JPS62154541A - Fluorescent character display tube - Google Patents

Abstract

PURPOSE:To make longitudinal luminosities uniform, by dividing a grid of a fluorescent tube into more than three pieces, and impressing more than two kinds of potential on them. CONSTITUTION:Grids G1, G2 and G3 and G1a, G2a and G3a by threes are placed at both sides of a phosphor dot array 10 in parallel. The grid G2a has an almost double area over that of these grids G1a and G3a, while the grid G1 situated at both ends and these grids G3 and G3a are connected with one another. Each of cathode filaments 12 and 12 or a hot cathode is installed in an upper part of the phosphor dot array 10 and in a position going along the longitudinal direction of the phosphor dot array 10. These grids G1-G3 and G1a-G3a divided into three segments are given different voltage each. As for a grid voltage vs. brightness characteristic, when it is given potential with such relations as VG1 < VG2, brightness of the dot situated in the filament central part comes high so that equalization in light distribution is promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fluorescent display tube that displays information using fluorescent light emitted when thermoelectrons collide with a fluorescent surface.

(Prior Art) A fluorescent display tube is made by forming a fluorescent surface on a large number of segment electrodes arranged in one or more rows in one direction, and enclosing this together with a hot cathode in a vacuum container. Thermal electrons are generated from the phosphor, while a positive voltage is applied selectively to the segment electrodes depending on the information to be displayed, attracting thermionic electrons to the selected segment electrodes, and these thermionic electrons collide with the fluorescent surface. Information is displayed using the fluorescent light emitted by the display, and they are already well known as barcode display tubes and phosphor array tubes.

First, referring to FIG. 7, the outline of a fluorescent display tube will be explained by taking a fluorescent dot array tube as an example.

In the seventh factor, reference numeral 20 indicates a substrate made of glass, ceramic, resin, or the like. A series of segment electrodes 21 are provided in nine rows in the longitudinal direction of the substrate on the substrate 20, and a fluorescent surface 26 is formed on each of the segment electrodes 21. The size of each fluorescent surface is 40
The size of the fluorescent surface is extremely small, such as 40 μm x 50 μm to 50 μm, but in FIG. 7, the size of the fluorescent surface is shown larger than that of the other members.

On both sides of the arrangement of the fluorescent surfaces of the substrate 20, there are recording layers 22a1.
22b is formed along the longitudinal direction of the substrate, and grid electrodes ti 23a and 23b are formed on these, respectively. In FIG. 7, reference numeral 24 indicates a tungsten wire as a hot cathode stretched in the longitudinal direction of the substrate, the surface of which is coated with an electron emissive material such as BaOtSrO. Further, reference numeral 25 denotes a face member made of a transparent material such as glass, which is integrated with the substrate side as shown in FIG. Thus,
Substrate 20, insulator layer 22a.

22b, grid electricity 4iffl 23a, 23b
, the face member 25 forms a closed space, and within this space there are a segment electrode 21 and a fluorescent surface 26 formed by a fluorescent layer.
, the hot cathode 24°24 is confined. The closed space is highly evacuated.

When an appropriate voltage is applied to the grid electrodes 23a and 23b and an alternating current of several tens of milliamps is passed through the hot cathode 24.24, the hot cathode 24.24 is heated by the sealing heat and emits thermionic electrons. do. In such a situation,
When a positive voltage is applied to one of the segment electrodes 21 to make it a positive potential, the thermoelectrons are attracted to the electrode portion of the segment electrode having a positive potential, and when sucked into the electrode portion, the fluorescent surface 26 fluoresces. Excite the energy state of matter. The excited fluorescent substance emits fluorescent light when returning to the ground state.

This fluorescent light is observed through the face member 25.

Such a fluorescent dot array tube is used as a part of the optical system of an optical printer or as a bar code display tube.

By the way, since AC voltage is applied to the hot cathodes 24.24 in a center tap manner as shown in FIG.
．． An intermediate potential is applied to approximately the center of 24, and an alternating current voltage is applied to the ends. However, the relationship between hot cathode voltage and brightness is almost a quadratic function, as shown in Figure 10.
Therefore, the brightness of the phosphors located toward the ends of the hot cathode becomes higher than the center of the hot cathode, resulting in a problem of non-uniform brightness in the longitudinal direction of the fluorescent tube.

(Objective) An object of the present invention is to solve the above problems of the prior art and provide a fluorescent display tube having uniform brightness in the longitudinal direction.

(Structure) FIG. 1 shows an example of fluorescent dots and an array tube according to an embodiment of the present invention. A phosphor dot array 10, which is a minute light emitting segment array, is arranged approximately at the center of the substrate 11, and on both sides of the phosphor dot array 10, there are three grids G1-Gz, G3 and Gsa.

G 2 a + G 3 a are juxtaposed. In this case grid Gl.

G2 and G3 each occupy approximately the same area, but grid Q2a has approximately twice the area of each of grid (r+a and Gaa). Gaa are each connected to each other.Cathode filament (hereinafter simply referred to as filament) 12.1 which is a hot cathode
2 is stretched above the phosphor dot array 10 and along the longitudinal direction of the phosphor dot array 10. One end of the filament 12.12 is supported by a filament support 13 made of an elastic plate and given a predetermined tension.

Now, grids G1 to 3 are divided into three segments.
Different voltages are applied to each of Gla to 3al. For example, the center grid G2 r Gza has VG
The basic idea is to apply a potential of VGl (VGl<VGl) to other grids located near the ends. In general, as shown in Figure 2, the grid voltage vs. brightness characteristic means that when a potential is applied in the relationship VGI<VGl, the brightness of the dot located at the center of the filament becomes higher, so the light intensity distribution becomes more uniform. It is easy to understand that this can be achieved. In this case, intergrid insulation part #1
．． #l and? It is important for uniform distribution of light quantity that 2tP2 be set to 5 so that the dots are not too close to each other on both sides of the dot array. In other words, a better result is obtained if the distance l is increased to a certain extent.

Another embodiment of the present invention is shown in FIG.
grid G+a r G20 * G3Q, but the grid IJ located on the other side, that is, the lower side
The throat G40 is integral and not divided. The grid ends on both sides are respectively connected to each other. As clearly shown in the figure, a potential of VO2 is applied to the central part G20 of the dividing grid, and a potential of Vcl (Vat < VO2) is applied to the other parts.
). As a result, if VGI r VO2 is selected to an appropriate value, the effect of substantially uniformly distributing the light amount can be sufficiently obtained, and this method has the advantage of being easy to manufacture in terms of accuracy and manufacturing.

FIG. 4 shows yet another embodiment of the present invention, which is similar to the embodiment shown in FIG. 1 in that a split-type grid is arranged, but the shape of the insulation portion between the grid segments is It is characterized by being oblique to the arrangement direction of the dot array. As shown in the figure, the grids placed in the center of the filament and on both sides of the dot array are
There is an advantage that the influence of the grid spacing is small even when the potential of O2 and the grid arranged at the end of the filament are set to the potential of VGI. Note that, as clearly shown in FIG. 5, it goes without saying that the grid end portions do not have to be oblique but may be crank-shaped.

FIG. 6 shows yet another embodiment of the present invention. This case is basically the same as the embodiment shown in FIG. 3, but since the shape of the grid end is oblique with respect to the dot array arrangement direction, in this sense it is different from the embodiment shown in FIG. The effect is close.

The present invention is not limited to the number of segment divisions exemplified in the above explanation, and it goes without saying that better effects can be obtained by increasing the number of segments further and applying the potential more finely. Nor.

Furthermore, it should be understood that the potential VGI*VO2 does not represent the same value in each embodiment, but merely provides a magnitude relationship of vGl<VO2.

In the above description, a fluorescent dot array tube was exemplified, but the present invention is naturally applicable not only to display tubes but also to fluorescent tubes such as illumination tubes.

(Effects) In the present invention, since the grid of the fluorescent tube is divided into three or more parts and different potentials are applied to these parts, it is possible to correct the non-uniform distribution of the amount of light caused by the electric action of the filament. This results in the effect that the brightness can be made uniform in the longitudinal direction of the fluorescent tube.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing one embodiment of the present invention, FIG. 2 is a diagram showing the relationship between grid voltage and brightness, and FIGS. 3 to 6 are plan views showing other embodiments of the present invention. 7 and 8 are partially exploded views and cross-sectional views showing an example of a fluorescent display tube, FIG. 9 is a diagram for explaining an AC voltage applied to a conventional filament, and FIG. 10 is a diagram showing a filament. FIG. 3 is a diagram showing the relationship between voltage and brightness. 11.20...Substrate, 12.24...Filament as hot cathode, 23a, Gl~3. GIa~3a,G
lo~4゜・・・Grid electrode, Vat + VO2・
··potential. Non 7 Mouth party 2 Roa 18/TosuzuE form wa Zurei Z et al 5 illustration etc etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg etg.

Claims (1)

[Claims] In a fluorescent tube having grids arranged on both sides with a microluminescent segment array in between, and a cathode filament stretched above each grid along the arrangement direction of the microluminescent segment array, at least one grid 1. A fluorescent display tube, characterized in that the tube is divided into at least three segments, and at least two types of potentials are applied to each segment.