JP2001142103A - Image shake preventing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image shake preventing device constituted so that image shake is suitably prevented from occurring by detecting the speed of vibration applied to a camera using a vibration speed sensor, obtaining the derivative and the integrated value of the speed, setting the integrated value zero when the derivative becomes zero, properly setting the center of the action range of a vibration proof lens with respect to the vibration at an original position by controlling the position of the vibration proof lens based on the integrated value and eliminating an adverse effect caused by noise and the like included in a signal outputted by the vibration speed sensor. SOLUTION: A CPU 16 detects the angular velocity of the vibration from an angular velocity sensor 14 and the derivative and the integrated value of the angular velocity are obtained. Then, when the derivative becomes zero, the integrated value is corrected to be zero. Based on the integrated value, the vibration proof lens 10 is driven by a motor 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-shake device, and more particularly to an anti-shake device for driving an anti-shake lens of a television lens to prevent an image blur caused by vibration of a television camera.

[0002]

2. Description of the Related Art Conventionally, an image stabilizing device for a TV lens has a vibration-proof lens movably supported in a lens barrel of the TV lens in a plane orthogonal to a photographing optical axis. The image stabilization lens is moved by an actuator in a direction to cancel the vibration to prevent image blur. The detection of the vibration applied to the camera is performed by a vibration speed sensor (angular speed sensor or speed sensor) installed in the camera body or the lens barrel.

In controlling an image stabilizing lens in a camera having such an image blur prevention mechanism, Japanese Patent Laid-Open No.
Japanese Patent Publication No. 118469 proposes a method of appropriately removing a correction error due to a drift (a phenomenon in which the output of the sensor changes with time) of a vibration speed sensor that detects vibration applied to a camera.

[0004]

Conventionally, when controlling the position of an anti-vibration lens, vibration applied to a camera is detected by a vibration speed sensor, and the position of the anti-vibration lens is obtained based on the sensor output. However, at that time, there has been a problem how to control the image stabilizing lens at the center of the movable range (origin position) with respect to the sensor output.

That is, the position of the image stabilizing lens corresponds to the integral value of the sensor output. When the integrated value becomes zero, the position of the image stabilizing lens is controlled so as to be at the center of the movable range, that is, at the origin position. You. However, the integration value differs depending on the starting point of the integration, and the time when the integration value becomes zero also differs depending on when the starting point of the integration is made. Accordingly, the range in which the image stabilizing lens operates (operating range) is also different based on the integrated value. For this reason, the center of the operating range of the anti-vibration lens with respect to vibration does not always coincide with the center of the movable range (origin position) of the anti-vibration lens. On the other hand, there is a large deviation in only one direction, and the operating range of the anti-vibration lens is restricted by the mechanical end, so that the anti-vibration function cannot be fully exhibited. Originally, it is desirable that the center of the operating range of the anti-vibration lens is located at the origin position. At this time, the anti-vibration function can be maximized. Japanese Patent Application Laid-Open No. 6-118469 does not describe how to control the image stabilizing lens at the origin position with respect to the sensor output.

Further, considering the case where noise and drift components are included in the sensor output, those components are accumulated in the integrated value of the sensor output. In such a case, even if the center of the operation range of the anti-vibration lens with respect to the vibration is initially set appropriately at the origin position as described above, the center of the operation range of the anti-vibration lens gradually shifts from the origin position. As a result, a situation occurs in which the anti-vibration function does not work properly.

The present invention has been made in view of such circumstances, and the center of the operating range of the anti-vibration lens with respect to the vibration applied to the camera is appropriately set at the center of the movable range (origin position) of the anti-vibration lens. In addition, an object of the present invention is to provide an image blur prevention device capable of removing an adverse effect due to noise or the like included in an output of a vibration speed sensor and appropriately preventing image blur.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image blur prevention apparatus for preventing image blur caused by camera vibration by driving a correction optical system, wherein the speed of the vibration is detected. A vibration speed detecting means, a differentiating means for obtaining a differential value of the speed detected by the vibration speed detecting means, an integrating means for obtaining an integral value of the speed detected by the vibration speed detecting means, and the differential means. Correction means for correcting the integrated value obtained by the integration means to zero when the differentiated value is zero, and control means for controlling the position of the correction optical system based on the integrated value obtained by the correction means. , Is provided.

According to the present invention, the velocity of the vibration applied to the camera is detected, the differential value and the integral value of the velocity are obtained, and the integral value when the differential value becomes zero is set to zero. Since the position of the correction optical system is controlled by the integrated value, the center of the operation range of the correction optical system with respect to vibration can be appropriately set at the origin position, and included in the output signal of the vibration speed detection means. Adverse effects due to noise and the like can be eliminated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an image blur prevention device according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of an image blur prevention apparatus according to the present invention. The image blur prevention device is mounted on, for example, a lens device for a television camera, a movie camera, or a still camera. The image stabilizing lens 10 illustrated in FIG. It is arranged movably up and down, left and right within the lens barrel. The anti-vibration lens 10 is driven by a motor 12, and when a camera (a lens barrel) is vibrated, a position where image blur is prevented by the motor 12 (a position where the vibration is canceled). ) Is driven. Note that the anti-vibration lens 10 is provided with a motor that drives the anti-vibration lens 10 in the vertical and horizontal directions in a plane parallel to the optical axis.
Since the anti-vibration lens 10 is driven by the same control in any direction based on the vibration generated in each direction,
FIG. 1 shows only the motor 12 for driving the anti-vibration lens 10 in any one direction. In the following description, only the case where the anti-vibration lens 10 is driven in one direction will be described.

The angular velocity sensor 14 shown in FIG.
It is used as a vibration speed sensor for detecting the speed of vibration of the lens barrel, and detects the angular speed of vibration as the speed of vibration. Note that a velocity sensor may be used instead of the angular velocity sensor. The angular velocity sensors 14 are installed on the upper and side surfaces of the lens barrel, detect the angular velocity of vertical vibration and the horizontal velocity of the lens barrel, and output an electric signal of a voltage corresponding to the detected angular velocity. I do. In FIG. 1, for simplicity, only the angle sensor 14 that detects only the angular velocity of vibration in one of the vertical direction and the horizontal direction is shown. It is assumed that the angular velocity of the vibration is detected.

The CPU 16 shown in FIG. 1 obtains the electric signal output from the angular velocity sensor 14 via the A / D converter 18 to obtain the angular velocity of the vibration applied to the lens barrel. Then, based on the angular velocity of this vibration, the position of the anti-vibration lens 10 for preventing image blur is obtained,
A position command signal for commanding movement to the position is output to the motor drive circuit 22 via the D / A converter 20.

The motor drive circuit 22 detects the position of the anti-vibration lens 10 by using the potentiometer
Motor 1 based on the position command signal given from U16.
2 to move the anti-vibration lens 10 to a position designated by the position command signal.

Next, the processing contents of the CPU 16 will be described. As shown in FIG. 2, the CPU 16 performs a differentiation process and an integration process on the angular velocity of the vibration acquired from the angular velocity sensor 14, obtains a differential value and an integral value of the angular velocity, and corrects the integral value based on the differential value. Anti-vibration lens 1
The position of 0 is obtained.

Here, the differentiation process is performed by incrementing the angular velocity ω of the vibration obtained from the angular velocity sensor 14 at a predetermined time interval Δt.
This is a process for obtaining a value obtained by dividing ω by Δt. Note that simply Δω
May be a differential value. On the other hand, the integration process is based on the angular velocity ω of the vibration acquired from the angular velocity sensor 14 at a predetermined time interval Δt.
Is a process of sequentially adding values obtained by multiplying by Δt.
It should be noted that a value obtained by simply adding the angular velocity ω of the vibration obtained at the predetermined time interval Δt may be used as the integral value.

As shown in FIG. 3 (A), if the angular velocity ω of the vibration is expressed by the equation ω = A · SIN Bt (1) (where A and B are constants and t is time), Differential value of angular velocity d obtained by processing
ω / dt becomes dω / dt = A · B · COS Bt (2), and as shown in FIG. 3B, the time points (t1, t3, t5,...) at which the angular velocity reaches the maximum value and the minimum value. , The differential value becomes zero.

On the other hand, the integral value of the angular velocity 角 ωdt obtained by the integration process is given by す る と ωdt = −A / BCOS Bt + A / BCOS Btx (3) where the integration section is [tx, t], and the start of the integration section The integrated value ∫ωdt is oscillated by the first term on the right side around the value of the second term on the right side corresponding to the point tx. If the second term on the right side is 0, the integrated value ∫ωdt oscillates positive and negative around 0.

The integral value of the angular velocity indicates the position (displacement amount from the origin position) of the anti-vibration lens 10 for preventing image blurring with respect to the detected vibration. The value obtained by performing a process such as multiplying the magnification may be used as the position of the anti-vibration lens 10.) The first term on the right side of the equation (3) indicates the vibration operation of the anti-vibration lens 10 for preventing the image blur. The second term on the right side shows the anti-vibration lens 1 according to the first term.
The position of the center of the operation range of 0 (hereinafter referred to as the amplitude center) is shown. The anti-vibration lens 10 shown in the second term on the right side
It is most preferable that the amplitude center of
It is desirable that the second term on the right side be zero, but for that purpose, it is necessary to appropriately set the start point tx of the integration section. When the value of the constant B is determined, tx at which the second term on the right side is zero is also determined. However, since the value of B differs depending on the vibration applied to the lens barrel, it cannot be determined uniformly. In addition, the value of B can be obtained based on the cycle of the angular velocity ω. In this case, however, it cannot be determined that the change in the angular velocity does not exceed a half cycle at least. However, the starting point tx at which the second term on the right side of the equation (3) is zero can be easily obtained by referring to the differential value of the equation (2).

That is, when the differential value becomes zero, the value of COS Bt is zero. By setting this time as the starting point tx of the integration section, the second term on the right side of the equation (3) is made zero. Can be. Actually, setting the start point tx of the integration section is equivalent to correcting the integrated value obtained by starting the integration process at an arbitrary time to a value of zero. By correcting the integral value to 0 when it is detected that the differential value has become zero, the center of the amplitude of the anti-vibration lens 10 can be made to coincide with the origin position as shown in FIG.

The CPU 16 obtains the differential value and the integral value of the angular velocity by the differentiation process and the integration process as described above, and when the differential value becomes zero, corrects the integral value to zero. To determine the position of the anti-vibration lens 10.
As a result, as described above, the amplitude center of the image stabilizing lens 10 is appropriately set at the origin position, and the operation range of the image stabilizing lens 10 is maximized without the operating range being restricted by the mechanical end. . Since the differential value of the angular velocity of the vibration obtained by the differential processing is the angular acceleration, an angular acceleration sensor may be used without performing the differential processing. However, such an angular acceleration sensor is required by calculating. Cost can be reduced.

If the signal output from the angular velocity sensor 14 contains noise and drift components, these components are accumulated in the integrated value, and first, as described above, Even if the amplitude center is made to coincide with the origin position, there occurs a phenomenon that the amplitude center gradually shifts from the origin position. Also, when the cycle of vibration applied to the lens barrel changes, the center of the amplitude of the anti-vibration lens 10 shifts from the origin position. Therefore, the CPU 16 corrects the integral value to zero each time the differential value becomes zero, and also corrects a shift caused by noise or a change in vibration state. However, this process does not necessarily need to be performed every time the differential value becomes zero, and may be performed only when the integral value is shifted from the origin position by a predetermined value or more when the differential value becomes zero. In addition, the vibration control may be performed only when the amplitude center of the image stabilizing lens 10 deviates from the origin position, whereby the amplitude range of the image stabilizing lens is restricted by the mechanical end, and it becomes impossible to appropriately perform image stabilization. Good. Further, instead of correcting the integral value to zero at one time when the differential value becomes zero, the integral value may be corrected to gradually approach zero so that the correction does not affect the captured image. By performing such processing, it is possible to appropriately prevent a situation in which the amplitude center of the image stabilizing lens 10 deviates from the origin position due to noise and drift components included in the output of the angular velocity sensor 14 and changes in vibration applied to the lens barrel. You.

FIG. 4 is a flowchart showing a processing procedure of the CPU 16. CPU 16 is an angular velocity sensor 1
From step 4, the angular velocity of the vibration is acquired at predetermined time intervals (step S10). Then, based on the obtained angular velocity, an integral value and a differential value of the angular velocity are obtained (Step S12, Step S14). Next, it is determined whether the differential value has become zero (step S16). Thereby, YES, that is,
If it is determined that the differential value has become zero, the integral value is corrected to zero (step S18). On the other hand, if NO, the integrated value is not corrected. The above process is repeatedly executed, and a position command signal for commanding the position of the anti-vibration lens 10 based on the integrated value is output to the motor drive circuit 22.

As described above, in the above-described embodiment, the angular velocity sensor is used as the vibration velocity sensor for detecting the velocity of the vibration. However, the velocity sensor may be used instead of the angular velocity sensor. The contents are exactly the same.

In the above embodiment, the case where the image blur is prevented by the anti-vibration lens specially arranged on the lens barrel has been described. However, the present invention drives any correction optical system to prevent the image blur. The present invention can be applied to all anti-shake devices.

[0026]

As described above, according to the image blur prevention apparatus of the present invention, the speed of the vibration applied to the camera is detected, the differential value and the integral value of the speed are obtained, and the differential value is set to zero. Set the integral value when it becomes to zero,
Since the position of the correction optical system is controlled by the integrated value, the center of the operating range of the correction optical system with respect to vibration can be appropriately set at the origin position, and noise included in the output signal of the vibration speed detection means can be set. And the like. Therefore, the operation range of the correction optical system is maximized, and the image blur prevention function is maximized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an image blur prevention apparatus according to the present invention.

FIG. 2 is an explanatory diagram illustrating processing contents of a CPU;

FIGS. 3A, 3B, and 3C are diagrams showing the relationship among the angular velocity of vibration, the differentiation of angular velocity, and the integration of angular velocity, respectively.

FIG. 4 is a flowchart illustrating a processing procedure of a CPU;

[Explanation of symbols]

10 anti-vibration lens, 12 motor, 14 angular velocity sensor, 16 CPU, 22 motor drive circuit

Claims (1)

[Claims] 1. An image blur prevention apparatus for preventing an image blur caused by a camera vibration by driving a correction optical system, wherein the vibration speed detecting means detects the speed of the vibration, and the vibration speed is detected by the vibration speed detecting means. A differentiating means for obtaining a differential value of the velocity; an integrating means for obtaining an integral value of the velocity detected by the vibration velocity detecting means; and a differential value obtained by the integrating means when the differential value obtained by the differentiating means is zero. An image blur prevention apparatus, comprising: a correction unit that corrects an integral value to zero; and a control unit that controls a position of the correction optical system based on the integral value obtained by the correction unit.