JP3937574B2 - Imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video camera or other imaging apparatus having a camera shake correction function, and more particularly to a camera that improves camera shake correction performance during shooting without pan / tilt or still image shooting.
[0002]
[Prior art]
As a hand shake correction method in a handy type video camera, there are an electronic correction method and an optical correction method. Among these, the electronic correction method calculates information necessary for camera shake correction based on a signal obtained by A / D (analog / digital) conversion of the camera camera shake detection output by an angular velocity sensor or the like, and based on this information. Thus, the driving of the vertical transfer CCD of the CCD image pickup device and the processing in the video signal processing LSI are controlled.
[0003]
Similarly, the optical correction method calculates information necessary for camera shake correction based on a signal obtained by A / D (analog / digital) conversion of a camera shake detection output from an angular velocity sensor or the like, and based on this information. A vari-angle prism is driven.
[0004]
In such a camera shake correction method, the calculation performed to calculate information necessary for camera shake correction includes the following process.
(A) A low-pass component of angular velocity sampling value data from the A / D converter is cut by a high-pass filter.
(B) The gain of the output signal of the high-pass filter is adjusted based on the focal length information of the lens.
(C) A shake-adjusted angular velocity displacement signal is generated by integrating the gain-adjusted signal with an integration filter.
[0005]
Conventionally, in a video camera having such a camera shake correction function, integration by the integration filter of (c) above is always performed at a constant cut-off frequency among calculations for calculating information necessary for camera shake correction.
In other words, as this cutoff frequency is increased, camera shake correction is not performed in the low frequency range, so the camera shake correction performance deteriorates, but pan / tilt (shooting while moving or tilting the camera up / down / left / right) Motion) (unfavorable screen movements such that the screen moves in the same direction as the pan / tilt direction after panning / tilting is completed, and then the screen moves back to the center). On the other hand, as the cut-off frequency is lowered, camera shake correction is performed even in a low frequency region, so that the camera shake correction performance is improved, but the back-up during pan / tilt is increased. Therefore, conventionally, this cut-off frequency is determined as a fixed value in consideration of the camera shake correction performance and the amount of backlash.
[0006]
[Problems to be solved by the invention]
However, the cut-off frequency of the integral filter, which is determined based on the balance between the camera shake correction performance and the amount of the shakeback, is not an optimal value from the viewpoint of improving the camera shake correction performance.
[0007]
The present invention has been made in view of the above-described points, and is intended to provide a video camera or other imaging apparatus having a camera shake correction function, which has improved camera shake correction performance.
[0008]
[Means for Solving the Problems]
An imaging apparatus according to a first aspect of the present invention includes a high-pass filter that cuts a low-frequency component of a camera shake detection output of the imaging apparatus, and an angular velocity displacement signal of the camera shake by integrating the output signal of the high-pass filter. In an imaging device having an integral filter that generates a correction and correcting a camera shake based on the angular velocity displacement signal , a still subject mode in which shooting is performed without displacing the imaging device, and shooting by displacing the imaging device The selection means for selecting one of the normal mode for performing the operation, and the cutoff frequency of the integration filter when the stationary subject mode is selected by the selection means is lower than the frequency when the normal mode is selected. And switching means for switching to.
[0009]
The background to devise this imaging device is as follows. When taking a picture without displacing the imaging device (in other words, without panning / tilting), it is not necessary to consider the amount of reversing. There is room for improving camera shake correction performance by further lowering the cut-off frequency of the integral filter that generates the camera shake angular velocity displacement signal than when shooting (while tilting).
[0010]
Therefore, according to this image pickup apparatus, when the photographer tries to take a picture without panning / tilting, when the still object mode for taking a picture without displacing the image pickup apparatus is selected by the selection means, the switching means Therefore, the cutoff frequency of the integration filter can be switched to a lower frequency than when the normal mode in which shooting is performed by displacing the imaging device is selected . The camera shake correction performance is improved compared to the conventional one.
[0011]
Next, an imaging apparatus according to claim 2 of the present invention has a still image shooting function, a high-pass filter that cuts a low-frequency component of a camera shake detection output of the imaging apparatus, and an output of the high-pass filter In an imaging apparatus having an integration filter that generates an angular velocity displacement signal of camera shake by integrating the signal , and correcting the camera shake based on the angular velocity displacement signal , either a still image shooting mode or a movie shooting mode comprising selecting means for selecting either a switching means for switching to a frequency lower than the cutoff frequency moving image photographing mode of the integration filter during still image shooting mode is selected is selected by the selection means It is characterized by that.
[0012]
The background to devise this imaging device is as follows. Some recent video cameras have a function to shoot still images, but when shooting still images, the movement of the screen during pan / tilt is not a problem unlike when shooting movies. There is room for improving the camera shake correction performance by further lowering the cutoff frequency of the integral filter that generates the angular velocity displacement signal of the camera shake.
[0013]
Therefore, according to this imaging apparatus, when the photographer intends to shoot a still image, when the still image shooting mode is selected by the selection unit, the cutoff frequency of the integral filter is set to the moving image shooting mode by the switching unit. The frequency can be switched to a lower frequency than in the case of selection , and this improves the camera shake correction performance at the time of still image shooting.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing an example of a configuration of a part related to the present invention in a video camera to which an imaging apparatus according to claim 1 of the present invention is applied. This video camera has an electronic camera shake correction function, and includes an angular velocity sensor 11, an A / D converter 12, a microcomputer 21, a CCD driving timing generator 31, a zoom LSI 32, a digital signal processing LSI (video signal processing). Circuit for digital signal processing) 41, CCD image pickup device 51, lens 61, zoom position detector (not shown) for generating a signal indicating the focal length f of the lens 61 (signal indicating the zoom position), stationary subject mode / A normal mode selection unit 71 is provided.
[0015]
The stationary subject mode / normal mode selection unit 71 is an operation button attached to the surface of the casing of the video camera so that the photographer can select either the stationary subject mode or the normal mode. The selection unit 71 generates a signal Mode_A indicating which mode is selected and sends it to the microcomputer 21.
[0016]
The angular velocity sensor 11 is composed of two angular velocity sensors that detect camera shakes in the vertical and horizontal directions of the video camera as angular velocities. Angular velocity data Sgyro (vertical and horizontal angular velocity data) output from the angular velocity sensor 11 is oversampled by the A / D converter 12, and angular velocity sampling value data output from the A / D converter 12 at each oversampling timing. Ssamp is sent to the microcomputer 21.
[0017]
A signal indicating the focal length f of the lens 61 is also sent to the microcomputer 21. As will be described in detail later, the microcomputer 21 uses the signal Mode_A, the angular velocity sampling value data Ssamp, and the signal indicating the focal length f as information necessary for correcting the camera shake as the vertical direction control data SVtg and the vertical / horizontal data. Direction control data SVzoom is calculated. The vertical direction control data SVtg and the vertical / horizontal direction control data SVzoom are sent from the microcomputer 21 to the CCD driving timing generator 31 and the zoom LSI 32, respectively.
[0018]
The CCD drive timing generator 31 generates a drive pulse DP for driving the CCD image pickup device 51 based on the vertical direction control data SVtg and sends it to the CCD image pickup device 51.
The CCD imaging device 51 has an imaging area larger than the effective field angle by providing a margin area around the scanning area (effective field angle), and the vertical transfer CCD ( Among the charges read out (not shown), charges in the marginal area are transferred at high speed based on the drive pulse DP and discharged, thereby cutting out the effective angle of view in the vertical direction. On the other hand, among the charges read out to the vertical transfer CCD, the charges in the scanning region are converted into voltage signals (video analog signals) by an output unit (not shown) through a horizontal transfer CCD (not shown). This video analog signal is sent to the digital signal processing LSI 41.
[0019]
The digital signal processing LSI 41 generates a luminance signal Y and a color signal C based on a signal obtained by digitally converting the video analog signal, and sends it to the zoom LS32. The zoom LS 32 generates a luminance signal Y and a color signal C that have been subjected to camera shake correction in the vertical and horizontal directions based on the luminance signal Y and the color signal C and the vertical and horizontal direction control data SVzoom from the microcomputer 21 to generate digital signals. Returned to the processing LSI 41. The digital signal processing LSI 41 generates a video signal Y / C based on the shake-corrected luminance signal Y and the color signal C sent from the zoom LS 32 and sends them to a video signal recording system (not shown) of the video camera. .
[0020]
FIG. 2 is a functional block diagram illustrating an example of operations performed by the microcomputer 21 to calculate the vertical direction control data SVtg and the vertical / horizontal direction control data SVzoom.
The microcomputer 21 cuts the low-frequency component of the angular velocity sampling value data Ssamp from the A / D converter 12 by the high-pass filter 22, and uses the output signal Shpf of the filter 22 as a signal indicating the focal length f of the lens 61. The gain adjustment unit 23 adjusts the gain based on the signal and sends the output signal Sgain of the gain adjustment unit 23 to the integration filter 24.
[0021]
As shown in FIG. 3, the integration filter 24 is different depending on whether the signal Mode_A from the stationary subject mode / normal mode selection unit 71 indicates a normal mode or a stationary subject mode. A table in which the cutoff frequencies f1 and f2 are associated is provided. Here, f1 is a frequency determined based on the balance between the camera shake correction performance and the amount of back-back during pan / tilt, and f2 is a frequency determined lower than f1 in order to prioritize improvement of the camera shake correction performance It is.
The integration filter 24 refers to this table and integrates the output signal Sgain of the gain adjusting unit 23 with a cutoff frequency corresponding to each of the normal mode and the stationary subject mode, thereby generating a camera shake angular velocity displacement signal Sint. Is done.
[0022]
The microcomputer 21 performs gain and phase compensation on the angular velocity displacement signal Sint with the characteristic compensation filter 25, and uses the signal Sequ obtained with the gain and phase compensation in the SVtg / SVzoom calculation unit 26 with the vertical direction control data SVtg and the vertical / horizontal direction. Control data SVzoom is calculated.
[0023]
An example of the shooting operation with this video camera will be described as follows.
It is assumed that the photographer should select the normal mode with the still subject mode / normal mode selection unit 71 except when shooting without panning / tilting. Then, in the calculation shown in FIG. 2, the integration of the signal Sgain in the integration filter 24 is performed at the cutoff frequency f1.
[0024]
On the other hand, the photographer should select the still subject mode in the still subject mode / normal mode selection unit 71 when attempting to take a picture without pan / tilt. Then, the integration of the signal Sgain by the integration filter 24 is performed by switching the cutoff frequency to f2 lower than f1.
[0025]
FIG. 4 shows an example of gain characteristics of the integration filter 24 (characteristics of the signal Sint with respect to the signal Sgain in the frequency domain). In the normal mode, when the cutoff frequency is f1, the signal Sgain is integrated only in the frequency region of f1 or higher, and as a result, camera shake correction is performed only in this frequency region.
[0026]
On the other hand, in the still subject mode, when the cutoff frequency is f2, the signal Sgain is integrated in the frequency region of f2 or higher, and as a result, camera shake correction is performed in this frequency region. Accordingly, since the camera shake correction is performed even in the low frequency region from f2 to f1 where the camera shake correction is not performed in the normal mode, the camera shake correction performance is improved as compared with the normal mode.
[0027]
In this way, according to this video camera, pan / tilt is involved as compared with a conventional video camera in which the cutoff frequency of the integral filter is determined as a fixed value in consideration of the camera shake correction performance and the amount of the back swing. Camera shake correction performance when shooting is not improved.
[0028]
Next, FIG. 5 is a block diagram showing an example of the configuration of a part related to the present invention in a video camera to which an imaging apparatus according to claim 2 of the present invention is applied. In FIG. Are denoted by the same reference numerals, and redundant description is omitted.
This video camera has a still image shooting function, and instead of the still subject mode / normal mode selection unit 71 in FIG. 1, one of a video shooting mode and a still image shooting mode is set for the photographer. A moving image shooting mode / still image shooting mode selection unit 72, which is an operation button for selection, is provided. The selection unit 72 generates a signal Mode_B indicating which mode is selected and sends it to the microcomputer 21.
[0029]
FIG. 6 is a functional block diagram showing an example of operations performed by the microcomputer 21 for calculating the vertical direction control data SVtg and the vertical / horizontal direction control data SVzoom in the video camera of FIG. The same parts are denoted by the same reference numerals, and redundant description is omitted.
[0030]
In this video camera, as shown in FIG. 7, the signal Mode_B from the moving image shooting mode / still image shooting mode selection unit 72 indicates either the moving image shooting mode or the still image shooting mode. A table is provided in which different cut-off frequencies f1 and f3 are associated with each other depending on whether it is a thing. As described above, f1 is a frequency determined based on the balance between the camera shake correction performance and the amount of back-back during pan / tilt, and f3 is determined to be lower than f1 in order to prioritize the improvement of the camera shake correction performance. Is the frequency.
[0031]
The integration filter 24 refers to this table and integrates the output signal Sgain of the gain adjusting unit 23 with the cut-off frequency corresponding to each of the moving image shooting mode and the still image shooting mode, so that the angular velocity displacement signal Sint of the camera shake. Is generated.
[0032]
Next, an example of photographing operation with this video camera will be described.
It is assumed that the photographer should select the moving image shooting mode in the moving image shooting mode / still image shooting mode selection unit 72 when shooting a moving image. Then, in the calculation shown in FIG. 2, the integration of the signal Sgain in the integration filter 24 is performed at the cutoff frequency f1.
[0033]
On the other hand, the photographer should select the still image shooting mode in the moving image shooting mode / still image shooting mode selection unit 72 when shooting a still image. Then, the integration of the signal Sgain by the integration filter 24 is performed by switching the cut-off frequency to f3 lower than f1.
[0034]
FIG. 8 shows an example of the gain characteristic of the integration filter 24. In the moving image shooting mode, when the cutoff frequency is f1, the signal Sgain is integrated only in the frequency region of f1 or higher, and as a result, camera shake correction is performed only in this frequency region.
[0035]
On the other hand, in the still image shooting mode, when the cutoff frequency is f3, the signal Sgain is integrated in the frequency region of f3 or higher, and as a result, camera shake correction is performed in this frequency region. Accordingly, since the camera shake correction is performed even in the low frequency region from f3 to f1 where the camera shake correction is not performed in the normal mode, the camera shake correction performance is improved as compared with the moving image shooting mode.
[0036]
In this way, according to this video camera, it is more effective at the time of still image shooting than the conventional video camera that determines the cutoff frequency of the integral filter as a fixed value in consideration of the camera shake correction performance and the amount of the swing back. Image stabilization performance is improved.
[0037]
Of the above examples, in the examples shown in FIGS. 1 to 4, the cut-off frequency of the integration filter 24 is switched to a low frequency only when the still subject mode is selected, so that shooting without pan / tilt is performed. In the example shown in FIGS. 5 to 8, the cutoff frequency of the integration filter 24 is switched to a low frequency only when the still image shooting mode is selected. Only try to improve camera shake correction performance.
[0038]
However, as another example, in a video camera having a still image shooting function, in addition to the moving image shooting mode / still image shooting mode selection unit 72 of FIG. In addition, by providing a table in which the cut-off frequencies f1, f3, and f2 are associated with each of the moving image shooting mode, the still image shooting mode, and the still subject shooting mode, shooting with panning and tilting with one video camera is possible. The camera shake correction performance may be improved both during shooting and during still image shooting.
[0039]
In each of the above examples, the present invention is applied to a video camera having an electronic camera shake correction function. However, the present invention may be applied to a video camera having an optical camera shake correction function.
In each of the above examples, the present invention is applied to a video camera. However, the present invention may be applied to other appropriate imaging devices having a camera shake correction function.
Further, the present invention is not limited to the above-described embodiments, and various other configurations can be taken without departing from the gist of the present invention.
[0040]
【The invention's effect】
As described above, according to the imaging apparatus of the first aspect of the present invention, it is possible to improve the camera shake correction performance when shooting without panning / tilting as compared with the related art.
In addition, according to the image pickup apparatus of the second aspect of the present invention, it is possible to improve the camera shake correction performance when taking a still image as compared with the related art.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a configuration of a video camera to which an imaging apparatus according to the present invention is applied.
FIG. 2 is a functional block diagram illustrating an example of operations performed by the microcomputer of FIG.
FIG. 3 is a diagram illustrating an example of a table included in the integration filter of FIG. 2;
4 is a diagram illustrating an example of gain characteristics of the integration filter of FIG. 2;
FIG. 5 is a block diagram showing another example of the configuration of a video camera to which the imaging apparatus according to the present invention is applied.
6 is a functional block diagram showing an example of operations performed by the microcomputer of FIG.
7 is a diagram illustrating an example of a table included in the integration filter of FIG. 6;
8 is a diagram illustrating an example of gain characteristics of the integration filter of FIG. 6;
[Explanation of symbols]
11 angular velocity sensor, 12 A / D converter, 21 microcomputer, 22 high-pass filter, 23 gain adjustment unit, 24 integral filter, 25 characteristic compensation filter, 26 SVtg / SVzoom calculation unit, 31 CCD drive timing generator, 32 zoom LSI, 41 Digital signal processing LSI, 51 CCD image sensor, 61 Lens, 71 Still subject mode / normal mode selection unit, 72 Movie shooting mode / still image shooting mode selection unit

Claims (2)

A high-pass filter that cuts a low-frequency component of a camera shake detection output of the imaging apparatus; and an integration filter that generates an angular velocity displacement signal of a camera shake by integrating an output signal of the high-pass filter, and the angular velocity In the imaging apparatus configured to correct the camera shake based on the displacement signal ,
A selection means for selecting one of a stationary subject mode for shooting without displacing the imaging device and a normal mode for shooting by displacing the imaging device ;
An imaging apparatus comprising: switching means for switching a cut-off frequency of the integration filter when the stationary subject mode is selected by the selection means to a lower frequency than when the normal mode is selected. . A high-pass filter that has a still image shooting function and cuts the low-frequency component of the camera shake detection output of the imaging device, and an integration that generates an angular velocity displacement signal of camera shake by integrating the output signal of the high-pass filter In an imaging device having a filter and correcting the camera shake based on the angular velocity displacement signal ,
A selection means for selecting either the still image shooting mode or the movie shooting mode ;
Switching means for switching the cut-off frequency of the integration filter when the still image shooting mode is selected by the selection means to a lower frequency than when the moving image shooting mode is selected. Imaging device.

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