JPH03122629A - Vibration isolator - Google Patents

Abstract

PURPOSE:To obtain a highly accurate vibration proofing action when a correcting optical system moves in the vicinity of a central part and a stable vibration proofing action when the system moves in the vicinity of a driving limit by providing a servo gain varying means varying a servo gain according to the driving position of the correcting optical system. CONSTITUTION:A variable gain amplifier 8 is so designed to obtain a high gain when a lens is positioned close to the central part and to obtain a low gain on other occasions. When blurring occurs and the lens 2 is within a range 2 close to the central part, the gain of the variable gain amplifier 8 doubles; that means a high servo gain. Therefore, the lens 2 is driven at high accuracy with respect to an angular velocity signal from an integrator 9. If the lens 2 exceeds the range 2, the lens 2 is driven so that the gain of the variable gain amplifier 8 becomes automatically unmagnified and the amplifier 8 stably operates. In such a way, a highly accurate vibration proofing action is obtained when the correcting optical system moves in the vicinity of the central part and a stable vibration proofing action which develops no hunching is obtained when the system moves in the driving limit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a vibration isolating device that prevents image blur caused by camera shake.

(Background of the Invention) Among conventional vibration isolators of this type, the 7th one is representative.
The two types shown in FIG. 8 and FIG. 8 will be discussed below.

First, the systems shown in FIGS. 7 and 8 will be briefly explained.

The image stabilization device shown in FIG. 7 is attached to a camera lens barrel, and uses a vibration detection device 42 to detect a camera shake signal in the direction of the arrow (hereinafter referred to as the direction of rotation of the page), and in response to this signal, the correction lens 36 This is a configuration that prevents the image from blurring due to camera shake on the apparent imaging plane.

An example of a conventional vibration isolating device of this type is disclosed in Japanese Patent Application Laid-Open No. 62-47012.

FIG. 8 shows another conventional device, which is constructed on a frame 50 so that the lens 44 and the image plane (that is, the image sensor 48) can rotate at a point 0 on the optical axis, and the angular velocity is detected. The device 47 is also fixed on the frame 50 so that the axis of rotation and the axis of sensitivity are parallel. And angular velocity sensor 47
The output is sent to an actuator that drives the frame in the rotating direction, forming a feedback loop. As a result, even if the entire lens 44 shakes due to camera shake, the actuator moves so that the resulting output signal of the angular velocity sensor 47 becomes smaller, and the frame 50 responds accordingly.
rotates, so even if the lens barrel (not shown) shakes due to camera shake, the lens 44. The image sensor 48 is configured to always remain substantially stationary in the rotational direction and to obtain images without image blur.

As a publicly known example of this method, for example, Japanese Patent Publication No. 60-143
Examples include No. 330.

In the conventional apparatus shown in the above two figures 7 and 8, only the system for preventing image blur in the direction of rotation of the page is shown to simplify the drawings; Needless to say, it is equipped with a surface vibration isolation system.

Here, an explanation is added for each operation.

First, in FIG. 7, 35 is a spring, one end of which is fixed to the lens barrel, the other end of which is connected to the lens 36.
It has the function of holding 6 in the center. 37 is a film on the image plane. As mentioned above, 42 is a vibration detection device that outputs an angle signal in the direction of rotation of the entire lens in the paper plane due to camera shake. 38 is a coil, and 39 is a magnet fixed to the lens 36. A potentiometer 40 moves in conjunction with the magnet 39 and outputs a position signal for the lens 36. Reference numeral 41 denotes a differential amplifier, and the differential amplifier 41, potentiometer 40, coil 38, magnet 39, and spring 35 constitute a position control type actuator for driving the position of the lens 36 in the vertical direction in the drawing.

The angle signal detected by the vibration detection device 42 is input to the differential amplifier 41, and the lens 36 is driven so as to apparently stop the vibration on the surface of the film 37 due to camera shake, and the lens 36 as a whole constitutes a vibration isolator. There is.

Next, the vibration isolating device shown in FIG. 8 will be explained.

In FIG. 8, both the lens 44 and the imaging device 48 are fixed to a frame 50 and can move in the direction of rotation of the plane of the paper about a point O. Reference numeral 43 denotes a spring, one end of which is fixed to a lens barrel (not shown) and the other end of which is fixed to the frame 50, and has the function of holding the frame 50 at the center.

As mentioned above, 47 is an angular velocity sensor, which is attached to the frame 50 so that its sensitivity axis coincides with the rotation axis of the frame 50.
is fixed. 46 is the amplifier, 45 is the frame 50
A magnet is attached to the frame 50, and 49 is a coil, which together with the spring 43 constitute an actuator that drives the frame 50, the lens 44, the image sensor 48, and the angular velocity sensor 47 attached thereto in the direction of rotation in the plane of the paper around point O. ing.

When the angular velocity is detected by the angular velocity sensor 47, the actuator moves the sensor 4 in the opposite direction.
A force that rotates the entire frame 50 including 7 itself is applied. Due to this servo mechanism, the entire frame 50 remains stationary in the direction of rotation around point O within the lens barrel even if the lens barrel surrounding it moves.

In the conventional device shown in FIGS. 7 and 8 described above, a servo circuit is used to drive the lens, and an actuator is used to move the image on the imaging plane in the opposite direction to correct the movement of the image due to camera shake. This is to stop the upward movement blur, but in order to drive the lens more accurately, the servo gain needs to be high enough.

However, since the actuator's movable range is relatively narrow, it often runs out of its stroke during shooting and hits the end of its drive range, and when it hits in this way, the higher the servo gain, the greater the shock. At the same time, there were other problems such as excessive current flowing through the actuator (to return it to the center position).

In order to avoid this problem, the applicant of the present application
No. 1290, etc., proposes limiting the drive range of an actuator by limiting the human power signal of a servo circuit according to the drive position of the actuator. However, controlling the input signal to stop the lens movement near the limit of the actuator's drive range is equivalent to applying 5 TEP human power (pulse human power) to the servo circuit, and the servo gain is high and sufficiently stable. In the case of a servo system that does not have a servo system, there are problems such as a hunting state at this time, which sometimes conflicts with the requirement to have a high servo gain in order to perform highly accurate vibration isolation.

(Objective of the Invention) The object of the present invention is to solve the above-mentioned problems, and when the correction optical system moves near the center, performs a highly accurate vibration-proofing operation.
Hunting does not occur when moving near the drive limit.
It is an object of the present invention to provide a vibration isolating device capable of performing stable vibration isolating operation.

(Characteristics of the Invention) In order to achieve the above object, the present invention includes, in the vibration isolating means,
A servo gain variable means is provided to change the servo gain according to the drive position of the correction optical system, so that when the correction optical system moves near the center, the servo gain is automatically increased, and the correction optical system The servo gain is automatically lowered when the motor moves near the limit of the driving range.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, where 1 is a spring;
One end is fixed to the lens barrel, the other end is connected to the lens 2, and has the function of holding the lens 2 in the center. 3
is a magnet attached to the lens 2, 4 is a coil, 13 is a film on the imaging plane, 5 is a potentiometer that outputs a position signal of the lens 2 whose position changes, 6 is a differentiator, 7
is a differential amplifier, and 8 is a variable gain amplifier. The above spring 1, coil 4, magnet 3, potentiometer 5, differentiator 6
, a differential amplifier 7, and a variable gain amplifier 8 constitute a speed control actuator 14. Reference numeral 10 denotes an angular acceleration detection device, that is, an angular accelerometer, which is arranged so that the direction of rotation of the paper surface coincides with the sensitivity axis.

The angular acceleration signal detected by the angular accelerometer 10 is integrated by an integrator 9, converted into an angular velocity signal, and is inputted to an actuator 14 for speed control through a stroke limiter 15. Further, the stroke limiter 15 is
When a signal indicating that the position of the lens 2 exceeds the predetermined range 1 shown in FIG. After that, the range within which lens 2 can be driven by the central force of spring l! When the lens returns to the inside, the angular velocity signal is transmitted to the actuator 14 again to drive the lens for image stabilization.

The variable gain amplifier 8 is configured so that the gain is high when the lens 2 is located near the center shown in the range 2 in FIG. 2, and the gain is low otherwise. This situation is shown in FIG. Further, the relationship between range 2 and range 1 described above is configured such that range 1>range 2.

With the above configuration, when the lens barrel is held by hand and camera shake occurs, and the vibration isolator is activated, an angular acceleration signal caused by the camera shake is generated in the angular accelerometer 10 and sent to the integrator 9. is output. The actuator 14 for controlling the speed of the lens 2 is arranged so that the lens 2 is at a second position near the center.
If it is within range 2 in the figure, the gain of the variable gain amplifier 8 is double, which is a high servo gain, so the lens 2 is driven with high precision in response to the angular velocity signal from the integrator 9. . Thereby, a high vibration damping effect can be obtained.

Furthermore, when the lens 2 exceeds the range 2 shown in FIG. 2, the gain of the variable gain amplifier 8 is automatically increased to 1, and the actuator 14 drives the lens 2 to operate stably with a low servo gain. .

Furthermore, if the stroke limit in range 1 set in advance is exceeded, the angular velocity signal input to the actuator 14 is cut off by the stroke limiter 15, and the velocity of the lens 2 is controlled to be zero, so that the electrical Drive restrictions are applied. At this time, the gain of the variable gain amplifier 8 in the actuator 14 is low, and the gain of the variable gain amplifier 8 in the actuator 14 is low.
4 allows a stroke limit to be applied in a stable state.

4 and 5 are diagrams showing specific configuration examples of the variable gain amplifier 8 and the stroke limiter 15, respectively.

In Figure 4, 62.63, 70.71 are resistances, 61.65
．． 68 is a diode, 64.67.72 is an operational amplifier,
66 is a volume. Reference numeral 69 denotes an analog switch, which enters the illustrated state, that is, the on state, when a high-level signal is input.

In FIG. 5, 77.78 is a resistor, 80, 81.84 are diodes, 82 is a volume, and 79.83 is an operational amplifier. Reference numeral 85 denotes an analog switch, which enters the illustrated state, that is, the on state, when a high-level signal is input.

FIG. 6 shows another embodiment of the present invention, in which 20 is a spring, one end of which is fixed to the lens barrel, and the other end of which is attached to the frame 21, which holds the entire frame at approximately the center position. It has the function of The frame 21 is rotatable around a point O, and includes a lens 23 and an image sensor 2.
2 is fixed to the frame 21. 28 is an angular velocity sensor, which is attached to the frame 21 so that its sensitivity axis is the same as the rotation axis of the frame 21. 24 is a coil fixed to a lens barrel (not shown), 25 is a magnet,
It is attached to the frame 21. 27 is a variable gain amplifier similar to the first embodiment, and 26 is a potentiometer, which works in conjunction with the magnet 25 to generate a position signal for the frame 21, that is, for the lens 23.

In the above configuration, when a lens barrel (not shown) is held by hand and camera shake occurs, and the vibration isolator is activated, an angular velocity signal is generated in the angular velocity meter 28. This angular velocity signal is transmitted to the coil 24 through the variable gain amplifier 27, thereby generating a driving force in the direction in which the frame 21 and the sensor 28 themselves become stationary. As a result, the frame 21 remains stationary in absolute space and does not rotate, centering on point 0, regardless of camera shake, so that a stationary, blur-free image can be obtained.

Although the rotation range of the frame 21 has physical limitations as described above, the variable gain amplifier 27 operates at maximum gain when driven near the center of the circle, and operates at a low gain at the end of the stroke.

Thereby, since the servo gain is low when the frame 21 physically hits the end of the stroke, the shock can be alleviated.

According to this embodiment, a function that can change the servo gain is added to the servo circuit that drives the actuator of the anti-vibration device, and a high servo gain is applied when the lens is near the center during anti-vibration operation. This allows for highly accurate driving, and since a low servo gain is applied when there is a lens near the end of the stroke, it is possible to construct a stable vibration isolator that does not cause hunting etc. .

In addition, by using the previously proposed methods such as Japanese Patent Application No. 63-253247 and Japanese Patent Application No. 63-311290,
During actual photography, the actuator can be used at a position close to the center of the stroke of the actuator, that is, in a range where the servo gain is high, and highly accurate image stabilization photography can be performed.

(Correspondence between the invention and the embodiments) In this embodiment, the lens 2 or 23 is the correction optical system of the present invention, the angular accelerometer 10 or the angular velocity meter 28 is the vibration detection means, and the spring 1, the magnet 3, and the coil 4, potentiometer 5, differentiator 6, differential amplifier 7, variable gain amplifier 8
, or spring 20, frame 21. Coil 24, magnet 25
, the potentiometer 26 and the variable gain amplifier 27 serve as anti-vibration means, and the variable gain amplifier 8 or the variable gain amplifier 28
correspond to the servo gain variable means.

(Effects of the Invention) As explained above, according to the present invention, in the vibration isolating means,
A servo gain variable means is provided to change the servo gain according to the drive position of the correction optical system, so that when the correction optical system moves near the center, the servo gain is automatically increased, and the correction optical system When the motor moves near the limit of the drive range, the servo gain is automatically lowered.
When the correction optical system moves near the center, it is possible to perform highly accurate anti-vibration operation, and when it moves near the drive limit, it is possible to perform stable anti-vibration operation without hunting. .

[Brief explanation of drawings]

FIG. 1 is a configuration diagram including an electric block showing an embodiment of the present invention, and FIGS. 2 and 3 are diagrams for explaining the gain variable range of the variable gain amplifier shown in FIG. 1 and the gain state in each range. 4 is a circuit diagram showing an example of the configuration of the variable gain amplifier shown in FIG. 1, FIG. 5 is a circuit diagram showing an example of the configuration of the stroke limiter shown in FIG. 1, and FIG. 6 is another embodiment of the present invention. FIG. 7 is a block diagram including an electric block showing a conventional device, and FIG. 8 is a block diagram including an electric block showing another example of the conventional device. ■・・・Spring, 2...Lens, 3...
... Magnet, 4... Coil, 5... Potentiometer, 6... Differentiator, 7...
・Differential amplifier, 8...Variable gain amplifier, 10
... Angular accelerometer, 20 ... Spring, 21
...Frame, 23 ...Lens, 24
......Coil, 25...Magnet, 26...
... Potentiometer, 27 ... Variable gain amplifier, 28 ... Angular velocity meter.

Claims (1)

[Claims] (1) A correction optical system that is driven relative to the lens barrel to decenter the photographing optical axis, a vibration detection means that detects vibrations, and a servo control system that controls the correction optical system based on a signal from the vibration detection means. An anti-vibration device comprising a driving anti-vibration means, characterized in that the anti-vibration means is provided with a servo gain variable means for changing the servo gain according to the drive position of the correction optical system. Shaking device.