JPS63146329A - Fluorescent character display tube and driving method thereof - Google Patents

Abstract

PURPOSE:To uniformize the extent of light emitting luminance of a phosphor of its layer as well as to make display quality ever so better, by setting up and electronic control electrode in an intermediate position between two filaments and also between these filaments and a transparent conductive film. CONSTITUTION:An electronic control electrode 12, using a pure tungsten wire, is set up between filament 7 and a transparent conductive film 9 at an intermediate position beween two filaments 7 in parallel with the tensile direction of the linear filament 7. And, DC bias and AC voltage are overlappingly impressed on the said electrode 12. With this constitution, diffusion of an electron out of the fialment 7 is dynamically controlled, and thereby electron density distribution on an anode 4 can be almost uniformized within the AC-cycle. Therefore, light emitting luminance of a phosphor in a phosphor layer 5 is uniform enough, thus display quality is improvable.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fluorescent display tube and a method for driving the same.

[Conventional technology]

Conventionally, the electrodes of a fluorescent display tube include an anode coated with a phosphor layer,
It consisted of a lattice, a filament, and a transparent conductive film.

FIG. 3 is a sectional view showing an example of a conventional fluorescent display tube.

A fluorescent display tube consists of a substrate glass 1 and a plurality of conductor pieces provided on the substrate glass 1. 4° grid 6. A wiring layer 2 connected to the filament 7, and a lead terminal 1 connected to the wiring layer 2 and whose tip is pulled out of the tube and connected to an external circuit.
1, a plurality of filaments 7 stretched at intervals with respect to the anode 4, a grid 6 disposed between the anode 4 and the filaments 7, and a substrate glass 1 having a transparent conductive film 9 on its inner surface.
It consists of a transparent cover glass that is sealed to the

Electrons emitted from the filament 7 are accelerated and diffused by the potential of the lattice 6 and enter the anode 4. Since the anode 4 is coated with a phosphor layer 5, the phosphor emits light when stimulated by electrons incident on the anode 4.

The transparent conductive film 9 is set to the same potential as the filament 7 to shield external electric fields. With such an electrode structure, it is difficult to make the luminance of the phosphor of the phosphor layer 5 completely uniform. This non-uniformity in brightness is called display unevenness, and often occurs in a direction perpendicular to the direction in which the linear filament 7 is stretched, and is particularly noticeable in the vicinity directly below the filament 7. The main reason for this is that electron currents flow into the flat anode 4 from the plurality of linear filaments 7. In order to increase the luminance of the phosphor in the phosphor layer 5, the number of filaments 7 is increased, and the distance between the filaments 7 is narrowed. 9 is 1.5 times or more, this is also due to the fact that the diffusion of electrons from the filament 7 is restricted by the potential of the filament 7 and the transparent conductive film 9.

FIG. 4 is a circuit diagram for explaining an example of a conventional method for driving a fluorescent display tube.

Conventionally, the transparent conductive film 9 was set to the same potential as the filament 7 to shield external electric fields, but in order to solve display unevenness, there was a method of setting the potential of the transparent conductive film 9 to the potential of the grid 6. . However, in this method, unless the distance between the anode 4 and the filament 7 is approximately equal to the distance between the filament 7 and the transparent conductive film 9,
Since the distribution of the electron flow towards the transparent conductive film 9 and the flow of electrons towards the transparent conductive film 9 are different, no fundamental countermeasure has been taken.

[Problem that the invention seeks to solve]

As described above, in the conventional fluorescent display tube, the density of electrons incident on the anode 4 is determined by the positions and potentials of the filament 7 and the transparent conductive film 9. The electron density distribution of the anode 4 tends to vary in the direction perpendicular to the direction in which the linear filament 7 is stretched, and the luminance of the phosphor in the phosphor layer 5 on the anode 4 tends to become non-uniform. There was a problem.

An object of the present invention is to provide a fluorescent display tube with uniform luminance of the phosphor in the phosphor layer 5 and good display quality, and a drive circuit thereof.

[Means for solving problems]

The fluorescent display tube of the present invention comprises a substrate glass, a plurality of conductor pieces, an anode provided on the substrate glass, a phosphor layer coated on the anode, and a wiring layer connected to the conductor pieces. and a plurality of filaments stretched at intervals with respect to the anode, a grid disposed between the anode and the filament, and a transparent conductive film for shielding an external electric field on the inner surface, and the substrate glass is In a fluorescent display tube having a sealed transparent cover glass, an electronic control electrode is disposed at a position intermediate between the filaments and between the filament and the transparent conductive film.

A method for driving a fluorescent display tube according to the present invention includes an anode coated with a phosphor, a grid, a filament, a transparent conductive film, and a position intermediate between the filaments and the transparent conductive film. A DC bias and an AC voltage are applied in a superimposed manner to the electronic control electrode of a fluorescent display tube having an electronic control electrode disposed between them, and the electron flow emitted from the filament is controlled to cause the phosphor layer to emit light. It is composed of:

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a fluorescent display tube of the first invention.

A wiring layer 2 is formed on the substrate glass 1 by thin film printing, thick film printing, etc. Insulating layer 3. An anode 4 is formed and a phosphor layer 5 is formed on the anode 4.
is coated. The wiring layer 2 includes an anode 4. Lattice 6. Filament 7, electronically controlled [! There are 12 connections from which each tip is led out of the tube through a lead terminal 11. The electronic control electrode 12 is disposed between the filament 7 and the transparent conductive film 9, using a pure tungsten wire, in parallel to the direction in which the linear filament 7 is pulled, at an intermediate position between the filaments 7 and 9.

FIG. 2 is a circuit diagram for explaining an embodiment of the method for driving a fluorescent display tube according to the second invention.

A DC bias and an AC voltage are superimposed and applied to the electronic control electrode 12 so that the electron current emitted from the filament 1-7 is incident on the anode 4 at a uniform density.

Since the electronic control electrode 12 is located near the filament 7, it is possible to control electron emission and diffusion from the filament 7 with a small potential difference with respect to the potential of the filament 7.

FIGS. 5(a) and 5(b) are an electron trajectory diagram and an electron density distribution diagram showing the results of analysis by an electronic computer when a bias voltage of -5 V is applied to the electronic control tlt&12 with respect to the potential of the filament 7.

This analysis result shows that by applying a bias voltage of -5V to the electric potential of the filament 7 to the electronic control electrode 12, electrons are concentrated and emitted onto the anode 4, which is sufficiently effective. Further, the electric potential of the filament 7 is applied to the electronic control electrode 12 at OV, -2V, -3V, -5.
According to the analysis results of the integral value of the electron density distribution by an electronic computer when a bias voltage of V is applied, it has been confirmed that the electron density distribution on the anode 4 is more uniform. This shows that the electron density distribution on the anode 4 can be made more uniform within the AC cycle, and that by superimposing the AC voltage on the bias voltage, the phosphor of the phosphor layer 5 on the anode 4 can emit light. A fluorescent display tube with more uniform brightness and better display quality can be obtained. The frequency of AC voltage is 1
If the frequency is 00 Hz or more, no flicker is visually observed, and uniform light emission from the phosphor of the phosphor layer 5 can be obtained. In the first invention, the linear electronically controlled type [i12 is arranged between the filament 7 and the transparent conductive film 9 at the intermediate position between the filaments 7 and 9, but the shape and position are different from the shape of the anode 4 and the display Any shape, position, and arrangement direction that makes the electron density distribution on the anode 4 uniform according to the brightness characteristics can be applied.

〔Effect of the invention〕

As explained above, in the present invention, the electronic control electrode 12 is disposed between the filament 7 and the transparent conductive film 9 at an intermediate position between the filaments 7 and 1.
By applying a DC bias and an AC voltage in a superimposed manner to 2, it is possible to dynamically control the diffusion of electrons from the filament 7 and make the electron density distribution on the anode 4 almost uniform within the AC cycle. , the luminance of the phosphor in the phosphor layer 5 is uniform and the display quality can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a fluorescent display tube according to the first invention, FIG. 2 is a circuit diagram illustrating an embodiment of a method for driving a fluorescent display tube according to the second invention, and FIG. The figure is a sectional view showing an example of a conventional fluorescent display tube, FIG. 4 is a circuit diagram for explaining an example of a conventional method of driving a fluorescent display tube, and FIG. 5(a),
(b) is 15% with respect to the electric potential of the filament at the electronic control electrode.
3 is an electron trajectory diagram and an electron density distribution diagram showing the results of analysis by an electronic computer when the bias voltage (2) is applied. FIG. DESCRIPTION OF SYMBOLS 1... Substrate glass, 2... Wiring layer, 3... Insulating layer, 4... Anode, 5... Phosphor layer, 6... Grid, 7
...Filament, 8...Cover glass, 9...
Transparent conductive film, 1°...Frit glass, 11...Lead terminal, 12...Electronic control electrode, 13...DC bias source, 14...AC voltage source. (-tail, big inside 1..
・Sudaku” 1 xun 3 figures

Claims (2)

[Claims] (1) A substrate glass, an anode comprising a plurality of conductor pieces and provided on the substrate glass, a phosphor layer coated on the anode, a wiring layer connected to the conductor pieces, and an anode provided on the substrate glass. A transparent conductive film having a plurality of filaments stretched at intervals, a grid disposed between the anode and the filament, and a transparent conductive film on the inner surface for shielding an external electric field and sealed to the substrate glass. What is claimed is: 1. A fluorescent display tube having a cover glass, characterized in that an electronic control electrode is disposed at an intermediate position between the filaments and between the filament and the transparent conductive film. (2) An anode coated with a phosphor, a grid, a filament, a transparent conductive film, and an electronic control electrode disposed at an intermediate position between the filaments and between the filament and the transparent conductive film. A fluorescent display tube comprising: applying a DC bias and an AC voltage in a superimposed manner to the electronic control electrode to control the flow of electrons emitted from the filament to cause the phosphor layer to emit light. How to drive a display tube.