JPH08313950A - Image shake preventing device - Google Patents

Abstract

PURPOSE: To always obtain a stable image, even if the correction value of a picture shake obtained with the output of a vibration detecting means is changed rapidly. CONSTITUTION: Time to increase the correction value (improve vibration proof performance) is set longer than time to reduce the correction value (deteriorate the vibration proof performance) by a time setting means 110. In other words, the time to return from a panning state or a tilting state to a normal vibration proof state is set longer to change the correction value based on the set time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of an image blur prevention device mounted on an optical device such as a video camera or binoculars, and more particularly, an image blur prevention device for preventing image blur during panning or tilting operation of the optical device. It relates to the device.

[0002]

2. Description of the Related Art Heretofore, high-magnification optical instruments such as monoculars and binoculars have been large in size, and most of them have been seen through a fixing means such as a tripod. However, due to the recent development of technology, miniaturization and higher magnification have been advanced, and the frequency of handheld use has been increasing. Especially for video movies, it is standard that the weight is less than 1 kg, so that even children can take pictures. In addition, the functions such as focus, wide-balance, and light amount adjustment have been automated, and their use has been dramatically accelerated.

On the other hand, due to the small size and high magnification, image deterioration due to camera shake has become a new problem, and research and development has progressed. For example, a pure electronic method that extracts the amount of camera shake from image data and selects the angle of view in the direction to correct the camera shake, an optical method that controls the correction optical system by calculating the camera shake amount from an angular velocity sensor equipped in the camera, , A product consisting of a combination of the former and the latter has been commercialized.

An optical image blur prevention device of the above-mentioned conventional devices will be described in detail with reference to FIG.

Since the image blur prevention device independently controls two camera shake orthogonal component signals such as horizontal and vertical, only one signal path will be described here.

In FIG. 7, 201 is a gyro,
The angular velocity signal 202 is output. 203 is the angular velocity signal 20
It is a high-frequency pass filter (hereinafter referred to as HPF) for removing a component close to a direct current contained in 2 and outputs a shake signal (about 1 Hz or more) 204. Reference numeral 205 denotes an integrating circuit that integrates the camera shake signal 204 and outputs an angular displacement signal 206. The angular displacement signal 206 indicates the direction in which an optical device such as a camera is facing.

Reference numeral 220 denotes a variable apex angle prism (hereinafter, VAP
The apex angle is changed by the mechanical drive 216, and the incident angle to the lens group 221 is changed. Two
Reference numeral 15 is an actuator for generating the mechanical drive 216. Reference numeral 217 is an arm for transmitting the movement of the VAP 220 to the apex angle sensor 218, which allows the apex angle sensor 2 to move.
At 18, a vertical angle signal 219 of the VAP 220 is generated.
209 is the apex angle signal 219 and the angular displacement signal 206 described above.
Is an adder for adding with a reverse polarity, and a difference (deviation) signal 210 is output from this adder. 210 is the difference signal 2
It is an amplifier for amplifying 10 and outputs a signal 212.
A drive circuit 213 drives the actuator 216 by the drive signal 214.

From the above adder 209 to the apex angle sensor 218
A closed loop is formed with the above configurations. In this configuration, control is performed so that the difference signal 210 is always zero, and as a result, the apex angle signal 219 acts so as to match the camera shake signal 204.

The light beam 222 whose incident angle is changed by the VAP 220 is transferred to the CCD 2 by the lens group 221.
The image is formed on the 23rd plane, and the image pickup signal 22 is obtained from the CCD 223.
4 is output.

For example, panning (hereinafter, also simply referred to as pan) or tilting (hereinafter, referred to as pan) of a camera equipped with the device.
When performing control at the time of (also simply referred to as tilt) or starting at the time of turning on the power, if the above basic control alone is used, an uncomfortable image will be captured.

Therefore, as described in JP-A-5-323436, a pan / tilt amount detecting means 230 and a frequency characteristic changing means 231 are provided, and the HPF 203 is referred to by referring to the values of the angular velocity signal 202 and the difference signal 210. And the frequency characteristics of the integration circuit 205 are changed in the non-vibration direction (the vibration isolation performance is deteriorated). Further, when returning, the frequency characteristics of the HPF 203 and the integration circuit 205 are changed in the vibration proof direction (the vibration proof performance is improved). That is, the frequency characteristic suitable for the amount of pan / tilt is realized.

With the above structure, a vibration damping effect can be obtained.

[0013]

However, the values of the angular velocity signal 202 and the differential signal 210 as described above are used as the pan / tilt amount, and the cutoff frequency of the HPF 203 or the frequency characteristic is changed to the LPF. In the method of sequentially performing, it is not possible to obtain a stable image because the frequency characteristics change rapidly. In particular, when the frequency characteristic is rapidly changed in the direction of increasing the image stabilization characteristic, a phenomenon called "swaying back" is likely to occur, which causes a problem that the photographer feels seasick.

(Object of the Invention) An object of the present invention is to provide an image blur preventing device which can always obtain a stable image.

[0015]

In order to achieve the above object, the present invention according to claims 1 to 5 comprises a correction amount changing means for changing the correction amount according to the output of the correction amount calculating means, and the correction amount. A time setting means for setting a time for operating the amount changing means is provided, and the time setting means increases the correction amount with respect to the time for decreasing the correction amount (deteriorating the image stabilizing characteristic) (improving the image stabilizing performance). ) The time is made long, that is, the time for returning from the panning or tilting state to the normal image stabilizing state is made long, and the correction amount is changed based on the set time.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a block diagram showing the arrangement of an image blur prevention apparatus according to the first embodiment of the present invention. The description will proceed assuming that the apparatus is installed in an image pickup apparatus.

Since the image stabilization is performed horizontally (YAW) and vertically (PITCH) independently, two systems are shown (solid line and dotted line) in the figure, but since these have the same function,
Similar to the conventional example, only one control will be described.

Reference numeral 101 denotes a gyro (angular velocity sensor), which outputs the shake angular velocity of the image pickup device. 102 is A / D
The converter converts the analog angular velocity signal into a digital angular velocity signal, and outputs the digital angular velocity signal to the system controller 130 operating at the sampling cycle T.

Reference numeral 107 is an actuator (stepping motor) for driving the VAP (correction means) 120, and 106 is a motor driver for supplying a current to the actuator 107. System controller 1
Reference numeral 30 compares the output of the amplifier 105 with the current position of the VAP 120, calculates in which direction and at what speed the VAP 120 is moved, and instructs the motor driver 106. Reference numeral 108 denotes a photo interrupter for detecting the parallel position of the VAP 120, which is a system controller 1
The state is input to the center position control means 109, which will be described later, in the unit 30.

The system controller 130 has the following HPF (high frequency pass filter) 103, LPF (low frequency pass filter) 104, amplifier 105, center position control means 109, time setting means 110, return time setting means 111, and , A filter constant switching means 112.

The HPF 103 is for cutting frequencies lower than the camera shake frequency. The LPF 10
Reference numeral 4 is for converting an angular velocity signal into an angular displacement signal, and is composed of a known digital filter. The amplifier 105 is for matching the angular displacement signal and the refraction amount of the light beam generated by the VAP 120. The HPF 103
The LPF 104 serves as a correction amount calculation means. The center position control means 109 is for issuing a command to the motor driver 106, which will be described later, so that the VAP 120 always comes to a predetermined center position when the image stabilization is started by the present system.

The time setting means 110 is the amplifier 10
The output of 5 (target position signal) is input (distance from the center position), and the output of the means is a correction amount changing means (return time determining means 111 and filter constant switching means 112). 2 which shows the operation time of the above and the input / output relationship here is shown in FIG.

The return time determining means 111 has a two-input comparator, one input terminal of which outputs the output signal of the time setting means 110, and the other input terminal of which outputs the timer, that is, "recovery". Output value of time determination means 111-
The value "1" is input, and the larger one is output.

The filter constant switching means 112 receives the output of the recovery time determining means 111 and receives the HPF 103 and L.
The constant of the PF 104 is changed, and the input / output relationship is shown in FIG. 3 described later.

FIG. 2 is a diagram showing the input / output relation of the time setting means 110 for setting the operation time of the correction amount changing means composed of the recovery time determining means 111 and the filter constant switching means 112, and the vertical axis indicates the operating time. And VAP on the horizontal axis
The optical axis angle is proportional to the apex angle of 120.

As can be seen from FIG. 2, the operating time is set longer as the target position goes to the end. This means that the pan / tilt amount increases toward the end, and therefore the correction amount is changed significantly over time.

◯ is a mark that does not include the value, and ● is a mark that includes it. Therefore, for example, when the optical axis angle is “0.48”, “0.5 sec” corresponding to the position of ● is the operation time. If it is set and the optical axis angle is "0.60", "1.5 sec" corresponding to the position of ● is set as the operation time.

FIG. 3 is a diagram showing the input / output relationship of the filter constant switching means 112, in which the vertical axis represents the cutoff frequency of the HPF 103, and the horizontal axis represents the pan / tilt state to the normal image stabilization state. I'm taking recovery time.

In the example of FIG. 3, when the return time is determined, H
The value of the cutoff frequency of the PF 103 changes, and the longer the correction amount changing time, the higher the time constant is set.

In FIG. 3 as well, ◯ indicates a mark that does not include the value, and ● indicates a mark that includes the value.
When set to "sec", the cutoff frequency of the HPF103 is set to "0.4 Hz" corresponding to the position of ●, and when the recovery time is set to "4 sec", the HPF103 is
The cutoff frequency of is 1.2 Hz, which corresponds to the position of ●.
Is set to

Next, the flow from the input signal will be specifically described.

FIG. 4 shows the signal waveform of each part.
FIG. 4A is an angular velocity signal output from the gyro 101, FIG.
(B) is a camera shake angular velocity signal output from the HPF 103,
4C shows an angular displacement signal output from the amplifier 105, FIG. 4D shows a pan / tilt amount signal output from the time setting means 110, and FIG. 4E shows an output from the recovery time determining means 111. A certain recovery time signal, FIG. 4 (f) is the HPF cutoff frequency value which is the output of the filter constant switching means 112.

First, the signal during normal image stabilization is relatively small and has a wide frequency band (0.5 to 15 Hz). In this case, since the angular displacement signal is in the vicinity of the center position, the output of the time setting means 110 is also "0" as shown in FIG. 4 (d). Therefore, the output of the filter constant switching means 112 has the lowest cutoff frequency of 0.1 Hz as shown in FIG. Anti-vibration in this case is most effective. This is because the HPF has a low cutoff frequency, so that it is converted into an angular displacement signal up to a low frequency to perform image stabilization.

Next, when panning is performed, the angular velocity signal [Fig. 4 (a)] outputs a constant value, and the angular displacement signal [Fig. 4 (c)] approaches the end accordingly. And At this time, the time setting means 110 sets the operating time one after another according to FIG. FIG. 4 (d) shows the pan / tilt amount signal at this time, and the recovery time setting means 111 compares this signal with the value of "recovery time before one sampling-1" and the larger one is selected. The output [see FIG. 4 (e)] is performed.

In FIG. 4 (e), T ₋ is the time until the correction amount is decreased (the anti-vibration performance is lowered), and this is the time until the angle of the VAP 120 is increased. Therefore, in the case where the correction angle such as pan / tilt is drastically changed, one sampling period T may be equal to T ₋ . Further, T ₊ is the time until the correction amount is increased (the image stabilization performance is deteriorated) (the time shown on the vertical axis in FIG. 2), and as is clear from FIG. 4 (e), “T ₋ <T ₊ The relationship will always be maintained.

The recovery time setting means 111 shown in FIG.
Filter constant switching means 112 for receiving an output as shown in FIG.
4 (f), the higher cutoff frequency component is cut, and the output of the amplifier 105 (FIG. 4 (c)) also returns to the vicinity of the center. At this time, the output of the time setting means 110 [FIG. 4 (d)] suddenly becomes a small value.
Since the value of "1" is larger, the output of the recovery time determining means 111 gradually becomes smaller, and the output of the filter constant switching means 112 [FIG. 4 (f)] is also one step at a predetermined time. The cutoff frequency will be lowered.

The pan / tilt control is performed by the above operation.

Although the present embodiment is expressed by open loop control,
The closed loop control is essentially the same as in the conventional example shown above.

(Second Embodiment) In the first embodiment,
Although it is realized digitally by using a microcomputer, the second embodiment of the present invention shows an example realized by an analog circuit.

FIG. 5 is a block diagram showing the arrangement of an image blur prevention device according to the second embodiment of the present invention.

In FIG. 5, 601 is a gyro,
Outputs the horizontal and vertical angular velocities of the imaging device. 602
Is an HPF, which is composed of a capacitor C, resistors R ₁ and R _2, and an analog switch, and is capable of varying frequency characteristics. Reference numeral 603 is an integrating circuit that converts the angular velocity signal into an angular displacement signal. Reference numeral 604 is an apex angle sensor for detecting the apex angle of the VAP 620. Reference numeral 605 denotes an adder that adds the outputs of the integration circuit 603 and the apex angle sensor 604 with opposite polarities and outputs the difference signal. 606
Is an amplifier that amplifies the difference signal and outputs it to the drive circuit 607. Reference numeral 608 denotes an actuator driven by the drive circuit 607, which allows the VAP 620 to operate.
Is controlled to the target angle.

An absolute value circuit 610 outputs the angular displacement signal as an absolute value. 611 is a peak hold circuit,
It is designed to output the maximum value of the input signals.
Reference numeral 612 denotes an LPF, which functions to attenuate the input signal with a predetermined time constant. 613 is a sawtooth wave generation circuit. 61
Reference numeral 4 denotes a comparator which converts the output of the LPF 612 into a duty ratio by inputting the output of the LPF 612 to a non-inverting input terminal and the output of the sawtooth wave generating circuit 613 to an inverting input terminal. . The output of the comparator 614 is connected to the analog switch control signal of the HPF 602. Here, when the duty ratio, which is the output of the comparator 614, increases, the cutoff frequency of the HPF 602 increases, and the anti-vibration effect decreases. In other words, it is a pan / tilt countermeasure.

Explaining in correspondence with the first embodiment, the time setting means for detecting the pan / tilt amount is composed of an absolute value circuit 610 and a peak hold circuit 611. The recovery time setting means is composed of the LPF 612, and the recovery time is determined by the time constant of the LPF 612.
The filter constant switching means is the sawtooth wave generation circuit 613 and the comparator 6.
It is composed of 14.

Here, the meaning of the sawtooth wave in the sawtooth wave generation circuit 613 will be described.

The frequency influences the roughness and smoothness of switching of the HPF 602, and the higher the frequency, the better. The vertical axis of the sawtooth wave is in proportion to the angle of the VAP 620, and the HPF 602 is switched at the angle of the minimum value and the maximum value. Further, since the shape of the sawtooth wave influences the HPF selection locus, it can be set to the most suitable shape.

(Third Embodiment) In the first and second embodiments, the optical VAP is used as the correcting means, but the correction is performed by moving the cutout range of the CCD which is the optical image plane. Electronic correction means is also possible. Therefore, in the third embodiment of the present invention, a case where an electronic correction means is used as the correction means will be described with reference to FIG.

In FIG. 6, reference numeral 710 is a lens group for connecting a subject to an image forming surface, and 711 is an image pickup device such as a CCD for converting optical information into electrical information, which is arranged at the image forming surface position. . Reference numeral 712 is a signal processing circuit for converting the output of the image pickup device 711 into a time series signal, and 713 is an A / D for converting an analog subject signal into a digital signal.
It is a converter. Reference numeral 714 is a field memory for storing an image signal for one screen, 715 is a field memory control circuit for controlling the field memory 714, and the field memory control circuit 715 controls the image data in the field memory 714. It is possible to output a part of. An image enlarging circuit 716 enlarges the image data partially extracted by the field memory control circuit 715 to the full angle of view. Thereafter, the signal is guided to an image recording system (not shown).

Reference numeral 720 is a time setting means, and the amplifier 70
The magnitude of the target position signal (distance from the center position), which is the output of No. 5, is input. This output is the operation time of the correction amount changing means.

Reference numeral 712 is a recovery time determining means, which has a two-input comparator, one input terminal of which receives the output signal of the time setting means 720, and the other input terminal of which is "recovery time determining means". The output value of 712-1 "is input, and the larger one is output. 72
2 receives the output of the recovery time setting means 721 and HPF 70
3 and filter constant switching means for changing the constant of the LPF 704. The contents of the correction amount changing means are as described in the first embodiment.

The output of the amplifier 705 (= the output of the correction amount calculation means) is input to the field memory control circuit 715, and an image corresponding to the correction amount is cut out and output one by one. Since this part is an already known example, its details are omitted.

According to each of the above-described embodiments, the processing is quickly performed in the direction of decreasing the correction amount (decreasing the vibration isolation performance) [FIG.
T in (e) _-], and increases the amount of correction (increase anti-vibration performance) and treated slowly in the direction [because it in the manner perform T _+] As to the time set in FIG. 4 (e), rapidly It is possible to obtain a stable image with respect to the changing correction amount.

(Modification) In the present invention, the vibration detecting means is not limited to a gyro (angular velocity sensor), but an angular acceleration sensor, an acceleration sensor, a velocity sensor, an angular displacement sensor, a displacement sensor, or an image shake itself is detected. Any method can be used as long as the shake can be detected.

In the present invention, a variable apex angle prism is taken as an example of the correction (optical) means, but a shift optical system for moving an optical member in a plane perpendicular to the optical axis or a plane vertical to the optical axis. It may be one that moves the shooting surface.

[0055]

As described above, according to the present invention,
With the time setting means, the time for increasing the correction amount (improving the image stabilization performance) is longer than the time for decreasing the correction amount (degrading the image stabilization characteristic), that is, from the panning or tilting state to the normal image stabilization state. The recovery time is lengthened and the correction amount is changed based on the set time.

Therefore, it is possible to always obtain a stable image even if the correction amount of the image shake obtained by the vibration detecting means changes rapidly.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining an operation time setting of a correction amount changing unit in FIG.

FIG. 3 is a diagram showing an input / output relationship of the filter constant switching means of FIG.

FIG. 4 is a diagram showing an output signal of each unit according to the first embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an image blur prevention device according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an image blur prevention device according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional image blur prevention device.

[Explanation of symbols]

 101,601 Gyro 103 HPF 104 LPF 105 Amplifier 107,608 Actuator 110 Time setting means 111 Recovery time setting means 112 Filter constant switching means 120,620 VAP 610 Absolute value circuit 611 Peak hold circuit 612 LPF 613 Saw wave generator 701 Angular velocity sensor 703 HPF 704 LPF 715 Frame memory control circuit 716 Image enlarging circuit 720 Time setting means 722 Filter constant switching means

Claims (5)

[Claims] 1. A vibration detecting means for detecting a vibration of an optical device, a correction amount calculating means for calculating a correction amount of an image shake caused by the vibration according to an output of the vibration detecting means, and the correction amount calculating means. In an image blur prevention apparatus including a correction unit that corrects image blur in accordance with the output of the correction amount changing unit that changes the correction amount according to the output of the correction amount calculating unit,
An image blur prevention device, comprising: time setting means for setting a time for operating the correction amount changing means. 2. The image blur prevention device according to claim 1, wherein the time setting unit is a unit that lengthens the time for increasing the correction amount with respect to the time for decreasing the correction amount. 3. The image blur prevention device according to claim 1, wherein the correction amount changing unit is a unit that changes the correction amount based on the time set by the time setting unit. 4. The image blur prevention device according to claim 1, wherein the vibration detection unit is an angular velocity sensor. 5. The image blur prevention device according to claim 1, wherein the correction amount calculation means is composed of a variable frequency high-frequency pass filter and a low-frequency band-pass filter.