Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1989-08-28
1991-04-30
Groody, James J.
Facsimile and static presentation processing
Facsimile
Recording apparatus
358225, 354 70, 350500, H04N 5228, H04N 5225, G02B 1316, G03B 3900
Patent
active
050123475
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an image stabilizing apparatus for a portable video camera.
With the advanced miniaturization of video cameras, these cameras are becoming lighter and lighter in weight and can be carried by hand. Hence it can happen that if an operator viewing a predetermined subject moves, a slight displacement of the image of the subject on the target plate of the camera occurs. This translates into a corresponding displacement of the image on the receiver, resulting in a blurred image on the screen.
SUMMARY OF THE INVENTION
The invention overcomes the above problem by creating an image stabilizer for a portable video camera such that angular variations in the axis of the camera do not affect the output signal of the camera; that is, they definitively do not affect the position of the image with respect to the screen of the receiver.
In accordance with the invention, the apparatus for stabilizing images for a portable video camera is characterized in that for an angular variation .gamma. about the optical axis of the camera, and for vertical deflection currents Iy and horizontal deflection currents Ix of the camera in the absence of stabilization, the deflection currents are converted and take the following form: converted vertical deflection current, which are applied respectively to the corresponding horizontal and vertical deflection coils of the camera.
In accordance with other characteristics of the invention, the converted signals can also take into account rotational movements about a horizontal axis and a vertical axis perpendicular to the axis of the objective, or lens. Various other characteristics of the invention will become more apparent from the ensuing detailed description of exemplary embodiments of the invention, taken in conjunction with the drawings. It is understood that these exemplary embodiments are not to be considered as limiting the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of a portable video camera;
FIG. 2, on a larger scale, shows the target plate of the video camera of FIG. 1;
FIG. 3 is a block diagram of an embodiment of the image stabilizer according to the invention;
FIG. 4 is a block diagram of another embodiment of image stabilizer according to the invention;
FIG. 5 is a block diagram of a further embodiment of an image stabilizer according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 schematically shows a portable video camera and its main components, for the sake of better comprehension of the invention.
Hence the video camera includes an objective or lens 1, a target plate 2, an electron gun 3, and horizontal deflection coils 4 for scanning in the x direction, and vertical deflection coils 5 for scanning in the y direction, although these coils may also be deflection plates.
As is well known, a subject 6 outside the camera forms an optical image 7 on the target plate 2 of a video camera, and this optical image 7 is scanned by the cathode reading system of the camera with the aid of an electron beam emitted by the electron gun 3, which is deflected horizontally and vertically by the deflection coils 4 and 5 having vertical and horizontal fields, respectively.
FIG. 2, in broken lines, shows the target plate 2 that has undergone a rotation about the optical axis OZ of the camera. It should be noted here that to obtain compensation for the displacements of the position of the image on the target plate, i.e., its stabilization, it is necessary that the target area should be greater than the area of the optical image projected on it by means of the objective or lens 1.
The position of the target plate 2 of the camera may be defined in Cartesian coordinates, using a system of axes, x, y and z.
First, let it be assumed that between a time O and a time t, the camera has undergone an angular variation about its optical axis OZ.
A point in the optical image 7 on the plate 2 is defined at time O by its coordinates x.sub.O, y.sub.O, z. When this point ha
REFERENCES:
patent: 3577205 (1971-05-01), Hobrough
patent: 3619500 (1971-11-01), Bouley et al.
Greening Wendy R.
Groody James J.
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