JPH04163533A - Camera shake compensator - Google Patents

Abstract

PURPOSE:To secure such a screen image that is completely stopped even to a slow movement by detecting an amount of parallel travel per unit time of a succeeding image to the preceding image from the image data and an angular speed within the low angular speed range of a camera on the basis of this parallel travel. CONSTITUTION:As an angular speed detecting means available for a mechanical deflection compensating means 51, two types of first and second angular speed detecting means 39, 55 are made so as to be used. In brief, the first angular speed detecting means 39 is one that detects an angular speed concerned when the angular speed attending on the deflection of a camera. While the second angular speed detecting means 55 is one that detects an amount of a parallel travel per unit time of a succeeding image to the preceding image on the basis of image data between respective fields and also detects the angular speed of the camera on the basis of this parallel travel. Moreover, the mechanical deflection compensation means 51 is made so as to utilize two detection output data of both these first and second angular speed detecting means 39, 55. With this constitution, such a screen image that is completely stopped even to a slow movement can be secured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image stabilization device, and particularly to an image stabilization device that drives at least a part of the optical members of a photographic optical system of a camera to prevent the light from entering the image plane through the photographic optical system. The present invention relates to an image stabilization device for a camera that stabilizes subject light.

[Conventional technology]

Conventionally, image stabilization devices for cameras have been provided with a tiltable correction mirror having an angle of approximately 45° with respect to the optical axis of the photographic lens, and the image stabilization device is driven to move the image stabilization through the correction mirror and the photographic lens. A device that stabilizes the subject light incident on the imaging surface, and a gimbal mechanism that supports the entire photographic lens or a part of the photographic lens so that it can tilt freely, and drives this supported lens to stabilize the photographic surface. There are things that stabilize the subject light that enters the camera.

An angular velocity sensor that detects camera shake used in this type of mechanical image stabilization device generally uses Coriolis force.

[Problem to be solved by the invention]

By the way, although the Kamikimi angular velocity sensor outputs a voltage signal proportional to the angular velocity, it has been difficult to detect a small angular velocity (for example, 1°/sec) because the Coriolis force itself is small. Therefore, mechanical image stabilization devices using such angular velocity sensors are highly effective in correcting shakes with large angular velocities, but cannot satisfactorily correct shakes with small angular velocities (slow movements).

The present invention was made in view of these circumstances, and is capable of detecting small angular velocities, which are difficult for general angular velocity sensors used in mechanical image stabilization devices, and can completely stop even slow movements. An object of the present invention is to provide an image stabilization device that can obtain a sharp image.

[Means for solving the ode: In order to achieve the above object, the present invention provides a first angular velocity sensor that detects the angular velocity by adding the angular velocity associated with camera shake, and an image between each field. a second angular velocity detection means for detecting the amount of parallel movement per unit time of the subsequent image with respect to the preceding image based on the data, and detecting the angular velocity of the camera based on the amount of parallel movement; Mechanical image stabilization means for movably disposing at least a part of the optical member and driving the optical member based on outputs from the first and second angular velocity detection means. do.

[Function] According to the present invention, two types of angular velocity detection means, first and second, are used as the angular velocity detection means used in the mechanical image stabilization means.

That is, the first angular velocity detection means detects the angular velocity by adding the angular velocity due to camera shake, and the second angular velocity detection means detects the subsequent angular velocity with respect to the preceding image based on the image data between each field. The amount of translation per unit time of the image is detected, and the angular velocity of the camera is detected based on this amount of translation. The mechanical image stabilization means utilizes two detection outputs from the first and second angular velocity detection means. Therefore,
Both the first and second angular velocity detection means can be used properly for each angular velocity range in which they are respectively good.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the image stabilization device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a video camera equipped with an image stabilization device according to the present invention.
0 is provided.

As shown in FIG. 1, object light enters a solid-state image sensor (CCD) 22 via a correction mirror 10 and a photographing lens 20, and each sensor of the CCD 22 converts the signal charge into an amount corresponding to the intensity of the light. converted.

The second signal charges are sequentially read out and sent to the A/D converter 34 via a sample hold circuit 30 and an automatic gain control circuit 32.
is output to.

The A/D converter 34 converts the input analog signal into a digital signal (image data) and outputs it to the signal processing circuit 42 as well as to the memory 37 and the motion detection circuit 39.

The signal processing circuit 42 performs signal processing such as white balance correction on manually generated image data, and then transmits the signal processing to the D/A converter 4.
6 to the recording device 48. The recording device 48 includes a recording signal processing circuit, converts the video signal manually input from the D/A converter 46 into a recording signal suitable for magnetic recording, outputs this to a magnetic head, and magnetically records it on a video tape.

The memo υ 37 stores image data of a predetermined motion detection area within the l field, delays this by one field period, and outputs it to the motion detection circuit 39.

The motion detection circuit 39 receives image data in the motion detection area of the current field and 1 added via the memory 37.
The image data in the motion detection area of the field before the field is compared, and the direction and amount of motion between fields (difference motion vector) are determined. This differential motion vector is calculated by performing a correlation calculation on each image data in the motion detection area of the previous and subsequent fields, and calculating the shift amount (
Calculated from the amount of parallel movement of the screen.

Then, the differential motion vector between each field obtained in this way, that is, per unit time (1 field period)
Vector information indicating the amount of parallel movement of is output to the arithmetic circuit 50.

The arithmetic circuit 50 inputs the upper vector information and also
From the zoom encoder 24 to the variable magnification unit 20 of the photographic lens 20
The zoom information indicating the movement position of Δ (zoom position) is manually generated, and the angular velocity in the pan direction (X direction) and tilt direction (Y direction) of the video camera is calculated based on the above vector information, zoom information, and sampling period. Then, a signal indicating this angular velocity is output to the mirror control circuit 52 of the mechanical image stabilization section 51.

Next, the mechanical image stabilization section 51 of this video camera will be explained. The mechanical image stabilization unit 51 mainly includes a correction mirror lO, a first bimorph driver, a mirror control circuit 52, a mirror drive circuit 54, and an angular velocity sensor 55.

First, the drive mechanism of the correction mirror 10 will be briefly explained.

In FIG. 2, the correction mirror 10 is glued to the mirror base plate 12, and the mirror base plate 12 is attached to the mirror 715 with the ball 13 interposed by four leaf springs 14 (only one is shown in FIG. 2). It is pressed and maintained in a neutral position parallel to the chassis 15 by the biasing force of the leaf spring 14. Thereby, the mirror base plate 12, that is, the correction mirror 10 is supported so as to be tiltable in all directions with respect to the chassis 15.

One end of the first bimorph driver is fixed to the chassis 15, and a drive member 16 having a drive bin 16A is attached to the other end. A coil spring 17 is disposed between the drive member 16 and the mirror base plate 32, so that the tip of the drive pin 16A is always in contact with an abutment base 18 planted on the mirror base plate 12.

According to the mirror drive mechanism configured as described above, when the first bimorph driver is driven and its tip is displaced, the drive member 16
is moved in the direction shown by the arrow in FIG. 2, thereby changing the gap between the yarn 15 and the correction mirror 10. That is, the correction mirror 10 is tilted with the center of the ball 13 as a reference.

Next, the control system of the first bimorph driver will be explained.

The mirror control circuit 52 is configured to receive signals from the angular velocity sensor 55 and the arithmetic circuit 50 described above.

The angular velocity sensor 55 is, for example, a tuning fork type angular velocity sensor,
The twisting of the tuning fork due to the Coriolis force corresponding to the angular velocity is detected, and a voltage signal proportional to the twisting (speed regulating &) is output to the mirror control circuit 52. As shown in FIG. 3(A), the angular velocity sensor 55 Within the low angular velocity range that cannot be detected (±ω
a) For example, a dead zone is provided for output within 1°/sec.

On the other hand, the arithmetic circuit 50 outputs a signal indicating the angular velocity only when the calculated angular velocity is within the low angular velocity range (:ωa) as shown in FIG. 3(B).

The mirror control circuit 52 calculates the two signals applied from the angular velocity sensor 55 and the arithmetic circuit 50. For example, it simply adds the two signals, and then multiplies the two signals by a certain ratio and adds them. This is used as an angular velocity signal and is manually input in a constant cycle. Then, a pulse rate proportional to the magnitude of the angular velocity signal (angular velocity) is determined, and a pulse signal of this determined pulse rate is output to the mirror drive circuit 54 until the next angular velocity signal is input. As a result, a pulse having a pulse rate proportional to the angular velocity is applied to the mirror drive circuit 54.

The mirror drive circuit 54 amplifies the manually inputted pulse signal and injects charge into the first bimorph driver.

That is, the mirror drive circuit 54 injects pulse charges of a constant size at intervals corresponding to the pulse rate of the input pulse signal.

As a result, an amount of charge proportional to the angular velocity is injected into the first bimorph driver, and the first bimorph driver is displaced in proportion to the amount of charge injected, thereby tilting the correction mirror 10.

Also, if the sign of the input angular velocity signal is reversed,
The polarity of the pulse signal output from the mirror control circuit 52 is also reversed, and the first bimorph driver is displaced in the opposite direction.

Since the above-mentioned operations are repeatedly executed at short intervals, the correction mirror 10 tilts at an angular velocity proportional to the angular velocity of the video camera, thereby stabilizing the subject light incident on the photographing lens 20. However, the gain of the mirror drive circuit 54 and the like are adjusted in advance so that the correction mirror 10 is tilted in the opposite direction at an angular velocity that is half the calculated angular velocity.

In this embodiment, the mechanical image stabilization unit 51 has been explained in terms of only one system in the X direction or the Y direction.
It has two independent control systems that perform camera shake correction in the direction and Y direction. Further, the mechanical image stabilization device is not limited to one using the correction mirror of this embodiment, and the control method thereof is not limited to this embodiment, and various methods can be considered.

1: Effects of the Invention As explained above, according to the image stabilization device according to the present invention, the amount of parallel movement per unit time of the subsequent image with respect to the preceding image is detected from image data, and the amount of parallel movement is detected based on this amount of parallel movement. Since the angular velocity of the camera is detected in the low angular velocity range, it is possible to accurately detect the angular velocity range that cannot be detected by the angular velocity sensor used in mechanical image stabilization devices. It is possible to achieve completely stopped image stabilization.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a video camera equipped with an image stabilization device according to the present invention, FIG. 2 is a sectional view showing details of a mirror drive mechanism of the mechanical image stabilization unit in FIG. 3A and 3B are graphs showing examples of the outputs of the angular velocity sensor and the arithmetic circuit shown in FIG. 1, respectively. DESCRIPTION OF SYMBOLS 10... Correction mirror, 1st... Bimorph driver, 20... Taking lens, 2OA... Magnification variable part,
22... Solid-state imaging device (CCD), 24... Zoom encoder, 39... Motion detection circuit, 37... Memory, 50... Arithmetic circuit, 5
DESCRIPTION OF SYMBOLS 1... Mechanical image stabilizer, 52... Mirror control circuit, 54... Mirror drive circuit, 55... Angular velocity sensor.

Claims (3)

[Claims] (1) A first angular velocity sensor that detects the angular velocity by adding the angular velocity associated with camera shake, and the amount of parallel movement per unit time of the subsequent image relative to the preceding image based on image data between each field. and a second angular velocity detection means for detecting the angular velocity of the camera based on the amount of parallel movement, and at least a part of the optical member of the photographing optical system of the camera are movably disposed, and the optical member is arranged to be movable. 1st
and a mechanical image stabilization means that is driven based on the output from the second angular velocity detection means. (2) The second angular velocity detection means includes a detection means for detecting the focal length of the photographing lens, and an arithmetic means for calculating the angular velocity of the camera based on the amount of parallel movement per unit time and the detected focal length. An image stabilization device according to claim (1). (3) The image stabilization device drives the optical member based on the output of the first angular velocity detection means when the detected angular velocity is greater than or equal to a predetermined angular velocity, and drives the optical member based on the output of the first angular velocity detection means when the detected angular velocity is less than or equal to the predetermined angular velocity. Claim (1) or (2) characterized in that the optical member is driven based on the output of
) image stabilization device.