JP3437339B2 - Image stabilizer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a shake correction device used for shake correction of a camera, a video camera, and the like. 2. Description of the Related Art Conventionally, in the field of photographing equipment such as a camera and a video camera, automation and multi-functions have been achieved in all aspects such as exposure setting and focus adjustment, so that good photographing can be easily performed. It is becoming. In recent years, a shake correction device for correcting camera shake has been put to practical use. Particularly in small-sized video cameras and the like, the use of a recent high-magnification lens causes noticeable camera shake on the telephoto side and significantly lowers the image quality. Therefore, the shake correction device has become an essential function. . FIG. 5 is a block diagram showing a conventional shake correcting apparatus. An optical system as an example using an angular velocity sensor such as a vibrating gyroscope as a shake detecting means and a variable apex prism (VAP) as an image correcting means. FIG. In FIG. 5, reference numeral 501 denotes a vibration gyro, which is attached to a photographing device such as a camera or a video camera, and outputs a signal corresponding to the shake when the shake occurs. Reference numeral 502 denotes a DC cut filter that allows only the AC component of the signal output from the vibration gyro 501 to pass, and reference numeral 503 denotes an amplifier that amplifies the AC component signal. A microcomputer 515 processes the amplified signal. Reference numeral 510 denotes a VAP for optically detecting shaking of an image to be picked up; 511, a sensor for converting the optical output of the VAP 510 into an electric signal; 512, an amplifier for amplifying the electric signal and inputting it to a microcomputer 515; The VAP 510 according to a control signal output from the microcomputer 515
Is a driving circuit for driving the. In the microcomputer 515, 504 is an A / D converter for converting the output of the amplifier 503 to a digital signal, 513 is an A / D converter for converting the output of the amplifier 512 to a digital signal, and 505 is a signal from the A / D converter 504. A high-pass filter for passing the high-frequency component of the digital signal; 506, a correction circuit for correcting the phase and gain of the high-frequency component; 507, an integrator for integrating the corrected signal; 508, the integrated output and A / D converter 5
An adder 509 for adding the digital signal from T.13,
Is a D / A converter that converts the added output into an analog signal and outputs it as a control signal. Next, the operation will be described. A signal obtained by detecting the vibration of the imaging device detected by the vibration gyro 501 is DC-cut by the filter 502, amplified by the amplifier 503, and input to the microcomputer 515. Microcomputer 515
A / D converter 504, high-pass filter 5
05, the correction circuit 506, and the integrator 507, the target value for driving the VAP 510 is calculated. On the other hand, the movement of the VAP 510 is
After being detected by the amplifier 512 and amplified by the amplifier 512,
15 is input. Then, the signal passes through the A / D converter 513 and is added to the target value by the adder 508 as a feedback signal, whereby the actual correction amount is calculated. The calculated correction amount is passed as a control signal from the microcomputer 515 through the D / A converter 509 to the drive circuit 514.
, And the drive circuit 514 outputs V in accordance with the control signal.
The AP 510 is driven. With the above operation, the VAP control is performed. However, in a device such as a video camera that uses a battery or the like as a power supply, an inhibit voltage is provided in accordance with the capacity of the battery, and the power supply voltage falls below the inhibit voltage. In the case of the above-described conventional shake correction apparatus, when the capacity or voltage of a battery such as a camera battery decreases, the power supply voltage fluctuates in accordance with the movement of the VAP 510. As a result, the vibration gyro 501
Output itself slightly fluctuates. As a result, the minute fluctuation is erroneously determined to be camera vibration, and instead of suppressing the vibration near the prohibition voltage, the VAP 510 malfunctions or becomes uncontrollable and the image is more disturbed than the camera shake. There was a problem. As a countermeasure against this, if the prohibition voltage is increased, there is a problem that the replacement of the battery is expedited. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vibration correcting device which can prevent malfunction or loss of control when a power supply is in a reduced power state. According to the first aspect of the present invention, there is provided a first detecting means for detecting a vibration of an image pickup means, a correcting means for correcting a shake of an image picked up by the image pickup means,
Filtering means for filtering the output of the first detecting means, changing means for changing the filter characteristics of the filtering means, and controlling the correcting means based on the output of the filtering means in a direction for correcting the image fluctuation. Control means for detecting the power reduction state of the power supply, and second detection means for controlling the change means based on the detection output. According to the first aspect of the present invention, when the second detecting means detects a power reduction state of the power supply, a filter through which the detection output of the first detecting means passes by the detection output. Since the filter characteristic of the means is changed, it is possible to prevent the correction means from inadvertently malfunctioning or becoming uncontrollable. FIG. 1 is a block diagram showing a configuration of a shake correction apparatus according to a first embodiment of the present invention.
In the figure, reference numeral 101 denotes a power reduction state detection device as second detection means for detecting a power reduction state of a power supply, and 102 denotes ON / O of an image stabilization control state based on a detection signal of the power reduction detection device 101
This is a switch for switching the FF. Note that the vibrating gyroscope 501 constitutes first detection means, the VAP 510 and the sensor 511 constitute correction means, and the microcomputer 515 constitutes control means. Further, for the other portions, the portions corresponding to those in FIG. 5 are denoted by the same reference numerals, and redundant description will be omitted. Next, the operation will be described with reference to the flowchart of FIG. In step S201, the microcomputer 51
The gyro output signal input to 5 is fetched. In step S202, filtering for removing DC components, phase compensation, and the like of the signal captured in step S201 is performed. In step S203, a frequency and an amplitude necessary for controlling the VAP 510 are calculated from the filtered signal. Step S204
In, the output of the power reduction detection device 101 is monitored to determine whether or not the power supply is in the power reduction state. If it is determined that the power is not in the reduced power state, the process proceeds to step S207, and a target value for driving the VAP 510 is calculated from the frequency and amplitude previously calculated, and the voltage is set. If a power reduction state is detected in step S204, step S204
Proceeding to 205, the switch 102 is turned off. Thereafter, in step S206, a predetermined reference voltage is set as a control signal. This reference voltage is VAP510
Is the voltage required to keep the balance in a balanced state. Next, in step S208, the actual drive amount is calculated from the voltage set in step S207 or step S206 and the output of the sensor 511.
In step S209, a control signal is output to the drive circuit 514, for example, as a PWM output according to the drive amount. As a result, the VAP control is performed. However, if the reference voltage is set in step S206 after the detection of the power reduction, the VAP 510 transitions to an equilibrium state in step S208, and finally stops. As a result, even when the gyro output signal fluctuates due to driving of the VAP 510 during power reduction, it is possible to suppress the VAP 510 from inadvertently moving due to the fluctuation. When the VAP control is stopped as described above, for example, in the case of a video camera, the information display in the finder displays a warning of power reduction and a display such as image stabilization OFF, so that the photographer can be notified. The user can be notified of the OFF state to call attention. The switch 102 may be provided at a location other than that shown in FIG.
This switch 102 may be provided anywhere as long as the image shake correction by the image 11 can be substantially stopped. FIG. 3 is a block diagram showing the configuration of a shake correction apparatus according to a second embodiment of the present invention. In FIG. 3, parts corresponding to those in FIGS. 1 and 5 are denoted by the same reference numerals. Reference numeral 301 denotes a high-pass filter 50 configured in the microcomputer 515 according to a detection signal of the power reduction detection device 101.
5. Filter characteristic changing means for changing the filter characteristic of the filter means by the correction circuit 506 and the integrator 507. Next, the operation will be described with reference to the flowchart of FIG. In step S401, the microcomputer 51
The gyro output signal input to 5 is fetched. In step S402, the power reduction state detected by the power reduction detection device 101 is checked. If the power reduction state is detected, the process proceeds to step S403, and if not, the process proceeds to step S404. If a power reduction is detected, step S40
At 3, the filter characteristics of the filter means are changed. In this case, it is known empirically that a low-frequency signal is generated with respect to the voltage fluctuation at the time of power reduction. However, in step S403, based on the empirical fact, the pass band of the signal is set to the high frequency side. I'm shifting to However, this shift amount is also an amount determined based on experience. Next, in step S404, the signal is actually filtered, and then in step S405, the frequency and amplitude are calculated. Here, when the power reduction is detected, as described above, the filter characteristic is shifted to a higher frequency range. Therefore, in the calculation in step S405, a result that is not affected by the voltage fluctuation occurring at the time of the power reduction is obtained. Become. From the result obtained in step S405, the drive amount of VAP 510 is calculated in step S406, and output to actual drive circuit 514 in step S407. As a result of this operation, the anti-vibration performance is slightly reduced, but the photographer can be alerted by a warning display of power reduction or the like as in the first embodiment. As described above, by detecting the power reduction state and changing the cutoff frequency of the filter in accordance with the state to limit the signal components, the inadvertent movement of the VAP 510 can be suppressed. For this reason, it is possible to perform a somewhat favorable anti-vibration control even in the reduced power state. Further, by suppressing inadvertent behavior near the power reduction, the shut-off voltage can be reduced. As described above, according to the present invention,
By monitoring the state of power reduction and stopping the operation of image shake correction near the power reduction or changing the characteristics of the filter, malfunction or loss of control causes image blur It is possible to prevent further disturbance. Furthermore, even in the case of power reduction, a more stable operation than before can be performed, so that the forbidden voltage can be reduced. Therefore, in a video camera or the like,
The recording time by the battery can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is a flowchart showing an operation of the first embodiment. FIG. 3 is a block diagram showing a second embodiment of the present invention. FIG. 4 is a flowchart showing the operation of the second embodiment. FIG. 5 is a block diagram showing a conventional shake correction device. DESCRIPTION OF SYMBOLS 101 Low-power detection device 102 Switch 301 Filter characteristic changing circuit 501 Vibrating gyro 505 High-pass filter 506 Correction circuit 507 Integrator 508 Adder 510 VAP 511 Sensor 515 Microcomputer

Claims (1)

(57) [Claim 1] First detecting means for detecting a vibration of an imaging means, correcting means for correcting a shaking of an image picked up by the imaging means, and first detecting means Filter means for filtering the output of the filter means, changing means for changing the filter characteristics of the filter means, control means for controlling the correction means in a direction for correcting the image shaking based on the output of the filter means, And a second detecting means for controlling the change means based on the detected output.