JP3548308B2 - Imaging device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image pickup apparatus, and more particularly to correction of blurring (sometimes referred to as blurring).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, video cameras have been automated and multifunctional in all aspects, such as AE (auto exposure) and AF (auto focus), so that good shooting can be easily performed.
[0003]
Focusing on the recent downsizing of video cameras and the increase in the magnification of optical systems, camera shake has become a major cause of degrading the quality of captured images. Various types of image pickup apparatuses have been proposed.
[0004]
FIG. 5 shows an example of a configuration of a main part of a conventional imaging apparatus with a shake correction function. In FIG. 1, reference numeral 1 denotes an angular velocity detector including an angular velocity sensor such as a vibrating gyroscope, which is attached to an imaging device with a shake correction function such as a camera. Reference numeral 2 denotes a DC cut filter that cuts off a DC component of the angular velocity signal output from the angular velocity detector 1 and passes only an AC component, that is, a vibration component. As the DC cut filter, a high-pass filter (hereinafter, referred to as HPF) that blocks a signal in a predetermined band may be used.
[0005]
Reference numeral 3 denotes an amplifier for amplifying the angular velocity signal output from the DC cut filter 2 to an appropriate level (a level at which a required detection sensitivity is obtained).
[0006]
Reference numeral 4 denotes an A / D converter that converts the angular velocity signal output from the amplifier 3 into a digital signal. Reference numeral 5 denotes a high-pass filter (HPF) that blocks a low-frequency component of the output of the A / D converter 4, and an arbitrary band. Has the function of changing the characteristics. Reference numeral 6 denotes an integrator that integrates the output (angular velocity signal) of the HPF 5 and outputs an angular displacement signal, and has a function of changing characteristics in an arbitrary band. Reference numeral 7 denotes a pan / tilt determination circuit which determines panning / tilting from an angular velocity signal and an integral signal of the angular velocity signal output from the integrator circuit 6, that is, an angular displacement signal. The pan / tilt determination circuit 7 will be described later based on the levels of the angular velocity signal and the angular displacement signal. Perform panning and tilting control. Reference numeral 8 denotes a D / A converter that converts the output of the angular displacement signal into an analog signal and outputs the analog signal. The A / D converter 4, the HPF 5, the integrator 6, the pan / tilt determination circuit 7, and the D / A converter 8 are constituted by, for example, a microcomputer COM. Reference numeral 9 denotes a drive circuit for driving the image correcting means in the subsequent stage so as to suppress blurring based on the angular displacement signal output from the microcomputer. Numeral 10 denotes image correcting means, which optically shifts the optical axis to reduce blurring. Canceling optical correction means are used.
[0007]
Here, the operation of the pan / tilt determination circuit 7 will be described in detail. The angular velocity signal output from the A / D converter 4 and the angular displacement signal output from the integration circuit 6 are input, and even if the angular velocity is equal to or more than a predetermined threshold or the angular velocity is within a predetermined threshold, When the angular displacement signal obtained by integrating the angular velocity signal is equal to or larger than a predetermined threshold value, it is determined that the panning or the tilting is performed. In such a case, the low frequency cutoff frequency of the HPF 5 is shifted to the high frequency side, The characteristic is changed so that the shake correction system does not respond to the low frequency, and when panning and tilting are detected, the correction position of the image correction means is gradually centered at the center of the movement range. Then, control is performed such that the time constant of the integration characteristic of the integrator 6 is shifted in a shorter direction, and the value stored in the integrator is set to a reference value (a value that can be taken in a state where no fluctuation is detected) (panning Performs tilting control).
[0008]
During this time, the angular velocity signal and the angular displacement signal are still detected, and when the panning and the tilting are completed, the low-frequency cutoff frequency is lowered again, and the time constant of the integration characteristic is lengthened and the camera shakes. An operation of expanding the correction range is performed, and the process exits from panning and tilting control.
[0009]
This operation will be described with reference to the flowchart of FIG.
# 01 This is the start of this flow, which is repeatedly started at a predetermined timing.
[0010]
# 02 Converts the amplified angular velocity signal from an analog amount to a digital value that can be handled in the microcomputer.
[0011]
# 03 The HPF is calculated using the previously prepared cutoff frequency (fc) value.
[0012]
# 04 Integral calculation is performed using the value of the previously prepared time constant.
[0013]
# 05 The integration result, that is, the angular displacement signal is converted into an analog amount and output.
[0014]
# 06 It is determined whether the angular velocity signal is equal to or greater than a predetermined threshold.
[0015]
# 07 It is determined whether or not the integral value is equal to or greater than a predetermined threshold.
[0016]
Here, even if the angular velocity signal is equal to or greater than a predetermined threshold value, or if the integral value is equal to or greater than the predetermined threshold value, the panning and tilting states are determined and the process proceeds to # 08, even if the angular velocity signal does not satisfy the predetermined threshold value. If both the angular velocity signal and the integral value are less than the predetermined threshold value, it is determined that the control state is the normal control state or the panning and tilting end states, and the process proceeds to # 10.
[0017]
# 08 The value of the cutoff frequency used for the HPF calculation is made higher than the current value by a predetermined value, and the attenuation rate of the low frequency signal is made larger than the current value.
[0018]
# 09 The value of the time constant used for the integration operation is shortened by a predetermined value from the current value so that the angular displacement output approaches the reference value.
[0019]
# 10 The value of the cutoff frequency used for the HPF calculation is made lower than the current value by a predetermined value, and the attenuation rate of the low-frequency signal is made smaller than the current value.
[0020]
# 11 The value of the time constant used for the integration operation is made longer than the current value by a predetermined value to increase the integration effect.
[0021]
# 12 End of processing.
[0022]
Next, an example of the image correction means 10 in the conventional example is shown in FIG.
[0023]
The figure uses a variable apex prism 100 in particular, uses a voice coil type driving device 110 as a driving system, detects angular displacement by an encoder 120, and feeds it back to the driving system to control the driving amount. This is a control system that forms a closed loop.
[0024]
The variable apex prism 100 will be described in detail. Reference numerals 101 and 101 ′ shown in FIG. 1 denote flat glass placed opposite to each other, and 102 denotes a transparent high refractive index (refractive index n) inert liquid (or elastic liquid). And 103, a sealing material for elastically sealing the high-refractive liquid 102 from the outer periphery with a resin film or the like; 104, incident perpendicularly to the flat glass 101 and transmitted through the high-refractive liquid 102 and the flat glass 101 '. It shows an optical path of light.
[0025]
FIG. 7A shows a state in which the flat glasses 101 and 101 ′ are held in parallel, and the optical path 104 is incident on the flat glass 101 at right angles, passes through the high-refractive-index liquid 102, and is perpendicular to the flat glasses 101 ′. Inject.
[0026]
FIG. 2B shows a state in which the plane glass 101 ′ is inclined by the voice coil type driving device 110, and corresponds to a state in which the optical axis is shifted.
[0027]
In this state, an optical prism is formed by the flat glasses 101 and 101 'and the high-refractive-index liquid 102, so that light incident on the flat glass 101 at right angles is emitted from the flat glass 101' in FIG. The optical path 104 can be changed as shown.
[0028]
In FIG. 2B, the passing state of the incident light beam 104 'when one flat glass 101' of the variable apex angle prism 100 is rotated by an angle σ with respect to the flat glass 101 will be further described. As shown in the figure, the light beam 104 'incident on the flat glass 101 is deflected by an angle φ = (n-1) σ and emitted according to the same principle as the wedge prism. That is, the optical axis 104 'is decentered (deflected) by the angle. Note that σ corresponds to the vertex angle of the prism as is apparent from the figure. n is a refractive index, which is close to the refractive index of glass.
[0029]
A blur correction operation using the variable apex angle prism 100 will be described with reference to FIG. In the figure, 101'-A and 101'-B are the above-mentioned flat glass, 104 and 104 'are optical paths, 150 is an image pickup optical system, 161 is an image pickup device which photoelectrically converts the formed light and outputs it as an electric signal. , 162 are signal processing circuits for converting electric signals of the image sensor 161 into video signals such as NTSC, for example, and 13 is a recording device for recording video signals.
[0030]
When the flat glass 101'-A is parallel as shown in the figure, the optical path is linearly connected to the image plane as shown at 104, but when the optical path is tilted as shown at 101'-B The optical path changes as shown by 104 ', and it becomes possible to optically correct the movement of the subject image, that is, the image blur due to the shaking of the image pickup apparatus.
[0031]
Next, returning to FIG. 7, the driving device, that is, the driving actuator 110 will be described. Reference numeral 111 denotes a yoke, 112 denotes a magnet, 113 denotes a coil, and 114 denotes a driving torque transmitting arm. A voice coil type actuator capable of changing the apex angle of the apex angle prism 100 is configured.
[0032]
Further, an angular displacement encoder 120 is provided to detect the inclination of the variable apex angle prism. Reference numeral 121 denotes a slit for detecting the angular displacement of the variable apex angle prism 100. It rotates through 114 and displaces its position. 122 is a light emitting diode for detecting the position of the slit 121, 123 is a PSD (Position Sensing Detector: incident light spot position detection sensor using the surface resistance of the photodiode), and the PSD 123 is a light emitting diode 122 and a light emitting diode. An encoder that detects the angular displacement of the apex angle of the variable apex angle prism 100 by detecting the displacement is configured.
[0033]
The light flux whose optical path has been changed by the variable apex angle prism 100 is imaged on the imaging surface of the imaging element 161 through the imaging optical system 150 shown in FIG.
[0034]
Although not shown in FIG. 7 for convenience of explanation, there is a drive actuator, an encoder, and a control device having the same function at right angles to the drive direction of the variable apex angle prism 100. This enables vertical, horizontal, and vertical blur correction.
[0035]
Next, the basic configuration and operation of a control circuit that drives and controls the variable apex angle prism 100 will be described with reference to the block diagram of FIG. In the figure, 100 is a variable apex prism, 131 is an amplifier, 132 is a driver for driving an actuator, 110 is a voice coil type actuator for driving the variable apex prism described above, and 120 is the apex angle displacement of the variable apex prism. Is an adder that adds the control signal 133 for blur correction output from the microcomputer CMO and the output signal of the angular displacement encoder 120 with opposite polarities. With this configuration, the control system operates so that the shake correction control signal 133 output from the microcomputer COM and the output signal of the angular displacement encoder 120 become equal, and as a result, the output of the encoder 120 becomes the control signal 133. By driving the variable apex angle prism 100 so as to match, the variable apex angle prism 100 is controlled to a position (apex angle) designated by the microcomputer COM.
[0036]
[Problems to be solved by the invention]
However, when the optical correction means shown in the above-mentioned conventional example is used, optical spectroscopy (spectral dispersion) occurs to a greater or lesser extent when optical correction is performed, and the correction amount of the correction optical system increases. Color noise (color misregistration) occurs at the outline of the captured image.
[0037]
In particular, in the variable apex angle prism in which the flat glass and the high refractive index liquid are combined as described in the above-mentioned conventional example, when the optical axis is displaced, the spectrum becomes remarkable.
[0038]
In moving images of a conventional video camera or the like, the movement of the correction optical system is performed substantially symmetrically with respect to the center of correction (optical axis) in the horizontal and vertical directions. Was not a big problem.
[0039]
However, with the recent digitization of imaging devices and recording devices, devices for recording and reproducing moving images and still images with the same system have been proposed.
[0040]
Of course, such a system is also going to adopt a blur correction device for the purpose of preventing or reducing image blur, but in the case of the conventional optical correction method, the color shift remains unchanged in still image recording. There is a problem that the image is recorded and the quality of the captured image is reduced.
[0041]
The present invention has been made under such a situation, and it is an object of the present invention to provide an imaging apparatus capable of obtaining an image without blurring with little color shift in a still image shooting mode.
[0042]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, the imaging device is configured as in the following (1) and (2).
[0043]
(1) Vibration detection means for detecting the vibration of the imaging device, image correction means for optically correcting the blur of the image of the imaging optical system based on the output of the vibration detection means, and correction by the image correction means An imaging unit for capturing an image; a shooting mode switching unit for switching a shooting mode of the imaging unit between a moving image mode and a still image mode; and the image correction when the shooting mode is switched to the still image mode by the shooting mode switching unit. An image pickup apparatus comprising: a control unit that does not permit still image capturing when the correction amount of the unit is equal to or more than a predetermined value.
[0044]
(2) The imaging device according to (1), wherein the image correction unit includes a variable apex angle prism.
[0045]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention relates to a recording apparatus in which a video camera and a recording apparatus are integrally formed, and a recording apparatus in which the video camera and the recording apparatus are separated from each other, and the video camera and the recording apparatus are connected by wire or wirelessly. It can be implemented in a separate form. Further, the present invention can also be implemented by using a display device and a recording device of a device such as a personal computer that inputs a line from the imaging device without providing a monitor and a recording device in the imaging device itself.
[0046]
Hereinafter, the present invention will be described in more detail with reference to an embodiment in which a variable apex prism is used as an image correcting unit in the form of a recording device-integrated imaging device. The image correction means is not limited to the variable apex angle prism, but can be implemented using an appropriate optical correction means such as a lens tilt / shift type.
[0047]
【Example】
(Example 1)
FIG. 1 is a block diagram illustrating a configuration of a main part of an “imaging device” according to the first embodiment.
[0048]
In the figure, the same components as those of the conventional example shown in FIG. 5 are denoted by the same reference numerals, and detailed description is omitted.
[0049]
In FIG. 1, an angular velocity detecting means 1 comprising an angular velocity sensor such as a vibrating gyroscope attached to an imaging device, a DC cut filter (or HPF) 2 for cutting off a DC component of a velocity signal outputted from the angular velocity detecting means 1, and an angular velocity signal The amplifier 3, the driving circuit 9, and the image correcting means 10 for amplifying the signal to a predetermined level can have the same configuration as that of the conventional example.
[0050]
Further, reference numeral 13 denotes a recording device (not shown in FIG. 5) showing the conventional example, which can record a still image in addition to the conventional moving image. Reference numeral 11 denotes a recording control switch, which is a switch for the photographer to switch the photographing state to a moving image or a still image according to his or her own intention. Reference numeral 12 denotes a still image recording switch for photographing a still image when the recording control switch 11 is set to the still image recording state. A still image recording control circuit 14 outputs a still image recording permission signal to the recording device 13 only when the integrated value (= optical axis correction angular displacement) is within a predetermined range when the still image recording switch 12 is pressed. .
[0051]
In this embodiment, when the recording control switch 11 is set to the moving image recording side, the blur correction operation is controlled without any difference from the above-described conventional example.
[0052]
When the recording control switch 11 switches from moving image recording to still image recording, the recording device 13 switches the recording state from moving image to still image, and at the same time, the image sensor (not shown) also switches the imaging state to a state corresponding to the still image. It is also transmitted to the still image recording control circuit 14. When the mode is switched to the still image shooting state, the recording device 13 starts recording a still image in response to a recording signal input from the still image recording switch 12 via the still image recording control circuit 14.
[0053]
The operation of the COM at this time will be described with reference to the flowchart of FIG.
[0054]
# 21 This is the start of this flow, which is repeatedly started at a predetermined timing.
[0055]
# 22 It is determined that the recording control switch 11 is in the still image recording state.
[0056]
If the still image recording state has been selected, the processing in # 23 ends, and if the moving image recording state has been selected, the processing in # 26 ends.
[0057]
# 23 It is determined whether the still image recording switch 12 has been pressed.
[0058]
If the still image recording switch 12 is depressed, it is assumed that the photographer has requested the recording of a still image, and the process of # 26 is terminated if the still image recording switch 12 is not depressed.
[0059]
# 24 It is determined whether the integral value (= angular displacement) is within a predetermined range. If it is within the predetermined range, the process goes to # 25, and if it is outside the predetermined range, the process at # 26 ends.
[0060]
# 25 Start recording a still image.
[0061]
# 26 End of processing.
[0062]
The above processing is performed, and a still image can be recorded only when the integral value (correction angular displacement of the optical axis correction unit) is within a predetermined value in the still image recording state.
[0063]
FIG. 3 shows the angular displacement of the optical axis during panning or tilting when recording a moving image and when recording a still image.
[0064]
This figure shows, as a graph, the angular displacement of each part when the imaging apparatus of the embodiment is swung in a single direction, and in this description, the pan / tilt determination circuit makes a determination based on an increase in the angular displacement (= integral value). A description will be given of the state at the time (when Yes is determined in # 07 of FIG. 5).
[0065]
FIG. 3 shows the angular displacement of the photographing device, the angular displacement of the optical axis, and the situation of still image photographing during panning or tilting.
[0066]
FIG. 3 is a graph showing the angular displacement of each part when the imaging apparatus is swung in a single direction.
[0067]
FIG. 71 shows the angular displacement (shake) of the image pickup device or the like, and 72 shows the angular displacement of the optical axis correction amount at that time.
[0068]
Reference numeral 73 denotes a threshold value of an angular displacement (a threshold value of an integral value) at the time of capturing a moving image. When the threshold value is exceeded, panning or tilting is determined by the pan / tilt determination circuit. To shift the cutoff frequency to the high frequency side, change the characteristic so that the shake correction system does not respond to the low frequency, and further center the correction position of the image correction means gradually to the center of the movement range. Then, the time constant of the integration characteristic of the integrator 6 is shifted in the direction of shortening, and control is performed using the value accumulated in the integrator as a reference value.
[0069]
Reference numeral 74 denotes a threshold value for determining the start of recording by the still image recording control circuit 14. When the optical axis correction amount 72 is below the threshold value 74 (on the side where the correction amount is smaller), the threshold value 74 is set. As shown in the flowchart, still image recording is permitted. Conversely, if the image is above the dotted line (the side with the larger correction amount), the still image recording is not performed.
[0070]
Reference numerals 75, 76, and 77 indicate the ranges in which the still image recording is permitted in the same graph. As described above, 75 and 77 indicate the ranges in which the still image recording is permitted. Indicates that works effectively. Reference numeral 76 indicates that the still image recording switch 12 is invalid (recording is not started).
[0071]
As can be seen from the figure, the still image recording switch 12 is effective only in the area where the optical axis correction amount is small (= the color shift is small), and conversely, in the area where the optical correction amount is large (= the color shift is large). The recording switch 12 becomes invalid.
[0072]
In this embodiment, when the still image recording switch 12 is continuously pressed from a state where the optical correction amount is large (for example, the region 76 in FIG. 3), a region where the correction amount is small (for example, the region 77 in FIG. 3). The recording of the still image is started at the time when the recording time is changed to.
[0073]
As described above, according to the present embodiment, when the mode is switched to the still image shooting mode, an image with little color shift and no blur can be recorded.
[0074]
(Example 2)
The second embodiment has the same hardware configuration as the first embodiment, but differs from the first embodiment in the processing after the still image capturing switch 12 is turned on.
[0075]
FIG. 4 is a flowchart for explaining the operation of the “photographing device” according to the second embodiment.
[0076]
The operation of the COM in this embodiment will be described with reference to the flowchart.
[0077]
# 41 This is the beginning of this flow, which is started repeatedly at a predetermined timing.
[0078]
# 42 It is determined that the recording control switch 11 is in the still image recording state.
[0079]
If the still image recording state has been selected, the processing in # 43 ends, and if the moving image recording state has been selected, the processing in # 46 ends.
[0080]
# 43 It is determined whether the still image recording switch 12 has been pressed.
[0081]
If the still image recording switch 12 is depressed, it is assumed that the photographer has requested the recording of a still image, and the process in # 44 is terminated if the still image recording switch 12 is not depressed.
[0082]
# 44 It is determined whether the integral value (= angular displacement) is within a predetermined range. If it is within the predetermined range, the process proceeds to # 45, and if it is outside the predetermined range, the same determination (# 44) is performed again.
[0083]
# 25 Start recording a still image.
[0084]
# 26 End of processing.
[0085]
As described above, the difference from the first embodiment is that the processing is terminated (# 26) when the integral value (angular displacement) exceeds a predetermined value in the first embodiment, In the example, the determination is repeated at # 44 until the integrated value falls within a predetermined value.
[0086]
Thus, when the still image capturing switch 12 is pressed even once in the still image capturing state, the determination is repeated until the integrated value falls within the predetermined value, and then the still image recording is started.
[0087]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a good image with little color shift and no blurring in the still image shooting mode.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a main part of a first embodiment. FIG. 2 is a flowchart showing an operation of the first embodiment. FIG. 3 is a diagram showing still image recording control in the first embodiment. FIG. 5 is a diagram showing a configuration of a main part of a conventional example. FIG. 6 is a flowchart of panning / tilting determination. FIG. 7 is a diagram showing a configuration and operation of a variable apex angle prism. FIG. 9 is a diagram showing a blur correction operation by a vertical angle prism. FIG. 9 is a block diagram showing a configuration for controlling a variable vertical angle prism.
DESCRIPTION OF SYMBOLS 1 Gyro 7 Pan / tilt determination circuit 10 Image correction means 11 Recording control switch 12 Still image recording switch

Claims (2)

Vibration detecting means for detecting vibration of the imaging device, image correcting means for optically correcting a blur of an image of an imaging optical system based on an output of the vibration detecting means, and imaging of the image corrected by the image correcting means A photographing mode, a photographing mode switching means for switching a photographing mode by the photographing means between a moving image mode and a still image mode, and a correction by the image correcting means when the photographing mode is switched to the still image mode by the photographing mode switching means. An image pickup apparatus comprising: a control unit that does not permit still image shooting when the amount is equal to or more than a predetermined value. 2. The image pickup apparatus according to claim 1, wherein the image correction means includes a variable apex angle prism.

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