JPS63202830A - Fluorescent character display tube and method for driving it - Google Patents

Abstract

PURPOSE:To eliminate the luminescence leakage and prevent the deterioration of the display quality by providing a conductive film as a new control electrode having nearly the same shape as a control electrode arranged on an anode substrate. CONSTITUTION:A display segment 2 and the first control electrode 3 surrounding the display segment 2 are formed on an anode substrate 1. A filament 4 arranged at a distance from the display segment on the anode substrate 1 is supported on a metal frame 8 under tension. A conductive film electrode 6 as the second control electrode having nearly the same shape as the first control electrode 3 is formed on the inner face of an upper glass 7 facing across the filament 4, and the positive voltage is applied. The luminescence leakage can be eliminated by this second control electrode, thereby the deterioration of the display quality can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrode structure of a fluorescent display tube and a method for driving the same.
In particular, the present invention relates to a fluorescent display tube in which an anode display segment and a control electrode are arranged on the same plane and a new control electrode is provided on an opposing glass surface, and a method for driving the same.

[Conventional technology]

Traditionally, this type of fluorescent display tube has an anode display segment (
Static type fluorescent light that displays one required character by selecting the electrodes connected to each display segment on the anode substrate and one grid placed between the display segment (hereinafter referred to as display segment) and the filament. There is a display tube, and it also has a grid divided into each digit to be displayed and a display segment that is commonly connected through each digit, and the grid of each digit is controlled in a time-sharing manner and displayed in accordance with the display timing of each digit. There is a dynamic type fluorescent display tube that selectively displays segments.

The grid in the static method is mainly provided to obtain uniformity of electrons, but this grid uses expensive metal and is prone to short circuits between the filament and the grid due to costly welding work and thermal deformation. , or a short circuit between the grid and anode occurred, resulting in decreased reliability.

Furthermore, when the number of display patterns increases, the number of lead electrodes also increases proportionally, so there is a problem that the size tends to increase, such as using a double lead type. On the other hand, in the dynamic type, although the number of slanted leads to which the segments of each girder are commonly connected is reduced, the material cost and welding process for the grid are required, and reliability is lowered due to thermal deformation of the grid.

In order to improve the above-mentioned drawbacks, as shown in Figure 3, in the static type, the mesh-like control electrodes that were placed on the anode substrate were replaced with display segments on the same plane on the anode substrate where the display segments were placed. The method used was to surround it with graphite, etc. This method had the advantage of eliminating expensive metal parts and welding processes.

[Problem that the invention seeks to solve]

However, when this method is applied to a conventional dynamic type fluorescent display tube, the lighting digit is turned on at the scan timing, the control electrode surrounding the display segment of the connected digit and the display segment that makes it emit light are turned on, but the remaining digits are turned on. A cutoff potential of about 1.5 times the filament potential is normally applied to the control electrode of the order of magnitude, and a high voltage is applied to the segment commonly connected to the lighting segment9.As a result, the scan pulse is not turned on. Conventionally, electrons reaching the anode were stopped at a cutoff voltage of about 1.5 times by the shielding electric field of the grid electrode placed between the anode and the filament, but now the grid electrode is formed on the same plane as the display segment. The controlled electrode requires a very deep cutoff voltage, close to the negative anode voltage, to create an electric field that shields the display segment. Particularly when the width of the display segment is wide, the central part of the display segment cannot be shielded, resulting in leakage of light and deterioration of display quality.

In contrast to the above-mentioned conventional fluorescent display tube, the present invention has a conductive film, which is a new control electrode, which has almost the same outer shape as the control electrode arranged on the anode substrate, on the inner surface of the glass facing the anode, and which is disposed facing the inner surface of the glass facing the anode. When the control electrode of the non-lighting digit on the anode is at cut-off potential, the voltage of the conductive film becomes positive and absorbs electrons, and the control electrode of the lighting digit becomes a positive high voltage, and the paired conductive film becomes 0. It has an original content that eliminates light emission leakage as a potential or a diffusion potential.

[Means for solving problems]

The fluorescent display tube of the present invention includes a first control electrode that surrounds the display segment of each digit on the same plane as the display segment on the anode substrate and is commonly connected to each digit; A second control electrode having approximately the same external shape as the first control electrode is provided on the opposing inner surface of the glass.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1A and 1B are a plan view and a sectional view showing a first embodiment of the present invention. A first control electrode 3 surrounding the surface segment 2 and the display segment 2 is formed on the anode substrate 1, and each electrode is wired with silver paste or the like and connected to a lead electrode 9 through an electrode pad 11.

A filament 4 placed at a distance from the display segment on the anode substrate 1 is supported under tension on a metal frame 8 and supplies an electron beam. Note that, although not shown, a phosphor is arranged on the surface of the display segment. On the inner surface of the upper glass 7 facing each other with the filament in between, a conductive film electrode 6 as a second control electrode having almost the same shape as the first control electrode 3 is formed of, for example, a transparent Nesa film. It is connected to the outside by a lead electrode 9 with a tongue-shaped electrode 10 in contact therewith. The anode substrate 1 forms a vacuum container with a spacer glass 5 and a top glass 7.

In the fluorescent display tube of the present invention, a pulse as shown in FIG. 4 is applied to the first control electrode 3 of each digit as in the dynamic type fluorescent display tube. At this time, in the pattern portion to emit light, when the first control electrode 3 is turned on, the display segment is also turned on, and the conductive film electrode 6 as the second control electrode has the first
The filament potential is applied at the same timing as the control electrode, but in other digits, a cutoff potential of about 1.5 times the conventional level filament voltage is applied to the first control electrode, and a positive voltage is applied to the conductive film electrode 6. voltage is applied. In this state, in the non-lighting girder, electrons do not reach the anode due to the cutoff voltage and the positive potential on the top of the filament, so leakage and light emission can be completely prevented.

FIGS. 2(a) and 2(b) are a plan view and a sectional view showing a second embodiment of the present invention.In this example, the display pattern is applied to a type of fluorescent display tube where the emitted display pattern is viewed from the back. The anode substrate 1 is formed of a thin film, and the display segments have slits on the back side to allow light to leak out.The first control electrode 3 is formed to surround the display pattern in the same manner as in the first embodiment. In this embodiment, since the conductive film electrode 6 as the second control electrode 6 is formed of graphite or a vapor-deposited film of Al, there is an advantage that light leakage is also prevented.

〔Effect of the invention〕

As explained above, in the present invention, since each control electrode can be made by the printing method in the same way as the anode, the material costs and assembly man-hours for metal parts can be omitted, and filament grids, which conventionally occur due to thermal deformation of metal parts, can be omitted.

It also prevents deterioration in reliability such as short circuits between the grid and anode, making it possible to produce inexpensive and highly reliable fluorescent display tubes. Although this example shows an example in which a filament potential is applied to the conductive film electrode of the lighting girder, a diffusion potential may also be applied, as in the conventional case. Further, the shape of the conductive film electrode as the second control electrode is approximately the same as the outer shape of the first control electrode, but it can be easily imagined from the present invention that the shape may be corrected depending on the display pattern.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view showing a first embodiment of the fluorescent display tube of the present invention, FIG. 1(b) is a sectional view taken along line AA' in FIG. 1(a),
FIG. 2(a) is a plan view showing the second embodiment, FIG. 2(b) is a plan view showing the second embodiment.
3(a) is a plan view of a conventional fluorescent display tube, and FIG. 3(b) is a sectional view taken along line c-c in FIG. 3(a).
'This is a cross-sectional view. 1...Anode substrate, 2...Display segment, 3...
control electrode, 4... filament, 5... spacer glass, 6... conductive film electrode, 7... top glass, 8...
. . . metal frame, 9 . . . lead electrode, 10 . . . tongue-shaped electrode, 11 . . . electrode pad, 12 . 1st audience 2nd 3rd ward

Claims (1)

[Claims] 1) A first control electrode that is on the same surface as the display segment on the anode substrate, surrounds the display segment of each digit, and is commonly connected to each digit; A second control electrode is arranged on the inner surface of the glass facing the first control electrode and has a shape substantially the same as the first control electrode, and a second control electrode is arranged between the first control electrode and the second control electrode. What is claimed is: 1. A fluorescent display tube comprising: filaments disposed in the tube; 2) a first control electrode on the same surface as the display segment on the anode substrate, surrounding the display segment of each digit and commonly connected to each digit; and a first control electrode disposed on the anode substrate. a second control electrode disposed on the opposing inner surface of the glass in a shape substantially the same as the first control electrode; and a filament disposed between the first control electrode and the second control electrode. In the method for driving a fluorescent display tube, a positive voltage is applied to the second electrode of the digit where the scan pulse is off during driving, and a cut-off voltage is applied to the first control electrode. , a method for driving a fluorescent display tube, characterized in that a filament potential or a diffusion potential is applied to the second electrode in the order in which the scan pulse is on, and a positive voltage is applied to the first control electrode. .