JPH034425A - Exposure apparatus - Google Patents

Abstract

PURPOSE:To perform the light source movement necessary for forming a phosphor surface having favorable landing characteristic with equivalent light locus change with an optics with a high accuracy by moving the optics to move the light locus synchronously with the movement of a shutter. CONSTITUTION:A compensation lens 20 is disposed between a shutter 16 and an exposure light source 13. A light path changing optics 26 comprising a flat glass plate is disposed at a position between the compensation lens 20 and the exposure light source 13 and near the light source 13. The locus of the light from the light source 13 may be changed with a good accuracy equivalently as if the exposure light source 13 has moved apparently by the orbiting of the light path changing optics 26. Exposure is made by synchronizing the orbiting of the light path changing optics 26 with the movement of the shutter 16. This enables the formation of a phosphor surface of favorable landing characteristic over the entire inner surface of the panel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an exposure apparatus used for forming a phosphor screen of a color picture tube.

(Conventional technology) Generally, a color picture tube is as shown in Fig. 7.

It has an envelope consisting of a panel ■ and a funnel ■, and a fluorescent screen (to) is formed on the inner surface of the panel, facing a shadow mask ■ equipped with a large number of through holes attached to the inside of the panel ■. ing. This phosphor screen consists of a three-color phosphor layer in the form of stripes or dots that emit light in blue, green, and red. Furthermore, in order to improve the contrast of one screen, a non-luminous layer mainly composed of carbon or the like is provided in the gaps between the three-color phosphor layers, resulting in a so-called black stripe type or black matrix type.

The image is displayed on this phosphor screen (A) using three electron beams (6B), (6G), (6G) emitted from the electron gun ■.
R) is deflected horizontally and vertically by the magnetic field formed by the deflection yoke attached to the outside of the funnel.
This is done by scanning the fluorescent screen (a). Therefore, in order to display an image with good color purity on this phosphor screen (A), as shown in FIG.
For each electron beam (6B) that passed through the hole ■
, (6G) and (6R) correspond to the phosphor layer (9
B).

It is necessary to correctly fire at (9G) and (9R). In particular, the positions of the three-color phosphor layers (9B), (9G), (9R) with respect to the through hole 0 of the shadow mask ■ are the electron beams (6B), (6G), (
The apparent upper emission position (deflection center) changes according to the deflection angle of the phosphor layer (9R).
B), (9G), (9R) with electron beam (6B
), (6G), and (6R) to collide correctly, 6 panels O) At each point on the inner surface, apply a three-color phosphor layer (9B) to the through hole 0 of the shadow mask ■.
.

It is necessary to change the positions of (9G) and (9R)9
In other words, as shown in Fig. 9 for the center beam (6G) of three electron beams arranged in a row emitted from an in-line electron gun, this electron beam (6G) has a uniform magnetic field strength of the deflection yoke. Then, the deflection magnetic field (11
), and after exiting the deflection magnetic field (11,), it moves straight, passes through the hole (c) in the shadow mask (2), and hits the phosphor layer (9G). Therefore, the apparent impact position of the electron beam (6G) is the upper impact position, that is, the direct I! The position of the deflection center (F) where the extension line of the trajectory intersects with the tube axis (X) changes according to the deflection angle γ. In other words, when the deflection angle is γ, it has a γ-ΔP characteristic in which it moves toward the ΔP phosphor screen 0) side compared to when the deflection angle is zero.

On the other hand, conventionally, phosphor screens are made by applying a phosphor slurry mainly composed of phosphor and photosensitive resin to the inner surface of the panel, drying it, and then exposing the film to light through a shadow mask, as shown in Figure 10. After baking a pattern corresponding to the hole in the shadow mask.

A phosphor layer of any one color is formed by developing and removing an unexposed area (3), and each of these steps is repeated for three color phosphor layers. In particular, for a phosphor screen having a non-emissive layer, prior to forming the three-color phosphor layer, a photosensitive resin is applied, and a similar method is applied to the formation position of the three-color phosphor layer to correspond to the hole in the shadow mask. After forming a photosensitive resin pattern, a non-luminescent paint is applied, and then this non-luminescent paint is peeled off together with the photosensitive resin pattern to form a non-luminescent layer with voids at the positions where the three-color phosphor layer is formed. form. Manufactured by two.

Regardless of whether this is a phosphor layer or a non-emissive layer.

Since the film formed on the inner surface of the panel is exposed to light in a straight line, the exposure process is performed as shown in FIG. 11.

A panel ■ equipped with a shadow mask ■ and an exposure light source (13
), an exposure device is used which is provided with a correction lens (15) that approximates the trajectory of the light (14) emitted from the light source (13) to the trajectory of the electron beam.

Note that (16) is a shutter for partially exposing the film, and (17) is an aperture that controls the exposure area.

A spherical lens was once used as such a correction lens (15), but as the structure of color picture tubes became more complex, 1. It is no longer possible to correct the γ-Δp characteristic with a simple lens, and aspheric lenses with complex surface shapes are now used.

The surface shape of this aspherical lens is expressed by the orthogonal coordinates (X, Y, Z axes) with the origin at the center of the bottom surface of the lens, and the surface height at an arbitrary point, or x = f (yt z)
Represented by CD. Also, in polar coordinates (r+θ), χ=f (r, θ) ■r=νy
2 + z2 θ= tan-'' (y/z), and for -convergence, for example, the 0 expression is represented by a polynomial.

Design of a correction lens using such a formula involves tracking how the light emitted from the exposure light source changes with respect to the amount of change in each coefficient aiJ over the entire surface of the phosphor screen. It is designed so that the error from the incident position of the electron beam is less than a certain value (usually 10 microns). However, even with this method of design, it is relatively easy to reduce the error at a limited number of points on the correction lens, but the coefficient aiJ can be Even if you set the coefficient a
Since iJ generally acts to increase the error at most other points, it is extremely difficult to design so that the error is less than a desired value at all points on the phosphor screen. Even if a high-performance, ultra-high-speed computer is used, not only is the design time-consuming, but in many cases, changing the coefficient aiJ requires judgment based on extensive experience.

Therefore, in color picture tubes with complex deflection magnetic fields, such as 110-degree deflection color picture tubes with large deflection angles and large color picture tubes, it takes a lot of time to design the correction lens, and it is difficult to obtain correction lenses that have the desired characteristics. It cannot be made into a lens.

As another method of designing correction lenses,
In Publication No. 83 and Japanese Patent Publication No. 49-22770, the first
As shown in FIG. 2, a method is shown in which the correction lens (15) is divided into a plurality of parts and the slope of the surface of each part is determined. Such a method allows the trajectory of light during exposure to match the trajectory of the electron beam with high accuracy for each divided portion, and it is possible to obtain a correction lens that satisfies the γ-Δp characteristic. However, such a correction lens (15) has a step (18
).

In particular, for black stripe type or black matrix type phosphor screens in which a non-emissive layer is provided between the three-color phosphor layers, unevenness occurs on the phosphor screen due to uneven light intensity due to the step (18). Easy methods to solve this problem include a method of swinging the correction lens (15) during exposure and a method of shielding the stepped portion from light.

In neither case can the unevenness of the phosphor screen be made to a sufficiently satisfactory quality.

(Problem to be Solved by the Invention) As mentioned above, the phosphor screen of a color picture tube is created by printing a pattern corresponding to the through holes of the shadow mask onto a coating of phosphor slurry or photosensitive resin formed on the inner surface of the panel. In this case, a correction lens is used to approximate the trajectory of light emitted from the exposure light source to the trajectory of the electron beam deflected by the magnetic field formed by the deflection yoke. However, the surface shape of this correction lens is complex, and it is difficult to design it so that good landing can be obtained at all points on the phosphor screen, especially for wide deflection angle color picture tubes and large color picture tubes. The desired correction lens has not been obtained for the phosphor screen of a color picture tube, which has a complex deflection magnetic field.

As a result of various investigations into the causes, the inventor discovered that the major cause of difficulty in designing a correction lens is the difference between the γ-Δp characteristics of horizontal deflection and the γ-Δp characteristics of vertical deflection of electron beams. I found a headline.

That is, the surface height X at an arbitrary point P of the correction lens (15) shown in FIG. 13 is not determined only by the point P, but is determined as the sum of the inclinations from the central axis of the correction lens (15), and generally, Since the surfaces on the Z-axis and the Y-axis completely satisfy each landing characteristic, the surface height X at an arbitrary point P is calculated from 21 on the Z-axis and yi on the Y-axis Only when the starting case and the starting case match, both the Y direction and the Z direction are completely corrected. However, as shown in Figure 4(a),
Let the surface height at 21 on the Z axis be x(o+zJ).

When the surface height of point P is determined from this 21 in the Y direction, the surface height of one point P becomes x2 on the curve (19a). On the other hand, as shown in (b), the surface height at yl on the Y axis is x(ytto), and a point P is located in two directions from y8.
As the surface height of one point P is determined, the surface height of one point P becomes a curve (
19b) The above X becomes, and the correction from the Z axis to the Y direction,
The correction from the Y-axis to the Z-direction does not necessarily match; in fact, it often does not match. This is due to the difference between the center of deflection when deflecting the electron beam in the horizontal direction and the center of deflection when deflecting the electron beam in the vertical direction. It has been found that no matter what curved surface display formula is used, it is impossible to design a correction lens that satisfactorily corrects landing errors at all points on the phosphor screen.

This kind of problem is not so much of a problem with color picture tubes, such as black stripe type, which have a vertically extending stripe-like phosphor screen and do not require consideration of vertical landing. This has a large effect on color picture tubes with dot-shaped layers, especially wide-polar color picture tubes with a polarization of 110° and large color picture tubes.

This invention was made in view of the above problems, and
An object of the present invention is to construct an exposure device that can easily form a phosphor screen that cannot be satisfactorily corrected with a conventional correction lens.

[Structure of the Invention] (Means for Solving the Problems) In an exposure device used for forming a phosphor screen of a color picture tube, an exposure area is formed on a film of photosensitive resin or phosphor slurry formed on the inner surface of the panel. An optical system is provided to change the trajectory of light from the light source so that the light source that apparently exposes the coating moves in synchronization with the movement of the regulating shutter, and is synchronized with the movement of the shutter using a drive device. The optical system was configured to move so as to change the trajectory of the light.

(Function) In order to improve the landing characteristics over the entire phosphor screen of a color picture tube, it is necessary to synchronize the movement of the shutter so that the center of horizontal deflection and the center of vertical deflection based on the γ-Δp characteristic almost coincide. It is a good idea to move the light source by
In this case, the movement of the light source is very small, and it is fixed to mechanically move the light source itself with high precision, but by providing an optical system that changes the trajectory of the light from the light source as described above,
If you move this optical system in synchronization with the movement of the shutter so that the light source moves, you can equivalently move the light source with high precision by changing the trajectory of the light passing through the optical system. can.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

As shown in FIGS. 3 and 4, a correction lens (20)
The exposure light! (13) is the point Xo co on the X axis.

0). Further, it is assumed that the inner surface of the panel ω is a plane parallel to the YZ plane passing through xl on the X axis. In this case, the light emitted from the exposure light g (13) is
), it is refracted by the correction lens (20), passes through the aperture (17) of the shutter (16) and the through hole of the shadow mask (2), and reaches y on the inner surface of the panel (2). Then, a region (22) corresponding to the aperture (17) of the shutter (16) is provided.
). Here, when the electron beam incident on -V> is deflected so as to be incident on yl by the vertical deflection magnetic field of the deflection device, the deflection center is from the deflection center of the horizontal deflection magnetic field that deflects the electron beam so that it is incident on the same yl. , Assuming that only X4 is on the panel O) side, in order to project the light to yi through the same trajectory as the electron beam, the solid line (23)
As shown in , the exposure light source (13) is
In other words, the shutter (16) needs to move by y2 on the Z-Y plane passing through xo in the opposite direction to the shutter (16) that moves in the Y-axis direction (x→y1 direction). Namely.

When the γ-ΔP characteristic of the vertical deflection magnetic field is γ=γ, Δp=
When x4, the relationship shown as y:x41 tanγ1 holds true, and it is sufficient to move the exposure light source (13) by y2 in the opposite direction to the moving direction of the shutter (16).

Therefore, in order to move the exposure light source (3) so as to obtain good landing characteristics over the entire surface of the phosphor screen, the following procedure may be used.

For example, if we focus on the landing characteristics near the straight line (Z-axis) shown by z=z in FIG. 3, the γ-ΔP characteristic in the Z-axis direction at y=o is γ=γ2 and Δp=x.

If the γ-ΔP characteristic in the Z-axis direction at '/"yl is γ=γ, ΔP=Xa, and X,>X, then ΔP when γ=γ1 is ΔP""Xs (Xs Xi), and the amount of movement of the exposure light source (13) at this time is y
4 is '/*' (X4 (Xi Xi)) tanγ
It becomes 1.

The method of determining this γ-Δp characteristic varies depending on which part of the phosphor screen 2 is focused on the landing characteristic, but in any case, the amount of movement y, Il of the exposure light source (13).

Let Δp of the γ-Δp characteristic be x8.

lm=X59tanγ1 becomes.

FIG. 1 shows an exposure apparatus that carries out the above exposure method. This exposure apparatus consists of a support stand (25
), and an exposure light source (13
) is installed. As this exposure light i1 [(13)1, a water-cooled or air-cooled ultra-high pressure mercury lamp is usually used, but there are also laser beams or those that emit laser beams through a light guide body such as an optical fiber. Can be used. In addition, a Z
A shutter (16) in which a long opening (17) is formed in the axial direction (horizontal direction) is arranged. A correction lens (2o) is disposed between this shutter (16) and the exposure light source (13), and furthermore, this correction lens (20)
Between the exposure light source (13) and the exposure light source (13), the exposure light! Optical path changing optical system (26) consisting of a flat glass plate close to (13)
is located.

A rack (28) is attached to the shutter (16) to move it in the Y-axis direction (vertical direction).

A pinion (29) meshing with this rack (28) is rotated forward and backward by a motor (30) via a belt (31), thereby reciprocating the shutter (16) in the Y direction. In addition, a pulley (32) is attached to the center of the optical path changing optical system (26), and a belt (
33), the motor (30) is driven to move the arrow (3) in synchronization with the reciprocating movement of the shutter (16) in the Y direction.
It is designed to oscillate as shown in 4).

In FIG. 1, GE is a shadow mask installed on panel (2), and (35) is a film of photosensitive resin or phosphor slurry coated on panel (2).

By the way, in order to form a phosphor screen with good landing characteristics as described above, the exposure area is limited and the deflection center of the horizontal deflection and the deflection center of the overlapped deflection are determined for each exposure area based on the γ-Δp characteristic. Exposure light source (13
) is required, but if the exposure apparatus is configured as described above, the optical path changing optical system (26)
By the rocking of the optical path changing optical system (26), the trajectory of the light from the light source (13) can be changed with high accuracy, as if the ball exposure light source (13) had moved. By performing partial exposure in synchronization with the movement of the shutter (16), a phosphor screen with good landing characteristics can be formed over the entire inner surface of the panel.

For example, for a 25-inch 100-degree deflection color picture tube, the exposure light source (
The amount of movement 13) is about 0.2■, and the light source (13) is moved minutely by precisely synchronizing this minute amount of movement with the movement of the shutter (16).

It is extremely difficult to mechanically perform such minute movement of the light 111 (13) itself with high precision. but,
When using an optical path changing optical system (26) made of a flat glass plate, in the case of a 25-inch 100-degree deflection color picture tube, the dimensions of each part of the exposure device are as follows: distance
63.15 ■ Distance from light source (13) to shutter (16) 215.05 m Distance from light 1 (13) to shadow mask ■ 326.05 m Distance from light source (13) to panel ■ Inner surface 33
6.35m correction lens (center thickness of 2
It is 81111. Therefore, if the optical path changing optical system (26) is made of thin flat glass and the glass refractive index n is 1.5168, the optical path changing optical system (26) has a small inclination as shown in FIG. In case, A
Therefore, the optical path changing optical system (2
If the plate thickness of the light source (13) is t, the incident angle θ and the refraction angle of the light incident on the optical path changing optical system (26) are 02, then the light source (13)
The apparent upward movement amount is X.

x=tsin(θ1-θ2) θ,=sin-''(ginθ1X 1.5168)si
nθ1−sinθ, = sinθ, −sin (sin
-θX 1.5168) = sinθ1-1.5168
sin θ.

-1,5168 sin θ1=x/l Therefore, if the thickness t of the flat glass is 10 cm.

Light i! [i[(13) for a movement amount of 0.2 gardens.

1.5168 sin θ1=0.02 θ,=-2,2゜ becomes. In addition, a patent characterized by the thickness t of flat glass. -1゜5168 sinθ=0.2 θ、、＝　−22゜8＠ becomes.

In other words, the glass plate thickness t of the optical path changing optical system (26).

For example, if it is 1m, the maximum movement of the shutter (16) is
It is sufficient to tilt the shutter (16
) can be tilted with high precision in synchronization with the movement of the

In addition, according to the above exposure apparatus, the surface height at an arbitrary point of the correction lens can be determined from the value obtained from the Y axis and the Y
There is no need to perform a compromise design that matches the value obtained from the Y axis. A unique phosphor screen can be formed using this method.

In the above embodiment, the optical path changing optical system of the exposure apparatus was constructed of a flat glass plate, but this optical path changing optical system was
As shown in the figure, it may be formed into a spherical shape with a concave surface on the exposure light source (13) side.

Further, as the swinging mechanism of the optical path changing optical system, in addition to the mechanism using a belt, a pulley, etc. in the above embodiment, other mechanisms such as a crank mechanism (37) shown in FIG. 6 may be used, especially this swinging mechanism. If it is configured with a crank mechanism (37), the swing angle can be easily adjusted by changing the position of its attachment to the optical path changing optical system (26).

Furthermore, in the above embodiment, a case was described in which the shutter was moved in the Y-axis direction, but this movement of the shutter was performed in the Z-axis direction.
It may be in the axial direction.

Also, regarding the correction lens to be used, x=f (y,
z) Not only can the surface shape be expressed by a single formula, but also a correction lens that can be expressed by multiple formulas, or a correction lens that is divided into multiple blocks and has a step on the surface.

Regarding the γ-ΔP characteristic, if the trajectory of the light does not intersect with the X-axis, the intersection angle when projected onto the Y-X plane or the 2-X plane may be used.

[Effects of the Invention] The light source that exposes the film appears to move in synchronization with the movement of the shutter that regulates the exposure area for the film of photosensitive resin or phosphor slurry formed on the inner surface of the panel. An optical system is installed to change the trajectory of light from the
The optical system is configured to be moved by a driving device so that the trajectory of the light changes in synchronization with the movement of the shutter.

The movement of the light source required to form a phosphor screen with good landing characteristics can be performed with high precision by equivalently changing the trajectory of the light using the optical system.

[Brief explanation of drawings]

Figures 1 to 6 are detailed explanatory diagrams of this invention.
The figure is a configuration diagram of an exposure device used to form the phosphor screen of a color picture tube, which is an example of the same. Figure 2 is a diagram for explaining the optical path changing optical system. FIG. 4 is a perspective view for explaining the principle of the exposure method; FIG. 4 is an X-Z plan view for explaining the principle of the exposure method; FIG. 5 is a diagram showing another shape of the optical path changing optical system; The figure shows another swinging mechanism of the optical path changing optical system, Figures 7 to 11 are explanatory diagrams of the prior art, and Figure 7 is a diagram showing the configuration of a color picture tube.
The figure is a diagram to explain the landing of three electron beams on the three-color phosphor layer of the phosphor screen, Figure 9 is a diagram to explain the movement of the deflection center due to the deflection magnetic field, and Figure 10 is a diagram to explain the manufacturing method of the phosphor screen. A block diagram for explanation; FIG. 11 is a configuration diagram of a conventional exposure apparatus; FIGS. 12(a) and (b) are a plan view and a cross-sectional view of a correction lens divided into multiple parts, respectively; FIG. 13 is a block diagram of a conventional exposure apparatus; Figures 14(a) and 14(b) are diagrams for explaining the design method of the correction lens, respectively.
FIG. 7 is a diagram showing the surface shape of the Z-P cross section of the correction lens shown in the figure, and a diagram showing the surface shape of the Y-P cross section. ]...Panel 3...Shadow mask 13
...Exposure light source 16...Shutter・-17・
...Aperture 20...Correction lens 26...
Optical path changing optical system 28...Rack 29...Pinion 30...Motor 31...Belt 32...
pulley

Claims (1)

[Claims] A light source that exposes a film of photosensitive resin or phosphor slurry formed on the inner surface of the panel through a shadow mask, a movable shutter that regulates the exposure area for the film, and a light source that synchronizes with the movement of the shutter. an optical system for changing the trajectory of the light from the light source so that the light appears to move; and a driving device for moving the optical system so as to change the trajectory of the light in synchronization with the movement of the shutter. An exposure device characterized by: