JP3640495B2 - Plasma display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display panel. More specifically, the present invention relates to a plasma display panel that can be suitably used for an AC-driven surface discharge type plasma display panel.
[0002]
[Prior art]
In recent years, there has been a growing demand for thinner and larger display screens in display devices. Among various display devices, a plasma display panel (hereinafter referred to as “PDP”) is thin, easily colored and large in area, is self-luminous, and has excellent visibility. Therefore, for example, it is expected as the most promising candidate for a large-screen wall-mounted television.
[0003]
A PDP is a display device in which a discharge space is formed inside by arranging a pair of substrates facing each other with a minute gap and sealing the periphery. In addition, a phosphor that emits light of a desired color by being excited is disposed in the discharge space. Here, since this phosphor is generally made of white powder, there is a problem that the entire screen is whitened under illumination such as a fluorescent lamp, and the contrast ratio of the display image is lowered.
[0004]
In order to solve this problem, providing a color filter is reported in, for example, Japanese Patent Application Laid-Open No. 7-21924. The PDP described in this publication is provided with a color filter corresponding to the emission color of the phosphor for each phosphor. In the PDP described in this publication, a reduction in contrast due to light scattered by a white phosphor can be reduced.
[0005]
[Problems to be solved by the invention]
In the PDP described in the above publication, a color filter obtained by adding a pigment for transmitting light of a desired color to a dielectric made of low-melting glass is formed on a substrate and electrodes by a printing method. When the color filter is formed directly on the electrode in this way, the pigment contained in the color filter is generally an oxide of a transition metal, and therefore the pigment is reduced by the current applied to the discharge electrode during use. This reductant of the pigment may deteriorate the insulation between the electrodes and cause a short circuit between the electrodes.
[0006]
[Means for Solving the Problems]
Thus, according to the present invention, in the plasma display panel comprising a plurality of discharge electrodes on the front substrate and a dielectric layer covering each of the discharge electrodes, and the phosphor layer disposed on the back substrate, the dielectric Ri Na by disposing a color filter layer that transmits light of a color corresponding to the emission colors of the phosphor layers in the layer, the dielectric layer is comprised of upper dielectric layer and the lower dielectric layer, the upper dielectric layer The plasma display panel is characterized in that includes 40 to 60% by weight of lead oxide and the lower dielectric layer includes 35 to 50% by weight of lead oxide .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
One feature of the present invention is that a color filter layer is provided in a dielectric layer provided on a front substrate. Here, in addition to the configuration of the present invention, a color filter layer may be provided at a position in contact with the discharge electrode, on the protective layer, and between the dielectric layer and the protective layer. First, when it is provided at a position in contact with the discharge electrode, the color filter layer is reduced by an alternating electric field applied to the discharge electrode. The generated reductant may deteriorate the insulation between the discharge electrodes and cause a short circuit. In the case of the protective layer and between the dielectric layer and the protective layer, the color filter layer is reduced by the collision of ions generated by the discharge, and the reduced body increases the conductivity of the surface of the dielectric layer. The increase in the conductivity hinders the accumulation of charged particles on the surface of the dielectric layer, so that the memory effect disappears. Therefore, the color filter layer needs to be provided in the dielectric layer.
[0008]
The PDP of the present invention can be suitably used particularly for an AC drive type surface discharge type PDP. In addition, the PDP of the present invention can be applied to both a reflection type and a transmission type display format.
The substrate that can be used in the present invention is not particularly limited, and examples thereof include a glass substrate, a quartz substrate, and a silicon substrate. Among these, the glass substrate is preferable because it is inexpensive.
[0009]
Next, a discharge electrode (display electrode) is formed on the front substrate. A plurality of display electrodes (also referred to as sustain electrodes) are formed in stripes at predetermined intervals. The material which can be used for a discharge electrode is not specifically limited, A well-known electrode material can be used. For example, Ag, Au, Al, Cu, Cr and their laminates, metal oxides such as ITO, and the like can be given. Of these, a three-layer structure of Cr / Cu / Cr is preferable. The display electrodes preferably have a thickness of 1 to 1.5 μm, a width of 50 to 100 μm, and a pitch of 200 to 400 μm. In addition, as a formation method of an electrode, all well-known methods, such as a vapor deposition method, can be used, for example.
Here, the display electrode may have a so-called two-layer structure of a bus electrode and a transparent electrode. It is preferable to use a Cr / Cu / Cr three-layer structure for the bus electrode and ITO for the transparent electrode.
[0010]
Next, a dielectric layer is formed so as to cover the display electrodes.
Here, the material that can be used for the dielectric layer is not particularly limited as long as it can accumulate charges when using the PDP. Accordingly, known materials can also be used. For example, when a glass substrate is used as the substrate, a low melting point glass paste composed of a low melting point glass powder and a resin binder can be used. Examples of the low melting point glass powder include PbO—SiO ₂ —B ₂ O ₃ series, PbO—SiO ₂ —B ₂ O ₃ —ZnO series, PbO—B ₂ O ₃ —ZnO series, Bi ₂ O ₃ —SiO ₂ —B. Examples thereof include powders of materials such as ₂ O ₃ . The low melting point glass powder may contain R ₂ O (R = Li, Na, K, etc.), BaO, CaO, MgO, TiO ₂ , ZrO ₂ , Al ₂ O ₃ , NaF, P ₂ O _5, etc. Good. Examples of the resin binder include α-terpineol, butyl carbitol, butyl carbitol acetate, ethyl cellulose, acrylic polyvinyl acetate polybutyral, and the like. These low-melting glass powder and resin binder may be appropriately combined according to the properties of the substrate and dielectric layer used. Furthermore, you may add a refractive index regulator, a filler, etc.
[0011]
Examples of the method for forming the dielectric layer include a method in which a desired thickness is applied by screen printing or the like and then fired.
Here, in the present invention, a color filter layer is formed in the dielectric layer. The method for forming the color filter layer is not particularly limited. For example, a method in which a lower dielectric layer, a color filter layer, and an upper dielectric layer are stacked in this order and sandwiched between two dielectric layers is exemplified. The upper dielectric layer and the lower dielectric layer preferably have a thickness of 15 to 25 μm and 8 to 15 μm, respectively. If the upper dielectric layer and the lower dielectric layer are thicker than the above thickness, the operating voltage becomes high, which is not preferable. On the other hand, if the upper dielectric layer and the lower dielectric layer are thinner than the above thickness, it is not preferable because it becomes difficult to apply by a method such as screen printing.
[0012]
Further, when the dielectric layer is divided into two layers, it is preferable to use a material in which the upper dielectric layer has a softening point lower than that of the lower dielectric layer. This is because the lower dielectric layer is subjected twice to heat treatment for firing. Specifically, the softening point of the upper dielectric layer is preferably 470 to 510 ° C., and the softening point of the lower dielectric layer is preferably 510 to 570 ° C. The softening point can be adjusted as appropriate by adjusting the components constituting the dielectric layer.
[0013]
Furthermore, when the dielectric layer is divided into two layers, it is preferable to reduce the proportion of lead oxide contained in the dielectric layer from the conventional level (about 70% by weight). Specifically, the upper dielectric layer is preferably 60% by weight or less (more preferably 40 to 60% by weight), and the lower dielectric layer is preferably 50% by weight or less (more preferably 35 to 50% by weight). If the ratio of lead oxide is larger than the above ratio, the light transmittance of the color filter layer is not preferable.
[0014]
The color filter layer can be formed, for example, by applying a paste containing pigment particles by screen printing and baking. The thickness of the color filter layer is preferably 2 to 5 μm. In the case of red, pigment particles include particles of copper sulfate, alkali metal salts, etc., in the case of green, particles of copper sulfate, chromium oxide, cobalt oxide, etc., and in the case of blue, particles of cobalt compounds, etc. Is mentioned. Further, these pigments are preferably wrapped with a heat-resistant material such as SiO ₂ and / or MgF ₂ . This is because when the pigment particles come into contact with the low melting point glass of the dielectric layer, lead oxide, which is the main component of the low melting point glass powder, and the pigment particles undergo an oxidation / reduction reaction, and the color of the color filter layer becomes light. is there. The heat resistant material has a function of suppressing the oxidation / reduction reaction. Examples of a method for coating the pigment particles with a heat resistant material include a sol-gel method.
[0015]
A protective film is preferably formed on the dielectric layer by a CVD method, a sputtering method, or the like to protect against damage caused by ion collision caused by discharge. The protective film is made of, for example, MgO, CaO, SrO, BaO or the like. The thickness of the protective film is preferably 0.5 to 1 μm.
Here, it is preferable to provide grid-like ribs on the front substrate so as to surround a region (discharge cell) where the discharge electrodes on the rear substrate intersect. When the color filter layer is formed by a screen printing method, undulations are usually formed at the ends thereof. Although this undulation lowers the display quality, the lattice ribs serve to hide the undulation portion. For the grid ribs, for example, a grid rib forming material made of a low melting glass paste containing a low melting glass powder and a resin binder (these can be the same as the above dielectric layer) is applied to a desired thickness. Then, it can be formed by selectively removing by a sandblasting method using a mask having a desired pattern and further baking. Moreover, it is also possible to form by repeating the application | coating by a screen printing method in multiple times, forming in a desired pattern, and baking.
[0016]
Next, at least a phosphor layer is disposed on the back substrate.
Here, the board | substrate which can be used can use the same thing as the said front substrate. In addition, when providing the electrode only for an address on a back substrate, it is preferable to make it orthogonal to the discharge electrode (display electrode) on a front substrate.
Next, the phosphor layer is preferably formed in a stripe shape so as to cover the rib wall surfaces including the address electrodes between the partition walls (ribs) formed on the back substrate. The barrier ribs are generally formed in stripes in the same direction as the address electrodes on the back substrate. Its height is about 100 to 200 μm. The partition wall forming method is selected, for example, by a sandblasting method using a mask having a desired pattern after applying a partition wall forming material made of a low melting point glass paste containing a low melting point glass powder and a resin binder to a desired thickness. It can be formed by removing the substrate and firing it further. Moreover, it is also possible to form by repeating the application | coating by a screen printing method in multiple times, forming in a desired pattern, and baking.
[0017]
The phosphor layer can be applied and formed by a known method such as a screen printing method.
Note that a dielectric layer may be formed so as to cover the address electrodes and the back substrate before the phosphor layer and the barrier ribs are formed. The method for forming the dielectric layer is not particularly limited, and any known method can be used. For example, a low melting point glass paste containing a low melting point glass powder and a resin binder is applied by a screen printing method or the like so as to have a desired thickness, and then fired.
[0018]
A PDP can be formed by stacking the front substrate and the rear substrate so that the display electrodes and the address electrodes are orthogonal to each other and hermetically sealing the periphery. In this superposition, the partition wall and the protective layer, and the partition wall and the grid rib may be bonded using an adhesive. Note that the space between the substrates is preferably filled with a discharge gas such as Ne or Xe.
The color filter layer is preferably composed of a layer that transmits light of a color emitted from the phosphor layer. The color filter layer is a layer that transmits light of red, green, and blue colors, and the phosphor layer is a layer that emits light of red, green, and blue colors. The full color display with a high contrast can be easily performed.
[0019]
【Example】
Next, the present invention will be specifically described based on an example applied to a three-electrode AC type surface discharge panel.
Example 1
A discharge electrode comprising a transparent electrode (ITO, thickness 0.2 μm, width 180 μm, interval 80 μm) 2 and a bus electrode (Cr / Cu / Cr, thickness 2 μm, width 70 μm) 3 on a front substrate (glass substrate) 1. The layers were laminated in this order.
[0020]
Next, a paste containing a low-melting glass powder (softening point 510 ° C.) was applied to the entire surface, and baked at 580 ° C., thereby laminating 10 μm of the lower dielectric layer 4. A color filter layer 5 that transmits red, green, and blue light was formed in this order on the lower dielectric layer 4 by applying a paste containing pigment particles by screen printing and baking. Further, a paste containing a low-melting glass powder (softening point 480 ° C.) was applied to the entire surface, and baked at 580 ° C., thereby laminating the upper dielectric layer 6 by 20 μm. Furthermore, a front substrate could be formed by forming a protective film 7 made of MgO on the upper dielectric layer 6 with a thickness of 1 μm.
[0021]
Next, address electrodes (Cr / Cu / Cr, thickness 2 μm, width 70 μm, interval 120 μm) 9 were formed on the rear substrate (glass substrate) 8 by vapor deposition and photolithography.
A partition material layer was formed by applying a low melting point glass paste on the entire surface of the substrate 8. A mask having a desired pattern was formed on this partition wall material layer, and calcium carbonate particles were sprayed (sand blasting method) to remove the partition wall material layer other than under the mask. After the removal, the partition wall 10 was formed by firing at 550 ° C.
[0022]
Next, the back substrate could be formed by applying the stripe-like phosphor layers 11 emitting red, green and blue light in this order between the barrier ribs 10 by screen printing.
The obtained front substrate and rear substrate are overlapped so that the address electrode 8, the transparent electrode 2 and the bus electrode 3 are orthogonal to each other, and the periphery is hermetically sealed, whereby the AC drive type 3 shown in FIG. An electrode surface discharge type PDP could be prepared. The space formed by the partition walls between the substrates was filled with Ne (containing 4% by volume of Xe) discharge gas, and the internal pressure was 500 Torr.
[0023]
Example 2
A PDP shown in FIG. 2 was formed in the same manner as in Example 1 except that the following steps were further performed.
A low melting point glass paste was applied on the protective film 7 of the front substrate of Example 1 to form a lattice-like rib forming material layer. On this grid-like rib material layer, a mask having a pattern surrounding the region where one and the other discharge electrodes intersect was formed, and by spraying calcium carbonate particles, the grid-like rib material layer other than under the mask was removed. . After removal, the lattice ribs 12 were formed by firing at 500 ° C.
[0024]
Example 3
A PDP was formed in the same manner as in Example 1 except that pigment particles wrapped with a heat resistant material were used.
According to the PDP of this example, the oxidation / reduction reaction between the pigment particles contained in the color filter layer and the lead oxide contained in the low melting point glass paste of the dielectric layer could be suppressed.
[0025]
【The invention's effect】
The PDP of the present invention is characterized in that a color filter layer is provided in a dielectric layer covering the discharge electrode.
Therefore, it is possible to provide a high-contrast PDP that can prevent reduction due to application of an alternating current of the pigment contained in the color filter, and that does not cause deterioration of insulation between the discharge electrodes and short circuit between the discharge electrodes. it can.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a PDP of Example 1. FIG.
FIG. 2 is a schematic cross-sectional view of a PDP according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 8 Board | substrate 2 Transparent electrode 3 Bus electrode 4 Lower dielectric layer 5 Color filter layer 6 Upper dielectric layer 7 Protective layer 9 Address electrode 10 Partition 11 Phosphor layer 12 Grid-like rib

Claims (6)

In a plasma display panel comprising a plurality of discharge electrodes on a front substrate and a dielectric layer covering each discharge electrode, and the phosphor layer is disposed on the back substrate, a phosphor layer is formed in the dielectric layer. Ri Na by disposing a color filter layer that transmits light of a color corresponding to the emission color, the dielectric layer is comprised of upper dielectric layer and the lower dielectric layer, the upper dielectric layer is 40 to 60 wt% A plasma display panel comprising lead oxide, wherein the lower dielectric layer contains 35 to 50% by weight of lead oxide .   The phosphor layer is formed by periodically arranging stripe-like layers showing red, green and blue emission colors, and the color filter layer is arranged in stripes corresponding to the emission colors of the phosphor layers. The plasma display panel according to claim 1.   A plurality of parallel striped ribs are provided on the back substrate, and red, green, and blue phosphor layers are disposed in a plurality of grooves formed between the two ribs, respectively. 3. The plasma display panel according to claim 2, wherein a boundary line of the color filter layer corresponding to blue and blue is positioned immediately above the rib. Upper dielectric layer, according to claim 1 to 3 of any one of a plasma display panel comprising a material having a lower softening point than the lower dielectric layer. The plasma display panel according to any one of claims 1 to 4 , wherein the color filter layer includes pigment particles wrapped in a heat resistant material. Heat resistant material, a plasma display panel of claim 5 which is a SiO _2, MgF ₂ or mixtures thereof.

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