JPS58133746A - Image transmission face plate - Google Patents

Abstract

PURPOSE:To obtain an image with a very good contrast and high clearness having almost no faded or blurred light spot consisting the image by providing illuminants such as phosphor, and the like on one side of an image transmission face plate corresponding to each lens part in a cathode-ray tube face plate. CONSTITUTION:A masked substrate 10 is floated in liquid salt 13 containing ions of thallium (Tl) and cesium (Cs) largely contributing to increase a refractive index while keeping a lens formative face downward and the upper side (a light absorbing layer formative face) thereof is surrounded liquidtight by side plates 14 while the inside thereof is filled with salt 15 containing glass colored ions such as Ag, Cu and Au ions, for instance, silver sulfate liquid salt. In this way, lens parts with crescent sections having refractive index distribution corresponding to the distribution of thallium ion concentration are formedon a glass face on the anode side. Further at the same time, Ag ions are doped to substrate glass at the part not covered by the mask 12 on the other surface of the substrate 10. Thereby the sectional shape 4A of the lens parts becomes nearly semicircular thus improving the refractive index distribution thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image transmission face plate which is suitable for use as a cathode ray tube face plate and is capable of obtaining very clear and high-intensity images. In general, cathode ray tubes are made of fairly thick glass in order to withstand high vacuum conditions. Because of this, the light emitted from the phosphor provided on the inner surface of the 7-Ace plate glass is diffused while passing through the No-Ace plate glass, and the light from adjacent phosphors overlaps each other, so the image is not sufficient for the entire image. There is a problem in that it is not possible to obtain sufficient clarity.

To solve this problem, there is a cathode ray tube that uses a fiber plate, which is made by bundling and fusing many optical fibers in parallel and finishing it into a flat plate, as part of the front panel, and is mainly used for sending and receiving facsimiles. However, in the fiber plate described above, the amount of light that can pass through the core of each optical fiber is relatively small compared to the amount of light received over the entire plate area, and sufficient brightness cannot be obtained. Very few air bubbles at the fusion bonding interface between optical fibers, M type or 1
．． However, it is technically difficult to manufacture because it adversely affects the high vacuum degree and high voltage withstand characteristics, and for this reason, it is extremely difficult to use the above fiber plate in a relatively large-area cathode ray tube 7A such as a television picture tube. 10) There is a problem that it is not practical because it is expensive.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a novel image-transmitting face plate suitable for use as a cathode ray tube face plate, which can provide clear, high-intensity images and can be manufactured at low cost.

In the present invention, a microlens portion having a substantially circular cross section and having a refractive index greater than that of the substrate is located approximately at the center of the thickness of a generally parallel plane transparent substrate made of glass or synthetic resin. The image transmitting face plate of the invention is formed by arranging and integrally forming a large number of light emitters such as phosphors on one side of the base plate, and through these individual lens portions at least within the desired plane of the base plate. By providing it in correspondence with the lens part, the light diffused and emitted from the light emitter during electron beam irradiation, etc. is focused at the lens part within the thickness of the substrate, and is formed into dots on the opposite side of the board according to the shape of the lens part. Alternatively, it forms a linear image. In this way, the light that exits from a small area on one surface and enters the face plate is efficiently focused on the other surface 1 without being diffused. Since the light is focused on the image, it is possible to obtain a highly clear image with very good contrast and almost no blurring of light spots or color blurring that would otherwise affect the image.

In addition, since it does not have a bonding interface that runs through the thickness of the face plate unlike a fiber plate, a highly reliable product with high strength and no fear of vacuum leakage can be obtained.

Further, as will be described later, it can be easily manufactured at low cost using well-known patterning techniques such as photolithography and glass ion exchange techniques.

The product of the present invention can be used in a wide range of image transmission applications, such as general display devices and facsimile transmission/reception devices, in addition to the face plates of cathode ray tubes.

In carrying out the present invention, the lens portions may have a substantially spherical shape and be arranged in one or more rows along the vertical and/or horizontal directions of the substrate.

Alternatively, the lens portion can be formed in a line shape with the same cross-sectional shape continuing in the vertical or horizontal direction of the substrate.

The refractive index of the lens part needs to be higher than that of the substrate, but even if the refractive index within the lens part is uniform, it has a maximum value at the center and gradually decreases toward the outer periphery. It may have a refractive index distribution of square approximation.

As described above, the image transmission face plate according to the present invention is capable of obtaining high-definition images even as it is, but a light absorption layer is provided on one side of the substrate over the entire surface except for the area near the imaging area formed by the lens part. By providing a filter to block unnecessary light that does not contribute to image formation passing through the substrate, it is possible to further improve the contrast.

The present invention will be described in detail below with reference to embodiments shown in the drawings.

As shown in the enlarged view in Fig. 1, the face plate l is fused to the front surface of the transparent substrate 3, and a lens portion q with a circular cross section is parallel to the plane in the center of the transparent substrate 3 in the thickness direction. They are arranged adjacent to each other in the direction.

Inside the lens part, the refractive index is lower than the refractive index N1 of the substrate, and when the refractive index at the center is Ho, the refractive index N (r) at a distance r from the center is approximately N(r) −No (/-/ /JAr2) ・−・−・
- It has the distribution expressed by (1).

In addition, although the lens portion is circular in the vertical section of the face plate l, it is formed in a line shape in the horizontal direction so that the same cross-sectional shape and the same refractive index distribution continue, as shown in the perspective view in Fig. 3. 0 With the above structure, when the phosphor j provided on the inner surface /A of the face plate l is irradiated with an electron beam and emits light, the light l1It enters the face plate l while being diffused, but due to the lens portion D, it is It is focused to form an image 7 on the outer surface IB.

As shown in Fig. 1, the outer surface /B of the face plate l has a slit-shaped tip portion g at the imaging position of each lens portion da.
The remaining areas are covered with a light-absorbing colored layer 9 provided integrally within the substrate glass.

To give a typical numerical example, the thickness of the transparent substrate 3 is WOm4.
1111m + diameter of lens part d-200μ, width W of phosphor, -/-〇μ, arrangement interval of phosphor 11-200μ
, the width W2-/koOμ of the light-transmitting portion l on the imaging surface side, and the width w3-toμ of the light-absorbing layer 9 between the light-transmitting portions tr-r.

Next, a preferred example of a method for manufacturing the above-mentioned image transmission face plate will be described. First, a transparent substrate 10 having a thickness half the required thickness WO of the face plate is made of alkali-containing glass.

A mask for preventing ion movement that has a pattern on one side of the substrate IO that is a negative inversion of the plane pattern of the lens area.
This mask // is made of titanium, for example with a thickness of about -μ, and is deposited by radio-frequency sputtering.

Further, on the other surface of the substrate 10, there is provided a mask for preventing ion movement similar to that described above, which has a pattern that is a negative inversion of the pattern of the light absorption layer 9.

For patterning the masks // and /-, well-known photolithography techniques can be used as they are.

Next, the masked substrate 10 is placed with the lens forming surface facing downward.
Thallium (Tl) makes a large contribution to increasing the refractive index.

Floating on molten salt /3 containing ions such as cesium (C8), and surrounding the upper surface side (light absorption layer forming surface) with side plate /l
It is surrounded in a liquid-tight manner and filled with Agt (salt containing glass coloring ions such as Au ions), for example, molten silver nitrate salt.

Next is Isho Fusio i3. Electrode plates #A and 74B such as titanium plates were respectively set in the IR, and the temperatures of the molten salts /J and /3 and the glass substrate 10 were maintained at around 60°C.
The treatment is carried out for about 1 hour while applying a DC voltage of approximately 0.5 volts to the electrode 76B in the molten salt on the lens forming side with the electrode 76B in the molten salt being positive and the light absorbing layer forming side being negative.

Through the above treatment, for example, thallium ions in the molten salt/3 diffuse into the glass from the anode side surface of the substrate glass 10, and sodium ions in the glass exit from the cathode side. A development occurs in which silver ions diffuse into the glass from the molten salt lj. This is because the ion diffusion rate in the surface area of the substrate IO is different, and the elution rate of Na ions is linked, resulting in electrical neutralization near the cathode side glass surface. It is considered that the properties are no longer maintained, and as a result, the mug ions contained in the molten salt on the cathode side diffuse in the opposite direction to the direction of the electric field.

As described above, a lens portion having a crescent-shaped cross section and having a refractive index distribution corresponding to the strength distribution of thallium ions is formed on the glass surface on the anode side.

At the same time, mug ions are doped into the substrate glass in a portion of the other surface of the substrate 10 that is not covered with the mask.

After that, the substrate glass 10 is taken out, and after removing the masks ii and i on the surface, it is heated at a temperature of approximately 00° C. for several hours.
Heat treatment is performed for several IO hours. As a result, the cross-sectional shape of the lens portion lm becomes approximately semicircular, and its refractive index distribution becomes close to the above-mentioned equation (1). At the same time, 5g of Ag ion doped layer
By turning into a colloid, it becomes a light absorption layer 9 that blocks scattered light.

Lens plate IO with light absorption layer 9 obtained as above
A and another lens plate 10B having exactly the same configuration as the lens plate described above except that the light absorption layer 9 is not provided are joined together by heat fusion etc. with their lens forming surfaces facing each other. An inventive image-transmitting faceplate can be obtained.

As a method of manufacturing the lens plate 10A with a light absorption layer, in addition to doping colored ions into the substrate glass as in the above embodiment, a light blocking thin film may be attached to the surface of the substrate glass by vapor deposition, sputtering, or the like.

As mentioned above, when the lens part DA is made into a line shape extending in the horizontal direction, the light rays from the phosphor j are focused only within the vertical cross section and are diffused in the horizontal direction as usual. 7. The movement angle in the horizontal direction is much larger than in the horizontal direction, and according to the above structure, when the cathode ray tube surface is viewed from an oblique direction, a portion of the light spot 7 is hidden by the presence of the light absorption layer 9. Since the light is focused in the vertical direction, the brightness is sufficiently high and it is very easy to see.

FIG. 7 shows another embodiment of the present invention.

This example is an image transmission face plate in which the shape of the lens portion l within the thickness of the substrate 3 is approximately spherical, and a large number of lens portions l are arranged in a matrix in the vertical and horizontal directions of the substrate 3, as shown in FIG. It can also be used on cathode ray tube faceplates.

According to the structure of this example, light diffused and emitted from a point light emitting source such as a phosphor provided on one side of the face plate l is focused into a point on the other side of the substrate.

The image transmission face plate with the above structure is manufactured in the same manner as above, with the openings of masks // and /2 being circular instead of slits, and with or without a light absorption layer. can do.

In addition to having a large number of spherical lens parts arranged in a matrix along the vertical and horizontal sides of the substrate, it is also possible to have only one row of spherical lens parts on the face plate of a cathode ray tube used in facsimile transmitting/receiving devices, printers, etc., depending on the application.

Furthermore, the display panel can be constructed by attaching a minute light source such as an LED instead of the fluorescent body j in the embodiment.

[Brief explanation of drawings]

FIG. 7 is a perspective view of a cathode ray tube using the image transmission face plate of the present invention, FIG. 2 is a vertical cross-sectional view of the same essential part, FIG. The figure shows an example of a method for manufacturing the example shown in FIG. 2, and FIG. 1 is a perspective view of a substrate on which a mask is applied. Figure 5 is a vertical cross-sectional view showing the ion exchange process, and Figure 6 is a book in which the lens plate with the light absorption layer obtained in the process of Figure 5 and another lens plate without the light absorption layer are bonded together. FIG. 7 is a longitudinal cross-sectional view showing the process of manufacturing the image transmission face plate of the invention, and FIG. 7 is a front view showing another embodiment of the invention.

Claims (1)

[Scope of Claims] 1) A micro-diaphragm with a substantially circular cross section that has a refractive index greater than that of the transparent substrate and has a refractive index greater than the refractive index of the substrate.
A plurality of lens portions are arranged and integrally formed, and an image of a point light source in one direction of the substrate is formed on the other side of the substrate within at least one cross section through these individual lens portions. Transmission face plate. 2J The lens portion is constructed by joining two transparent plates, each of which has semicircular cross-sectional lens portions arranged in the same arrangement pattern on one side rkI, with their laser formation directions facing each other. An image transmission face plate according to claim 1, characterized in that: 3) The image transmission face plate according to claim 1, wherein the lens portions are spherical and are arranged in large numbers along the vertical and/or horizontal directions of the substrate. 4) The image transmission face plate according to claim 1, wherein the lens portion is formed in a line shape with the same cross-sectional shape continuing in the vertical or horizontal direction of the substrate. 5) The image transmission face plate according to claim 1, wherein the lens portion has a refractive index distribution such that the refractive index is maximum at the center and gradually decreases toward the outer periphery. 2. The image transmission face plate according to claim 1, wherein a light absorption layer is provided on one side of the substrate except in the vicinity of the image formation area by the lens portion. 7) Image transmission face plate b according to claim 1, characterized in that a light emitting source such as a phosphor or an LED is provided on one side of the substrate in correspondence with each lens portion.