JP2801013B2 - Camera image stabilizer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image blur prevention device for a camera that detects the amount of camera shake and changes the optical path of a photographing optical system to correct image shake due to camera shake. It is.

[Conventional technology]

Conventionally, in this type of image blur prevention apparatus, in order to accurately obtain an image blur prevention effect, it is necessary to accurately detect the amount of camera shake and to determine the optical path of the correction optical system according to the amount of shake detected. It needs to be corrected accurately.

In order to accurately detect the shake amount, it is required to shorten the time required for the detection, in addition to the performance of the shake detection device itself for detecting the shake amount such as a hand shake.

[Problems to be solved by the invention]

By the way, the shake detection device provided in such a conventional image blur prevention device requires a predetermined time or more at the beginning of detection start. In other words, if an attempt is made to apply position feedback to the correction optical system using an acceleration sensor to detect a shake amount such as a camera shake amount, an integration operation is performed twice, and the frequency required by the integration operation itself is increased. It was getting longer accordingly.

Therefore, in a camera including a video camera equipped with such an image blur prevention device, if a photographer presses a release button or a recording start button and there is a certain time lag, a valuable shutter chance is obtained. Or give the photographer an unpleasant image. From this, in an image blur prevention device attached to a camera or the like, in a steady state, in order to use a shake detection device showing excellent detection capability in a short time from pressing a release button or the like to opening a shutter, The detection characteristics on the low frequency side had to be sacrificed.

There is also an image blur prevention system that uses a position sensor such as a hydro sensor for position detection and applies position feedback to a correction optical system. In this case, the acceleration
Unlike the method using a speed sensor or the like, instead of performing the integration operation, it is necessary to perform processing such as initial position determination of a position sensor and centering of a correction optical system for a camera that constantly moves largely. These processes basically cause deterioration of the camera shake detection ability on the low frequency side of the position sensor.

On the other hand, when a general photographer or the like takes a photograph in a museum, for example, the camera may be fixed to a tripod or the like, and the camera itself may be photographed without much movement and without having to worry about the release time lag. In photography in the museum, strobe photography is generally prohibited, so the shutter open time is lengthened, and camera shake on the low frequency side due to pressing the release button also affects the photograph. . Therefore, in photographing in such a situation, a need has arisen for a shake detection device to accurately detect a shake amount such as a camera shake of a camera up to a low frequency side.

In view of the above drawbacks, when the camera is supported by a camera supporting means such as a tripod, the present invention can detect the camera shake by expanding the detection capability of the shake detection device to the low frequency side and reliably prevent image blur. It is an object of the present invention to provide an image blur prevention device for a camera that can be used.

[Means for solving the problem]

The gist for achieving the object of the present invention is:
A camera shake detecting means for detecting a shake amount of a camera capable of changing a detection frequency region, an optical path changing means capable of changing an optical path of an imaging optical system of the camera, and the camera supported by a camera fixing member. Camera support detecting means for detecting that the image path has been shaken, and control means for driving and controlling the optical path changing means in a direction in which image shake does not occur according to the camera shake amount from the camera shake detecting means. Means are
When the camera support detection unit detects that the camera is supported by the camera fixing member, the detection frequency region of the camera shake detection unit is controlled so that the low frequency region can also be detected. It is in the image blur prevention device.

[Action]

The camera shake preventing apparatus configured as described above can detect camera shake in a low frequency region when the camera is supported by a camera fixing member such as a tripod.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1A is a schematic block diagram showing an embodiment of an image blur prevention device for a camera according to the present invention.

1 is a sequence control circuit composed of a microcomputer for controlling the sequence of the entire camera and an image blur prevention system at the time of shooting, and 2 is a camera such as a camera shake camera by a speed sensor such as an acceleration sensor or a vibration gyro, or a position sensor such as a hydrostatic. A camera shake detecting device 3 for detecting a shake receives an output signal from the camera shake detecting device 2 and corrects an optical axis entering a photographing optical system by a variable apex prism or moves a photographing lens itself to change a photographing optical path. Optical path correcting means 4 for correction, a camera support fixing member such as a tripod for supporting and fixing the camera, and a camera fixing detection switch 5 for detecting that the camera is fixed to the camera support fixing member 4.

The sequence control circuit 1 detects whether or not the camera supporting and fixing member 4 such as a tripod is fixed to the camera by a switch signal from a camera fixing detection switch 5, and based on the detection signal, determines a frequency characteristic of the camera shake detecting device 2. If the sensor of the camera shake detection device 2 is a speed sensor, the time constant of the integration circuit is set. If the sensor is a position sensor, the control for initial position determination is gently performed and the control of the camera shake detection device 2 is performed. Change the frequency characteristics. Then, the sequence control circuit 1 drives the optical path correcting means in accordance with the shake information from the camera shake detecting device 2, and corrects the photographing optical path to obtain a sharp image without image shake.

FIG. 1B is a schematic diagram showing an embodiment of a specific configuration of the image blur prevention device for a camera described above.

In this example, the optical path correction means 3 includes a variable apex angle prism (hereinafter abbreviated as VAP) 6 disposed on the front surface of the taking lens system,
The VAP 6 comprises a VAP drive circuit 7 for driving the VAP 6 and a front lens 8 of a photographic lens system. The VAP 6 seals liquid between a transparent fixed plate 6a and a transparent movable plate 6b, and a voice coil 6c
By driving the movable plate 6b, the angle between the fixed plate 6a and the movable plate 6b is changed to change the optical axis.

Also, a tripod is used as the camera supporting and fixing member 4. When the camera fixing screw of the camera platform is attached to the camera 9, the camera fixing detecting switch 5 is pressed and turned on, and the signal is transmitted to the sequence control circuit 1. Is done.

FIG. 2 shows the actual amount of camera shake on the film surface.
The vertical axis represents the amount of camera shake, and the horizontal axis represents time. Here, FIG. 2 (A) shows the time change of the camera shake amount on the film surface when the photographer holds the camera, and in addition to the high frequency vibration, the gentle low frequency vibration is applied. I understand. Here, the shutter opening time t ₁ by pressing the release button performs the normal photographing, since a relatively short time, amount of blur on the film surface ([Delta] x ₁₎ is seen that the high-frequency vibration is dominant. FIG. 2 (B) shows a case where the camera is fixed to a tripod and long-time exposure shooting is performed. Since the camera is fixed, the whole amount of blur is small.
Here, if the tripod itself is vibrating slowly,
Only the shutter opening time t ₂ is longer minute, shake amount on the film surface ([Delta] x ₂₎ is increased. Therefore, in normal shooting, the camera shake amount on the low frequency side may be sacrificed to a certain extent, but when shooting on a tripod etc. for long exposure, the camera shake amount of low frequency must be taken into account. No.

FIG. 3 shows an actual camera shake detection device. Here, a shake detection device when a vibration gyro is used as a shake sensor is shown. 51 is a piezoelectric element 54-a, 54-
b, 54-c, 54-d is a bar-type vibrator fixed,
Vibration is driven by the piezoelectric element 54-a, and angular velocity is detected by 54-c and 54-d. Further, the vibrator 51 includes support members 52, 53
Are held by a support case (not shown) or the like. The support members 52 and 53 are desirably provided at the nodes of the vibrator 51. These vibrator 51, support members 52 and 53 and piezoelectric element 5
4 and the like constitute a camera shake sensor A. 55
Is a bar type vibrator drive circuit, which drives the vibrator 51 by the piezoelectric element 54a. 57 is a resonance point detection circuit,
This circuit detects and holds the resonance frequency 51 (the minimum frequency at which the vibrator has the maximum amplitude at the same drive voltage).
Reference numeral 58 denotes a bar-type vibrator displacement detection circuit for detecting, from the piezoelectric element 54-b, how much the vibrator 51 vibrates by the bar-type vibrator drive circuit 55, and a resonance point detection circuit 57 based on this signal. Then, the resonance point is obtained, and then the constant amplitude control circuit 56 makes the amplitude constant to normalize the angular velocity signal. 59 is a vibration stabilizing drive circuit, after finding the resonance point of the vibrator 51, the constant amplitude control circuit 56 tries to make the amplitude of the vibrator 51 constant, but at that time the amplitude of the vibrator 51 is stabilized It is a circuit that detects whether or not it is, controls the analog switch 64, and starts transmitting the camera shake angular velocity signal only after it is in the appropriate amplitude state,
The start of camera shake signal detection is transmitted to the sequence control circuit 1. These circuits 55 to 59 constitute a camera shake sensor control drive circuit B. Reference numeral 60 denotes a demodulator and a filter circuit for detecting only the angular velocity component due to camera shake from the signals of the piezoelectric elements 54-c and 54-d perpendicular to the driving piezoelectric element 54-a to the vibrator 51. The angular velocity signal is subjected to temperature compensation and offset compensation by the compensation circuit 61. These circuits 60 and 61 constitute a camera shake amount detection circuit C. After the camera shake angular velocity is driven at a constant amplitude at the resonance point by the vibration stabilization detection circuit 59, the analog switch
64 is turned on and a signal is transmitted. This signal is output to the integration circuit 62
, The camera shake speed becomes the camera shake displacement. Here, the integration circuit 62 can switch the time constant by the signal of the sequence control circuit. The camera shake displacement signal is a camera shake displacement amount indicating how many μm the camera is actually displaced by the normalization circuit 63. And these circuits 62,6
3 constitutes a camera shake amount-absolute displacement conversion circuit D. 65 is a power supply for the camera shake detection system, 66 is a control circuit for controlling whether to supply power to the camera shake detection system from the power supply 65, 67
Is an initial setting circuit for initial setting of a camera shake detection system by a signal from the power-on control circuit 66.

Next, the operation of the camera shake detection system configured as described above will be described with reference to the flowchart of FIG.

When the first switch SW1 for performing photometry, distance measurement, and the like is turned on by the photographer pressing the release button of the camera halfway, the sequence control circuit 1 transmits a start signal to the camera shake detection system (# 101). . Then, the power-on control circuit 66 supplies power to the camera shake detection system from the power supply 65 (# 102), and outputs an initial setting signal from the initial setting circuit 67 (# 103). Based on this signal, all the circuits of the camera shake detection system are reset. After the reset is released, the bar-type vibrator drive circuit 55 sets a voltage according to the initial set value (# 104), sets the vibrator drive frequency to the initial set value (# 105), and sets the voltage element 54-a. Is driven, the vibrator 51 starts to vibrate. The piezoelectric element 5 which forms a 180 ° pair with the driving piezoelectric element 54-a by driving the vibrator 51
4-b outputs the vibration state of the vibrator 51 (# 106). From this signal, the displacement amount of the transducer 51 is detected by the transducer displacement signal detection circuit 58 (# 107). Then, the detection circuit 57 detects whether or not the frequency is a resonance point (# 108). If the frequency is a resonance point, the vibration frequency is stored and fixed. If not, the vibrator driving frequency is changed again. (# 109)
The same operation is repeated until a resonance point is found. next,
When the resonance frequency is detected, the displacement of the vibrator 51 is detected again (# 110), and it is determined whether or not the displacement is the predetermined displacement (# 111).
If they are different, the drive voltage of the piezoelectric element 54-a is changed (# 112) and repeated until a predetermined displacement amount is obtained. Then, after a certain period of time (# 113) for the vibration stabilization wait and the drift stabilization wait of the oscillator 51, the analog switch 64 is turned on by the sequence control circuit 1 and the vibration stabilization determination circuit 59.

Next, an operation when a camera shake actually occurs will be described. Here, since the principle of angular velocity detection by the vibrating gyroscope is known, detailed description is omitted. However, when a force acts on the vibrator 51 that is stably vibrating in a direction perpendicular to the vibration direction, the force and the vibration direction are determined by the Coriolis force. Since a force is generated in the vertical direction, the force is detected by the piezoelectric elements 54-c and 54-d (#
114). From this signal, only a pure angular velocity component is detected by the demodulator circuit filter circuit 60 (# 115, # 11
6) After the offset, temperature drift and the like of the amplifier are removed by the compensating circuit 61 (# 117), integration is performed to obtain an angular component (displacement component). At this time, the detection band of the camera shake detection system that is currently being performed is set by a signal from the sequence control circuit 1 (# 118), and thereby the integration constant is set (# 119, # 120). For example, when the shutter speed is high (that is, when the shutter speed is high), the integration constant is reduced (# 119, # 120) so that the camera can immediately respond to the release, and a camera is mounted on a tripod or the like, and long-time exposure shooting is performed. Is performed, that is, when the camera fixed detection switch 5 is on, the integration constant is increased (# 12).
0), slow camera shake due to camera shake can be detected. Thus, the angular velocity signal is converted into an angle signal (# 12
1), normalize (# 122), transmit high-speed A / D-converted data to the sequence control circuit 1 as the amount of camera shake displacement (# 1)
twenty three). Thereafter, the sequence control circuit 1 determines whether or not a camera shake detection stop signal has been received (# 124). If not, the process returns to # 110 and the same operation is performed again. When the sequence control circuit 1 sends a camera shake detection stop signal due to the first switch SW1 being turned off or the end of photographing or the like, it is determined (# 124), and the driving of the vibrator is stopped (# 125). The power supply from the power supply 65 is cut off (# 126), and the camera shake detection operation ends.

FIGS. 5A, 5B, and 5C show specific configurations of the integration circuit 62 shown in FIG. 3, respectively. Reference numeral 70 denotes an operational amplifier for integrating the shake speed signal. 71, 73, 75 are input resistors, 72, 74, 76 are analog switches for connecting and disconnecting the resistors 71.73, 75 and the shake speed signal, 81, 83, 85 are capacitors, 82, 84, 86 is an analog switch for connecting and disconnecting the capacitors 81, 83, 85 and the output of the operational amplifier 70.
It is. FIG. 5 (A) shows that the integration capacitors 81, 83, 85 are controlled by the control signal from the sequence control circuit 1 in analog SW.
Turn on, turn off 82, 84, 86 to change the integration time constant. FIG. 5B shows that the resistors 71, 73, 75 are turned on by the control signals from the sequence control circuit 1 to turn on the analog SWs 72, 74, 76.
Turn off to change the integration time constant.

FIG. 5 (C) shows a combination of the integrating circuit of FIG. 5 (A) and the integrating circuit of FIG. 5 (B).

FIG. 6 is a schematic diagram showing a hydrostatic sensor according to another embodiment of the present invention. This is an example in which the characteristics on the low frequency side when a tripod is mounted are improved by changing the frequency characteristics of the hydrostatic sensor.

101 is a light projecting element such as iRED that projects light toward a mirror 108 attached to a floating body 107, 102 is a holding member of the light projecting element 101, and 103 is a projected image from the light projecting element 101 reflected by the mirror 108. A position detection sensor 104 such as a PSD for detecting the camera shake amount from the position, and 104 is a holding member for the position detection sensor 103. Reference numeral 105 denotes a frame in which a liquid 106 is sealed and a floating body 107 is provided so as to be able to float inside. For example, a facing portion between the light emitting element 101 and the position detection sensor 103 is formed transparent. Even if the camera rotates together with the frame 105, the floating body 107 is fixed by a member having a small frictional force so that the absolute position of the floating body 107 itself does not change. Reference numeral 108 denotes a mirror which is provided in a floating body and partially reflects a light projected image from the light emitting element 101 by a slit or the like and reflects the light to the light receiving element 103. 109
Is a yoke, 110 is a coil, 111 is a yoke, these yokes
An electromagnetic loop is configured by 109, 111, and the coil 110 to set an initial position of the floating body 107, which will be described later, and to change a spring term which is one of the factors of the transfer characteristic of the hydrostatic sensor.

Now, the operation of the hydrostatic sensor configured as described above will be described.

First, when the camera is not operating, the position of the floating body 107 is uncertain due to its own imbalance, low frequency operation of the camera itself, and the like. For this purpose, a current is applied to the coil 110 by a half-press operation of a camera release (not shown), and an electromagnetic loop is formed by the coil 110, the yoke 109, the floating body 107, and the yoke 111, and the floating body 107 is set to an initial position. Thereafter, the current flowing through the coil 110 is weakened so that the floating body 107 itself can freely rotate, and the absolute position can be maintained even if the camera body vibrates or rotates due to hand shake or the like. Here, the transfer characteristics of this hydrostatic sensor are roughly It is expressed as The inertia term is determined by the size and weight of the floating body 107, and the viscosity term is determined by the viscosity coefficient between the floating body 107 and the liquid 106. Since the spring term is substantially proportional to the electromagnetic force, and the electromagnetic force is proportional to the coil current, the characteristics of the hydrostatic sensor can be changed by variously changing the current value.

The projected image from the light projecting element 101 is reflected only at the slit portion by the mirror 108 in the floating body 107, but when the camera is moved by hand shaking, the light projecting element 101 and the floating body 107 and the floating body 107 and the light receiving element The relative position of 103 changes, and therefore, the light receiving element 103 changes the amount of camera shake (the shake rotation angle in this case) by the change in the center of gravity of the reflected light from the mirror 108.
Can be detected.

Now, when a tripod is attached, FIG. 1 (B)
When the switch 5 is turned on, the current value is made smaller than the normal set value to improve the frequency characteristics on the low frequency side.

In the above-described embodiment, when the camera is supported and fixed by the tripod, the camera shake detection band of the camera shake detection device 2 can detect the camera shake in the low frequency region by the signal from the camera fixed detection switch 5. The invention is not limited to this. For example, FIGS. 7 (A) and (B)
As shown in FIG.
The camera 101 may be provided so that it can be pulled out from the bottom of the camera body 100, and when the leg 101 is pulled out, the camera fixing detection switch 5 is turned on. In this case, the use of the leg piece 4 is performed, for example, as shown in FIG.
Pull out and use when tilting the camera mounted on 2.

〔The invention's effect〕

As described above, according to the present invention, when performing long-time exposure by fixing the camera using a tripod or the like, by expanding the detection capability of the camera shake detection means on the low frequency side, it is possible to perform normal shooting. Also, it is possible to provide a sharp photograph without image blurring even if the exposure is performed for a long time without increasing the release time lag or the like.

[Brief description of the drawings]

FIG. 1A is a schematic block diagram showing an embodiment of a camera image blur preventing device according to the present invention, and FIG. 1B is a schematic diagram showing an example of a specific configuration thereof. FIG. 2 (A) is a diagram showing a time change of a camera shake amount when the camera is held, FIG. 2 (B) is a diagram showing a time change of the camera shake amount when the camera is fixed to a tripod, and FIG. Is a block diagram of a camera shake detecting device using a speed sensor, FIG. 4 is a flowchart showing the operation of the camera shake detecting device of FIG. 3, and FIGS. 5 (A), (B) and (C) are FIG. Circuit diagram of the integration circuit of
FIG. 6 is a view showing a hydro sensor, and FIG.
(B) is a front view and a side view showing another embodiment. DESCRIPTION OF SYMBOLS 1 ... Sequence control circuit 2 ... Camera shake detection device 3 ... Optical path changing means 4 ... Camera support fixing member 5 ... Camera fixing detection device 6 ... Variable angle prism (VAP) 7 ... VAP drive circuit

Claims (1)

(57) [Claims] 1. A camera shake detecting means for detecting a shake amount of a camera capable of changing a detection frequency region, an optical path changing means capable of changing an optical path of a photographing optical system of the camera,
Camera support detection means for detecting that the camera is supported by the camera fixing member, and drive control of the optical path changing means in a direction in which image shake does not occur according to the camera shake amount from the camera shake detection means Control means, the control means, when the camera support detection means detects that the camera is supported by the camera fixing member, the detection frequency region of the camera shake detection means also the low frequency region side An image blur prevention device for a camera, which is controlled to be detectable.