JPH0127343Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a beam index type color television receiver.

FIG. 1 shows the structure of a beam index type color picture tube. On the inner surface of the face plate 1, three primary color phosphor stripe layers 2 (in the figure perpendicular to the plane of the paper) are formed, each sandwiched between non-luminescent material stripes, and on the inner surface thereof, a thin aluminum film 3 is formed. There is. Furthermore, an index phosphor stripe 4 that emits ultraviolet light for detecting the scanning position of the beam is arranged on the inner surface of this aluminum thin film. Further, a single electron gun 6 is installed inside the network portion 5. A deflection device 7 is installed to horizontally and vertically scan the electron beam emitted from the electron gun and reproduce an image on the fluorescent surface. next,
The deflection aberration characteristics required for a beam index type color receiver will be explained. The beam spot diameter in a beam index type color receiver is the second
As shown in Figure a, the width of one phosphor stripe 11 and the width of the black guard bands 12 on both sides must be less than 13. This is because if the beam spot diameter is larger than this, other unnecessary phosphors will also be irradiated and the color purity of the reproduced color will deteriorate. Even if the spot diameter of the electron beam satisfies this requirement when there is no deflection, that is, at point a in the center of the phosphor screen shown in FIG. At point b in the corner of the screen, the shape of the electron beam spot changes due to deflection aberration as shown by the broken line in Figure 2b, and the spot size in the direction perpendicular to the phosphor stripe (x direction) increases.
This results in a decrease in color purity. Therefore, it is necessary to minimize the increase in the spot size in the x direction regarding the deflection aberration of the beam index method. An increase in spot size in the y direction is allowed to the extent that it allows resolution in the vertical direction. Therefore, in a beam index type color television receiver, it is desirable to have a deflection aberration that results in a vertically elongated spot shape as shown by the solid line in FIG. 2b. This applies not only to the corners of the fluorescent screen, but also to all parts. Regarding raster distortion, for example, if there is pincushion distortion on the left and right sides as shown by the broken lines in Figure 2c, the frequency of the index signal during horizontal scanning at the center of the screen will be higher than that during horizontal scanning at the top and bottom of the screen. The frequency of the index signal becomes higher, and the overall frequency band becomes wider. As the frequency band of the index signal becomes wider, it becomes difficult to design a filter circuit for extracting the index signal, and the S/N ratio decreases. Therefore, especially in index-type color television receivers, raster distortion in the left and right direction is reduced, and the frequency band of the index signal is It is necessary to narrow the band.

The present invention proposes a beam index type color television receiver with a vertically elongated spot shape and a deflection magnetic field distribution that results in less left and right raster distortion and deflection aberration.

As shown in Figure 1, the z-axis is taken along the tube axis of the phosphor toward the screen, and the x-axis is taken in the horizontal deflection direction.
axis, the y-axis is taken in the vertical deflection direction (Figure 2b).

Generally, for horizontal and vertical deflection magnetic fields, a magnetic field in which the magnetic flux density becomes stronger as one moves from the z-axis in the deflection direction is called a pink tension magnetic field, and the opposite is called a barrel magnetic field. The horizontal axis is the tube axis (z-axis), and the pink tension magnetic field is shown above.
Take the barrel magnetic field downward and determine the height of the curve depending on the strength of each field. For example, in the case of a combination of horizontal and vertical magnetic fields of the barrel magnetic field as shown in FIG. 3, the raster 14 and spot shapes 15, 16, 1 as shown in FIG.
It will be 7.18. That is, the raster distortion becomes a pink distortion distortion, and the spot shape becomes an ellipse 16, 17 that is long in the deflection direction due to the astigmatism distortion, and becomes an ellipse 18 that is inclined at the corner. FIG. 5 shows a cross section of the neck tube of the horizontal deflection magnetic field of the barrel magnetic field.

In general, a barrel magnetic field forms an ellipse that is long in the deflection direction due to astigmatism, and a pink tension magnetic field forms an ellipse that is short in the deflection direction. Furthermore, raster distortion becomes pink tension distortion in a barrel magnetic field, and becomes barrel distortion in a pink tension magnetic field. Regarding raster distortion, the influence of the magnetic field distribution on the screen side opening of the deflection yoke is stronger than on the electron gun side. Therefore, as mentioned above, in order to reduce the increase in the beam spot in the x direction and form a vertically elongated spot shape, it is necessary to use a barrel magnetic field for the vertical coil and a pincushion magnetic field for the horizontal coil due to astigmatism. However, in this combination, although the pink tension horizontal deflection magnetic field is in the direction of eliminating raster distortion, the barrel vertical magnetic field causes strong pink tension distortion. Therefore, a simple combination of a horizontal pink tension magnetic field and a vertical barrel magnetic field cannot provide the optimum magnetic field distribution for a beam index type color receiver.

The present invention has been developed in view of the above points, and provides a beam index type color television receiver in which the vertically elongated beam spot is not tilted even at the periphery of the screen, and furthermore, no raster distortion occurs. This is what I am trying to do.

Figure 6 shows the magnetic field distribution of the deflection coil used in the present invention, and figure a shows the horizontal deflection coil (H
Figure b shows the magnetic field distribution of the vertical deflection coil (V coil).

As can be seen from Figure 6b, the vertical deflection magnetic field produced by the vertical coil is largely a barrel magnetic field on the neck side, a slight pink tension magnetic field on the front (screen) side, and a barrel magnetic field as a whole in the Z-axis direction. ing. On the other hand, the horizontal deflection magnetic field generated by the horizontal deflection coil is largely a pink tension magnetic field on the neck side, slightly becomes a barrel magnetic field on the front (screen) side, and is a pink tension magnetic field as a whole in the Z-axis direction.

In this way, the vertical deflection coil as a whole has a barrel magnetic field, and the horizontal deflection coil as a whole has a pink tension magnetic field, so that the beam spot due to astigmatism becomes vertically elongated, and as a result, the screen The beam spots at each point are all vertically elongated as shown in FIG. 7 corresponding to FIG. This is in the same direction as the tricolor phosphor stripes.

In addition, it has been confirmed that the magnetic field on the oven side of the deflection coil has a large influence on raster distortion, and in this invention, the magnetic field distribution on the oven side is changed to the pink tension magnetic field on the front side of the vertical deflection coil as described above. Since the barrel magnetic field is used in front of the horizontal deflection coil, pincushion distortion on the left and right sides of the raster is removed.

As described above, according to the present invention, raster distortion is eliminated and the tilt of the beam spot is eliminated, so that an image with good color purity can be obtained, and is therefore preferably effective.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing a picture tube used in a beam index type color television receiver. Figures 2, 3, 4 and 5 are
It is an explanatory view of a figure. FIG. 6 is a diagram for explaining the magnetic field of the deflection coil used in the present invention, and FIG. 7 is a diagram for explaining the raster and beam spot. 1... Face plate, 2... Three primary color phosphor stripes, 4... Index phosphor stripes, 7... Deflection device, 12... Guard band, 1
6, 17, 18... Beam spots around the screen.

Claims (1)

[Scope of utility model registration request] The three primary color phosphors of red, green, and blue are repeatedly arranged in stripes on the inner surface of the face plate of the picture tube, sandwiching a black guard band, and the phosphors are arranged repeatedly in stripes in a regular relationship with these phosphors. When an electron beam emitted by a single electron gun is scanned over a surface consisting of an index element, a color signal is synthesized with an index signal obtained from the index element, and the electron beam based on the color signal emits a predetermined fluorescent light. In a beam-indexed color television receiver designed to impact the body, a horizontal deflection coil is used, which has the characteristics of a pink tension magnetic field as a whole in the axial direction, but a parallel magnetic field on the front side near the face plate; The beam index uses a vertical deflection coil that has the characteristics of a parallel magnetic field but a pink tension magnetic field on the front side, so that the beam spot shape due to astigmatism becomes vertically elongated in the same direction as the phosphor stripe around the screen. type color television receiver.