JP2934114B2 - Grid for fluorescent display tube - Google Patents

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 (VFD) grid used for controlling electrons emitted from a cathode.

[0002]

2. Description of the Related Art A fluorescent display tube displays a desired pattern by colliding thermoelectrons emitted from a cathode with a phosphor on an anode. The pattern design is clear and easy to see, and multicolor display is easy. It has excellent features such as a high degree of freedom and a low operating voltage, and is widely used particularly as a display device for automobiles and audio equipment.

[0003] In such a fluorescent display tube, in order to control electrons emitted from the cathode, those having a triode structure in which a grid is arranged between the cathode and the anode are often used. By applying a positive voltage to this grid, the electrons emitted from the cathode are accelerated and diffused toward the anode, and conversely, by applying a negative voltage, the electrons are cut off toward the anode and the display is erased. Or

[0004] As this grid, for example,
As described in JP-A-154059, JP-B-60-71063, JP-A-60-9040, etc., mesh-shaped stainless steel plates are most frequently used.

[0005] However, since this mesh-like grid is a bridge-like one that is supported by several legs and disposed in a hollow manner so as to cover the anode, uneven brightness may occur due to thermal deformation during driving. A problem such as short-circuit due to contact with the anode or cathode occurs. For this reason, in a fluorescent display tube using a mesh grid, the size of the grid and the driving voltage are significantly restricted.

Further, since the mesh is arranged so that the entire surface of the phosphor is covered with the mesh, a part of the emitted light is blocked by the frame portion of the grid occupying about 8 to 15% of the grid area, and the decrease in the amount of light and the brightness are reduced. It causes unevenness.

Furthermore, when a positive voltage is applied to one of the adjacent grids and a negative voltage is applied to the other grid, near the boundary between the two grids, the fluorescent light under the grid to which the negative voltage is applied is located. Some of the electrons attracted to the grid to which a positive voltage is applied are taken into the body, causing leakage light emission. For this reason, in the conventional technique, it is impossible to divide the grid without causing light emission due to leakage of the dense portion of the pattern.

On the other hand, Japanese Utility Model Laid-Open No. 3-52945 discloses that
There has been proposed a planar grid structure formed of a conductive material such as Al around a phosphor layer on an anode substrate.

FIG. 8 is a cross-sectional view schematically showing the grid structure. Reference numeral 20 denotes a glass anode substrate, 21a and 21b grids formed on the anode substrate 21, 22 an anode electrode, and 23 an anode electrode 22. Is formed on the upper surface of the substrate.

According to this grid structure, there is nothing obstructing the front surface of the phosphor as in a conventional grid made of a stainless steel plate.
In addition, various problems such as a problem of thermal expansion caused by providing the mesh grid can be solved.

[0011]

However, in this grid structure, since the grids 21a and 21b are formed directly and planarly on the anode substrate 20, the phosphor 23
In order to emit light uniformly to the end of the anode 23, a protruding portion (shown as O in the figure) of the anode electrode 22 below the phosphor 23 is formed, and the anode electrode 22 and the grid 21
a, 21b so as not to short-circuit them (P in the figure)
Is required). For this reason, it can be applied only to a sparse pattern having a sufficient space between segments, and the same problem as the conventional mesh grid remains.

Further, since the grid surface is at the same level or lower than the phosphor surface, the effect of diffusing electrons emitted from the anode or blocking electrons when a negative voltage is applied is poor. For this reason, the grid structure described in Japanese Utility Model Laid-Open Publication No. 3-52945 can only be used for static driving that does not require control by the grid.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and it is a grid for a fluorescent display tube that can divide a grid in a pattern dense portion without causing leakage light emission and can reliably control acceleration and cutoff of electrons. The purpose is to obtain.

[0014]

According to the present invention, there is provided a grid for a fluorescent display tube provided around a phosphor layer formed on an anode substrate. 20 μm or more above the phosphor layer top surface
It is characterized by comprising a protruding rib made of an insulating material and a conductive material layer for a grid formed on the top of the rib. Further, in the above configuration, the conductive material
The thickness of the material layer is 10 to 50 μm.

It is desirable that the top of the rib made of the insulating material protrudes at least 20 μm from the upper surface of the phosphor layer from the viewpoint of preventing short circuit between the grid formed thereon and the phosphor layer. If the protrusion amount is less than 20 μm, the effects of accelerating and blocking electrons are weakened.

The thickness of the conductive material layer formed on the top of the rib is preferably about 10 to 50 μm. 1
If it is less than 0 μm, the resistance increases, and if it exceeds 50 μm, drooling during printing tends to occur.

The width of the rib and the conductive material layer formed on the top of the rib is sufficient to achieve its purpose at 40 to 50 μm, and is therefore the minimum printable space in the current printing technology. Even if the interval of 40 μm is considered, grid division is possible if the interval of each segment is 120 μm or more.

The ribs made of an insulating material are formed by
A low-melting glass paste can be used as the material, for example, by a printing method or an etching method.

In the case of the printing method, 10 to 30 .mu.
m, and printing and drying are repeated 2 to 10 times to form. By performing printing by dividing into a plurality of pieces in this manner, it is possible to vertically and accurately form thin and high ribs having a width of 40 μm and a height of 150 μm, for example.

In the case of the etching method, after the ribs are formed, and in the case of the printing method, during the plurality of printings, the carbon serving as the anode electrode and the upper surface of the carbon are provided between the rib formation patterns. Print so that the phosphor is dropped.

Next, Ag, Al, Ni,
Alternatively, a conductive material made of carbon or the like is formed by the thick film printing method in the same pattern as the rib.

As a result, a grid for a fluorescent display tube made of a conductive substance is formed on the outer peripheral portion of the plurality of divided phosphor layers.

[0023]

According to the grid for a fluorescent display tube of the present invention, a conductive material layer serving as a grid is formed at least on tops of ribs higher than the phosphor layer. For this reason, the positional relationship of the grid with respect to the phosphor is advantageous for accelerating or blocking electrons, and is superior in terms of brightness and controllability of electrons, as compared with the conventional planar grid formed directly on the substrate surface. It will be. Further, since the ribs serve as partitions between the adjacent phosphor layers and have less influence on other phosphor layers, the grids can be arranged close to each other without causing light leakage. Further, unlike the planar grid structure disclosed in Japanese Utility Model Laid-Open Publication No. 3-52945 described in the prior art, the gap between the phosphor layer and the grid layer for preventing short circuit is not set in the plane direction but in the height direction. Therefore, the space between each pattern required for grid division can be reduced.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a grid for a fluorescent display tube according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a perspective view of a fluorescent display tube provided with a grid for a fluorescent display tube according to an embodiment of the present invention, FIG. 2 is a plan view of the essential parts, and FIG. 3 is a sectional view taken along line AA of FIG. It is.

1 to 3, reference numeral 1 denotes an anode substrate made of glass, 2 denotes an insulating layer made of a low-melting glass and a color pigment formed on the anode substrate 1 by a thick film printing method, and 3 denotes an anode layer. Through the through holes formed in the insulating layer 2, the carbon layer 4
And a lead conductor for connecting the lead pin 13 to the wiring conductor. Reference numeral 6 denotes a width 5 made of a low melting point glass formed by a thick film printing method.
0 μm insulative rib, and a rib 6
An aluminum conductive material layer 7 formed by thick-film printing is formed in the same pattern as that described above. Reference numeral 8 denotes a grid wiring for supplying a current to the conductive material layer 7 formed on the top of the rib 6. The grid wiring 8 is printed on the surface of the insulating layer 2 by a thick film printing method, and one end is connected to the pad 11. Thereby, wiring irrelevant to the conductor wiring 3 provided on the anode substrate 1 becomes possible. The ribs 6 and the conductive material layer 7 form a grid for controlling electrons emitted from the filament 12 shown in FIG. In addition,
Instead of forming the grid wiring 8 on the surface of the insulating layer 2 as in the above embodiment, the grid wiring 8 can be formed on the surface of the anode substrate 1 in the same manner as the wiring conductor 3. In FIG. 1, 13 is a lead pin, 1
Reference numeral 4 denotes a filament support frame, and 15 denotes a cover glass.

Inside the rib 6 is formed an anode carbon layer 4 dropped by the thick film printing method during the formation of the rib 6, and further on the upper surface thereof, similarly by the thick film printing method. The dropped phosphor layer 5 is formed.

In this embodiment, the width of the rib is 50 μm, and the protrusion amount from the upper surface of the phosphor layer is 100 μm.

As a result, as shown on the left side of FIGS.
The eight figure-shaped seven segments are covered by one grid, and the right-side equalizer pattern's 28 segments are covered by seven grids each of four grids, so that a structure having a total of six grid wirings 8 is provided.

In order to confirm the effect of the embodiment, a positive voltage is applied to the upper grid U and a negative voltage is applied to the lower grid L in the right equalizer pattern in which the minimum distance B between the segments is 150 μm. Then, a positive voltage was applied to all the anodes of the equalizer pattern, and a visual recognition test was actually performed.

As a result, no light emission was observed at the boundary of the grid. In addition, the conventional thickness of 50 μm,
A comparison with a mesh grid made of stainless steel with an aperture ratio of 85% revealed that the mesh was a shield in the conventional product and was inferior in the degree of clearness as compared with the product in the example. Was about 12% brighter.

As described above, in this embodiment, grid division can be performed at a minimum interval of about 120 μm without causing leakage light emission, so that the display quality can be greatly improved and the fluorescent display tube can be improved. It is possible to significantly reduce the size of the device itself. As a result, it is possible to apply the fluorescent display tube to a field where only a liquid crystal panel can be conventionally used.

FIG. 4 shows a wire grid type, and FIG.
An example of application to a double or quadruple anode matrix.
(A) is a plan view and (b) is a partial perspective view.

In the following embodiments, those corresponding to those shown in FIG. 1 are denoted by the same reference numerals.

By applying the present invention to a dot matrix tube as in this embodiment, it is possible to obtain a large grid pattern which is difficult to be affected by thermal deformation, which is particularly difficult with a mesh grid. This makes it possible to arrange the grid in the long side direction of the fluorescent display tube,
The duty cycle in dynamic driving is reduced from 1/100 to 1/200 of the prior art to 1/30 to 1
/ 40 can now be obtained. Therefore, when the same voltage is applied, the luminance is 3 times higher than that of the conventional product.
It can be up to 5 times.

FIG. 6 shows one of the dot matrices shown in FIG.
This is an example in which a cross-shaped auxiliary grid 9 for preventing leakage and light emission is further formed on dots, and apparently four dots constitute one dot. In this grid, four squares are formed on the same wiring layer and form one segment.

With such a configuration, even if the size of one dot is large and it is difficult to control the grid only by surrounding the segment with the grid, uniform display without leakage light emission can be obtained. Can be.

Further, as shown in FIG. 7, it is also possible to form an auxiliary grid 10 projecting within one dot, as shown in FIG. 7, instead of being completely cross-shaped as in the embodiment shown in FIG.

[0039]

According to the present invention, the following effects can be obtained.

(1) Since the rib completely surrounds the periphery of the phosphor layer, the grid can be finely divided without light emission without being affected by other adjacent grids, and the display quality is excellent even at a low voltage. Thus, a grid for a fluorescent display tube can be obtained.

(2) Since the conductive material layer for the grid is formed on the top of the rib, the distance to the cathode is short with respect to the phosphor surface, the electron acceleration and diffusion effects are excellent, and the conventional anode substrate Brighter display was possible with a lower applied voltage than that formed in a plane above.

(3) Unlike a conventional mesh grid, there is no deformation due to thermal expansion, so that a large grid pattern can be formed. Therefore, the present invention can be applied to a large-sized image display which has been difficult in the past.

(4) Efficient grid division closer to the theoretical value for performing dynamic driving has become possible.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a fluorescent display tube having a fluorescent display tube grid according to an embodiment of the present invention.

FIG. 2 is a plan view of a main part of the fluorescent display tube shown in FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 (a) is a plan view showing an application example of a grid for a fluorescent display tube of the present invention to a wire dot type dot matrix tube, and FIG. 4 (b) is a perspective view of the same.

FIG. 5A is a plan view showing an application example of a grid for a fluorescent display tube of the present invention to an anode matrix type dot matrix tube, and FIG. 5B is a perspective view of the same.

6 (a) is a plan view showing still another embodiment of the present invention, FIG. 6 (b) is a partial perspective view of the same, and FIG. 6 (c) is a partially enlarged plan view.

FIG. 7 is a partially enlarged plan view showing another embodiment of the auxiliary grid.

FIG. 8 is a schematic sectional view of a conventional planar grid structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode substrate 2 Insulating layer 3 Wiring conductor 4 Carbon layer (anode) 5 Phosphor 6 Rib 7 Conductive material layer 8 Grid wiring 9, 10 Auxiliary grid 11 Pad 12 Filament 13 Lead pin 14 Filament support frame 15 Cover glass

(56) References JP-A-62-290050 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 31/15

Claims (2)

(57) [Claims] In a grid for a fluorescent display tube provided around a phosphor layer formed on an anode substrate, a rib made of an insulating material protruding by 20 μm or more from an upper surface of the phosphor layer, and a top portion of the rib A grid for a fluorescent display tube, comprising: a grid conductive material layer formed on the grid. 2. The conductive material layer has a thickness of 10 to 50 μm.
2. The fluorescent display tube according to claim 1, wherein
For grid.