JP4476334B2 - Plasma display panel and manufacturing method thereof - Google Patents

Description

   The present invention relates to a plasma display panel and a method for manufacturing the same, and more particularly to a technique for achieving both low voltage driving and prevention of charge loss.

   A plasma display panel (hereinafter referred to as “PDP”) is a flat display device using radiation from gas discharge. High-speed display and large size are easy, and it is widely put into practical use in fields such as video display devices and public information display devices. There are two types of PDPs: DC type (DC type) and AC type (AC type). Surface discharge type AC type PDPs have a particularly high technical potential in terms of life characteristics and increase in size, and are commercialized. FIG. 8 is a schematic assembly diagram of a discharge cell structure as a discharge unit in a general AC type PDP. A PDP 1x shown in FIG. 8 is formed by bonding a front panel 2 and a back panel 9 together. In the front panel 2, a plurality of display electrode pairs 6 each including the scan electrode 5 and the sustain electrode 4 are arranged on one side of the front panel glass 3, and the dielectric layer 7 is formed so as to cover the display electrode pair 6. And the surface layer 8 is laminated | stacked one by one. The scan electrode 5 and the sustain electrode 4 are configured by laminating transparent electrodes 51 and 41 and bus lines 52 and 42, respectively.

   The dielectric layer 7 is formed of a low melting point glass having a glass softening point in the range of about 550 ° C. to 600 ° C., and has a current limiting function peculiar to the AC type PDP.

   The surface layer 8 protects the dielectric layer 7 and the display electrode pair 6 from ion collision of plasma discharge, and efficiently discharges secondary electrons and lowers the discharge start voltage. In general, the surface layer 8 is formed by vacuum vapor deposition or printing using magnesium oxide (MgO) having excellent secondary electron emission characteristics, sputtering resistance, and optical transparency. The configuration similar to that of the surface layer 8 may be provided as a protective layer for the purpose of securing secondary electron emission characteristics in addition to protecting the dielectric layer 7 and the display electrode pair 6.

   On the other hand, the back panel 9 is provided side by side so that a plurality of data (address) electrodes 11 for writing image data on the back panel glass 10 intersect the display electrode pair 6 of the front panel 2 in the orthogonal direction. A dielectric layer 12 made of low-melting glass is disposed on the back panel glass 10 so as to cover the data electrodes 11. On the boundary of the dielectric layer 12 with the adjacent discharge cells (not shown), a pattern such as a grid pattern is formed so that the partition walls (ribs) 13 made of low melting point glass define the discharge space 15. The portions 1231, 1232 are formed in combination. A phosphor layer 14 (phosphor layers 14R, 14G, and 14B) is formed on the surface of the dielectric layer 12 and the side surfaces of the partition walls 13 by applying and firing phosphor inks of R, G, and B colors.

   The front panel 2 and the back panel 9 are arranged so that the display electrode pair 6 and the data electrode 11 are orthogonal to each other with the discharge space 15 therebetween, and are sealed around each of them. At this time, the discharge space 15 sealed inside is filled with a rare gas such as a Xe—Ne or Xe—He system as a discharge gas at a pressure of about several tens of kPa. The PDP 1x is configured as described above.

In order to display an image using the PDP, a gradation expression method (for example, an intra-field time-division display method) that divides an image of one field into a plurality of subfields (SF) is used. By the way, low-power drive is desired for recent electric appliances, and there is a similar demand for PDP. In a high-definition PDP, discharge cells are miniaturized and the number of discharge cells is also increased. Therefore, there is a problem that the operating voltage is increased to increase the reliability of the write discharge. The operating voltage of the PDP depends on the secondary electron emission coefficient (γ) of the surface layer. γ is a value determined by the material and discharge gas, and it is known that γ increases as the work function of the material decreases. Therefore, Patent Document 4 describes that calcium oxide (CaO), strontium oxide (SrO), barium oxide (BaO), or the like is used as a main component of the protective layer. According to this, a high γ film having secondary electron emission characteristics better than that of MgO can be formed, and the PDP can be driven at a relatively low voltage.
JP-A-8-236028 Japanese Patent Laid-Open No. 10-334809 JP 2006-54158 A JP 2002-231129 A WO2005 / 043578

   However, if calcium oxide (CaO), strontium oxide (SrO), barium oxide (BaO), or the like is used for the protective layer, the PDP can be driven at a relatively low voltage, but the problem of “charge loss” may occur in the protective layer. “Charge loss” is a phenomenon in which excessive electrons are emitted from the protective layer when the PDP is driven. CaO, SrO, and BaO generally have higher impurity adsorptivity than MgO, and when the impurities are adsorbed, an unnecessary energy level is formed in the vicinity of the vacuum level together with oxygen vacancies in the band structure of the protective layer. These shallow energy levels induce the problem of charge loss. If charge loss occurs during PDP driving, the charge necessary for the sustain discharge cannot be held in the sustain period in the subfield, causing a discharge failure. In order to solve the problem of charge loss, it is conceivable to supply a new charge from the outside in order to hold the charge necessary for discharge. However, this increases the drive voltage, so CaO, SrO, BaO. The great merit of using is lost.

   In addition, there is a problem of “discharge delay” in the PDP. That is, in the display field such as PDP, the definition of video sources is increasing, and the number of scanning electrodes (scanning lines) is increasing in order to correctly display high-definition images. For example, in full HDTV, the number of scanning lines is more than twice that of NTSC TV. Since it is necessary to drive one field within 1/60 [s], in order to display a high-definition image on the PDP, the width of the pulse applied to the data electrode is narrowed during the writing period in the subfield. There is a need to. However, when driving the PDP, there is a problem of a time lag called “discharge delay” from the rise of the voltage pulse to the occurrence of discharge in the discharge cell. If the pulse width is shortened for high-speed driving, the influence of “discharge delay” increases, and the probability that discharge can be completed within the width of each pulse decreases. As a result, a non-light cell (lighting failure) occurs, and the image display performance is impaired. The protective layer mainly composed of MgO is modified by adding Fe, Cr, Si, or Al to the MgO crystal to make it easier to emit trigger electrons for writing discharge or sustain discharge. Although techniques for achieving high-speed driving have been made (Patent Documents 1 and 2), it is difficult to say that the same countermeasure is effective for CaO, SrO, and BaO.

   As described above, in the current PDP, there are some problems that are difficult to be compatible with each other, and there is still room to be solved.

  The present application has been made in view of the above problems, and has the following objects.

   A first object is to provide a plasma display panel that can drive a PDP at a low voltage and exhibit charge retention characteristics in the protective layer by improving the structure of the protective layer, and can be expected to exhibit good image display performance. .

   As a second purpose, in addition to the effects of lowering the voltage of the PDP and exhibiting the charge retention characteristics, it is possible to prevent the occurrence of discharge delay and to perform high-speed driving well even in a high-definition PDP. Provided is a plasma display panel that can be expected to display an image.

  In order to achieve the above object, the PDP according to the present invention is sealed in a state where the first substrate on which the display electrode is disposed is opposed to the second substrate through a discharge space filled with a discharge gas. A surface layer formed by depositing at least one of CaO, BaO, and SrO is disposed on a surface of the plasma display panel facing the discharge space of the first substrate. It was formed in an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or higher, and was configured to be a solid solution of at least two of CaO, BaO, and SrO.

  The present invention also provides a plasma display panel in which a first substrate on which display electrodes are disposed is sealed in a state facing a second substrate through a discharge space filled with a discharge gas. A surface layer is disposed on a surface of the substrate facing the discharge space, and the surface layer is formed by forming at least one of CaO, BaO, and SrO, and has a depth from the vacuum level. Only an electron level band at 2 eV or higher exists, and the structure is a solid solution of at least two of CaO, BaO, and SrO.

  Here, the surface layer can be formed in an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or more.

  The present invention also provides a plasma display panel in which a first substrate on which display electrodes are disposed is sealed in a state facing a second substrate through a discharge space filled with a discharge gas. A surface layer is disposed on a surface of the substrate facing the discharge space, and the surface layer is formed by forming at least one of CaO, BaO, and SrO, and has a depth from the vacuum level. The existence of an electronic level band at less than 2 eV is excluded, and the structure is a solid solution of at least two of CaO, BaO, and SrO.

  The present invention also provides a plasma display panel in which a first substrate on which display electrodes are disposed is sealed in a state facing a second substrate through a discharge space filled with a discharge gas. A surface layer formed by depositing at least one of CaO, BaO, and SrO is disposed on the surface facing the discharge space of one substrate. When the surface layer is irradiated with light energy, When the intensity of light energy is changed in ascending order, photoelectron emission is started with an energy of 2 eV or more, and at least two kinds of solid solutions of CaO, BaO, and SrO are used.

  Furthermore, the present invention provides a plasma display panel in which a first substrate on which display electrodes are arranged is sealed in a state facing a second substrate through a discharge space filled with a discharge gas. A surface layer formed by depositing at least one of CaO, BaO, and SrO is disposed on the surface of the substrate facing the discharge space, and MgO fine particles are disposed on the surface of the surface layer on the discharge space side. The surface layer is formed in an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or more, and is configured to be a solid solution of at least two of CaO, BaO, and SrO.

  Here, the MgO fine particles can be produced by a gas phase oxidation method. Alternatively, the MgO precursor can be obtained by firing at a temperature of 700 ° C. or higher.

  The present invention also provides a plasma display panel in which a first substrate on which display electrodes are disposed is sealed in a state facing a second substrate through a discharge space filled with a discharge gas. A surface layer formed by depositing at least one of CaO, BaO, and SrO is disposed on the surface of the substrate facing the discharge space, and MgO fine particles are disposed on the surface of the surface layer on the discharge space side. The surface layer has only an electron level band at a depth of 2 eV or more from the vacuum level, and is a solid solution of at least two of CaO, BaO, and SrO.

  Furthermore, the present invention provides a plasma display panel in which a first substrate on which display electrodes are arranged is sealed in a state facing a second substrate through a discharge space filled with a discharge gas. A surface layer formed by depositing at least one of CaO, BaO, and SrO is disposed on the surface of the substrate facing the discharge space, and MgO fine particles are disposed on the surface of the surface layer on the discharge space side. The surface layer is one in which the presence of an electron level band at a depth from the vacuum level of less than 2 eV is excluded, and is a solid solution of at least two of CaO, BaO, and SrO. The configuration.

  Further, the present invention is a plasma display panel, wherein the first substrate on which the display electrodes are disposed is sealed in a state facing the second substrate through the discharge space filled with the discharge gas, A surface layer formed by depositing at least one of CaO, BaO, and SrO is disposed on the surface of the first substrate facing the discharge space, and MgO fine particles are formed on the surface of the surface layer on the discharge space side. When the surface layer is irradiated with light energy, the surface layer starts photoemission with an energy of 2 eV or more when the intensity of the light energy is changed in ascending order, and CaO, BaO, It was set as the structure which is a solid solution of at least 2 or more types of SrO.

  Furthermore, the present invention provides a surface layer formed by forming at least one of CaO, BaO, and SrO on a first substrate on which display electrodes are provided, and an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or more. Forming a surface layer, and a sealing step for sealing the first substrate and the second substrate with the surface layer facing the discharge space via the discharge space, and forming the surface layer In the process, a method for manufacturing a plasma display panel in which the surface layer is formed of at least two kinds of solid solutions of CaO, BaO, and SrO is used.

  Here, in the surface layer forming step, the surface layer can be formed by one or more of a vapor deposition method, a sputtering method, and an ion plating method.

  The present invention also provides a surface layer formed by forming at least one of CaO, BaO, and SrO on a first substrate on which display electrodes are provided, and an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or more. Surface layer forming step to be formed below, MgO fine particle disposing step for disposing MgO fine particles on the surface layer, and a state in which the surface layer faces the discharge space through the discharge space between the first substrate and the second substrate In the surface layer forming step, the surface layer is formed of at least two kinds of solid solutions of CaO, BaO, and SrO.

   Here, in the MgO fine particle arranging step, MgO fine particles produced by a vapor phase oxidation method can also be used. Alternatively, MgO fine particles prepared by firing an MgO precursor at a temperature of 700 ° C. or higher can be used.

   With the configuration of the surface layer, the PDP can be driven at a low voltage and the charge retention characteristics can be improved in the protective layer.

   In addition to the above effects, the configuration in which the MgO fine particles are arranged on the surface layer can realize high-speed driving by suppressing the occurrence of discharge delay.

   Here, the combination of the surface layer and the MgO fine particles in the present invention generally has a configuration corresponding to a protective layer provided for the purpose of protecting the dielectric layer in the PDP.

   Embodiments and examples of the present invention will be described below, but the present invention is naturally not limited to these forms, and may be appropriately modified and implemented without departing from the technical scope of the present invention. be able to.

<Embodiment 1>
(PDP configuration example)
FIG. 1 is a schematic cross-sectional view along the xz plane of the PDP 1 according to Embodiment 1 of the present invention. The PDP 1 is generally the same as the conventional configuration (FIG. 8) except for the configuration around the protective layer.

   Here, the PDP 1 is an AC type of the 42-inch class NTSC specification example, but the present invention may naturally be applied to other specification examples such as XGA and SXGA. As a high-definition PDP having a resolution higher than HD (High Definition), for example, the following standard can be exemplified. When the panel sizes are 37, 42, and 50 inches, they can be set to 1024 × 720 (number of pixels), 1024 × 768 (number of pixels), and 1366 × 768 (number of pixels) in the same order. In addition, a panel having a higher resolution than that of the HD panel can be included. A panel having a resolution of HD or higher can include a full HD panel having 1920 × 1080 (number of pixels).

   As shown in FIG. 1, the configuration of the PDP 1 is roughly divided into a front panel 2 and a back panel 9 that are disposed with their main surfaces facing each other.

A front panel glass 3 serving as a substrate of the front panel 2 has a pair of display electrodes 6 (scanning electrodes 5 and sustaining electrodes 4) disposed on one main surface thereof with a predetermined discharge gap (75 μm). It is formed over multiple pairs. Each display electrode pair 6 includes strip-shaped transparent electrodes 51 and 41 (thickness 0.1 μm, width 150 μm) made of a transparent conductive material such as indium tin oxide (ITO), zinc oxide (ZnO), and tin oxide (SnO ₂ ). ), Bus lines 52 and 42 (42 μm) made of Ag thick film (thickness 2 μm to 10 μm), Al thin film (thickness 0.1 μm to 1 μm), Cr / Cu / Cr laminated thin film (thickness 0.1 μm to 1 μm), or the like. 7 μm thick and 95 μm wide) are laminated. The sheet resistance of the transparent electrodes 51 and 41 is lowered by the bus lines 52 and 42.

   Here, the “thick film” refers to a film formed by various thick film methods formed by applying a paste containing a conductive material or the like and then baking it. The “thin film” refers to a film formed by various thin film methods using a vacuum process, including a sputtering method, an ion plating method, an electron beam evaporation method, and the like.

The front panel glass 3 provided with the display electrode pair 6 has a low melting point glass mainly composed of lead oxide (PbO), bismuth oxide (Bi ₂ O ₃ ), or phosphorus oxide (PO ₄ ) over the entire main surface. A dielectric layer 7 having a thickness of 35 μm is formed by a screen printing method or the like.

   The dielectric layer 7 has a current limiting function peculiar to the AC type PDP, and is an element that realizes a longer life than the DC type PDP.

   On the surface of the dielectric layer 7 on the discharge space side, a surface layer 8 having a film thickness of about 1 μm and MgO fine particles 16 are dispersed and disposed on the surface of the surface layer 8. The combination of the surface layer 8 and the MgO fine particles 16 constitutes a protective layer for the dielectric layer 7.

   The surface layer 8 is disposed for the purpose of protecting the dielectric layer 7 from ion bombardment during discharge and reducing the discharge start voltage, and is made of a material excellent in sputtering resistance and secondary electron emission coefficient γ. . The material has better optical transparency and electrical insulation. On the other hand, the MgO fine particles 16 are disposed in order to exhibit high initial electron emission characteristics.

   Thereby, in the protective layer, the characteristics of the surface layer 8 and the MgO fine particles 16 that are functionally separated from each other are synergistically exhibited. Further, impurities can be prevented from adhering from the discharge space 15 in the covered region of the MgO fine particles 16 on the surface of the surface layer 8, and the life characteristics of the PDP 1 can be improved. Details of the surface layer 8 and the MgO fine particles 16 will be described later. For the sake of explanation, FIG. 1 schematically shows the MgO fine particles 16 disposed on the surface of the surface layer 8 larger than the actual size.

   A back panel glass 10 serving as a substrate of the back panel 9 has an Ag thick film (thickness 2 μm to 10 μm), an Al thin film (thickness 0.1 μm to 1 μm) or a Cr / Cu / Cr laminated thin film ( The data electrodes 11 having a thickness of 0.1 μm to 1 μm are arranged in parallel in a stripe shape at a constant interval (360 μm) in the y direction with a width of 100 μm and a longitudinal direction in the x direction. A dielectric layer 12 having a thickness of 30 μm is disposed over the entire surface of the back panel glass 9 so as to enclose each data electrode 11.

   On the dielectric layer 12, a grid-like partition wall 13 (height: about 110 μm, width: 40 μm) is further arranged in accordance with the gap between the adjacent data electrodes 11, and the discharge cells are partitioned to prevent erroneous discharge. It plays a role in preventing the occurrence of optical crosstalk.

   A phosphor layer 14 corresponding to each of red (R), green (G), and blue (B) for color display is provided on the side surface of two adjacent barrier ribs 13 and the surface of the dielectric layer 12 therebetween. Is formed. The dielectric layer 12 is not essential, and the data electrode 11 may be directly enclosed by the phosphor layer 14.

The front panel 2 and the back panel 9 are disposed to face each other so that the longitudinal directions of the data electrode 11 and the display electrode pair 6 are orthogonal to each other, and the outer peripheral edges of both the panels 2 and 9 are sealed with glass frit. A discharge gas composed of an inert gas component containing He, Xe, Ne or the like is sealed between the panels 2 and 9 at a predetermined pressure.

   A space between the barrier ribs 13 is a discharge space 15. A region where a pair of adjacent display electrode pairs 6 and one data electrode 11 intersect with each other across the discharge space 15 is a discharge cell (“subpixel”) for image display. To say). The discharge cell pitch is 675 μm in the x direction and 300 μm in the y direction. One discharge pixel (675 μm × 900 μm) is composed of three discharge cells corresponding to adjacent RGB colors.

   As shown in FIG. 2, scan electrode driver 111, sustain electrode driver 112, and data electrode driver 113 are connected to scan electrode 5, sustain electrode 4 and data electrode 11 as drive circuits, respectively, as shown in FIG.

(PDP drive example)
In the PDP 1 having the above-described configuration, an AC voltage of several tens to several hundreds of kHz is applied to the gap between the display electrode pairs 6 by a known drive circuit (not shown) including the drivers 111 to 113 during driving. As a result, a discharge is generated in an arbitrary discharge cell, and ultraviolet rays (dotted lines and arrows in FIG. 1) containing a resonance line mainly composed of a wavelength of 147 nm due to excited Xe atoms and a molecular line mainly composed of a wavelength of 173 nm due to excited Xe molecules are emitted from the phosphor layer 14. Is irradiated. The phosphor layer 14 is excited to emit visible light. 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 (SF), and each subfield is further divided into a plurality of periods. One subfield further includes (1) an initialization period in which all discharge cells are initialized, and (2) each discharge cell is addressed, and a display state corresponding to input data is selected and input to each discharge cell. The period is divided into four periods: an address (writing) period, (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.

   In each subfield, after resetting the wall charge of the entire screen with the initialization pulse in the initialization period, a write discharge is performed in which the wall charge is accumulated only in the discharge cells to be lit in the write period, and the subsequent discharge sustain period In this case, by applying an alternating voltage (sustain voltage) to all the discharge cells at once, the discharge is maintained for a certain period of time so that light emission 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, an address period, a discharge sustain period, and an erase period are allocated to each subfield.

   The initialization period is a period in which the wall charges on the entire screen are erased (initialization discharge) in order to prevent the influence of lighting of the discharge cells before that (influence of the accumulated wall charges). In the drive waveform example shown in FIG. 3, a higher voltage (initialization pulse) than the data electrode 11 and the sustain electrode 4 is applied to the scan electrode 5 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 among the data electrode 11, the scan electrode 5 and the sustain electrode 4, so that the surface layer 8 near the scan electrode 5 and the surface of the MgO fine particle 16 Negative charges are accumulated as wall charges. Further, positive charges are accumulated as wall charges on the surface of the phosphor layer 14 near the data electrode 11, the surface layer 8 near the sustain electrode 4, and the surface of the MgO fine particles 16. Due to this wall charge, a predetermined wall potential is generated between scan electrode 5 and data electrode 11 and between scan electrode 5 and sustain electrode 4.

   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 4 is applied to the scanning electrode 5. That is, a voltage is applied to scan electrode 5 -data electrode 11 in the same direction as the wall potential, and a data pulse is applied between scan electrode 5 and sustain electrode 4 in the same direction as the wall potential, thereby writing discharge (writing Discharge)). As a result, negative charges are accumulated on the surface of the phosphor layer 14, the surface layer 8 near the sustain electrode 4, and the surface of the MgO fine particle 16, and the positive charge is accumulated on the surface layer 8 near the scan electrode 5 and the surface of the MgO fine particle 16. Are accumulated as wall charges. Thus, a predetermined wall potential is generated between sustain electrode 4 and scan electrode 5.

   The discharge maintaining period is a period in which the lighting state set by the write discharge is expanded and the discharge is maintained in order to ensure the luminance corresponding to the gradation. Here, in the discharge cell in which the wall charges are present, a voltage pulse (for example, a rectangular wave voltage of about 200 V) for sustain discharge is applied to each of the pair of scan electrodes 5 and sustain electrodes 4 in different phases. 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 excited Xe atoms in the discharge space, and a molecular beam mainly composed of 173 nm is emitted from 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 wall charges are not written on the surface layer 8, no sustain discharge occurs and the display state is black.

   In the erasing period, a gradual erasing pulse is applied to the scanning electrode 5 to erase wall charges.

[About surface layer 8]
The surface layer 8 contains at least one of CaO, SrO, and BaO as a main component, and is any one of a sputtering method, an ion plating method, a vapor deposition method, etc. in an oxygen partial pressure atmosphere at a pressure of 0.025 Pa or more. The film is formed by the method, and exhibits the effect of reducing the discharge start voltage and improving charge loss.

(Reduction of discharge start voltage)
The surface layer 8 contains at least one of CaO, SrO, and BaO as a main component. The energy level that exists as an electron level unique to CaO, SrO, and BaO exists in a region that is shallower than the vacuum level compared to MgO. Therefore, when driving the PDP 1, when electrons existing in the energy level existing as the electron levels specific to CaO, SrO, and BaO transition to the ground state of the Xe ion, they are subjected to the Auger effect of another electron. The amount of energy acquired in this way is larger than in the case of MgO. This amount of energy is sufficient for electrons to be emitted beyond the vacuum level. As a result, the surface layer 8 exhibits better secondary electron emission characteristics as compared with the case where the material is MgO.

   Specifically, the energy level that exists as an intrinsic electron level in CaO, SrO, and BaO exists in a region whose depth from the vacuum level is 6.05 eV or less. The existing energy level exists in a region where the depth from the vacuum level exceeds 6.05 eV.

   Hereinafter, the grounds for the existence of a specific electron level in the above region will be described in detail using the explanation of the state transition path of electrons accompanying the exchange of energy between the surface layer 8 and the gas sealed in the discharge space.

   When ions due to the discharge gas generated in the discharge space approach the surface of the surface layer 8 to the point where interaction is possible, electrons existing in the electron level inherent to the material constituting the surface layer 8 are discharged into the discharge gas. By transitioning to the ground state of the ions, another electron caused the Auger effect, and the depth of the ground state level of the discharge gas ions was subtracted from the depth of the electronic level inherent to the material constituting the surface layer 8. An energy of a minute is obtained, and secondary electrons are emitted by jumping over the energy gap up to the vacuum level (refer to Patent Document 5 for details).

   As shown in FIG. 4, the Xe ion has a ground state energy level at a depth of 12.1 eV from the vacuum level in the band structure. Therefore, when the electron level specific to the material constituting the surface layer 8 exists in a region shallower than 6.05 eV, which is half of the above 12.1 eV ((a) in FIG. 4), the level of the ionized state The energy gap to the vacuum level is obtained by obtaining the energy (greater than 6.05 eV) by subtracting the depth of the electron level specific to the material constituting the surface layer 8 from the depth of the position (12.1 eV). Can jump over and release electrons. On the contrary, when the electron level intrinsic to the material constituting the surface layer 8 exists at a level deeper than 6.05 eV, which is half of the above 12.1 eV ((b) in FIG. 4), Even if the energy (less than 6.05 eV) obtained by subtracting the electron level depth inherent in the material constituting the surface layer 8 from the level depth (12.1 eV) is obtained, The energy gap cannot be jumped and electrons cannot be emitted.

   On the other hand, according to another experiment by the inventor, the discharge starting voltage when Xe is used as the discharge gas is that the protective layer mainly composed of MgO is the same as in the first embodiment mainly composed of CaO, BaO, SrO. It was confirmed that the height was higher than that of the surface layer 8. This tendency was more prominent in proportion to the Xe partial pressure in the discharge gas.

   From the above, the energy level that exists as an intrinsic electron level in CaO, SrO, and BaO exists in a region within 6.05 eV, and the energy level that exists as an intrinsic electron level in MgO is a vacuum level. Can be considered to exist in a region where the depth from the top is over 6.05 eV.

   In general, the sum of the band gap and electron affinity specific to each material is about 8.8 eV for MgO, about 8.0 eV for CaO, about 6.9 eV for SrO, and about 5.2 eV for BaO. . This is an observed value of the bulk portion in the surface layer 8. On the other hand, in the present invention, the sum of the band gap and electron affinity of MgO is larger than 6.05 eV, and the sum of the band gap and electron affinity of CaO, BaO, and SrO is considered to be 6.05 eV or less. Also, a decrease of 2 eV was observed. This is because the sum of the band gap and the electron affinity in the first embodiment is an observed value of the surface portion of the surface layer 8 that actually affects the discharge. The reason why the band gap near the surface is smaller than the bulk band gap in the surface layer 8 is that, in the surface portion, unlike the internal state, the atoms exposed to the surface side are in a disconnected state. Conceivable.

   The “surface portion” refers to a depth from the outermost surface of the surface layer 8 to about several tens of atomic layers.

(About improvement of charge loss)
The surface layer 8 is formed with a crystal structure with few impurities and oxygen vacancies by depositing one or more of CaO, SrO, and BaO in an oxygen partial pressure atmosphere of 0.025 Pa or more. Therefore, unnecessary energy levels in the vicinity of the vacuum level are eliminated, and only an electron level band having a depth from the vacuum level of 2 eV or more exists. That is, in the surface layer 8 in the first embodiment, the presence of an electron level band having a depth from the vacuum level of less than 2 eV is excluded. This suppresses excessive emission of electrons from the unnecessary energy level close to the vacuum level when the PDP is driven, and in addition to the effect of achieving both the low voltage driving and the secondary electron emission characteristics, The effect of the electron holding property is also exhibited. This charge retention characteristic is particularly effective for retaining wall charges stored during the initialization period and preventing write defects during the write period to perform reliable write discharge.

   Specifically, the unnecessary energy level in the vicinity of the vacuum level is an energy level having a depth of less than 2 eV from the vacuum level in the energy band.

   Hereinafter, the above grounds will be described in detail using the results of cathodoluminescence measurement in a protective layer made of an alkaline earth metal oxide.

   FIG. 5 shows the results of cathodoluminescence measurement of protective layers (sample A and sample B) made of alkaline earth metal oxide. The energy of the irradiation electron beam is 3 kV, and the measurement wavelength region is 200 to 900 nm. The horizontal axis represents the value obtained by converting the detected wavelength into energy. Both Sample A and Sample B have strong emission spectra near 3 eV. In sample A, almost no emission spectrum was observed near 1-2 eV, and in sample B, a strong emission spectrum was observed near 1-2 eV.

   On the other hand, another experiment by the inventor confirmed that the PDP using the protective layer of Sample A has a characteristic that there is no non-lighted cell due to charge loss at a normal setting drive voltage, and charge is not easily lost. It was. In addition, in the PDP using the protective layer of Sample B, it was confirmed that there is a non-lighted cell due to charge loss at a normal setting drive voltage, and the charge is easily lost. From the above, it can be considered that the electrons that are excessively released when the PDP is driven are electrons that occupy an energy level that is less than 2 eV in depth from the vacuum level in the energy band.

(Confirmation method)
The surface layer 8 according to the first embodiment is excluded from the energy level in which the depth from the vacuum level is less than 2 eV in the energy band. The surface layer mainly composed of CaO, BaO, and SrO This is confirmed by the result of measuring the amount of electrons emitted from the surface layer 8 when the light is irradiated to the surface 8. Electron emission (photoelectron emission) starts only when electrons existing in the electron level band acquire energy by the amount of energy of the irradiated light and acquire energy sufficient to exceed the energy gap up to the vacuum level. Because it is done. In other words, in the surface layer 8 from which the energy level existing at less than 2 eV is excluded, when the energy of the light applied to the surface layer 8 is changed in ascending order, emission of electrons starts at an energy of 2 eV or more. It is.

On the other hand, the protective layer (for example, Patent Document 4) formed using CaO, SrO, and BaO in an oxygen atmosphere of about 0.01 Pa has many levels due to oxygen deficiency at an energy level of less than 2 eV. Since it is formed, it can be considered that electron emission is started even by energy of less than 2 eV. That is, the energy level that exists as an electron level unique to CaO, SrO, and BaO exists in a region within 6.05 eV in the surface portion of the surface layer 8, and the energy level of less than 2 eV in the surface layer 8. By adopting a configuration in which unnecessary energy levels due to oxygen deficiency or the like do not exist in the position, both reduction of the discharge start voltage and improvement of charge loss can be achieved. Here, light refers to a wide range of light such as X-rays, ultraviolet rays, and infrared rays.

   Note that the surface layer 8 in Embodiment 1 has only an electron level band whose depth from the vacuum level is 2 eV or more, or an electron level band whose depth from the vacuum level is less than 2 eV. However, a certain amount of electron level bands may be present below 2 eV as long as the effect of the present invention is obtained.

   Furthermore, in the first embodiment, the surface layer 8 is composed of at least one of CaO, SrO, and BaO as a main component. Among these, CaO has a relatively low impurity adsorptivity and high purity. It is suitable for obtaining the crystal structure of Moreover, when the surface layer 8 is configured as a solid solution of CaO, SrO, and BaO, it has an effect of suppressing adsorption of impurities in the layer, and it is found that it is more preferable than configuring the layer from a single material for a plurality of reasons. Yes.

   As described above, a layer (for example, the protective layer described in Patent Document 4) formed using CaO, SrO, or BaO in an oxygen atmosphere of about 0.01 Pa is formed with a crystal structure with many oxygen vacancies. Therefore, electrons are excessively emitted from the unnecessary energy level close to the vacuum level when the PDP is driven. In this case, there is a measure for increasing the drive voltage in order to supplement the retention of the wall charge. However, in the present invention, such a measure is unnecessary, and power consumption can be reduced by driving at a low voltage. Furthermore, it is not necessary to take a countermeasure against the withstand voltage of the drive circuit corresponding to a high drive voltage, and there is a great merit in terms of reducing the manufacturing cost.

   Conventionally, there is a technique in which an energy level is provided at a depth within 4 eV from the vacuum level by doping an impurity in the protective layer or by providing an oxygen deficient portion (see Patent Document 5 for details), Such a configuration does not reach the present invention in the life characteristics of the PDP. That is, energy levels that are not inherent to the main component of the original protective layer, such as impurities and oxygen vacancies in the protective layer, are gradually lost as the crystal structure of the protective layer changes as the PDP is used over time. On the other hand, the PDP 1 has a unique energy level in the main component of the surface layer 8 and has a high merit that a stable secondary electron emission characteristic is exhibited over a long period of time.

[About MgO fine particles 16]
The MgO fine particles 16 have been confirmed by the inventor's experiments mainly to suppress the “discharge delay” in the write discharge and to improve the temperature dependency of the “discharge delay”. Therefore, in the first embodiment, the MgO fine particles 16 are arranged as an initial electron emission portion at the time of driving by utilizing the property that is superior in the advanced initial electron emission characteristics as compared with the surface layer 8.

   The “discharge delay” is considered to be mainly caused by a shortage of the amount of initial electrons that are triggered from the surface layer 8 being discharged into the discharge space 15 at the start of discharge. Therefore, in order to effectively contribute to the electron emission property to the discharge space 15, the MgO fine particles 16 are dispersed and arranged on the surface of the surface layer 8 to ensure a wide surface area. As a result, abundant electrons are released from the MgO fine particles 16 at the initial stage of driving, and the discharge delay can be eliminated. Therefore, such initial electron emission characteristics enable high-speed driving with good discharge response even when the PDP 1 has a high definition. In the configuration in which the group of MgO fine particles 16 is provided on the surface of the surface layer 8, in addition to the effect of mainly suppressing the “discharge delay” in the write discharge, the effect of improving the temperature dependency of the “discharge delay” is also obtained.

   As described above, in the PDP 1, a high-definition PDP is obtained as a whole of the PDP 1 by combining the surface layer 8 that achieves both low voltage driving and charge retention effects in the surface layer 8 and the MgO fine particles 16 that have the effect of preventing discharge delay. However, it is possible to expect high-quality image display performance in which high-speed driving can be driven at a low voltage and generation of unlit cells is suppressed.

   Further, the MgO fine particles 16 are provided on the surface of the surface layer 8 so as to have a certain protective effect on the surface layer 8. That is, the surface layer 8 has a high secondary electron emission coefficient and enables low voltage driving of the PDP, but has a relatively high adsorptivity for impurities such as water, carbon dioxide, and hydrocarbons. When adsorption of impurities occurs, initial characteristics of discharge such as secondary electron emission characteristics are impaired. Therefore, if such a surface layer 8 is coated with the MgO fine particles 16, it is possible to prevent impurities from adhering to the surface of the surface layer 8 from the discharge space 15 in the coated region. Thereby, the life characteristic of PDP1 can be improved.

<Embodiment 2>
The second embodiment of the present invention will be described focusing on the differences from the first embodiment. FIG. 6 is a cross-sectional view showing a configuration of the PDP according to the second exemplary embodiment.

   In the first embodiment, the protective layer is configured by dispersing and arranging MgO fine particles 16 on the surface layer 8. However, when the panel standard is not a single-scan driving of full HD (vertical 900 lines or more) but a double-scan driving, or a general HD (vertical 800 lines or less) or VGA standard, the PDP is high-speed. Less drive is required. In this case, it can be said that the necessity of preventing the discharge delay when the MgO fine particles 16 are disposed and the PDP is driven at high speed is low.

   The PDP 1a according to the second embodiment has a configuration applicable in such a case. Specifically, as shown in FIG. 6, the protective layer is composed only of the surface layer 8a. That is, the surface layer 8a is formed by depositing at least one of BaO, CaO, and SrO in an oxygen atmosphere.

   According to the PDP 1a of the second embodiment having the above surface layer 8a, the surface layer 8a mainly composed of at least one of BaO, CaO, and SrO formed by processing in an oxygen atmosphere during driving. As a result, good secondary electron emission characteristics are exhibited. As a result, the PDP 1a can be driven at a low voltage as in the first embodiment. Furthermore, the surface layer 8a is formed with high purity by being deposited in an oxygen partial pressure atmosphere of 0.025 Pa or higher, and generation of unnecessary energy levels of less than 2 eV is suppressed. As a result, excessive electron emission from the unnecessary energy level is prevented, and the problem of charge loss is suppressed. Thus, in the second embodiment, generation of unlit cells is prevented under low voltage driving. In this way, excellent image display performance can be demonstrated.

<Manufacturing method of PDP>
Next, an example of a method for manufacturing PDPs 1 and 1a in the above embodiments will be described. The difference between the PDP 1 and 1a is substantially only the presence or absence of the MgO fine particles 16, and the other manufacturing steps are common.

(Production of back panel)
On the surface of the back panel glass 10 made of soda-lime glass having a thickness of about 2.6 mm, a conductor material mainly composed of Ag is applied in a stripe pattern at a predetermined interval by screen printing, and a thickness of several μm (for example, About 5 μm) of data electrodes. As an electrode material of the data electrode 11, materials such as metals such as Ag, Al, Ni, Pt, Cr, Cu, and Pd, conductive ceramics such as carbides and nitrides of various metals, combinations thereof, or combinations thereof are used. A laminated electrode formed by laminating can also be used as necessary.

   Here, in order to set the PDP 1 to be manufactured to the 40-inch class NTSC standard or VGA standard, the interval between two adjacent data electrodes 11 is set to about 0.4 mm or less.

Subsequently, a glass paste made of lead-based or non-lead-based low-melting glass or SiO ₂ material is applied over the entire surface of the back panel glass 10 on which the data electrodes are formed to a thickness of about 20 to 30 μm, and fired. Form a layer.

   Next, partition walls 13 are formed in a predetermined pattern on the surface of the dielectric layer 12. Apply low-melting-point glass material paste and use a sandblasting method or a photolithography method to form a grid pattern that partitions rows and columns into multiple arrays of discharge cells so as to partition the border with adjacent discharge cells (not shown) Form with a pattern.

   Once the barrier ribs 13 are formed, the red (R) phosphor and the green (G) phosphor normally used in the AC type PDP are formed on the wall surfaces of the barrier ribs 13 and the surface of the dielectric layer 12 exposed between the barrier ribs 13. The fluorescent ink containing any one of the blue (B) phosphors is applied. This is dried and fired to form phosphor layers 14 respectively.

   Examples of applicable chemical compositions of RGB color fluorescence are as follows.

Red phosphor; (Y, Gd) BO ₃ : Eu
Green phosphor; Zn ₂ SiO ₄ : Mn
Blue phosphor; BaMgAl ₁₀ O ₁₇ : Eu
Each phosphor material preferably has an average particle diameter of 2.0 μm. This is put in a server at a rate of 50% by mass, 1.0% by mass of ethyl cellulose and 49% by mass of a solvent (α-terpineol) are added, and stirred and mixed in a sand mill to obtain 15 × 10 ⁻³ Pa · s. A phosphor ink is prepared. And this is sprayed and applied between the partition walls 13 from a nozzle having a diameter of 60 μm by a pump. At this time, the panel is moved in the longitudinal direction of the partition wall 13 and the phosphor ink is applied in a stripe shape. Thereafter, the phosphor layer 14 is formed by baking at 500 ° C. for 10 minutes.

   Thus, the back panel 9 is completed.

   In the above method example, the front panel glass 3 and the back panel glass 10 are made of soda lime glass. However, this is given as an example of the material and may be made of other materials.

(Preparation of front panel 2)
The display electrode 6 is produced on the surface of a front panel glass made of soda lime glass having a thickness of about 2.6 mm. Here, an example in which the display electrode 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 the front panel glass in a predetermined pattern such as stripes with a final thickness of about 100 nm and dried. Thereby, the transparent electrodes 41 and 51 are produced.

   On the other hand, a pattern of the display electrode 6 to be formed is prepared by preparing a photosensitive paste obtained by mixing a photosensitive resin (photodegradable resin) with Ag powder and an organic vehicle, and applying the paste on the transparent electrode material. Cover with a mask. 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, bus lines 42 and 52 having a final thickness of several μm are formed on the transparent electrodes 41 and 51. According to this photomask method, the bus lines 42 and 52 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 a metal material of the bus lines 42 and 52, 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 lines 42 and 52 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 made 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, or the like is applied on the display electrode 6. . 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.

(Deposition of surface layer 8 or 8a)
The surface layer 8 in the first embodiment and the surface layer 8a in the second embodiment can be formed by the following forming process.

   On the surface of the dielectric layer 7, at least one selected from CaO, SrO, and BaO is used as a film forming material, and is formed in an oxygen atmosphere. In addition, the film can also be formed as a solid solution in which the above oxides are dissolved.

   As a film forming method, a known method such as an electron beam evaporation method, a sputtering method, or an ion plating method can be applied. In the atmosphere at the time of film formation, oxygen is set to a pressure of 0.025 Pa or more. The practical upper limit of the pressure is determined by the film formation rate. As an example, 1 Pa is considered as the upper limit of the pressure that can be actually taken in 1 Pa in the sputtering method and 0.1 Pa in the EB vapor deposition method, which is an example of the vapor deposition method.

   In addition, the atmosphere during film formation is a sealed state that is shut off from the outside and uses dry gas in order to prevent moisture adhesion and adsorption of impurities during the film formation of the surface layer 8 (surface layer 8a). Use a dry atmosphere. The dry gas has a dew point of −20 ° C. or lower, preferably −40 ° C. or lower (refer to Patent Document 4 for details).

   By adjusting the atmosphere at the time of film formation, formation of unnecessary electron levels due to impurities and oxygen defects is suppressed, and the surface layer has only an electron level band having a depth of 2 eV or more from the vacuum level. It is eight.

   Next, when producing the PDP 1 in the first embodiment, it is necessary to prepare the MgO fine particles 16. The MgO fine particles 16 can be produced by any of the following vapor phase synthesis method or precursor firing method in order to be prepared as a powder material.

[Gas phase synthesis]
A magnesium metal material (purity 99.9%) is heated in an atmosphere filled with an inert gas. While maintaining this heating state, a small amount of oxygen is introduced into the atmosphere, and magnesium is directly oxidized to produce MgO fine particles 16.

[Precursor firing method]
In this method, the MgO precursor exemplified below is uniformly fired at a high temperature (eg, 700 ° C. or higher), and this is gradually cooled to obtain MgO fine particles. Examples of the MgO precursor include magnesium alkoxide (Mg (OR) ₂ ), magnesium acetylacetone (Mg (acac) ₂ ), magnesium hydroxide (Mg (OH) ₂ ), magnesium carbonate, magnesium chloride (MgCl ₂ ), and magnesium sulfate. It is possible to select at least one of (MgSO ₄ ), magnesium nitrate (Mg (NO ₃ ) ₂ ), and magnesium oxalate (MgC ₂ O ₄ ) (two or more may be used in combination). it can. Depending on the selected compound, it may usually take the form of a hydrate, but such a hydrate may be used.

   The magnesium compound used as the MgO precursor is adjusted so that the purity of MgO obtained after firing is 99.95% or more, and the optimum value is 99.98% or more. This is because, when a certain amount or more of impurity elements such as various alkali metals, B, Si, Fe, and Al are mixed in the magnesium compound, undesired interparticle adhesion and sintering are caused during heat treatment, and highly crystalline MgO fine particles are formed. This is because it is difficult to obtain. For this reason, the precursor is adjusted in advance by removing the impurity element.

   The MgO fine particles 16 obtained by any of the above methods are dispersed in a solvent. Then, the dispersion is dispersed and dispersed on the surface of the surface layer 8 based on a spray method, a screen printing method, or an electrostatic coating method (MgO fine particle disposing step). Thereafter, the solvent is removed through a drying / firing process, and the MgO fine particles 16 are fixed on the surface of the surface layer 8.

(PDP completion)
The produced front panel 2 and back panel 9 are bonded together using sealing glass. Thereafter, the inside of the discharge space 15 is evacuated to about a high vacuum (1.0 × 10 ⁻⁴ Pa), and a Ne—Xe system or a He—Ne—Xe system is used at a predetermined pressure (66.5 kPa to 101 kPa in this case). And discharge gas such as Ne—Xe—Ar system.

   The PDP 1 or 1a is completed through the above steps.

<Performance evaluation experiment>
[Experiment 1]
A protective layer made of BaO (corresponding to the surface layer 8a of the second embodiment) was formed by sputtering, and the relationship between the partial pressure of oxygen in the film formation atmosphere and the charge release voltage was examined. FIG. 7 shows the result (relation between oxygen partial pressure and charge release voltage during film formation). As for the value of the charge release voltage, the value when oxygen is not added to the film formation atmosphere is set to 1, and the relative value is plotted.

   As a result of the experiment, as shown in FIG. 7, it was confirmed that the charge release voltage value decreased as the oxygen partial pressure in the film forming atmosphere increased. This is because oxygen added to the deposition atmosphere suppresses the formation of shallow electron levels due to oxygen vacancies in the forbidden band of the protective layer, so that excessive electron emission from the protective layer is suppressed and constant. This is thought to be because the charge retention characteristics were ensured.

   On the other hand, when the relative value of the charge removal voltage becomes larger than 0.5, a non-lighted cell starts to be generated under a set voltage necessary for driving.

   From the results of the above experiments, it was found that a suitable oxygen partial pressure in the film formation atmosphere was 0.025 Pa or more. In addition, as a result of another experiment conducted by the inventors of the present application, the same results as in FIG. 7 were obtained even in a film produced by using the EB vapor deposition method or the ion plating method. Further, it was found that even when CaO or SrO was used as the material for the protective layer, the same results as in FIG. 7 were obtained.

   Here, as a conventional film forming method, there is a technique for forming a protective layer using CaO, SrO, and BaO in an oxygen atmosphere of about 0.01 Pa (for example, Patent Document 4). However, it can be seen from FIG. 7 that the surface layer of the present invention cannot be obtained with such an oxygen partial pressure value. That is, when the oxygen partial pressure in the film-forming atmosphere is about 0.01 Pa, the charge release voltage is close to 1.0, which is almost the same as when no oxygen is added to the film-forming atmosphere.

   Therefore, in order to effectively prevent the problem of charge loss in the PDP, as described above, the oxygen partial pressure should be at least 0.025 Pa or more.

   Furthermore, a more remarkable improvement effect can be obtained by setting the oxygen partial pressure to 0.2 Pa or more.

[Experiment 2]
Next, the following PDPs of Samples 1 to 11 were prepared. Here, samples 7 and 8 (Examples 1 and 2) correspond to the configuration of the second embodiment, and samples 10 and 11 (Examples 4 and 5) correspond to the configuration of the first embodiment.

   Sample 1 (Comparative Example 1): A surface layer made of MgO was used as the most basic conventional PDP configuration.

   Sample 2 (Comparative Example 2): A surface layer made of MgO doped with Al.

   Sample 3 (Comparative Example 3): MgO fine particles obtained by firing an MgO precursor on a surface layer made of MgO were dispersed by a printing method.

   Sample 4 (Comparative Example 4): A laminated body in which MgO fine particles obtained by firing an MgO precursor on a surface layer made of MgO doped with Al were dispersed by a printing method.

   Sample 5 (Comparative Example 5): A surface layer made of BaO formed under an oxygen partial pressure of 0 Pa (no oxygen).

   Sample 6 (Comparative Example 6): MgO fine particles produced by a vapor phase method were dispersed by a spray method on a surface layer made of BaO formed under an oxygen partial pressure of 0 Pa (no oxygen). .

   Sample 7 (Example 1): A surface layer made of BaO formed under an oxygen partial pressure of 0.2 Pa.

   Sample 8 (Example 2): A surface layer made of SrO formed under an oxygen partial pressure of 0.05 Pa.

   Sample 9 (Example 3): A surface layer made of CaO was formed under an oxygen partial pressure of 0.05 Pa.

   Sample 10 (Example 4): MgO fine particles produced by a vapor phase method were dispersed by a spray method on a surface layer made of BaO formed under an oxygen partial pressure of 0.2 Pa.

   Sample 11 (Example 5): a structure in which MgO fine particles produced by firing an MgO precursor on a surface layer made of CaO formed under an oxygen partial pressure of 0.05 Pa were dispersed by a spray method; did.

(Measurement of discharge start voltage)
With respect to the prepared PDPs of Samples 1 to 11, the value of the discharge start voltage was measured when 100% of the Xe-Ne mixed gas or Xe gas having a Xe partial pressure of 15% was used as the discharge gas.

(Measurement of discharge delay time and charge loss)
When a Ne—Xe mixed gas having a Xe partial pressure of 15% was used as the discharge gas, the discharge delay and the charge loss in the write discharge were evaluated. As an evaluation method, a pulse corresponding to the initialization pulse in the drive waveform example shown in FIG. 3 was applied to an arbitrary discharge cell in the PDP of each sample 1 to 11, and then a data pulse and a scan pulse were applied. The statistical delay of the discharge that sometimes occurs was measured.

   Further, after applying a pulse corresponding to the initialization pulse, an applied voltage required to hold the wall charge was measured, and this was measured as a voltage for eliminating charge.

   In any measurement, the panel temperature was 25 ° C.

   Table 1 shows the results of each experiment conducted under the above conditions.

（実験結果）
表１の結果から、実施の形態１の構成に相当するサンプル１０及び１１（実施例４及び５）は、サンプル１〜６（比較例１〜６）に比べ、放電開始電圧の低減効果、放電遅れ時間の低減効果、電荷抜け電圧低減効果の各特性をいずれもバランス良く発揮しており、ＰＤＰの保護層として特に優れた性能を有することが分かった。サンプル１０及び１１（実施例４及び５）は、放電ガスがＸｅ１００％の場合の放電開始電圧が３５０Ｖ以下と低く、電荷抜け電圧の低減に関しても良好であることに加えて、優れた放電遅れの抑制効果が備わっている。

(Experimental result)
From the results shown in Table 1, Samples 10 and 11 (Examples 4 and 5) corresponding to the configuration of the first embodiment are less effective in reducing the discharge start voltage and discharge than Samples 1 to 6 (Comparative Examples 1 to 6). Each of the characteristics of the delay time reduction effect and the charge leakage voltage reduction effect is exhibited in a well-balanced manner, and it has been found that the PDP protective layer has particularly excellent performance. Samples 10 and 11 (Examples 4 and 5) have a low discharge start voltage of 350 V or less when the discharge gas is Xe 100%, and are excellent in terms of reducing the charge leakage voltage, and also have excellent discharge delay. Has a suppression effect.

   The reason why these effects are highly balanced is that the high γ film formed in a predetermined oxidizing atmosphere as the surface layer plays a role of low voltage drive and charge retention, and the MgO fine particle group writes. It is conceivable that the characteristics of each of the separated films are synergistically exhibited, such as playing a role of releasing initial electrons necessary for discharging (ensuring initial electron emission characteristics).

In addition, MgO fine particles produced by a vapor phase synthesis method or a precursor firing method are dispersed on a protective layer made of SrO formed in an oxygen atmosphere with an oxygen partial pressure of 0.025 Pa or more by a spray method. Even in the case of the configuration described above, the same characteristics as those of Samples 10 and 11 (Examples 4 and 5) can be obtained.

   On the other hand, as described in the second embodiment, when the characteristics regarding the discharge delay time are not so much required, the reduction effect of the discharge start voltage and the charge release voltage are also obtained for samples 7 to 9 (Examples 1 to 3). It can be said that there is a clear advantage over the comparative example. In these samples 7 to 9 (Examples 1 to 3), even when a discharge gas having a discharge start voltage of Xe 100% is used, it is as low as 350 V or less, and has a good effect of reducing the charge leakage voltage. Accordingly, these two points have excellent characteristics comparable to those of the samples 10 and 11.

   In another experiment conducted by the inventors of the present application, in the high γ film such as Samples 5 and 7 to 9 (Comparative Example 5 and Examples 1 to 3), the discharge start voltage increases with the discharge time and the standing time. On the other hand, in the PDPs of Samples 6, 10, and 11 (Comparative Example 6, Examples 4 and 5), the result of suppressing the increase in the discharge start voltage was also obtained at the same time.

   In Samples 1 to 4 (Comparative Examples 1 to 4), it was found that when a discharge gas having a discharge start voltage of Xe 100% was used, the voltage was 400 V or higher, so that low voltage driving was not possible. In Samples 5 and 6 (Comparative Examples 5 and 6), the discharge starting voltage when using a discharge gas of 100% Xe is good at 240 V or less, but the charge retention effect is not obtained, so that sufficient charge loss is achieved. The voltage reduction effect cannot be obtained. Therefore, it was found that low voltage driving is not suitable for these.

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

   The PDP of the present invention can drive a high-definition image display at a low voltage, but can be used as a gas discharge panel technology in a television set, a computer display device, etc. in transportation facilities, public facilities, homes, etc. is there.

It is sectional drawing which shows the structure of PDP which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the relationship between each electrode and a driver. It is a figure which shows the drive waveform example of PDP. It is a figure for demonstrating each energy level of the surface layer of PDP of this Embodiment 1, and the protective layer of the conventional PDP. It is a figure which shows the characteristic of the protective layer which consists of an alkaline-earth metal oxide in a cathodoluminescence measurement. It is sectional drawing which shows the structure of PDP which concerns on Embodiment 2 of this invention. It is a graph which shows the relationship between the oxygen partial pressure at the time of film-forming, and a charge release voltage. It is a set figure which shows the structure of the conventional general PDP.

Explanation of symbols

1, 1x PDP
2 Front panel 3 Front panel glass 4 Sustain electrode 5 Scan electrode 6 Display electrode pair 7, 12 Dielectric layer 8, 8a Surface layer (high γ film)
9 Back panel
10 Back panel glass 11 Data (address) electrode 13 Bulkhead 14, 14R, 14G, 14B Phosphor layer 15 Discharge space 16 MgO fine particles

Claims (18)

The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
On the surface facing the discharge space of the first substrate, a surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide is disposed,
The surface layer is formed under an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or higher, and is a solid solution of at least two of calcium oxide, barium oxide, and strontium oxide. The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
A surface layer is disposed on the surface facing the discharge space of the first substrate,
The surface layer is formed by depositing at least one of calcium oxide, barium oxide, and strontium oxide, and has only an electron level band at a depth of 2 eV or more from the vacuum level. A plasma display panel, which is a solid solution of at least two of barium oxide and strontium oxide. The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
A surface layer is disposed on the surface facing the discharge space of the first substrate,
The surface layer is formed by depositing at least one of calcium oxide, barium oxide, and strontium oxide, and the existence of an electron level band at a depth of less than 2 eV from the vacuum level is excluded. A plasma display panel, which is a solid solution of at least two of calcium oxide, barium oxide, and strontium oxide. The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
On the surface facing the discharge space of the first substrate, a surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide is disposed,
When the surface layer is irradiated with light energy, the surface layer starts photoemission with an energy of 2 eV or more when the intensity of the light energy is changed in ascending order, and at least one of calcium oxide, barium oxide, and strontium oxide Plasma display panels that are two or more solid solutions. The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
On the surface facing the discharge space of the first substrate, a surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide is disposed,
Magnesium oxide fine particles are arranged on the surface of the surface layer on the discharge space side,
The surface layer is formed under an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or higher, and is a solid solution of at least two of calcium oxide, barium oxide, and strontium oxide. The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
On the surface facing the discharge space of the first substrate, a surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide is disposed,
Magnesium oxide fine particles are arranged on the surface of the surface layer on the discharge space side,
A plasma display panel, wherein the surface layer has only an electron level band at a depth of 2 eV or more from the vacuum level, and is a solid solution of at least two of calcium oxide, barium oxide, and strontium oxide. The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
On the surface facing the discharge space of the first substrate, a surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide is disposed,
Magnesium oxide fine particles are arranged on the surface of the surface layer on the discharge space side,
The surface layer is one in which the presence of an electron level band at a depth from the vacuum level of less than 2 eV is excluded, and is a solid solution of at least two of calcium oxide, barium oxide, and strontium oxide. panel. The first substrate on which the display electrodes are disposed is a plasma display panel sealed in a state facing the second substrate through a discharge space filled with a discharge gas,
On the surface facing the discharge space of the first substrate, a surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide is disposed,
Magnesium oxide fine particles are arranged on the surface of the surface layer on the discharge space side,
When the surface layer is irradiated with light energy, when the intensity of the light energy is changed in ascending order, the surface layer starts photoemission with an energy of 2 eV or more, and includes calcium oxide, barium oxide, and strontium oxide. A plasma display panel, which is a solid solution of at least two of the above. The plasma display panel according to claim 5, wherein the magnesium oxide fine particles are produced by a gas phase oxidation method. The plasma display panel according to claim 5, wherein the magnesium oxide fine particles are obtained by firing a magnesium oxide precursor at a temperature of 700 ° C or higher. The plasma display panel according to claim 2 or 4, wherein the surface layer is formed in an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or more. The plasma display panel according to any one of claims 1 to 11, wherein the surface layer is formed in an oxygen atmosphere having an oxygen partial pressure of 0.2 Pa or more. A surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide on the first substrate on which the display electrode is disposed is formed in an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or more. A surface layer forming step to be formed;
A sealing step of sealing the first substrate and the second substrate through the discharge space with the surface layer facing the discharge space;
In the surface layer forming step, the surface layer is formed of at least two kinds of solid solutions of calcium oxide, barium oxide, and strontium oxide. A method for manufacturing a plasma display panel. A surface layer formed by forming at least one of calcium oxide, barium oxide, and strontium oxide on the first substrate on which the display electrode is disposed is formed in an oxygen atmosphere having an oxygen partial pressure of 0.025 Pa or more. A surface layer forming step to be formed;
A magnesium oxide fine particle disposing step of disposing the magnesium oxide fine particles on the surface layer;
A sealing step of sealing the first substrate and the second substrate with the surface layer facing the discharge space through the discharge space;
In the surface layer forming step, the surface layer is formed of at least two kinds of solid solutions of calcium oxide, barium oxide, and strontium oxide. A method for manufacturing a plasma display panel. The method for manufacturing a plasma display panel according to claim 14, wherein the magnesium oxide fine particle disposing step uses magnesium oxide fine particles produced by a gas phase oxidation method. The method for manufacturing a plasma display panel according to claim 14, wherein the magnesium oxide fine particle disposing step uses magnesium oxide fine particles prepared by firing a magnesium oxide precursor at a temperature of 700 ° C. or more. The method for manufacturing a plasma display panel according to claim 13 or 14, wherein in the surface layer forming step, the surface layer is formed by one or more of a vapor deposition method, a sputtering method, and an ion plating method. The method for manufacturing a plasma display panel according to any one of claims 13 to 17, wherein the surface layer is formed in an oxygen atmosphere having an oxygen partial pressure of 0.2 Pa or more.

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