JP2009134921A - Plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma display panel which can show excellent image display performance. <P>SOLUTION: The plasma display panel comprises a front panel 2 forming a dielectric layer 7 so as to cover a display electrode 6 formed on a substrate and forming a protective film 8 on the dielectric layer 7, and a back panel 9 arranged opposite to the front panel 2 so as to form a discharge space 15 and preparing partitions 13 for partitioning the discharge space 15 and forming a phosphor layer 14 between the partitions 13. A group of magnesium oxide particulates 16 made of magnesium oxide particulates having a crystal structure surrounded by a plane (100) and a plane (111) and a group 16 of magnesium oxide particulates made of magnesium oxide particulates having a crystal structure surrounded by the plane (100), a plane (110), and the plane (111) are arranged at a back panel 9 side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma display panel used for various displays.

  In recent years, expectations for high-definition, high-definition, and large-screen televisions such as high-definition and HD-TV are increasing, and display devices using plasma display panels (hereinafter referred to as PDPs) are large, thin, and lightweight. Is attracting attention as a color display device.

  A general AC type PDP is configured by bonding a front panel and a back panel. The front panel is configured by forming a plurality of display electrodes each having a pair of scan electrodes and sustain electrodes on one side of a glass substrate, and sequentially laminating a dielectric layer and a protective layer so as to cover the display electrodes. Yes.

  On the other hand, the back panel is formed by arranging a plurality of data electrodes for writing image data on a glass substrate so as to intersect with the display electrodes of the front panel in a direction orthogonal to the front panel, and covering the data electrodes. The body layer is formed, and a partition wall having a predetermined height is formed on the dielectric layer so as to partition the discharge space. Further, phosphor layers of R, G, and B colors are formed on the surface of the dielectric layer and the side surfaces of the partition wall. It is comprised by forming.

  The front panel and the back panel are arranged so that the display electrode and the data electrode are orthogonal to each other, and each periphery is sealed, and Xe-Ne system or Xe-He system is used as a discharge gas in the internal discharge space. PDP is configured by enclosing the rare gas.

  In the PDP having such a configuration, a display method is used in which an image of one field is driven by being divided into a plurality of subfields in order to display an image.

  Conventionally, in the PDP, in order to improve the contrast ratio by initializing all display cells in the initializing period of each subfield, a ramp waveform in which the voltage-time transition is gently inclined and applied is usually applied to the electrodes. However, the discharge during the ramp-up waveform application during the initialization period has a characteristic that the discharge start voltage tends to be high because there is a discharge in which the data electrode on the back panel side or the phosphor side having a small secondary electron emission coefficient becomes the cathode. is there. For this reason, the occurrence of weak discharge sometimes becomes unstable and strong discharge is generated, which causes a reduction in image display performance.

  In addition, since any one of R, G, and B phosphors having different compositions is used for each discharge cell, there is a variation in secondary electron emission characteristics on the back panel side. There is a problem that variations occur and affect image display characteristics.

Therefore, in order to improve the image display performance, a particulate powder having a secondary electron emission coefficient γ higher than that of the phosphor material constituting the phosphor layer is attached to the phosphor layer of the back panel, and the initialization brightness is increased. Attempts have been made to improve the generation of dots (Patent Document 1).
International Publication No. 2006/038654 Pamphlet

  However, as in the prior art described above, even if a particulate powder having a high secondary electron emission coefficient γ such as MgO fine particles is adhered to the phosphor layer of the back panel, charge adjustment by a weak discharge in the initialization period is usually performed. If the operation is performed as described above, the light emission in the initialization period becomes too strong, which causes a problem of causing a decrease in contrast.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a plasma display panel that exhibits excellent image display performance.

  In order to solve the above problems, the present invention provides a first substrate in which a dielectric layer is formed so as to cover a display electrode formed on the substrate and a protective film is formed on the dielectric layer, and the first substrate is provided with the first substrate. A second substrate that is disposed to face the discharge space so as to form a discharge space and that partitions the discharge space and that has a phosphor layer formed between the barrier ribs, and has a (100) plane on the second substrate side, Magnesium oxide fine particles composed of magnesium oxide fine particles having a crystal structure surrounded by a (111) plane, or magnesium oxide fine particles having a crystal structure surrounded by a (100) plane, a (110) plane, and a (111) plane The magnesium oxide fine particle group which consists of is arrange | positioned.

  In the PDP of the present invention having the above configuration, when ultraviolet light generated in the discharge space reaches the phosphor layer during driving, magnesium oxide (MgO) fine particles having a specific orientation plane filled in the gaps of the phosphor particles are formed. Upon receiving the ultraviolet light, it exhibits excellent secondary electron emission characteristics. Thereby, in the initialization period, abundant secondary electrons are emitted from the phosphor layer toward the discharge space, and weak discharge is smoothly generated. Thereby, an ideal weak discharge is performed, and the generation of an unnecessary strong discharge can be suppressed.

  In addition, a PDP with a reduced drive voltage and lower power consumption can be realized, and a PDP with a high contrast ratio can be realized without generating unnecessary light emission even in charge adjustment by weak discharge in the initialization period.

  In addition, since the MgO fine particles of the present invention emit ultraviolet light with discharge, the phosphor is excited by ultraviolet irradiation by the MgO fine particles in the phosphor layer in addition to the ultraviolet irradiation generated in the discharge space, and efficiently emits visible light. Can result. Here, in the phosphor layer, MgO fine particles surrounding the periphery of the phosphor particles can efficiently excite the phosphor particles from the periphery, and can appropriately reflect visible light while preventing irregular reflection. Light emission can be expected.

  Furthermore, since the MgO fine particles in the present invention have sufficiently high secondary electron emission characteristics as compared with the phosphor, by arranging this in the phosphor layer, it is caused by each phosphor component of each color phosphor layer. Dispersion in discharge characteristics can be made relatively small. As a result, the discharge characteristics can be made uniform among the color discharge cells of the entire PDP, and a stable image display performance is exhibited.

  Hereinafter, although PDP by one embodiment of the present invention is explained, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic cross-sectional view showing a PDP according to an embodiment of the present invention. For the sake of explanation, FIG. 1 schematically shows the MgO fine particle group disposed inside the phosphor layer, which is larger than the actual size.

  As shown in FIG. 1, the PDP 1 is composed of a front panel 2 as a first substrate and a back panel 9 as a second substrate which are disposed with their main surfaces facing each other so as to form a discharge space therebetween. Has been.

First, the front panel 2 is configured as follows. That is, on the main surface of the glass substrate 3, a plurality of pairs of display electrodes 6 including scan electrodes 4 and sustain electrodes 5 arranged with a predetermined discharge gap are arranged, and the display electrodes 6 are covered. A dielectric layer 7 made of low-melting glass mainly composed of lead oxide (PbO), bismuth oxide (Bi ₂ O ₃ ) or phosphorus oxide (PO ₄ ) is formed over the entire main surface of the glass substrate 3 by a screen printing method or the like. Is formed by. The scan electrode 4 and the sustain electrode 5 constituting the display electrode 6 are transparent electrodes 41 and 51 made of a transparent conductive material such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ). On top of this, bus lines 42 and 52 made of Ag, Al or Cr / Cu / Cr laminated film are laminated and formed.

  Further, on the dielectric layer 7, MgO, CaO, Sr, and Ba such as MgO, CaO, SrO, and BaO are used for the purpose of protecting the dielectric layer 7 from ion bombardment during discharge and reducing the discharge start voltage. A protective film 8 made of a material selected from oxides, AlN, BN, diamond, HfN, HfC, and SiC including at least one of them is formed by a vacuum deposition method, an ion plating method, a CVD method. The front panel 2 is configured by forming a film by a thin film forming method such as the above. In addition, said material which comprises the protective film 8 is a material with a high ion induced secondary electron yield ((gamma)).

On the other hand, the back panel 9 is formed by forming data electrodes 11 made of Ag, Al, Cr / Cu / Cr laminated film or the like in a stripe shape on one main surface of the glass substrate 10 at regular intervals, and covers the data electrodes 11. Thus, the dielectric layer 12 having a thickness of 30 μm is formed. On the dielectric layer 12, a grid-like barrier rib 13 for partitioning the discharge space is formed in accordance with the gap between the adjacent data electrodes 11, and further on the side surface of the barrier rib 13 and the dielectric layer 12 therebetween. Are formed with phosphor layers 14 corresponding to red (R), green (G), and blue (B) colors for color display. As the phosphor constituting the phosphor layer 14, BAM: Eu is used for the blue phosphor (B) and (Y, Gd) BO ₃ : Eu or Y ₂ O ₃ : Eu is used for the red phosphor (R). In the green phosphor (G), Zn ₂ SiO ₄ : Mn, YBO ₃ : Tb, (Y, Gd) BO ₃ : Tb, and the like are used.

  In the present invention, the MgO fine particle group 16 is disposed on the phosphor layer 14 so as to be exposed on the surface facing the discharge space 15. The MgO fine particle group 16 includes an MgO fine particle group made of MgO fine particles having a crystal structure surrounded by the (100) plane and the (111) plane, or the (100) plane, the (110) plane, and the (111) plane. The MgO fine particle group is composed of MgO fine particles having a crystal structure surrounded by. The MgO fine particles will be described later. The MgO fine particle group 16 is not disposed on the surface of the phosphor layer 14 facing the discharge space, but in the phosphor layer 14, the bottom of the phosphor layer 14, or any region of the partition wall 13. In order to sufficiently exhibit the action of the MgO fine particle group 16, it is desirable that the MgO fine particle group 16 is disposed so as to be exposed on the surface facing the discharge space 15.

  The back panel 9 is configured as described above, and the front panel 2 and the back panel 9 are disposed so that the data electrode 11 and the display electrode 6 are orthogonal to each other, and the outer peripheral edge is sealed with a glass frit, A PDP is configured by sealing a discharge gas composed of an inert gas component containing He, Xe, Ne, or the like at a predetermined pressure in the discharge space. Here, a region where a pair of adjacent display electrodes 6 and one data electrode 11 intersect with each other across the discharge space 15 corresponds to discharge cells (also referred to as “subpixels”) for image display, and adjacent RGB. One pixel is composed of three discharge cells corresponding to the respective colors.

  As shown in FIG. 2, the scan electrode driver 111, the sustain electrode driver 112, and the data electrode driver 113 are electrically connected to each of the scan electrode 4, the sustain electrode 5, and the data electrode 11 of the PDP having the above configuration. Connected to. Here, sustain electrodes 5 are collectively connected to sustain electrode driver 112, and each scan electrode 4 and each data electrode 11 are independently connected to scan electrode driver 111 or data electrode driver 113, respectively.

  In the PDP having the above configuration, a discharge circuit is generated in an arbitrary discharge cell by applying an AC voltage of several tens of kHz to several hundreds of kHz to each display electrode 6 by a driving circuit including the drivers 111 to 113. The phosphor layer 14 is irradiated with ultraviolet rays including a resonance line mainly composed of a wavelength of 147 nm by excited Xe atoms and a molecular beam mainly composed of a wavelength of 172 nm by excited Xe molecules, and the phosphor layer 14 is excited to emit visible light. Then, the visible light passes through the front panel 2 and is emitted to the front surface.

  As an example of this driving method, an in-field time division gradation display method is adopted. In this method, a field to be displayed is divided into a plurality of subfields. Each subfield has (1) an initialization period in which all discharge cells are initialized, and (2) each discharge cell is addressed. A writing period in which a display state corresponding to input data is selected and input, (3) a sustain period in which the discharge cells in the display state display light emission, and (4) an erase period in which wall charges formed by the sustain discharge are erased. There are four periods.

  In each subfield, the wall charge of the entire screen is reset by the initialization pulse in the initialization period, and the wall charge amount necessary for performing the write discharge for selecting the lighting cell in the write period is adjusted, specifically maintained. A part of the wall charge on the electrode is erased, and the wall charge is accumulated on the data electrode. During the writing period, discharge is performed for a certain period of time by performing an address discharge in which wall charges are accumulated only in the discharge cells to be lit, and then applying an alternating voltage (sustain voltage) to all the discharge cells simultaneously in the subsequent discharge sustain period. By maintaining it, the luminescence is displayed.

  Here, FIG. 3 shows an example of a driving waveform in the mth subfield in the field. As shown in FIG. 3, an initialization period, a writing period, a sustain period, and an erasing period are assigned to each subfield.

  The initialization period is to erase the wall charges of the entire screen (initialization discharge) and to perform the write discharge in the write period in order to prevent the influence of the lighting of the discharge cells before that (influence of the accumulated wall charge). This is a period during which the charge amount is adjusted. In the drive waveform example shown in FIG. 3, a higher voltage (initialization pulse) than the data electrode 11 and the sustain electrode 5 is applied to the scan electrode 4 to discharge the gas in the discharge cell. The charges generated thereby are accumulated on the wall of the discharge cell so as to cancel the potential difference between the data electrode 11, the scan electrode 4 and the sustain electrode 5, so that the charges are formed on the protective film 8 and the MgO particle group 16 near the scan electrode 4. Negative charges are accumulated as wall charges. Positive charges are accumulated as wall charges on the surface of the phosphor layer 14 near the data electrode 11 and the surface of the protective film 8 and the MgO fine particle group 16 near the sustain electrode 5. Thereafter, a ramp waveform having a gentle downward slope is applied, and a part of the wall charges on the sustain electrode 5 is erased. By adjusting the wall charges, a predetermined wall potential is generated between the scan electrode 4 and the data electrode 11 and between the scan electrode 4 and the sustain electrode 5.

  The writing period is a period for performing addressing (setting of lighting / non-lighting) of the discharge cell selected based on the image signal divided into subfields. In this period, when the discharge cell is turned on, a voltage (scanning pulse) lower than that of the data electrode 11 and the sustain electrode 5 is applied to the scanning electrode 4. That is, a voltage is applied to scan electrode 4 -data electrode 11 in the same direction as the wall potential, and a data pulse is applied between scan electrode 4 and sustain electrode 5 in the same direction as the wall potential, thereby generating a write discharge. As a result, negative charges are accumulated on the surface of the phosphor layer 14, the protective film 8 near the sustain electrode 5 and the surface of the MgO fine particle group 16, and on the surface of the protective film 8 and the MgO fine particle group 16 near the scan electrode 4. , Positive charges are accumulated as wall charges. Thus, a predetermined wall potential is generated between sustain electrode 5 and scan electrode 4.

  The sustain period is a period in which the discharge state is maintained by enlarging the lighting state set by the write discharge in order to ensure the luminance corresponding to the gradation. Here, a voltage pulse for sustain discharge (for example, a rectangular wave voltage of about 200 V) is applied to each of the pair of scan electrodes 4 and sustain electrodes 5 in a phase different from each other in the discharge cell in which the wall charges exist. As a result, a pulse discharge is generated every time the voltage polarity changes in the discharge cell in which the display state is written.

  By this sustain discharge, a resonance line of 147 nm is emitted from the excited Xe atoms in the discharge space 15, and a molecular beam mainly composed of 173 nm is emitted from the excited Xe molecules. The surface of the phosphor layer 14 is irradiated with the resonance line / molecular beam, and display light is emitted by visible light emission. Then, multi-color / multi-gradation display is performed by a combination of sub-field units for each color of RGB. In a non-discharge cell in which no wall charges are written in the protective film 8, no sustain discharge occurs and the display state is black.

  In the erasing period, a gradual erasing pulse is applied to the scan electrode 4 to erase the wall charges.

  Next, the characteristics of the present invention will be described. In the present embodiment, MgO fine particles having an NaCl crystal structure surrounded by a specific two-orientation plane composed of (100) plane and (111) plane, and (100) MgO fine particles having an Mg crystal structure having a NaCl crystal structure surrounded by a specific three-orientation plane consisting of a plane, a (110) plane and a (111) plane, and having such a specific two-orientation plane and a specific three-orientation plane The MgO fine particle group 16 containing is dispersed inside the phosphor layer 14.

  FIG. 4 is a schematic diagram showing the shape of each MgO fine particle included in the MgO fine particle group 16. The MgO fine particle group 16 is obtained by firing an MgO precursor, and mainly includes four types of MgO fine particles 16a, 16b, 16c, and 16d.

  As shown in FIGS. 4A and 4B, the MgO fine particles 16a and 16b have a NaCl crystal structure surrounded by a specific two-orientation plane composed of two planes, the (100) plane and the (111) plane, respectively. . As shown in FIGS. 4C and 4D, the MgO fine particles 16c and 16d are surrounded by specific three kinds of orientation planes composed of three planes of (100) plane, (110) plane, and (111) plane, respectively. It has a NaCl crystal structure. Here, each shape of the MgO fine particles 16a, 16b, 16c, and 16d is merely an example, and may be a slightly distorted shape. In the present invention, the shape is surrounded by the (100) plane and the (111) plane. MgO fine particles having a crystal structure surrounded by (100) plane, (110) plane, and (111) plane may be used.

  The MgO fine particles will be described in more detail. The MgO fine particles 16a shown in FIG. 4A are hexahedrons having a basic structure, and each of the vertices is cut off to form a truncated tetrahedron 82a. The six-sided octagonal principal surface 81a corresponds to the (100) plane, and the eight-sided triangular top surface 82a corresponds to the (111) plane. Next, the MgO fine particles 16b shown in FIG. 4B are octahedrons having a basic structure, and a truncated surface 81b is formed by cutting off each vertex. The hexagonal main surface 82b having eight faces corresponds to the (111) plane, and the quadrangular truncated top face 81b having six faces corresponds to the (100) plane.

  Here, the main surface means a surface having a mirror index having the largest total area of the surfaces having the same mirror index in the hexahedron or octahedron. Further, the truncated top surface means a surface formed by cutting away the vertex of the polyhedron. In FIG. 4, as an example, in the MgO fine particles 16a, the ratio of the (100) plane to the total area of the particles is 50% or more and 98% or less. On the other hand, in the MgO fine particles 16b, the ratio is set to 30% to 50%.

  The MgO fine particle 16c shown in FIG. 4C is a 26-hedron in which the oblique surface 83 is formed by cutting the boundary between adjacent (111) faces in the MgO fine particle 16b. Thereby, in the MgO fine particle 16c, there are 12 facets, ie, a truncated top face 81c made up of six octagonal (100) faces, a main face 82c made up of eight faceted hexagonal (111) faces. It is a 26-hedron having an oblique surface 83 made of a quadrangular (110) surface.

  Further, the MgO fine particle 16d shown in FIG. 4D is a 26-hedron in which an oblique surface 83d is formed by cutting a boundary between adjacent (100) surfaces in 16a. Thereby, in the MgO fine particle 16d, there are 12 main surfaces 81d consisting of six octagonal (100) faces, a truncated face 82d consisting of eight (hexagonal) (111) faces, and twelve faces. This is a 26-hedron having an oblique surface 83d composed of a quadrangular (110) surface. Depending on the firing conditions, the area occupied by the (100) plane or the (110) plane may be enlarged, and at this time, the (100) plane or the (110) plane becomes the main plane. Here, the oblique plane 83 refers to a plane formed by cutting out a side that is a line connecting two vertices in a 26-hedron.

  FIG. 5 is a diagram showing variations of the MgO fine particles 16a to 16d.

  The MgO fine particles 16a may have a hexahedral structure, and at least one truncated surface may be formed. For example, when there is a single truncated surface as in the MgO fine particle 16a1 shown in FIG. 5A, or when there are two truncated surfaces as in the MgO fine particle 16a2 shown in FIG. 5B. It is. At this time, the truncated surface corresponds to the (111) plane, and the main surface corresponds to the (100) plane. In addition, having a hexahedron structure and further having at least one truncated surface is a polyhedron having seven or more surfaces, and at least one surface is a truncated surface. In other words.

  The MgO fine particles 16b have an octahedral structure, and at least one truncated top surface may be formed. For example, when there is one truncated surface as in the MgO fine particle 16b1 shown in FIG. 5C, or when two truncated surfaces exist as in the MgO fine particle 16b2 shown in FIG. 5D. It is. At this time, the truncated surface corresponds to the (100) plane, and the main surface corresponds to the (111) plane. In addition, having an octahedral structure and further having at least one truncated surface is a polyhedron having nine or more surfaces, and at least one surface is a truncated surface. In other words.

  The MgO fine particles 16c have an octahedral structure, and it is sufficient that at least one truncated top surface and at least one oblique surface are formed. For example, as in the case of the MgO fine particles 16c1 shown in FIG. 5 (e), there are six top surfaces and one oblique surface. At this time, the main surface corresponds to the (111) plane, the truncated surface corresponds to the (100) plane, and the oblique plane corresponds to the (110) plane. In addition, having an octahedral structure and further having at least one truncated top surface and at least one oblique surface being formed is a polyhedron having 10 or more surfaces, and at least one surface is a truncated surface, Moreover, it can be paraphrased that it has a structure in which at least one surface is an oblique surface.

  The MgO fine particles 16d have a hexahedral structure, and it is sufficient that at least one truncated top surface and at least one oblique surface are formed. For example, as in the case of MgO fine particles 16d1 shown in FIG. 5 (f), there are eight facets and one oblique surface. At this time, the main surface corresponds to the (100) surface, the truncated surface corresponds to the (111) surface, and the oblique surface corresponds to the (110) surface. In addition, having a hexahedron structure and further having at least one truncated surface and at least one oblique surface formed is a polyhedron having eight or more surfaces, and at least one surface is a truncated surface, In other words, it has a structure in which at least one surface is an oblique surface.

  Here, the area ratio of each crystal plane that the MgO fine particles 16a, 16b, 16c, and 16d can take in each crystal structure will be described. According to the study by the present inventors, the above effect is effectively obtained in the PDP. The following area ratios are desirable.

  The ratio of the area occupied by the (100) plane on the surface of the MgO fine particles 16a on the entire surface of the MgO fine particles 16a is preferably in the range of 50% to 98%.

  The ratio of the area occupied by the (100) plane on the surface of the MgO fine particles 16b on the entire surface of the MgO fine particles 16b is preferably in the range of 30% to 50%.

  The ratio of the area occupied by the (111) plane on the surface of the MgO fine particles 16c on the entire surface of the MgO fine particles 16c is preferably in the range of 10% to 80%.

  Similarly, the ratio of the area occupied by the (100) plane on the surface of the MgO fine particles 16c on the entire surface of the MgO fine particles 16c is preferably in the range of 5% to 50%.

  Furthermore, the ratio of the area occupied by the (110) plane on the surface of the MgO fine particles 16c on the entire surface of the MgO fine particles 16c is preferably in the range of 5% to 50%.

  The ratio of the area occupied by the (111) plane on the surface of the MgO fine particle 16d on the entire surface of the MgO fine particle 16d is preferably in the range of 10% to 40%.

  Similarly, the ratio of the area of the (100) plane on the surface of the MgO fine particle 16d to the entire surface of the MgO fine particle 16d is preferably in the range of 40% to 80%.

  Furthermore, the ratio of the area occupied by the (110) plane on the surface of the MgO fine particle 16d on the entire surface of the MgO fine particle 16d is preferably in the range of 10% to 40%.

  Next, the cathode luminescence characteristics of the MgO fine particles will be described.

  Cathode luminescence (CL) measurement of MgO fine particles 16c and 16d surrounded by MgO fine particles produced by the conventional vapor phase oxidation method and specific three orientation planes of (100) plane, (110) plane and (111) plane The results are shown in FIG. As shown in FIG. 6, light emission in the vicinity of 200 to 300 nm is hardly detected in the CL spectrum of the MgO fine particles obtained by the vapor phase oxidation method. On the other hand, in the CL spectrum of the MgO fine particles 16c and 16d surrounded by the specific three kinds of orientation planes, the presence of a large peak can be confirmed in the vicinity. This light having a wavelength in the vicinity of 200 to 300 nm is also generated when the PDP is discharged.

  Furthermore, the energy of light having a wavelength of about 200 to 300 nm generated at the time of discharge is about 5 eV, and the MgO electrons existing within 5 eV from the vacuum level at the energy level are excited and emitted into the discharge space as secondary electrons. can do.

  As described above, if light having a wavelength of about 200 to 300 nm exists in the discharge cell at the time of discharge, the assist of electron emission by the space charge existing in the discharge cell becomes unnecessary. Here, in the PDP using the protective layer in which the MgO crystal dispersed by the vapor phase oxidation method is dispersed, the discharge delay varies depending on the number of discharge pulses. However, there is light having a wavelength of about 200 to 300 nm. In this case, since the dependence on the space charge is eliminated, the phenomenon in which the current discharge delay changes is eliminated.

  As described above, in the PDP in which the MgO fine particles 16c and 16d surrounded by the specific three kinds of orientation surfaces in which the deep ultraviolet light (DUV) is detected by the CL measurement are disposed, light having a wavelength in the vicinity of 200 to 300 nm is thereby discharged during the discharge. It is thought to occur. Therefore, it is expected that a PDP having no space charge dependency can be realized by using the MgO fine particles 16c and 16d surrounded by the specific three kinds of orientation planes.

  Further, ultraviolet light emission generated when the MgO fine particles produced by the precursor firing method were excited by vacuum ultraviolet light having a wavelength of 173 nm was actually measured and confirmed. FIG. 7 shows the light emission spectrum actually measured.

  As shown in FIG. 7, in the wavelength range of 200 nm to 300 nm, there is a waveform having a maximum peak emission intensity, and ultraviolet rays generated from MgO fine particles can be confirmed. It has been found that even when excited by vacuum ultraviolet light having a wavelength of 147 nm, similar ultraviolet light emission can be obtained.

  By arranging the MgO fine particles 16a to 16d having such properties in the phosphor layer, the MgO fine particle group 16 is excited by vacuum ultraviolet light having a wavelength of 147 nm or 173 nm generated from the Xe gas in the PDP panel. Emits ultraviolet light of 200 to 300 nm. Thereby, the phosphor material constituting the phosphor layer is excited, and the luminance is improved.

  Further, the MgO fine particles of the present invention were prepared by firing the MgO precursor in a temperature range of 700 ° C. or higher and lower than 2000 ° C., and the frequency of the BET value was measured. FIG. 8 shows the measurement results.

The specific surface area (BET value) was measured based on the BET method by adsorbing gas molecules (N ₂ ) whose adsorption occupation area was known on the surface of the MgO fine particles and determining the adsorption amount.

As shown in FIG. 8, the BET value of the MgO fine particles of the present invention varies slightly depending on the conditions such as the kind of MgO precursor, the firing profile, and the firing atmosphere, but is generally 1.0 m ² / g or less, 2.0 m. It falls within the range of ² / g, and most of it is concentrated in the range of 1.0 m ² / g to 1.6 m ² / g. On the other hand, MgO fine particles produced by the vapor phase oxidation method have a BET value of about 7.0 m ² / g.

  As described above, the MgO fine particles produced by the precursor firing method have a property that the specific surface area is smaller than that of the MgO fine particles produced by the vapor phase oxidation method. Since the area in contact with the unnecessary gas in the inside is reduced as compared with the conventional case, the amount of gas adsorption is suppressed, and it is considered that excellent adsorption resistance is exhibited over time.

  As described above, by arranging the MgO fine particles 16a to 16d having excellent secondary electron emission characteristics in the phosphor layer 14, ultraviolet light having a wavelength of 147 nm or 173 nm generated in the discharge space 15 is driven during the driving. , MgO fine particles 16a to 16d filled in the gaps between the phosphor particles receive the ultraviolet rays and exhibit secondary electron emission characteristics. Here, as described above, the MgO fine particles 16 a to 16 d are much more excellent in secondary electron emission characteristics than the conventional fine particles, and have a characteristic of emitting abundant secondary electrons toward the discharge space 15. Therefore, by utilizing this characteristic, when a voltage having a ramp waveform (FIG. 3) is applied between the scan electrode 4 and the data electrode 11 during the initialization period, the voltage is emitted from the phosphor layer 14 toward the discharge space 15. Abundant secondary electrons cause an ideal weak discharge to occur smoothly. For this reason, it is possible to suppress the occurrence of an unfavorable strong discharge (initialized bright spot) that can be confirmed with the naked eye, and to smoothly advance the weak discharge, effectively eliminating the problem of image display performance degradation due to the initialized bright spot. Can be prevented.

  In addition, when the size of the MgO fine particles is small or the ratio of the total fine particles to the surface area is small, the above discharge characteristics corresponding to each surface may not be sufficiently exhibited. As will be described later, the MgO fine particles produced by the vapor phase oxidation method have a relatively varied particle size, and the fine particles having a particle size of less than 300 nm are formed in the (100) plane even though the discharge is performed. The problem of temperature dependence of the delay may occur. However, the MgO fine particles 16a to 16d produced by the precursor firing method have a uniform particle size, and almost all the fine particles have a particle size of 300 nm or more. Thereby, almost all of the fine particles can exhibit discharge characteristics corresponding to each orientation plane.

  In addition, since the (110) plane exhibits excellent electron emission characteristics in a wide temperature range from low temperature to high temperature, the (110) plane is surrounded by the (110) plane in addition to the (100) plane and the (111) plane. By utilizing the MgO fine particles 16c and 16d, an abundant secondary electron emission effect from the phosphor layer 14 can be expected.

  Furthermore, the MgO fine particles 16a to 16d are mixed in the phosphor layer 14, whereby the visible light emission efficiency of the phosphor particles can be improved satisfactorily. That is, when vacuum ultraviolet light having a wavelength of 147 nm or 173 nm generated in the discharge space 15 reaches the MgO fine particles 16a to 16d in the phosphor layer, the MgO fine particles 16a to 16d are excited and emit the secondary electrons described above. , Itself generates ultraviolet rays in a wavelength range of about 200 nm to 300 nm. Since the phosphor component receives both the vacuum ultraviolet light from the discharge space 15 and the ultraviolet light from the MgO fine particles 16a to 16d, the visible light conversion process is actively performed. In particular, in the phosphor layer 14, the presence of the MgO fine particles 16a to 16d so as to surround the periphery of the phosphor particles can be expected to effectively excite the phosphor particles from the periphery. As a result, light emission with high luminance is exhibited due to excellent visible light emission efficiency. In addition, ultraviolet rays having a wavelength range of about 200 nm to 300 nm have better energy conversion efficiency in MgO than that of vacuum ultraviolet light having a wavelength of 147 nm or 173 nm, and promote active secondary electron emission. Such ultraviolet excitation action of the phosphor particles by the MgO fine particles 16a to 16d can be obtained particularly effectively in the MgO fine particles 16a to 16d of the present invention having specific CL characteristics.

  Further, since the MgO fine particles 16a to 16d have sufficiently high secondary electron emission characteristics as compared with the phosphor components, there is a relative variation in discharge characteristics due to the phosphor components in the phosphor layers 14 of the respective colors. Disappears. As a result, it becomes possible to make the discharge characteristics uniform in the discharge cells of the entire PDP, and stable image display performance is exhibited.

  As described above, according to the PDP of the present invention, by arranging the MgO fine particles 16a to 16d having excellent secondary electron emission characteristics in the phosphor layer 14, it is preferable that the 2 from the phosphor layer to the discharge space 15 is excellent during driving. Secondary electron emission can be performed. As a result, a weak discharge can be generated smoothly during the initialization period, and the generation of initialization bright spots can be improved. Further, since the MgO fine particles 16a to 16d have sufficiently high secondary electron emission characteristics as compared with the phosphor components, variations in discharge characteristics due to the respective phosphor components in the respective color phosphor layers 14 are relatively conspicuous. Disappear. As a result, it becomes possible to make the discharge characteristics uniform in the discharge cells of the entire PDP, and stable image display performance can be expected.

  Next, another embodiment of the present invention will be described. FIG. 9 is a cross-sectional view showing a PDP according to another embodiment.

  In the PDP according to the present embodiment, the protective film 8 on the front panel 2 has the same crystal structure as the base film 81 formed on the dielectric layer 7 and the MgO fine particle group 16 disposed on the base film 81. The MgO fine particle group 82 is composed of the MgO fine particle group 82, and the MgO fine particle group 82 having the same crystal structure as the MgO fine particle group 16 is disposed in the surface region facing the discharge space 15. Similar to the MgO fine particle group 16, the MgO fine particle group 82 includes MgO fine particles 16a to 16d.

  According to the PDP having such a configuration, the arrangement of the MgO fine particle group 82 can be expected to further suppress the initialization bright spot and improve the luminance of the entire PDP.

  That is, in the conventional PDP, vacuum ultraviolet light having a wavelength of 147 nm or 173 nm generated as a spherical wave by the discharge gas in the discharge space substantially does not contribute to visible light emission in the protective layer made of MgO on the front panel 2 side. , Absorbed by the protective layer. Therefore, only a part of the ultraviolet rays that reach the phosphor layer out of the spherical ultraviolet rays are used for the visible light emission of the phosphor, and the remaining ultraviolet rays irradiated on the front panel side are almost contributed to the visible light emission. It can be said that it has been wasted.

  On the other hand, in the PDP according to the present embodiment, in addition to the MgO fine particle group 16 in the phosphor layer 14 arranged on the back panel 9 side, the MgO fine particle group 82 on the protective film 8 arranged on the front panel 2 side. However, it is irradiated without waste by ultraviolet light emission having a wavelength of 147 nm or 173 nm generated as a spherical wave. For this reason, the MgO fine particles 16a to 16d in the phosphor layer 14 are directly excited by ultraviolet light having a spherical wave wavelength of 147 nm or 173 nm, and in addition to the back panel 9 side and the front excited by the ultraviolet light of the spherical wave. Since it is possible to receive ultraviolet light having a wavelength of 200 to 300 nm, which is a relatively long wavelength, from the MgO fine particles on the panel 2 side, excitation is efficiently performed. As a result, the phosphor particles in the phosphor layer 14 emit abundant visible light using the entire surface.

  Further, the MgO fine particles 16 a to 16 d arranged on both the front panel 2 and the back panel 9 both receive ultraviolet light generated as spherical waves, thereby releasing a large amount of secondary electrons into the discharge space 15. Thereby, in the discharge space 15, a discharge of a favorable scale is formed using the secondary electrons.

  The 200 to 300 nm ultraviolet light emitted from the MgO fine particles 16a to 16d has a longer life than the ultraviolet light generated from the 147 nm or 173 nm vacuum ultraviolet light generated from the Xe gas in the discharge gas. For this reason, by continuously irradiating the ultraviolet rays generated from the MgO fine particles 16a to 16d, electrons in the phosphor layer 14 continue to exist in a relatively shallow level, and the electron emission characteristics of the phosphor are improved. An effect is obtained.

  Further, as a further feature of the PDP according to the present embodiment, there is an advantage that improvement can be expected for the problem of the discharge delay and the temperature dependency of the discharge delay and the space charge dependency of the discharge delay according to the following principle.

  That is, an MgO crystal having a cubic lattice NaCl crystal structure generally has a (111) plane, a (110) plane, and a (100) plane as main orientation planes.

  Of these, the (100) plane is the most dense surface (a surface in which atoms are densely packed) among these three orientation planes, and has the lowest surface free energy, so at low temperatures and at high temperatures above room temperature. It is difficult to adsorb impurity gases (water, hydrocarbons, carbon dioxide, etc.) in a wide temperature range, and unnecessary chemical reactions are unlikely to occur. Therefore, according to the characteristics of the (100) plane, good chemical stability can be expected even in a low temperature range where the influence of impurity gas adsorption is particularly large (for example, surface technology Vol. 41. No. 4 1990, page 50). ). Therefore, if MgO having a (100) plane is applied to the PDP, it is possible to prevent the impurity gas (especially hydrocarbon gas) inside the discharge space 15 from being adsorbed over a wide temperature range at a low temperature and a high temperature at room temperature or higher. The temperature dependence of the discharge delay can be eliminated (J. Chem. Phys. Vol. 103. No. 8 3240-3252 1995). However, the (100) plane has a small amount of electron emission in a wide temperature range at a low temperature and at a high temperature above room temperature. Therefore, if the orientation plane depends only on the (100) plane, a discharge delay occurs, and this problem can occur more remarkably due to the reduction of the address discharge period accompanying the high definition of the PDP.

  On the other hand, the (111) plane is a crystal plane that exhibits good electron emission characteristics at room temperature or higher, and an effect of preventing discharge delay at room temperature or higher can be expected. However, the surface energy is the highest among the above three crystal planes, but there is a drawback that impurity gas (especially hydrocarbon gas) in the discharge space 15 is likely to be adsorbed to MgO below room temperature. When the adsorbed impurity gas aggregates on the surface of the crystal plane, electron emission is hindered. Therefore, even if the orientation plane depends only on the (111) plane, another problem of temperature dependence of discharge delay (particularly, discharge delay in a low temperature region) occurs.

  The (110) plane is an orientation plane having a large electron emission characteristic in a wide temperature range from a low temperature to a high temperature as described above.

  Therefore, in the present embodiment, MgO fine particles 16a and 16b having a NaCl crystal structure surrounded by a specific two-orientation plane composed of a (100) plane and a (111) plane are formed on the MgO fine particle group 82 on the protective film 8. Further, MgO fine particles 16c and 16d having a NaCl crystal structure surrounded by a specific three-orientation plane composed of (100) plane, (110) plane, and (111) plane are mixed and used.

  Therefore, at the time of driving, firstly, depending on the characteristics of the (100) plane and (111) plane, at low temperature (when the PDP is driven or used in an area where the environmental temperature is low) and at high temperature above room temperature (after a certain period of time has elapsed since driving started In the wide temperature range (when used in areas with high environmental temperatures), stable electron emission characteristics are maintained by preventing the adsorption of impurity gases, which makes “discharge delay” and “temperature dependence of discharge delay”. Each problem is effectively suppressed.

  Furthermore, due to the unique characteristics of the MgO fine particles 16c and 16d having the (110) plane, sufficient electron emission characteristics can be obtained without the assistance of space charge generated at the start of discharge in the early stage of PDP driving, and display during the sustain discharge period. There is an advantage that stable electron emission is possible regardless of the number of pulses (number of sustain pulses) applied to the electrode pair 6.

  As described above, in the PDP according to the present embodiment, in addition to “discharge delay” and “temperature dependency of discharge delay”, “space charge dependency of discharge delay” can be suppressed, and better image display performance can be exhibited. It can be expected.

  Here, a method for manufacturing a PDP according to the present invention will be described.

(Method for producing MgO fine particles)
In order to obtain the MgO fine particles 16a to 16d, for example, a high-purity magnesium compound (MgO precursor) is uniformly heat-treated and fired in a high-temperature oxygen-containing atmosphere (700 ° C. or higher).

  Examples of magnesium compounds that can be used for the MgO precursor include magnesium hydroxide, magnesium alkoxide, magnesium acetylacetone, magnesium nitrate, magnesium chloride, magnesium carbonate, magnesium sulfate, magnesium oxalate, and magnesium acetate. In the present invention, any one or more of these (a mixture of two or more may be used) can be selected. Depending on the selected compound, it may usually take the form of a hydrate, but such a hydrate may be used.

  Furthermore, the purity of the magnesium compound used as the MgO precursor is preferably 99.95% or more, and more preferably 99.98% or more. This is because when a large amount of impurity elements such as alkali metal, boron, silicon, iron, and aluminum are present in the magnesium compound, fusion and sintering between particles occur during heat treatment (especially when the firing temperature is high), resulting in crystallinity. This is because the high MgO fine particles are difficult to grow, whereas the problem can be prevented by using a high-purity magnesium compound.

  When such a high-purity MgO precursor is fired in an oxygen-containing atmosphere, the purity of the MgO fine particles 16a to 16d to be produced also becomes 99.95% or higher, or 99.98% or higher.

  Next, when setting a calcination temperature, 700 degreeC or more is preferable and 1000 degreeC or more is still more preferable. This is because when the firing temperature is lower than 700 ° C., the crystal plane does not develop sufficiently, the number of defects increases, and the adsorption of impurity gas to the fine particles increases. However, when the firing temperature reaches a temperature higher than 2000 ° C., oxygen escape occurs, resulting in an increase in MgO defects and adsorption. For this reason, 1800 degrees C or less is preferable.

  Here, when baking is performed under a baking temperature condition of 700 ° C. or more and 2000 ° C. or less, MgO fine particles 16a to 16d surrounded by specific two kinds and three kinds of orientation surfaces are generated together. According to another experiment by the present inventor, it has been found that when firing is performed at a temperature of about 1500 ° C. or higher, the (110) plane tends to shrink. Therefore, a firing temperature of 700 ° C. or more and less than 1500 ° C. is preferable in order to increase the generation frequency of the MgO fine particles 16c and 16d surrounded by the specific three kinds of orientation planes. On the other hand, a firing temperature of 1500 ° C. or more and 2000 ° C. or less is preferable in order to increase the generation frequency of the MgO fine particles 16a and 16b surrounded by the specific two kinds of orientation surfaces.

  In addition, each MgO fine particle 16a-16d can also be isolate | separated from each other through a selection process.

  Here, the process of producing magnesium hydroxide as an MgO precursor by a liquid phase method and the process of producing powder containing MgO fine particles 16a to 16d using the magnesium hydroxide will be specifically described.

(1) Prepare magnesium alkoxide (Mg (OR) ₂ ) or magnesium acetylacetone having a purity of 99.95% or more as a starting material. By adding a small amount of acid to an aqueous solution in which these are dissolved and hydrolyzing, a magnesium hydroxide gel as an MgO precursor is prepared. And the powder containing MgO microparticles | fine-particles 16a-16d is produced by baking and dehydrating the said gel at 700 to 2000 degreeC in the air.

(2) Magnesium nitrate (Mg (NO ₃ ) ₂ ) having a purity of 99.95% or more is used as a starting material, and an aqueous solution in which this is dissolved is prepared. Then, an alkaline solution is added to this aqueous solution to produce a magnesium hydroxide precipitate. Next, the magnesium hydroxide precipitate is separated from the aqueous solution, and calcined at 700 ° C. or higher and 2000 ° C. or lower in the air for dehydration, whereby powder containing MgO fine particles 16a to 16d is produced.

(3) Prepare an aqueous solution in which magnesium chloride (MgCl ₂ ) having a purity of 99.95% or more is used as a starting material. Then, calcium hydroxide (Ca (OH) ₂ ) is added to the aqueous solution to precipitate magnesium hydroxide (Mg (OH) ₂ ) as an MgO precursor. The precipitate is separated from the aqueous solution, and calcined at 700 ° C. or more and 2000 ° C. or less in the air for dehydration, whereby powder containing MgO fine particles 16a to 16d is produced.

In each of the liquid phase methods (1) to (3) described above, an acid (Mg (OR) ₂ ), (Mg (NO ₃ ) ₂ ) or magnesium chloride (MgCl ₂ ) solution having a purity of 99.95% or more is added to an acid solution. By adding and hydrolyzing while controlling the concentration, a very fine precipitate of magnesium hydroxide (Mg (OH) ₂ ) can be formed. By baking this precipitate in air at 700 ° C. or higher, H ₂ O (water) is desorbed from Mg (OH) ₂ and MgO powder is formed. Since the powder containing the MgO fine particles 16a to 16d produced by this method has few crystallographic defects, the hydrocarbon gas is hardly absorbed.

  Here, the MgO fine particles generally produced by the vapor phase oxidation method have a relatively varied particle size.

  For this reason, in the conventional manufacturing process, in order to obtain uniform discharge characteristics, a classification process for selecting particles having a certain particle size range is required (for example, described in JP-A-2006-147417).

  On the other hand, in the present invention, MgO precursors are calcined to obtain MgO fine particles, but the MgO fine particles have a more uniform particle size than the conventional one and fall within a certain particle size range. Specifically, the size of the MgO fine particles produced in the present invention is in the range of 300 nm to 2 μm. For this reason, particles having a specific surface area smaller than that of a crystal produced by a gas phase oxidation method can be obtained. This is one factor that the MgO fine particles 16a to 16d of the present invention are excellent in adsorption resistance, and is considered to improve the electron emission performance. Further, according to the present invention, it is possible to omit the classification step of distributing unnecessary fine particles, and there is a very advantageous aspect in terms of manufacturing efficiency and cost due to the simplification of the process.

Note that Mg (OH) ₂ that is an MgO precursor is a hexagonal compound and is different from a cubic octahedral structure that MgO can take. Therefore, the crystal growth process in which Mg (OH) ₂ is thermally decomposed to produce MgO crystals is complicated, but MgO is formed while leaving the hexagonal Mg (OH) ₂ form, so that the crystal plane (100) plane and (111) plane, and in addition to these, (110) plane is considered to be formed.

  On the other hand, when forming MgO by the vapor phase synthesis method, only a specific surface is likely to grow. For example, in a method in which a small amount of oxygen gas is flowed while heating Mg (magnesium metal) to a high temperature in a tank filled with an inert gas to directly oxidize Mg to form MgO powder, the crystal growth process Thus, while Mg takes in oxygen, only the (100) plane appears on the surface, and other orientation planes are difficult to grow.

As other MgO fine particle production methods, as with the method of calcining magnesium hydroxide, MgO precursors include NaCl types such as magnesium alkoxide, magnesium nitrate, magnesium chloride, magnesium carbonate, magnesium sulfate, magnesium oxalate, and magnesium acetate. Using a magnesium compound that is not (cubic), a step of thermal decomposition in a thermal equilibrium state directly at a high temperature of 700 ° C. or higher may be performed. According to these steps, when (OR) ₂ group, Cl ₂ group, (NO ₃ ) ₂ group, CO ₃ group, C ₂ O ₄ group and the like coordinated to Mg element are eliminated, The powder containing MgO fine particles 16a to 16d surrounded by the specific two-orientation plane or the specific three-orientation plane is obtained by a mechanism in which not only the (100) plane but also the (110) plane and the (111) plane appear on the surface. can get.

(Preparation of front panel)
A display electrode is produced on a glass substrate made of soda-lime glass having a thickness of about 2.6 mm. Here, an example in which the display electrode pair 6 is formed by a printing method is shown, but other than this, it can be formed by a die coating method, a blade coating method, or the like.

First, a transparent electrode material such as ITO, SnO ₂ , or ZnO is applied on a glass substrate in a predetermined pattern such as a stripe with a final thickness of about 100 nm and dried. Thereby, a transparent electrode is produced.

  On the other hand, a photosensitive paste obtained by mixing a photosensitive resin (photodegradable resin) with Ag powder and an organic vehicle was prepared, and this was applied on the transparent electrode so as to match the pattern of the bus line to be formed. Cover with a mask with openings. And it exposes from the said mask, a baking process is carried out at the baking temperature of about 590-600 degreeC through a development process. As a result, a bus line having a final thickness of several μm is formed on the transparent electrode. According to this photomask method, the bus line can be thinned to a line width of about 30 μm as compared with the screen printing method in which the line width of 100 μm is conventionally limited. As the metal material for the bus line, in addition to Ag, Pt, Au, Al, Ni, Cr, tin oxide, indium oxide, or the like can be used. In addition to the above method, the bus line can also be formed by performing an etching process after forming an electrode material by vapor deposition or sputtering.

Next, a paste in which an organic binder composed of lead-based or non-lead-based low-melting glass having a softening point of 550 ° C. to 600 ° C., SiO ₂ material powder, butyl carbitol acetate, etc. is mixed from above the display electrode pair 6. Apply. Then, baking is performed at about 550 ° C. to 650 ° C. to form the dielectric layer 7 having a final thickness of several μm to several tens of μm.

  Here, when manufacturing the PDPs 1 and 1a, a protective film having a predetermined thickness is formed on the surface of the dielectric layer. A sputtering method was used as the film forming method. The target material was irradiated with Ar ions using Ar as an operating gas in an RF sputtering apparatus. The substrate temperature at the time of film formation, the operating gas partial pressure amount and the like do not have a great influence on the composition of the protective film after film formation, and may be arbitrarily set.

  The method for forming the protective film is not limited to the above sputtering method, and other thin film methods such as an EB method, an ion plating method, and a CVD method may be used.

  Further, when the PDP shown in FIG. 9 is manufactured, MgO fine particle groups are formed on the surface of the dielectric layer or the base film. When a solvent containing MgO fine particles is applied by a screen printing method, a spray method or the like, and then the solvent is removed and sufficiently dried, MgO fine particle groups can be formed.

  Thus, the front panel 2 is manufactured.

(Production of back panel)
On a surface of a glass substrate made of soda lime glass having a thickness of about 2.6 mm, a conductive material mainly composed of Ag is applied in a stripe pattern at a predetermined interval by screen printing, and the thickness is several μm (for example, about 5 μm). ) Data electrode. As electrode materials for data electrodes, metals such as Ag, Al, Ni, Pt, Cr, Cu, Pd, conductive ceramics such as carbides and nitrides of various metals, combinations thereof, or a laminate thereof A laminated electrode formed as described above can be used as necessary.

Subsequently, a glass paste made of lead-based or non-lead-based low-melting glass or SiO ₂ material is applied at a thickness of about 20 to 30 μm over the entire surface of the glass substrate on which the data electrodes are formed, and a dielectric layer is formed. To do.

  Next, partition walls are formed in a predetermined pattern on the dielectric layer surface. The barrier ribs are formed by applying a low melting point glass material paste and using a sandblasting method or a photolithography method to form a plurality of arrays of discharge cells so as to partition the periphery of the boundary with adjacent discharge cells. Form with a pattern.

  Once the barrier ribs have been formed, the phosphor is either red (R) phosphor, green (G) phosphor or blue (B) phosphor on the wall surface of the barrier rib and the surface of the dielectric layer exposed between the barrier ribs. Create a layer.

  At this time, a dispersion obtained by dispersing MgO fine particles in a solvent is applied to the surface of the dielectric layer and dried to form MgO fine particle groups.

  Moreover, the following composition can be utilized for each color phosphor of RGB.

Red phosphor; Y ₂ O ₃ ; Eu ³⁺
Green phosphor; Zn ₂ SiO ₄ : Mn
Blue phosphor; BaMgAl ₁₀ O ₁₇ : Eu ²⁺
As a method for forming the phosphor layer, any known method such as an electrostatic coating method, a spray method, or a screen printing method can be employed.

Among these, when using the electrostatic coating method, ethyl cellulose and α-terpineol are used as a solvent and a solvent, respectively, and phosphor powder and powder having an average particle size of 2.0 μm are added thereto and mixed by a sand mill. Thus, a phosphor ink having a viscosity of about 15 × 10 ⁻³ Pa · s is produced. This phosphor ink is put into a server, sprayed from a nozzle having a diameter of 60 μm by a pump, and applied between adjacent partitions. At this time, the panel is moved in the longitudinal direction of the partition wall, and the phosphor ink is applied in a stripe shape. After the application, the phosphor ink is baked at 500 ° C. for 10 minutes to remove the solvent / solvent. Thereby, a phosphor layer in which the MgO fine particle group is dispersed in the layer is formed.

  Further, when MgO fine particles are arranged on the surface of the phosphor layer, a dispersion liquid in which MgO fine particles are dispersed in a solvent is prepared, and this is dispersed by an electrostatic coating method, a spray method, a screen printing method, or the like. Then, it can be formed by drying and fixing.

(PDP panel assembly)
The produced front panel and back panel are bonded together using sealing glass. Thereafter, the inside of the discharge space is evacuated to a high vacuum (1.0 × 10 ⁻⁴ Pa) to remove air and impurity gases. And Xe mixed gas, such as Ne-Xe type | system | group, He-Ne-Xe type | system | group, Ne-Xe-Ar type | system | group, is enclosed as discharge gas with the predetermined | prescribed pressure (here 20 kPa-101 kPa). The Xe concentration in the mixed gas is 15% to 100%.

  In addition, as long as Xe gas is enclosed as discharge gas, you may comprise not only the above but a mixed system with other noble gases.

  The PDP is completed through the above steps.

  Next, an example of the present invention was prepared together with a comparative example, and a performance evaluation test of the present invention was performed. The results are shown below.

(Experiment 1)
Relationship between weight concentration of MgO fine particles and luminance change by driving PDP arranged as phosphor layer by changing the amount of MgO fine particles produced by vapor phase oxidation method and precursor firing method in combination with phosphor components Investigated about. As the phosphor, a blue phosphor BaMgAl ₁₀ O ₁₇ : Eu having general fluorescence characteristics was used. As the MgO fine particles, MgO fine particles 1 and 2 prepared by firing a precursor and MgO fine particles 3 of a comparative example prepared by a vapor phase oxidation method were prepared. Each BET value of a prepared MgO particles 1-3 was 1.0m ² /g,2.0m ² /g,7.1m ² / g in the same order.

  The result of the experiment is shown in FIG. As shown in FIG. 10, it can be confirmed that the brightness of the MgO fine particles 3 rapidly decreases as the mixing amount increases, and the brightness decreases to about 80% when the weight concentration in the entire phosphor layer reaches 10 wt%. This is presumably because the visible light emitted from the phosphor is shielded or diffusely reflected by the MgO fine particles, and as a result, it cannot be extracted well from the front panel side and the luminance is reduced.

  In addition, the MgO fine particles 3 produced by the vapor phase oxidation method have a relatively large variation in particle size, and microscopically there are many fine particles having a small particle size around crystal particles having a large particle size. Therefore, the BET value is large. When such MgO fine particles are used, unnecessary visible light scattering occurs, which may adversely affect image display performance.

In contrast, in the MgO particles 1 and 2, BET value is adjusted lower to 1.0m ² /g,2.0m ² / g, respectively, even if the weight concentration in the entire phosphor layer reaches about 10 wt%, Luminance deterioration was not so much compared with the MgO fine particles 3. This is because, in the MgO fine particles 1 and 2, visible light emitted in a spherical shape from the phosphor is well reflected by the MgO fine particles having a small BET value present in the voids of the phosphor layer, and irregular reflection is also prevented at that time. Therefore, it is considered that the factor of luminance reduction is compensated as compared with the MgO fine particles 3. It has been found that the effect of reflecting visible light is greater as the BET value is smaller, and that the irregular reflection of visible light from the phosphor is also suppressed as the BET value is smaller.

Further, in the case of the MgO fine particles 1 having a BET value of 1.0 m ² / g, the luminance increases with the weight concentration of the MgO fine particles, and the luminance becomes maximum at about 5 wt% in the graph. Therefore, it is considered that the actual maximum luminance value is within the range of 5 wt% or more and 10 wt% or less. As described above, the MgO fine particles 1 and 2 are less likely to decrease in luminance even when the weight concentration of the MgO fine particles is increased. However, this is excited by ultraviolet rays having a wavelength of 147 nm or 173 nm that the fine particles receive from the discharge space, and the fine particles themselves have a wavelength of 200 to 200. Since the phosphor emits 300 nm ultraviolet light, the phosphor particles surrounded by the phosphor emit well visible light, and it is considered that the effect of further improving luminance is obtained.

  The MgO fine particles (MgO fine particles 3) produced by the vapor phase oxidation method have a smaller secondary electron emission than the MgO fine particles (MgO fine particles 1 and 2) produced by the precursor firing method. As a result, in order to effectively prevent the occurrence of initialization bright spots and obtain a desired effect, the phosphor layer must be disposed in a larger amount than the MgO fine particles produced by the precursor firing method. However, in the MgO fine particles produced by the vapor phase oxidation method, as shown in the graph, there is a problem that the luminance decreases as the weight concentration of the MgO fine particles increases. Therefore, it is desirable to use MgO fine particles produced by a precursor firing method as in the present invention in order to prevent the occurrence of initialization bright spots and simultaneously achieve improvement in luminance.

(Experiment 2)
Next, PDPs of Samples 1 to 8 of Examples and Comparative Examples were prepared, and the occurrence rate and luminance of the initialization bright spot were examined. Samples 2 to 4 (Examples 1 to 3) are prepared in accordance with the PDP of the first embodiment shown in FIG. 1, and samples 6 to 8 (Examples 4 to 6) are the PDP of the second embodiment shown in FIG. It produced according to the structure of.

  The occurrence rate of the initialization bright spot was measured by decomposing it into RGB by image processing and calculating the emission area per unit area. First, an initialization bright spot is generated in the PDP of each sample, captured as an image on a PC, and decomposed into RGB. Then, the threshold value of the emission intensity is determined in the image decomposed into RGB, the presence / absence of the emission is determined by whether or not the threshold value is exceeded, and the occurrence rate of the initialization bright spot is determined by the area of the portion emitting light per unit area Was calculated.

  The luminance was measured by driving the PDP of each sample at a discharge sustaining voltage of 180 V and a frequency of 200 kHz and using a luminance meter.

  Each sample was adjusted as follows.

  Sample 1 (Comparative Example 1): As the most basic configuration of the PDP, a structure in which MgO fine particles are not disposed on the phosphor on the back panel side and the dielectric layer on the front panel side is used.

  Sample 2 (Example 1): The phosphor layer on the back panel side has MgO fine particles prepared by firing the precursor at a ratio of 0.5 wt%, and the dielectric layer on the front panel side has MgO fine particles. It was set as the structure which does not arrange | position.

  Sample 3 (Example 2): The phosphor layer on the back panel side is provided with MgO fine particles prepared by firing the precursor at a rate of 2 wt%, and the dielectric layer on the front panel side is provided with MgO fine particles. The structure is not provided.

  Sample 4 (Example 3): The phosphor layer on the back panel side is provided with MgO fine particles prepared by firing the precursor at a rate of 10 wt%, and the MgO fine particles are provided on the dielectric layer on the front panel side. The structure is not provided.

  Sample 5 (Comparative Example 2): MgO fine particles are not arranged on the phosphor layer on the back panel side, and magnesium oxide fine particles produced by firing the precursor are arranged on the dielectric layer on the front panel side. It was.

  Sample 6 (Example 4): MgO fine particles prepared by firing the precursor at a ratio of 0.5 wt% are disposed in the phosphor layer on the back panel side, and the precursor is disposed on the dielectric layer on the front panel side. The structure is such that magnesium oxide fine particles produced by body firing are not disposed.

  Sample 7 (Example 5): The phosphor layer on the back panel side is provided with MgO fine particles prepared by firing the precursor at a rate of 2 wt%, and the precursor layer is fired on the dielectric layer on the front panel side. The magnesium oxide fine particles produced by the above were not disposed.

  Sample 8 (Example 6): MgO fine particles prepared by firing the precursor at a rate of 10 wt% are disposed in the phosphor layer on the back panel side, and precursor firing is performed on the dielectric layer on the front panel side. The magnesium oxide fine particles produced by the above were not disposed.

  FIG. 11 shows a graph of the frequency of occurrence of initializing bright spots and FIG. 12 shows a graph of luminance for the results of the experiment of each sample PDP performed under the above conditions.

  From the results shown in FIG. 11, in the samples 2, 3, and 4 (Examples 1, 2, and 3) corresponding to the first embodiment, the frequency of occurrence of the initialization bright spot is higher than that of the sample 1 (Comparative Example 1). It was confirmed that the PDP had particularly excellent performance as a PDP. This is considered to be because the secondary electron emission coefficient γ in the entire phosphor layer can be dramatically increased as compared with the conventional case by combining the phosphor component and the MgO fine particles produced by the precursor firing method. Further, it was found that the frequency of occurrence of the initialization bright spot is remarkably reduced as the weight concentration of the MgO fine particles in the phosphor layer is increased.

  On the other hand, from the results shown in FIG. 12, the samples 2, 3, and 4 (Examples 1, 2, and 3) corresponding to the configuration of the first embodiment have higher luminance than the sample 1 (Comparative Example 1). Thus, it can be confirmed that particularly excellent image display performance is exhibited as a PDP. In the experimental results, the highest luminance was obtained when the weight concentration of the MgO fine particles in the phosphor layer was 2 wt%.

  In addition, in Samples 6, 7, and 8 (Examples 4, 5, and 6) corresponding to the second embodiment, the frequency of occurrence of the initialization bright spot is reduced compared to Sample 5 (Comparative Example 2). It was confirmed that it had good characteristics. Samples 6, 7, and 8 (Examples 4, 5, and 6) are compared with Samples 2, 3, and 4 (Examples 1, 2, and 3) in terms of improvement of the initialization bright spot and improvement in luminance. It was confirmed that the film had better performance.

  As described above, in each example, unlike the comparative example, MgO fine particles formed by the precursor firing method are mixed with the phosphor component. For this reason, since the phosphor is excited by ultraviolet rays by the MgO fine particles in addition to the ultraviolet rays generated in the discharge gas, visible light emission can be efficiently generated, and emission with high luminance is possible. . In each embodiment, the visible light emission once generated by the phosphor is well reflected by the MgO fine particles to the front panel side and used for image display. It seems to be a factor that

  In addition, when the weight concentration of the MgO fine particles in the phosphor layer increases, the light shielding effect of visible light generated in the phosphor particles by the MgO fine particles increases. Therefore, when adding MgO fine particles to the phosphor layer, it is not intended to improve the luminance by simply setting a large weight concentration, but the maximum luminance can be obtained with the assumption of a visible light shielding effect. In addition, it should be adjusted according to the balance between these two effects.

  From the above experimental results, the superiority of the present invention was confirmed.

  In the PDP in each of the above embodiments, examples in which 16a to 16d are used as the MgO fine particles have been shown, but the present invention does not need to use all of these four types of MgO fine particles at the same time.

  In addition, the MgO fine particles in the present invention may be included so as to be substantially the main component in the MgO fine particle group, and may be configured to include some conventional MgO fine particles due to manufacturing errors or the like. .

  As described above, the present invention can drive a high-definition image display at a low voltage, but it can be used as a gas discharge panel technology in a television set in a transportation facility, public facility, home, etc., a display device for a computer, or the like. Is possible.

Sectional drawing which shows the structure of PDP which concerns on one embodiment of this invention Schematic diagram showing the relationship between each electrode and driver Waveform diagram showing an example of driving waveform of PDP Explanatory drawing showing the shape of MgO fine particles Explanatory drawing showing the shape of MgO fine particles Graph showing CL measurement waveform of MgO fine particles Graph showing the relationship between emission wavelength and emission intensity of MgO fine particles Graph showing relationship between BET value and frequency of MgO fine particles Sectional drawing which shows the structure of PDP which concerns on other embodiment of this invention. Graph showing the relationship between luminance and MgO weight concentration in the entire phosphor layer The graph which shows the presence or absence of generation | occurrence | production of the initialization bright spot of PDP of an Example and a comparative example The graph which shows the brightness | luminance of PDP of an Example and a comparative example

Explanation of symbols

1 PDP
2 front panel 3 glass substrate 4 scan electrode 5 sustain electrode 6 display electrode 7 dielectric layer 8 protective film 9 back panel 10 glass substrate 11 data electrode 13 partition 14 phosphor layer 15 discharge space 16 MgO fine particle group 16a, 16b, 16c, 16d MgO fine particles

Claims (13)

A first substrate having a dielectric layer formed so as to cover the display electrode formed on the substrate and having a protective film formed on the dielectric layer; and a first substrate having a discharge space disposed opposite to the first substrate; A crystal structure having a partition wall for partitioning the discharge space and a second substrate having a phosphor layer formed between the partition walls and surrounded by a (100) plane and a (111) plane on the second substrate side Or a group of magnesium oxide particles composed of magnesium oxide particles having a crystal structure surrounded by (100), (110) and (111) planes A plasma display panel characterized by The protective film is provided with a material selected from oxides containing at least one of Mg, Ca, Sr and Ba, AlN, BN, diamond, HfN, HfC, and SiC in a surface region facing the discharge space. The plasma display panel according to claim 1, which is configured as described above. 2. The plasma display panel according to claim 1, wherein the magnesium oxide fine particle group is disposed in any region of the inside of the phosphor layer, the surface facing the discharge space of the phosphor layer, or the bottom of the phosphor layer. . 2. The plasma display panel according to claim 1, wherein the protective film is configured by disposing magnesium oxide fine particle groups having the same crystal structure as the magnesium oxide fine particle group in a surface region facing the discharge space. 5. The plasma display panel according to claim 4, wherein the protective film is composed of a base film formed on the dielectric layer and a group of magnesium oxide fine particles disposed on the base film. The magnesium oxide particle group includes fine particles having a hexahedral structure and having at least one truncated surface, wherein a major surface of the fine particles has a (100) surface and a truncated surface has a (111) surface. 2. The plasma display panel according to 1. The magnesium oxide particle group includes fine particles having an octahedral structure and having at least one truncated surface, wherein a major surface of the fine particles has a (111) surface and a truncated surface has a (100) surface. 2. The plasma display panel according to 1. The magnesium oxide fine particle group has a NaCl crystal structure, and includes fine particles that are tetradecahedrons having 6 faces corresponding to the (100) face and 8 faces corresponding to the (111) face, and the main face of the fine particles is (100). The plasma display panel according to claim 1, wherein the surface and the top surface have a (111) surface. The magnesium oxide particle group includes fine particles having a hexahedral structure and having at least one truncated top surface and at least one oblique surface, the main surface of the fine particles being the (100) plane, and the truncated surface being (111). The plasma display panel according to claim 1, wherein the plane and the oblique plane have a (110) plane. The magnesium oxide particle group includes fine particles having an octahedral structure and having at least one truncated top surface and at least one oblique surface, and the major surface of the fine particles is a (111) plane and the truncated surface is (100). The plasma display panel according to claim 1, wherein the plane and the oblique plane have a (110) plane. The magnesium oxide fine particle group has a NaCl crystal structure, and is a 26-sided fine particle having 6 faces corresponding to the (100) face, 12 faces corresponding to the (110) face, and 8 faces corresponding to the (111) face. 2. The plasma display panel according to claim 1, wherein the main surface of the fine particles has a (111) surface, an oblique surface has a (110) surface, and a truncated surface has a (100) surface. The plasma display panel according to claim 1, wherein the magnesium oxide fine particles have a particle size of 300 nm or more. The plasma display panel according to claim 1, wherein the magnesium oxide fine particles have a BET value of 2.0 m ² or less.

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