Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Reexamination Certificate
2000-03-30
2001-12-04
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
C315S371000
Reexamination Certificate
active
06326745
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-092729, filed Mar. 31, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a cathode-ray tube apparatus for displaying color pictures or monochrome pictures by deflecting a plurality of electron beams or a single electron beam emitted from an electron gun by means of a deflecting yoke, and more particularly to a cathode-ray tube apparatus compensating the difference of distortion between the intermediate portion and the peripheral portions of the display screen.
Generally, the color cathode-ray tube apparatus comprises a vacuum envelope having a substantially rectangular panel on whose inner surface a phosphor screen is formed, a funnel, and a cylindrical neck, and it displays color pictures by deflecting a plurality of electron beams emitted from an electron gun arranged in the neck by means of a deflecting yoke disposed from the outer surface of the reduced-diameter portion of the funnel to the neck, and by scanning the phosphor screen through a shadow mask horizontally and vertically. Further, in the monochrome cathode-ray tube apparatus, the electron gun emits a single electron beam, and the shadow mask of the color cathode-ray tube apparatus is omitted therefrom.
In such a cathode-ray tube apparatus, the traveling length of the electron beams deflected to the diagonal ends of the phosphor screen is the longest, and they pass the nearest position from the deflecting coils of the deflecting yoke. Thus, the raster which should be essentially rectangular is distorted to a pin cushion shape. Usually, in order to correct this distortion, magnets having a polarity of assisting a vertical deflection are disposed on and under the opening of the phosphor screen side of the deflecting yoke, and compensates the distortion on the upper and lower ends of the raster (hereinafter, the distortion is called as North-South distortion, i.e., NS distortion). Further, the distortion on the left and right ends of the raster (hereinafter, the distortion is called as East-West distortion, i.e., EW distortion) is compensated by changing the horizontal deflecting voltage dynamically.
However, since the correction of distortion by means of magnets is weaker in the vertically intermediate portion compared with the upper and lower peripheral portions of the picture, there is a distortion called “Inner Kissen Distortion” in the intermediate portion. As a result, there is a difference of distortion between the vertically intermediate portion and the peripheral portion of the picture.
This difference of distortion has been noticeable in recent wide deflection angle color cathode-ray tube apparatus and color cathode-ray tube apparatus having a flat screen.
BRIEF SUMMARY OF THE INVENTION
The present invention has been contrived in consideration of the above circumstances, and its object is to provide a cathode-ray tube apparatus capable of compensating the difference of distortion between the intermediate portion and the peripheral portions of the screen.
In order to attain the above-described object, a cathode-ray tube apparatus according to the present invention comprises a vacuum envelope including a substantially rectangular panel having a phosphor screen on an inner surface thereof and also having a horizontal and a vertical axis, a funnel fixed to the panel and a neck connected to the reduced-diameter portion of the funnel; an electron gun arranged in the neck, for emitting electron beams towards the phosphor screen; a deflecting yoke mounted on a reduced-diameter portion of the funnel and on the circumference of the neck, for deflecting the electron beams so that the phosphor screen is scanned in the horizontal and vertical directions, the deflecting yoke having horizontal deflecting coils for deflecting the electron beams in the horizontal direction, and vertical deflecting coils for deflecting the electron beams in the vertical direction; and a modulator having saturated coils connected to the horizontal deflecting coils, a saturating control coils connected to the vertical deflecting coils, saturable cores around which the saturated or saturating control coils are wound, and magnets biasing the saturable cores magnetically,
wherein the modulator has different settings in an intermediate portion and in peripheral portions of a picture formed on the phosphor screen so that the change of inductance the saturating control coils in the horizontal axis direction or the change of inductance of the saturated coils in the vertical axis direction compensates the difference of NS distortion between the intermediate portion and the peripheral portions of the picture with respect to the vertical axis direction or compensates the difference of EW distortion between the intermediate portion and the peripheral portions of the picture with respect to the horizontal axis direction.
Further, another cathode-ray tube apparatus according to the present invention comprises a vacuum envelope including a substantially rectangular panel having a phosphor screen on an inner surface thereof and also having a horizontal and a vertical axis, a funnel fixed to the panel and a neck connected to the reduced-diameter portion of the funnel; an electron gun arranged in the neck, for emitting electron beams towards the phosphor screen; a deflecting yoke mounted on a reduced-diameter portion of the funnel and on the circumference of the neck, for deflecting the electron beams so that the phosphor screen is scanned in the horizontal and vertical directions, the deflecting yoke having horizontal deflecting coils for deflecting the electron beams in the horizontal direction, and vertical deflecting coils for deflecting the electron beams in the vertical direction; and a distortion compensating element having horizontal auxiliary coils connected to the horizontal deflecting coils, vertical auxiliary coils connected to the vertical deflecting coils, saturable cores around which the horizontal or vertical auxiliary coils are wound, and magnets biasing the saturable cores magnetically,
wherein the distortion compensating element has different settings in an intermediate portion and in peripheral portion of a picture formed on the phosphor screen so that the change of inductance of the horizontal auxiliary coils in the horizontal axis direction or the change of inductance of the vertical auxiliary coils in the vertical axis direction on the phosphor screen compensates the difference of NS distortion between the intermediate portion and the peripheral portions of the picture with respect to the vertical axis direction or compensates the difference of EW distortion between the intermediate portion and the peripheral portions of the picture with respect to the horizontal axis direction.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
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Chen Shih-Chao
Kabushiki Kaisha Toshiba
Philogene Haissa
Pillsbury & Winthrop LLP
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