JPH0459739B2 - - 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 for deflecting an electron beam in horizontal and vertical directions to form a raster on a fluorescent surface. Specifically, it is a so-called automatic focusing type color picture tube device in which three electron beams substantially automatically focus on a fluorescent surface, and it also improves the concentration error of the three electron beams and the focus quality around the screen. This invention relates to a color picture tube device. [Technical Background of the Invention] Generally, a color picture tube has three
A fluorescent surface 1 consisting of colored phosphor stripes or the like is formed on the inner surface of the glass panel, and further behind a shadow mask 2 having a large number of openings as color selection electrodes is arranged at a predetermined interval. An electron gun 3 that generates three electron beams arranged in a row in the horizontal direction is disposed. 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 is usually composed of at least one pair of horizontal deflection coils 6, a pair of vertical deflection coils 7, and a deflection yoke core 8 made of a magnetic core, and has the deflection characteristics of the three electron beams as well as the deflection characteristics of the three electron beams. Since the concentration characteristics of the three electron beams are almost 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 beams 9R and 9B emitted from the electron gun pass through a common deflection magnetic field, and when they reach the fluorescent surface 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. More precisely, the concentration point 10 of both side electron beams 9R and 9B does not necessarily coincide with the central electron beam 9G, and so-called coma aberration usually occurs. Figure 4 shows this phenomenon using a pattern on a fluorescent surface. When discussing the concentration characteristics of a color picture tube, the magnetic field design of a deflection device, etc., it is better to use the pattern on a fluorescent surface to obtain qualitative information. Although it is basic, it is easy to understand. In Figure 4, the RGB in the center of the screen is the electron gun arrangement seen from the fluorescent surface side, the x mark is the blue B beam, the ○ mark is the edge G beam, and the △ mark is the blue B beam.
Each mark indicates a red R beam. In a color picture tube device, in order to reproduce images accurately, it is necessary to concentrate the three electron beams over virtually the entire surface of the fluorescent surface, and a method of correcting moving point concentration using a correction circuit, etc. Since then, an automatic concentration method has become mainstream, which takes advantage of the in-line type electron gun and makes the deflection device magnetic field a special asymmetric magnetic field, thereby concentrating three electron beams substantially on the fluorescent surface. Regarding automatic concentration, it is well known that the horizontal deflection magnetic field 13 can be a pincushion magnetic field, and the vertical deflection magnetic field 14 can be a barrel-shaped magnetic field, as shown in FIGS. 5A and 5B. 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 The shape magnetic field 13 has a magnetic field distribution in a cross section perpendicular to the tube axis, as shown in FIGS. A magnetic field B-B' measured along the X-axis direction from a point separated by an arbitrary distance in the axial direction also shows a similar tendency. Furthermore, the C-C' magnetic field measured along the Y-axis direction from a point separated by an arbitrary distance 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 surface. 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 use an arbitrarily designed deflection device to observe the concentration characteristics on the fluorescent surface and make experimental modifications to optimize the magnetic field. As described above, color picture tubes can concentrate at least both side beams onto the fluorescent surface by making the horizontal deflection magnetic field pink-shaped and the vertical deflection magnetic field barrel-shaped. , it is also necessary to correct coma aberration. Regarding the correction of this coma aberration,
As shown in Japanese Patent No. 26208, there is also known a means of utilizing 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 nonuniform 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. It is distorted into an elliptical shape with its long axis in the horizontal direction due to the pressing Lorentzka. At the vertical edge of the screen, the barrel-shaped magnetic field pushes the right half of the electron beam to the right and the left half to the left, causing it to be distorted into an elliptical shape 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 the state in which 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. Table 1 shows that 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 examining the reason why the vertical deflection magnetic field is made into a non-uniform barrel shape to correct the horizontal direction concentration error at the vertical end, even though there is almost no horizontal concentration error at the vertical end with a uniform magnetic field, we found that the deflection The magnetic field in the Z-direction of the tube axis at the end of the fluorescent surface side of the device works to overconcentrate the side beam, and in order to cancel this overconcentration error, the vertical deflection magnetic field is shaped into a non-uniform barrel shape. has become clear. 1st
Figure 0 shows how the magnetic field in the Z direction of the tube axis at the end of the deflection device on the fluorescent surface side becomes overly concentrated with respect to the side beam when the deflection device is 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 corners (corners), which degrades 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. Or, an auxiliary deflection element consisting of at least one pair of magnetic pieces is arranged in a space substantially corresponding to the diagonal axis, and the auxiliary deflection element is arranged so as to significantly reduce the magnetic field in the tube axis direction at the fluorescent surface side end of the deflection device. A collar that weakens the nonuniformity of the vertical deflection magnetic field and makes it easier to substantially concentrate the electron beam on the fluorescent surface by narrowing the distance between the elements on the fluorescent surface side compared to the inner diameter of the fluorescent surface of the deflection yoke core. It is a picture tube device. [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 5 according to the present invention, which is made up of a pair of magnetic pieces located near the fluorescent surface side end of the deflection yoke core 8 at a location substantially corresponding to the horizontal or diagonal axis of the color picture tube. Auxiliary deflection element 16
are arranged, the auxiliary deflection elements 16 extend in the tube axis direction, and the interval between the pair of auxiliary deflection elements 16 becomes narrower as it progresses in the tube axis direction, and the end portion on the fluorescent surface side is connected to the fluorescent surface of the deflection yoke core 8. It is narrower than the inner diameter on the light side. Conventionally, the deflection device used is the 10th
As shown in the figure, the 8 inner diameter of the deflection yaw continues to gradually increase as it advances in the tube axis direction, so the vertical deflection magnetic field at the end on the fluorescent surface side will inevitably have a convex shape toward the fluorescent surface side. It acts as if it becomes overly focused on the side beam. When the auxiliary deflection element 16 consisting of the pair of magnetic pieces shown in FIG. Since the edge on the fluorescent surface side is narrower than the inner diameter on the fluorescent surface side of the deflection yoke core 8, the vertical deflection magnetic field is changed in a convex shape toward the electron gun side, as shown by the thick line in the figure, and the side beam is It works in a way that makes you unconcentrated. The narrower the distance between the pair of auxiliary deflection elements 16 in the tube axis direction is, the more the effect of excessive concentration on the side beam can be weakened. subject to physical constraints. As a result of considering the shape of the auxiliary deflection element under the above spatial constraints and investigating the horizontal concentration error at the screen horizontal axis end and diagonal axis end, the degree of overconcentration was reduced by 20 to 40% compared to the conventional one. did it. From this, the nonuniformity of the vertical deflection magnetic field in the cross section perpendicular to the tube axis (barrel shape)
Since this can reduce the electron beam spot distortion at the vertical axis end and diagonal axis end of the screen, good peripheral focus can be obtained. Furthermore, since the nonuniformity of the vertical deflection magnetic field is weakened, it becomes easier 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 overall shape of the tube axial magnetic field of the deflection yoke core, which has received little attention in the past. Its industrial value is extremely large.

[Brief explanation of the drawing]

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 Figure 3 as a pattern on a fluorescent surface, Figures 5A and 5B are schematic diagrams showing a horizontal deflection magnetic field and a vertical deflection magnetic field, respectively, and Figures 6A and 6B are schematic diagrams showing a horizontal deflection magnetic field and a vertical deflection magnetic field, respectively. A- in Figure 5A
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, respectively. Figure 7 is a schematic diagram for explaining pattern trends on the fluorescent surface in a non-uniform magnetic field. Figures 8 and 9. Figure 10 is a schematic diagram for explaining the trends of the beam spot shape on the fluorescent surface in a uniform magnetic field and a non-uniform magnetic field, respectively, and Fig. 10 is a partially enlarged diagram for explaining the vertical deflection magnetic field characteristics of a conventional deflection device. 11 are schematic diagrams for explaining the vertical deflection magnetic field characteristics of the deflection device applied to the present invention. DESCRIPTION OF SYMBOLS 1... Fluorescent surface, 2... Shadow mask, 3... Electron gun, 4... Funnel, 5... Deflection device, 6... Horizontal deflection coil, 7... Vertical deflection coil, 8... Deflection yoke core, 16... Auxiliary deflection element.

[Claims]

1. A large number of sets of three primary color phosphor stripes of red, green, and blue repeatedly arranged in a fixed order at a positional phase of 120 degrees from each other, a phosphor screen with a metal back layer behind it, and vertical scanning of such a phosphor screen. an electron gun that generates a horizontally long band-shaped electron beam in the direction along the surface; a deflector that changes the direction of the electron beam from the electron gun to a direction substantially perpendicular to the phosphor screen; A color picture tube comprising a matrix modulation section, and electrostatic shielding electrodes on the phosphor screen side and the opposite side of the matrix modulation section. 2. The matrix modulation section has n sets of electrode groups in which a plurality of striped electrodes having n (n is an integer of 2 or more) slit-like openings are divided from each other at the same pitch and arranged in parallel; 2. A color picture tube according to claim 1, wherein said n sets of electrode groups are arranged with their openings sequentially shifted by 1/n pitch in the horizontal direction.