correction signal SR for controlling the driving of the lens driving element 104 in accordance with the output signal from the adding circuit 12, and the imaging device based on the correction signal SR by the lens driving element 104 via the DAC 26. The lens is driven.

  As a result, when the imaging device is set so that the subject is within the imaging range or when the subject is captured with a moving image, the correction for shaking with a large vibration period in the imaging device is weakened, and the lens is always moved to the center. Processing that moves is emphasized. Also, when a still image is captured by pressing the shutter at the timing when the subject is within the imaging range, the correction range by camera shake correction can be maintained large.

  When the shutter of the imaging device is pressed to capture a still image, the shutter signal SHOT is turned on. At the timing when the shutter signal SHOT is turned on, the latch element 32 latches the output value of the LPF 30 and outputs it as the output value Z3 until the shutter signal SHOT is turned off. The computing unit 34 performs a difference process between the angular velocity signal output from the vibration detection element 106 and the output value Z3 latched by the latch element 32. Accordingly, the HPF 200 outputs a value obtained by subtracting the output value Z3, which is a constant value, from the angular velocity signal output from the vibration detecting element 106, that is, a signal that directly conveys the fluctuation of the angular velocity signal.

  As a result, at the time of capturing a still image, the frequency component of the vibration having a large vibration period in the imaging device is also processed by the integration circuit 22 and the centering processing circuit 24, and the camera shake correction for the low frequency vibration is strengthened.

<Second Embodiment>
By the way, when the HPF 200 in the first embodiment is applied, the LPF 30 continues to operate during the still image capturing period. Therefore, when the latch of the latch element 32 is released at the time when the shutter signal SHOT is turned off, the output value SLPF of the LPF 30 at that time and the value Z3 latched by the latch element 32 as shown in FIG. There is a possibility that the output value Sout of the HPF 200 greatly fluctuates at a time (location indicated by an arrow in FIG. 2).

  This causes the lens to move greatly when the still image capture is completed, causing image skipping in the viewfinder and LCD monitor, generating noise from the imaging device, The movement of the lens may be transmitted and cause a sense of incongruity.

  As shown in FIG. 3, the high-pass filter (HPF) 202 in the second embodiment includes a low-pass filter (LPF) 30, a switch element 36, a comparator 38, an adder / subtractor 40, a latch element 32, and an arithmetic unit 34. Consists of.

  The HPF 202 in the present embodiment is an alternative to the HPF 16 of the image stabilization control circuit 100 shown in FIG. 7, receives an angular velocity signal output from the vibration detection element 106 as an input signal, and outputs a signal to the integration circuit 22. Is output. In the image stabilization control circuit 100, the components other than the HPF 202 are not changed, and therefore the HPF 202 will be described in detail below.

LPF30 is configured similarly to the first embodiment, receives the angular velocity signal output from the vibration detecting element 106 as an input signal, and outputs the transmit only signals below cut-off frequency f _c of the angular velocity signal .

  The switch element 36 receives the shutter signal SHOT and the control signal C1 from the comparator 38, and connects / disconnects the output of the LPF 30 and the input of the latch element 32 according to the shutter signal SHOT and the control signal C1. Specifically, in synchronization with the timing when the shutter of the imaging device is pressed and the shutter signal SHOT is turned on (high level), the switch element 36 is opened, and the output of the LPF 30 and the input of the latch element 32 are cut off. The Further, in synchronization with the timing when the control signal C1 is turned on (high level), the switch element 36 is closed, and the output of the LPF 30 and the input of the latch element 32 are connected. A detailed description of the control signal C1 will be described later.

  The comparator 38 compares the register value Z2 included in the LPF 30 with the value Z3 of the latch element 32, and supplies the control signal C1 and the control signal C2 corresponding to the comparison result to the switch element 36 and the adder / subtractor 40, respectively. Output.

  The control signal C1 is generated as a signal indicating that the magnitude relationship between the value Z2 and the value Z3 is reversed. For example, the comparator 38 may determine the timing at which the value Z2 is shifted from the state in which the value Z2 is greater than the value Z3 to the state in which the value Z2 is smaller than the value Z3 or the value Z3 is greater than the value Z2 from the state in which the value Z3 is greater than the value Z2. The control signal C1 is turned from off (low level) to on (high level) at the timing of transition to a small state. The comparator 38 turns off the control signal C1 when a predetermined time has elapsed from the timing when the control signal C1 is turned on.

  The control signal C2 is generated as a signal corresponding to the magnitude relationship between the value Z2 and the value Z3. The comparator 38 sets the control signal C2 as an addition instruction signal when the value Z2 is larger than the value Z3, and sets the control signal C2 as a subtraction instruction signal when the value Z2 is smaller than the value Z3. When the value Z2 is equal to the value Z3, the control signal C2 may be either an addition instruction signal or a subtraction instruction signal, but in this embodiment, it is an addition instruction signal.

  The adder / subtractor 40 performs addition / subtraction between the value Z3 of the latch element 32 and the predetermined value α in accordance with the control signal C2 from the comparator 38, and outputs the calculation result to the latch element 32. When the control signal C2 is an addition instruction signal, the adder / subtracter 40 adds a predetermined value α to the current value Z3 of the latch element 32 and outputs the result to the latch element 32. When the control signal C2 is a subtraction instruction signal, the adder / subtracter 40 subtracts a predetermined value α from the current value Z3 of the latch element 32 and outputs the result to the latch element 32.

  The predetermined value α is preferably set to a value that changes stepwise so that the value of the latch element 32 is not changed suddenly after the still image capturing period ends. For example, it is preferable to set the predetermined value α in accordance with the average fluctuation range of the output value of the LPF 30 in the imaging apparatus in which the image stabilization control circuit 100 is mounted. Specifically, it is preferable to set the value to about 1/2 to 1/10 of the average fluctuation range of the output value of the LPF 30. For example, it is also preferable to set the predetermined value α according to the difference between the value Z2 and the value Z3 at the timing when the shutter signal SHOT changes from on to off. Specifically, it is preferable to set the value to about 1/2 to 1/10 of the difference between the value Z2 and the value Z3.

  The comparator 38 and the adder / subtractor 40 are preferably operated in synchronization with the timing when the shutter signal SHOT is changed from on to off. Further, it is preferable to stop the operations of the comparator 38 and the adder / subtractor 40 in synchronization with the timing when the control signal C1 is turned on in the comparator 38.

  In response to the shutter signal SHOT, the latch element 32 is switched between a state in which the input signal is updated and output as the value Z3, and a state in which the input signal is latched and output as the value Z3. When the shutter signal SHOT is off, the latch element 32 updates the value Z3 with the output value of the LPF 30 input via the switch element 36 if the switch element 36 is closed, and if the switch element 36 is open. The value Z3 is updated with the output value from the adder / subtractor 40, and the updated value Z3 is output to the calculator 34. On the other hand, when the shutter signal SHOT is on, the latch element 32 latches the value Z3 at the timing when the switch element 36 opens, and outputs the latched value Z3 to the calculator 34.

  The calculator 34 subtracts the value Z3 input from the latch element 32 from the angular velocity signal output from the vibration detection element 106 and outputs the result.

  Next, the operation of the HPF 202 will be described with reference to FIG. FIG. 4 shows temporal changes in the input signal Sin to the HPF 202, the output value SLPF of the LPF 30, the output value Z3 of the latch element 32, the output signal Sout of the HPF 202, and the shutter signal SHOT. FIG. 4 also includes a partially enlarged view for clearly showing the action of the HPF 202 in the embodiment of the present invention.

Shutter signal SHOT is off, if the switch element 36 is closed, LPF 30 receives the angular velocity signal output from the vibration detecting element 106, and transmits only the cutoff frequency f _c or less of the signal of the angular velocity signal Output. The latch element 32 outputs the value Z3 to the computing unit 34 while being updated with the output value from the LPF 30. The computing unit 34 performs a process of subtracting the value Z3 output from the latch element 32 from the angular velocity signal output from the vibration detecting element 106. Thus, as a whole HPF 202, a signal obtained by subtracting the frequency components of the following angular velocity signal cut-off frequency f _c from the angular velocity signal, i.e. the cut-off frequency f _c is greater than the frequency component of the angular velocity signal is output as an output signal Sout.

  The HPF 202 in the case where the switch element 36 is closed, as in the first embodiment, the centering process in which the correction for the vibration having a large vibration period is weakened in the imaging apparatus and the lens is always moved to the center. Is emphasized. Also, when a still image is captured by pressing the shutter at the timing when the subject is within the imaging range, the correction range by camera shake correction can be maintained large.

  When the shutter is pressed to capture a still image with the imaging device, the shutter signal SHOT is turned on from off. When the shutter signal SHOT is turned on, the latch element 32 latches and the switch element 36 is opened to disconnect the LPF 30 and the latch element 32. Thus, the constant value Z3 is output from the latch element 32 until the still image capturing is completed and the shutter signal SHOT is turned off. The computing unit 34 performs a process of subtracting a certain value Z3 from the angular velocity signal output from the vibration detecting element 106. That is, in the HPF 202, the change in the angular velocity signal output from the vibration detection element 106 is directly reflected in the output value Sout. As a result, at the time of capturing a still image, the frequency component of the shaking having a large vibration period in the imaging device is also processed in the integrating circuit 22 and the centering processing circuit 24, and the process of constantly moving the lens to the center is weakened, and the correction for camera shake is corrected. Strengthened.

  Note that the operation of the LPF 30 is continued even during the period when the shutter signal SHOT is on, and the value Z2 of the register included in the LPF 30 is continuously updated.

  When the still image capturing ends, the shutter signal SHOT is changed from on to off. When the shutter signal SHOT is turned off, the latch of the latch element 32 is released, and the comparator 38 and the adder / subtractor 40 start operation. The comparator 38 compares the value Z2 of the register included in the LPF 30 with the value Z3 of the latch element 32. As a result of comparison, when the value Z2 is larger than the value Z3, the addition instruction signal is output to the adder / subtractor 40 as the control signal C2, and when the value Z2 is smaller than the value Z3, the subtraction instruction signal is added or subtracted as the control signal C2. Is output to the device 40. When the control signal C2 is an addition instruction signal, the adder / subtracter 40 adds a predetermined value α to the current value Z3 of the latch element 32 and outputs the result to the latch element 32. The control signal C2 is the subtraction instruction signal. In this case, the predetermined value α is subtracted from the current value Z 3 of the latch element 32 and output to the latch element 32. The latch element 32 outputs the value Z3 to the calculator 34 while being updated with the output value from the adder / subtractor 40. This process is continued until the control signal C1 is turned on, that is, until the magnitude relationship between the value Z2 and the value Z3 is reversed. When the control signal C1 is turned on, the switch element 36 is closed, and the operations of the comparator 38 and the adder / subtractor 40 are stopped. Thus, the process returns to the process of removing the low frequency component of the normal angular velocity signal.

  By such processing, as indicated by an arrow in the partial enlarged view of FIG. 4, when the latch of the latch element 32 is released, the value Z3 of the latch element 32 can be changed step by step by a predetermined value α. Thus, it is possible to prevent the output signal Sout from the HPF 202 from changing suddenly. That is, the lens does not move suddenly when imaging of a still image is completed, and the occurrence of image skipping in the viewfinder and the liquid crystal monitor can be suppressed. In addition, noise from the imaging device can be reduced, and a sense of discomfort in the hand of the photographer can be suppressed.

<Third Embodiment>
As shown in FIG. 5, the HPF 204 in the third embodiment includes low-pass filters (LPF) 30-1 and 30-2, a latch element 32, a calculator 34, and a pre-stage filter 42.

  The HPF 204 in the present embodiment is an alternative to the HPF 16 of the image stabilization control circuit 100 shown in FIG. 7, receives an angular velocity signal output from the vibration detection element 106 as an input signal, and outputs a signal to the integration circuit 22. Is output. In the image stabilization control circuit 100, the components other than the HPF 204 are not changed, and the HPF 204 will be described in detail below.

  An angle signal from the integration circuit 22 is input to the HPF 204. The angle signal is input to the pre-stage filter 42 and the calculator 34. The pre-filter 42 performs a process such as adjusting the phase of the signal on the signal and outputs the signal to the LPF 30-1.

  In the present embodiment, two stages of LPFs 30-1 and 30-2 are provided. The LPFs 30-1 and 30-2 can be configured with, for example, a digital filter, an RC circuit, an RL circuit, an RLC circuit, or the like. In FIG. 5, each of the LPFs 30-1 and 30-2 is composed of a primary IIR filter. The register Z4 is a memory that stores an input signal of the LPF 30-1, and the register Z5 is a memory that stores an output signal of the LPF 30-1. The register Z1 is a memory that stores an input signal of the LPF 30-2, and the register Z2 is a memory that stores an output signal of the LPF 30-2. The LPF 30-1 obtains necessary frequency characteristics by changing the coefficients β3, β4, and β5 for the input signal, the register Z4, and the register Z5. The LPF 30-2 obtains necessary frequency characteristics by changing the coefficients β0, β1, and β2 for the input signal, the register Z1, and the register Z2.

Thus, by providing the two-stage LPFs 30-1 and 30-2, it is possible to improve the filtering characteristics as a low-pass filter. Here, the combination of LPF30-1,30-2 two stages, to have a characteristic to output only the cutoff frequency _{f c} or less of the frequency component of the input signal.

  Further, the LPFs 30-1 and 30-2 are configured to be able to be stopped and started according to the shutter signal SHOT. For example, the clock supply to the LPFs 30-1 and 30-2 can be stopped and started according to the shutter signal SHOT.

  Similarly to the second embodiment, the latch element 32 updates the value Z3 with the output value of the LPF 30-2 when the shutter signal SHOT is OFF, and outputs the updated value Z3 to the calculator 34. . On the other hand, when the shutter signal SHOT is on, the output value of the LPF 30-2 is latched, and the latched value Z3 is output to the calculator 34 until the shutter signal SHOT is turned off.

  The calculator 34 subtracts the value Z3 input from the latch element 32 from the angle signal input from the integration circuit 22 and outputs the result.

  Next, the operation of the HPF 204 will be described with reference to FIG. FIG. 6 shows temporal changes in the input signal Sin to the HPF 204, the output value SLPF of the LPF 30-2, the output value Z3 of the latch element 32, the output signal Sout of the HPF 204, and the shutter signal SHOT. FIG. 6 also includes a partially enlarged view for clearly showing the action of the HPF 204 in the embodiment of the present invention.

When the imaging device is set so that the subject falls within the imaging range or when the subject is captured as a moving image, the shutter signal SHOT is off, the LPFs 30-1 and 30-2 are in an operating state, and the latch element 32 is While being updated with the output value from the LPF 30-2, the value Z 3 is output to the computing unit 34. The computing unit 34 performs a process of subtracting the value Z3 output from the latch element 32 from the angular velocity signal output from the vibration detecting element 106. Thus, as a whole HPF204, signal minus the frequency components of the following angle signal cut-off frequency f _c from the angular velocity signal, i.e. the cut-off frequency f _c or more frequency components of the angular velocity signal is output as an output signal Sout. The centering signal thus generated and the position signals (Hall-X, Hall-Y) output from the ADC 10 are added and output to the servo circuit 14.

  When the shutter is pressed to capture a still image with the imaging device, the shutter signal SHOT is turned on from off. When the shutter signal SHOT is turned on, the latch element 32 latches and the operations of the LPFs 30-1 and 30-2 are stopped. Thus, a constant value Z3 is output from the latch element 32 until the shutter signal SHOT is turned off. The computing unit 34 performs a process of subtracting a certain value Z3 from the angular velocity signal output from the vibration detecting element 106. That is, the change in the angular velocity signal output from the vibration detection element 106 is directly reflected in the output value Sout.

  When the still image capturing ends, the shutter signal SHOT is changed from on to off. When the shutter signal SHOT is turned off, the latch of the latch element 32 is released and the LPFs 30-1 and 30-2 are restarted. As a result, the LPFs 30-1 and 30-2 enter an operating state, and the latch element 32 outputs the value Z3 to the computing unit 34 while being updated with the output value from the LPF 30-2. However, since the LPFs 30-1 and 30-2 are in an inoperative state until the shutter signal SHOT is changed to OFF, the output signal of the LPF 30-2 is based on the output value before the LPFs 30-1 and 30-2 are stopped. The output value gradually changes according to the input signal. The latch element 32 outputs the value Z3 to the calculator 34 while being updated with the output value from the LPF 30-2.

  As described above, when the latch of the latch element 32 is released, the output value of the LPF 30-2 that becomes the input signal of the latch element 32 gradually changes. Therefore, as shown by the arrows in the partially enlarged view of FIG. The output value Z3 of the element 32 is also gradually updated. Thereby, it is possible to prevent the output signal Sout from the HPF 204 from changing suddenly. That is, the lens does not move suddenly when imaging of a still image is completed, and the occurrence of image skipping in the viewfinder and the liquid crystal monitor can be suppressed. In addition, noise from the imaging device can be reduced, and a sense of discomfort in the hand of the photographer can be suppressed.

  In the present embodiment, both LPFs 30-1 and 30-2 are configured to stop and start according to the shutter signal SHOT. However, any LPF 30-2 that is the last stage may be stopped. For example, when the low-pass filter has a single stage, the low-pass filter may be configured to stop and start according to the shutter signal SHOT. When the number of low-pass filters is three or more, at least one low-pass filter including the last-stage low-pass filter closest to the latch element 32 may be configured to be stopped and started according to the shutter signal SHOT.

  In the present embodiment, the LPFs 30-1 and 30-2 are stopped during the entire period from when the shutter signal SHOT is turned on to when the shutter signal SHOT is turned off. , 30-2 may be stopped. Also in this case, the same operation and effect as the configuration in the present embodiment can be obtained to some extent.

  In the above description, processing such as image stabilization control (camera shake prevention) is realized by driving the lens, but the present invention is not limited to this. For example, instead of the lens, an image sensor (photoelectric conversion element such as a CCD) or another optical system element may be driven to change the relative arrangement of the lens and the other optical system element.

  Further, the present invention is not limited to the image stabilization control based on the feedback control using the position detection element 102 and the servo circuit 14, but is also applied to the image stabilization control using the signal output from the vibration detection element 106 and not using the feedback control. be able to.

  10 analog / digital conversion circuit (ADC), 12 addition circuit, 14 servo circuit, 16 high pass filter (HPF), 16a low pass filter (LPF), 16b arithmetic unit, 22 integration circuit, 24 centering processing circuit, 26 digital / analog conversion Circuit (DAC), 30 Low-pass filter, 32 Latch element, 34 Operation unit, 36 Switch element, 38 Comparator, 40 Adder / subtractor, 42 Pre-filter, 100 Anti-vibration control circuit, 102 Position detection element, 104 Lens drive element, 106 Vibration detection element, 200, 202, 204 High-pass filter.

Claims (8)

A high-pass filter that receives an angular velocity signal output from the vibration detection element and transmits a frequency band of a predetermined frequency or higher, and the high-pass filter includes:
A first low-pass filter that transmits a frequency component equal to or lower than the first frequency of the angular velocity signal;
A latch unit that latches an output of the first low-pass filter according to a control signal;
An arithmetic unit that outputs a difference between the angular velocity signal and the output of the latch unit;
An anti-vibration control circuit comprising: The image stabilization control circuit according to claim 1,
The image stabilization control circuit according to claim 1, wherein the latch unit executes latching according to the control signal indicating start of still image capturing in the image capturing apparatus. The image stabilization control circuit according to claim 1 or 2,
An anti-vibration control circuit that changes the holding value of the latch unit step by step to the output value of the first low-pass filter when releasing the latch in the latch unit. The image stabilization control circuit according to claim 3,
When the high-pass filter releases the latch in the latch unit,
A comparator for comparing the output value of the first low-pass filter with the holding value of the latch unit;
In the comparator, when the output value of the first low-pass filter is larger than the holding value of the latch unit, a predetermined value is added to the holding value of the latch unit, and the output value of the first low-pass filter becomes the value of the latch unit. An addition / subtraction unit that subtracts a predetermined value from the holding value of the latch unit when smaller than the holding value,
An anti-vibration control circuit that changes the holding value of the latch unit step by step to the output value of the first low-pass filter. The image stabilization control circuit according to claim 3,
The high-pass filter is
The operation of the first low-pass filter is stopped during at least a part of the latch period in the latch unit,
When the latch in the latch unit is released, the holding value of the latch unit is gradually changed to the output value of the first low-pass filter by restarting the first low-pass filter. Vibration control circuit. The image stabilization control circuit according to claim 4,
The anti-vibration control circuit, wherein the first low-pass filter includes at least a two-stage filter circuit. The image stabilization control circuit according to claim 1,
An integrating circuit for integrating and outputting the output signal from the high-pass filter;
A centering processing circuit including a high-pass filter that transmits a frequency component greater than a second frequency of the output signal from the integration circuit;
A correction signal generation circuit that generates a correction signal for controlling the driving of an optical element that is driven when performing the image stabilization control in accordance with a signal output from the centering processing circuit;
An anti-vibration control circuit comprising: An imaging device that prevents shaking of a subject in response to vibration, wherein the imaging device includes:
An optical element;
A driving element for driving the optical system element;
A vibration detecting element for detecting vibration of the imaging element;
An anti-vibration control circuit that generates a correction signal for controlling the drive element based on a signal output from the vibration detection element, and the anti-vibration control circuit includes:
A high-pass filter that receives an angular velocity signal output from the vibration detection element and transmits a frequency band of a predetermined frequency or higher;
An integrating circuit for integrating and outputting the output signal from the high-pass filter;
A centering processing circuit including a high-pass filter that transmits a frequency component greater than a second frequency of the output signal from the integration circuit;
A correction signal generation circuit that generates the correction signal in response to a signal output from the centering processing circuit, and the high-pass filter includes:
A first low-pass filter that transmits a frequency component equal to or lower than the first frequency of the angular velocity signal;
A latch unit that latches an output of the first low-pass filter according to a control signal;
An arithmetic unit that outputs a difference between the signal output from the integration circuit and the output of the latch unit;
An imaging apparatus comprising:

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