JPS5932857B2 - Manufacturing method of color picture tube - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a color picture tube.

Conventionally, as shown in Fig. 1, an exposure device used to form the fluorescent screen of a color picture tube places a light source 1 at a position corresponding to the center of deflection of the color picture tube, and measures the light emitted from this light source 1. A correction lens 2 to match the final trajectory of the electron beam deflected by the deflection yoke of the color picture tube.
The phosphor screen 5 of the panel 3 coated with the photosensitive phosphor film is irradiated through the shadow mask 4 and developed to form phosphor dots.

The correction lens 2 used here must be designed to minimize the landing error, but there are cases where it is impossible to correct it with a conventional continuous curved surface correction lens.

This will be explained using FIG.

The arrow shown in Figure 2A is the distance from the center 6 of the phosphor dot in Figure 2B to the center 7 of the electron beam (landing error amount).
shows roughly similar size and direction.

Now, as you can see from Figure 2A, the screen center 8 and the X-axis end 9
The landing error is O at the corner part 10 and the middle part 11, but it is maximum at the Y-axis upper end part 12, and the landing error amount gradually decreases from there toward the corner part 10. The size has a minimum value of 0 at
The direction is a radial direction from the center 8 of the screen.

Such landing errors are generally common when using an in-line self-convergence type deflection yoke, and
This occurs because the deflection yoke has a complex magnetic field distortion so that the two electronic beats t are concentrated at the screen position and the image distortion is minimized.

Therefore, in order to minimize the landing error, the design of the correction lens was modified, and as a result, the phosphor dots moved in a direction and size similar to the arrows shown in FIG.

Therefore, the landing error is 0 at the upper end 12 of the Y axis,
In addition, the landing error decreased and became the minimum in most areas of the screen, including areas that did not require correction, but only around the middle point 13, the landing error increased in the X direction. I end up.

This is because since the lens surface is a continuous curved surface, the lens surface inclination in the X direction that occurs secondarily is opposite to the desired inclination.

As described above, the landing error shown in FIG. 2 cannot be corrected by a continuous lens.

However, if it is a discontinuous surface lens that has been used in some areas, it is easy to correct, but it requires a large number of mold jigs and tools for lens machining, and it also costs a large amount of money. There are many restrictions on the use of discontinuous surface lenses, such as the need for a mechanism to eliminate the shadows on the fluorescent screen caused by this.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a color picture tube with good color purity by eliminating the conventional drawbacks.

In the exposure of a phosphor screen, the present invention limits the exposure area using a light blocking plate with long openings in the X-axis direction, and moves the light source in the tube axis direction of the color picture tube in synchronization with the movement of the exposure area. The present invention is characterized in that the mislanding is corrected in a required area and the exposure is performed.

An embodiment of the present invention will be described with reference to FIG.

A light source 1', which moves up and down in the direction of the tube axis (Z-axis) of the color picture tube in synchronization with the movement of the light-shielding plate 14 having a long opening in the X-axis direction, is placed at a position corresponding to the center of deflection. The light emitted from the light source is transmitted to the inner surface of the panel 3' through a correction lens 2' for matching the final trajectory of the deflected electron beam of the color picture tube and an aperture in a shadow mask 4 attached to the panel 3. The applied photoresist film 5 is exposed to light.

The light shielding plate 14 is reciprocated in the X direction via the mounting base of the plate cam 16 and the support 15 by a combination of a reciprocating motor 17, a rack, and a pinion 18, and at the same time, the light source support shaft is moved by the convex part of the plate cam 16. Move 19 up and down.

The shape of the convex portion of the plate cam 16 is determined by the amount of landing error that needs to be corrected.

The light source moves dz in the Z-axis direction and the landing error amount is dr.
When corrected, the following relationship holds true.

d, -9°sinθ”dZ,,・<1> (L-q) °cos(θ-ψ)-cosψ-dzL
sinθ ψ−5in'() ・・・・・・(2
) Here, L is the distance between the inner surface of the panel and the center of deflection, q is the distance between the inner surface of the panel and the shadow mask, θ is the deflection angle of the exposure point, and R is the radius of curvature of the inner surface of the panel.

Here, compared to L, dz is very small with a coefficient of less than 1 (
Equation 1) can be approximated by the following equation.

sinθ dr−□・□・dz ・・・・・・(3) L−
qcos(θ-ψ) Therefore, for example, the coordinates of the point 13 at the midpoint between the upper end 12 of the Y axis of the 16-inch 90° screen and the corner part 10 (80 mm, 120
Calculating the dz that corrects the landing error of 15 microns when exposing 15 mm) is L - 254 mm, R = 631
From millimeter, q=s, o millimeter, d z=0.75 mi'J.

Next, since the dr is 25 microns at the Y-axis upper end 12 where the amount of error is the largest, dz may be set to 1.4 microns IJ by the same calculation.

In this way, dZ is determined according to the amount of landing error,
Further, by finely adjusting dz so that the size of the error is minimized over the entire screen, the phosphor dots can be appropriately placed.

The color picture tube manufactured in this way has an extremely good landing condition.

As described above, according to the present invention, it is possible to easily correct the landing error that cannot be corrected with a conventional continuous surface correction lens, and the amount of correction can be freely changed by changing the shape of the convex part of the plate cam. Using an exposure device with advantages such as
A method for manufacturing a color picture tube can be provided.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of a conventional color picture tube phosphor film exposure device, Figures 2A and B are explanatory diagrams showing the landing error of a color picture tube, and Figure 3 is a diagram showing the landing error of a color picture tube. FIG. 4 is an explanatory diagram showing the movement of phosphor dots when a new lens is designed to minimize the amount of phosphor dots. FIG. 4 is a sectional view of an exposure apparatus used in the method of manufacturing a color picture tube of the present invention. 1.1'... Light source, 2.2'... Correction lens, 14... Shade plate, 16... Plate cam, 17... ··motor.

Claims (1)

[Claims] 1. A light shielding plate that limits the exposure area in the direction of arrangement of the inline electron guns of a color picture tube having an inline electron gun is placed between the exposure surface and the exposure source, and the light shielding plate is moved in the direction of arrangement of the inline electron guns. A method for manufacturing a color picture tube, comprising the step of performing phosphor screen exposure using an exposure device configured to move an exposure source position in the axial direction of the color picture tube.