JPH1186788A - Planar discharge tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar discharge tube which has a small unluminous area to facilitate its manufacture. SOLUTION: In a planar discharge tube, constituting an airtight vessel containing electric discharge gas by two sheets of opposite squared surface plates, side surface plate for supporting a surface plate peripheral part, and a strut for supporting the surface plate in the inside of the vessel, a metal plate of 0.2 mm or smaller thickness is provided in a vertical direction to the surface plate in the strut, it has no component in a direction parallel to the surface plate except for the thickness, to have a shape without providing on a straight line at least three points of a surface plate support position formed at almost equal distances, the strut having a plurality of the surface plate support positions is constituted integrally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat discharge tube useful for a backlight or the like of a liquid crystal display device.

[0002]

2. Description of the Related Art Flat-type lamps are used in various industrial fields by taking advantage of the space-saving feature of not being bulky. In particular, for a liquid crystal display device which is a non-emission type flat display, a thin and lightweight lamp with high efficiency is desired.

As a backlight lamp, a high-efficiency discharge tube has been awarded. However, since the manufacture using a glass tube is easy, the lamp shape is a cylinder or a modified one thereof. Various light guide systems for applying this to a liquid crystal display device have been developed, but the following problems are pointed out. (1) Since the number of components such as the light guide plate, the reflection plate, and the diffusion plate is large, the cost of components and assembly is large. (2) There is a loss in the component itself or the component connection part, resulting in poor light use efficiency. (3) It is difficult to obtain uniform surface luminance. Under such circumstances, it has been proposed to make the lamp itself flat. When a flat discharge tube (hereinafter simply abbreviated as a discharge tube when not confused) becomes large, it is necessary to form a column inside the airtight container. For example, if the support is not used with a 10-inch diagonal face plate, the required glass plate thickness is 10 mm.
This is because the feature of thinness and light weight is lost because it reaches about mm.

[0004] Since the discharge occurs along the space connecting the electrodes, the discharge direction of a general discharge tube in which the electrodes are formed parallel to the face plate is parallel to the face plate.

[0005] In order not to reduce the efficiency of the discharge, the pillars formed in the discharge space are installed so as not to obstruct the discharge direction as much as possible. For example, in the case of a plate-shaped support which is easy to form and has a high support effect, the support plate surface is made parallel to the discharge direction. However, since the support must also be perpendicular to the face plate, the direction in which the plate-like support can be formed is limited in a discharge tube in a discharge direction parallel to the face plate. Therefore, easy formation, assembling, and optimal arrangement of the columns can be restricted.

In view of the above, there has been proposed a discharge tube whose discharge direction is perpendicular to the face plate. FIG. 3 is an exploded perspective view of the main part.

[0007] A front plate 1 and a back plate 2 each having a rectangular shape having substantially the same area.
Are opposed to each other with the side plate 3 interposed therebetween, and a joint portion of each member is fixed and sealed with low-melting-point sealing glass to form an airtight container. In addition, a column 4 having the same height as the side plate is formed inside the airtight container so that a pressure difference between the inside and outside of the container can be supported by a thin plate. In addition, assembling becomes easier when the support is fixed to one of the face plates using a seal glass or the like.

The one electrode 5 is formed in a film shape on the outside of the front glass plate with a transparent material (for example, ITO). The other electrode 5 ′ is formed in a film on the inside of the back plate, and its surface is covered with a dielectric 6. In the case of a backlight, the back electrode 5 'need not be transparent. For connection of these electrodes to an external circuit, it is preferable to provide a portion where the membrane electrode extends outside the side plate and is not covered with a dielectric.

A phosphor (omitted from the figure) is attached to the inner surface of the airtight container and the surface of the column, and emits visible light with ultraviolet rays generated by electric discharge. When used as a backlight, it is preferable that the front side is easy to transmit light and the rear side is reflective. In general, low-priced plate glass is awarded for both double-sided plates, and the application of the phosphor as a white powder is made thicker on the rear plate and thinner on the front plate. It is also often used to form a light reflection layer inside or outside the back plate.

Although not shown, an exhaust pipe is attached to the side plate or the rear plate, and after exhaust and discharge gas introduction, the tip is turned off to complete the discharge tube.

Although the above is a typical configuration example, depending on the material, each member can be divided or formed integrally. The members to be fixed are resistant to the heat process, and those having similar thermal expansion coefficients are selected. This is to prevent deformation of each member and breakage of brittle materials such as glass. Further, a necessary portion at the member joining portion is hermetically sealed with a seal glass or the like.

The distance between the face plates needs to be 1 mm or more. This is to ensure the efficiency of discharge and the life of the electrode (discharge surface). These properties are affected by the product of the discharge gas pressure and the distance between the electrodes, but require a relatively large value. Face plate spacing 1
If it is less than mm, sufficient characteristics cannot be ensured even if the gas pressure is increased up to 1 atm. Although there is no upper limit on the characteristics, the distance between the face plates is preferably 10 mm or less in order to make the discharge tube compact or to facilitate the formation and assembly of the side plates and the columns.

A problem with the pressure difference between the inside and outside of the discharge tube (including the manufacturing process) is a face plate having a large area. The required face plate thickness is determined by the maximum value of the interval between the supports (side plates and support columns) that support the face plate in the vertical direction. Therefore, in order to efficiently support the face plate with as few struts as possible, the plurality of face plate support positions should be at the same distance. For example,
The intersection of the shape obtained by dividing the face plate into a lattice, a triangle, a honeycomb, or the like is a suitable position for forming a support. In FIG. 3, pillar-shaped pillars are formed at four locations in a grid where the face plate is divided into nine equal parts.

The problems of the above-mentioned column of the discharge tube are as follows. In order to stably stand the plate-shaped or column-shaped column in the direction perpendicular to the face plate, it is better that the column has a large root thickness. For example, it is 1/2 or more of the height. However, since these block the discharge direction, the larger the size, the larger the non-light-emitting area, which is not preferable. This is because if the non-light-emitting portion is conspicuous, extra measures such as attaching a light diffusion plate are required. Of course, when the size is reduced, the mounting becomes unstable due to the instability.

The larger the number of divisions of the face plate, the more preferable it is that a thin face plate can be used. In such a case, it is convenient to form a plate-like column by connecting the linearly formed portions. Since the conventional plate-shaped support has a strip shape that can be easily formed, a portion in contact with the face plate is linear. Therefore, there is a problem that a non-light emitting portion is formed to be long even with a pillar having a small thickness.

As described above, in the conventional discharge tube, it is impossible to simultaneously satisfy the requirements such as easy formation and attachment of the columns and non-conspicuous non-light emitting portions generated in the columns. It is the current situation.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to provide a discharge tube which can be easily formed even with an inconspicuous column.

[0018]

The inventor of the present invention has made intensive studies and found that the above-mentioned object can be attained by providing a support for supporting the face plate with a metal plate having a thickness of 0.2 mm or less standing upright on the face plate. This led to the present invention.

That is, the present invention includes the following (1) and (2). (1) An airtight container containing a discharge gas is composed of two facing rectangular face plates, a side plate supporting an outer peripheral portion of the face plate, and a column supporting the face plate inside the container, and the discharge direction is perpendicular to the face plate. A flat-type discharge tube, in which a metal plate having a thickness of 0.2 mm or less is set upright in the direction perpendicular to the face plate, and has no component other than the thickness in a direction parallel to the face plate, and is formed at substantially the same distance as the face plate support position. Wherein at least three points are not on a straight line and a support having a plurality of face plate support positions is integrally formed.

(2) The height of the support metal plate other than the support positions of the face plates formed at substantially equal distances is smaller than the spacing between the face plates, and the support surface exposed to the discharge space is covered with a phosphor. The flat discharge tube according to claim 1, characterized in that:

Hereinafter, the characteristic portions of the present invention will be described in detail. The discharge direction of the flat discharge tube of the present invention is perpendicular to the face plate and coincides with the support direction of the column. For this reason, in the case of a column in which a thin metal plate is set upright on the face plate, the portion that hinders discharge is only the thickness and can be made inconspicuous as a lamp. Further, since the supporting direction is the same as that of the discharge, and there is no restriction on the position of the column, the minimum number of columns may be formed at the most efficient portion. Further, the support component of the present invention is only a metal plate perpendicular to the face plate, but has a planar configuration along the face plate. Therefore, the stability is improved, the assembling is easy, and the practical supporting strength is high.

The thinner the metal plate, the better the support strength is allowed. The required thickness varies depending on the distance between the columns and the inclination of the columns. Since the support of the present invention has high stability due to the shape of the support, the properties of the material can be fully utilized. As the metal material, a material close to the thermal expansion of the face glass is selected. Ni. Cr. An alloy selected from the Co element is exemplified. From these mechanical properties, the thickness of the support metal plate is 0.2 mm or less and has sufficiently practical strength. Above this point, the material is wasted, and the non-light-emitting portions formed by the pillars stand out.

The distance between the columns is determined by the strength of the face plate used. For example, the distance between columns that can be tolerated with a glass face plate having a thickness of about 2 mm is 30 mm or less. In such a range, the thickness of the metal plate is 0.1. It may be 1 mm or less. The distance between the columns is selected in consideration of the time required for forming the columns and the thickness of the discharge tube.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention in which a column is formed in a plane along a face plate will be described with reference to FIG. FIG. 1 is a perspective view of a single metal plate bent four times to form a quadrangular cylindrical support. The end faces of the metal plate that has gone around may be separated or joined. Of course, the shape is L-shaped, U-shaped,
Various things such as cylinders are possible. The essential point is that it is only necessary to be constituted by a curve having directional components that intersect in a plan view. Figure 4 shows the four corners of the strut
Of the four pillars. Since each corner is supported by orthogonal sides, the overall stability is much higher. In addition, since the side plate connecting the corner supports the face plate, it can withstand a greater force.

As can be seen from FIG. 1, even if efficient support positions are scattered in a plane, an integral support can be formed by an easy method such as bending a single metal plate. Therefore, even if the number of supporting positions increases, the time required for forming the support columns does not increase so much, so that a thinner face plate can be used. Generally, a single metal plate is preferred since it has the least number of components, but depending on the shape, it may be composed of a plurality of metal plates. For example, a lattice-shaped column formed by combining metal plates vertically and horizontally does not require much labor to form, and enables high stability and efficient face plate support.

Another embodiment of the present invention will be described with reference to FIG. There is also a problem with the strut having the configuration as shown in FIG. That is, a line-shaped non-light-emitting portion is formed along the column.

When the phosphor is also applied to the surface of the support, the influence of the support being a non-light emitting portion and blocking light can be reduced. However, if the face plate is also supported at the side portions as shown in FIG. 2, even if the phosphor can be applied, it cannot emit light, so that a non-light emitting line is formed. It is easy to notice even if the line is thin with a thin metal plate.

FIG. 2 shows an example of a support which improves this point. FIG. 2 is the same as FIG. 1 except that the width of the side portion is reduced to provide a gap between the face plate. As described above, since the effective support position in the figure is near the meeting point of the grid, sufficient pressure resistance can be obtained without supporting at the sides. If the phosphor is also applied to the end face of the metal plate having a reduced width, it is exposed to the discharge space and irradiated with ultraviolet rays, so that this face also emits light. Therefore, the non-light emitting area can be limited to a small portion of the intersection. The support using a metal plate also facilitates the application of the phosphor. Since the application surface can be made flat, a simple method such as a printing method can be applied even to a plurality of components at once. Bending and assembly are performed after printing. The end face of the metal plate is also thin, so that it can be easily applied by dripping of the ink.

The metal support inserted between the pair of electrodes covered with the dielectric functions as an auxiliary electrode. This is because the electrode capacity in this portion is increased, and thus a discharge starting point is formed. If the electrode is formed of an exposed conductor, it can be used similarly if its surface is covered with a dielectric so that the support metal does not short-circuit the electrode. The capacitance can be easily adjusted by adjusting the dielectric constant, area and thickness of the covering dielectric.

The effect of covering the pillar with the dielectric is not limited to the case of the exposed electrode. For example, some metals can easily absorb and release gas, which may have an adverse effect such as a decrease in discharge gas and an increase in impurity gas. If such a metal is coated with a dense dielectric such as glass, the problem will be eliminated. Further, there is a case where it is desired to reduce the electrode capacity in order to reduce the driving power. For this purpose, it is preferable to thickly cover a portion where the metal plate is in contact with the face plate with a dielectric having a small dielectric constant.

A discharge tube is constructed by using the above-mentioned columns in the same manner as in FIG. A rare gas or Hg is generally used as a discharge gas. A method for driving the discharge tube may be the same as the conventional one.

As will be understood from the above description, it is needless to say that the discharge tube of the present invention is not limited to the configurations shown in FIGS. For example, the method of dividing the face plate for determining the column support portion is arbitrary, and many shapes can be applied. In addition, since the efficient support position may be any position close to the division intersection, it may not be a geometrically strict position. Further, it will be understood that the prior art can be used in portions other than the description, since not much change is required in portions other than the strut configuration.

[0033]

The discharge tube of the present invention has the following effects. (1) Since a thin metal plate can be stably stood upright in the vertical direction of the face plate, an obstructing pillar area can be reduced. (2) Even if it is a support corresponding to a plurality of face plate support locations,
Since it can be integrated, the labor of formation is small. (3) Since a large number of supporting portions can be easily formed, a thin discharge plate can be used and a compact discharge tube can be obtained. (4) Since the phosphor can be applied to the surface of the pillar other than the efficient supporting portion to emit light, the non-light emitting area can be further reduced. (5) Since it does not include any new materials or processes, the prior art can be used and manufacturing is easy.

[Brief description of the drawings]

FIG. 1 is a perspective view of a column used in an embodiment of the present invention.

FIG. 2 is a perspective view of a column used in another embodiment of the present invention.

FIG. 3 is an exploded perspective view of a main part of a conventional discharge tube.

[Explanation of symbols]

1: front plate, 2: back plate, 3: side plate, 4: support, 5,
5 ': discharge electrode, 6: coated dielectric.

Claims (2)

[Claims] An airtight container accommodating a discharge gas is composed of two facing rectangular face plates, a side plate supporting an outer peripheral portion of the face plate, and a column supporting the face plate inside the container, and a discharge direction is perpendicular to the face plate. A flat discharge tube having a thickness of 0.2 mm
A column that has the following metal plate vertically set on the face plate has no component in the direction parallel to the face plate except for the thickness, and at least three points of the face plate supporting position formed at substantially the same distance are not on a straight line, A flat discharge tube, wherein a support having a plurality of face plate support positions is integrally formed. 2. The height of the support metal plate other than the face plate support position formed at substantially the same distance is smaller than the face plate interval,
The flat-type discharge tube according to claim 1, wherein the support surface exposed to the discharge space is coated with a phosphor.