JP2006031950A - Plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma display panel having a reflection layer which restricts generation of an impurity gas and prevents a discharge starting voltage from rising. <P>SOLUTION: It is considered that a pack density of white pigment powder becomes small and an amount of adsorption of the impurity gas becomes small when a BET specific surface area of the white pigment powder is smaller than a certain value. Therefore, if the reflection layer is formed of the white pigment powder having the BET specific surface area of 6 m<SP>2</SP>/g or less, the generation of the impurity gas is restricted and the discharge starting voltage is not allowed to rise. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma display panel known as a thin image display device.

  The plasma display panel is a flat display that displays an image by exciting and emitting phosphors with ultraviolet rays generated by gas discharge. The plasma display panel is classified into a transmission type and a reflection type depending on how light is extracted from the phosphor layer that has emitted light. Since the transmissive type extracts light through the phosphor layer, a part of the visible light is absorbed and reflected by the phosphor layer, and the luminance is lowered. In contrast, the reflection type can directly extract light from the front surface of the phosphor layer, and light directed toward the back surface is reflected and extracted by the phosphor layer, resulting in high brightness.

However, even in such a reflection type plasma display panel, the reflection of the phosphor layer is not sufficient, and a configuration in which a reflection layer is provided inside the partition wall on the back side of the phosphor layer is disclosed in order to increase the luminance. Has been. Here, as the reflective layer, a white pigment layer in which fine powders of white pigments such as titanium oxide (TiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) are filled with high density has been proposed (for example, Patent Document 1). .
Japanese Patent No. 2773393

However, the fine powder of the white pigment as described above easily adsorbs moisture (H ₂ O) and carbon dioxide (CO ₂ ), and has adsorbed a large amount of H ₂ O and CO ₂ . During the gas discharge, impure gases such as H ₂ O and CO ₂ adsorbed on the surface are released from the reflective layer. Then, the released impurity gas is adsorbed by the protective film or the like, and as a result, the discharge characteristics are lowered, and there is a problem that the discharge start voltage is raised.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a plasma display panel including a reflective layer that suppresses generation of impure gas and prevents an increase in discharge start voltage. To do.

The present invention is a plasma display panel in which a reflective layer and a phosphor layer are sequentially formed on a substrate, and the reflective layer is formed of white pigment powder having a BET specific surface area of 6 m ² / g or less. This is the configuration.

By setting the specific surface area of the white pigment powder to a certain value or less in this way, the amount of H ₂ O or CO ₂ impure gas adsorbed on the surface of the white pigment powder can be reduced, and an increase in the discharge start voltage can be prevented. As the surface area of the white pigment powder is larger, the impure gas is adsorbed. Therefore, the surface area of the white pigment powder in contact with the impure gas is preferably smaller. Even if the volume and weight are the same, the surface area of the material with more irregularities on the surface is larger, and the surface area with respect to the volume is smaller as the material is more spherical. Thus, since the surface area of a substance is related to the volume, weight, and shape of the substance, the BET specific surface area, which is the surface area per unit weight, was used as an index. As a result, when the BET specific surface area of the white pigment powder constituting the reflective layer is 6 m ² / g or less, the adsorption amount of H ₂ O and CO ₂ becomes a certain amount or less, and an increase in the discharge start voltage can be prevented.

  The white pigment powder of the plasma display panel of the present invention may have an average particle size of 0.3 μm or more and 1.2 μm or less.

  By setting it as the range of the average particle diameter of such a white pigment powder, the reflectance is increased and a high-luminance plasma display panel is obtained. As the average particle size of the white pigment powder decreases, the packing density increases and the reflectance increases. However, when the average particle size is smaller than 0.3 μm, the reflected light falls below the lower limit wavelength range (0.3 μm) of visible light. The light will disappear.

Further, the white pigment powder of the plasma display panel of the present invention includes titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), barium titanate (BaTiO ₃ ), zinc oxide (ZnO), it may include at least one selected from the group consisting of magnesium aluminate (MgAl ₂ O _4).

  Such a white pigment powder can be easily processed in shape, can have a small BET specific surface area, and can have an appropriate particle size.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of impure gas can be suppressed and the plasma display panel which prevented the raise of the discharge start voltage can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a perspective view showing a main configuration for explaining a plasma display panel according to an embodiment of the present invention. The front substrate 10 having a transparent and insulating front glass substrate 14 as a base material and the rear substrate 40 having a rear glass substrate 44 as a base material are disposed to face each other.

  On the front substrate 10, display electrodes 28 including scanning electrodes 24 and sustaining electrodes 26 arranged in parallel are formed with a predetermined pitch and a predetermined number arranged in stripes. Here, the scanning electrode 24 and the sustain electrode 26 are composed of transparent electrodes 24a and 26a and bus electrodes 24b and 26b made of silver electrodes or the like and having a narrower width than the transparent electrodes 24a and 26a. A light shielding layer 30 is formed between the display electrodes 28 to improve contrast. A first dielectric layer 32 that covers the display electrode 28 and the light shielding layer 30 and has a current limiting function is formed. Further, a protective layer 34 is formed on the first dielectric layer 32 so that the first dielectric layer 32 is not sputtered by plasma discharge.

  On the rear substrate 40, data electrodes 54 arranged in parallel for writing image data are arranged and formed so as to intersect the display electrodes 28 of the front substrate 10. Then, the second dielectric layer 56 is formed so as to cover the data electrode 54. Thereafter, a plurality of partition walls 58 are formed substantially in the center between the data electrodes 54 in parallel with the data electrodes 54. Further, as shown in FIG. 2, a reflective layer 59 is formed between the side surface of the partition wall 58 and the partition wall 58, and a phosphor layer 60 that emits red, green, and blue light is formed on the reflective layer 59. Yes.

Next, a method for manufacturing the front substrate 10 and the rear substrate 40 will be described. The transparent electrodes 24a and 26a are formed by printing, baking, sputtering or the like using a transparent conductive material such as indium tin oxide (ITO) or tin oxide (SnO ₂ ). Since the transparent conductive material alone has a high resistance, bus electrodes 24b and 26b are formed on the transparent electrodes 24a and 26a. The bus electrodes 24b and 26b are formed of a single-layer film such as silver (Ag), aluminum (Al), or copper (Cu) having a low resistance, or a two-layer structure of chromium (Cr) and Cu, or of Cr, Cu, and Cr. A laminated film such as a three-layer structure is formed by printing, a firing method, sputtering, or the like. The light shielding layer 30 is formed by mixing a black pigment such as Cr with glass frit to make a paste, baking after patterning.

The first dielectric layer 32 is formed by applying a dielectric paste, for example, with a die coater and drying it, and then firing it in a firing furnace. Examples of the dielectric paste material include so-called (PbO—) containing, for example, lead oxide (PbO), silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), zinc oxide (ZnO), barium oxide (BaO), and the like. A low-melting glass paste having a (SiO ₂ —B ₂ O ₃ —ZnO—BaO) glass composition can be used. Alternatively, a glass paste containing as a main component at least one of PbO, bismuth oxide (Bi ₂ O ₃ ), and phosphorus oxide (PO ₄ ) can also be used. Further, since the protective layer 34 is required to be a material excellent in sputtering resistance, magnesium oxide (MgO) is often used and is formed by an electron beam evaporation method, a sputtering method, an ion plating method, or the like. .

The data electrode 54 can be formed by the same material and film formation method as the bus electrodes 24 b and 26 b of the front substrate 10. The second dielectric layer 56 can be formed by the same material and film formation method as the first dielectric layer 32, or a white pigment such as titanium oxide (TiO ₂ ) may be mixed as a filler. .

  The partition wall 58 is formed with a predetermined thickness of about 100 μm by screen printing a glass paste a plurality of times. The reflective layer 59 is formed of white pigment powder, and the forming material and forming method will be described in detail later. For the phosphor layer 60, phosphors that emit red, green, and blue light can be formed on the reflective layer 59 by, for example, an inkjet method.

  Thereafter, when the front substrate 10 and the back substrate 40 are overlapped and joined, a discharge space surrounded by the barrier ribs 58, the protective layer 34, and the phosphor layer 60 is generated. Then, the plasma in the discharge space is exhausted, and a mixed gas of neon (Ne) and xenon (Xe) is sealed at a pressure of about 66.5 kPa to complete the assembly process and display a color image. It becomes a panel.

Next, the forming material and forming method of the reflective layer 59 of the present invention will be described. As a material of the reflective layer 59, a white pigment having a large refractive index, for example, TiO ₂ is preferable. The fine powder of TiO ₂ is produced by, for example, a gas phase chemical method. That is, titanium chloride (TiCl ₄ ) is fired at a high temperature to obtain spherical and fine powdered TiO ₂ . Thus, the surface area per volume can be minimized by using spherical fine powder. The specific surface area of the TiO ₂ fine powder can be controlled by performing, for example, annealing. Porous materials such as TiO ₂ have large surface irregularities and a large specific surface area. Therefore, if TiO ₂ is annealed at around 1000 ° C., the surface irregularities are reduced and the specific surface area is lowered. Thus, the specific surface area of TiO ₂ can be controlled by changing the annealing temperature and time.

Moreover, the particle size of the TiO ₂ fine powder can be made uniform by filtering. Then, the organic binder ethyl cellulose and the solvent α-terpineol are kneaded with such a fine TiO ₂ powder with a bead mill to form a paste, which is formed to a predetermined thickness by screen printing to form the reflective layer 59.

Here, in addition to TiO ₂ , Al ₂ O ₃ , SiO ₂ , BaTiO ₃ , ZnO, and MgAl ₂ O _{4 which} are white pigments having a large refractive index are preferable, and at least one of these is selected. Alternatively, TiO ₂ may be included in the selected one.

  Hereinafter, in order to evaluate the performance of the plasma display panel of the present invention, a plasma display panel based on the above-described embodiment is manufactured, and a result of an experiment of performing a performance evaluation experiment on the plasma display panel is shown.

(Example)
15 samples with different combinations of BET specific surface area and average particle diameter of TiO ₂ , Al ₂ O ₃ , SiO ₂ , BaTiO ₃ , ZnO as white pigment powders, and 3 samples for comparison, 18 samples in total were prepared. A plasma display panel was prepared for each sample. And the discharge start voltage of each plasma display panel, the moisture generation amount in a plasma display panel, and the reflectance of 550 nm of the fluorescent substance surface were measured.

  First, white pigment powders having different specific surface areas were formed by the method described above. And the BET specific surface area of each white pigment powder was measured by the BET 1-point method. Thereafter, a reflective layer 59 was formed with white pigment powder having the same BET specific surface area, and a plasma display panel was produced. Moreover, the average particle diameter of the white pigment powder of each BET specific surface area was measured by the laser diffraction method. The amount of moisture generated in the plasma display panel was measured by temperature programmed desorption gas spectroscopy (TDS).

And about the plasma display panel produced with each sample, characteristic values, such as a discharge start voltage, were measured. The discharge start voltage was applied by gradually increasing the AC pulse voltage to the scan electrodes and sustain electrodes on the front substrate, and the lowest voltage at which discharge was started at some point in the plasma display panel was measured first. The discharge start voltage increases as the amount of H ₂ O or CO ₂ impure gas in the plasma display panel increases. Here, the discharge start voltage and the moisture generation amount are shown as relative values. The reflectance on the phosphor surface is a value measured at a wavelength of 360 nm to 740 nm with a spectrocolorimeter and a value of 550 nm is shown as a representative value. These measured values are shown in Table 1.

  As shown in Table 1, regardless of the type of white pigment powder, when the BET specific surface area is small, the amount of water generated in the plasma display panel is also small, and the discharge start voltage is also low. Further, the average particle diameter of the white pigment powder is around 0.5 μm, and the reflectance shows a peak value.

FIG. 3 is a diagram showing the relationship between the BET specific surface area of Table 1 and the amount of water generation (relative value) in the plasma display panel. As the BET specific surface area increases, the amount of moisture generated in the plasma display panel increases. However, if the amount is 6 m ² / g or less, the amount of moisture generated in the plasma display panel is small. Therefore, if the reflective layer is made of white pigment powder having a BET specific surface area of 6 m ² / g or less, the generation of impure gas is suppressed, so that the discharge start voltage does not increase. Here, the preferable range of the BET specific surface area that can prevent the increase of the discharge start voltage is 2 m ² / g or more and 5 m ² / g or less.

  FIG. 4 is a diagram showing the relationship between the average particle diameter of the white pigment powder and the reflectance of the phosphor surface. As the average particle size of the white pigment powder decreases, the packing density increases and the reflectance also increases. When the average particle size is around 0.5 μm, the reflectance of the phosphor surface becomes the highest, and when the particle size is smaller than that, the reflectance of the phosphor surface rapidly decreases. This is because the particle size is smaller than the wavelength. Since the lower limit of visible light is about 300 nm, the lower limit of the particle diameter giving the reflectance data is 0.3 μm. Here, the preferable range of the average particle diameter in which the reflective layer exhibits high reflectivity is 0.3 μm or more and 1.0 μm or less.

Note that even when the reflective layer is formed of MgAl ₂ O ₄ powder, the BET specific surface area is 6 m ² / g or less, and in particular, an increase in the discharge start voltage can be prevented, and the average particle size is 0.3 μm or more and 1.2 μm. Below, the reflectance was in a high range.

  The plasma display panel of the present invention is useful for a plasma display panel without suppressing the release of impure gas and without increasing the discharge start voltage.

The perspective view which shows the main structures of the plasma display panel in embodiment of this invention Enlarged view of the vicinity of the reflective layer of the plasma display panel in the embodiment of the present invention The figure which shows the relationship between the BET specific surface area and water generation amount of embodiment of this invention The figure which shows the relationship between the average particle diameter of the white pigment powder of embodiment of this invention, and the reflectance of a fluorescent substance surface

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Front substrate 14 Front glass substrate 24 Scan electrode 24a, 26a Transparent electrode 24b, 26b Bus electrode 26 Sustain electrode 28 Display electrode 30 Light-shielding layer 32 First dielectric layer 34 Protective layer 40 Back substrate 44 Back glass substrate 54 Data electrode 56 Second dielectric layer 58 Partition wall 59 Reflective layer 60 Phosphor layer

Claims (3)

A plasma display panel in which a plurality of barrier ribs and a reflective layer and a phosphor layer are sequentially formed between the barrier ribs on a substrate, wherein the reflective layer is formed of a white pigment powder having a BET specific surface area of 6 m ² / g or less. A plasma display panel characterized by The plasma display panel according to claim 1, wherein the white pigment powder has an average particle size of 0.3 μm or more and 1.2 μm or less. The white pigment powder includes titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), barium titanate (BaTiO ₃ ), zinc oxide (ZnO), and magnesium aluminate (MgAl ₂ O _4). 3. The plasma display panel according to claim 1, comprising at least one selected from the above.

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