JPH0690398A - Image blur correction device - Google Patents

Abstract

PURPOSE:To solve effectively aberration of distortion caused by eccentricity being a defect of a prism by forming the device with a means converting an optical image into an electric signal and a processing circuit correcting the aberration of distortion caused in the image when a blur of an image caused in an objective lens is corrected optically. CONSTITUTION:The vibration preventing system employing a variable apex angle prism is made up of a variable apex prism 1 as an image blur correction means, an image pickup lens system 2, an image pickup element 3 such as a CCD converting an optical image into an electric signal, a circuit 4 processing the signal from the element, a sensor 5 detecting a blur of a video camera including the optical system, and a sensor 6 detecting a turning angle in each direction of a yoke and pitch of the prism. In such a constitution, a vibration prevention on/off switch (not shown) is used after turning on of power source to discriminate whether or not the mode is in the vibration prevention mode, the usual operation is performed as it is when the mode is not the vibration prevention mode, a current prism turning angle is calculated from the sensors 5, 6 when it is in the vibration prevention mode and the aberration of distortion is calculated from the zoom position and the turning angle is obtained from an encoder 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera device such as a video camera having an anti-vibration lens using a variable apex angle prism device capable of arbitrarily changing the traveling direction of a passing light beam.

[0002]

2. Description of the Related Art In recent years, automation of camera devices such as video cameras has progressed, and various functions such as automatic exposure adjusting means and automatic focus adjusting means have been put to practical use.

With these automation functions as one, a blur correction means for reducing harmful blur of the screen caused by various causes has been devised and put into practical use.

Particularly in a camera device such as a video camera, it is general to use a zoom lens as a photographing lens used, and the zoom ratio thereof tends to increase year by year. On the other hand, the downsizing of camera devices is also remarkable, and due to the downsizing of the image pickup screen, the development of high-density mounting technology, and the development of a small recorder mechanical chassis, small models capable of shooting with one hand have appeared.

However, when using a small video camera equipped with such a zoom lens, harmful blurring of the screen occurs due to camera shake of the photographer, and in order to eliminate this blurring and obtain a stable screen. , Various blurring prevention means have been proposed. If you use these shake prevention measures,
Not only the harmful blurring of the screen due to such camera shake,
It is needless to say that it has a great effect even in a situation in which harmful camera shake cannot be removed by using a tripod when photographing from a ship or an automobile.

[0006] The blur prevention means includes at least blur detection means for detecting blur and blur correction means for performing some correction so that blur does not occur on the screen according to the detected blur information. ing.

As the shake detecting means, for example, an angular accelerometer, an angular velocity meter, an angular displacement meter, etc. are known.

As the blur correction means, a variable apex angle prism by the same applicant of the present application is used, or a video camera configured to cut out an area to be actually used as a screen from the obtained imaging screen information. A method is known in which the cutout position is sequentially changed to a position where blurring is corrected.

As the correction means, a method of removing blurring at the stage of an image formed on an image pickup element by using a variable apex angle prism or some other optical means as the correction means is used here. A method of electronically processing image information including a blur and removing the blur is called electronic correction means.

In general, the optical correction means is capable of correcting a blur within an angle defined as a blur angle of a camera regardless of the focal length of the lens, and therefore, the telephoto side of the zoom lens can be corrected. Even if the focal length is long,
It is possible to have a blur removal performance that poses no practical problem.
However, it has the drawback of becoming large.

On the other hand, the electronic correction means has a constant correction rate for the vertical dimension of the screen, for example. Therefore, the blur removal performance deteriorates as the focal length on the telephoto side becomes longer. In general, the electronic type is often advantageous for miniaturization.

FIG. 8 is a diagram for explaining the relationship between the focal length and the camera shake angle by the subject position on the screen. In the figure, when the camera is at the position indicated by 22, the optical axis of the lens is 23, which means that the face of the person 21, who is the subject, is almost centered. It is assumed that the camera rotates by a degree from this state due to camera shake. The camera position at this time is 24
, The optical axis is indicated by 25.

8B and 8C show the screen positions at the camera positions indicated by 22 and 24 in FIG. 8, and FIG. 8B shows the state at the telephoto end of the zoom lens. )
Indicates the state at the wide end. Reference numeral 26 denotes a subject within the screen, 27 and 29 denote the screen at the 22 position, and 28 and 20 denote the screen at the 24 position.

As is clear from FIG. 9, even with camera shake of the same a degree, the longer the focal length of the lens is, of course, more harmful as the shake on the screen. Therefore, it can be said that an optical means using a variable apex angle prism is an effective blur correction means particularly in the blur removal means combined with a lens having a long focal length at the telephoto end.

FIG. 9 shows the structure of the variable apex angle prism. In the figure, 31 and 33 are glass plates, and 37 is a bellows portion made of a material such as polyethylene. A transparent liquid 32 made of, for example, silicon oil is enclosed inside the glass plate and the bellows.

In FIG. 9B, two glass plates 31 and 33 are provided.
Are parallel to each other, and in this case, the incident angle and the outgoing angle of the light beam of the variable apex angle prism are equal. On the other hand, FIG.
When there is an angle as in (C), the light rays 34,
The rays are bent at an angle, as indicated at 36. Therefore, when the camera is tilted due to camera shake or the like, the angle of the variable apex prism provided in front of the lens is controlled so that the spectral line corresponding to that angle bends,
Blur can be removed.

FIG. 10 shows this state.
Assuming that the variable apex angle prism is in a parallel state in (A) and the optical axis captures the head of the subject, as in (B),
By driving the variable apex angle prism as shown in the figure to bend the light beam against the fluctuation of the degree, the photographing optical axis remains unchanged and the subject's head can be continuously captured.

FIG. 12 is an exploded perspective view of a variable apex angle prism unit and the like including the variable apex angle prism, an actuator section for driving the variable apex angle prism, and an apex angle sensor for detecting an angular state. Actual blurring appears in all directions, but in order to deal with this, the front glass surface and the rear glass surface of the variable apex angle prism are configured to be rotatable about axes that are offset by 90 degrees. . Here, components having the same function are denoted by the same reference numerals, but subscripts a and b indicate components that are offset by 90 degrees. Note that some of the parts on the b side are not shown.

Reference numeral 51 denotes a main body of the variable apex angle prism, which is made of a glass plate 31, 33, a bellows portion 37 and a liquid such as silicon oil inside. The glass plate is integrally attached to the holding frame 38 using an adhesive or the like. The holding frame 38 is rotatable around a rotation shaft 43 with a fixed component (not shown). As described above, the shaft 43a and the shaft 43b are
90 degree direction is different. The coil 4 is placed on the holding frame 38.
5 is integrally provided, and a magnet 46 and yokes 47 and 48 are provided on a fixed portion (not shown). Therefore, the variable apex angle prism is rotated around the axis 43 by passing a current through the coil. There is a slit 39 at the tip of an arm portion 40 that extends integrally from the holding frame 38, and a light emitting element 4 such as an iRED element provided in the fixed portion.
1 and a light receiving element such as PSD, which constitutes a vertical angle sensor, detects the deviation state of the prism.

FIG. 11 shows a block diagram of an image stabilization control system in which the shake prevention means having the variable apex angle prism as a correction means is combined with a photographing lens.

In the figure, 51 is a variable apex angle prism, 5
Reference numerals 3 and 54 denote apex angle sensors 63 and 64 having the above-described configuration, detection circuit units for amplifying the outputs of the apex angle sensors, 55 a microcomputer, and 56 and 57 blurring detecting means.
In the microcomputer 55, in order to control the angle state of the variable apex angle prism to the angle state detected by the apex angle sensor and the optimal angle state for removing the blur according to the detection result of the blur detecting means 56, 57. , Determine the current to be applied to the actuators 58 and 59.

The main element is made up of two blocks because it is assumed that control in two directions 90 degrees apart is performed independently.

If the refractive index of the variable apex prism is n, the apex angle of the prism is σ, and the angle between the incident light beam and the outgoing light beam is δ, the following equations apply in the range of small apex angles.

Δ = (n−1) σ For example, in the case of n = 1.4, when the variable apex angle prism is tilted by 5 degrees, the light beam is bent by 2 degrees.

The blur prevention means using the variable apex angle prism has been described above.

[0026]

However, in the correction optical unit for optically correcting the image blur, particularly in the image stabilization optical system using the variable apex angle prism, when the image is deflected, that is, the apex angle is changed. There is a drawback in that eccentric distortion aberration occurs when it is caused. The explanation will be given below.

FIGS. 3 and 4 are views showing how decentering distortion occurs in the variable apex angle prism. FIG. 3 shows the axial chief ray 16 and the off-axis chief rays 17, 18 when the object side of the two transparent members of the variable apex angle prism 14 is inclined by σ due to the rotation perpendicular to both the optical axis and the paper surface. It shows the situation. Now, assume that the rotation direction in the plane of the drawing is the pitch direction, and the variable apex angle prism is controlled so that the axial chief ray 16 is δ-deflected according to the camera shake in the pitch direction (according to the formula described in the section of the prior art). Then, the off-axis chief rays with the angle of view ω in the taking lens system are incident on the variable apex angle prism at angles of φ1 and φ2, respectively. If the deflection angle (φ-ω) is constant within the entire screen and is equal to δ, the image is deflected while maintaining its original shape on the image plane, but in reality, φ depends on the angle of view of the taking lens system.
However, as a result, the deflection angles of the principal rays are different, and when the same object is photographed, the size on the image plane is not uniform.
This is distortion due to decentering.

In the case of FIG. 3, (φ2'-ω) is (φ1'-
ω), the image of the subject as shown in FIG. 7A is distorted into the shape as shown in FIG. 7B. The dotted line is an ideal image when there is no distortion.

Therefore, in the image stabilizing optical system for correcting the image blur caused by the camera shake by deflecting the image in the opposite direction by the variable apex angle prism, when the eccentric distortion aberration as described above is present, the point at the center of the screen and the axis are corrected. Since the amount of movement differs at outside points, image blurring occurs at the periphery even if the image blurring at the center of the screen is corrected. FIG. 7C shows the result of image blur correction of the subject as shown in FIG. 7A by the image stabilization optical system having such an eccentric aberration coefficient.

In view of this problem, it is an object of the present invention to provide a video camera having a high optical performance, in which distortion aberration generated particularly in a vibration-proof optical system is properly corrected.

A feature of the present invention is that, in a correction device having a correction means for optically correcting a blur of an image formed by an objective lens, a conversion means for converting the optical image into an electric signal, and the correction means. And a processing circuit for processing the electric signal in order to correct the distortion aberration caused by the means.

[0032]

(Embodiment 1) FIG. 1 is a diagram showing a first embodiment of a vibration isolation system using a variable apex angle prism according to the present invention. 1 is a variable apex angle prism as image blur correction means, 2
Is a taking lens system, 3 is a CC for converting an optical image into an electric signal
Image pickup device such as D, 4 is a signal processing circuit for processing a signal from the image pickup device, 5 is a shake detection sensor for detecting shake of a video camera including an optical system, 6 is a yoke of a variable apex angle prism, and directions of respective pitches Sensor that detects the rotation angle of
7 is a device for driving the variable apex prism 1 by the deflection angle calculated by the control circuit 8 according to the information of the sensors 5 and 6, and 9 is a zoom position (focal length) of the taking lens system. Encoder for detecting
Is a distortion aberration calculation circuit that calculates the distortion aberration that will be generated based on the output of the rotation angle sensor 6 and the output of the encoder 9, and 11 is the signal processing circuit 4 based on the result of the distortion aberration calculation circuit 10. It is a processing circuit that performs signal processing so as to correct distortion for output.

Next, the operation will be described according to the flow shown in FIG. First, after the power is turned on (# 001), it is determined whether or not the image stabilization mode is set by detecting an image stabilization on / off switch (not shown) or the like (# 002). When not in the image stabilization mode, the normal operation is performed and the operation returns to the beginning.
In the image stabilization mode, after obtaining the shake amount information from the shake detection sensor and the current variable apex angle prism rotation information from the rotation angle sensor 6, (# 003) the variable apex angle prism required for image stabilization. The rotation angle is calculated (# 004). Next, 9
Zoom position (# 00
From 5) and the calculated required variable apex angle prism rotation angle, the value of the distortion aberration that may occur on the imaging surface is calculated according to the formula described later (# 006). Here, it is determined whether or not the distortion aberration correction is performed depending on whether the calculated value of the distortion aberration is within the allowable range (# 007). If it is determined that the distortion aberration correction is not performed, the normal blur correction operation is performed ( # 012), return to the beginning. If the calculated distortion is large and exceeds the allowable range, distortion correction is performed,
In that case, first, normal blur correction is performed based on the information of the necessary variable apex angle prism rotation angle calculated previously. Then, the actual rotation angle of the variable apex angle prism at that time is read from the rotation angle sensor 6 (# 009), and the distortion aberration amount (distortion correction amount) is calculated together with the information of the zoom position encoder 9 (# 010). ) And 12, the distortion aberration correction circuit further processes the signal of the signal processing circuit 4 to correct the distortion aberration.

Next, the relationship between the rotation angle of the variable apex angle prism and the distortion aberration generated on the image pickup surface will be described with reference to FIGS. Although the case of tilting the variable apex angle prism only in the pitch direction was described in the section of the prior art with reference to FIG. 3, in actuality, in each cross section around the optical axis, both the yoke and pitch directions are combined to form as shown in FIG. There is. It should be noted that σ1 and σ2 are determined in relation to the screen aspect ratio depending on how much the yoke axis (pitch axis) is inclined. In FIG. 4, 14 is a variable apex prism having a simplified apex angle of object side σ1 and image plane side σ2, 15 is a taking lens system, 16 is an axial chief ray, and 17 and 1 are shown.
Denoted at 8 is an off-axis chief ray having an angle of view of ω in the taking lens system. If we define the angle of view through the variable apex angle prism centering on the axial principal ray that has been δ-deflected, it will differ at the top and bottom of the screen and will be ω1 'and ω2', respectively. ω1 ′ and ω2 ′ are the angle of view ω of the taking lens system and the apex angles σ1 and σ of the variable apex angle prism.
2. It is expressed as follows using the refractive index n of the liquid inside the variable apex angle prism. Letting the correction angle δ be δ = (n−1) · (σ1 + σ2), ω1 ′ = φ1 + δ, and φ1 is obtained by solving the following two equations: sin (ω + σ1) = n · sin (θ1 + σ1) n · sin (θ1 -[Sigma] 2) = sin ([phi] 1- [sigma] 2) [omega] 2 '= [phi] 2+ [delta] Then, [phi] 2 is obtained by solving the following two equations.

Sin (ω−σ1) = n · sin (θ2−σ1) n · sin (θ2 + σ2) = sin (φ2 + σ2) Furthermore, the relationship between the angle of view and the image height y ′ = f · tan ω is used.

[0036]

[Outer 1] Can be expressed as

Therefore, the amount of distortion aberration correction is determined with the angle of view, that is, the image height, the total focal length of the taking lens system, and the rotation angle of the variable apex angle prism as parameters. Therefore, the correction amount is determined by performing the calculation for each image height.

In the case of the first embodiment, the correction of the distortion aberration is always performed if the distortion aberration exceeds the allowable range. However, in the camera equipped with the known autofocus device, the screen is blurred when the focusing operation is performed. In the case of occurrence of distortion, it is desirable not to perform distortion correction until the in-focus state is reached. Therefore, as shown in FIG. 5, information about whether or not the taking lens is in focus operation is obtained from an autofocus circuit or the like,
During the focusing operation, the distortion aberration correction is not performed until the focal point is reached. The flowchart of FIG. 5 is that step # 020 is added to the flowchart of FIG. By doing so, the time required to correct the distortion aberration can be omitted, and the accuracy and speed of autofocus can be increased accordingly.

Further, in calculating the distortion aberration of the first embodiment, the calculation is carried out from the variable apex angle prism rotation angle and the zoom position. Normally, the loop of the flowchart shown in FIG. Since it is performed every / 60) seconds, there is a case where it takes too much time for calculation, and a calculation device (microcomputer or the like) for performing calculation becomes complicated. Therefore, in this embodiment, as shown in FIG. 6, the variable apex prism rotation angle and the amount of distortion aberration corresponding to the position on the image plane due to the zoom position are stored in advance in the storage device 13 as a table. In the actual operation, the method of calculating the amount of distortion aberration in the flow of FIG. 2 is replaced with the comparison with the stored table from the calculation.

[0040]

As described above, according to the present invention, in the image blur correcting apparatus using the variable apex angle prism, the image signal from the image sensor is processed for the distortion aberration generated in the variable apex angle prism. By doing so, it is possible to effectively solve the problem of distortion aberration due to decentering, which is a drawback of the variable apex angle prism.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an operation flowchart of the first embodiment of the present invention.

FIG. 3 Principle diagram of calculation of distortion aberration

FIG. 4 Principle diagram of calculation of distortion aberration

FIG. 5 is an operation flow chart of the second embodiment of the present invention.

FIG. 6 is a block diagram of a third embodiment of the present invention.

FIG. 7 is a diagram showing distortion aberration generated by a variable apex angle prism.

FIG. 8 is a diagram showing how image blurring occurs.

FIG. 9 is a diagram showing an operation of a variable apex angle prism for reducing image blur.

FIG. 10 is a diagram showing an operation of a variable apex angle prism for reducing image blur.

FIG. 11 is a diagram showing a block diagram of a control circuit for correcting image blur.

FIG. 12 is an exploded perspective view of a variable apex angle prism.

Claims (2)

[Claims] 1. An image blur correction device comprising correction means for optically correcting blur of an optical image formed by an objective lens, the conversion means converting the optical image into an electric signal, and the correction means. An image blur correction device comprising a processing means for processing the electric signal in order to correct distortion. 2. The processing means signal-processes the electric signal so as to change the correction amount of the distortion aberration in accordance with the focal length of the objective lens and the correction amount of the correction means.