JPH04129143A - Fluorescent character display tube - Google Patents

Abstract

PURPOSE:To obtain a fluorescent character display tube having a phosphor layer of uniform brightness and high definition by taking the resistance of an insulation layer at 5 to 500MOMEGAcm as an expression of resistivity. CONSTITUTION:An insulation layer 4 is formed with a material having resistivity within the range of 5 to 500MOMEGAcm as a means for lowering the resistance value thereof to a level not causing leak luminescence between phosphor layers 3. Also, the disorder of electron flows 2 due to the electrification of the insulation layer 4 is eliminated by forming the aforesaid layer 4 in such a way as to have the resistivity within the range of 5 to 500MOMEGAcm as aforementioned, and a uniform electron beam 2 from a filament 1 comes to be incidental on a phosphor layer 3, resulting in uniform brightness. Also, the insulation layer 4 around the phosphor layer 3 is considered to have low positive potential, and the periphery of the phosphor layer 3 can receive a display of higher sharpness than in conventional type.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fluorescent display tube, Regarding fluorescent display tubes.

[Conventional technology]

Fluorescent display tubes have an insulating layer around the phosphor and are driven at particularly low voltages. This has the effect of connecting the wiring layer and the phosphor layer serving as the light emitting part via a through hole, insulating other parts, and insulating the wiring layer so that no current flows.

Conventionally, the properties required of this insulating layer were to be a perfect insulator, and high kneading properties were considered good in terms of resistance value. Therefore, the aim of improving the materials that form the insulating layer of fluorescent display tubes is to increase the insulation resistance.

Further, the material was a mixture of glass powder and a colorant such as black stencil, which was formed into a paste by screen printing or the like, and then fired to form an insulating layer.

FIG. 2 is a diagram illustrating the operating principle of an example of a conventional fluorescent display tube.

As shown in FIG. 2, the electrons emitted from the filament 1 flow into the phosphor layer 3 to which a positive potential is applied, and the phosphor layer 3 emits light. However, when the insulating layer 4 is negatively charged, The electron flow 2 at the outer periphery of the phosphor layer 3 receives a repulsive force and becomes non-uniform with respect to the center, where it enters the phosphor layer 3, as shown by the arrow.

Therefore, the brightness proportional to the electron flow 2 becomes non-uniform around the outer periphery of the phosphor layer 3, which is a problem.

This phenomenon is noticeable in fluorescent display tubes driven at low voltages with low electronic energy, and methods to prevent charging during handling and packaging materials have to be made of expensive materials with antistatic functions.

[Problem to be solved by the invention]

Since this conventional insulating layer is an insulator, it is easily charged, and when it is charged due to electrostatic induction from the outside, etc., and when it is negatively charged, it does not respond to the electron beam emitted from the filament around the phosphor layer. This has the disadvantage that the potential distribution of the insulating layer is disturbed and electrons do not enter the phosphor layer uniformly, resulting in low brightness around the insulating layer and uneven brightness of the phosphor layer.

An object of the present invention is to provide a fluorescent display tube with uniform luminance of a phosphor layer and high display quality.

[Means to solve the problem]

The present invention includes a glass substrate, an anode formed on the glass substrate, a phosphor layer covering the anode, a wiring layer connected to the anode, and a wiring layer formed around the phosphor layer. In the fluorescent display tube having an insulating layer covering the insulating layer, the insulating layer has a resistivity of 5 to 500 MΩ.

〔Example〕

FIG. 1 is a diagram showing the operating principle of an embodiment of the present invention.

In this embodiment, as shown in FIG. 1, a filament 1 is stretched at a distance from the phosphor layer 3, and the phosphor layer 3 is
An insulating layer 4 is formed.

The insulating layer 4 has a resistivity of 5 to 5 as a means of lowering the resistance value to a level that does not cause leakage of light between the phosphor layers 3.
It is made of a 500 MΩC material and is made of a paste made by adding and mixing ruthenium oxide differential powder, which is stable for use in fluorescent display tubes, as a conductive material to the glass powder and coloring material used conventionally.

In this way, by providing the insulating layer 4 with a resistivity of 5 to 500 MΩcm, the disturbance of the electron flow 2 due to the charging of the insulating layer 4 is eliminated, and uniform electrons 7N2 from the filament 1 enter the phosphor layer 3. As a result, the brightness becomes uniform.

Furthermore, since the insulating layer 4 around the phosphor layer 3 is considered to have a low positive potential, a clearer display can be obtained around the phosphor layer 3 than in the past.

〔Effect of the invention〕

As explained above, in the present invention, by setting the resistance of the insulating layer to 5 to 500 MΩcm in terms of resistivity, the insulating layer is not charged due to electrostatic induction, etc., and the electron flow becomes uniform, so that uniform display is always possible. This has the effect of improving display quality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the operating principle of an embodiment of the present invention, and FIG. 2 is a diagram showing the operating principle of an example of a conventional fluorescent display tube. DESCRIPTION OF SYMBOLS 1... Filament, 2... Electron flow, 3... Phosphor layer, 4... Insulating layer.

Claims (1)

[Claims] a glass substrate, an anode formed on the glass substrate, a phosphor layer covering the anode, a wiring layer connected to the anode, and an insulation formed around the phosphor layer and covering the wiring layer. 1. A fluorescent display tube comprising a layer, wherein the insulating layer has a resistance of 5 to 500 MΩcm in terms of resistivity.