JP2012048138A - Optical equipment and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an image blur correction performance when changing a filter characteristic by preventing inconvenient image blur accompanying a change in the filter characteristic.SOLUTION: Optical equipment performing an image blur correction based on an output of a digital filter passing an optional frequency band of frequency components contained in an output signal of an angular velocity sensor includes: a panning control part for deciding a panning/tilting operation based on the output of the angular velocity sensor to control the frequency band of the digital filter; and an offset estimating part for estimating offset generated in an output signal of the digital filter according to a change in the frequency band in advance. The panning control part controls an intermediate value to be used in computation in the digital filter to be updated based on an output of the offset estimating part so that the offset generated in the output signal of the digital filter is canceled when changing the frequency band of the digital filter.

Description

  The present invention relates to an optical device having a function of correcting shake of an image by detecting a shake applied to the device, and a control method of the optical device.

  For example, in an optical apparatus such as a video camera or an imaging apparatus, various image blur correction functions for correcting a blur of a captured image caused by a shake (hand shake) of the apparatus have been proposed. However, if the characteristics of a filter that processes a signal related to image blur correction are suddenly switched in an optical device or an imaging apparatus having an image blur correction function, the output signal of the filter becomes discontinuous, resulting in an uncomfortable image. Problems arise. A stable image cannot be obtained when switching. Examples of the filter characteristic change include a case where the apparatus main body is intentionally moved, such as panning or tilting, and a case where the drive characteristic of the correction optical system is changed depending on the temperature characteristic. For example, in the case of panning, it is determined whether it is in a panning state (or tilting state), and control is performed to switch to a filter characteristic suitable for the state at that time. Switching of correction characteristics during panning (or tilting) is performed, for example, by switching a filter cutoff frequency. Patent Document 1 below proposes a technique for obtaining a stable image by gradually switching a filter cutoff frequency or time constant over a predetermined time in order to avoid abrupt switching. Yes.

JP-A-8-313950

  However, the conventional image blur correction function disclosed in Patent Document 1 has the following problems. In the conventional method, once the filter characteristics are switched, it takes a predetermined time to return to the normal characteristics. For example, the filter cut-off frequency remains shifted to the high frequency side until a predetermined time elapses after it is determined that panning has ended. This also attenuates the low-frequency component included in the camera shake component that is the subject of the image blur correction, and the image blur correction performance in the low-frequency component may be deteriorated. As described above, there is a problem that the image blur correction performance deteriorates when the characteristics of the filter are changed.

  The present invention has been made in view of such circumstances, and prevents inconvenient image blur due to a change in filter characteristics related to the image blur correction function, and improves image blur correction performance when the filter characteristics are changed. The purpose is to let you.

  The optical apparatus of the present invention is an optical apparatus having a function of correcting blurring of a captured image, and includes a shake detection unit that detects a shake applied to the optical device, and a frequency included in a signal output from the shake detection unit. Among the components, a digital filter that passes an arbitrary frequency band, a correction unit that corrects blurring generated in the captured image based on the output of the digital filter, and a panning / tilting operation based on the output of the shake detection unit Panning control means for controlling the frequency band of the digital filter according to the determination result, and offset estimation for estimating in advance the offset generated in the output signal of the digital filter when changing the frequency band of the digital filter And the panning control means adjusts the frequency band of the digital filter. In this case, the past calculation results that are sequentially held in the digital filter and used for the calculation in the digital filter are updated based on the output of the offset estimation means so as to cancel the offset generated in the output signal of the digital filter. The digital filter is controlled as described above.

  According to the present invention, it is possible to prevent inconvenient image blur due to a change in filter characteristics related to the image blur correction function, and to improve image blur correction performance when the filter characteristics are changed.

It is a figure which shows the structural example of the optical apparatus in 1st Embodiment. It is a figure which shows the structural example of a filter. It is a flowchart which shows the example of the filter control process in 1st Embodiment. It is a figure which shows the change of the cut-off frequency of the low-pass filter in 1st Embodiment. It is a figure for demonstrating the filter control in 1st Embodiment. It is a figure which shows the structural example of the optical instrument in 2nd Embodiment. It is a flowchart which shows the example of the filter control process in 2nd Embodiment. It is a figure for demonstrating the filter control in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A first embodiment of the present invention will be described.
FIG. 1 is a block diagram illustrating a configuration example of an optical apparatus according to the first embodiment. FIG. 1 illustrates an example of an imaging apparatus 100A to which the optical device according to the first embodiment is applied.

  In FIG. 1, an angular velocity sensor 101 detects a shake applied to the imaging apparatus 100A. The angular velocity sensor 101 includes, for example, an angular velocity sensor of a vibrating gyroscope, detects a shake of the device itself due to hand shake or the like as an angular velocity signal, and supplies the angular velocity signal to the DC cut filter 102. The DC cut filter 102 blocks a direct current (DC) component included in the angular velocity signal from the angular velocity sensor 101 and supplies only the alternating current component of the angular velocity signal, that is, the vibration component, to the amplifier 103. Note that a high-pass filter (high-pass filter, hereinafter referred to as “HPF”) that blocks an input signal in a predetermined frequency band may be used as the DC cut filter 102. The amplifier 103 amplifies the angular velocity signal (vibration component) from the DC cut filter 102 to an optimum sensitivity and supplies it to an A / D (analog-digital) converter 104. The A / D converter 104 digitizes the angular velocity signal from the amplifier 103 and supplies it to a microcomputer (microcomputer) 121 as angular velocity data.

  The microcomputer 121 includes an HPF 105, a low-pass filter (low-pass filter, hereinafter “LPF”) 106, a panning control unit 107 </ b> A, an offset estimation unit 108 </ b> A, a focal length correction unit 109, a control filter 110, and a calculator 122. The HPF 105 has a function of changing its characteristics in an arbitrary frequency band, and cuts off a low frequency component included in angular velocity data supplied from the A / D converter 104 and outputs a signal in a high frequency band. To do. The LPF 106 has a function capable of varying its characteristics in an arbitrary frequency band, integrates angular velocity data output from the HPF 105, and outputs the integration result as angular displacement data. The HPF 105 and the LPF 106 are configured by, for example, a first-order IIR (Infinite Impulse Response) filter as shown in FIG.

  FIG. 2 is a diagram illustrating a configuration example of an IIR filter applicable to the HPF 105 and the LPF 106. In FIG. 2, the adder 202 adds the input X (n) input to the input terminal 201 and the output of the multiplier 204, and outputs the calculation result as an intermediate value W (n). The delay unit 203 delays the intermediate value W (n) and outputs it as an intermediate value W (n−1). Multiplier 204 multiplies intermediate value W (n-1) by weighting factor a and outputs the result. The multiplier 205 multiplies the intermediate value W (n) by the weight coefficient b and outputs the result. The multiplier 206 multiplies the intermediate value W (n−1) by the weight coefficient c and outputs the result. The adder 207 adds the output of the multiplier 205 and the output of the multiplier 206 and outputs the calculation result as an output Y (n) from the output terminal 208.

  Returning to FIG. 1, the panning control unit 107 </ b> A determines the panning / tilting operation based on the angular displacement data output from the LPF 106, and performs panning control according to the determination result. If the angular displacement data (integration result) output from the LPF 106 is equal to or greater than a predetermined threshold, the panning control unit 107A determines that the panning state or the tilting state is appropriate, and the frequency band of the LPF 106 is suitable for the state. Set to value. Specifically, when it is determined that the panning control unit 107A is in the panning state or the tilting state, the cutoff frequency used for the integration calculation in the LPF 106 is shifted to a high frequency side (a direction in which the time constant is shortened). Let As a result, the correction position is gradually centered to the center of the moving range, and the value of the angular displacement data output from the LPF 106 becomes a reference value (a value that the angular displacement data can take in a state in which no shake is applied to the imaging device 100A). Gradually approaching. On the other hand, when it is determined that the panning control unit 107A is not in the panning state or the tilting state, the panning control unit 107A shifts the cutoff frequency used for the integration calculation in the LPF 106 to the low frequency side (in the direction in which the time constant becomes longer). As a result, the cut-off frequency used for the integration calculation in the LPF 106 is returned to the original state (state during normal operation), and the panning control is released.

  The offset estimation unit 108A is for estimating in advance an offset generated in the output signal of the LPF 106 when the cutoff frequency of the LPF 106 is changed by the panning control unit 107A. In the present embodiment, the LPF 106 is controlled by the output of the offset estimation unit 108A so as to cancel the offset of the output signal generated when the frequency characteristic of the LPF 106 is changed in accordance with the panning / tilting operation. .

  The imaging optical system 117 performs operations such as zooming and focusing, and forms a subject image on the image sensor 119. The zoom encoder 118 detects the zoom position of the imaging optical system 117 and outputs it to the focal length correction unit 109 inside the microcomputer 121. The focal length correction unit 109 calculates the focal length of the imaging optical system 117 using the output of the zoom encoder 118, and calculates the driving amount of the correction optical system 114 from the calculated focal length and the output (angular displacement data) of the LPF 106. To do. In the control filter 110, the output of the focal length correction unit 109 and the output of the position detection sensor 115 that detects the position of the correction optical system 114 calculated by the calculator 122 are digitized by the A / D converter 116. The difference from the value (position detection data) is input. The pulse width modulation unit 111 converts the output of the control filter 110 into a pulse width modulation (PWM) signal and outputs it. The motor drive unit 112 drives a motor 113 for moving the correction optical system 114 based on the PWM signal output from the pulse width modulation unit 111. By driving the correction optical system 114 in this manner, the optical blur of the captured image is optically corrected by changing the optical axis of the incident light on the imaging surface.

  The imaging element 119 converts the subject image formed by the imaging optical system 117 into an electrical signal and supplies the electrical signal to the signal processing unit 120. The signal processing unit 120 generates a video signal (video signal) based on, for example, the NTSC format from the signal obtained by the image sensor 119 and outputs it as captured image data.

Next, the control of the LPF 106 executed by the panning control unit 107A and the offset estimation unit 108A in the imaging apparatus 100A shown in FIG. 1 will be described. FIG. 3 is a flowchart illustrating an example of a filter control process in the imaging apparatus 100A.
In step S301, the A / D converter 104 converts the angular velocity signal output from the angular velocity sensor 101 and passed through the DC cut filter 102 and the amplifier 103 into digital data (angular velocity data). In step S302, the HPF 105 removes the low frequency component of the angular velocity data output from the A / D converter 104 by calculation, and extracts only the camera shake signal that is the target of image blur correction.

  In step S303, the panning control unit 107A determines whether or not the angular displacement data obtained by integrating the angular velocity data with the LPF 106 is equal to or greater than a predetermined threshold value. In other words, the panning control unit 107A determines whether the panning / tilting operation is performed based on the angular displacement data. The angular displacement data used in the determination in step S303 uses the result of integrating the angular velocity data acquired up to the previous time. If it is determined in step S303 that the angular displacement data is not equal to or greater than the predetermined threshold value, the process proceeds to step S304. In step S304, the panning control unit 107A turns off the panning control flag related to the LPF control included therein. Set to. Subsequently, in step S305, the panning control unit 107A sets the cutoff frequency of the LPF 106 to a normal cutoff frequency. On the other hand, if it is determined in step S303 that the angular displacement data is equal to or greater than the predetermined threshold value, the process proceeds to step S306, and in step S306, the panning control unit 107A turns on the panning control flag relating to the LPF control included therein. Set to (On). Subsequently, in step S307, the panning control unit 107A sets the cutoff frequency of the LPF 106 to a cutoff frequency during panning operation (a value higher than the normal cutoff frequency).

  Here, the cutoff frequency of the LPF 106 is determined based on the magnitude of the angular displacement data. For example, the cutoff frequency and the magnitude of the angular displacement data have a relationship as shown in the graph of FIG. The cutoff frequency of the LPF 106 increases in proportion to the angular displacement data (absolute value) with LFMAX as the upper limit. If the predetermined threshold value compared with the angular displacement data in step S303 is LPTH, the cutoff frequency of the LPF 106 when the angular displacement data is less than the threshold value LPTH is LFMIN. This LFMIN is a normal cutoff frequency of the LPF 106. That is, the cutoff frequency of the LPF 106 is set such that the larger the angular displacement data, the higher the cutoff frequency and the shorter the time for convergence to the reference value.

  In step S308, the panning control unit 107A compares the cutoff frequency of the LPF 106 used for the previous calculation with the cutoff frequency of the LPF 106 newly set this time, and determines whether or not the cutoff frequency has been changed. judge. If it is determined in step S308 that the cutoff frequency has been changed, in step S309, the panning control unit 107A controls the LPF 106 so as to update the intermediate value used in the calculation based on the output of the offset estimation unit 108A. . Thereby, the intermediate value used for the calculation in the LPF 106 is updated according to the output of the offset estimation unit 108A. Here, the intermediate value to be updated is a past calculation result that is sequentially held in the LPF 106 and used for internal calculation, and corresponds to the intermediate value W (n−1) shown in FIG. In step S310, the LPF 106 performs calculation (integration calculation) using the output of the HPF 105, and outputs the result as angular displacement data. If it is determined in step S308 that the cutoff frequency has not been changed, the process of step S309 is skipped and the process proceeds to step S310. After executing the process of step S310, the process returns to step S301.

  Here, the calculation method of the intermediate value used for the calculation in the LPF 106 in step S309 described above will be specifically described. First, the difference equation of the digital filter shown in FIG. 2 is expressed by the following (Equation 1).

Here, the coefficients of the multipliers 204, 205, and 206 at the cutoff frequency before being changed are a ₀ , b ₀ , and c _0, and the multipliers 204, 205, and 206 at the newly set cutoff frequency are The coefficients are a ₁ , b ₁ , and c ₁ . At this time, the outputs Y ₀ (n) and Y ₁ (n) when the input X (n) is input to the digital filter are as shown in the following (Formula 2).

Here, since it is desired to make the output result the same before and after the cutoff frequency of the digital filter is changed, if Y ₀ (n) = Y ₁ (n), the intermediate value at the newly set cutoff frequency The value W ₁ (n−1) can be expressed by the following (formula 3).

  That is, a new intermediate value is calculated from each coefficient before and after the cutoff frequency is changed and the intermediate value before the change, and the digital filter output is continuously connected by updating to the calculated intermediate value. be able to. Therefore, it is possible to maintain the continuity of the output signal of the digital filter and obtain a video with no sense of incongruity.

  Next, the effectiveness of the imaging apparatus according to the first embodiment will be described with reference to FIG. FIG. 5 is a diagram for explaining the filter control in the first embodiment, and shows the output signals of the respective parts when the panning operation is performed. FIG. 5 illustrates each case in order to compare the case where the intermediate value is updated when the cutoff frequency of the LPF 106 is changed with the case where the intermediate value is not updated. FIG. 5A is a graph showing the change with time of angular velocity data obtained by digitizing the angular velocity signal output from the angular velocity sensor 101 when the panning operation is performed by the A / D converter 104. FIG. 5B shows the angular displacement data output from the LPF 106 and FIG. 5C shows the cutoff frequency of the LPF 106 when the intermediate value is not updated when the cutoff frequency of the LPF 106 is changed. FIG. 5D shows the angular displacement data output from the LPF 106 and FIG. 5E shows the cutoff frequency of the LPF 106 when the intermediate value is updated when the cutoff frequency of the LPF 106 is changed. Yes.

  In step S303 of FIG. 3, the threshold for shifting to panning control is set to LPTH, and is set as shown in FIG. Until time T11, the angular displacement data output from the LPF 106 is in the range of (−LPTH) to LPTH, and therefore the cutoff frequency of the LPF 106 is set to LFMIN regardless of the magnitude of the angular displacement data. . As shown in FIG. 3C, until the time T11, the angular velocity data is integrated with the cut-off frequency of the LPF 106 being LFMIN. At time T11, since the angular displacement data exceeds the threshold value LPTH, the LPF 106 is calculated by sequentially changing to the cutoff frequency corresponding to the angular displacement data as shown in FIG. However, since the intermediate value is not updated when the cutoff frequency of the LPF 106 is changed, the output of the LPF 106 becomes a discontinuous signal as shown in FIG. When image blur correction of an image is performed based on such angular displacement data, there arises a disadvantage that the captured image is unnaturally blurred. In addition, the cut-off frequency of the LPF 106 increases frequently between times T12 and T13, and discontinuity occurs in the angular displacement data each time. For this reason, there arises a problem that the image blur correction effect with respect to the low frequency component of the camera shake signal is deteriorated because the image is unnaturally blurred or the cutoff frequency of the LPF 106 is increased.

  On the other hand, in the image pickup apparatus according to the present embodiment, the cut-off frequency of the LPF 106 is changed based on the angular displacement data, and the intermediate value used for the calculation in the LPF 106 is updated, thereby causing the discontinuity in the angular displacement data. Control is performed so as not to occur. In step S303 in FIG. 3, the threshold for shifting to panning control is set to LPTH, and is set as shown in FIG. Until time T11, the angular displacement data output from the LPF 106 is in the range of (−LPTH) to LPTH, and therefore the cutoff frequency of the LPF 106 is set to LFMIN regardless of the magnitude of the angular displacement data. . As shown in FIG. 3E, until the time T11, the angular velocity data is integrated in a state where the cutoff frequency of the LPF 106 is LFMIN. At time T11, since the angular displacement data exceeds the threshold value LPTH, the LPF 106 is calculated by sequentially changing to the cutoff frequency corresponding to the angular displacement data as shown in FIG. In this embodiment, when the cut-off frequency of the LPF 106 is changed, the intermediate value (the past calculation result that is sequentially held in the LPF 106 and used for the calculation) is updated. Therefore, as shown in FIG. In this case, the output result of the LPF 106 does not become discontinuous. At time T12, the angular displacement data again falls within the range of (−LPTH) to LPTH, so that the cutoff frequency of the LPF 106 is set to LFMIN, and normal camera shake correction is restored. Compared with the case shown in FIG. 3B, in the present embodiment, it is possible to correct even the low frequency component of the camera shake signal during the time T12 to T13.

  According to the first embodiment, the cutoff frequency (frequency band) of the LPF 106 is changed according to the determination result of the panning / tilting operation, and the intermediate value used for the calculation in the LPF 106 is changed when the cutoff frequency is changed. Thereby, it becomes possible to change the cut-off frequency of the LPF 106 abruptly, and it is possible to prevent a discontinuous signal from being output to the output of the LPF 106 even if the cut-off frequency is changed abruptly. Therefore, it is possible to arbitrarily change to the desired characteristics during the panning operation or after the end of the panning operation, and it becomes unnecessary to gradually change the cut-off frequency over a predetermined time, and image blur correction after the panning operation is completed. The effect can be improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
The second embodiment further controls the cut-off frequency of the HPF 105 based on the angular velocity data obtained by digitizing the angular velocity signal output from the angular velocity sensor 101 as compared with the first embodiment, and thereby the angular velocity data. The low-frequency component of is attenuated. FIG. 6 is a block diagram illustrating a configuration example of the optical apparatus according to the second embodiment. FIG. 6 illustrates an example of an imaging apparatus 100B to which the optical device according to the second embodiment is applied. Further, in FIG. 6, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  The imaging apparatus 100B shown in FIG. 6 is that the panning control unit 107B controls the cutoff frequency of the LPF 106 according to the angular displacement data, and also controls the cutoff frequency of the HPF 105 according to the angular velocity data. It is different from the imaging apparatus 100A shown in FIG. Further, when the cutoff frequency of the HPF 105 is changed, the HPF 105 is controlled so as to update the intermediate value used in the calculation based on the output of the offset estimation unit 108B so as to cancel the offset of the output signal that occurs along with the change. .

  As with the panning control unit 107A shown in FIG. 1, the panning control unit 107B determines the panning / tilting operation using the angular displacement data output from the LPF 106, and sets the cut-off frequency of the LPF 106 to the state. Set the value to Further, the panning control unit 107B determines the panning / tilting operation using the angular velocity data output from the A / D converter 104, and sets the cutoff frequency of the HPF 105. For example, the panning control unit 107B shifts the cutoff frequency of the HPF 105 to the high frequency side when the angular velocity data output from the A / D converter 104 becomes equal to or higher than the first threshold, and is within the second threshold. When this happens, the cutoff frequency of the HPF 105 is shifted to the low frequency side. Thereby, the magnitude of the angular velocity data input to the LPF 106 can be limited, and the angular displacement data output from the LPF 106 can be prevented from becoming an abnormally large value. For example, it is assumed that the angular velocity signal output from the angular velocity sensor 101 becomes a very large value due to a rapid panning operation or the like. Even in this case, the angular displacement data output from the LPF 106 can be returned to the vicinity of the center by shifting the cutoff frequency of the HPF 105 to the high frequency side to attenuate the low frequency component. Note that the first threshold value and the second threshold value may be different values or the same value.

  The offset estimation unit 108B is for estimating in advance the offset generated in the output signals of the digital filters 105 and 106 when the cutoff frequency of the digital filters 105 and 106 is changed by the panning control unit 107B. The digital filters 105 and 106 are controlled by the output of the offset estimation unit 108 </ b> B so as to cancel the offset of the output signal generated with the change of the cutoff frequency of the digital filters 105 and 106.

  Next, control of the digital filters 105 and 106 executed by the panning control unit 107B and the offset estimation unit 108B in the imaging device 100B illustrated in FIG. 6 will be described. Note that the process for controlling the cutoff frequency of the LPF 106 based on the angular displacement data is the same as the process shown in the flowchart of FIG. 3 in the first embodiment, and a description thereof will be omitted.

FIG. 7 is a flowchart illustrating an example of a filter control process related to the HPF 105 in the imaging apparatus 100B.
In step S701, the A / D converter 104 converts the angular velocity signal output from the angular velocity sensor 101 and passed through the DC cut filter 102 and the amplifier 103 into digital data (angular velocity data). In step S702, the panning control unit 107B determines whether or not a panning control flag related to HPF control included therein is ON.

  If it is determined in step S702 that the panning control flag related to HPF control is ON, the process proceeds to step S703. In step S703, the panning control unit 107B determines that the angular velocity data is within a predetermined threshold (second threshold). It is determined whether or not. If it is determined in step S703 that the angular velocity data is within a predetermined threshold (second threshold), the process proceeds to step S704, and in step S704, the panning control unit 107B turns off the panning control flag related to HPF control. Set to (Off). Subsequently, in step S705, the panning control unit 107B sets the cutoff frequency of the HPF 105 to a normal cutoff frequency, that is, a low-frequency value. If it is determined in step S703 that the angular velocity data is not within the predetermined threshold (second threshold), the processing of steps S704 and S705 is skipped and the process proceeds to step S709.

  On the other hand, if it is determined in step S702 that the panning control flag related to HPF control is OFF, the process proceeds to step S706. In step S706, the panning control unit 107B determines that the angular velocity data has a predetermined threshold value (first threshold value). ) Determine whether or not. If it is determined in step S706 that the angular velocity data is equal to or greater than the predetermined threshold (first threshold), the process proceeds to step S707, and in step S707, the panning control unit 107B sets the panning control flag related to HPF control. Set to ON. Subsequently, in step S708, the panning control unit 107B sets the cutoff frequency of the HPF 105 to the cutoff frequency during the panning operation, that is, a value on the high frequency side. If it is determined in step S706 that the angular velocity data is not equal to or greater than the predetermined threshold (first threshold), the processing in steps S707 and S708 is skipped and the process proceeds to step S709.

  In step S709, the panning control unit 107B compares the cutoff frequency of the HPF 105 used for the previous calculation with the cutoff frequency of the HPF 105 newly set this time, and determines whether or not the cutoff frequency has been changed. judge. If it is determined in step S709 that the cutoff frequency has been changed, in step S710, the panning control unit 107B controls the HPF 105 so as to update the intermediate value used for the calculation based on the output of the offset estimation unit 108B. . Thereby, the intermediate value used for the calculation in the HPF 105 is updated according to the output of the offset estimation unit 108B. Here, the intermediate value to be updated is a past calculation result that is sequentially held in the HPF 105 and used for internal calculation, and corresponds to the intermediate value W (n−1) shown in FIG. If it is determined in step S709 that the cutoff frequency has not been changed, the process of step S710 is skipped and the process proceeds to step S711. In step S711, the HPF 105 performs an operation and removes the low frequency component of the angular velocity data output from the A / D converter 104. In step S712, the LPF 106 performs an operation (integration operation) using the output of the HPF 105, and outputs the result as angular displacement data. After executing the process of step S712, the process returns to step S701.

Here, a method of updating the intermediate value used for the calculation in the HPF 105 in step S710 will be described. The HPF 105 shown in FIG. 6 includes a first-order IIR filter as shown in FIG. 2 in the same manner as the LPF 106 shown in FIG. The only difference between the HPF 105 and the LPF 106 is that the values of the coefficients a, b, and c used in the calculation are different. Accordingly, the calculation of the intermediate value is performed by setting each coefficient a ₀ , b ₀ , c ₀ at the cutoff frequency before change in the multipliers 204, 205, and 206, as well as the LPF 106 shown in FIG. obtained from the relationship of the coefficients a _1, b _1, c ₁ at the cut-off frequency. The intermediate value W ₁ (n−1) at the newly set cutoff frequency can be expressed by the above-described (Expression 3). In this way, a new intermediate value is calculated from each coefficient before and after the cutoff frequency is changed and the intermediate value before being changed, and the digital filter output is continuously updated by updating to the calculated intermediate value. It is possible to connect to.

  Next, the effectiveness of the imaging apparatus according to the second embodiment will be described with reference to FIG. FIG. 8 is a diagram for explaining the filter control in the second embodiment, and shows the output signals of the respective parts when the panning operation is performed. In FIG. 8, in order to compare the case where the intermediate value is updated when the cutoff frequency of the HPF 105 is changed with the case where the update is not performed, the respective cases are illustrated. FIG. 8A is a graph showing a change with time of angular velocity data obtained by digitizing the angular velocity signal output from the angular velocity sensor 101 by the A / D converter 104 when the panning operation is performed. FIG. 8B is a graph showing a change with time of the cutoff frequency used for the calculation of the HPF 105. FIG. 8C shows the angular velocity data output from the HPF 105 when the intermediate value is not updated when the cutoff frequency of the HPF 105 is changed. FIG. 8D shows the angular velocity data output from the HPF 105 when the intermediate value is updated when the cutoff frequency of the HPF 105 is changed.

  In step S706 of FIG. 7, the threshold value for shifting to panning control (first threshold value) is PTH, and in step S703, the threshold value for releasing panning control (second threshold value) is PETH, which is set as shown in FIG. To do. Until time T21, since the angular velocity data is within the range of the first threshold value PTH, the HPF 105 is set to HFCL which is a cutoff frequency when the panning control is OFF. At time T21, since the angular velocity data exceeds the first threshold value PTH, it is determined that panning control is performed. As shown in FIG. 8B, the HPF 105 is set to HFCH, which is a cutoff frequency at the time of panning control. Is done. At time T22, since the angular velocity data falls below the second threshold value PETH, the panning control is canceled, and the HPF 105 is set to HFCL, which is a cutoff frequency when the panning control is OFF.

  Here, when attention is paid to the output of the HPF 105 when the intermediate value is not updated when the cutoff frequency of the HPF 105 is changed, the output of the HPF 105 is output at times T21 and T22 as shown in FIG. Becomes a discontinuous signal. If image blur correction is performed on the basis of angular displacement data obtained by integrating such angular velocity data, there arises a disadvantage that the captured image blurs unnaturally.

  On the other hand, in the imaging apparatus according to the present embodiment, the cutoff frequency of the HPF 105 is changed based on the angular velocity data, and the intermediate value used for the calculation in the HPF 105 is updated so that the angular velocity data does not become discontinuous. Control is in progress. As shown at times T21 and T22 in FIG. 8D, the output result of the HPF 105 does not become discontinuous. FIG. 8E shows angular displacement data obtained by integrating the angular velocity data shown in FIG. As shown in FIG. 8 (e), there is no discontinuity in the output waveform of the LPF 106, and good image blur correction is performed by performing image blur correction based on the angular displacement data obtained here. be able to.

  According to the second embodiment, the cut-off frequency (frequency band) of the digital filters 105 and 106 is changed according to the determination result of the panning / tilting operation, and at the time of the change, the intermediate used for the calculation in the digital filters 105 and 106 is performed. Change the value. As a result, the cutoff frequency of the digital filters 105 and 106 can be rapidly changed, and discontinuous signals can be prevented from being output to the outputs of the digital filters 105 and 106. Therefore, it is possible to arbitrarily change to the desired characteristics during or after the panning operation, and it is not necessary to gradually change the cutoff frequency over a predetermined time. Can be improved.

  In the above description, the case where a primary IIR filter is used as a digital filter has been described as an example. However, the present invention is not limited to this. For example, a secondary or higher order IIR filter or FIR filter may be used as the digital filter. Further, although the correction optical system 119 (for example, a shift lens) has been described as an example of a means for performing image blur correction, the present invention is not limited to this. For example, image blur correction may be performed using a variable apex angle prism (VAP), a method of driving the image sensor in a direction perpendicular to the optical axis (a direction orthogonal to the optical axis), or the like. Further, the present invention can also be used for a method of electronically correcting image blur by moving the image cutout position according to shake detection.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the third embodiment, the IIR filter of the present invention can be applied to a control filter for controlling the correction optical system with the same device configuration as the first embodiment and the second embodiment. That is, the control filter 110 in FIG. 1 or FIG. 6 is configured by a digital filter so that the control characteristic (for example, phase delay compensation) of the correction optical system 114 (for example, shift lens) as the correction member can be changed. This configuration is used when the viscosity is changed by a change in temperature and the control characteristics of the correction optical system 114 need to be changed, such as when a viscous member (eg, gel) is involved in driving the correction optical system 114. Can be used.

  In the present embodiment, the correction optical system 114 as a correction member has a temperature measurement unit (not shown) that measures the temperature around the correction member, and the temperature measurement result is input to the control filter 110. Yes. Then, a new intermediate value is calculated from each coefficient before and after the temperature around the correction member measured by the temperature measuring means and the intermediate value before the change, and the intermediate value currently held is newly calculated. Update to the calculated intermediate value. Thereby, the output of the control filter 110 can be continuously connected. For example, when the temperature measured by the temperature measuring unit becomes high, the control filter 110 before and after the temperature change is updated by updating the intermediate value so that the phase delay amount of the image blur correction signal used for the image blur correction becomes small. Can be connected continuously. Here, the intermediate value to be updated is a past calculation result that is sequentially held in the control filter 110 and used for internal calculation, and corresponds to the intermediate value W (n−1) shown in FIG.

  As a result, the continuity of the output signal of the control filter 110 can be maintained, a sudden change in the shift lens position due to the change in the control characteristics can be prevented, and an image without a sense of incongruity can be obtained.

(Other embodiments of the present invention)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

  DESCRIPTION OF SYMBOLS 100A * 100B ... Imaging device, 101 ... Angular velocity sensor, 105 ... High pass filter, 106 ... Low pass filter, 107A / 107B ... Panning control part, 108A / 108B ... Offset estimation part, 109 ... Focal length correction part, 114 ... Correction optical system

Claims (9)

An optical device having a function of correcting blurring of a captured image,
Shake detection means for detecting shake applied to the optical device;
Among the frequency components included in the signal output from the shake detection means, a digital filter that passes an arbitrary frequency band, and
Correction means for correcting blur occurring in the captured image based on the output of the digital filter;
Panning / tilting operation is determined based on the output of the shake detection unit, and the panning control unit controls the frequency band of the digital filter according to the determination result;
Offset estimating means for preliminarily estimating an offset generated in the output signal of the digital filter when changing the frequency band of the digital filter;
When the frequency band of the digital filter is changed, the panning control means sequentially stores in the digital filter so as to cancel the offset generated in the output signal of the digital filter, and uses the past calculation used for the calculation in the digital filter. An optical apparatus, wherein the digital filter is controlled to update a result based on an output of the offset estimating means.   The panning control means sets the cut-off frequency of the digital filter to a normal cut-off frequency when it is determined that the panning / tilting operation is not performed based on the determination of the panning / tilting operation. 2. The optical apparatus according to claim 1, wherein when it is determined to be an operation, the cutoff frequency of the digital filter is shifted to a value higher than a cutoff frequency at a normal time.   The optical apparatus according to claim 1, wherein the digital filter includes a low-pass filter.   4. The optical according to claim 3, wherein the panning control unit changes the frequency band of the digital filter based on an angular displacement obtained by integrating an angular velocity that is an output of the shake detection unit. machine.   The optical apparatus according to claim 3, wherein the digital filter includes a high-pass filter.   The optical apparatus according to claim 5, wherein the panning control unit changes a frequency band of the digital filter based on an angular velocity that is an output of the shake detection unit. An optical device having a function of correcting blurring of a captured image,
Shake detection means for detecting shake applied to the optical device;
A digital filter capable of changing the characteristics of the image blur correction signal based on the output of the shake detection means;
Correction means for correcting blur caused in the captured image by driving a correction member in a direction orthogonal to the optical axis based on the output of the digital filter;
Temperature measuring means for measuring the temperature around the correction member;
The digital filter is sequentially held by the digital filter so as to cancel the offset generated in the output signal of the digital filter when the temperature measurement means changes the temperature around the correction member. An optical apparatus, wherein a past calculation result used for calculation is updated based on an output of the temperature measuring means. The digital filter is a digital filter capable of changing at least a phase delay amount of the image blur correction signal,
The optical apparatus according to claim 7, wherein when the temperature becomes high, the past calculation result is updated so that the phase delay amount becomes small. A method for controlling an optical device having a function of correcting blurring of a captured image,
A shake detection step of detecting shake applied to the optical device;
Of the frequency components included in the signal obtained in the shake detection step, a correction step of correcting blur occurring in the captured image based on an output of a digital filter that passes an arbitrary frequency band;
A panning / tilting operation is determined based on an output of the shake detection step, and a panning control step for controlling a frequency band of the digital filter according to a determination result;
An offset estimation step for preliminarily estimating an offset generated in the output signal of the digital filter when the frequency band of the digital filter is changed,
In the panning control step, when the frequency band of the digital filter is changed, the past calculation that is sequentially held in the digital filter and used for the calculation in the digital filter so as to cancel the offset generated in the output signal of the digital filter A method for controlling an optical apparatus, comprising: controlling the digital filter so as to update a result based on an output of the offset estimation step.

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