JP2759803B2 - Fluorescent display tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fluorescent display tube using a plurality of linear indirectly heated cathodes. The present invention relates to an end connection structure of a linear indirectly heated cathode (hereinafter, abbreviated as an indirectly heated cathode) in the case where the cathode is composed of more than two thin metal wires.

(Prior art)

The conventional indirectly heated cathode has a four-layer structure in which a heater core wire, an insulating layer coated on the surface, a conductive layer formed on the insulating layer surface, and an electron emission layer coated on the surface of the conductive layer. It was a laminate. And it is divided into the following two types according to the structure of the conductive layer.

A. An indirectly heated cathode in which a conductive layer forms a metal film of Ni, W, etc. on the surface of an insulating layer, and is formed of a pipe-shaped conductive layer.

B. An indirectly heated cathode having a conductive layer formed by winding a thin metal wire such as W or Ni on the surface of the insulating layer.

Since the metal film of the pipe-shaped conductive layer is thin and easily peeled off, connection with a cathode terminal cannot be easily performed by a connection method such as soldering, pressure welding, welding or the like, and the work is not easy.

In view of this, various indirectly heated cathodes, which are made of a thin metal wire with a conductive layer wound thereon and solve the above problems, have been devised and disclosed. (JP-A-62-188130, JP-A-62-206737, JP-A-62-206746) When such a conventional indirectly heated cathode is mounted on a fluorescent display tube, it is necessary to disclose the actual operating system disclosed in JP-A-63-18750. As shown in the figure, a common base metal support is provided by a metal plate inside a common core support that fixes each heater core, and a plurality of conductive metals, which are base metals of the indirectly heated cathode, are provided on the common base metal support. In this connection structure, the winding ends of the thin metal wires of the layers are electrically connected by pressing and contacting with each other, and the ends of the base metal support are extended outside the envelope as leads. And such a base metal support was provided near the left and right ends.

[Problems to be solved by the invention]

However, the above-mentioned mounting structure has the distinctive advantage that the end cool of the indirectly heated cathode is short and the display area is enlarged because the base metal support is provided on the left and right inside the cathode support. On the other hand, there is a problem that the display area becomes small because the base metal support becomes an obstacle.

In general, an indirectly heated cathode has an applied voltage about twice as large and a current also about twice as large as a directly heated cathode. That is, compared with the supplied power, the supplied power must be added about four times as much. As described above, the indirectly heated cathode has a larger wire diameter than the directly heated type, and thus the supply power is increased in order to make the surface temperature of the indirectly heated cathode 650 ° C., which is the electron emission temperature. I will. It is a well-known fact that a large amount of heat is generated when the supplied power is large, and the end-cooling is shortened even in a conventional direct-heated cathode. Therefore, the indirectly heated cathode has less end-cooled portions than the directly heated cathode, and the display area is enlarged accordingly.

However, in the above-described mounting structure, the effect of enlarging the display area has not been sufficiently obtained due to the structure of the base metal support. Further, since the core wire support and the base metal support were common, it was not possible to control the indirectly heated cathode individually. Further, the heater core wires could not be connected in series.

Accordingly, an object of the present invention is to provide a fluorescent display tube having a mounting structure of an indirectly heated cathode capable of solving the above problems and sufficiently expanding a display area.

[Means for solving the problem]

In order to achieve the above-described object, the present invention provides a flat box-shaped envelope formed by sealing a substrate, a side plate, and a flat plate, and disposing an anode coated with a phosphor on the substrate, A fluorescent display tube having a plurality of linearly indirectly heated cathodes in which a heater core wire, an insulating layer, a wound thin metal wire, and an electron emission layer are stacked on the anode, Are stretched on a core support provided independently on the substrate, and the ends of the thin metal wires are arranged in the same row as the core support, thereby adjoining each core support on the substrate end side. It is characterized by being connected to an independent cathode terminal which is positioned as follows.

(Operation)

Since the present invention is configured as described above, the heater voltage is applied to the heater core from the core support, and the cathode terminal is connected to the thin metal wire forming each conductor layer. Is applied to drive the fluorescent display tube.

[Embodiment 1] FIG. 1 is an exploded perspective view of a fluorescent display tube according to a first embodiment of the present invention, and FIG. 2 is an enlarged perspective view of the indirectly heated cathode of the first embodiment. FIG. 4 is an enlarged plan view of a main part showing a mounting structure of the indirectly heated cathode shown in FIG. 1, and FIG. 4 is an enlarged sectional view of a waist showing the same structure.

In the figure, reference numeral 1 denotes a substrate, and a side plate 18 and a flat plate 19 described later constitute a box-shaped envelope. On this substrate 1, a wiring conductor 2 and an anode conductor 3 made of a metal thin film, for example, an Al thin film are formed in a pattern by means of photolithography.
The wiring conductor 2 and the anode conductor 3 may be formed in a thick film pattern by a screen printing method using an Ag paste or the like.

A phosphor layer 4 is applied on the anode conductor 3 by a well-known electrodeposition method, a printing method, or the like.

Further, an insulating layer 6 is provided on the substrate 1 except for the wiring conductor 2 and the anode 5, and covers the Al wiring. In addition, a frit glass solder 7 for sealing the side plate 18 is printed on the substrate 1 as is well known.

Above the anode 5 of the substrate 1, a control electrode 8 is provided. The control electrode 8 has a mesh grid 8a and a mounting portion 9 integrally formed, and the mounting portion 9 is fixed to the substrate 1 with a conductive adhesive. In the case of a fluorescent display tube driven by static electricity or a light source utilizing the principle of the fluorescent display tube, the control electrode 8 is omitted.

Next, as shown in FIG. 2, the indirectly heated cathode 10 comprises a heater core 11 made of a thin tungsten metal wire,
Insulating layer 12 of alumina coated around
And at least one or more tungsten thin metal wires 13 wound around the insulating layer 12 and an electron emission layer 14 coated around the thin metal wires 13.

Both ends of the heater core wire 11 are welded and fixed in a state where tension is applied to a core wire support member 15 formed by pressing a metal plate near both ends of the substrate 1. This core support 15
As shown in FIG. 3 or FIG. 4, each of the core support members comprises a spring portion 15b which rises from the lead portion to a lead portion 15a in contact with the substrate, and a welded portion 15c at the tip thereof. Are arranged in the direction of the core wire of the substrate 1 and extend to the back surface, form a U-shape, fit with the substrate, and are adhered and fixed with the frit glass solder 7 to constitute the heater terminal 15d. .

The end of the thin metal wire 13 is connected to a cathode terminal 16 formed of a metal plate in the same direction on the side of the core wire support 15. The tip of the cathode terminal 16 is
It is located in the same row as 15 or thereby on the substrate end side.

Further, the other end of the cathode terminal 16 extends as it is, and penetrates the sealing portion of the envelope in an airtight manner to form an external cathode lead 16a.

As described above, the core wire support 15 and the cathode terminal 16 are disposed substantially in parallel to the direction in which the indirectly heated cathode 10 is stretched, and the ends of the core support 15 and the cathode terminal 16 also extend outside the envelope in the same direction. A terminal 15a and an external cathode lead 16a are provided.

Next, a spacer frame 17 provided with a lead terminal 17a connected to the control electrode 8 and the anode 5 is placed on the substrate 1 configured as described above, and a container including a side plate 18 and a flat plate 19 is placed. The portion 22 is covered and sealed, and formed into a flat box shape.

The inside of the flat box-shaped envelope is evacuated from the exhaust pipe 21 provided in the side plate 18 to a high vacuum state to seal the exhaust pipe 21 to form a fluorescent display tube. .

The thus formed fluorescent display tube of the present invention has a heater terminal 15a connected to the heater core wire 11 of each indirectly heated cathode and an external cathode lead 16a connected to the thin metal wire 13, so that the heater core wire is provided. It is also possible to connect 15 in series externally or in parallel. Also, each metal wire
13 may be connected in parallel to apply the same cathode voltage, or may or may not apply a cathode voltage to individual conductive layers.

Furthermore, it is easy to test the fluorescent display tube, for example, to check the insulation state between the thin metal wire 13 and the heater core wire 11 and to check the disconnection and the resistance value of the thin metal wire 13 for each indirectly heated cathode. The characteristics of the pipe can be understood in detail.

Second Embodiment Next, a second embodiment shown in the exploded perspective view of FIG. 5 will be described.

In this embodiment, the indirectly heated cathode 10 is attached to a core support 15 and a cathode terminal 16 provided on a flat plate facing a substrate.

At both ends of the flat plate 19, core wire supports 15 made of a metal plate for fixing the core wire 11 of the indirectly heated cathode 10 are arranged. The indirectly heated cathode 10 is stretched and fixed to the core support 15 with tension applied thereto.

A cathode terminal 16 made of a metal plate is provided on the flat plate 19 on the side of the core wire support 15, and the tip of the thin metal wire 13 is connected thereto.

The mounting method of the core wire support 15 and the cathode terminal 16 and the arrangement positional relationship are the same as those in the first embodiment, and therefore the description thereof is omitted.

A flat box-shaped fluorescent display tube is formed by sealing the side plate 18 assembled in a frame shape on the flat plate 19 on which the indirectly heated cathode is disposed, and the substrate 1 on which the anode 5 and the control electrode 8 are disposed. Is formed.

After the sealing, the gas in the envelope is exhausted from the exhaust pipe provided on the flat plate, and the exhaust pipe is sealed when a high vacuum state is established. The anode 5, the insulating layer 6,
Since there is no control electrode 8 or the like, there is a feature that the indirectly heated cathode 10 can be easily mounted automatically.

Third Embodiment Next, a third embodiment shown in FIGS. 6 and 7 will be described.

In this embodiment, the cathode terminal 16 is provided on the substrate 1 with a conductive film.

Although the wiring conductor 2 and the anode conductor 3 are formed of a thin film or a thick film on the substrate 1 in the first embodiment, similarly, the pattern of the cathode terminal 16 is formed of a metal thin film or a conductive thick film. The insulating layer 6 is covered except for the terminal portion 16a at the tip of the cathode terminal 16 so as to appear. And the terminal section
The end of the thin metal wire 13 is bonded and fixed to 16a with a conductive adhesive.

Further, there may be an embodiment in which the cathode terminal 16 has a conductive film provided on a flat plate instead of a substrate.

Embodiment 4 Next, a fourth embodiment shown in a plan view of a main part in FIG. 8 and a sectional view in FIG. 9 will be described.

In this embodiment, the cathode terminal 16 is constituted by an external cathode and a wiring conductor made of a conductive film, and a cathode support made of a metal plate. That is, the cathode support 24 made of a metal plate is bonded and fixed to the terminal 16a of the third embodiment with the conductive adhesive 23. The thin metal wire 13 is connected to the cathode support 24 by soldering or welding.

Note that the present invention is not limited to the embodiments described above.For example, when an indirectly heated cathode is provided in a graphic fluorescent display tube, a strip anode coated with a phosphor, and the strip anode With the indirectly heated cathode disposed in the crossing direction, a graphic fluorescent display tube having a diode structure constituting a matrix structure can be considered. In such an embodiment as well, the indirectly heated cathode mounting structure of the present invention enables the control of the emission from the cathode by the voltage applied to the conductive layer because the cathode terminals 16 are individually independent. .

(Effect)

As described above, the fluorescent display tube of the present invention has the same thin metal wire as the core wire support, thereby stretching a plurality of wound indirectly heated cathodes provided on the end side of the substrate, and wrapping each thin metal wire. Since the structure is such that the heater core wires are electrically independent from each other while being connected to the cathode terminal, the following effects are obtained.

(1) Since the end cool of the indirectly heated cathode is shorter than the end cool portion of the directly heated cathode, the fluorescent display tube of the mounting structure of the present invention was formed to take advantage of this feature. Therefore, in the fluorescent display tube of the present invention, the display area is enlarged from both elements of the end cool part and the mounting part as compared with the conventional display area.

(2) After preparing the fluorescent display tube, check the insulation state between the conductive layer of the indirectly heated cathode and the heater core wire, and measure the disconnection and the resistance of the conductive layer for each indirectly heated cathode. be able to.

(3) The connection method of the heater core wires can be either serial or parallel.

(4) The cathode voltage can be controlled for each indirectly heated cathode.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a first embodiment of the fluorescent display tube of the present invention, FIG. 2 is an enlarged perspective view of the indirectly heated cathode of FIG.
FIG. 4 is an enlarged plan view of a main part showing a connection structure of the indirectly heated cathode of FIG. 1, FIG. 4 is an enlarged sectional view of a main part showing a connection structure of the indirectly heated cathode of FIG. 1, and FIG. Second embodiment of the fluorescent display tube of the present invention
FIG. 6 is an exploded perspective view of the embodiment, FIG. 6 is a plan view of a main part of a third embodiment of the fluorescent display tube of the present invention, FIG. 7 is a cross-sectional view of the main part of the embodiment, and FIG. FIG. 9 is a plan view of a main part of a fourth embodiment of the fluorescent display tube of the present invention, and FIG. 9 is a sectional view of the main part of the fourth embodiment. DESCRIPTION OF SYMBOLS 1 ... Substrate, 4 ... Phosphor layer 5 ... Anode, 10 ... Indirectly heated cathode 11 ... Heater core wire, 12 ... Insulating layer 13 ... Conductor layer (thin metal wire), 14 ... Electron emission layer 15 core support, 16 cathode terminal 16a external cathode lead, 18 side plate 19 flat plate, 24 cathode support

Claims (1)

(57) [Claims] An anode on which a phosphor is applied is disposed on a substrate in a flat box-shaped envelope formed by sealing a substrate, a side plate, and a flat plate, and a heater core wire is attached to the anode. A fluorescent display tube having a plurality of linearly indirectly heated cathodes in which an insulating layer, a wound thin metal wire, and an electron emission layer are laminated, wherein each of the heater core wires of the linearly indirectly heated cathode is a substrate. The metal wire support is stretched on a core wire support that is independently disposed on the upper side, and the end of the thin metal wire is the same as the core wire support or, thereby, is located adjacent to each core wire support on the substrate end side. A fluorescent display tube connected to the cathode terminal.