JPH0427658B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a color picture tube device comprising a color picture tube having an in-line array of electron guns and a deflection device that deflects the electron beam in the horizontal and vertical directions to form a raster on a phosphor screen. In detail, it is a so-called automatic concentration type color picture tube device in which three electron beams are virtually automatically focused on the phosphor screen, and it is also a color picture tube device that improves the concentration error of the three electron beams and the focus quality around the screen. This invention relates to a picture tube device. [Technical Background of the Invention] Generally, a color picture tube has three
A phosphor screen 1 consisting of colored phosphor stripes, etc. is formed on the inner surface of the glass panel, and a shadow mask 2 having a large number of openings as color selection electrodes is arranged at a predetermined gap at the rear. An electron gun 3 that generates three electron beams arranged in a line in the horizontal direction is arranged. A deflection device 5 for electromagnetically deflecting the electron beam is arranged outside the glass funnel cone portion 4 . As shown in FIG. 2, the deflection device usually includes at least one pair of horizontal deflection coils 6, a pair of vertical deflection coils 7, and a deflection yoke core 8.
Since the deflection characteristics of the three electron beams and the concentration characteristics of the three electron beams are substantially determined by the magnetic field generated by this deflection device, determining the magnetic field distribution of the deflection device has an important meaning. In order to easily understand the present invention, some explanation will be given below regarding the concentration characteristics of the color picture tube and the magnetic field of the deflection device. As shown in FIG. 3, both side electron beams 9R and 9B emitted from the electron gun pass through a common deflection magnetic field, and when they reach the phosphor screen 10, a concentration error occurs, resulting in a concentration point 11 of the electron beams 9R and 9B. has a trajectory 12 curved toward the electron gun. To be more precise, the concentration point 1 of the electron beams 9R and 9B on both sides
0 and the central electron beam 9G do not necessarily coincide, and so-called coma aberration usually occurs. This phenomenon is shown in the pattern on the phosphor screen as shown in Figure 4. When discussing the concentration characteristics of color picture tubes, the magnetic field design of deflection devices, etc., it is qualitatively better to use the pattern on the phosphor screen. Yes, but easy to understand. In Fig. 4, R, G, and B in the center of the screen are the electron gun array seen from the fluorescent screen side, the x mark is the blue B beam, and the ○ mark is the green G beam.
The beam and △ mark indicate the red R beam, respectively. In a color picture tube device, in order to reproduce an accurate image, it is necessary to concentrate the three electron beams over virtually the entire surface of the phosphor screen. The mainstream is an automatic concentration method that takes advantage of the in-line electron gun and makes the deflection device magnetic field a special asymmetric magnetic field, thereby concentrating three electron beams substantially on the phosphor screen. Regarding automatic concentration, as shown in FIGS. 5A and 5B, the horizontal deflection magnetic field 13 is of the pink tension type,
It is well known that the vertical deflection magnetic field 14 can be a barrel-shaped magnetic field. Therefore, as shown in Fig. 5, if the tube axis of a color picture tube is the Z axis, the horizontal deflection direction is the X axis, and the vertical deflection direction is the Y axis (hereinafter the X, Y, and Z axes are defined as described above), the pink tube shape magnetic field 13
The magnetic field distribution in the cross section perpendicular to the tube axis increases as the distance from the center increases on the axis (A-A') as shown in Figures 5A and 6A and B, and at the same time, the magnetic field distribution increases as the distance from the center increases.
The magnetic field (B-B') measured along the X-axis direction from a point separated by an arbitrary distance in the axial direction shows a similar tendency. Furthermore, the (CC') magnetic field measured along the Y-axis direction from a point a given distance apart in the X-axis direction is a magnetic field that decreases with the off-axis distance, contrary to the above. Similarly, the barrel magnetic field has completely opposite characteristics to the pincushion magnetic field, as shown in FIGS. 5B and 6C and D. Some further explanation regarding the deflector magnetic field and automatic focusing will be provided using the three electron beam patterns on the phosphor screen. Figure 4 shows the pattern when the horizontal and vertical deflection magnetic fields are uniform, with three electron beams R,
G and B correspond to the trajectory of the concentration point shown in FIG. 3, and the horizontal, vertical, and diagonal axes are all overconcentrated in the horizontal direction. On the other hand, if the horizontal deflection magnetic field is of the pink-cushion type and the vertical deflection magnetic field is of the barrel type, the distance between the electron beam spots R and B on the horizontal, vertical, and diagonal axes gradually narrows, as shown in FIG. As a result, it changes in the direction of concentration. However, the relationship between the central beam G and both side beams R and B is not necessarily constant due to so-called coma aberration. When the horizontal and vertical deflection magnetic fields are simultaneously superimposed and the electron beam is deflected in the direction of the diagonal axis, the concentration characteristics at the ends of the diagonal axis vary depending on the deflection angle of the color picture tube, the screen size, etc., and cannot be generally determined. Therefore, we are trying to optimize the magnetic field by observing the concentration characteristics on the phosphor screen using an arbitrarily designed deflection device and making experimental corrections. As described above, color picture tubes can concentrate at least both side beams onto the phosphor screen by making the horizontal deflection magnetic field pink-shaped and the vertical deflection magnetic field barrel-shaped. It is also necessary to correct aberrations. Regarding the correction of this coma aberration,
As shown in Japanese Patent No. 26208, there is also known a method that utilizes the effect of a magnetic material placed on the electron gun electrode. [Problems with the Background Art] When the electron beam spot of a color picture tube is deflected using horizontal and vertical asymmetric magnetic fields as described above, the shape of the electron beam spot becomes distorted as the deflection progresses. FIGS. 8 and 9 show the shapes of electron beam spots when deflected by a uniform magnetic field and a non-uniform magnetic field. In contrast to the case of a uniform magnetic field shown in Fig. 8, when the electron beam is deflected by a non-uniform magnetic field, as shown in Fig. 9, at the horizontal edge of the screen, the upper half of the electron beam is directed downward and the lower half is directed upward by the pink tension type magnetic field. Under the pressure of Lorentzka, it is distorted into an ellipse with its long axis in the horizontal direction. Further, at the vertical edge of the screen, the right half of the electron beam is subjected to the Lorentz force that presses it to the right and the left half to the left due to the barrel-shaped magnetic field, and the electron beam is distorted into an ellipse with its long axis in the horizontal direction. This has the disadvantage that the focus quality at the periphery of the screen deteriorates. Table 1 shows the results of electron beam trajectory tracking using an electronic computer in order to examine in detail how the three electron beam concentration errors are corrected when the deflection device magnetic field is made non-uniform rather than uniform.

[Table] The color picture tube used here is a 20-inch type.
The horizontal deflection magnetic field is 30 Gauss, the vertical deflection magnetic field is 22 Gauss, the magnetic path length is 100 mm, and the non-uniform magnetic field is
This is the actual magnetic field of a deflection device for a 20-inch color picture tube. From Table 1, by making the deflection device magnetic field non-uniform rather than uniform, the horizontal concentration error at the horizontal and diagonal ends is almost corrected, but the horizontal concentration error at the vertical end remains almost unchanged. I understand. As a result of investigating the reason why the vertical deflection magnetic field is made into a non-uniform barrel shape to correct the horizontal concentration error at the vertical end, even though there is almost no horizontal concentration error at the vertical end with a uniform magnetic field.
The magnetic field in the Z direction of the tube axis at the end of the deflection device on the phosphor screen side works to overconcentrate the side beam, and in order to cancel this overconcentration error, the vertical deflection magnetic field is made into a non-uniform barrel shape. It became clear. FIG. 10 shows how the tube axis Z direction magnetic field at the phosphor screen side end of the deflection device becomes overly concentrated with respect to the side beam when deflected to the upper end of the vertical axis of the screen. Table 2 shows the calculation results of the effect of the tube axis direction magnetic field 15 on the side beam concentration error in the non-uniform vertical deflection magnetic field 14.

[Purpose of the invention]

As described above, the tube axis direction magnetic field of the color picture tube deflector adversely affects the concentration error of the side beam, and as a result, the vertical deflection magnetic field is made into a non-uniform barrel shape, and the periphery of the screen (particularly the upper and lower ends of the screen and the This was done in view of the fact that electron beam spot distortion occurs at the corner edges, degrading focus quality, and the purpose is to improve focus performance around the screen and side beam concentration errors. [Summary of the Invention] The present invention provides a deflection device that includes at least a pair of horizontal deflection coils, a pair of vertical deflection coils, and a deflection yoke core. By significantly reducing the magnetic field in the tube axis direction at the phosphor screen side end of the deflection device, the vertical deflection magnetic field is increased. This is a color picture tube device that reduces the non-uniformity of images. [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. Incidentally, since the overall configuration of the members of the color picture tube device of the present invention is the same as that shown in FIG. 1, the explanation of the overall configuration will be omitted and will not be repeated. FIG. 11 shows an embodiment of the deflection device according to the present invention, in which the inner diameter of the deflection yoke core 8 gradually increases along the tube axis direction from the electron gun side to the phosphor screen side, and vice versa at the phosphor screen side end. It gradually decreases as it progresses in the tube axis direction. As shown in Figure 10, the core inner diameter 8 of the conventionally used deflection yoke continues to gradually increase as it progresses in the tube axis direction, so a vertical deflection magnetic field at the end of the phosphor screen is inevitable. It has a convex shape toward the phosphor screen and acts to overconcentrate the side beam. When the deflection yoke core shown in Fig. 11 is used, a convex vertical deflection magnetic field is generated toward the electron gun side, as shown by the thick line in the figure, in the region where the inner diameter of the core is of the opposite grade at the end on the phosphor screen side. , works to unfocus the side beam. The greater the degree of inversion of the inner diameter of the core at the phosphor screen side end, the weaker the effect of overconcentration on the side beam, but since it is in the opposite direction to the shape of the glass funnel cone, it is subject to spatial constraints. As a result of examining the horizontal concentration error at the screen horizontal axis end and diagonal axis end by forming the inner diameter of the core at the phosphor screen side end to a reverse grade under the above spatial constraints,
The degree of overconcentration has been reduced by 30 to 40% compared to conventional methods. This reduces the nonuniformity (barrel shape) of the vertical deflection magnetic field in the cross section perpendicular to the tube axis, improving electron beam spot distortion at the vertical and diagonal ends of the screen, resulting in good peripheral focus. is obtained. Furthermore, since the nonuniformity of the vertical deflection magnetic field can be weakened, it becomes easy to design a deflection device that eliminates side beam concentration errors, and as a result, good concentration characteristics can be obtained. [Effects of the Invention] As described above, the present invention provides a completely new automatic focusing color picture tube device by controlling the shape of the magnetic field in the tube axis direction of the deflection yoke core, which has received little attention in the past. The value is extremely large.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view showing the configuration of a color picture tube device, Fig. 2 is a schematic perspective view showing the configuration of a deflection device, Fig. 3 is a schematic diagram for explaining the concentration characteristics of an electron beam, and Fig. 4 is a schematic diagram showing FIG. 3 as a pattern on a fluorescent screen, FIGS. 5A and 5B are schematic diagrams showing the horizontal deflection magnetic field and vertical deflection magnetic field, respectively, and FIGS. A- in Figure 5 A
Characteristic diagrams showing the magnetic field distribution cut by A' line, B-B' line and C-C' line, respectively. Figure 6C and Figure 6D are D-D' line and E-E of Figure 5B. Characteristic diagrams showing the magnetic field distribution cut along the ' line and the F-F' line, Figure 7 is a schematic diagram to explain the pattern trend on the phosphor screen in a non-uniform magnetic field, Figures 8 and 9 are A schematic diagram for explaining the trends of the beam spot shape on the phosphor screen in a uniform magnetic field and a non-uniform magnetic field, respectively; FIG. 10 is a partially enlarged schematic diagram for explaining the vertical deflection magnetic field characteristics of a conventional deflection device; FIG. 11 is a schematic diagram for explaining the vertical deflection magnetic field characteristics of the deflection device applied to the present invention. 1... Fluorescent screen, 2... Shadow mask, 3...
Electron gun, 4...Funnel, 5...Deflection device, 6
...Horizontal deflection coil, 7...Vertical deflection coil, 8
...deflection yoke core.

Claims (1)

[Claims] 1. A color picture tube equipped with an in-line electron gun arranged horizontally and generating at least one pair of side beams and a center beam, and a fluorescent tube that scans and deflects the electron beam in the horizontal and vertical directions and faces the electron gun. In a color picture tube device comprising a deflection device that forms a raster on a surface, the deflection device includes at least a pair of horizontal deflection coils, a pair of vertical deflection coils, and a deflection yoke core,
The inner diameter of the deflection yoke core gradually increases as it moves from the electron gun side to the phosphor screen side in the tube axis direction,
The color picture tube device is characterized in that the end portion on the phosphor screen side gradually decreases in the tube axis direction.