JPH0438452Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is applicable to a fluorescent display tube with a triode structure.
It relates to a structure for preventing vibration of a filament cathode (hereinafter referred to as filament) and preventing electrical contact between the filament and control electrode (hereinafter referred to as grid), and is particularly applicable to high-intensity tubes and display patterns. The present invention relates to a structure of a fluorescent display tube that is useful when applied to a complex fluorescent display tube.

[Conventional technology]

Conventionally used fluorescent display tubes generally have an anode on which a phosphor is coated to form a display pattern on the upper surface of a substrate made of an insulator, and a grid provided above and opposite to the display pattern. Furthermore, a filament is stretched above the grid, and the electrode parts such as the anode, the grid, and the filament are sealed in a vacuum container part.

However, in the case of, for example, a fluorescent display tube that displays a large number of digits, the filament is provided parallel to the direction in which the display sections of each digit are arranged in parallel, and the filament is stretched so that it is common to each display section. When installed, there was a problem that the attached filament became long, making it vulnerable to vibration. In other words, when a fluorescent display tube receives an impact, the filament vibrates up and down, and the electric potential between the filament, the grid, and the anode display section changes, causing flickering of light, and in some cases, when the vibration becomes large, the filament may vibrate. Accidents have also occurred in which wires have come into contact with the grid, resulting in wire breakage.

As a solution to this problem, a fluorescent display tube shown in FIGS. 4 and 5 has been used.

To explain the conventional fluorescent display tube shown in FIGS. 4 and 5, an anode 2 is provided on the upper surface of a substrate 1, and a phosphor 3 is deposited on the upper surface of the anode 2 to form a display area. 4 is formed. The display section 4
A grid 5 made of a mesh-like metal fine enough not to obstruct observation of the display section 4 is fixed to a spacer frame 7 which is a holding section thereof, and is arranged above the grid 5 opposite to the display section 4. The filament 8 is parallel to the direction in which the display section 4 and the grid 5 are arranged in parallel.
is installed on a rack. Therefore, between the adjacent grids 5, a substantially rectangular plate made of an insulating material with low thermal conductivity, such as mica, is attached to the substrate 1 by a sealing material 9a or a mounting bracket. It is fixed and erected to form a damper 9, and the upper edge 9b of the damper 9 is erected so as to be close to and opposite to the filament 8.

In the above configuration, when the fluorescent display tube is subjected to an impact, the filament 8 vibrates with a large amplitude using the mounting portions at both ends (not shown) as fulcrums, but the vibration in the direction perpendicular to the substrate 1 Since the edge 9b presses and supports the filament 8, the distance between the filament 8 and the grid 5 and display section 4 is maintained constant.

[Problem that the invention attempts to solve]

In recent years, in fluorescent display tubes used for example in automobile graphic panels and audio equipment display panels, it is necessary to incorporate display parts of various shapes into one display tube, and at the same time, the number of display parts itself has also increased. As a result, the grid shape is becoming more complex and the distance between display parts is becoming narrower. Therefore, in order to prevent the filament from coming into contact with the grid due to vibration, installing a damper on the board between the grids is a difficult task that requires skill in fluorescent display tubes where the display parts are close to each other. Furthermore, there was a problem that the conventional structure could not be used for grids with complex shapes that were not linear.

Also, especially in high-intensity tubes, the distance between the filament and the grid is narrowed to increase perveance. Therefore, the current flowing into the grid is large, so when electricity is passed, the temperature of the grid rises and the metal expands, as shown in Figure 3.
The grid 5, which is made of metal formed into a mesh shape, may be curved upward. As the perveance increases due to deformation, the deformation increases, but as mentioned above, because the distance between the filament 8 and the grid 5 is narrow, the filament 8 and the grid 5 come into contact, and a high voltage is applied to the filament 8. In some cases, so-called thermal runaway that damaged the filament 8 occurred. However, since the conventional damper 9 is fixed on the substrate 1, the height of the upper edge 9b that supports the filament 8 is constant. Therefore, as described above, when the grid 5 is thermally deformed, the distance between the filament 8 and the grid 5 cannot be maintained at a predetermined value, and the fluctuation in the brightness of the display section 4 cannot be suppressed. There is a problem that if the amount of deformation of the grid 5 exceeds the height of the damper 9, there is a risk of thermal runaway.

[Purpose of invention]

The present invention was developed to solve the above-mentioned problems, and has a filament vibration prevention structure that can be applied to fluorescent display tubes with complex display patterns, as well as a structure that can prevent grids from thermally deforming in high-brightness tubes. It is an object of the present invention to provide a highly reliable fluorescent display tube that can prevent thermal runaway by maintaining a constant distance between a filament and a grid.

[Means for solving problems]

In order to achieve the above object, the present invention has the following configuration.

That is, in a fluorescent display tube having a triode structure having a filament, a grid, and an anode, a protrusion made of low-melting frit glass as the main component and containing a conductive substance is formed on the upper surface of the grid or its holding part in proximity to the filament. It is characterized by what it did.

Further, according to the present invention, the protrusion may be arranged in a direction perpendicular to the filament.

[Effect]

In the above-mentioned configuration, when the fluorescent display tube is subjected to an impact, the filament vibrates using the mounting parts at both ends as fulcrums, but the protrusions mainly made of insulating material provided on the top surface of the grid push the filament into contact. Since the anode substrate is supported, vibrations in a direction perpendicular to the anode substrate are suppressed, and flickering due to variations in brightness is prevented. Furthermore, when the grid is thermally deformed and curved toward the filament, the protrusion provided on the top surface of the grid also approaches the filament, so the distance between the filament and the grid is less than or equal to the height of the protrusion. Thermal runaway is reliably prevented.

Furthermore, if the protrusions are formed from a paste that is mainly composed of low-melting frit glass and contains a conductive substance, they can be arranged in any shape according to the shape of the grid by means such as printing. Not only can it be used, but since it has conductivity, it can also prevent electron charging.

Furthermore, if the protrusion is arranged in a band shape in a direction perpendicular to the filament, the filament can be supported reliably.

〔Example〕

The present invention will be explained below with reference to an embodiment shown in FIGS. 1 and 2.

FIG. 1 is a partially cutaway plan view of a statically driven fluorescent display tube according to an embodiment of the present invention, and FIG. 2 is a sectional view of the main part of FIG. 1. The display unit 13 provided on the substrate 11 is provided with a plurality of anode conductors 14 via wiring conductors 12, each having a configuration in which a plurality of characters, numbers, etc. can be selectively displayed. A phosphor layer 15 is deposited thereon. Above the display section 13, there is a grid 17 formed of mesh-like metal at a position facing each display section 13.
7 is fixedly disposed on a spacer frame 16 serving as a holding section. Above the grid 17, a plurality of filaments 18 are arranged at predetermined intervals in parallel to the direction in which the display sections 13 are arranged. It is tensioned by the spring force of the section 19.

Now, on the spacer frame 16 between the grids 17, one or a plurality of protrusions 20 as required are formed and disposed in a direction perpendicular to the filament 18. In this case, the protrusion 20 is
It may also be formed directly on the surface of the grid 17 facing the filament 18. In particular, in the case of a type of fluorescent display tube in which the grid 17 is directly fixed onto the substrate 11 without using the spacer frame 16, the projections 20 are formed directly on the grid 17. The protrusion 20, as shown in FIG.
The cross section is approximately triangular, and in this example, the width is 1.0 mm.
It is formed to have a height of 0.3 mm and a length of 25 mm, and the distance from the filament 18 to the filament 18 is 0.2 mm. The protrusion 20 is formed mainly of an insulating material and containing a conductive substance.
In this embodiment, low-melting fritted glass containing PbO as the main component was used as the insulating material, but even if other insulating materials are used, the coefficient of expansion should be approximately the same as that of the 426 alloy forming the spacer frame 16. is desirable. Furthermore, carbon was used as the conductive material.

Next, a procedure for forming the protrusion 20 on the spacer frame 16 of the grid 17 will be explained. First, a binder such as ethyl cellulose or nitrocellulose is added to low-melting fritted glass whose main component is PbO, and an organic solvent such as butyl carbitol or terpineol is mixed to form a paste. Here, a conductive substance such as carbon is included in the paste in order to impart some degree of conductivity. That is, the protrusion 20 can be made to have a predetermined resistance value (for example, about several tens of ohms to several hundred kilohms) by changing the amount of the conductive substance mixed into the paste. Therefore, it is possible to apply a positive potential to the protrusion 20 during use of the fluorescent display tube so that the protrusion 20 is not charged with negative static electricity.

Next, the paste is applied in a predetermined shape onto the spacer frame 16 between the grids 17 by screen printing. Then 400℃
The frit glass is fixed by firing at ~500°C to form the protrusion 20.

Next, the operation of the above configuration will be explained. When the fluorescent display tube is subjected to a shock or the like during operation, the filament 18 vibrates about the two mounting parts 19, 19, but the protrusion 20 provided on the upper surface of the spacer frame 16 of the grid 17
supports the filament 18, so the substrate 1
Vibration in the direction perpendicular to 1 is suppressed, and the distance between the filament 18 and the grid 17 is approximately constant, eliminating flickering due to variations in brightness. Further, since the protrusion 20 has a required resistance value, even if it comes into contact with the filament 18, a large current will not flow between the filament 18 and the grid 17.

Furthermore, in the fluorescent display tube during operation, when the temperature of the grid 17 rises and thermal expansion occurs and approaches the filament 18, the protrusion 20 provided on the upper surface of the spacer frame 16 of the grid 17
The filament 18 also approaches the filament 18.
The grid 17 and the filament 18 are pressed against each other.
Since the height of the protrusion 20 is maintained between the protrusion 20 and the protrusion 20, the occurrence of thermal runaway is reliably prevented.

In the embodiment invented above, the protrusion 2
The shape of the filament 0 is set as described above, but it may be any cross-sectional shape with a small surface area that can suppress the charge of electrons from the filament 18 as much as possible, and furthermore, it may be formed in a bent shape according to the shape of the grid 17. It can also be arranged. Moreover, it is free to provide it not only in one place but also in multiple places. Accordingly, depending on the size of the fluorescent display tube or the spacing between each electrode, the dimensions of the projection 20 and the spacing from the filament 18 can be determined in various ways. For example, the spacing from the filament 18 is 0.1 mm. It can be set in the range of ~0.5mm.

Further, although the embodiments described above are statically driven fluorescent display tubes, the present invention can also be applied to dynamically driven fluorescent display tubes. In this case, the protrusion 20 may be provided at one or more locations on the spacer frame of an appropriate control electrode.

Note that in a dynamically driven fluorescent display tube, the protrusions may exhibit a negative potential depending on the time-division signal applied to the grid, but in this case, the anode display section facing the control electrode does not display a negative potential. Since no signal is given, problems such as broken characters do not occur.

[Effect of idea]

As explained above, in the present invention, in a fluorescent display tube having a triode structure, the protrusion filament is disposed on the upper surface of the grid or its holding part in close proximity to the protrusion filament, which is made of low-melting frit glass as the main component and contains a conductive material. In this case, the protrusion is not charged with static electricity, and vibration of the filament can be effectively prevented, and especially in high-brightness tubes, flickering due to fluctuations in brightness during operation can be reduced. Further, there is an effect that display chipping due to static electricity charge of the protrusion can be prevented. In addition, according to the present invention, even if the grid is thermally deformed, the distance between the filament and the grid can be maintained at a predetermined value, so it is possible to create a highly reliable fluorescent display tube that can reliably prevent thermal runaway. It has the effect of being able to obtain Furthermore, compared to conventional fluorescent display tubes, the present invention has the effect of reducing costs because components such as dampers and mounting fittings can be omitted.

Furthermore, in the present invention, if the projections are formed using a paste mainly composed of low-melting fritted glass, it is possible to use a forming and arranging means such as printing, so that the projections can be easily provided in multiple locations and This has the effect that the arrangement pattern of the sections can be freely set.

Furthermore, in the present invention, if the protrusion is arranged in a band shape in a direction perpendicular to the filament, it is possible to reliably support a plurality of filaments at one protrusion during vibration. There is.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway plan view of an embodiment of the present invention, Fig. 2 is a sectional view taken along the line - - in Fig. 1, and Fig. 3 is a main part showing the deformed state of the control electrode when thermal runaway occurs. 4 is a plan view of a main part of a conventional fluorescent display tube, and FIG. 5 is a sectional view taken along the line -- in FIG. 4. DESCRIPTION OF SYMBOLS 11...Substrate, 14...Anode conductor, 16...Spacer frame, 17...Grid, 18...Filament, 20...Protrusion.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An anode substrate covered with a phosphor, a control electrode disposed above the anode substrate, and a filament-shaped cathode disposed in a stretched manner above the control electrode. In the fluorescent display tube, a protrusion made of a low melting point fritted glass as a main component containing a conductive substance is disposed close to the filament cathode on the opposite surface of the control electrode or its holding part on the filament cathode side. A fluorescent display tube featuring (2) The fluorescent display tube according to claim 1 or 2, wherein the projection is arranged in a band shape in a direction perpendicular to the filament cathode.