JP2007140064A - Optical equipment with image blur correcting function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate unnecessary image blur correcting operation and viewing angle change so as not to give feeing of incompatibility to a photographer, regarding optical equipment with an image blur correcting function, capable of photographing while switching moving image photographing and still image photographing. <P>SOLUTION: Regarding the optical equipment with a switching means for switching the moving image photographing and the still image photographing and the image blur correcting means for reducing the blurring in a photographed image, whether the optical equipment is held by hands or fixed is detected. In the case the equipment is in a fixed state, a centering processing by the image blur correcting means to move the optical path to nearly the center position of the optical axis of a photographing optical system for the optical equipment is carried out so as to be suitable for the moving image photographing or the still image photographing. The centering processing is carried out at the moving image photographing for a time longer than that at the still image photographing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical apparatus (photographing apparatus) with an image blur correction function such as a video camera.

With downsizing of video cameras and higher magnification of optical systems, camera shake is a major cause of lowering the quality of captured images. In view of this, various photographing apparatuses with an image blur correction function for correcting camera shake have been proposed.
When using an imaging device with an image shake correction function fixed with a tripod or the like, the shake correction optical system is centered at a predetermined position such as the optical axis position in order to prevent malfunction of the shake correction. It is common to do. This is because the stationary output of a shake detection sensor (for example, a gyro sensor or an acceleration sensor) fluctuates at a low frequency of several Hz or less due to individual variations and operating temperatures, and the stationary fluctuation is erroneously corrected. There is a purpose to prevent. The detection of the support state includes a method of providing a sensor at a connection part for attaching a tripod, a method of determining the support state by monitoring the output of the shake detection sensor, and the like.
As a centering method at the time of detecting a support state, a method for prohibiting centering according to a photographing state such as a shake amount applied to the apparatus, a shutter speed, and a focal length has been conventionally proposed (for example, see Patent Document 1).
JP-A-9-212518

In recent years, with the advancement of image processing technology, it has become possible to shoot both moving images and still images with high image quality with a single shooting device.
The present inventor has found that in a photographing apparatus that can be used by switching between moving image photographing and still image photographing, it is necessary to change the centering after detecting the support state in accordance with each photographing mode. At the time of moving image shooting, it is desirable to reduce a sudden change in the angle of view due to the centering operation during shooting and to be gently held at a predetermined position such as the optical axis. Also, during still image shooting, in order not to miss a shooting scene, it must be held at a predetermined position immediately after detection of the support state.
Accordingly, an object of the present invention is to provide an optical apparatus with an image shake correction function that optimizes the centering operation during moving image shooting and still image shooting.

  An optical apparatus for solving the above-described problems includes a switching unit for switching between a moving image shooting mode and a still image shooting mode, an image shake correcting unit for reducing shake of a captured image, and the optical device being fixed. Support state detecting means for detecting this. And a centering means for moving the optical path by the image shake correction means to a substantially optical axis center position of the photographing optical system of the optical equipment when the support state detection means determines that the optical equipment is in a fixed state. Is provided. In the optical apparatus with an image shake correction function, the present invention further includes a centering control unit that changes a control mode of the centering unit in accordance with the photographing mode set by the switching unit. .

  According to the present invention, it is possible to eliminate unnecessary centering and a sudden change in the angle of view by changing the centering control after detecting the support state in each of the moving image shooting mode and the still image shooting mode. Thereby, it becomes possible to perform favorable imaging | photography in each imaging | photography mode, without giving a user discomfort.

Further objects or other features of the present invention will be shown in the embodiments described below with reference to the accompanying drawings.
Preferred embodiments of the present invention will be described below in detail based on examples shown in the accompanying drawings.
[Example 1]
FIG. 1 shows the configuration of a video camera with an image blur correction function which is an optical apparatus (photographing apparatus) according to an embodiment of the present invention.
In FIG. 1, 100 is a fixed front lens unit, 101 is a zoom lens unit that moves in the optical axis direction and performs zooming, 103 is a fixed lens unit, and 104 is a focus lens that moves in the optical axis direction and performs focus adjustment. Is a unit. Reference numeral 102 denotes an aperture for adjusting the amount of light.
Reference numeral 126 denotes a variable apex angle prism for performing optical image blur correction, which is configured by sealing a transparent elastic body or inert liquid having a high refractive index between flat glass plates arranged opposite to each other. The variable apex angle prism 126 can displace the optical path by tilting the flat glass.

  A light beam from a subject (not shown) passes through the variable apex angle prism 126, the lens units 100, 101, 103, 104, and the aperture 102, and the light receiving surface of the image sensor (photoelectric conversion element) 105 such as a CCD sensor or a CMOS sensor. Image above. In the imaging element 105, the photoelectrically converted charge is accumulated, and the charge is read at a predetermined timing. The signal output from the image sensor 105 is sent to the video signal processing circuit 106. The video signal processing circuit 106 performs various processes such as predetermined amplification and gamma correction on the output signal from the image sensor 105 to generate a video signal. The video signal is output to a display device (not shown) (liquid crystal display panel or the like). The control CPU 120 is an arithmetic processing unit that controls the camera and lens, such as control of the video signal processing circuit 106 and shake correction control.

  Reference numeral 111 denotes a gyro sensor that physically or mechanically detects vibration of the photographing apparatus. Reference numeral 112 denotes a DC cut filter that blocks the direct current component of the output signal from the gyro sensor 111 and passes only the vibration component. The cut-off frequency of the DC cut filter 112 is about 0.1 Hz. An amplifier 113 amplifies the angular velocity signal output from the DC cut filter 112 to a required level. The angular velocity signal amplified by the amplifier 113 is converted from an analog signal to a digital signal by an AD converter 114 in the control CPU 120 and input to a variable high-pass filter (hereinafter abbreviated as HPF) 115. The variable HPF 115 is used to obtain a desired frequency band in the input angular velocity signal. For example, when the cut-off frequency of the variable HPF 115 is about 0.1 Hz, a shake signal such as hand shake or body shake is passed. When the cut-off frequency is a sufficiently high frequency of 100 Hz or more, the shake signal is not passed, the reference potential of the gyro sensor 111 is output, and the shake correction system is in a centered state. The angular velocity signal output from the variable HPF 115 is input to the phase / gain compensation unit 116, phase compensation and gain setting are performed, and the resultant signal is sent to the integration processing unit 117. The signal that has passed through the integration processing unit 117 becomes an angular displacement signal, and becomes a target angular displacement signal for performing image blur correction or centering.

  The position indicating the apex angle or the optical axis deflection angle of the variable apex angle prism 126 is detected by the encoder 107. The detection signal is converted into a position signal by the signal processing circuit 108, converted into a digital signal by the AD converter 121, and fed back to the subtractor 118. The output of the subtractor 118 indicates an error between the target angular displacement signal of the variable apex angle prism 126 and the actual position signal of the variable apex angle prism 126. A signal corresponding to the error amount is compensated for the phase and gain by the phase / gain compensation unit 119, and is input to the drive circuit 110 as a shake correction control signal. The actuator 109 drives the variable apex angle prism 126 based on the drive signal from the drive circuit 110 to perform shake correction. The image blur correction ON / OFF switch 127 is a switch that is operated by the user to switch whether or not image blur correction is performed.

  The support state detection unit 123 detects whether or not the photographing apparatus is fixed to a tripod or the like. The block diagram of FIG. 1 shows a method of detecting the support state from the angular velocity signal after AD conversion of the output of the gyro sensor 111 and the angular displacement signal. The support state is detected by detecting the amplitude of the angular velocity signal, the amplitude of the angular displacement signal, and the frequency of the angular displacement signal. When the support state is detected, the centering processing unit 124 changes the cutoff frequency of the variable HPF 115 and performs a centering operation. At that time, the switching information of the moving image / still image switching SW 125 is monitored, and the centering process is changed in each photographing mode. These detailed operations will be described later with reference to flowcharts.

  FIG. 2 shows an example of an operation flow of the support state detection unit 123. This detection example is a method of detecting the support state of the imaging apparatus from the amplitude values of the angular velocity signal and the angular displacement signal. The operation flow shown in FIG. 2 is repeated for each vertical synchronization frequency of the image signal (for example, 60 Hz for NTSC) and every calculation cycle of the control CPU. In the following, “Step XXX” indicating the process step number is referred to as “#XXX”.

(# 301) The control CPU 120 determines whether the amplitude of the angular velocity signal measured by the gyro sensor 111 and AD converted by the AD converter 114 is equal to or smaller than a predetermined value. If it is larger than the predetermined value, it is determined that the photographing apparatus is not in a fixed state but is in a shake state, and the process proceeds to # 307. If it is equal to or smaller than the predetermined value, the process proceeds to # 302. Here, the threshold value of the amplitude must be larger than the fluctuation of the gyro sensor output at the time of stationary and smaller than the amplitude of the camera shake.
(# 302) The support state detection counter 1 is counted up. This counter is counted up every time the amplitude value of the angular velocity signal at # 301 is equal to or smaller than a predetermined value.

(# 303) The control CPU 120 determines whether the amplitude of the angular displacement signal that is the output of the integration processing unit 117 is equal to or smaller than a predetermined value. If it is larger than the predetermined value, it is determined that the photographing apparatus is not in a fixed state but is in a shake state, and the process proceeds to # 307. If it is equal to or smaller than the predetermined value, the process proceeds to # 304. The threshold value of the amplitude here must be larger than the fluctuation of the angular displacement at the time of stationary and smaller than the amplitude of the camera shake similarly to the processing in # 301.
The reason for using two types of signals of angular velocity and angular displacement for the determination is to prevent erroneous detection due to momentary vibration such as minute noise of the detection signal itself or switch operation of the apparatus.
(# 304) The support state detection counter 2 is counted up. This counter is counted up whenever the amplitude of the angular velocity signal at # 301 is less than or equal to a predetermined value and the amplitude of the angular displacement signal at # 303 is less than or equal to a predetermined value.

(# 305) It is determined whether each of the support state detection counters 1 and 2 has reached a predetermined count value or more. A large count value means that the output of the angular velocity or angular displacement signal is stable and it can be determined that the photographing apparatus is fixed. If the count value is less than or equal to the predetermined count value, the process is repeated again from # 301. When the count value is equal to or greater than the predetermined count value, the process proceeds to # 306.
(# 306) The support state detection flag is set. The centering processing unit 124 checks this flag to determine whether or not it is in the support state. If the flag is set, the centering operation is performed. Details will be described later.

(# 307) If it is determined in # 301 or # 303 that the shake is large, that is, it is not in the support state, the support state detection counters 1 and 2 are cleared to zero, and the process proceeds to the next step.
(# 308) The support state detection flag is cleared, and the process is repeated again from # 301.

As described above, the support state detection operation shown in FIG. 2 is executed at a cycle determined in the control CPU 120. The support state can be determined by checking whether the support state detection flag is set or cleared.
In FIG. 2, it is determined whether or not the photographing apparatus is fixed by observing the angular velocity and the angular displacement. As another method, a detector is provided at the tripod mounting part, and the support state of the device is determined from the output of the detector, or the fluctuation frequency of the angular displacement signal is measured, and the support state of the device is determined from this frequency. There is a way.

  Next, the details of the centering process of the photographing apparatus with an image blur correction function according to an embodiment of the present invention will be described with reference to FIG. The centering operation in the present embodiment is realized by gradually increasing the cutoff frequency of the variable HPF 115 in increments of the set change frequency. By increasing the cut-off frequency, the shake component of the angular velocity signal is cut and a reference potential (centering signal) is obtained. As a result, the target angular displacement signal makes the shake correction optical system a predetermined position such as the optical axis position, so that centering is possible.

(# 401) The centering processing unit 124 in the control CPU 120 checks the support state detection flag shown in FIG. 2 and determines whether or not it is in the support state. If it is determined to be in the support state, the process proceeds to # 402, and if it is not in the support state, the process ends.
(# 402) It is determined whether the moving image shooting mode or the still image shooting mode. For the determination, a moving / still image switching SW signal is used. For example, the SW signal High is determined in advance so as to select the moving image shooting mode and Low is set to the still image shooting mode selection. If the user has selected the moving image shooting mode, the process proceeds to # 403, and if not (that is, the still image shooting mode), the process proceeds to # 404.

(# 403) The change frequency of the HPF cutoff frequency in the moving image shooting mode is set. For example, the change frequency is set to several Hz, and the cut-off frequency is changed in # 405 according to the change frequency set here.
(# 404) The change frequency of the HPF cutoff frequency in the still image mode is set. For example, the change frequency is set to several tens of Hz, and the cut-off frequency is changed in # 405 according to the change frequency set here.

(# 405) The cutoff frequency of the variable HPF 115 is changed. Specifically, the cutoff frequency is increased by a change frequency set in # 403 or # 404 in a predetermined cycle. As the cutoff frequency increases, the output of the variable HPF 115 approaches the reference potential (that is, the centering position). The speed of approaching the reference potential varies depending on the change frequency set in # 403 or # 404. Therefore, the time until centering can be changed in each mode.
(# 406) It is determined whether the centering is completed. For example, the cutoff frequency increased by changing in # 405 is monitored, and it is determined that the centering is completed when the cutoff frequency becomes 100 Hz or higher. Until completion, the change of the cut-off frequency in # 405 and the determination in # 406 are repeated.

  In the process shown in FIG. 3, a change value of the cut-off frequency suitable for each shooting mode is set in the process of # 403 or # 404. Since the time to centering can be adjusted by changing (increasing) the cut-off frequency at the set change frequency, centering in the support state can be controlled in accordance with the photographing mode.

Next, the control method of the centering operation of this embodiment will be described using the waveforms shown in FIG. FIG. 4 shows a waveform of angular displacement which is an output of the integration processing unit 117 of the photographing apparatus. When the control CPU 120 detects the support state by the method shown in FIG. 2, the centering operation is started. In the centering period, the cutoff frequency of the variable HPF 115 is changed at the frequency set in each shooting mode. Therefore, the position indicated by the angular displacement signal gradually moves to a predetermined position (for example, the optical axis position), and centering is performed.
In the moving image shooting mode, control is performed so that the change of the angular displacement signal during the centering period becomes gentle. This is because a sudden change in the angle of view is eliminated even during shooting, and the photographer is not discomforted. Further, in the still image shooting mode, by controlling the change of the angular displacement signal more rapidly than in the case of moving images, it is possible to eliminate the unnecessary change in the angle of view after the tripod is attached and to perform shooting immediately.

[Example 2]
FIG. 5 shows an operation flow of the photographing apparatus with an image blur correction function according to the second embodiment of the present invention.
(# 501) The centering processing unit 124 in the control CPU 120 checks the support state detection flag shown in FIG. 2 and determines whether or not it is in the support state. If it is determined to be in the support state, the process proceeds to # 502, and if it is not in the support state, the process ends.
(# 502) It is determined whether the mode is a moving image shooting mode or a still image shooting mode. For the determination, a moving / still image switching SW signal is used. For example, the SW signal High is determined in advance so as to select the moving image shooting mode and Low is set to the still image shooting mode selection. If the user has selected the moving image shooting mode, the process proceeds to # 503, and if not (that is, the still image shooting mode), the process proceeds to # 506.

(# 503) The change frequency of the HPF cutoff frequency in the moving image shooting mode is set. For example, the change frequency is set to several Hz, and the cut-off frequency is changed in # 504 according to the change frequency set here.
(# 504) The cutoff frequency of the variable HPF 115 is changed. Specifically, the cutoff frequency is increased for each change frequency set in # 503 in a predetermined cycle. As the cutoff frequency increases, the output of the variable HPF 115 approaches the reference potential (that is, the centering position).
(# 505) It is determined whether the centering is completed. For example, an increase in frequency is monitored by changing the cutoff frequency performed in # 504, and it is determined that centering is completed when the frequency becomes 100 Hz or higher. Repeat the determination until complete.
(# 506) If the support state is detected in # 501 and it is determined in # 502 that the still image shooting mode is set, the image blur correction is turned off without performing the centering operation.

  In the second embodiment, in the case of still image shooting, the centering operation is not performed and the image blur correction itself is stopped. By performing such control, it is possible to eliminate an unnecessary change in the angle of view after the tripod is mounted and to perform shooting immediately. Further, since image blur correction is not performed, power consumption can be suppressed.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.
For example, in the present embodiment, the image blur correction using the variable apex angle prism has been described, but the same centering control can be performed by the image blur correction using a shift lens that can move horizontally and vertically with respect to the optical axis.
Further, the present invention can be applied not only to an optical image shake correction operation but also to a centering control by a method of performing shake correction (electronic image stabilization) using image data in a video processing circuit.

It is a block diagram which shows the structure of the imaging device which concerns on one Example of this invention. It is a flowchart which shows the support state detection operation | movement of the imaging device which concerns on Example 1 of this invention. 6 is a flowchart illustrating a centering operation of the photographing apparatus according to the first embodiment of the present invention. It is a figure which shows the angular displacement signal waveform of the imaging device which concerns on Example 1 of this invention. It is a flowchart which shows the centering operation | movement of the imaging device which concerns on Example 2 of this invention.

Explanation of symbols

100, 101, 103, 104: Lens unit 105: Image sensor 111: Gyro sensor 115: Variable HPF
117: Integration processing unit 120: Control CPU
123: Supporting state detection unit 124: Centering processing unit 125: Moving image / still image switching switch 126: Variable vertical angle prism

Claims (4)

An optical apparatus comprising a switching means for switching between a moving image shooting mode and a still image shooting mode, and an image shake correction means for reducing shake of a shot image,
A support state detection unit that detects that the optical device is fixed; and the support state detection unit that determines that the optical device is in a fixed state, the optical path of the image shake correction unit is changed to the optical path In an optical instrument comprising centering means for moving to a substantially optical axis center position of the photographing optical system of the instrument,
An optical apparatus with an image blur correction function, comprising centering control means for changing the control of the centering means in accordance with the photographing mode set by the switching means.   When the moving image shooting mode is selected by the switching unit, the centering control unit causes the centering operation to be performed in the first control time from the centering start to the end, and the still image shooting mode is selected by the switching unit. The optical apparatus with an image blur correction function according to claim 1, wherein the centering operation is performed in a second control time shorter than the first control time.   The image blur correction unit includes a unit that detects an acceleration of image blur, a high-pass filter that filters the acceleration, an integration unit that integrates an output of the high-pass filter and outputs a displacement of the image blur, and an imaging optical system Means for displacing the optical path and means for detecting the amount of displacement of the optical path displacing means, feedback control of the amount of displacement of the optical path displacing means with reference to the output of the integrating means, and the centering control means comprises the high pass 3. The optical apparatus with an image blur correction function according to claim 2, wherein the centering is performed by increasing a cutoff frequency of a filter at a speed corresponding to the first or second control time. When the moving image shooting mode is selected by the switching unit, the centering control unit performs a centering operation, and when the still image shooting mode is selected by the switching unit, the image blur is performed without performing the centering operation. The optical apparatus with an image blur correction function according to claim 1, wherein the operation of the correction unit is stopped.

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