JP2673638B2 - Discharge display device using light guide plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various display devices using a light guide plate.

[0002]

2. Description of the Related Art There are various types of display devices that use glass for the display surface. For example, cathode ray tube (CRT), discharge display tube (PDP), liquid crystal (LCD), fluorescent display tube (VF)
D), electroluminescence (ELD), and other display devices.

The role of this glass is to (1) transmit display light emission, (2) protect display device components, (3) form part of an airtight container, and (4) control the pressure difference between the inside and outside of the container. Withstand, (5) serve as a substrate for circuit formation, etc.

Therefore, the glass thickness varies depending on the size of the display device, but is usually about 1 to 10 mm.

On the other hand, a color filter is used to improve the display quality. When a color filter corresponding to each emission color is used, the emission brightness is less reduced, the reflectance is reduced, and the contrast is improved. Also, the color purity can be improved. This is because the phosphor used for light emission generally has a high reflectance and a plurality of emission wavelengths. Further, in a color liquid crystal display device, a color filter is almost essential.

At this time, the arrangement position of the color filter becomes a problem. When the color filter is formed on the outer surface of the front glass of the display device, the viewing angle is reduced. This is because the light from a large number of cells travels through the glass at a wide angle, and reaches and mixes with colors other than the corresponding color filters. In order to avoid this color mixture, it is necessary to arrange each color filter at intervals larger than the glass thickness. As described above, if the thickness of the glass plate is 1 mm or more, fine cells cannot be formed. Therefore, in a fine display device, the color filter is generally formed inside the front glass.

When the color filter is formed on the inner surface, its material is restricted. That is, it is necessary to be stable at the operating temperature in the device forming process and not to cause adverse effects by reacting with substances in the device.

Except for the liquid crystal display device, a high temperature process of 400 ° C. or higher is required, and therefore an inorganic material color filter is essential. There are not many inorganic color filter materials with good characteristics, which are the three primary colors used as color filters. Some colored glasses are quite good, but the color density is low, so they must be made thick. This is complicated and has large irregularities, which is disadvantageous for fine patterning.

Even in the liquid crystal display device, the higher the heat resistance of the color filter, the better. A transparent electrode is formed on the color filter, and an electrode having better characteristics can be obtained as the forming temperature becomes higher.

When the color filter is formed on the inner surface, it is convenient to form various circuits on it. Therefore, the flatter the filter surface is, the more advantageous it is. When the unevenness of the color filter is large, it is necessary to additionally form a transparent flattening film.

As described above, in the conventional display device in which the display surface is made of glass, the place where the color filter is formed is limited, and thus the filter material is also restricted.
This has resulted in a loss of filter performance and other properties due to the narrow selection of filter materials. Or,
The current situation is that the process is complicated and cannot be formed inexpensively.

From this point of view, it is conceivable to use a light guide plate on the display surface. However, a light guide plate sufficient to solve the above-mentioned difficulties has not been obtained, and has not been applied to various display devices. This is because a fine display device requires a large number of fine light guide paths, and it has been considered difficult to form these at low cost. Due to its advantageous application in display devices, it is particularly difficult to form with limited materials.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems of the prior art and to provide a display device having good characteristics and low cost, and a light guide plate applicable to this device.

[0014]

The above object of the present invention is achieved by the following discharge display device.

That is, the discharge display device of the present invention has a plurality of light guides in the thickness direction, and a perforated metal plate having a through hole corresponding to the light guides is provided at a position separating the different light guides. It is characterized in that a perforated metal plate of a light guide plate, which is an airtight body whose through holes are filled with transparent glass, is used as an electrode.

Hereinafter, the present invention will be described in more detail. The requirement required in the present invention is to collectively form a light guide plate having a plurality of light guide paths in the thickness direction. Since this light guide plate is used as a display surface of a display device, it is desired that the light guide plate has stable and high heat resistance during the device manufacturing process.

Transparent glass is used as the translucent material.
There are many types of glass, but transparent and highly heat-resistant ones are widely known.

A perforated metal plate is used as a material for separating the plurality of light guide paths. The metal material has good workability and is convenient for collectively forming a large number of fine through holes. For example, a metal plate may be etched by photolithography. Generally, a metal having high heat resistance can be selected.

The through hole of the perforated metal plate is hermetically filled with transparent glass. Although there are many filling methods, a method of immersing a perforated metal plate in molten glass and then pulling it out, a method of filling the holes with powdered glass and then melting the glass, and the like can be used. In these filling steps, a temperature of 450 to 1000 ° C. is generally a suitable range. Glass that melts at such temperatures,
Alternatively, metals that do not have deformation or unnecessary reaction with glass are known. It is also well known to approximate the respective thermal expansions so that the metal and glass do not deform and break during cooling.

Depending on the types of metal and molten glass, foaming occurs at the contact portion. Light is diffused where foaming occurs, which is not preferable as a light guide path. Even if the foamed portion is small, it is a problem in a fine display device having a small cell.
Foaming is a chemical reaction between metal and glass, and when a large amount of metal dissolves in glass, the glass itself may devitrify. In addition, if the glass and the metal do not wet well, the overall strength becomes small.

As a general method for avoiding such an unfavorable phenomenon, the surface of a perforated metal plate is coated with an oxide. In general, many oxides do not cause a foaming reaction with molten glass. The thickness of the coating oxide is sufficient to prevent the above reaction and is within a range in which the reduction in the display aperture ratio is small. This is because the formed oxide layer and the portion that has reacted with the glass are not transparent. A preferable thickness is usually about 2 to 50 μm. In order to reduce the amount dissolved in glass, the coated oxide preferably has high fire resistance, and many suitable oxides are known.

Many oxide coating methods are known as metal surface treatment techniques, and these can be used. For example, (1) thermal oxidation of metal, (2) anodic oxidation of metal,
(3) Oxide sputtering, (4) Oxide spraying, (5)
For example, application of powdered oxide.

Of these, the methods (3) and (4) are
Since it is difficult to uniformly coat the inner surface of a perforated metal plate,
Not preferred.

The method (2) is limited to a special case because the types of metals that can be applied are limited and the types of glass and the materials of the device forming members are also limited. In this example, Al, Ti and alloys thereof can be applied. Depending on the method of anodic oxidation, the surface of the perforated metal plate can be colored and the reflectance can be increased.

The method (1) has a limit in the thickness of the coated oxide film. If it is thick, it will peel off due to the difference in thermal expansion. If the film is thin, the glass cannot be melted at high temperature for a long time. This is because the oxide film is entirely dissolved in the glass and the metal and the molten glass come into direct contact with each other. Such a state is likely to occur in a through hole filling operation that requires a large amount of glass. So this method
It may be used when coating a small amount of glass.

There are various coating methods in the method (5),
Select a material that can be uniformly applied to a perforated metal plate having a complicated surface. An electrostatic coating method and an electrodeposition method are suitable examples. In these methods, since the adhesion force between the powder and the metal is weak, there is a possibility that the glass filling step may be hindered. The opacity is because the powder is dispersed in the transparent glass. In this case, glass or an oxide containing glass may be selected as the powder, and the glass may be melted and fixed.

The oxide coating layer thus formed is referred to as a first dielectric in the present invention. First as above
The role of the dielectric is to prevent undesired reaction between the transparent glass to be filled and the metal. However, if there is no need, first
The dielectric can be omitted.

The first dielectric also has another function. In general, the first dielectric and the second dielectric, transparent glass, have different refractive indices. Therefore, light reflection occurs at these interfaces. When the reflectance of the interface is high, the display light passing through the light guide path is effectively guided to the outside. To increase the reflectance, first
As the dielectric, transparent glass may be compounded with oxide powder having a higher refractive index than this glass, for example, TiO ₂ , ZrO ₂ , Al ₂ O ₃ and compounds of these elements. Usually 50
% Or higher, preferably 70% or higher. Although the first dielectric is a white layer in the above example, it may be colored in the same color as the display light. If there are multiple display colors, they need to be painted separately.

On the contrary, if the reflectance is reduced, the light guide plate has a light-shielding performance determined by the thickness and the width of the perforated metal plate. The reflectance can be set to 15% or less by using a black inorganic pigment. The same thing can be done by using transparent glass as the first dielectric. This is because the reflectance at the interface between the glass and the perforated metal plate is generally small. Having a light-shielding property has a function of preventing display in an unnecessary direction and preventing external light from entering.

The second dielectric, the filled glass, is transparent. The term “transparent” may be colorless and transparent, or may be colored similar to the display color. In a display device having a plurality of emission colors, the colored second dielectrics are separately filled in the through holes. Since the perforated metal plate has the through holes, the glass powder of each color can be selectively filled by so-called through hole printing which is screen printing. This method is simple and well known. The thickness of the filled glass can be made as thick as a perforated metal plate, so that even a colored glass having a low concentration can be used as a color filter, and therefore, a material having excellent chromaticity can be selected.

The filling position of the second dielectric will be described. FIG.
[Fig. 4] is a partial schematic plan view of a light guide plate LG. In each of the following drawings, the same reference numeral indicates the same item.

The surface of the perforated metal plate M1 in which the rectangular through holes are arranged in a square is covered with the first dielectric D1. The through hole is filled with transparent glass which is the second dielectric D2 to form a light guide path. 2 (a) to 2 (d) are cross-sectional views taken along line XX 'of FIG.

The thickness of the second dielectric, which is transparent glass, is
It may be larger than the perforated metal plate as shown in (a) and (b) of the figure, or may be smaller as shown in (c) and (d) of the figure.
Of course the same can be used.

The surface of the light guide plate may or may not have a planar shape like the upper and lower surfaces of FIG. 9A and the upper surface of FIG. When forming a circuit or color filter on the light guide plate, a planar shape is convenient.

When the second dielectric has a convex lens shape as shown in FIG. 3B, the display light is effectively absorbed by the side wall of the perforated metal plate and is effectively guided to the outside. That is, the influence of the reflectance of the side wall portion is small. Even if it has a concave lens shape as shown in FIG. 7D, the display light is effectively guided to the outside if the reflectance of the side wall of the perforated metal plate is large.

The upper and lower surfaces of the perforated metal plate may be covered with a dielectric material or transparent glass, or may be exposed. When the upper and lower surfaces are covered with transparent glass, the thickness is preferably about the width of the side wall of the perforated metal plate or less. This is a measure for preventing bleeding of adjacent colors when a color filter is formed on the surface of the light guide plate. For example, if the transparent glass thickness is the same as the width of the light guide section, there is no color blur up to a viewing angle of about 45 degrees. When the perforated metal plate is exposed, insulation is required between the perforated metal plate and the adjacent exposed electrodes.

As described above, various shapes can be applied to the second dielectric material, but the shape is appropriately designed depending on its characteristics, easiness of formation, and convenience for use in a display device. Is.

The light guide path of the light guide plate generally corresponds to the display cells of the display device in a ratio of 1: 1. But,
A plurality of light guide paths may correspond to one display cell, and vice versa. In order to prevent the display aperture ratio from decreasing, it is preferable that the width of the light guide path partition portion of the perforated metal plate be smaller than the non-display portion that partitions the display cell.

The light guide plate of the present invention can be used as a component of various display devices, particularly as a display surface component. This is because it has good heat resistance and airtightness. CRT, PDP, LCD, V
An example is a display device using glass on the display surface such as FD and ELD, and the light guide plate of the present invention can be used in place of this glass. Since this light guide plate is reinforced with a perforated metal plate, it also has the advantage that it can be made thinner than an ordinary glass plate.

The perforated metal plate constituting the light guide plate of the present invention is
It can be used as an electrode of a PDP. There are various types of PDPs, which are roughly classified into DC type and AC type. D
An exposed perforated metal plate can be used as the C-type electrode, and a perforated metal plate covered with a dielectric can be used as the AC-type electrode. The perforated metal plate is common to the plurality of light guide paths, and thus may be common to the plurality of display cells. There are many known electrode configurations in such a case. Examples thereof include a common auxiliary anode used in DC type, an AC type common discharge electrode, and a DC / AC mixed type so-called trigger electrode.

[0041]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Known materials and process technologies other than those described are applied.

Example 1 A PDP was adopted as a display device. The adopted configuration is D
It is a C / AC mixed type and has a so-called reflective structure in which the light emission of the phosphor is directly observed. FIG. 3 (a) shows this partial schematic plan view, and FIG. 3 (b) shows a cross-sectional view of this portion YY '.

The partition for dividing the display cell C is a perforated metal plate M.
The partition wall PW is formed of 2 and the entire surface of the partition wall is covered with a dielectric material. The general forming method of this partition plate and the use as a PDP are described in JP-A-3-15283.
No. 0, JP-A-3-205738, JP-A-4-
It is described in detail in Japanese Patent No. 129131, Japanese Patent Application No. 4-54158 and the like. Specifically, 42 wt% Ni-6 wt% C
A metal plate having a thickness of 0.15 mm is etched with an r-Fe alloy to form a perforated metal plate in which substantially square holes having a length of 0.32 mm are arranged in a square shape with a vertical and horizontal pitch of 0.4 mm. This material has approximately the same thermal expansion as the window soda lime glass used as the back plate BP. A glass powder mixed with TiO ₂ powder was uniformly adhered to the surface of the perforated metal plate by an electrodeposition method using the one whose surface was thermally oxidized as an electrode, and was baked at 650 ° C. A white dense dielectric D having a thickness of about 10 μm was coated. The surface reflectance of the partition plate thus completed was 70% or more. Furthermore, on this surface MgO
Was formed.

A linear anode A is applied to the back plate BP in a parallel direction, and the fluorescent substance P is covered with a part of the anode exposed.

The light guide plate LG is manufactured as follows. The same partition plate was prepared. The perforated metal plate M1 coated with the first dielectric D1 was immersed in a slurry of low-melting glass powder, the glass powder was uniformly applied to the partition plate holes and the surface, dried, and fired at 600 ° C. This glass is the first
It has a softening point lower than that of the glass used for the dielectric material.
This glass is transparent and no foaming or the like is observed, and forms the second dielectric D2. The shape is as shown in FIG.
The total thickness is about 0.25 mm, so the thickness of the transparent glass above and below the perforated metal plate is about 40 μm. An extremely thin protective layer of MgO is formed on one surface of the light guide plate, and a line cathode K is vertically applied to the protective layer. A color filter F is formed on the opposite surface. The color filter is formed of a filter film of each color and a black light-shielding layer on the boundary between them. The position of the light shielding layer is right above the perforated metal plate of the light guide plate. Since the color filter is formed on the outer surface of the display device, it is formed after the display device is completed. Therefore, the heat resistance of the filter material may be low, and an organic material having good chromaticity is used.

The perforated metal plates of the light guide plate and the partition plate are stacked so as to be in the same position, and assembled together with the back plate so that the cathode and the anode facing the discharge cell intersect.

In FIG. 3A, only the light guide plate is shown.
In FIG. 3B, the MgO protective layer is omitted.

The periphery of the light guide plate and the back plate is sealed with glass to form an airtight container, and after exhausting gas and Ne-Xe (5%) gas enclosed by the chip tube formed on the back plate, the chip is turned off. Completed PDP.

A driving timing chart of this PDP is shown in FIG. An alternating voltage independent of the address signal is applied to the perforated metal plates M1 and M2. The voltage width of both electrodes can be kept lower than the discharge start voltage. When a discharge occurs in the cell in this state, the generated positive and negative charged particles are charged on the dielectric surface of the opposite polarity electrode to form so-called wall charge. The AC voltage reverses the next moment, and the electric field due to the wall charges and the electric field due to the wall charges are superposed, so that the discharge also occurs. When an AC voltage is applied, this relationship is repeated and the discharge continues. That is, memory is performed. If no discharge is generated, the wall charge is weak and no new discharge occurs. Such an operation is independent and not directly related to the address electrode.

The selective writing of this PDP is performed as follows. Exposed electrode close to the AC electrode, M1 in FIG.
The on-pulse of each of the A and the cathode of
The C electrode is applied at the same timing as that of the adjacent exposed electrodes. This pulse wave height is made larger than the AC voltage wave height. As a result, the electric field between the AC electrodes is strengthened and discharge is generated. At this time, the pulse height is set so that the electric field at the start of discharge does not reach with the ON pulse of the cathode or the anode alone, and reaches only when the both pulses overlap. In this way, discharge can be excited in any cell. In this embodiment, such a method is adopted.

Other writing methods are possible. A voltage higher than the discharge start voltage may be applied between the cathode and the anode. In this method, the write timing can be at any position. However, it has the disadvantage of requiring a higher voltage.

The erasing operation is performed simultaneously with the scanning lines. Although the cathode is used as the scanning line in FIG. 4, it may of course be a cathode. When the memory discharge M1 is in the negative pulse state, the ON pulse is applied to the cathode. Then, the positively charged particles generated by the discharge flow to the cathode and are neutralized. Therefore, the wall charge in the vicinity of the AC electrode becomes small, and the next discharge does not occur, and the erase can be performed. In order to ensure this erase operation, an on-pulse may be applied to all the anode side lines. However, it is limited to a range that does not adversely affect the memory discharge of other scan line cells. In this embodiment, such a method is adopted.

Other erasing methods are possible. A short on-pulse may be applied to the cathode at the timing when the positive wall charges are accumulated on the surface of the M1 coated dielectric. As a result, discharge is generated by the cathode and the wall charge, and part of the charge is neutralized by the cathode and the pulse is short, so that new wall charge of opposite polarity cannot be formed and AC discharge is stopped. Since this method requires the generation of short pulses, it has some problems in driving. With the above driving method, the memory operation of the PDP was confirmed.

As can be seen from FIG. 3, the light guide plate of the present invention can be applied to various PDPs. For example, in the case where the perforated metal plate M2 of the partition plate is not used as an electrode, or in the case where the partition wall is composed only of a dielectric, the perforated metal plate M1 of the light guide plate is replaced with a conventional discharge inducing electrode, so-called trigger electrode. The DC type PDP can be constructed. Of course, a PDP which does not use M1 as an electrode is also possible. Furthermore, an AC type PDP using an electrode covered with a dielectric material can be constructed as an address electrode.

Although the PDP has been described in this embodiment,
It is also clear that the light guide plate of the present invention can be applied to display devices other than PDPs.

In this embodiment, the color filter is formed on the outer surface of the light guide plate, but it is needless to say that the color filter can be formed inside the light guide plate. The color filter may be formed separately from the light guide plate, or the second dielectric may be formed of colored transparent glass so that the light guide plate itself has a filter performance.

[0057]

According to the present invention described above, the following effects can be obtained.

(1) Since a large number of light guide paths can be collectively formed in the thickness direction, the light guide plate is inexpensive.

(2) By forming the light guide plate from a perforated metal plate, a fine light guide path can be formed accurately.

(3) For the same reason as (2) above, thin glass is reinforced and the light guide plate can be made thin. Therefore, a thin and lightweight display device can be obtained.

(4) Since the reflectance of the first dielectric can be increased, the light guide plate has high performance.

(5) Since the light guide plate has good heat resistance and airtightness, it can be used as a front plate which is a container for various display devices.

(6) If a light guide plate is used for the front plate of the display device, the color filter can be formed outside the device. Therefore, the heat resistance of the filter material may be low, and since the material selection range is wide, a filter having high chromaticity can be used.

(7) Since the perforated metal plate of the light guide plate can be used as an electrode of the PDP, an extra electrode forming step can be omitted, and this electrode does not hinder the display.

[Brief description of the drawings]

FIG. 1 is a partial schematic plan view of a light guide plate.

FIG. 2 is a sectional view of FIG.

FIG. 3 is a schematic plan view and a sectional view of a PDP used in an example.

FIG. 4 is a drive timing chart.

[Explanation of symbols]

LG: light guide plate, M1, M2: perforated metal plate, D: coated dielectric, D1: first dielectric, D2: second dielectric, BP:
Back plate, K: cathode, A: anode, PW: partition plate, P: phosphor, F: color filter, C: display discharge cell.

Claims (6)

(57) [Claims] 1. A perforated metal plate having a plurality of light guides in the thickness direction and having through holes corresponding to the light guides is provided at positions where different light guides are separated, and the through holes are filled with transparent glass. Discharge display device using a perforated metal plate of a light guide plate which is a hermetically sealed body as an electrode. 2. The method according to claim 1, wherein the surface of the perforated metal plate is covered with a first dielectric while maintaining the through holes, and the through holes are filled with transparent glass which is a second dielectric. Discharge display device. 3. The first dielectric, which has a higher fire resistance than the second dielectric, is made of an inorganic material containing glass, and has a coating thickness of 2 to 50 μm and a surface reflectance of 50% or more. The discharge display device according to claim 2. 4. The transparent glass, which is the second dielectric,
The discharge display device according to claim 2, wherein the plurality of light guide paths are colored in a plurality of colors. 5. The discharge display device according to claim 1, wherein the light guide plate is used as a display surface of a display device, and color filters of a plurality of colors are formed on an outer surface of the display surface. 6. A display device in which the light guide plate used in the discharge display device according to claim 1 is used as a display surface which is a part of a display device container.