JPH0946575A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct hand-shake of a television camera effectively for the full focus range of an image pickup lens. SOLUTION: The image pickup device using an optical system 2 incorporating an image pickup device lens whose focus is variable and CCDs 4R, 4G, 4B as image pickup elements, an X axis shake detector 7 and a Y axis shake detector 8 detecting a shake in a horizontal and vertical direction in a plane perpendicular to an image pickup optical axis, an optical axis angle variable optical section 1 controlling an incident optical angle of a light incident to the optical system 2, a 1st deflection correction means varying a read image frame of image pickup information from the CCDs 4R, 4G, 4B depending on an amount of a shake of the image pickup device by the shake detection means, and a 2nd shake correction means controlling the optical angle of a light incident to the optical system 2 by the optical axis angle variable optical section 1, and also a function that uses a CPU 20 to select automatically the correction means and uses a correction device selector switch 10 to select the correction means in use manually.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus having a photographing optical system having a variable focal length and a CCD image pickup element, and more particularly to an image pickup apparatus having a plurality of camera shake correction functions.

[0002]

2. Description of the Related Art Conventionally, in an image pickup device such as a television camera, a shake of a video image due to a shake has been a problem. In particular, in an image pickup apparatus having an image pickup optical system having a zoom function, it is difficult to effectively prevent the handshake over the entire focal length adjustment range because the characteristics of the handshake vary depending on the magnification of the optical system. It was

Now, a conventional camera shake correction mechanism will be described with reference to FIGS. 3 to 6. As a camera shake correction mechanism, a method of cutting out an image frame of an image pickup area of a CCD (hereinafter, simply referred to as “electronic type”) and a method of adjusting an optical axis angle of incident light by a prism or the like (hereinafter, simply referred to as “optical type”) In both cases, the camera shake is detected by the angular velocity sensor and the correction is performed according to the detected value.

First, the electronic type will be described with reference to FIG.
As shown in (a), the CCD 4 used electronically has a large area A0 whose image pickup area has more horizontal scanning lines than the video standard of the television. In an actual image, an area A1 having a horizontal scanning line conforming to the standard is cut out from the area A0 and used as an image signal. At this time, the area A1 is divided into, for example, the area A2 or the area A3 in accordance with the camera shake detection signal. As shown in the figure, within the area A0, the image is moved and cut out so that the image does not shake as a result, and the image shake due to camera shake is corrected.

FIG. 3B shows an electronically correctable angle, where the focal length of the imaging lens 15 is f,
Area A1 has a side of 2h0 and area A0 has a side of 2 (h + h
0) (both in the vertical direction), and the correctable angle θ at this time is as follows: tan (θ ₀ + θ) = (h + h ₀ ) / f (1) tan θ ₀ = h ₀ / f (2) θ ₀ Since + θ is small, θ ₀ + θ = (h + h ₀ ) / f (3) θ ₀ = h ₀ / f (4) is eventually satisfied, and therefore θ = h / f (5) and the maximum correction angle can be obtained.

If the CCD 4 is 2/3 inch,
The area A0 is 8.8 mm × 6.6 mm, and if the margin area for correction is approximately 30% in terms of the side ratio, then 2.
It is 64 mm x 1.98 mm. Therefore, the correction area on one side from the center is half, 1.32 mm × 0.9
It becomes 9 mm. At this time, the focal length of the imaging lens 15 is f = on the short focal length side (hereinafter, simply referred to as “wide side”).
In the case of 8 mm, the correction angle θ is 0.
A large value can be obtained with 99 ÷ 8≈0.124 rad≈7 degrees, but 0.99 ÷ 20 when f = 200 mm on the long focal length side (hereinafter simply referred to as "tele side").
It is an extremely small value of 0≈0.005 rad≈0.28 degrees.

Therefore, in the above-mentioned electronic system, as shown in FIG. 5, the wider the image pickup lens 15 is, the larger the angle at which the optical axis can be corrected becomes. On the contrary, on the tele side, this becomes a very small value. It was difficult to correct a large camera shake on the tele side.

The optical system will be described below. As shown in FIG. 4, a prism 16 having a variable apex angle is arranged in front of the image pickup lens 15 so that one surface thereof is perpendicular to the optical axis. There is. Here, the apex angle of the prism 16 is α,
Assuming that the deflection angle of emission is δ, the refractive index of the prism 16 is n.
Since sin θ = sin (α + δ) = nsinα (6) θ is small, θ = α + δ = nα (7), and therefore δ = (n−1) α (8). Here, when n = 1.5 and α is displaced by ± 2 degrees, the deflection angle δ can be changed by ± 1 degree.

The shake angle δ of ± 1 degree is a sufficient value for correcting a hand shake angle that actually occurs on the telephoto side, but when the focal length on the wide side is f = 8 mm, for example, the correction amount. Is 8 × tan1 °, which is only 0.
It is 14 mm, which is an extremely small value as compared with the above-mentioned electronic 0.99 mm.

Therefore, in the above-mentioned optical system, the image pickup lens 1
The optical axis correction angle by the prism 16 arranged at the front end of 5 is constant regardless of the focal length of the imaging lens 15, and the optical axis correction angle does not decrease even on the telephoto side as shown in FIG. Although it works effectively in severe telephoto, it has a drawback that it does not work effectively on the wide-angle side, especially for large translational shake which is a problem in close-up photography.

As described above, the characteristics of the electronic and optical correction mechanisms are constant in the optical system regardless of the focal length of the image pickup lens 15 from the viewpoint of the correction angle as shown in FIG. In the conventional example, the maximum is 1 degree on each side. On the other hand, in the electronic type, the correction angle increases as the focal length becomes shorter, and the electronic type and the optical type cross at approximately f = 50 mm, and it can be seen that the electronic type is advantageous at a shorter focal length.

On the other hand, from the viewpoint of the correction amount and the correction ratio, as shown in FIG. 6, in the optical system, the correction amount becomes larger as the focal length becomes longer, and when f = 140 mm, the correction amount is approximately 2.
The correction ratio is 5 mm, which is about 37%. On the other hand, in the electronic method, the correction amount is constant at a maximum of 0.99 mm on one side in the vertical direction, and therefore the correction ratio is also constant at approximately 15%.

[0013]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to effectively prevent image shake due to camera shake of an image pickup apparatus having a variable focal length optical means and a CCD image pickup element, regardless of the set value of the focal length. Is what you are trying to do.

[0014]

An image pickup apparatus including a photographing optical system having a variable focal length and a CCD image pickup element,
Detection means for detecting horizontal and vertical shakes in a plane perpendicular to the photographing optical axis, and control for controlling incident light angles incident on the photographing optical system in the horizontal and vertical directions in the plane perpendicular to the photographing optical axis. A first shake correction means for changing the reading of the image pickup information from the CCD in accordance with the detected amount of shake of the image pickup apparatus by the detection means, and a control means according to the detected amount of shake of the image pickup apparatus by the detection means. And a second shake correction unit that controls the angle of incident light incident on the photographing optical system.

Using only the first shake correction means,
Using only the second shake correcting means, using the first shake correcting means and the second shake correcting means at the same time,
Further, there is provided selection means for selecting not to use both the first shake correction means and the second shake correction means.

A means for detecting the focal length of the photographing optical system is provided, and the first shake correcting means or the second shake correcting means is automatically selected as the shake correcting means to be used according to the value of the focal length. The configuration.

A means for detecting the focal length of the photographing optical system is provided, and different weights are automatically assigned to the operations of the first shake correction means and the second shake correction means according to the value of the focal length. The configuration is

When the first shake correction means is not used, C
The above problem is solved by a configuration in which horizontal scanning lines are removed from all pixels of a CD at regular intervals to create a video image.

Therefore, it is equipped with a first shake correction means by an electric method which is advantageous on the wide side and a second shake correction means by an optical method which is advantageous on the tele side, and the focal length of the image pickup lens can be improved. Depending on the state, by manually or automatically selecting and using a shake correcting means to be used, or in combination, effective shake correction is performed on the wide side and the tele side.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.

The configuration of this embodiment is shown in a schematic block diagram in FIG. 1, in which an optical axis angle variable optical section 1 is provided adjacent to the front surface of an optical system 2. CCD as an image sensor
4R, 4G, and 4B are arranged at predetermined portions of the dichroic prism 3 to receive RGB signals as color components. The variable optical axis angle optical unit 1 is provided with a tilt angle detector 6 for detecting the optical axis angle, a drive mechanism 11 for adjusting the optical axis angle of the variable optical axis angle optical unit 1, and a control unit 21 and a drive. The optical axis angle is controlled by the circuit 22.

The optical system 2 is provided with a T / W switch 9 for operating the telephoto side and the wide side, an optical system position detector 12 for obtaining the focal length of the image pickup lens, and a device perpendicular to the photographing optical axis of the optical system 2. X to detect horizontal and vertical runouts in the plane
The shaft shake detector 7 and the Y-axis shake detector 8 are fixed to the image pickup apparatus, and the detection results of both are input to the CPU 20. Further, a correction mechanism selection switch 10 for selecting a correction mechanism is provided, and its output is also input to the CPU 20 to select a correction mechanism to be operated.

The drive timing generator 23 takes timings for driving the CCDs 4R, 4G, 4B based on the judgments made by the CPU 20 based on the information from the detectors. The CCD drive sections 5R, 5G, 5B, And a signal processing circuit below the correlated double sampling circuit (CDS) 24. Further, the video outputs of the CCDs 4R, 4G, 4B are output as video signals via the CDS 24, the A / D converter 25, the H late converter 26, the V late converter 27 and the video signal processing unit 28, respectively.

Next, the function of each block of this embodiment will be described. First, FIG. 2 is an optical block of a color separation and imaging unit of a three-plate color camera, in which incident light is red R, green G, and blue B by a three-color separation type dichroic prism 3.
The RGB light is decomposed into the three colors and travels in the respective directions. CCDs 4R, 4G, and 4B are fixed at the emission ends of the dichroic prism 3 for emitting RGB light so as to match the images. The CCD used here detects the brightness of each color image, and has a very large number of pixels, for example, the number of pixels is 1016 horizontal pixels and the number of scanning lines is 647. .

The CCD used here constitutes an electronic image stabilization mechanism as in the conventional example described with reference to FIG.
The CPU 20 judges the detection output of the shaft shake detector 8 and, according to the instruction, the image is not shaken from the image pickup area A0 of the CCD 4 to the actual image area A1 as shown in FIG. The image is sequentially cut out according to the amount of camera shake to correct the camera shake.

The optical system 2 includes an image pickup lens 15 having a variable focal length. For example, the focal length f is 8
There is a 15 × zoom of mm to 120 mm. The T / W switch 9 is for arbitrarily setting the focal length to the tele side or the wide side, and the set focal length is detected by the optical system position detector 12 and input to the CPU 20 according to the focal length. This is used to select an appropriate correction method.

The variable optical axis angle optical section 1 is installed in front of the optical system 2 so as to change the incident optical axis. The variable optical axis angle optical unit 1 in this embodiment is composed of a plano-convex and columnar optical member 1a and a plano-concave and columnar optical member 1b, and the convex portion and the concave portion have the same curvature. The concave portion and the concave portion are rotatably closely attached and held. The optical member having this configuration is provided in both the horizontal direction and the vertical direction in the plane perpendicular to the photographing optical axis to configure the optical axis angle variable optical unit 1.

The variable optical axis angle optical unit 1 is provided with a tilt angle detector 6 and a drive mechanism 11, and the drive mechanism 11 is fixed to a movable optical member 1a of the variable optical axis angle optical unit 1.
The prism apex angle is equivalently changed by rotating in the direction indicated by arrow Ra. The drive mechanism 11 is controlled by the CPU 20 based on the measurement value of the tilt angle of the optical member 1a with respect to the optical axis of the tilt angle detector 6 and the detection outputs of the X-axis shake detector 7 and the Y-axis shake detector 8. It is controlled via the unit 22 and the drive circuit 21. The process of changing the optical axis is the same as the angle change of the incident optical axis when the apex angle α is made variable in the conventional example described with reference to FIG. 4, and the description thereof is omitted.

As described above, the hand shake is caused by the X-axis shake detector 7
And the Y-axis shake detector 8, each of which is provided with an angular velocity sensor and an acceleration sensor in order to detect an angular displacement and a parallel displacement of the image pickup device.
The detection signals of the X-axis shake detector 7 and the Y-axis shake detector 8 are input to the CPU 20 to calculate the angular shake and the parallel movement amount, and further the information from the optical system position detector 12 is added to determine the correction amount. , Command to the electronic or optical correction mechanism.

Further, the correction mechanism selection switch 10 is for selecting the correction mechanism to be used. There are cases where the automatic selection by the CPU 20 has priority and cases where manual selection has priority, and manual selection. When priority is given to (1), settings can be made such that no correction mechanism is used, an electronic correction mechanism is used, an optical correction mechanism is used, and both correction mechanisms are used simultaneously.

For example, in the automatic correction operation by the CPU 20, the optical system position detector 12 measures the focal length of the image pickup lens 15 incorporated in the optical system 2, and the electronic correction mechanism and the optical type are measured according to the value of the focal length. It is determined which of the correction mechanisms is to be used preferentially, and the correction operation is performed by using another method as an auxiliary means.

In the configuration of the image pickup apparatus as described above, f = 5
With 0 mm as the branch point, the optical system is prioritized on the long focal length side, that is, the tele side to assist the electronic system, and conversely, the electronic system is prioritized on the short and long focal length side, that is, the wide side, and the optical system is set. It is to assist. In particular, since the shake of the parallel movement is large at the wide end, the signal from the acceleration sensor that automatically detects the parallel movement by the CPU 20 based on the information of the wide end is used as the shake signal, and the electronic correction is used, which is great in close-up photography. The effect can be obtained.

By using a combination of the above-mentioned optical system and electronic system, effective camera shake correction can be carried out at all focal lengths as shown in the characteristic of the composite correction of FIG.

Next, the processing of the video signal will be explained. The correlated double sampling circuit (CDS) 24 is a CCD.
The video signals output from 4R, 4G, and 4B are amplified with a specified gain, and then a correlated double sampling method is applied to convert them into red (R), green (G), and blue (B) color signals. The A / D converter 25 converts an analog color signal into a digital color signal and provides it for rate conversion processing.

The H rate converter 26 is formed of a memory circuit which stores digital color signals that are sequentially input and outputs the digital color signals at a specified timing, and switches the operation according to the setting of the correction mechanism. That is, when the electronic image stabilization mechanism is selected, the area A1 in the imaging area A0 shown in FIG.
The horizontal image frame corresponding to is cut out, and if the electronic image stabilization mechanism is not selected, the digital color signal is output as it is.

On the other hand, the V rate converter 27 is formed of a memory circuit which stores digital color signals which are sequentially input and outputs the digital color signals at a specified timing, and switches the operation according to the setting of the correction mechanism. That is, when the electronic image stabilization mechanism is selected, the vertical image frame corresponding to the area A1 in the imaging area A0 shown in FIG. 3A is cut out, and when the electronic image stabilization mechanism is not selected, the vertical image frame is left unchanged. The digital color signal of is output.

Therefore, the functions of the H rate converter 26 and the V rate converter 27 realize an electronic camera shake correction mechanism instructed by the CPU 20, and obtain an image signal of a high pixel when the electronic camera shake correction mechanism is not used. You can

Next, the video signal processing unit 28 performs signal processing such as gamma correction required for a normal television camera on each digital color signal, and then converts it into a luminance signal and a color difference signal, and further, a video signal. Converted to and output.

The hand shake detection is not limited to the angular velocity sensor and the acceleration sensor, and may be obtained by comparing the image with the previous frame. Further, it is needless to say that the present invention is not limited to the CCD three-plate type of the present embodiment, and may be a single-plate type, two-plate type, four-plate type, or the like.

[0040]

EFFECTS OF THE INVENTION An electronic image stabilization mechanism, which is advantageous on the wide side, and an optical image stabilization mechanism, which is advantageous on the telephoto side, are combined, and camera shake compensation is performed according to the focal length of the image pickup lens, so there is no shaking at all focal lengths. A high quality image can be obtained.

When the electronic type is not used, the CCD
Since horizontal lines are thinned out at equal intervals from all the pixels to generate a video signal, an image with high resolution can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an image pickup apparatus including an image stabilization mechanism according to the present invention.

[FIG. 2] RGB by a dichroic prism of an imaging unit
The structure of a separation optical system and CCD is shown.

FIG. 3 is a diagram for explaining an electronic image stabilization mechanism, in which (a) shows an image cutting frame on a CCD,
(B) shows the calculation of the correction angle of the optical axis corresponding to the image cutout frame.

FIG. 4 is a diagram for explaining an optical image stabilization mechanism.

FIG. 5 is a diagram showing a relationship between a focal length of an imaging lens and a camera shake correction angle.

FIG. 6 is a diagram showing a relationship between a focal length of an imaging lens, a camera shake correction ratio, and a correction amount.

[Explanation of symbols]

 1 Optical axis angle variable optical section 2 Optical system 3 Dichroic prism 4, 4R, 4G, 4B CCD 5R, 5G, 5B CCD drive section 6 Tilt angle detector 7 X axis shake detector 8 Y axis shake detector 9 T / W switch 10 correction mechanism selection switch 11 drive mechanism 12 optical system position detector 15 imaging lens 16 prism 20 CPU 21 control unit 22 drive circuit 23 drive timing generator 24 CDS 25 A / D converter 26 H late converter 27 V late converter 28 video Signal processor

Claims (5)

[Claims] 1. A photographing optical system having a variable focal length and a CC.
An image pickup apparatus including a D image pickup device, wherein the image pickup apparatus includes a detection unit that detects shakes in two directions, which are perpendicular to each other in a horizontal direction and a vertical direction in a plane perpendicular to the photographing optical axis, and the photographing optical axis. A control means for controlling incident light angles incident on the photographing optical system in two directions, which are orthogonal to each other in a horizontal plane and a vertical direction in a vertical plane, is provided, and a detection amount of shake of the image pickup apparatus by the detection means is provided. According to a first shake correction unit that changes the reading of the image pickup information from the CCD, and an incident light angle that is incident on the photographing optical system by the control unit according to a detected amount of shake of the image pickup apparatus by the detection unit. An image pickup apparatus comprising: a second shake correction unit for controlling. 2. The use of only the first shake correcting means, the use of only the second shake correcting means, and the simultaneous use of the first shake correcting means and the second shake correcting means. The image pickup apparatus according to claim 1, further comprising a selection unit that selects that the first shake correction unit and the second shake correction unit are not used together. 3. A means for detecting the focal length of the photographing optical system is provided, and the first shake correcting means and the second shake correcting means are automatically selected according to the value of the focal length. The image pickup apparatus according to claim 1, wherein 4. A means for detecting the focal length of the photographing optical system is provided, and the operation of each of the first shake correction means and the second shake correction means is automatically performed according to the value of the focal length. 2. The image pickup apparatus according to claim 1, wherein the weightings are different from each other. 5. The video image is constructed by removing horizontal scanning lines from all pixels of the CCD at regular intervals when the first shake correction means is not used. The imaging device described.