JPH06310060A - Fluorescent character display tube - Google Patents

Abstract

PURPOSE:To improve controllability of an electron, and realize a thin and compact type by forming an anode forming base body of a metallic plate having a through-hole, and fixing an anode and phospor inside of the through-hole, fixing a grid to the obverse of the base body, and fixing anode wiring to the reverse of the base body. CONSTITUTION:A through-hole which is large on the obverse and is small on the reverse is formed in a backing plate BP. A recessed place is formed as a cross-sectional shape, and the inside surface is coated with an anode A and phosphor PH. Though a metallic plate is used as a base body, in order to insulate it from the anode A or the like, almost the whole metal surface is coated with a dielectric DL. An inorganic dielectric containing glass is used as coating so that dense coating having high insulating performance becomes possible. Wiring of the anode A is formed on the reverse of the backing plate BP, and a grid electrode GR is formed on the obverse side, respectively by printing. An insulating layer is formed under the grid electrode GR by printing of glass ink. A reverse side small hole is sealed airtightly by sealing glass SG. Though the hole is blocked up by the anode and the wiring, the phosphor, the sealing glass or the like, when a printing technology is applied, the size of not more than 0.4mm is preferable as the minimum width of the hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent display tube.

[0002]

2. Description of the Related Art Recently, thin fluorescent display tubes have been favored. FIG. 1 shows a schematic partial cross section of the structure of a general fluorescent display tube. FG is a front glass plate, BP is a back plate, K is a cathode, A is an anode, GR is a grid, PH is a phosphor, and DL.
Represents a dielectric. Note that those not shown are omitted because they are not directly related to the present invention. Further, the same reference numerals in FIG. 2 below mean the same things.

A spacer is sandwiched between a front glass plate FG and a rear plate BP and airtightly fixed with frit glass to form a vacuum container. Vacuum exhaust is performed from an exhaust hole provided in a spacer or a back plate, and an exhaust pipe connected to the hole is chipped off or sealed with a lid to complete a vacuum container.
A getter is provided in the container to maintain a high vacuum.

A filamentary hot cathode K, which is an electron radiator, is stretched. A field emission cathode may be applied to the substrate. An anode A and its wiring are attached to the back plate, and a phosphor PH is applied to the surface of the anode. Excess wiring and the like are covered with the dielectric DL. The components fixed to the substrate are usually formed by a thick film technique such as screen printing or a thin film technique such as vapor deposition, sputtering or etching. A grid GR made of a mesh-shaped metal plate is installed between the cathode and the anode.

The function of the grid is to extract and accelerate electrons in a wide range regardless of the area of the anode, and when there are many display elements, form a matrix with a plurality of anodes and a grid and drive them in a time division manner. For the electronic controllability and uniformity of the grid, the configuration as shown in FIG. 1 is preferable. However, the following problems occur.

That is, the grid installed in the hollow must be fixed to the substrate or the like. Since it is made of a metal plate, a simple method such as thick film or thin film technology cannot be applied for fixing. With multiple grids, the effort is considerable. Further, since it is bent by the electrostatic force, it cannot be placed too close to the cathode. Therefore, the driving voltage increases as the distance increases, and the high electric field cannot be applied, resulting in low luminance.

Therefore, the following measures are taken. The grid is formed by thick film or thin film technology. Figure 1
It may be formed at a position between the anodes, and it can be formed at the same time as long as it has substantially the same surface as the anode and the same material. Although this method solves the above drawbacks, it has a new problem.

The first is that the electron controllability is poor because it is on the same plane as the anode, and the second is that a fine pattern is required to be formed between the anodes. Since there is an insulating space between the grid pattern and the anode, it is difficult to form the fluorescent pattern with a small space between the phosphors, and the electron beam is likely to be adversely affected by the charges charged in the insulating space. Further, since the anode wiring and the grid cross each other, a multilayer wiring is required, which increases the number of steps. As described above, the conventional technology still has various problems.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems of the prior art and has good electronic controllability.
It is an object of the present invention to provide a thin and compact fluorescent display tube that can form a fine light emitting portion at low cost.

[0010]

The above object of the present invention is achieved by the following fluorescent display tube.

That is, the present invention relates to a fluorescent display tube comprising a cathode which is an electron emitter, a grid for electronic control, and an anode having a phosphor coated on the surface thereof in a vacuum container. Is formed from a metal plate having a large through-hole on the front surface and a small through-hole on the back surface, and substantially the entire surface of the metal plate is coated with a dielectric material containing glass. Inside the through hole, an anode and a phosphor are provided. Is a grid, and anode wiring is fixed to the back surface of the substrate.

[0012]

EXAMPLES The present invention will be described below based on examples.
In addition, general materials and techniques are applied to those not described in the following embodiments.

Embodiment FIG. 2 is a schematic partial sectional view showing an example of the fluorescent display tube of the present invention.

The back plate BP has a through hole formed on the front surface and small on the back surface. A recess is formed as a cross-sectional shape, and the anode A and the phosphor PH are adhered to the inner surface of the recess. Although a metal plate is used as the substrate, almost all the surface of the metal is covered with the dielectric DL in order to insulate it from the anode and the like. An inorganic dielectric material containing glass is used so that a dense coating having a high insulating property can be formed. If electrodeposition is used as the coating method, even complicated shapes can be made uniform.

Etching may be used to process the through holes in the metal plate. A large number of holes and outer shapes can be formed at the same time, and processing accuracy is high. Moreover, if different etching masks are used on the front and back sides, the through holes as shown in FIG.

For the deposition of the anode and the phosphor, for example, simple printing can be applied. By squeezing ink into the through holes and filling it, and removing excess ink from the small holes by suction, it is possible to adhere along the wall surface.

Anode wiring is formed on the back surface of the back plate by printing, and a grid GR is formed on the front surface side by printing. In addition,
To ensure that the grid and anode are not short-circuited, an insulating layer is printed under the grid with glass ink. Also,
The small holes on the back side are hermetically sealed with a seal glass SG.
The seal glass layer may be formed not only in the small hole portion but also in a wide portion as a protective layer for the wiring layer. Further, when the seal glass is omitted, it is possible to configure the vacuum container by using another back plate.

Here, the thickness of the metal plate forming the back plate and the diameter of the hole formed will be supplementarily described.

When a metal substrate is used as a part of a vacuum container, it needs to have a certain thickness so as not to be largely deformed by atmospheric pressure. 0.2m for a fluorescent display tube with a width of 15mm
A minimum thickness of about 0.5 mm is required for a thickness of about m, and a width of 50 mm. Using etching, which is a preferred processing method as described above, the minimum width of the hole to be opened is about the thickness of the plate. Therefore, the area and pitch of the light emitting portion are limited by the thickness of the metal plate used. Also, the smaller the hole, the better for hermetically sealing the back hole. The holes are closed with a material such as the anode and its wiring, phosphor, seal glass, etc. When the printing technique is applied, the minimum width of the holes is 0.
It is preferably 4 mm or less. If it is larger than this, the airtightness tends to deteriorate, and the seal must be thickened to support the pressure difference. Furthermore, the deeper the recess of the through hole, the easier the grid control.

As described above, the factors required of the metal plate include the contradictory factors of increasing the plate thickness and decreasing the plate thickness, which may make the design difficult. The solution in such a case is to use a plurality of metal plates to form the through holes. It will be appreciated that this makes the design much easier. Although it is necessary to prepare and stack a plurality of metal plates, the steps after the insulating coating may be the same as above. It goes without saying that a configuration method other than that shown in FIG. 2 is also possible.

[0021]

As is apparent from the above description, the present invention has the following effects. (1) Since the grid can be fixed to the substrate by simple printing and is not deformed, a high electric field can be applied close to the cathode. Therefore, it is inexpensive and high brightness can be obtained. (2) Control is easy because the grid is closer to the cathode than the anode. (3) Even if the grid and the anode are arranged in a matrix, there is no need for a new insulating layer. (4) Since the planar insulating space between the grid and the anode may be small, a fluorescent display tube with a small light emitting portion pitch is possible. (5) If the formed substrate is used as a vacuum container, a thin one can be obtained, and by using the wiring on the back surface, the assembling space for the IC or the like can be made compact.

[Brief description of drawings]

FIG. 1 is a schematic partial sectional view showing an example of a conventional fluorescent display tube.

FIG. 2 is a schematic partial sectional view showing an example of a fluorescent display tube according to an embodiment.

[Explanation of symbols]

FG: front glass plate, BP: back plate, K: cathode, A: anode, PH: phosphor, GR: grid, DL: dielectric, S
G: Seal glass.

Claims (2)

[Claims] 1. A fluorescent display tube comprising a cathode, which is an electron emitter, a grid for electronic control, and an anode, the surface of which is coated with a phosphor, in a vacuum container. It is formed from a metal plate having a large through hole on the back side and a small through hole, and almost the entire surface of the metal plate is coated with a dielectric material containing glass, and an anode and a phosphor are provided inside the through hole.
A fluorescent display tube characterized in that a grid is fixed to the front surface of the substrate and an anode wiring is fixed to the rear surface of the substrate. 2. A hole having a minimum width of 0.4 mm on the rear surface side of the substrate.
The fluorescent display tube according to claim 1, wherein the back side holes are airtightly sealed with an inorganic material including glass and the substrate is used as a part of a vacuum container.