JPH088062B2 - Exposure device for forming fluorescent screen of color picture tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exposure apparatus for forming a fluorescent screen of a color picture tube, and more particularly to a spherical surface having slot-shaped through holes linearly arranged through a bridge. The present invention relates to an exposure apparatus for forming a fluorescent screen of a color picture tube, which is used to form a stripe-shaped phosphor layer or a light absorption layer (black material layer) on the inner surface of a spherical panel by using the shadow mask.

[Technical background of the invention and its problems]

The phosphor layer constituting the phosphor screen of the color picture tube was coated with phosphor slurry using a sensitized photosensitive resin on the inner surface of the panel, and the coating film was exposed through a shadow mask to expose the photosensitive resin. It is formed after development. In addition, a black material layer is usually formed between the phosphor layers in the same manner as the phosphor layer in order to improve the contrast.

In the above exposure, a spherical shadow mask in which slot-shaped through holes are linearly arranged through a bridge is used, and a spherical panel corresponding to the array of the slot-shaped through holes of the shadow mask is used. When a fluorescent surface composed of a stripe-shaped fluorescent material layer or a black material layer is formed on the inner surface of the, a long linear light source elongated in the direction of arrangement of the slot-shaped through holes is usually used as the light source. However, when such a long light source is used, the projection of the long light source onto the inner surface of the panel is rotated due to the three-dimensional geometrical relationship based on the shapes of the light source, the shadow mask, the panel, etc., and as shown in FIG. In particular, meandering stripes (2) are formed at the corners of the panel (5). As a result, the landing characteristic of the electron beam is impaired, and a color picture tube with poor color purity is obtained.

Conventionally, various techniques for correcting the meandering of the stripe (2) have been developed. As an example thereof, there is an exposure apparatus in which a negative meniscus lens (4) is arranged so as to cover the light source (3) as shown in FIG. According to this exposure apparatus, the sixth
As shown in FIGS. (A) and (B), the negative meniscus lens (4) has radii R ₁ and R _{2 on its} inner surface and outer surface, respectively.
The light reaching the panel (5) from the light source (3) is shown by a broken line in FIG. 6 (B) because it forms an approximate spherical surface (where R ₁ <R ₂ ) and has a dome shape with 360 ° rotational symmetry. As described above, the projection of the long light source (3) onto the inner surface of the panel (5) can be reduced by increasing the distance from the actual light source position by different distances corresponding to each point of the long light source. Radius R ₁ , R ₂
By properly selecting, the meandering of the stripe (2) can be corrected.

In FIG. 5, (6) is a landing correction lens, (7) is a light distribution correction filter, and (8) is a shadow mask.

Although it is possible to correct the meandering of the stripe (2) by using the exposure apparatus equipped with the negative meniscus lens (4) as described above, even if the meandering of the stripe (2) is corrected, FIG. As shown in, when light is irradiated using the shadow mask (8) in which the slot-shaped through holes (10) are arranged through the bridge (11), the long elongated holes are elongated in the arrangement direction of the slot-shaped through holes (10). Even if the light source (3) is used, the inner surface of the panel (5) has different irradiation doses corresponding to the through hole (10) and the bridge (11). The striped stripes (2) are narrowed.

In order to correct this constriction, it is necessary to make the irradiation amount uniform, and for this purpose, the length (l) of the long light source (3) can be calculated by the following equation.

Here, L ₀ is the distance from the long light source (3) to the inner surface of the panel (5), q is the distance from the shadow mask (8) to the inner surface of the panel, and P is the pitch along the longitudinal direction of the slot-shaped through hole (10). Is. However, Lo / q is not constant over the entire screen, and becomes large in the periphery in the direction along the longitudinal direction of the long light source (3) and becomes small in the periphery in the direction orthogonal to the longitudinal direction. Among these, in the direction orthogonal to the longitudinal direction of the light source (3), the stripe (2) is adjusted to the optimum light source length by changing the shape of the light source cover of the long light source (3).
Although it is possible to correct the constriction, there is a problem that a constriction occurs in the periphery in the direction along the longitudinal direction, which deteriorates the screen quality of the color picture tube.

[Object of the Invention]

This invention has been made in view of the above problems,
An object of the present invention is to provide an exposure device for forming a fluorescent screen of a color picture tube, which can correct not only the meandering of stripes but also the constriction by improving the negative meniscus lens.

[Outline of Invention]

The present invention sequentially corrects the trajectory of light emitted from an elongated long light source along the Y-axis by a negative meniscus lens and a landing correction lens, and a spherical shadow mask linearly arranged through a bridge in the Y-axis direction. The color is formed by irradiating the inner surface of the spherical panel through the slot-shaped through holes, and forming a stripe-shaped phosphor layer or a light-absorbing layer in the array direction of the slot-shaped through holes on the inner surface of the panel. In an exposure apparatus for forming a fluorescent screen of a picture tube, when the central axis of the negative meniscus lens is the Z axis and the axis orthogonal to this Z axis and the Y axis is the X axis, the YZ plane including the Y axis and the Z axis and this
The curvature of the line of intersection between the YZ plane parallel to the YZ plane and the outer surface of the negative meniscus lens is made larger at the periphery than at the top of this line of intersection and the YZ plane and the YZ plane and the inner surface of the negative meniscus lens are The curvature of the line of intersection is made smaller in the peripheral portion than at the top of the line of intersection and the meandering and constriction of the stripes formed on the inner surface of the panel are improved.

[Embodiment of the Invention] Next, an embodiment of the invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of an exposure apparatus. That is, in the exposure apparatus, the upper end surface (21) of the frame (20) is used as a mounting portion for the panel (5), and the panel (5) having the shadow mask (8) attached thereto is positioned and mounted. It has become. Panel (5) inside the frame (20)
Toward the light source (3), negative meniscus lens (22),
A landing correction lens (6), a light distribution correction filter (7), etc. are arranged on a support (not shown). Among these configurations, the structures and operations of the landing correction lens (6) and the light distribution correction filter (7) are known, and thus detailed description thereof will be omitted. Further, the light source (3) has a long and narrow linear shape, and its longitudinal direction is linearly arranged through the bridge of the shadow mask (8) attached to the panel (5) positioned on the mounting portion. It is provided so as to coincide with the arrangement direction of the slot-shaped through holes.

The negative meniscus lens (22) has the shape shown in FIGS. 2 (A) and 2 (B). That is, the axis passing through the center of the lens (22) is the Z axis, the longitudinal direction of the long light source (3) is the Y axis,
When the axis orthogonal to the Y-axis and the Z-axis is defined as the X-axis, the curvature of the line of intersection between the outer surface of the negative meniscus lens (22) and the YZ plane including the Y-axis is small near the top (23) and large at the periphery. Has become. This also applies to the YZ parallel plane parallel to the YZ plane. On the other hand, the curvature of the inner surface of the negative meniscus lens (22) and the YZ plane and the YZ parallel plane is smaller in the peripheral portion than in the vicinity of the apex portion (23). This shape is, for example, the shape of the line of intersection between the YZ plane and the YZ parallel plane and the outer surface of the negative meniscus lens (22) is an ellipse having a short axis on the XZ plane including the X axis and the Z axis, and the line of intersection with the inner surface. It can be obtained by setting the shape of to a parabola.

The outer surface and the inner surface of such a negative meniscus lens (22) do not have rotational symmetry unlike the outer surface and the inner surface of the conventional negative meniscus lens (4).

Using the exposure apparatus equipped with the negative meniscus lens (22) as described above, the spherical light source (3) passes through the slot-shaped through hole of the spherical shadow mask (8) to form the spherical panel (5). By irradiating the inner surface with light, it is possible to form a stripe having neither meandering nor constriction for the following reason.

That is, regarding the meandering of the stripe (2) formed on the inner surface of the panel (5), it corresponds to the curvature of the shadow mask (8) and the panel (5) as in the exposure apparatus using the conventional negative meniscus lens (4). Then, the projection of the long light source (3) onto the inner surface of the panel (5) is rotated.
In this case, since the meandering of the stripe (2) is formed around the corner as described above, the shape of the negative meniscus lens (22) corresponding to this part may be optimized.

On the other hand, regarding the constriction of the stripe (2) formed on the inner surface of the panel (5), the negative meniscus lens (22)
The curvature of the line of intersection with the outer surface and the YZ plane, and with the YZ parallel plane is small near the apex (23) of this line of intersection and is large in the area corresponding to the exposure on the peripheral side of the long side of the panel (5). At the same time, the curvature of the line of intersection between the inner surface and each YZ parallel plane is large in the vicinity of the apex (23) of this line of intersection and is small in the region corresponding to the exposure on the long side peripheral portion of the panel (5). By the way, the negative meniscus lens has a concave lens action as a whole to reduce the image, but the outer surface has a convex lens action to enlarge the image, and the inner surface has a concave lens action to reduce the image. Therefore, the negative meniscus lens (22) of the embodiment
If you use, the top (23) as shown in Figure 3 (A), (B)
In the vicinity, since the convex lens action in the direction along the Y-axis is weak on the outer surface and the concave lens action is strong on the inner surface, the reduction ratio of the image (25) of the long light source (3) becomes large. On the other hand, in the region corresponding to the peripheral side of the long side of the panel (5), the convex lens action in the direction along the Y-axis is strong on the outer surface and the concave lens action is weak on the inner surface, so that the reduction ratio of the image (26) of the long light source (3) is small. Becomes smaller. Therefore, the length of the long light source (3) is apparently different in the vicinity of the top (23) by the negative meniscus lens (22) and in the area corresponding to the long side of the panel (5), and the latter, that is, the panel (5). ) Is longer on the long side.

That is, the outer surface and inner surface of the negative meniscus lens (22) and the YZ
By balancing the curvature of the intersecting line between the plane and the YZ parallel plane in the area near the apex (23) and in the area corresponding to the long side peripheral portion of the panel (5), the stripes (2) are set to the optimum light source lengths. The neck can be corrected.

By changing the shape of both the outer surface and the inner surface of the negative meniscus lens (22) in this way, it occurs when the change in the curvature of each cross section along the Y axis that occurs when one of the outer surface or the inner surface is changed is increased. Difficulty in designing and manufacturing due to a large change from the spherical surface can be eliminated, and it is possible to prevent the image distortion caused by increasing the change in curvature and the difficulty in correcting the meandering of the stripe (2) due to this distortion. .

As a specific example, the shape of the line of intersection between the negative meniscus lens and the YZ plane and the YZ parallel plane is 38 mm for the outer surface and the inner surface, respectively.
mm, 26 mm circle, An ellipse with a minor axis on the Z axis (however, A = 5, B = 28)
When the inner surface is changed to a parabola of Z = -bY ² (however, b = 2.06 × 10 ^-2 ), the ratio of the apparent light source lengths of the central part and the peripheral part of the intersecting line is 21% in the color picture tube. From 1: 0.8
It became 1: 1 and the constriction of the stripe near the intersection of the YZ plane and the inner surface of the panel was completely improved. Furthermore, if the shape of the line of intersection between the negative meniscus lens outer surface and the YZ parallel plane is an ellipse with a minor axis on the XZ plane in the same way, and the shape of the line of intersection between the inner surface and the YZ parallel plane is a parabola, then stripes are displayed on the entire screen. The constriction has been improved.

〔The invention's effect〕

As described above, according to the present invention, the fluorescent screen of the color picture tube which can correct both the meandering and the constriction of the stripe formed on the inner surface of the panel by partially changing the shape of the negative meniscus lens is formed. It is possible to provide an exposure apparatus for use.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an embodiment of an exposure apparatus for forming a fluorescent screen of a color picture tube according to the present invention, FIG. 2 (A) is a plan view of the negative meniscus lens of FIG. 1, and FIG. ) Is a sectional view taken along the Y-axis in FIG. 2A, FIGS. 3A and 3B are explanatory views showing the action of the negative meniscus lens, and FIG. 4 shows the meandering of stripes formed on the inner surface of the panel. FIG. 5 is a schematic explanatory view of an example of a conventional exposure apparatus for forming a fluorescent screen of a color picture tube, FIG. 6 (A) is a plan view of the negative meniscus lens of FIG. 5, and FIG. ) Is a cross-sectional view taken along the X-axis of FIG. 6 (A), FIG. 7 is an explanatory view showing the relationship between the long light source, the shadow mask and the inner surface of the panel, and FIG. 8 is an illustration showing the constriction of stripes formed on the inner surface of the panel. It is a figure. 2 …… stripes, 3 …… light source 4,22 …… negative meniscus lens, 5 …… panel 8 …… shadow mask, 10 …… through hole 11 …… bridge

Claims (4)

[Claims] 1. A spherical shape linearly arranged through a bridge in the Y-axis direction by sequentially correcting the trajectory of light emitted from an elongated long light source along the Y-axis by a negative meniscus lens and a landing correction lens. Irradiation to the inner surface of the spherical panel through the slot-shaped through holes of the shadow mask, and the fluorescent surface of the color picture tube is formed so that stripes are formed on the inner surface of the panel in the array direction of the slot-shaped through holes. In the exposure apparatus for use, when the central axis of the negative meniscus lens is the Z axis and the axis orthogonal to the Z axis and the Y axis is the X axis, the YZ plane including the Y axis and the Z axis and the YZ plane are The curvature of the line of intersection between the parallel YZ parallel plane and the outer surface of the negative meniscus lens becomes larger in the peripheral portion than the top of this line of intersection, and also the YZ plane and the YZ parallel plane and the inner surface of the negative meniscus lens. An exposure apparatus for forming a fluorescent screen of a color picture tube, wherein the curvature of the intersection line is smaller in the peripheral portion than in the top portion of the intersection line. 2. The shape of a line of intersection between the outer surface of the negative meniscus lens and the YZ plane and the YZ parallel plane is an ellipse having a short axis on the XZ plane including the X axis and the Z axis. An exposure device for forming a fluorescent screen of a color picture tube according to claim 1. 3. The exposure for forming a fluorescent screen of a color picture tube according to claim 1, wherein the shape of the line of intersection between the inner surface of the negative meniscus lens and the YZ plane and the YZ parallel plane is a parabola. apparatus. 4. The shape of a line of intersection between the outer surface of the negative meniscus lens and the YZ plane and the YZ parallel plane is an ellipse having a short axis on the XZ plane, and the inner surface of the negative meniscus lens and the YZ plane and the YZ plane. The exposure apparatus for forming a fluorescent screen of a color picture tube according to claim 1, wherein the shape of the line of intersection with the parallel plane is a parabola.