JP2007335269A - Vacuum fluorescent tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum fluorescent tube capable of improving reduction in the size and thickness and improving vibration resistance. <P>SOLUTION: The vacuum fluorescent tube is provided with a box-shaped ceramic case 2 formed to be an approximately rectangular parallelepiped; a band-shaped cathode 3 provided in a bottom part of a space inside the case 2; an anode which is provided in the upper part of the case 2 so as to seal it and comprises plate glass 7 having an electrical conductive film 18 inside and a phosphor 6 inside the electrical conductive film 18; a grid electrode 5 provided in an approximately intermediate part between the bottom and upper parts; and a shelf 4 formed to hold the grid electrode 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electron collision type vacuum fluorescent tube that emits light by colliding electrons emitted from a cathode electrode with a phosphor layer on an anode electrode, and more particularly to a vacuum fluorescent tube excellent in vibration resistance.

A conventional vacuum fluorescent tube used for a backlight of a liquid crystal display device, for example, forms a void layer between two glass substrates as in a “planar light emitting device” as disclosed in Patent Document 1. The transparent electrode serving as the anode and the phosphor coating are formed on the inner surface of the light irradiation side substrate, while the filament serving as the cathode is arranged in the line direction and wired on the inner surface of the back side substrate.
Thus, what employs a filament as a cathode is stretched linearly in a vacuum space, and a voltage is applied to both ends to emit thermoelectrons and collide with the phosphor coating to emit light. .

Patent Document 2 discloses “a backlight of a liquid crystal display device and a vacuum fluorescent tube therefor” filed by the applicant of the present application.
The present invention is also used as a backlight in the same manner as the invention disclosed in Patent Document 1, but in the present invention, a vacuum fluorescent tube is formed in a transparent cylindrical shape, and a cathode filament is formed in the central portion thereof. Arranged.
This is because, for example, in the case of a backlight used in a small liquid crystal display device such as a cellular phone, downsizing is required. In the case of the invention disclosed in Patent Document 1, the vacuum fluorescent tube is flat on the plane. For this reason, it is necessary to increase the thickness of the two glass substrates for maintaining the vacuum state, or because it is a flat surface, it is difficult to emit light uniformly over the entire flat surface.
In the invention disclosed in Patent Document 2, since the outer diameter can be suppressed to 3 mm or less, there is an effect that it greatly contributes to downsizing and thinning of the backlight. Furthermore, the excellent effect that the cost is low and the manufacturing operation is relatively easy can be exhibited.

Further, as an invention disclosed in Patent Document 3, this is also filed by the applicant of the present application, and there is one whose name is “vacuum fluorescent tube and manufacturing method thereof”.
In the invention disclosed in Patent Document 3, a semi-cylindrical half pipe and a flat base plate are joined to form a vacuum fluorescent tube. The indium / tin oxide film (hereinafter referred to as ITO film) formed as an anode on the inner surface of the vacuum fluorescent tube in Patent Document 2 is difficult to apply on the cylindrical inner surface, and the manufacturing cost is high and the yield is poor. There was a problem.
Therefore, a half pipe capable of easily forming an ITO film is employed. In the invention disclosed in Patent Document 3 configured by joining the half pipe and the base plate in this manner, the manufacturing cost and the yield are improved, and since it is a semi-cylindrical shape, it is more than the cylindrical shape of Patent Document 2. Furthermore, the effect that thickness reduction was attained was acquired.
JP 2000-200050 A JP 2005-44640 A JP 2006-120447 A

However, the vacuum fluorescent tube disclosed in Patent Document 3 as described above is also required to be small and thin when used in a mobile tool such as a mobile phone that is always carried by a user. There was a problem of vibration resistance. Each of the inventions disclosed in Patent Documents 1 to 3 is equipped with a filament that generates thermoelectrons as a cathode, and in the case of a long filament wire, there is a possibility of contact with the anode during use. There was a possibility of causing damage or malfunction. Of course, it is possible to absorb the vibration to some extent by the tension generators provided at both ends in order to stretch the filament wire, but the tension force is generated as the filament wire becomes longer. There is a problem that the mechanism becomes large and miniaturization cannot be achieved.
According to the investigation by the present inventor, when the length is about 50 mm, the necessary tension is 6 gram weight, and the tensioner which is a mechanism for generating the tension force at this time can be manufactured with a metal part of about 2 mm. It was. However, when the filament length is 100 mm, the tension is required to be 12 grams or more. In this case, the size of the tensioner exceeds 5 mm and is often mounted in a very small space. For example, a backlight of a mobile phone However, there is a problem that an increase in dead space that does not contribute to light emission is extremely inconvenient.

  The present invention has been made in view of such conventional circumstances, and an object of the present invention is to provide a vacuum fluorescent tube capable of improving vibration resistance as well as improvement in size and thickness.

In order to achieve the above object, a vacuum fluorescent tube according to claim 1 is a box-shaped container formed in a substantially rectangular parallelepiped made of ceramic, a strip-shaped cathode electrode provided at the bottom of the space in the container, An anode electrode is provided to seal the container at the upper part of the container and is formed of a plate-like glass having an electric conductor film on the inner side and a phosphor on the inner side. It has a grid electrode and a shelf formed to hold the grid electrode.
In the vacuum fluorescent tube configured as described above, a strip-shaped cathode electrode is provided at the bottom of the space in the container in place of the cathode filament provided at the center of the vacuum fluorescent tube. There is no contact, and there is no need to provide a tensioner for stretching. Most of the electrons emitted from the cathode by the electric field applied by the voltage applied to the grid pass through the grid and reach the anode. In addition, the shelf that holds the grid electrode acts to firmly hold the grid electrode and enhance the vibration resistance of the grid electrode.

According to a second aspect of the present invention, there is provided a vacuum fluorescent tube according to the first aspect of the present invention, wherein the cathode electrode, the anode electrode, and the grid electrode are each provided with an external electrode outside the container. It is connected to the electrode via an inner layer wiring provided inside the container.
In the vacuum fluorescent tube configured as described above, the inner layer wiring acts so as to connect each electrode and the external electrode. Further, by providing the inside of the container, it acts so that external wiring can be eliminated and a smaller package can be realized.

Furthermore, a vacuum fluorescent tube according to a third aspect of the present invention is the vacuum fluorescent tube according to the first or second aspect, wherein the space in the container is provided with a getter.
In the vacuum fluorescent tube having the above-described configuration, when the vacuum fluorescent tube is manufactured, the getter is activated and has an action of adsorbing and removing the gas in the container space.

According to a fourth aspect of the present invention, there is provided the vacuum fluorescent tube according to the third aspect, wherein the getter is placed on a getter fixing pad formed of an electric conductor, and the inner layer wiring of the anode electrode is the anode electrode. The external electrode and the getter fixing pad are connected, and the getter fixing pad and the anode electrode are connected by an electric conductor piece in the space in the container.
In the vacuum fluorescent tube configured as described above, the getter fixing pad on which the getter is placed and the electric conductor piece act as the anode electrode contact pad. An anode electrode composed of a glass sheet with an electrical conductor film on the inside and a phosphor on the inside is provided on the top of the container, so it is difficult to wire the inner layer wiring from the external electrode of the anode electrode so far Using the getter fixing pad provided in the inner space of the container, the inner layer wiring is used up to the getter fixing pad in the middle, and then the electric conductor piece is stood in the inner space of the container so as to connect to the getter fixing pad and the anode electrode. It acts on.

A vacuum fluorescent tube according to a fifth aspect of the present invention is the vacuum fluorescent tube according to the second or third aspect, wherein instead of the external electrode and the inner layer wiring of the anode electrode, a plate-like glass constituting the anode electrode is used. An electric conductor film is further extended from the side end surface of the container, and the electric conductor film formed outside the container is used as an external electrode.
In the vacuum fluorescent tube configured as described above, an anode electrode is extended to the outside so as to act as an external electrode. There is no need to provide inner layer wiring.

In the vacuum fluorescent tube according to claim 1 of the present invention, it is not necessary to stretch the cathode filament with a tensioner, and therefore it is possible to provide a vacuum fluorescent tube having excellent vibration resistance. Further, by providing the grid electrode holding shelf, it is possible to enhance the vibration resistance of the grid electrode and sufficiently achieve downsizing and thinning as a whole, while also exhibiting vibration resistance.
Furthermore, by providing a holding shelf, the distance from the cathode electrode can be stably maintained constant.

  Further, in the vacuum fluorescent tube according to claim 2 of the present invention, in addition to the effect of the invention according to claim 1, the inner layer wiring connects each electrode and the external electrode and is packaged by eliminating the external wiring. As a result, mass production is facilitated, the manufacturing process is simplified and the efficiency is increased, and the vacuum fluorescent tube itself can be saved in space.

  In the vacuum fluorescent tube according to claim 3 of the present invention, in addition to the effect of claim 1 or 2, when the vacuum fluorescent tube is manufactured, the degree of vacuum of the space in the container is made higher. It is possible to provide a vacuum fluorescent tube with high luminous efficiency and excellent durability.

  In the vacuum fluorescent tube according to claim 4 of the present invention, by removing a part of the inner layer wiring connecting the anode electrode and the external electrode, the getter fixing pad is also used as the anode electrode contact pad, so that the electric conductor piece is The complexity of the inner layer wiring can be eliminated by connecting the anode electrode to the space in the container. In addition, effective utilization of the space in the container and simplification of the structure of the vacuum fluorescent tube can be promoted.

  In the vacuum fluorescent tube according to claim 5 of the present invention, since the anode electrode is extended to the outside and used as the external electrode, the inner layer wiring or the electric conductor piece is provided in the space in the container for the anode electrode. The structure of the vacuum fluorescent tube can be further simplified as compared with the vacuum fluorescent tube described in claim 4. However, since the external electrode exists on the extension of the anode electrode, it is generally considered that it is separated from the position of the cathode electrode and the grid electrode, and the wiring with the power source connected to the external electrode may be complicated. There is.

Hereinafter, a vacuum fluorescent tube according to the best mode of the present invention will be described with reference to FIGS.
FIG. 1 is a conceptual diagram of a vacuum fluorescent tube according to an embodiment of the present invention. 2A is a cross-sectional view of the vacuum fluorescent tube according to the present embodiment, FIG. 2B is a cross-sectional view showing a modification of the grid, and FIG. 2C is a cross-section showing a modification of the anode glass. FIG.
In FIG. 1, a vacuum fluorescent tube 1 is formed in a substantially rectangular parallelepiped box shape, and the inside thereof is a base plate 2 as a container formed in a concave shape with a cross section perpendicular to the longitudinal direction, and a transparent covering the base plate 2 like a lid. A carbon nanotube 3 is provided as a cathode electrode through a cathode fixing pad (not shown) on the bottom surface of a groove portion 9 provided with an anode glass 7 and formed in the inner space of the base plate 2. A grid holding shelf 4 is formed above the groove portion 9 of the base plate 2 on which the carbon nanotubes 3 are arranged. The grid holding shelf 4 has a grid 5 as a grid electrode via a grid fixing pad (not shown). Is formed so as to cover the carbon nanotubes 3.
On the other hand, as an anode electrode, an ITO film (not shown) is formed on the lower surface of the anode glass 7, and a phosphor 6 is applied to form a film on the lower surface, that is, the inner space side of the base plate 2. .
A getter 8 is disposed at the inner end of the base plate 2. The getter 8 is a variety of types that activates the upper portion of the base plate 2 with the anode glass 7 and then irradiates an infrared beam or the like from the outside of the vacuum fluorescent tube 1 to lower the vacuum degree of the vacuum fluorescent tube 1. The gas is arranged for the purpose of adsorbing the gas and improving the degree of vacuum. As this getter 8, for example, a sintered body containing Zr as a main component and containing Al or the like can be employed.

Next, the vacuum fluorescent tube 1 according to the present embodiment will be described in detail with reference to FIG. In FIG. 2A, as described with reference to FIG. 1, a cathode fixing pad 11 made of an electric conductor is formed at the groove bottom of the space in the base plate 2 of the vacuum fluorescent tube 1, and this cathode fixing pad is formed. The carbon nanotubes 3 are applied so as to come into contact with 11. The carbon nanotube 3 may be applied by using an electrodeposition method, a dispenser application, an ink jet method, or the like. In this case, the electric conductor is preferably silver-based thick film printing, and is preferably used after being plated with nickel, for example.
Alternatively, as another means, a thin metal plate is used as a substrate, and the carbon nanotubes 3 are coated on the groove width and subjected to a predetermined heat treatment, and then cut into a groove bottom portion of the space in the base plate 2. The cathode electrode can be formed by housing and electrically connecting the groove bottom electrode with a technique such as welding.
The cathode fixing pad 11 is connected to a cathode external electrode 12 provided outside the base plate 2 via a cathode inner layer wiring 13.

On the other hand, in the inner space of the base plate 2, grid holding shelves 4 are provided along the longitudinal direction of the base plate 2 on both sides above the groove bottom, and the grid holding shelves 4 are the same as described above. A grid fixing pad 15 made of an electric conductor is placed along the longitudinal direction of the base plate 2. A grid 5 is provided so as to straddle the grid fixing pads 15 on both sides. The grid 5 is made of a metal mesh, welded to the grid fixing pad 15, and has strong resistance to vibration of the base plate 2. The metal mesh is preferably formed by using a technique such as etching with a thin metal plate (approximately 20 to 50 μm) having an opening diameter of 100 μm and an opening ratio of about 75%. In addition to etching, electroforming (electroforming) or the like can also be employed.
The grid fixing pad 15 is also connected to a grid external electrode 16 provided outside the base plate 2 via a grid inner layer wiring 17.

Here, a description of the structure of the base plate 2, the cathode inner layer wiring 13, and the grid inner layer wiring 17 will be added.
The base plate 2 is made of low temperature co-fired ceramic (LTCC), and a plurality of green sheets having a thickness of about 0.1 mm are stacked to a temperature of about 850 ° C. (normal ceramic firing). It is created by firing at a temperature lower than the temperature. Low-temperature co-fired ceramics have a very low shrinkage ratio during firing, and are used for the formation of electronic circuit boards. Wirings necessary for circuit formation can be formed between the respective layers, and conduction between the wirings can be established through via holes penetrating each layer.
In addition, since the base plate 2 is made of LTCC, the height of the grid holding shelf 4 can be freely changed to a height of several millimeters in increments of 0.05 mm in the LTCC manufacturing process. In addition, an appropriate height can be easily selected.
The grid 5 of the vacuum fluorescent tube 1 according to the present embodiment can be manufactured by using an industrially easy and inexpensive means such as an etching mesh. The grid 5 manufactured with an etching mesh or the like is mechanically very weak because it needs to be made very thin, and the area covering the light emitting surface to which the phosphor 6 is applied must be kept at a uniform height. Usually, an insulator such as glass is laid and fixed on it, but there is a limit to downsizing in terms of structure in order to pull out to the outside while maintaining electrical continuity. Therefore, in the present embodiment, the LTCC is adopted, the grid holding shelf 4 is formed while the thin green sheets are stacked, and the very thin grid 5 is placed and fixed thereon. The area covering the light emitting surface can be maintained at a uniform height with high accuracy and can be formed extremely compact.
Furthermore, the height from the grid 5 to the anode electrode (ITO film 18) can be freely selected from several millimeters in increments of 0.05 mm, and the current density obtained from the carbon nanotubes 3 and the phosphor applied to the ITO film 18 The optimum height can be easily formed by the six types.

In FIG. 2, LTCC that has already been baked at a low temperature by stacking a plurality of green sheets is formed as a base plate 2, and inside of the cathode inner layer wiring 13 and grid inner layer wiring 17 are wired via via holes (not shown). The cathode external electrode 12 and the cathode fixing pad 11, and the grid external electrode 16 and the grid fixing pad 15 are connected to each other.
The relationship between the inner layer wiring and the plurality of green sheets will be described later with reference to FIGS.
On the upper side of the base plate 2, an anode glass 7 is provided as an anode electrode by applying an ITO film 18 on the inner space side of the base plate 2. The phosphor 6 is applied to the surface of the ITO film 18 on the space side in the base plate 2. The phosphor 6 may be applied by a printing method, an electrodeposition method, an ink jet method, a precipitation method, or the like.
The anode glass 7 extends outward from the side surface of the base plate 2, and the ITO film 18 extends along with the anode glass 7. The portion extending outside is used as the anode external electrode 14, and the vacuum fluorescent tube 1 is sealed in such a state.
In the vacuum fluorescent tube 1 according to the present embodiment configured as described above, the anode made of anode glass formed by applying the carbon nanotube 3 as the cathode electrode, the grid 5 as the grid electrode, and the ITO film 18 from the bottom side. Although it is configured as an electrode, when considering connection to an external power supply, an inner layer wiring is provided inside the base plate 2 and the external electrode provided on the outer bottom of the base plate 2 is connected to the electrode provided therein. Therefore, it is desirable to reduce the complexity of the wiring provided around the vacuum fluorescent tube 1 as much as possible and to improve the durability of the wiring.

However, since the anode electrode is provided on the upper part of the base plate 2, the side surface of the base plate 2 must be formed thick in order to properly perform the inner layer wiring, and be aligned with other external electrodes. When the anode external electrode is provided on the outer bottom portion of the base plate 2, the distance between the ITO film 18 provided on the upper portion and the anode electrode made of the anode glass 7 becomes long, and the manufacturing process becomes complicated. Therefore, in the present embodiment, the anode glass 7 coated with the ITO film 18 is further extended from the side surface of the base plate 2, and the portion exposed from the side surface of the base plate 2 is used as the anode external electrode 14.
By using such an anode external electrode 14, although it is provided in a location away from the cathode external electrode 12 and the grid external electrode 16, it is not necessary to form an inner layer wiring inside the base plate 2, and productivity is improved. It is quite expensive and effective from an economic aspect.
In the vacuum fluorescent tube according to the present embodiment shown in FIG. 2A, electrons emitted from the cathode fixing pad 11 through the carbon nanotube 3 are generated on the grid 5 formed so as to cover the carbon nanotube 3. Released by the applied voltage.
In the first place, the electron emission from the carbon nanotube 3 depends on the electric field applied to the tip of the carbon nanotube 3, but the vacuum fluorescent tube 1 according to the present embodiment is a so-called triode having a grid 5. The electric field applied to the tip of the electrode can be made larger by the applied voltage by the grid 5 closer to the anode electrode. In general, the electron emission of the carbon nanotube 3 requires a voltage of 1 to 5 V / μm in order to obtain a practical luminance. However, there is a manufacturing dimensional error or material unevenness between the anode electrode and the cathode electrode. In consideration of this, it is unavoidable to be about 1 mm, and in this case, a sufficient applied voltage cannot be obtained at the tip of the carbon nanotube 3. Therefore, a grid 5 is provided between these electrodes, and a large electric field is generated in the carbon nanotube 3 by an applied voltage of the grid 5.
Electrons emitted through the carbon nanotubes 3 are accelerated toward the anode electrode according to the electric field formed in the space inside the vacuum fluorescent tube 1 and collide with the phosphor 6. The phosphor 6 is excited by the collision of electrons and emits light.

Next, the grid shown in FIG. 2B will be described. In the grid 5a shown in FIG. 2B, the cross-sectional shape has a dome shape. In this figure, a cross section perpendicular to the longitudinal direction of the vacuum fluorescent tube 1 is shown, but this cross-sectional dome shape is formed continuously in the longitudinal direction of the vacuum fluorescent tube 1.
In such a grid 5a, the cross-section of the grid 5a can be curved so that electrons spread through the grid 5a can be spatially spread, and this causes an electron collision to the phosphor 6 in a wider range. In addition, the light emitting area can be expanded.
Further, the anode glass shown in FIG. 2C will be described. The anode glass 7a is formed in a mountain shape with an upper surface provided with a flat surface at a substantially central portion, and a descending slope is provided from the central portion toward the side surface side of the base plate 2, and the cross-sectional shape thereof is shown in FIG. ).
By setting it as such a shape, the brightness | luminance in the flat surface of a substantially center part can be improved. The shape of the substantially central portion of the upper surface is not limited to the mountain shape, and may be a parabolic shape that is convex upward.

Next, the structure of the base plate will be described with reference to FIGS. FIG. 3 is an exploded view of the base plate of the vacuum fluorescent tube 1 shown in FIG. 2 (a). Since the anode external electrode is provided as an extension of the anode glass 7 and the ITO film 18, the bottom portion of the base plate is shown. Although not provided on the lower surface of the base plate, the base plate shown in FIG. 4 is provided on the lower surface together with the cathode external electrode and the grid external electrode.
The base plate 2 shown in FIG. 3 and the base plate 2a shown in FIG. 4 are both made of LTCC obtained by stacking a plurality of thin ceramic sheets called green sheets and firing them at a low temperature as described above. In the base plates 2 and 2a according to the present embodiment, the uppermost layer is the first green sheet 26a and the lowermost layer is the sixth green sheet 26f, and each is configured by stacking six green sheets 26a to 26f. Has been.
In the first green sheet 26a, getter fixing pads 27 are provided at two positions on both ends, and a grid fixing pad 15 is provided around the opening 22a. The second green sheet 26b is provided with an opening 22b having the same size as the opening 22a. In the third and fourth green sheets 26c and 26d, the sizes of the openings 22c and 22d are reduced. Yes. The openings 22a to 22d become the inner space of the vacuum fluorescent tube 1 when the green sheets 26a to 26f are fired, and there is a difference in size between the openings 22a and 22b and the openings 22c and 22d. This is the grid holding shelf 4 shown in the cross-sectional view of FIG.
In FIG. 3, the third to sixth green sheets 26c to 26f have wiring films 28c to 28f, the fifth green sheet 26e has a cathode fixing pad 11, and the sixth green sheet 26f has a wiring film 29. Further, a cathode external electrode 12 and a grid external electrode 16 are provided on the lower surface thereof.
Accordingly, the thickness of the five green sheets from the first green sheet 26a to the fifth green sheet 26e becomes the grid-cathode gap.

Further, in the base plate 2a shown in FIG. 4, wiring films 31c to 31f are further provided on the third to sixth green sheets 26c to 26f, and an anode external electrode 14a is provided on the lower surface of the sixth green sheet 26f. Yes.
These cathode external electrode 12, grid external electrode 16 and anode external electrode 14a are nickel alloys having a thickness of several tens of μm, or nickel plated or gold plated on the surface. Wiring can be connected.
The connection between these external electrodes and the electrodes provided in the space in the base plate 2 will be described.
First, the connection between the cathode fixing pad 11 and the cathode external electrode 12 will be described. The cathode fixing pad 11 is provided on the fifth green sheet 26e, and in order to connect it to the cathode external electrode 12 provided on the lower surface of the sixth green sheet 26f, first, the cathode fixing pad 11 and the sixth green sheet 26e are connected. The wiring film 29 formed on the upper surface of the green sheet 26f is connected through an electric conductor (not shown) embedded in a via hole formed through the fifth green sheet 26e. Then, the wiring film 29 formed on the upper surface of the sixth green sheet 26f and the cathode external electrode 12 provided on the lower surface of the sixth green sheet 26f are embedded in the via hole formed through the sixth green sheet 26f. By connecting via the electric conductor (not shown), the cathode fixing pad 11 and the cathode external electrode 12 are finally connected.
The wiring film 29 and the electrical conductor embedded in the via hole penetrating the fifth and sixth green sheets 26e and 26f are combined to form an inner layer wiring.

Next, the connection between the grid fixing pad 15 and the grid external electrode 16 will be described. As in the case of the cathode fixing pad 11 and the cathode external electrode 12, the grid fixing pad 15 formed on the first green sheet 26a and the wiring film 28c provided on the third green sheet 26c are formed on the first and second green sheets. Connections are made via electrical conductors (not shown) embedded in via holes formed through the sheets 26a and 26b. Similarly, the wiring films 28c to 28f are connected through electrical conductors (not shown) embedded in via holes formed through the green sheets 26c to 26e, respectively. Finally, a via hole formed through the sixth green sheet 26f with the wiring film 28f formed on the sixth green sheet 26f and the grid external electrode 16 provided on the lower surface of the sixth green sheet 26f. It connects via the electrical conductor (not shown) embedded in the.
In this case, the inner layer wiring includes the electric conductor embedded in the via hole formed through the first to sixth green sheets 26a to 26f and the wiring film formed on the upper surfaces of the third to sixth green sheets 26c to 26f. 28c to 28f.
Next, the connection between the anode external electrode 14a and the getter fixing pad 27 will be described with reference to FIG. In the vacuum fluorescent tube according to the present embodiment described so far, the anode glass 7 coated with the ITO film 18 is further extended from the side surface of the base plate 2 as the anode external electrode 14 so as to protrude outside the vacuum fluorescent tube 1. It was to utilize the part.
However, with this configuration, the anode external electrode 14 must be provided at a position different from the other cathode external electrode 12 and grid external electrode 16 as described above, and the wiring becomes complicated, or the side surface of the base plate 2 Therefore, when the vacuum fluorescent tubes 1 are arranged in parallel and used as a backlight, the vacuum fluorescent tubes 1 must be arranged apart from each other by the protruding anode external electrode 14. Therefore, the space efficiency may be deteriorated.

Therefore, in the base plate 2 shown in FIG. 4, the anode external electrode 14a is provided on the lower surface of the sixth green sheet 26f together with the cathode external electrode 12 and the grid external electrode 16, and the anode glass 7 is formed via the inner layer wiring. It is intended to be connected to the ITO film 18 formed on the lower surface.
However, as is clear with reference to FIG. 2, the side surface from approximately half to the upper part of the base plate in the vertical direction is different from the side surface on the lower side. Although it is thin as long as there is no problem in strength, it is difficult to provide the inner layer wiring inside the side surface from the viewpoint of productivity and accuracy.
Therefore, the getter fixing pad 27 for placing the getter 8 shown in FIG. 1 is made of a conductive, for example, metal or alloy pad, on the first green sheet 26a. The inner layer wiring for connecting the anode external electrode 14a provided on the lower surface of the green sheet 26f is applied, and the getter fixing pad 27 and the ITO film 18 provided on the anode glass 7 are connected by separate means. is there.
This separate means will be described later with reference to FIG. 5. Here, the inner layer wiring connecting the getter fixing pad 27 and the anode external electrode 14a will be described first.

In FIG. 4, the getter fixing pad 27 formed on the upper surface of the first green sheet 26a is the wiring formed on the upper surfaces of the third to sixth green sheets 26c to 26f as in the case of the grid external electrode 16. The films 31c to 31f and the first to sixth green sheets 26a to 26f are connected by the inner layer wiring constituted by the electrical conductors embedded in the via holes.
By using the base plate 2 formed by stacking and firing the green sheets 26a to 26f in this way, the inner layer wiring can be used, and the wiring related to the vacuum fluorescent tube 1 can be simplified, accurate, and durable. It is possible to improve.
In addition, what is described in the upper part of the 1st green sheet 26a shown by FIG.3, 4 is the upper side part 30 of the baseplates 2 and 2a. The manufacturing method is as described above, and is made of LTCC as in the lower part, and is manufactured by stacking and baking a plurality of thin grease sheets.
3 and 4, the gap indicated by ΔL is the anode-grid gap.

Next, description will be added to the base plate and other components of the vacuum fluorescent tube according to the present embodiment with reference to FIG. FIG. 5 is an exploded view of the vacuum fluorescent tube according to the present embodiment.
The carbon nanotube 3 connected to the cathode fixing pad is provided in the groove portion of the lower part of the base plate 2, and the grid 5 connected to the grid fixing pad 15 is placed on the grid holding shelf 4 on the upper part, and getters 8 are placed on both ends thereof. Arrange. Further, an anode glass 7 for forming the ITO film 18 on the lower surface is provided via the sealing frit glasses 24 and 25.
Here, a spring 23 formed of an electric conductor such as a metal or an alloy connected to a getter fixing pad (not shown) is provided on the upper portion of the getter 8, and an upper end portion of the spring 23 is formed on the anode glass 7. It is in contact with the ITO film 18 formed on the lower surface. That is, when the anode external electrode 14a is provided on the lower surface of the sixth green sheet 26f described with reference to FIG. 4, the getter fixing pad 27 and the anode electrode are connected via the spring 23 connected to the getter fixing pad. It is done. That is, by providing the spring 23 by utilizing the space of the getter 8 provided for improving the degree of vacuum in the space in the base plate 2 of the vacuum fluorescent tube 1, without providing the inner layer wiring inside the upper side surface of the base plate 2, The connection between the anode external electrode 14a and the anode electrode in the vacuum fluorescent tube 1, that is, the ITO film 18, is made possible.
In the vacuum fluorescent tube 1 configured as described above, the ITO glass 18 and the phosphor 6 film (not shown) on the lower surface side of the ITO film 18 are formed on the anode glass 7, and then the sealing frit glass 24 is attached to the anode glass 7. Then, after the sealing frit glass 25 is applied to the sealing surface on the side of the base plate 2 and assembled, the anode glass 7 and the base plate 2 are assembled together, and then this assembly is set to 400. By heating to ˜500 ° C., the sealing frit glasses 24 and 25 are melted and sealed. These operations are performed in a processing container that can be evacuated. When sealing with frit glass is completed, the vacuum fluorescent tube 1 is taken out of the processing container, and the getter 8 is irradiated with an infrared beam or the like as described above. Heating and activation are performed to improve the degree of vacuum in the inner space of the vacuum fluorescent tube 1.

Finally, an electric circuit of the vacuum fluorescent tube according to the present embodiment will be described with reference to FIG. FIG. 6 is an electric circuit diagram of the vacuum fluorescent tube. In FIG. 6, a cathode external electrode 12, an anode external electrode 14 a, and a grid external electrode 16 are provided on the lower surface side of the base plate 2. That is, the vacuum fluorescent tube 1 shown in the figure is of a type in which the anode external electrode 14a is provided at the bottom of the base plate 2a. The anode external electrode 14 a is applied by an anode power source 20, and a grid power source 21 that is a variable power source is provided for the grid external electrode 16. By applying a voltage to the grid by the grid power supply 21, the electric field of the cathode is increased and electrons are emitted. The voltage can be applied to the grid by performing pulse width modulation or switching at a high speed.
The emission luminance of the vacuum fluorescent tube 1 can be adjusted by adjusting the voltage applied to the grid power source 21 which is a variable power source. However, in practice, the pulse width modulation of the grid power source 21 is performed. In many cases, the luminance is adjusted, and the light emission can be stopped completely.
In this figure, the cathode external electrode 12, the anode external electrode 14a, and the grid external electrode 16 are clearly shown one by one. However, those indicated by white squares on the right side of the bottom surface of the base plate 2a are respectively the cathode external electrode 12 and the anode external electrode. By using the electrode 14a and the grid external electrode 16 as a pair, each external electrode is connected in parallel from each power source, and the inner layer wiring to the electrode inside the vacuum fluorescent tube 1 is also provided in a double manner. Redundancy may be provided so that a failure due to a single failure from the electrode to the inner layer wiring can be prevented. The exploded view shown in FIGS. 3 and 4 has such a redundancy.
Of course, one or more external electrodes and inner wirings may be provided in consideration of cost and productivity.

In the vacuum fluorescent tube 1 according to the present embodiment configured as described above, the cathode fixing pad 11 is provided in the groove portion 9 provided at the bottom of the base plates 2 and 2a, and the carbon nanotubes 3 are arranged on the upper surface thereof. A pair of grid holding shelves 4 are provided in the middle stage of the base plates 2 and 2a in parallel with the longitudinal direction of the vacuum fluorescent tube 1, a pair of grid fixing pads 15 are provided, and a grid 5 is provided so as to straddle the pair of grid fixing pads 15. And the ITO film 18 and the phosphor 6 are applied on the lower surface of the flat plate-like anode glass 7 to form an anode electrode, so that a thin linear filament stretched with tension at the center is provided. There is no need to provide it, and it can be configured thin with a simple structure. Therefore, it can be said that the structure is suitable when the mounting space is small. Further, when the light generated in the vacuum fluorescent tube 1 is taken out, the anode glass 7 has a flat plate shape. Therefore, the light guide plate can be directly adhered to the anode glass 7, and the most efficient light guide is possible.
Further, the base plates 2 and 2a are sealed with the anode glass 7, and the carbon nanotubes 3 provided in the inner space are coated and fired in a planar shape, and the grid 5 is firmly joined to the planar shape by welding or the like. In a strong vibration environment, the gap between the carbon nanotube 3 and the grid 5, and the gap between the grid 5 and the ITO film 18 can be kept constant, and is resistant to vibration. For liquid crystal screens used in mobile devices such as mobile phones. When used for a backlight or the like, it is useful as a device having excellent durability.
Furthermore, the carbon nanotube 3 as the cathode electrode, the grid 5 as the grid electrode, and the ITO film 18 as a part of the anode electrode are each formed in a planar shape, and the electric field can be maintained in a parallel planar shape. The geometric efficiency from the generation of electrons to the absorption is good, and therefore excellent characteristics can be exhibited as the vacuum fluorescent tube 1 having excellent emission luminance. It is possible to obtain an excellent light source having a long and narrow bar shape.
Further, by extending the anode glass 7 from the side surface of the base plate 2 with the ITO film 18 applied, the anode external electrode 14 can be formed. In this case, an anode external electrode is separately provided on the bottom surface of the base plate 2. Therefore, it is not necessary to provide the inner layer wiring inside the base plate 2.
Further, when external electrodes are arranged together on the bottom surface of the base plate 2, the getter fixing pad 27 is used as the inner layer wiring from the anode external electrode 14 a, and the getter fixing pad 27 to the ITO film 18 of the anode glass 7 are connected. By devising to connect with the spring 23, the anode external electrode 14a is arranged together with other external electrodes on the bottom surface of the base plate 2, and the inner layer wiring inside the side surface of the base plate 2 where inner layer wiring is difficult is avoided. It is also possible to effectively utilize the space inside the base plate 2.

  As described above, the invention described in claims 1 to 5 of the present invention includes various liquid crystal display devices such as a liquid crystal television and a monitor device, a mobile phone, a digital camera, a digital audio player, a telephone, and a facsimile. It can be used not only as a backlight but also as a light emitting device itself of a display device.

It is a conceptual diagram of the vacuum fluorescent tube which concerns on embodiment of this invention. (A) is sectional drawing of the vacuum fluorescent tube which concerns on this Embodiment, (b) is sectional drawing which shows the modification of a grid, (c) is sectional drawing which shows the modification of anode glass. It is an exploded view of the base plate of the vacuum fluorescent tube according to the present embodiment. It is an exploded view of the base plate which concerns on the other Example of the vacuum fluorescent tube which concerns on this Embodiment. It is an exploded view of the vacuum fluorescent tube which concerns on this Embodiment. It is an electric circuit diagram of the vacuum fluorescent tube according to the present embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vacuum fluorescent tube 2, 2a ... Base plate 3 ... Carbon nanotube 4 ... Grid holding shelf 5, 5a ... Grid 6 ... Phosphor 7,7a ... Anode glass 8 ... Getter 9 ... Groove part 11 ... Cathode fixing pad 12 ... Cathode external electrode DESCRIPTION OF SYMBOLS 13 ... Cathode inner layer wiring 14, 14a ... Anode external electrode 15 ... Grid fixed pad 16 ... Grid external electrode 17 ... Grid inner layer wiring 18 ... ITO film | membrane 20 ... Anode power supply 21 ... Grid power supply 22a-22d ... Opening 23 ... Spring 24, 25 ... Sealing frit glass 26a-26f ... Green sheet 27 ... Getter fixing pad 28c-28f ... Wiring film 29 ... Wiring film 30 ... Upper side part 31c-31f ... Wiring film

Claims (5)

  A box-shaped container formed in a substantially rectangular parallelepiped made of ceramic, a strip-shaped cathode electrode provided at the bottom of the space in the container, and an electric conductor film provided inside the container to seal the container at the top of the container It has an anode electrode composed of a sheet glass provided with a phosphor inside thereof, a grid electrode provided at a substantially middle portion between the bottom and the top, and a shelf formed to hold the grid electrode. A vacuum fluorescent tube characterized by   2. The cathode electrode, the anode electrode, and the grid electrode are provided with external electrodes on the outside of the container, respectively, and are connected to these external electrodes via an inner layer wiring provided inside the container. The vacuum fluorescent tube described.   The vacuum fluorescent tube according to claim 1 or 2, wherein a getter is provided in the inner space of the container.   The getter is placed on a getter fixing pad formed of an electric conductor, an inner layer wiring of the anode electrode connects an external electrode of the anode electrode and the getter fixing pad, and the getter fixing pad and the anode electrode are 4. The vacuum fluorescent tube according to claim 3, wherein the vacuum fluorescent tube is connected by an electric conductor piece in the space in the container.   Instead of the external electrode and the inner layer wiring of the anode electrode, a sheet glass and an electric conductor film constituting the anode electrode are further extended from the side end surface of the container, and the electric conductor film formed outside the container is provided. The vacuum fluorescent tube according to claim 2 or 3, wherein the vacuum fluorescent tube is an external electrode.