JPH10150596A - Video camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a camera-shake correction residual component due to temperature fluctuation or a change with respect to passage of time in a camera- shake sensor. SOLUTION: The camera is made up of a camera-shake correction signal generating means 40, receiving sensing output from a camera-shake sensor 18 fitted to a camera main body, a camera-shake correction means 22 receiving the camera-shake correction signal, a calibration signal generating means 36 receiving biaxial shake signals Sx, Sy obtained by picking up an image of a test pattern 24, a gain adjustment means 38 that adjusts a gain of the sensing output based on a calibration signal Sc. The gain of the gain adjustment means is adjusted based on the calibration signal Sc, so that the biaxial signals obtained by picking up the image of the test pattern 24 approaches unlimitedly zero. Since the biaxial signal component includes a fluctuation component of a sensing output due to a temperature fluctuation or a with respect to passage of time change in the camera-shake sensor, the camera-shake correction residual component due to the fluctuation component of the sensing output due to the temperature fluctuation or the with respect to passage of time change in the camera-shake sensor is reduced through the calibration processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera equipped with a camera shake correction function suitable for a business video camera or the like. Specifically, by correcting the detection output from the camera shake sensor based on a calibration signal (calibration signal) obtained when a specific image is taken before imaging, camera shake correction due to temperature fluctuation or aging of the camera shake sensor is performed. Is intended to reduce the residual components of as much as possible.

[0002]

2. Description of the Related Art Video cameras equipped with a camera shake correction function are known. FIG. 5 shows a video camera 1 showing an example thereof.
0, a subject image is an image sensor via an optical system 12.
And an imaging signal is obtained. The imaging signal is converted into a video signal in the processor 16 for signal processing.

A camera shake sensor 18 is mounted on the camera body, and a shake detection output obtained from the camera shake sensor 18 is supplied to a camera shake correction signal generator 20 to generate a predetermined camera shake correction signal. 22. This loop changes the optical axis of the camera shake correction unit 22 so that a stable image can be obtained even if camera shake occurs.

[0004]

By the way, in the above-described camera shake correction system, the camera shake correction signal is adjusted at the factory shipment stage so that the screen shake due to the camera shake stops (becomes zero). However, it is not known under what environmental conditions the video camera is used. Sometimes used in extremely hot or cold places.

Since the detection characteristics of the camera shake sensor 18 provided in the camera shake correction system change due to changes in the environmental temperature and aging, the value of the detection output differs even for the same camera shake amount. There are cases. As a result, a correction error occurs, so that a residual component due to camera shake correction corresponding to the error must be necessarily allowed. This is because the camera shake correction system is an open loop. Although this residual component also occurs due to fluctuations in circuit constants other than the camera shake sensor 18, it is assumed that these components are handled in the following.

When the image stabilizing device is used for business use, the amount of residual components caused by fluctuations in the detection characteristics of the image stabilizing sensor 18 exceeds the allowable range of the image stabilizing operation because the image stabilizing operation of the image stabilizing sensor 18 is small. There is a risk. In particular, when the image stabilizing device adjusted in the manufacturing and service lines at normal temperature as described above is used in an extremely cold or extremely hot area, it is highly possible that the image stabilizing device exceeds the allowable range of the image stabilizing. This cannot satisfy the demand for business use.

Therefore, the present invention solves such a conventional problem. By adding a calibration function, it is possible to prevent the accuracy of camera shake correction from being lowered even by the use temperature or the secular change of the camera shake sensor. Calibration is performed so that residual components of camera shake can be reduced as much as possible.

[0008]

In order to solve the above-mentioned problems, a video camera according to the present invention comprises a camera shake correction signal generating means to which a detection output from a camera shake sensor attached to a camera body is supplied, and a camera shake correction signal generating means. A shake correction unit to which a correction signal is supplied, a calibration signal generation unit to which a two-axis shake detection signal obtained when a test pattern is photographed is supplied, and a gain of the detection output is adjusted based on the calibration signal. The gain of the gain adjustment unit is adjusted based on the calibration signal so that the two-axis shake signal obtained when the test pattern is photographed before imaging is a specified value. It is characterized by having been made.

In the present invention, the test pattern is imaged in a state where the test pattern is vibrated before the image is picked up.
At the same time, activate the image stabilization function. A calibration signal (calibration signal) is generated from a two-axis shake detection signal (horizontal and vertical shake detection signals) obtained when the camera shake correction function is operated. The gain of the detection output from the camera shake sensor is adjusted by the calibration signal so that the level of the two-axis shake detection signal is minimized.

The generation of the calibration signal is obtained in a state where the camera shake correction function is operated, and is generated in an environment where the video camera is used. Therefore, the calibration signal takes into account the ambient temperature and the secular change of the camera shake sensor. In this state, a calibration signal is obtained. Then, the gain of the gain adjustment amplifier to which the detection output from the camera shake sensor is supplied is adjusted so that the calibration signal becomes a specified value (the final target value is zero).

When the calibration signal becomes a minimum value, for example, zero, it means that the camera shake correction is functioning properly. The gain adjustment signal is used as an amplifier gain adjustment signal for correcting camera shake during actual imaging.

[0012]

Next, an embodiment of a video camera equipped with a camera shake correction function according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a specific example of a main part of a video camera 10 showing an example thereof. An image of a subject is formed on a CCD two-dimensional sensor 14 which is an image pickup device via an optical system 12 as in the prior art. Thus, an imaging signal is obtained. The imaging signal is converted into a video signal in the processor 16 for signal processing.

A camera shake sensor 18 is attached to the camera body. A gyro sensor, an acceleration sensor, a rotational angular velocity sensor, or the like can be used as the camera shake sensor 18.

A shake detection output So obtained from the shake sensor 18 (output separately for the X-axis component and the Y-axis component) So is a camera shake correction signal generating means 4 functioning as a target value calculating means.
0, a predetermined camera shake correction signal is generated, and the camera shake correction signal is supplied to the camera shake correction unit 22. The target value in the generation unit 40 is calculated by the camera shake correction signal so that the movement of the screen due to the camera shake becomes zero.

The camera shake correcting means 22 includes a variable apex angle prism which changes the optical axis by adjusting the angle of a lens having a liquid sealed therein, or a pair of purely cylindrical lenses (or spherical lenses). Are arranged so as to be freely rotatable, a cylindrical surface is rotated by a predetermined amount according to the amount of camera shake, and a vertex angle variable prism that adjusts the optical axis by changing the vertex angle of the prism is used. be able to.

In the present invention, a calibration process is performed on the detection output of the camera shake sensor 18 using a specific test pattern before imaging. This is because, as described above, the level of the detection output of the camera shake sensor 18 is different from the initial value because the detection characteristic thereof changes due to a temperature change or an aging change.

For this purpose, as shown in FIG. 1, a part of the video signal from the processor 16 for performing the signal processing is supplied to the two-axis shake signal detecting means 32 and 34. In this example, an X axis and a Y axis are used as two axes. Since the X-axis corresponds to the horizontal scanning direction and the Y-axis corresponds to the vertical scanning direction, the X-axis shake signal Sx is detected using the information of the horizontal scanning line of the video signal. Similarly, a Y-axis shake signal Sy is detected using information on a vertical scanning line of the video signal. The details will be described later.

The pair of shake detection signals Sx and Sy are supplied to the calibration signal generation means 36. The calibration signal Sc is used as a gain adjustment signal for adjusting a gain of a detection output from a camera shake sensor 18 described later. That is, when the image is taken while the test pattern 24 is vibrated while the camera shake correction function is activated, the pair of shake detection signals Sx and Sy are set to the target specified values (values as close as possible to zero, ideally zero). A calibration signal Sc for gain adjustment is generated from the shake detection signals Sx and Sy so as to obtain such a shake correction signal.

Therefore, in this embodiment, a gain adjusting means (amplifier) 38 for the detection output So is provided between the camera shake correcting means 40 and the camera shake sensor 18, and the output gain is adjusted by the calibration signal Sc. That is, the gain of the gain adjustment amplifier 38 is controlled by the calibration signal Sc so that a shake correction signal in which the pair of shake detection signals Sx and Sy approaches zero as much as possible is obtained.

The gain adjusting means 38 is also provided with two gain amplifiers for the X-axis component and the Y-axis component, but they are omitted in the figure. Therefore, the calibration signal Sc itself is also composed of two signals for gain adjustment for the X-axis component and gain adjustment for the Y-axis component.

The calibration is performed before the image is actually taken, and the calibration signal generation process is not performed during the image taking. Therefore, the calibration signal generation means 36 is provided with a memory means 42, in which the calibration signal Sc obtained before the imaging is stored, and the gain is controlled based on the stored calibration signal Sc during the imaging. Will be.

The calibration signal generating means 36 comprises a control unit (CPU) for performing processing for generating a calibration signal. The generating means 36 is provided with a calibration switch 44, and the switch 44 is turned on. Calibration signal Sc only when
Is generated and stored. The switch 44 is provided on the camera body.

FIG. 2 shows an example of a test pattern 24 for calibration processing which can be used in the present invention. In this example, a test pattern of a black cross on a white background is used. The position of the black cross and the thickness of the line are arbitrary, but in this example, the center of the cross is selected as the center of the white background, and the thickness of the line is selected to be several lines (for example, two lines). Have been.

When performing calibration, the test pattern 24 is placed on the front surface of the optical system 12 so as to fill the angle of view. When the test pattern 24 is forgotten, a simple test pattern created using drawing paper or a notebook can be used.

Then, an appropriate vibration is applied to the test pattern 24. In addition, the camera shake correction function is set to the operating state. In this state, the test pattern 24 is imaged.

Then, the video signal Sv from the processor 16 is obtained as a signal as shown in FIGS. This signal is a signal after camera shake correction. FIG. 3 shows an x-th line obtained from the X-axis shake detecting means 32 (see FIG. 2).
Video signal Sx. Therefore, the X-axis shake detection means 32 outputs a video signal Sx of only x lines as a camera shake detection signal. Of course, the calibration signal generating means 36 may extract only the x-line signal. The video signal Sx is composed of a luminance signal Sa corresponding to a white background of the test pattern 24 and a luminance signal Sb corresponding to a black cross line.

Assuming that the time until the luminance signal Sb is obtained from the horizontal synchronization signal PH is Th, if there is camera shake,
The signal position (time) of the luminance signal Sb is shifted by ΔT by the amount corresponding to the camera shake. The calibration signal generating means 36 uses the image signal Sx in a camera shake state,
The calibration signal Sc is generated based on the calibration control program so as to obtain a camera shake correction signal (X-axis camera shake correction signal) in which the camera shake ΔT becomes infinitely zero.

Similarly, the video signal near the horizontal cross in FIG.
It is detected by the shaft runout detecting means 34. This video signal Sy, which is a camera shake detection signal, is just n, as shown in FIG. 4B.
Since the line and the (n + 1) th line correspond to a horizontal cross, the luminance signal is obtained as a black level. The camera shake on the Y axis is determined by whether or not the line from which the black level video signal is obtained falls on the nth line with reference to the vertical synchronization signal (A in the figure). The deviation ΔV from the n-th line is a camera shake component in the Y-axis direction.

For this reason, this video signal Sy is supplied to the calibration signal generating means 36, and the camera shake correction such that the camera shake ΔV becomes infinitely zero based on the built-in calibration control program as described above. Signal (Y-axis image stabilization signal)
A calibration signal Sc for Y-axis correction is generated.

The gain of the corresponding gain adjusting means 38 is controlled by the calibration signal Sc. The video signals Sx and Sy are obtained in a state where the camera shake correction function is activated. Therefore, since it is obtained as a video signal taking into account the fluctuation of the detection output So due to the temperature fluctuation and the secular change of the camera shake sensor 18, the camera shake amount △
If H and ΔV are close to zero, the residual component (error component) of the camera shake correction due to temperature fluctuation and aging can be greatly reduced even if the camera shake correction system is open-loop control.

Since the calibration signal Sc is stored in the memory means 42, when the video camera 10 is used under similar environmental conditions or when the calibration operation performed immediately before has not been performed, much time has not elapsed. In such a case, the calibration signal Sc stored in the memory means 42 can be directly used without performing the calibration process again.

The test pattern 24 shown in FIG. 2 is merely an example, and other test patterns can be used. The timing of acquiring the video signals Sx and Sy is the same, and the example in the figure is an example.

[0034]

As described above, in the video camera according to the present invention, the calibration process is performed while the camera shake correction function is activated, and the gain for the camera shake sensor detection output is adjusted by the calibration signal obtained at that time. (Calibration).

According to this, even when the detection characteristic of the camera shake sensor changes due to aging or the like, or when the detection characteristic changes due to use in a temperature environment other than room temperature, the calibration can be performed. By performing the image processing, the residual component of camera shake correction due to the fluctuation of the detection characteristic can be significantly reduced. As a result, even if the video camera is a professional video camera that has less shaking in a normal use state, there is no possibility that the shake correction residual component exceeds the allowable range.

The means required for the calibration process are as follows:
Since it is very inexpensive and small, it can be applied not only to professional video cameras, but also to consumer video cameras having a camera shake correction function.

The calibration operation is a very simple operation because it only takes a test pattern.
The time for the calibration operation can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of a main part showing an embodiment of a video camera according to the present invention.

FIG. 2 is a plan view showing an example of a test pattern.

FIG. 3 is a waveform diagram of an X-axis shake detection video signal.

FIG. 4 is a waveform diagram of a Y-axis shake detection video signal.

FIG. 5 is a system diagram of a conventional video camera.

[Explanation of symbols]

10 video camera, 14 imaging means, 32
..X-axis shake detection means, 34 ... Y-axis shake detection means,
36 ... Calibration signal generation means, 38 ...
.Gain adjustment means, 18: hand shake sensor, 22
.Camera shake correction means, 40... Target value calculation means

Claims (3)

[Claims] 1. A camera shake correction signal generating unit to which a detection output from a camera shake sensor attached to a camera body is supplied, a camera shake correction unit to which the camera shake correction signal is supplied, and a test pattern obtained when a test pattern is photographed. A calibration signal generation unit to which a two-axis shake detection signal is supplied; and a gain adjustment unit to adjust a gain of the detection output based on the calibration signal, wherein the test pattern is taken before imaging. 2 obtained
A video camera, wherein the gain of the gain adjusting means is adjusted based on the calibration signal so that the shaft shake detection signal becomes a specified value. 2. The video camera according to claim 1, further comprising a two-axis shake detection unit for the X-axis and the Y-axis to which the imaging signal is supplied, provided at a stage preceding the calibration signal generation unit. 3. The calibration signal generation means includes a memory means, in which a gain adjustment signal based on the two-axis shake detection signal is stored, and the two-axis shake detection signal is stored during imaging. 2. The video camera according to claim 1, wherein the video camera is supplied to a gain adjusting unit.