JP3187589B2 - Flat type light source and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin flat light source used for a backlight of a liquid crystal display, indoor lighting and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a structural diagram of a conventional flat light source disclosed in Japanese Patent Publication No.
In the drawing, reference numeral 120 denotes a front glass substrate formed into a bottomed frame shape, 121 denotes a rear glass substrate having a flat plate shape, and 122 denotes a phosphor that emits light by radiating ultraviolet rays.
Is a phosphor film formed by being adhered to the inner surface of the substrate. 12
Reference numeral 3 denotes a conductor electrode film disposed in parallel on the inner surface of the rear glass substrate 121, and the conductor electrode film 123 is formed by patterning by screen printing or vapor deposition. 124 is a dielectric film formed by screen printing or vapor deposition, 125 is an MgO film for lowering the discharge voltage and protecting the dielectric film 124 from discharge, and 126 is a discharge space filled with a discharge gas such as Hg.

A conventional flat light source is constructed as described above, and alternately applies an alternating potential of 20 to 50 kHz having an amplitude exceeding a discharge voltage to each line of the conductor electrode film 123, thereby forming a dielectric film 124 and an MgO film. An AC discharge is generated in the discharge space 126 via the film 125. On this occasion,
Since the MgO film 125 has a high secondary electron emission ability, the MgO film 125 has an effect of lowering a discharge voltage and slowing down electrode consumption due to sputtering. The discharge gas excited by the discharge emits ultraviolet rays, and the front glass substrate 120
The phosphor film 122 attached to the inner surface of the substrate emits light.
Since this light source can generate discharge uniformly on the inner surface of the rear glass substrate 121, it can be used as a flat surface emitting light source.

Further, an envelope for defining a discharge space of this type of light source is formed in a hollow flat plate type, and most of them are made of sheet glass. In addition, the thickness of the substrate cannot be extremely increased from the viewpoint of reducing the weight and space of the product. For this reason, for example, when trying to manufacture a large-sized flat surface emitting light source having a diagonal size of 5 inches or more, the envelope is distorted due to stress caused by a pressure difference between the inside and the outside of the envelope, Eventually, the envelope itself may be destroyed. As a solution to this problem, see, for example,
Japanese Patent Application Laid-Open No. 225743 discloses a structure in which a spherical glass spacer 130 is disposed in a discharge space 126 to support the flat substrates 131 and 132 as shown in FIG. In the figure, 133 indicates planar substrates 131 and 132
It is an outer frame part for sealing the space between and making it an envelope,
The outer frame part 133 is formed of low melting point glass. Also, 1
34 and 135 are electrodes provided on the outer surfaces of the planar substrates 131 and 132, respectively. That is, the glass spacer 13
0 serves as a support between the planar substrates 131 and 132, and prevents the envelope from being broken by a pressure difference between the pressure inside the envelope and the atmospheric pressure.

[0005]

First, the conventional flat light source shown in FIG. 11 is considered to have a basic electrode structure which is substantially the same as that of a so-called transmission type color AC type plasma display. However, since the phosphor film is formed only on the inner surface of the front glass substrate 120, the ultraviolet rays emitted in the direction of the rear glass substrate 121 are not used for light emission at all, There is a problem that luminous efficiency is extremely low.

The size of the flat light source can be increased by the method shown in FIG. 12. However, since the glass spacer 130 is present in the discharge space 126, it blocks ultraviolet rays, and In the vicinity of the above, there is a problem that the ultraviolet light does not reach the phosphor film and a dark portion is formed in the light emitting surface.

In the case of a relatively small envelope having a rectangular side of 50 mm or less in length, for example, 2 m
Even if a glass plate having a thickness of about m is used for the substrate, it can sufficiently withstand the pressure difference. Therefore, it is not necessary to arrange the glass spacer 130 in the discharge space as shown in FIG. Is small, no glass spacer is required in the discharge space 126. In such a case, an envelope formed into a bottomed frame such as a front glass substrate 120 shown in FIG. 11 or a frame using a frame-shaped bar as a spacer between two flat substrates is used. However, all of them require time and effort to process, which has been a factor of cost increase.

The present invention has been made to solve such a problem, and a flat light source capable of performing surface emission with high luminous efficiency while using a method of exciting and emitting a phosphor by ultraviolet rays generated by discharge. The purpose is to get. It is also desirable to obtain a flat-type light source having a large-sized (for example, a rectangular surface light source having a length and width exceeding 100 mm each) which does not generate a dark portion in a light emitting surface. The purpose is. Still another object of the present invention is to provide a method for easily manufacturing an envelope when it is not necessary to arrange a glass spacer in a discharge space.

[0009]

[0010]

Means for Solving the Problems] plate type light source according to the invention of claim 1 has a front Menmoto plate, disposed opposite to the front substrate
Between the back substrate and the front substrate.
An outer frame that forms a closed discharge space;
A first phosphor film provided in the discharge space of
A dielectric film provided in the discharge space on the surface substrate;
A pair of electrode films provided on the dielectric film;
And an insulator plate provided on the dielectric film, and the insulator
A second phosphor film provided in the discharge space on the plate .

[0011] The flat type light source according to the invention of claim 2 is characterized in that
A wide part and a width in which the distance between the electrodes changes in a pair of electrode films
It has a narrow portion .

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

In the flat light source configured as described above,
, The insulator plate functions as a dielectric covering the conductor film, and suppresses discharge current.

Further, a pattern electrode formed by patterning a plurality of strip-shaped conductor electrode films in which a wide portion and a narrow portion are alternately arranged at regular intervals defines a discharge location and suppresses a discharge current.

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

【Example】

Embodiment 1 FIG. FIG. 1 is a sectional view showing an embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 1 is a transparent front substrate, 2
Denotes a rear substrate, and the front substrate 1 and the rear substrate 2 are usually made of glass. Reference numeral 3 denotes a frame portion disposed between the front substrate 1 and the rear substrate 2 and at the peripheral edge of both substrates, and for sealing a space between the two substrates to form a complete envelope. The frame 3 and both substrates are hermetically sealed by melting low-melting glass or the like.

Reference numeral 4 denotes a phosphor film formed of a phosphor that emits ultraviolet light in the vacuum ultraviolet region.
Is attached to the inside surface. Reference numeral 5 denotes a phosphor film 5 formed of the same phosphor as the phosphor film 4, and a dielectric film 124.
Is attached to the surface. The gap between the patterns of the conductor electrode film 123 is, for example, 0.5 mm or less, and the conductor electrode film 123 has a lead portion (not shown) to the outside of the envelope. For example, several tens to several hundred Torr of Xe gas is sealed in the discharge space 126.

Next, the operation of this embodiment will be described.
When a voltage higher than the discharge voltage is alternately applied between adjacent electrodes of the patterned conductor electrode film 123, an AC discharge occurs between them. Since the dielectric film 124 is formed on the conductor electrode film 123, this discharge is completed within approximately 1 μsec depending on the conditions, for example, in the case of an electric field that quickly rises in a pulse shape, and ends until the next pulse is applied. Discharge is not sustained. When, for example, a gas of Xe is used by this discharge, an excimer Xe ₂ is generated, and ultraviolet rays in a vacuum ultraviolet region are emitted during transition to the ground state. The ultraviolet light emitted from the excimer does not attenuate normally because it does not undergo a self-absorption phenomenon that is absorbed by the discharge gas molecules itself, and can reach the phosphor films 4 and 5 on the front substrate 1 and the rear substrate 2 without being attenuated. I can do it. The phosphor films 4 and 5 are excited and emitted by ultraviolet light, and the emitted light is extracted as visible light through the front substrate 1.

At this time, since the phosphor films 4 and 5 are usually white, the light emitted from the phosphor film 4 on the inner surface of the front substrate 1 passes through the front substrate 1 and the phosphor film 5 on the rear substrate 2
, And returns to the front substrate 1 again, so that the brightness increases synergistically. Thereby, there is an effect that uniform fine luminance unevenness caused by the pattern shape of the conductor electrode film 123 is uniformed. In addition, the electrode surface of this example is a bare phosphor, and no electrode protection material such as MgO is used. However, as a result of the experiment, in the case of excimer discharge, deterioration of the phosphor film due to sputtering was almost observed. There is no practical problem.

Embodiment 2 FIG. FIG. 2 shows another embodiment of the flat type light source using the same principle as that of the first embodiment. In the drawing, the same parts as those of FIG. I do. In this embodiment, an electrode or the like is not formed on the inner surface of the back substrate 2, but an electrode 8 or the like is separately formed using a thin insulator plate 7 made of glass or ceramic as a substrate, and this is formed on the back surface. It is installed on the inner surface of the substrate 2.

For the electrodes 8 and the like, the phosphor film 5 is applied to one surface of the insulator plate 7, and the conductor electrode film 123 is formed on the other surface in the same manner as in the first embodiment. On the upper surface, a dielectric film 124 is formed. As shown in FIG. 2, the electrodes 8 and the like are provided with the dielectric film 124 adhered to the inner surface of the rear substrate 2 and the phosphor film 5 facing the discharge space 126. The insulator plate 7 and the conductor electrode 5 are in close contact,
Functionally, the insulator plate 7 is the dielectric film 12 in the first embodiment.
In this embodiment, the dielectric film 124 merely functions as a coating for preventing dielectric breakdown.

The operation is exactly the same as that shown in the first embodiment, but by using a thin glass or ceramic plate as a dielectric instead of the dielectric film 124, high uniformity which is difficult to obtain with a screen print film is obtained. Can be obtained. Also, since a relatively small dielectric constant can be obtained, it is possible to easily control an excessive discharge current,
High luminous efficiency can be obtained.

Embodiment 3 FIG. FIG. 3 is a plan view of a pattern of a conductive electrode film according to one embodiment of the present invention. In the figure, reference numeral 9 denotes a patterned conductive electrode film. The conductive electrode film 9 has a shape in which wide portions 9a and narrow portions 9b are alternately continuous, and a plurality of strip-shaped conductive electrode films 9 are provided side by side. Are formed. That is, the pattern shape of the conductor electrode film 9 is not a simple linear parallel pattern, but is configured so that the inter-electrode distance between adjacent conductor electrodes changes regularly. In the discharge electrode film 9 configured as described above, by controlling the discharge voltage, a streamer can be generated only in a portion where the distance between the electrodes is minimum. That is, the discharge voltage may be set to such a value that discharge occurs when the distance between the electrodes is minimum, and does not occur when the distance between the electrodes is longer than that. Thereby, the discharge current flowing through the entire light source can be suppressed, and as a result, the luminous efficiency can be increased. Further, it becomes possible to control the discharge current value by the applied voltage.

Embodiment 4 FIG. FIG. 4 is a cross-sectional view of a flat light source showing one embodiment of the present invention. In FIG. 4, the same parts as those in FIG. In this embodiment, the spherical glass spacer 3 shown in the conventional example is used.
A glass spacer 11 having a cone shape is provided instead of 0, and the glass spacer 11 is arranged such that the bottom surface contacts the inner surface of the rear substrate 2 and the vertex contacts the inner surface of the front substrate 1. The shape of the glass spacer 11 may be basically a cone or a quadrangular pyramid as long as it is a cone, but a particularly preferred shape is a regular tetrahedron having the same height regardless of which surface is the bottom surface. This is because, in the case of a regular tetrahedron, the direction of the installation surface of the glass spacer can be arbitrarily determined when a flat light source is manufactured. Since the glass spacer is formed in a cone shape and its vertex is in contact with the front substrate 1, ultraviolet light can reach the vertex of the glass spacer of the phosphor film 122 on the front substrate 1 from the surroundings. Regardless, the entire surface of the phosphor film 22 can emit light.

Embodiment 5 FIG. FIG. 5 shows LiF, MgF ₂ , and Ca in place of the glass spacer 30 shown in the conventional example.
A spherical spacer 12 made of any one of F ₂ and BaF ₂ is provided. The shape of the spacer is not limited to a spherical shape, and may be, for example, a cone, a column, or the like. Since all of these materials have a property of transmitting ultraviolet light in the vacuum ultraviolet region, ultraviolet light from the surroundings also reaches the phosphor film near the spacer, so that the entire surface of the phosphor film 22 is irrespective of the presence of the spacer. To emit light.

Embodiment 6 FIG. FIG. 6 is a sectional view of one embodiment of the present invention, in which 13 is a front substrate. As shown in the figure, the front substrate 13 is a conventional flat plate which has a periodic undulation and has a wavy cross section. Reference numeral 13a denotes a vertex of the inner surface of the front substrate 13 and a portion in contact with the rear substrate 2. Since this portion acts as a support, even if the entire envelope becomes large, if the swell period is constant, the atmospheric pressure is maintained. Can withstand the stress caused by the pressure difference.

Embodiment 7 FIG. FIG. 7 is a cross-sectional view of another embodiment. In the drawing, reference numeral 14 denotes a front substrate, and 14a denotes projections having a constant height regularly provided on the inner surface of the front substrate 14. Since the projections 14a act as columns between the front substrate 14 and the rear substrate 2, the front substrate 14 can withstand the stress caused by the differential pressure even when the entire envelope becomes large. In addition, by applying a phosphor to the surface of each projection, it is possible to avoid the occurrence of a dark portion due to the influence of the presence of the projection.

Embodiment 8 FIG. In the flat light source, Ar, Kr, or Xe, or a mixed gas thereof, is sealed in an envelope as a discharge gas for generating an excimer, and He or Ne is mixed with these discharge gases to form the entire sealed gas. Is set to approximately one atmosphere. Since He or Ne does not contribute to the discharge, it hardly affects the discharge characteristics. This eliminates the pressure difference between the pressure of the sealed gas and the atmospheric pressure, so that no stress occurs in the envelope.

Embodiment 9 FIG. FIG. 8 is a main configuration diagram showing a main configuration of a manufacturing apparatus for manufacturing a flat light source in which the pressure of a sealed gas as shown in Embodiment 8 is approximately 1 atm. In the figure, 15 is a vacuum chamber, 16 is a heating device such as an infrared lamp installed in the vacuum chamber 15, and 17 is a flat light source in the vacuum chamber 15 filled with a discharge gas. One end 18 is connected to the exhaust port of the envelope of the flat light source 17, the other end is branched into two branches, and a vacuum pump (not shown) is connected to one of the branch pipes 18a.
An exhaust pipe 8b is connected to a discharge gas introduction system (not shown). Reference numeral 19a denotes an exhaust pipe for exhausting the vacuum chamber 15, one end of which is connected to a vacuum pump (not shown). 19b is a vacuum chamber 15
It is a pressure adjusting gas introduction pipe for introducing a gas for adjusting the internal pressure. Reference numerals 20, 21, 22, and 23 denote vacuum valves provided in the middle of the branch pipe 18a, the branch pipe 18b, the exhaust pipe 19a, and the pressure adjusting gas introduction pipe 19b, respectively.

Next, a method of manufacturing a flat panel using the manufacturing apparatus configured as described above will be described. First, the envelope in which the conductor electrode film, the dielectric film, the phosphor film, the sealing peripheral portion, and the exhaust port are all mounted is placed in the vacuum chamber 15.
And one end of the exhaust pipe 18 is connected to the exhaust port of the envelope, and one ends of the branch pipes 18a and 18b are connected to a vacuum pump and a gas introduction system, respectively. Next, the vacuum pump is operated to evacuate so that the pressure inside the envelope 17 and the pressure inside the vacuum chamber 15 become substantially the same. At this time, the entire envelope 17 is heated by the heating device 16 to exhaust the internal adsorbed gas. When the internal pressure of the envelope 17 reaches a predetermined degree of vacuum, the evacuation is terminated, the discharge gas is supplied from the branch pipe 18b, and the pressure control gas is supplied from the pressure control gas introduction pipe 19b (the discharge gas is expensive and other inexpensive gas is used). The gas is introduced while the pressure in the envelope 17 and the pressure in the vacuum chamber 15 are substantially the same. When the gas introduction is completed, the chip is turned off by the exhaust pipe 18 and then the envelope 17 is moved to the vacuum chamber 1.
Remove from 5.

According to the above method, no pressure difference occurs between the inside and the outside of the envelope during the process of exhausting and introducing the gas, so that the envelope can withstand the stress caused by the pressure difference of 1 atm. A flat light source can be manufactured even if it does not have sufficient strength.

Embodiment 10 FIG. FIG. 9 is a sectional view of the flat light source of the present invention. In the figure, reference numeral 25 denotes an outer frame portion made of low-melting glass which holds the front substrate 1 and the rear substrate 2 at a fixed distance and forms the side surface of the envelope. Reference numerals 25a and 25b denote small holes provided in the outer frame portion 25. For example, when the outer frame portion 25 is rectangular, one small hole is provided on each of at least three sides. For example, when screen printing is used to form the small holes 25a and 25b in the outer frame portion 25, it can be easily implemented by using a mask having a pattern as shown in FIG. Reference numerals 27 and 28 denote glass or ceramic cone-shaped small piece members put in the small holes 25a and 25b, respectively. The small piece members 27 and 28 are the front substrate 1 and the rear substrate 2 respectively.
And the bottom surface and the apex thereof are in contact with the front substrate 1 and the rear substrate 2, respectively.

Next, a method of manufacturing the above-mentioned flat light source will be described. First, the thickness of the outer frame portion 25 is formed to be slightly thicker than the height of the small piece members 27 and 28. Small hole 2 of outer frame 25
The small piece members 27, 28,... Are arranged in 5a, 25b,.
Then, the front substrate 1 is placed on the upper surface of the outer frame 25, and both substrates are pressed against the outer frame 25 using a spring material or the like. The outer frame 25 is melted by heating to seal. At this time, when the outer frame portion 25 is melted by heating, the distance between the two substrates is gradually narrowed, and sealing is performed at the position where the height of the small piece member is reached.

The material of the small piece members 27 and 28 is not limited to glass or ceramic, but may be any other material as long as the material does not soften at the melting temperature of the low-melting glass used for the outer frame 25. Also, the small piece members 27 and 28
Is not limited to a conical shape, and may be, for example, a columnar shape or a spherical shape as long as the distance between the two substrates can be maintained at a fixed distance when the envelope is sealed. After the sealing, the stress does not concentrate on the small piece member. Therefore, if appropriate conditions are used, the envelope is not damaged by heat treatment or the like in the exhaust process.

[0047]

Since the present invention is configured as described above, it has the following effects.

[0048]

Since the insulator plate functions as a dielectric covering the conductive film, high uniformity, which is difficult to obtain with a screen-printed film, and a relatively small dielectric constant can be obtained. Light emission and high luminous efficiency can be realized.

Further, since the conductor electrode film is formed in a pattern such that a plurality of strip-shaped conductor electrode films in which wide portions and narrow portions are alternately arranged are arranged at regular intervals, the pattern electrodes define discharge locations. As a result, the discharge current can be suppressed, and the luminous efficiency can be increased.

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a plan view of a third embodiment of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a seventh embodiment of the present invention.

FIG. 8 is a main configuration diagram showing a main configuration of an apparatus for performing the method shown in the ninth embodiment of the present invention.

FIG. 9 is a sectional view of a tenth embodiment of the present invention.

FIG. 10 is a plan view of a mask used for implementing a tenth embodiment of the present invention.

FIG. 11 is a cross-sectional view of a conventional flat light source.

FIG. 12 is a cross-sectional view of a conventional flat light source.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 front flat substrate 2 back substrate 3 outer frame 4 phosphor film 5 phosphor film 7 insulator plate 8 electrode 9 conductor electrode film 9 a wide portion 9 b narrow portion 11 cone-shaped small piece member 12 LiF, MgF ₂ , CaF ₂ , small piece member made of any material of BaF ₂ 13 front substrate 13a vertex of inner surface of front substrate 14 front substrate 14a projection of front substrate 15 vacuum chamber 16 heating device 17 flat light source 25 outer frame portion 25a, 25b small hole 27, 28 Conical small piece member 123 Conductor electrode film 124 Dielectric film 126 Discharge space

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Goro Kobayashi 2--14-40, Ofuna, Kamakura-shi Mitsubishi Electric Corporation Lifestyle Systems Research Laboratory (72) Inventor Takeo Nisachi 2--14-40, Ofuna, Kamakura-shi Mitsubishi Electric Corporation Lifestyle Research Institute (72) Inventor Masao Kano 2-14-40 Ofuna, Kamakura City Mitsubishi Electric Corporation Lifestyle Research Institute (56) References JP-A-2-112145 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01J 65/00

Claims (2)

(57) [Claims] And 1. A front Menmoto plate, disposed opposite of this front substrate
Between the back substrate and the front substrate
An outer frame for forming a sealed discharge space, and the front substrate
A first phosphor film provided in the discharge space above,
A dielectric film provided in the discharge space on the rear substrate;
A pair of electrode films provided on a dielectric film of
And an insulator plate provided on the dielectric film,
A flat light source comprising: a second phosphor film provided in the discharge space on a body plate . 2. The pair of electrode films, wherein the distance between the electrodes is
Contractors characterized by having varying wide and narrow sections
The flat light source according to claim 1 .