JP2011198611A - Method for manufacturing plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for achieving a plasma display panel having high-brightness display performance and capable of low-voltage driving.SOLUTION: A method for manufacturing a plasma display panel having: a front panel where an electrode A, a dielectric layer A and a protection layer are formed on a substrate A; and a rear panel where an electrode B, a dielectric layer B, a partition and a fluorescent layer is formed on a substrate B includes the steps of: (i) heating the front panel under vacuum; and (ii) cooling the front panel after the heating. In step (ii), inert gas starts to be supplied in a temperature range between 250°C and the highest temperature in step (i), to cool the front panel in the inert atmosphere.

Description

  The present invention relates to a method for manufacturing a plasma display panel. More specifically, the present invention relates to a method for manufacturing a plasma display panel used for image display of a television or a computer.

  A plasma display panel (hereinafter referred to as a PDP) can realize a high definition and a large screen, and thus a 100-inch class television or the like has been commercialized. In recent years, PDP has been applied to high-definition televisions that have more than twice the number of scanning lines compared to the conventional NTSC system. In response to energy problems, efforts to further reduce power consumption and environmental issues There is also a growing demand for PDPs that do not contain lead components in consideration of the above.

  A PDP basically includes a front plate and a back plate. The front plate is a display electrode composed of a glass substrate of sodium borosilicate glass manufactured by a float method or the like, a striped transparent electrode formed on one main surface of the glass substrate, and a bus electrode; A dielectric layer that covers the display electrodes and functions as a capacitor, and a protective layer made of magnesium oxide (MgO) formed on the dielectric layer.

  On the other hand, the back plate is a glass substrate, stripe-shaped address electrodes formed on one main surface thereof, a base dielectric layer covering the address electrodes, a partition formed on the base dielectric layer, The phosphor layer is formed between the barrier ribs and emits red, green and blue light.

  The front plate and the back plate are hermetically sealed with their electrode forming surfaces facing each other, and a discharge gas of neon (Ne) -xenon (Xe) is sealed at a pressure of about 400 Torr to 600 Torr in a discharge space partitioned by a partition wall. Has been. In a PDP, a video signal voltage is selectively applied to a display electrode to cause discharge, and ultraviolet rays generated by the discharge excite each color phosphor layer to emit red, green, and blue light, thereby realizing color image display. is doing.

  In addition, such a PDP driving method includes an initialization period in which wall charges are adjusted so that writing is easy, a writing period in which writing discharge is performed according to an input image signal, and a discharge space in which writing is performed. A driving method having a sustain period in which display is performed by generating a sustain discharge is generally used. A period (subfield) obtained by combining these periods is repeated a plurality of times within a period (one field) corresponding to one frame of an image, thereby performing PDP gradation display.

  In such a PDP, the role of the protective layer formed on the dielectric layer of the front plate is to protect the dielectric layer from ion bombardment due to discharge, and to release initial electrons for generating address discharge, etc. It is. Protecting the dielectric layer from ion bombardment plays an important role in preventing an increase in discharge voltage, while emitting initial electrons to generate address discharge causes an address that causes image flickering. This is an important role in preventing discharge mistakes.

  In order to increase the number of initial electrons emitted from the protective layer and reduce image flickering, for example, examples of adding impurities to the MgO protective layer and examples of forming MgO particles on the MgO protective layer are disclosed. (See, for example, Patent Documents 1, 2, 3, 4 and 5).

  The operating voltage of the PDP depends on the secondary electron emission coefficient of the protective layer. Therefore, it is conceivable to reduce the operating voltage by using an alkaline earth metal oxide (for example, calcium oxide, strontium oxide, barium oxide, etc.) having a work function smaller than that of magnesium oxide as a protective layer. However, such alkaline earth metal oxides are highly hygroscopic, and there is concern that they will react with moisture in the atmosphere after the protective layer is formed and change to hydroxides, resulting in unstable discharge characteristics. The Alternatively, there is a concern that the operating voltage may not be lowered due to transformation into carbonate. Therefore, a method of continuously performing the process from the protective layer forming process to the sealing process in a dry atmosphere (see, for example, Patent Document 6), or the process from the protective layer forming process to the sealing process is continued in a vacuum atmosphere. And the like (see, for example, Patent Document 7). In addition, a method for moving the adsorbed gas to the adsorbent (for example, see Patent Document 8), a method for performing an activation process such as vacuum baking (for example, see Patent Document 9), and the like have been proposed.

JP 2002-260535 A JP 11-339665 A JP 2006-59779 A JP-A-8-236028 JP-A-10-334809 JP 2002-216620 A JP 2002-231129 A JP 2002-352703 A JP 2004-134095 A

  In light of the demands of PDPs such as high definition of TV, low cost, low power consumption, high brightness full HD (high definition) (1920 x 1080 pixels: progressive display) in the market, Control of electron emission characteristics has become very important. This is because the electron emission characteristics from the protective layer determine the image quality of the PDP.

  In this regard, in order to display a high-definition image, the number of pixels to be written increases even though the time of one field is constant. Therefore, a pulse applied to the address electrode during the writing period in the subfield. It is necessary to reduce the width of the. However, there is a time lag called “discharge delay” from the rise of the voltage pulse to the occurrence of discharge in the discharge space, so if the pulse width is narrowed, the probability that the discharge can be completed within the writing period is low. End up. As a result, lighting failure occurs, and the problem of deterioration in image quality performance such as flickering occurs.

  As described above, in order to advance the high definition and low power consumption of the PDP, it is necessary to simultaneously realize that the discharge voltage is not increased and that the image quality is improved by reducing defective lighting. There is a problem.

  Here, the above-mentioned “method of continuously performing the protective layer formation step after the protective layer formation step to the sealing step in a dry atmosphere in order to prevent the protective layer from being hydroxylated or carbonated” does not form an altered layer on the surface of the protective layer. However, the dry air contains a certain amount of moisture and carbon dioxide, and unless the content is sufficiently small, an altered layer is formed by exposure for several tens of minutes to several hours. (For example, 0.1% in dry air having a dew point of −20 ° C., 0.013% in dry air having a dew point of −40 ° C., and 0.0011% (11 ppm in dry air having a dew point of −60 ° C.) ) Contains water). In the manufacturing process of PDP, since there is generally a process inventory of several hours or more from the protective layer forming process to the sealing process, even if dry air with a very low dew point (−60 ° C. or less) is used. It can be said that the formation of an altered layer is inevitable. In addition, the above-described “method of continuously performing the process from the protective layer forming step to the sealing step in a vacuum atmosphere” is extremely difficult to realize because the configuration of the transport system and the sealing device is extremely complicated. Moreover, it is necessary to always keep a vast space in a vacuum, which requires a great deal of cost. Furthermore, since the above-described “method of moving the adsorbed gas to the adsorbent” is performed at atmospheric pressure, it is considered that activation as high as the vacuum baking described below cannot be expected. And about the "activation process by vacuum baking", a hydroxide layer and a carbonation layer can be removed and a very clean protective layer can be obtained. However, as a result of intensive studies by the present inventors, the method of performing the activation treatment by vacuum baking is a method in which a large amount of hydrocarbon-based gas is adsorbed on the protective layer in the process of cooling the front plate in vacuum after the activation treatment. As a result, it has been found that the panel quality is deteriorated such that the fluorescent luminance is lowered in the panel after sealing.

  The present invention has been made in view of the above circumstances. That is, an object of the present invention is to provide a method for realizing a PDP having high luminance display performance and capable of being driven at a low voltage.

In order to solve the above problems, in the present invention, a front plate in which an electrode A, a dielectric layer A, and a protective layer are formed on a substrate A, and an electrode B, a dielectric layer B, a barrier rib, and a fluorescent light on a substrate B are provided. A plasma display panel manufacturing method comprising a back plate on which a body layer is formed,
Prior to subjecting the front plate and the rear plate to the sealing treatment, (i) heating the front plate under vacuum, and (ii) cooling the front plate after the heating,
In the step (ii), the supply of the inert gas is started in the temperature range of not more than the maximum temperature at the time of heating in the step (i) to 250 ° C. or more, and the front plate is cooled in an inert gas atmosphere. A method for manufacturing a plasma display panel is provided.

  One feature of the present invention is that when the front plate heated under vacuum is cooled, the front plate is cooled while being exposed to an inert gas from a temperature range of not more than the maximum temperature during heating to 250 ° C. or more. . Here, the “maximum temperature during heating” in the present invention is, for example, a temperature of 450 ° C. or more and 560 ° C. or less.

  In this specification, the “front plate” refers to a panel substrate on the surface side as viewed from the person viewing the image, and substantially refers to the panel substrate on the side where the phosphor layer and the partition wall are not present. (In other words, it can be said that the “front plate” is the panel substrate disposed opposite to the “back plate” in which the phosphor layers and the barrier ribs are present).

  Further, in this specification, “starting the supply of inert gas” means that the inert gas is supplied so that the front plate is exposed to the inert gas atmosphere. In other words, “start the inert gas supply” means to start supplying the inert gas to the substantially closed space where the front plate is disposed. For example, when the front plate is heated in the vacuum atmosphere in the chamber in step (i), this means that an inert gas starts to be supplied into the chamber.

  In a preferred embodiment, the supply of the inert gas is started in a temperature range of not more than the maximum temperature during heating in step (i) to not less than 300 ° C. That is, in the step (ii), the inert gas supply is started in the temperature range of the maximum temperature or lower to 300 ° C. or higher at the time of heating in the vacuum in the step (i). Cool under atmosphere.

  In another preferred embodiment, the front plate is cooled to a temperature of 100 ° C. or lower when performing the step (ii). That is, the front plate heated under vacuum is cooled while being exposed to an inert gas, but finally the front plate is cooled to 100 ° C. or lower.

  In still another preferred embodiment, the metal oxide is composed of at least two oxides selected from magnesium oxide, calcium oxide, strontium oxide and barium oxide. A protective layer for the front plate is formed from a metal oxide having a peak between the minimum diffraction angle and the maximum diffraction angle generated from a single oxide constituting the object.

  Incidentally, nitrogen gas or rare gas is preferable as the inert gas used in the production method of the present invention.

Moreover, in the manufacturing method of this invention, it is preferable to perform a cleaning process to a protective layer, after implementing said process (i) and (ii). Specifically, it is preferable to carry out the following steps (a) to (c):
(A) A step of forming a glass frit sealing member by providing a glass frit material to the peripheral region of the substrate A or the substrate B;
(B) a step of arranging the front plate and the back plate so as to sandwich the glass frit sealing member; and (c) a temperature equal to or higher than the softening point of the sealing member so that the front plate and the back plate are sealed. Between the start of the heat treatment and the softening point of the sealing member (or in some cases, the temperature above the softening point). A process of flowing a cleaning gas (for example, nitrogen gas or rare gas) between the face plate and the back plate.

  ADVANTAGE OF THE INVENTION According to this invention, the secondary electron emission characteristic of a protective layer can be improved, and PDP excellent in the display performance which can be driven by high-intensity and low voltage is realizable.

  In other words, due to the feature of “when cooling the front plate heated under vacuum, the front plate is cooled while being exposed to an inert gas from a temperature range of not more than the maximum temperature of the heating to 250 ° C. or more” It is possible to obtain a front plate in which hydrocarbon gas adsorption in the protective layer is effectively reduced. Further, due to such a cooling process, the effect of removing the deteriorated layer of the front plate protective layer is further improved during the cleaning process when sealing the panel. Therefore, a preferable protective layer material can be obtained in terms of the secondary electron emission coefficient and the like, and a PDP having high luminance display performance and capable of being driven at a low voltage can be realized.

  In particular, in the present invention, since the cooling process or the cleaning process is performed on the protective layer as described above, it should be noted that the protective layer can be formed from components particularly suitable for the panel characteristics. “A component particularly suitable for panel characteristics” is a metal oxide composed of at least two oxides selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide, and has a specific orientation in X-ray diffraction analysis. It refers to a metal oxide having a peak between the minimum diffraction angle and the maximum diffraction angle generated from the simple substance of the oxide constituting the metal oxide on the surface. Although such a metal oxide is preferable because the discharge start voltage of the panel is further reduced, the discharge delay is reduced, and the discharge is particularly stable, the reactivity with water and an impurity gas such as carbon dioxide is particularly high. In other words, the use of such a metal oxide as a protective layer component generally means that the protective layer only reacts with water and carbon dioxide to cause deterioration of discharge characteristics. In this respect, in the present invention, as described above, the “front plate cooling process” and the “cleaning process at the time of panel sealing” are preferably performed, so that such inconvenience can be avoided and desired protection can be achieved. Layer components can be used positively.

The perspective sectional view which showed the manufacturing method of the present invention notionally The figure which showed the structure of PDP typically (FIG. 2 (a): The perspective view which showed the schematic structure of PDP typically, FIG.2 (b): The sectional view which showed the PDP front plate typically) Sectional view of baking chamber in vacuum baking equipment The graph which shows an example of the temperature and pressure trend accompanying implementation of process (i) and (ii) of this invention The top view which shows roughly the whole structure of a vacuum baking apparatus The figure which showed the mode at the time of sealing processing typically Graph showing the dependence of inert gas supply start temperature on hydrocarbon gas adsorption Graph showing the dependence of the inert gas supply start temperature on the amount of moisture adsorbed on the activation site The figure which shows the X-ray-diffraction result in the base film of a PDP protective layer The figure which shows the X-ray-diffraction result in the base film of the other structure of a PDP protective layer Enlarged view for explaining aggregated particles of PDP protective layer The figure which shows the relationship between the discharge delay of PDP and the calcium (Ca) density | concentration in a protective layer The figure which shows the result of having investigated about the electron emission performance and charge retention performance of PDP Characteristic diagram showing the relationship between the particle size of crystal grains used in PDP and electron emission characteristics

  Hereinafter, a method for manufacturing a plasma display panel according to the present invention will be described in detail with reference to the drawings. It should be noted that the various elements shown in the drawings are merely schematically shown for understanding of the present invention, and the dimensional ratio, appearance, and the like may differ from the actual ones.

[ Configuration of plasma display panel ]
First, a plasma display panel finally obtained through the manufacturing method of the present invention will be briefly described. FIG. 2A schematically shows the structure of the PDP in a sectional perspective view, and FIG. 2B schematically shows a sectional view of the front plate of the PDP.

  As shown in FIG. 2 (a), the PDP (100) of the present invention has a structure in which an electrode A (11), a dielectric layer A (15), and a protective layer (16) are provided on a substrate A (10). The front plate (1) ”and the back plate (on which the electrode B (21), the dielectric layer B (22), the partition wall (23), and the phosphor layer (25) are provided on the substrate B (20)). 2) ".

  As shown in the figure, the front plate (1) is provided with the electrode A (11) on the substrate A (10), and the dielectric layer A (15) is disposed on the substrate A (10) so as to cover the electrode A (11). In addition, a protective layer (16) is provided on the dielectric layer A (15). In the back plate (2), an electrode B (21) is provided on the substrate B (20), and a dielectric layer B (22) is provided on the substrate B (20) so as to cover the electrode B (21). A partition wall (23) and a phosphor layer (25) are provided on the body layer B (22). The front plate (1) and the back plate (2) are arranged to face each other so that the protective layer (16) and the phosphor layer (25) face each other. The peripheral portions of the front plate (1) and the back plate (2) are hermetically sealed by a sealing member made of, for example, a low melting point frit glass material (not shown). A discharge space (30) formed between the front plate (1) and the back plate (2) is filled with a discharge gas (such as helium, neon, or xenon) at a pressure of about 20 kPa to 80 kPa, for example.

More specifically, the PDP (100) of the present invention will be described. As described above, the front plate (1) of the PDP (100) of the present invention includes the substrate A (10), the electrode A (11), the dielectric layer A (15) and the protective layer (16). . The substrate A (10) is a transparent and insulating substrate (having a thickness of about 1.0 mm or more and about 3 mm or less). Examples of the substrate A (10) include a float glass substrate manufactured by a float process or the like, and a soda lime glass substrate or a borosilicate glass substrate. A plurality of electrodes A (11) are arranged in parallel in the form of stripes on the substrate A (10), and are, for example, display electrodes including scan electrodes (12) and sustain electrodes (13). In this case, the scanning electrode (12) and the sustaining electrode (13) are respectively “transparent electrodes (12a, 13a) which are transparent conductive films made of indium oxide (ITO) or tin oxide (SnO ₂ )” and the like. It is comprised from "the bus electrode (12b, 13b) which has silver as a main component" formed on the transparent electrode (refer FIG.2 (b)). The transparent electrodes (12a, 13a) mainly function as electrodes that transmit visible light generated in the phosphor layer, while the bus electrodes (12b, 13b) provide conductivity in the longitudinal direction of the transparent electrodes. Mainly functions as an electrode. The thickness of the transparent electrodes (12a, 13a) is preferably about 50 nm to about 500 nm. The thickness of the bus electrodes (12b, 13b) is preferably about 1 μm or more and about 20 μm or less. As shown in FIG. 2A, a black stripe (14) (light-shielding layer) can also be patterned on the substrate A (10).

  The dielectric layer A (15) is provided so as to cover the electrode A (11) formed on the surface of the substrate A (10). The dielectric layer A (15) is a film made of a glass composition obtained by applying and heat-treating a dielectric raw material paste mainly composed of a glass component and a vehicle component (= a component containing a binder resin and an organic solvent). On the dielectric layer A (15), a protective layer (16) made of, for example, magnesium oxide (MgO) is formed (thickness is about 0.5 μm or more and about 1.5 μm or less).

  On the other hand, as described above, the back plate (2) of the PDP of the present invention includes the substrate B (20), the electrode B (21), the dielectric layer B (22), the partition wall (23), and the phosphor layer (25). It has. The substrate B (20) is preferably a transparent and insulating substrate (thickness is, for example, not less than about 1.0 mm and not more than about 3 mm), for example, a float glass substrate manufactured by a float method or the like. In addition, a soda lime glass substrate, a borosilicate glass substrate, various ceramic substrates, and the like can be given. The electrode B (21) is an electrode (thickness is about 1 μm or more and about 10 μm or less) made mainly of silver and formed in stripes on the substrate B (20). Data electrode). The address electrode mainly has a function of selectively discharging each discharge cell.

  The dielectric layer B (22) is generally called a base dielectric layer, and is provided so as to cover the electrode B (21) formed on the surface of the substrate B (20). The dielectric layer B (22) is a film made of a glass composition obtained by applying and heat-treating a dielectric material paste mainly composed of a glass component and a vehicle component (= a component containing a binder resin and an organic solvent). The thickness of the dielectric layer B (22) is, for example, not less than about 5 μm and not more than about 50 μm. On the dielectric layer B (22), a phosphor layer (25) mainly composed of a phosphor material is formed (the thickness is, for example, about 5 μm or more and about 20 μm or less). The phosphor layer (25) mainly has a function of converting ultraviolet rays emitted by the discharge into visible light. The phosphor layer (25) has phosphor layers emitting red, green and blue as structural units, and each is separated by a partition wall (23). The barrier ribs (23) are formed on the dielectric layer B (22) in a stripe shape or in a grid pattern for the purpose of partitioning the discharge space for each address electrode (21). The partition wall (23) is formed from a paste raw material including a glass component, a vehicle component, a filler, and the like.

  In the PDP (100) of the present invention, the front plate (1) and the back plate (2) are arranged so that the display electrode (11) of the front plate (1) and the address electrode (21) of the back plate (2) are orthogonal to each other. Are arranged opposite to each other across the discharge space (30). In such a PDP (100), the discharge space (30) partitioned by the partition wall (23) and intersecting the address electrode (21) and the display electrode (11) functions as a discharge cell (32). In other words, the discharge cells arranged in a matrix form an image display area. Accordingly, the discharge gas is discharged by selectively applying the video signal voltage from the external drive circuit to the display electrode (11), and the phosphor layers of the respective colors are excited by the ultraviolet rays generated by the discharge, thereby red, green, and blue. When visible light is generated, color image display is realized.

[ General manufacturing method of PDP ]
Next, a general method for manufacturing a PDP will be briefly described. Unless otherwise stated, the PDP according to the present invention can be obtained based on a general PDP manufacturing method in principle. Unless otherwise specified, raw materials (raw material pastes) / constituent materials of various constituent members may also be those conventionally used in general PDP manufacturing methods.

First, on the substrate A (10) which is a glass substrate, the display electrode (11) composed of the scan electrode (12) and the sustain electrode (13) is formed as the electrode A. The transparent electrodes (12a, 13a) and the bus electrodes (12b, 13b) of the scan electrode (12) and the sustain electrode (13) can be patterned using a photolithography method that exposes and develops. The transparent electrodes (12a, 13a) can be formed by using a thin film process or the like, and the bus electrodes (12b, 13b) are obtained by drying (about 100 to 200 ° C.) and baking (about 400 to 600 ° C.) a paste containing a silver (Ag) material. ). Further, when forming the electrode A, a light shielding layer (14) may also be formed. After the raw material paste containing the black pigment is screen-printed or the raw material containing the black pigment is provided on the entire surface of the glass substrate, exposure / It can be formed by patterning using a photolithography method for development and baking. Next, a glass component (material formed from SiO ₂ , B ₂ O _3, etc.) and a vehicle on the substrate A (10) so as to cover the scan electrode (12), the sustain electrode (13), and the light shielding layer (14). A dielectric material paste mainly composed of components is applied by a die coating method or a printing method to form a dielectric paste layer. After application, if left for a predetermined time, the surface of the applied dielectric paste is leveled to form a flat surface. Thereafter, when the dielectric paste layer is fired, a dielectric layer A (15) is formed. After forming the dielectric layer A (15), a protective film (16) is formed on the dielectric layer A (15). The protective film (16) can be generally formed by using a vacuum deposition method, a CVD method, a sputtering method, or the like.

  Through the above steps, electrodes A (scanning electrode (12) and sustaining electrode (13)), dielectric layer A (15) and protective layer (16), which are predetermined constituent members, are formed on substrate A (10). The front plate (1) is completed.

On the other hand, the back plate (2) is formed as follows. First, the address electrode (21) is formed as the electrode B on the substrate B (20) which is a glass substrate. Specifically, a method of screen printing a paste containing a silver (Ag) material, a method of patterning using a photolithography method in which a metal film mainly composed of silver is formed on the entire surface, and then exposed and developed are used. An address electrode (21) is formed by forming a precursor layer and firing it at a desired temperature (eg, about 400 to about 600 ° C.). This “address electrode” may be formed by patterning a chrome / copper / chromium three-layer thin film coated with a photoresist by photolithography and wet etching. Next, a dielectric layer B (22) serving as a base dielectric layer is formed on the substrate B (20) on which the address electrodes (21) are formed. First, a “dielectric material paste mainly composed of a glass component (a material formed from SiO ₂ , B ₂ O ₃ or the like) and a vehicle component” is applied by a die coating method or the like to form a dielectric paste layer. And dielectric layer B (22) can be formed by baking this dielectric paste layer. Next, a partition wall (23) is formed. Specifically, a partition wall forming raw material paste is applied onto the dielectric layer B (22) and patterned into a predetermined shape to form a partition wall material layer, which is then fired to form a partition wall ( 23). For example, by a photolithography method in which a raw material paste mainly composed of a low-melting glass material, a vehicle component and a filler is applied by a die coating method or a printing method, dried at about 100 ° C. to 200 ° C., and then exposed and developed. The partition wall (23) is formed by patterning and then baking at about 400 ° C. to about 600 ° C. The partition wall (23) can also be formed by using a sandblast method, an etching method, a molding method, or the like. Next, a phosphor layer (25) is formed. A phosphor raw material paste containing a phosphor material is applied on the dielectric layer B (22) between the adjacent barrier ribs (23) and on the side surfaces of the barrier ribs (23), and baked to form the phosphor layer (25). . More specifically, the phosphor paste is prepared by applying a raw material paste mainly composed of phosphor powder and a vehicle component by a die coating method, a printing method, a dispensing method, an ink jet method or the like, and then drying at about 100 ° C. A layer (25) is formed.

  Through the above steps, the electrode B (address electrode (21)), the dielectric layer B (22), the partition wall (23), and the phosphor layer (25), which are predetermined constituent members, are formed on the substrate B (20). The back plate (2) is completed.

  In this way, the front plate (1) and the back plate (2) provided with predetermined constituent members are arranged to face each other so that the display electrodes (11) and the address electrodes (21) are orthogonal to each other. Next, the periphery of the front plate (1) and the back plate (2) is sealed with a glass frit, and a discharge gas (helium, neon, xenon, etc.) is sealed in the discharge space (30) to be formed. 100) is completed.

[ Production method of the present invention ]
The present invention is particularly characterized in the manufacturing process from the formation of the front plate to the panel sealing, among the above-mentioned PDP manufacturing processes.

  In the manufacturing method of the present invention, first, a front plate in which an electrode A, a dielectric layer A, and a protective layer are formed on a substrate A is prepared. Since the preparation of the front plate has been described in the above-mentioned [General manufacturing method of PDP], description thereof is omitted to avoid duplication. Incidentally, the protective layer is preferably formed from a metal oxide composed of at least two oxides selected from magnesium oxide, calcium oxide, strontium oxide and barium oxide. In the present invention, such a metal oxide has a peak between the minimum diffraction angle and the maximum diffraction angle generated from the simple substance of the oxide constituting the metal oxide in a specific orientation plane in X-ray diffraction analysis. Note that it is particularly preferred. When such a protective layer component is used, the discharge start voltage of the panel is lowered, the discharge delay is reduced, and the discharge is stabilized. Since the metal oxide has high reactivity with impurity gases such as water and carbon dioxide, the metal oxide is generally used as a protective layer component. It can be said that it may react with carbon dioxide and cause deterioration of discharge characteristics. In this regard, in the present invention, as described later, “the heat treatment under vacuum of the front plate / cooling treatment under an inert gas atmosphere” and “cleaning treatment at the time of panel sealing” are performed. Such an inconvenient reaction is avoided, and the metal oxide can be positively used.

  In the present invention, the prepared front plate is placed opposite to the back plate and subjected to a sealing treatment. Prior to the sealing treatment, the front plate is heated in a vacuum atmosphere and subsequently cooled. Processing is performed (hereinafter, heat treatment in a vacuum atmosphere is also referred to as “vacuum baking”).

Referring to FIG. 1, the present invention performs the following steps (i) and (ii):
Step (i) : After preparing the front plate in the chamber, the atmosphere in the chamber is evacuated and the front plate is heated (see FIG. 1 (a)).
Step (ii) : The heating of the front plate is finished, and cooling of the front plate is started in the chamber. And supply of an inert gas is started in the temperature range below the maximum temperature at the time of heating-250 degreeC or more, and a front board is cooled in inert gas atmosphere (refer FIG.1 (b)).

  In the present invention, “under a vacuum atmosphere” substantially means an atmospheric pressure reduced from atmospheric pressure. For example, a pressure of about 0.00001 Pa to 0.1 Pa corresponds to the “vacuum” of the present invention with respect to the internal atmosphere of the chamber in which the front plate is charged. Assuming an embodiment using a vacuum baking apparatus (40) as shown in FIG. 3, the inside atmosphere of the chamber (41) is made "vacuum" by exhausting the inside of the baking chamber (41) by the exhaust pump (42). it can. As the exhaust pump (42), it is preferable to use a pump having a high exhaust speed such as a cryopump or a turbo molecular pump.

  The heating of the front plate in a vacuum atmosphere is intended to desorb impurity gas components from the protective layer. Therefore, the maximum temperature during the heat treatment is not limited in principle as long as the impurity gas component is desorbed from the protective layer. However, in consideration of the most effective desorption and the influence on other components, the maximum temperature during the heat treatment is preferably 450 ° C. or higher and 560 ° C. or lower. If the maximum temperature during heat treatment is less than 450 ° C., “desorption of impurity gas components” due to vacuum baking may be insufficient. On the other hand, if the maximum temperature during heat treatment exceeds 560 ° C., the dielectric layer softens and melts. Because it can.

  In step (i) of the present invention, the front plate (1) is heated in the chamber (41). As the heating means, as shown in FIG. 3, a “lamp (43)” and a “reflector (44)” installed in the chamber (41) may be used. In such a case, the heat generated from the lamp due to the electrode supply to the lamp (43) is used as a heat source, and this heat is efficiently transmitted to the front plate (1) by the reflector (44). .

  In the heat treatment of step (i), as described above, the front plate is preferably heated to a maximum temperature of 450 ° C. to 560 ° C., but the maximum temperature during this heat treatment can be maintained for about 1 to 30 minutes. preferable.

After the heat treatment, the front plate is cooled as step (ii). In the mode shown in FIG. 3, first, the power supply of the lamp (43) is stopped. Thereby, the temperature of a front plate (1) falls gradually. In the present invention, at the time of such cooling, the supply of the inert gas is started in a temperature range of the maximum temperature or lower to 250 ° C. or higher during heating, and the front plate is cooled in an inert gas atmosphere. This is because a front plate from which the impurity gas component is effectively removed from the protective layer can be obtained. Of the impurity gas components desorbed from the protective layer by the heat treatment, hydrocarbon gas components (for example, CH ₄ gas and C ₂ H ₆ gas) can be adsorbed to the protective layer during the cooling process. However, in the present invention, the front plate is cooled in an inert gas atmosphere from the temperature range of the maximum temperature or lower to 250 ° C. or higher during heating, and as a result, the adsorption of hydrocarbon gas components during the cooling process is effective. (The effects of the present invention will be described later).

  The supply of the inert gas performed in the cooling process is performed from a predetermined temperature in a temperature range of not more than the maximum temperature during heating to not less than 250 ° C. That is, the inert gas starts to be supplied into the chamber 41 before the cooling is started and the temperature is lowered to 250 ° C., and then the supply is continued. In the vacuum baking apparatus (40) shown in FIG. 3, an inert gas is supplied into the baking chamber (41) from the flow controller (45) through the valve (46). The inert gas to be used is not particularly limited, but may be, for example, nitrogen gas or a rare gas (He, Ne, Ar, Xe, etc.). There is no restriction | limiting in particular also about the temperature of the inert gas supplied, For example, it may be about 2 degreeC-35 degreeC, for example, it is normal temperature (about 25 degreeC will illustrate).

  In a particularly more preferable aspect, the supply of the inert gas is started before the temperature of the front plate drops to 300 ° C. That is, the supply of the inert gas is started in the temperature range of the maximum temperature or lower to 300 ° C. or higher during heating, thereby cooling the front plate while exposing it to the inert gas atmosphere. In such an embodiment, “re-adsorption of hydrocarbon gas components to the protective layer during the cooling process” can be more effectively prevented (this effect will also be described later).

In addition, the chamber internal pressure increases by continuing the inert gas supply. Finally, the internal pressure of the chamber becomes substantially the same as the atmospheric pressure. When the atmospheric pressure in the chamber reaches about atmospheric pressure and the cooling temperature of the front plate reaches a desired temperature, the front plate is taken out from the chamber and subjected to a sealing process. When taking out from the chamber, the front plate is preferably cooled to 100 ° C. or lower. This is because alteration layer formation (that is, hydroxylation or carbonation) on the surface of the protective layer that may occur when exposed to H ₂ O or CO ₂ can be effectively reduced or prevented.

  FIG. 4 schematically shows an example of the change over time in temperature and pressure associated with the implementation of steps (i) and (ii) of the present invention. Referring to FIG. 4, “When the front plate is heat-treated in a vacuum atmosphere and then cooled, the supply of the inert gas is started in the temperature range from the highest temperature during heating to 250 ° C. or higher. The characteristic process of the present invention such as “cooling under an inert gas atmosphere” will be understood. The cooling mechanism in the step (ii) of the present invention will be described. Between the maximum heating temperature and the inert gas supply start temperature, the front plate is cooled mainly by radiation. That is, heat is transferred from the front plate to the reflecting plate by radiation. Since the front plate is held hollow by a support mechanism (not shown), the front plate is cooled by heat conduction through the support mechanism, but its influence is negligibly small. In addition, since the air is evacuated, the heat transfer through the gas can be almost ignored. On the other hand, after the start of the supply of the inert gas, the front plate is cooled by heat transfer via the inert gas in addition to the above radiation. Since the influence cannot be ignored, the cooling rate is slightly improved with the inert gas supply start temperature as a boundary.

  FIG. 5 schematically shows the overall configuration of a vacuum baking apparatus that can be used in the production method of the present invention. In the illustrated vacuum baking apparatus aspect, the load lock chamber (49) is provided in a state where it can communicate with the baking chamber (41) via the gate (48). With reference to FIG. 5 and FIG. 3 described above, the “process mode after forming the protective layer of the front plate and before the sealing process” will be described over time.

  First, the front plate (1) on which the protective layer is formed is placed on a tray (not shown) placed in the load lock chamber (49). Next, using a transport system (not shown), the front plate (1) is transported to the baking chamber (41) through the gate (48) together with the tray. After the transfer, the gate (48) is closed, and the inside of the baking chamber (41) is evacuated using the pump (42). The internal atmosphere of the baking chamber is depressurized by the exhaust. When the atmosphere inside the chamber reaches a predetermined vacuum pressure (for example, 0.001 Pa or less), electric power is supplied to the lamp (43) provided in the baking chamber (41) to start heating the front plate (1). The temperature of the front plate (1) begins to rise due to heating. Finally, the front plate is heated until a certain predetermined temperature (for example, about 500 ° C.) is reached, and the maximum temperature reached for several minutes (for example, about 2 minutes). Subsequently, the lamp (43) is turned off and cooling of the front plate (1) is started. In this cooling process, the temperature of the front plate gradually decreases. Then, the supply of the inert gas is started until the temperature of the front plate (1) falls below 250 ° C. Specifically, an inert gas is supplied from the flow rate controller (45) through the valve (46) into the baking chamber (41). Thereby, the front plate can be cooled in an inert gas atmosphere. By supplying the inert gas, the atmospheric pressure in the baking chamber (41) gradually increases, and finally reaches a pressure approximately equal to the atmospheric pressure. And cooling of a front plate is continued until the temperature of a front plate reaches 100 degrees C or less. When the cooling of the front plate (1) is completed, the front plate (1) is transferred to the load lock chamber (49) together with the tray. Then, the transported front plate (1) is taken out from the load lock chamber (49) and used for the sealing process in the next step.

(About sealing process)
After the front plate is subjected to the above heat treatment / cooling treatment, that is, after the front plate is taken out from the load lock chamber, the sealing treatment is performed. That is, the sealing process is performed by arranging the front plate and the back plate to face each other through the glass frit sealing member. The back plate to be disposed opposite to the front plate is a back plate in which an electrode B, a dielectric layer B, a partition wall, and a phosphor layer are formed on a substrate B. Since the preparation of the back plate has been described in the above-mentioned [General manufacturing method of PDP], description thereof is omitted to avoid duplication.

  The sealing process and the cleaning process that can be performed along with the sealing process will be specifically described with reference to FIG. First, the front plate (1) and the back plate (2) are aligned in the alignment apparatus, and the two substrates are brought into close contact with each other via the glass frit sealing member (86). Next, the tip tube (55) is attached in accordance with the through hole (29) provided in the back plate (2). Next, the two substrates are sealed in a sealed exhaust furnace while a cleaning gas (for example, nitrogen gas) is blown from the tip tube (55) into the space between the front plate (1) and the back plate (2). Heat. By heating the front plate (1) and the back plate (2) in the sealing exhaust furnace while blowing the cleaning gas, the glass frit sealing member (86) is melted and the two substrates are sealed. The If the sealing process is carried out without blowing the cleaning gas, the protective layer may be hydroxylated and carbonated due to the influence of moisture and carbon dioxide in the air. The starting voltage increases. In order to avoid this, nitrogen gas or the like is blown into the space between the front plate and the back plate as a cleaning process in the sealing step. Such blowing of the cleaning gas is stopped when the substrate temperature reaches the softening point of the glass frit sealing member. That is, when the glass frit sealing member is softened and the periphery of the front plate and the back plate is completely sealed, the blowing of the cleaning gas is stopped.

  A note about the cleaning gas. The cleaning gas used is preferably a gas inert to the protective layer. For example, nitrogen gas can be mentioned. Further, a rare gas such as helium, argon, neon, or xenon may be used. Incidentally, it is desirable that the cleaning gas to be blown in is a gas containing almost no water vapor. For example, the moisture concentration of the cleaning gas to be blown is preferably 1 ppm or less. The “gas moisture concentration (ppm)” here is the volume fraction of moisture (water vapor) in the total volume of gas (standard state at 0 ° C. and 1 atm) expressed in parts per million. It refers to the value obtained by measuring with a dew point meter. Since nitrogen gas is relatively expensive, a cost-effective PDP manufacturing method can be realized by using dry air. The flow rate of the cleaning gas to be injected is generally in the range of 0.1 SLM to 10 SLM, although the optimum value varies depending on the size and size of the panel, the thickness of the glass frit material member and the size of the top unevenness, and the like. (SLM: unit of liters for the amount of gas supplied per minute in the standard state of gas). If the gas flow rate is too small, external air may be mixed in or the cleaning may be insufficient. Conversely, if the gas flow rate is too high, it may be disadvantageous in terms of cost. The top of the annular glass frit sealing member and the substrate are in contact with each other, but the top of the annular glass frit sealing member is not a perfect plane and has an unevenness of several tens to hundreds of micrometers. is doing. That is, a slight gap is formed at the contact interface between the top of the annular glass frit sealing member and the surface of the front plate due to the unevenness. Accordingly, the cleaning gas blown into the “space between the front plate and the back plate” is removed from the gap region between the annular glass frit sealing member and the substrate until the glass frit sealing member is softened. Will be discharged.

  After sealing, the space between the front plate and the back plate is evacuated while maintaining the front plate and the back plate at a temperature slightly lower than the temperature during the sealing process. Specifically, the temperature is lower than when the front plate and the rear plate are sealed (that is, the temperature at which the solidified state of the glass frit sealing member is maintained, and is about 10 to 50 ° C. lower than the melting temperature of the glass frit. While maintaining the temperature, gas is exhausted through the tip tube until the space between the front plate and the back plate is in a vacuum state. After evacuation, cool the front and back plates to near room temperature, then introduce the discharge gas into the "space between the front and back plates", and introduce the discharge gas when the specified pressure is reached. Stop (enclosed). Finally, the PDP is completed by melting the chip tube and sealing and cutting the gas.

[ Inert gas supply in front plate cooling process ]
Next, the “starting temperature of the inert gas supply when the front plate is cooled”, which is one of the features of the present invention, will be described. This “starting temperature of the inert gas supply when the front plate is cooled” is based on the graphs of FIGS. 7 and 8 described below. The graphs of FIG. 7 and FIG. 8 are experimental results obtained by subjecting the front plate after vacuum baking to cooling. Through this experimental result, the inventors of the present application stated that “the impurity gas adsorbed on the protective layer is once desorbed by vacuum baking. However, it has been found that the hydrocarbon gas, among the impurity gases, is adsorbed again on the protective layer depending on the subsequent cooling operation.

(Dependence of hydrocarbon gas adsorption amount on inert gas supply start temperature)
FIG. 7 is a “graph showing the dependence of the hydrocarbon gas adsorption amount on the inert gas supply start temperature” (the experiment for obtaining the graph will be described later in “Examples”). In this graph, the correlation between the inert gas supply start temperature (° C.) and the degassing strength (au) of the hydrocarbon-based gas is shown. “Inert gas supply start temperature (° C.)” is a temperature at which supply of an inert gas is started when the front plate is cooled after vacuum baking. The degassing strength (au) suggests the amount of adsorption of hydrocarbon gas in the protective layer of the front plate. That is, it means that the larger the value of the degassing strength (au), the larger the amount of adsorption of hydrocarbon-based gas that is re-adsorbed on the protective layer of the front plate during cooling.

  Referring to FIG. 7, when the inert gas is supplied after the front plate is cooled to room temperature (25 ° C.) after vacuum baking (“1” shown in the graph of FIG. 7), the degassing strength is 8.14. On the other hand, when an inert gas is supplied in the cooling process after vacuum baking, that is, when an inert gas is supplied at a stage where the temperature of the front plate reaches 400 ° C., 350 ° C., 300 ° C. and 250 ° C. ("2" shown in the graph of FIG. 7) The degassing strength is 0.301 to 0.54. That is, according to FIG. 7, when the supply of the inert gas is started in the middle of lowering the temperature of the front plate to 400 ° C., 350 ° C., 300 ° C. and 250 ° C. during cooling after vacuum baking, , “The amount of hydrocarbon gas resorbed on the protective layer” can be significantly reduced. Therefore, one of the features of the present invention is that when the front plate is subjected to a heat treatment in a vacuum atmosphere and then subjected to a cooling treatment, the inert gas is supplied in a temperature range from the highest temperature during heating to 250 ° C. or higher. It will be understood that by starting and cooling the front plate under an inert gas atmosphere, the amount of adsorption of hydrocarbon gas in the protective layer of the front plate is reduced.

Here, the protective layer from which impurity gases such as H ₂ O, CO ₂ , and hydrocarbon are desorbed by vacuum baking may have an activated adsorption site. In particular, the protective layer from which a large amount of impurity gas has been detached has more activation sites. When such activated sites are exposed to the atmosphere, atmospheric moisture can be adsorbed to such sites. Therefore, by examining the amount of adsorbed moisture, the amount of the activation site of the protective layer can be grasped, and consequently the amount of the desorbed impurity gas can be indirectly grasped.

  FIG. 8 is a “graph showing the dependency of the amount of moisture adsorbed on the activation site on the inert gas supply start temperature” (the experiment for obtaining the graph will be described later in “Examples”). In this graph, the correlation between the inert gas supply start temperature (° C.) and the degassing strength (a.u) of the moisture gas is shown. As described above, the “inert gas supply start temperature (° C.)” is a temperature at which the supply of the inert gas is started when the front plate is cooled after the vacuum baking. The degassing strength (au) of the moisture gas indicates the amount of moisture gas adsorbed at the activation site. The larger the degassing strength (au) value, the more the moisture gas adsorption amount adsorbed on the protective layer of the front plate. This indicates that there is a large amount of impurity gas, that is, the amount of desorbed impurity gas is large.

  Referring to FIG. 8, when an inert gas is supplied in the process of cooling the front plate to 400 ° C., 350 ° C., and 300 ° C. after vacuum baking (“5” shown in the graph of FIG. 8), the degassing strength is 4 When the inert gas is supplied after cooling the front plate to 250 ° C. after vacuum baking (“4” shown in the graph of FIG. 8), the degassing strength is in the range of .0 to 5.0. Becomes 3.0 to 4.0. That is, based on FIG. 8, when the inert gas supply is performed until the front plate temperature is lowered to 300 ° C. during cooling after vacuum baking, the inertness is reduced after the front plate temperature is lowered to 250 ° C. It can be seen that the degassing strength is higher than that in the case of supplying gas, and the amount of moisture gas adsorbed at the activation site is larger. Here, as described above, the “amount of moisture gas adsorbed at the activation site” can be considered to be the same as the “amount of desorbed impurity gas”. Therefore, starting the inert gas supply at a higher temperature can reduce the hydrocarbon-based gas that is re-adsorbed to the protective layer during cooling, and in particular, supply the inert gas until the temperature of the front plate drops to 300 ° C. The amount of hydrocarbon gas that is re-adsorbed on the protective layer during the cooling process after vacuum baking is reduced compared to when the inert gas supply is started after the front plate temperature is lowered to 250 ° C. Can be made. From the above, one of the features of the present invention is that when the front plate is subjected to a heat treatment in a vacuum atmosphere and then subjected to a cooling treatment, the inert gas is supplied in a temperature range from a maximum temperature during heating to 300 ° C. or higher. It will be understood that by starting and cooling the front plate under an inert gas atmosphere, the amount of adsorption of hydrocarbon gas in the protective layer of the front plate is further reduced.

  In addition, when the protective layer having an activation site due to vacuum baking is exposed to the atmosphere, moisture in the atmosphere can be adsorbed to the activation site, but such moisture is adsorbed in a form that is very easily desorbed. Please keep in mind. That is, “adsorbed moisture” can be easily desorbed by heating at a relatively low temperature. Therefore, during the above-described cleaning treatment, that is, when heating in a sealed exhaust furnace while blowing nitrogen gas as a cleaning gas between the front plate and the back plate, adsorbed moisture is easily desorbed from the protective layer. As a result, it is possible to finally obtain a protective layer from which moisture gas components are effectively desorbed (the desorption temperature is about the moisture adsorbed to the protective layer exposed to the atmosphere after vacuum baking). The inventors of the present application have found that there is a peak in the range of 200 ° C. or more and 300 ° C. or less). In other words, according to the production method of the present invention, it is possible to finally obtain a protective layer from which not only hydrocarbon gas but also moisture gas is effectively desorbed.

[ Cooling end temperature ]
In the present invention, when the front plate heat-treated in a vacuum atmosphere is subjected to a cooling treatment, the supply of the inert gas is started in a temperature range from the maximum temperature during heating to 250 ° C. or higher (preferably 300 ° C. or higher). The front plate is cooled in an inert gas atmosphere. Here, it is preferable that the front plate is finally cooled to a temperature of 100 ° C. or lower. Specifically, when taking out the front plate (1) from the baking chamber (41) as shown in FIG. 3, it is preferable to cool to a temperature of 100 ° C. or less in advance. This is because when the protective layer is exposed to an air atmosphere at a temperature higher than normal temperature, hydroxylation or carbonation of the surface region of the protective layer can be promoted by reaction with H ₂ O or CO ₂ in the air. . Therefore, when carrying out step (ii) of the present invention, it is preferable that the front plate is finally cooled to a temperature of 100 ° C. or lower. Incidentally, this “100 ° C. or lower” is based on the boiling point of water (100 ° C.).

[ Protective layer in the present invention]
Next, the “protective layer” which is one of the characteristic portions of the present invention will be described in detail. As shown in FIG. 2B, the protective layer (16) includes a base film (16a) formed on the dielectric layer (15), and magnesium oxide (MgO) crystal particles (MgO) on the base film (16a). 16b) is preferably composed of agglomerated particles (16b ′) obtained by aggregating a plurality of particles. In the protective layer (16), the base film (16a) is formed of a metal oxide selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). More preferably, in the present invention, a metal comprising at least two oxides selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). It is desirable that it be formed of an oxide.

  The base film (16a) is formed of a single material pellet of magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO), or a pellet formed by mixing these materials. It can be formed by a film method. As a thin film forming method, a known method such as an electron beam evaporation method, a sputtering method, or an ion plating method can be applied. For example, about 1 Pa in the sputtering method and about 0.2 Pa in the electron beam vapor deposition method, which is an example of the vapor deposition method, can be considered as the upper limit of the pressure that can actually be taken. In addition, the atmosphere during film formation of the base film (16a) is preferably performed in a sealed state that is blocked from the outside in order to prevent moisture adhesion and adsorption of impurities, and by adjusting the atmosphere during film formation A base film (16a) made of a metal oxide having predetermined electron emission characteristics can be formed.

  Next, the agglomerated particles (16b ') of the magnesium oxide (MgO) crystal particles (16b) deposited on the base film (16a) will be described. These crystal particles (16b) can be produced by either a gas phase synthesis method or a precursor firing method. In the gas phase synthesis method, magnesium metal material having a purity of 99.9% or more is heated in an atmosphere filled with an inert gas, and magnesium is directly oxidized by introducing a small amount of oxygen into the atmosphere. And crystal grains (16b) of magnesium oxide (MgO) can be produced.

On the other hand, in the precursor firing method, a magnesium oxide (MgO) precursor is uniformly fired at a high temperature of about 700 ° C. or higher, and this is gradually cooled to obtain magnesium oxide (MgO) crystal particles (16b). it can. Examples of the precursor include magnesium alkoxide (Mg (OR) ₂ ), magnesium acetylacetone (Mg (acac) 2), magnesium hydroxide (Mg (OH) ₂ ), magnesium carbonate (MgCO ₂ ), magnesium chloride (MgCl ₂ ). ), Magnesium sulfate (MgSO ₄ ), magnesium nitrate (Mg (NO ₃ ) ₂ ), or magnesium oxalate (MgC ₂ O ₄ ). Depending on the selected compound, it may take the form of a hydrate, but such a hydrate can also be used in the present invention. The above compound is adjusted so that the purity of magnesium oxide (MgO) obtained after firing is 99.95% or more, preferably 99.98% or more. If these compounds contain a certain amount or more of various impurity elements such as alkali metals, B, Si, Fe, and Al, unnecessary interparticle adhesion and sintering occur during heat treatment, and highly crystalline magnesium oxide ( This is because it is difficult to obtain MgO) crystal particles. For this reason, it is necessary to adjust the precursor in advance by removing the impurity element.

  Magnesium oxide (MgO) crystal particles (16b) obtained by any one of the above methods are dispersed in a solvent, and the dispersion liquid is sprayed, screen-printed, slit-coated, electrostatically applied, or the like as a base film (16a) is dispersed and dispersed on the surface. Thereafter, by removing the solvent through a drying / firing process, the magnesium oxide (MgO) crystal particles (16b) can be fixed on the surface of the base film (16a).

  As a method for dispersing and fixing the magnesium oxide (MgO) crystal particles (16b) on the surface of the base film (16a), a temperature of about 400 ° C. or less is used from the viewpoint of suppressing the reaction with the impurities of the base film (16a). It is desirable to carry out at a low temperature.

  Further, a “protective layer” which is one of the characteristic portions of the present invention will be described in detail. In the production method of the present invention, a metal oxide comprising at least two oxides selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide, the metal oxide having a specific orientation plane in X-ray diffraction analysis. It is preferable to form a protective layer comprising a metal oxide in which a peak exists between the minimum diffraction angle and the maximum diffraction angle generated from the simple substance of the oxide constituting the object. It is preferable to form the base film (16a) from such a metal oxide. In other words, the base film (16a) of the protective layer is made of at least two oxides selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). In the X-ray diffraction analysis of the surface of the base film (16a) formed by a metal oxide, the minimum diffraction angle and the maximum diffraction angle generated from a single oxide constituting the metal oxide in a specific orientation plane Make sure there are peaks between them.

  FIG. 9 is a diagram showing an X-ray diffraction result on the surface of the base film (16a) constituting the protective layer (16) of the PDP in the embodiment of the present invention. FIG. 9 also shows the results of X-ray diffraction analysis of magnesium oxide (MgO) alone, calcium oxide (CaO) alone, strontium oxide (SrO) alone, and barium oxide (BaO) alone.

  In FIG. 9, the horizontal axis represents the Bragg diffraction angle (2θ), and the vertical axis represents the intensity of the X-ray diffraction wave. The unit of the diffraction angle is shown in degrees when one round is 360 degrees, and the intensity is shown in an arbitrary unit. In the figure, the crystal orientation plane which is a specific orientation plane is shown in parentheses. As shown in FIG. 9, with respect to the crystal orientation plane (111), the diffraction angle is 32.2 degrees for calcium oxide (CaO) alone, the diffraction angle is 36.9 degrees for magnesium oxide (MgO) alone, and the diffraction angle is for strontium oxide alone. It can be seen that 30.0 degrees and barium oxide alone has a peak at a diffraction angle of 27.9 degrees.

  FIG. 9 shows an X-ray diffraction result when the single component constituting the base film (16a) is two components. That is, the X-ray diffraction result of the base film (16a) formed using magnesium oxide (MgO) and calcium oxide (CaO) alone is shown as point A, using magnesium oxide (MgO) and strontium oxide (SrO) alone. The X-ray diffraction result of the formed base film (16a) is B point, and further, the X-ray diffraction result of the base film (16a) formed using a simple substance of magnesium oxide (MgO) and barium oxide (BaO) is C point. Show.

  As can be seen from the X-ray diffraction results shown in the figure, the point A is a diffraction angle 36.9 of magnesium oxide (MgO) alone, which is the maximum diffraction angle of a single oxide at (111) of the crystal orientation plane as a specific orientation plane. There is a peak at a diffraction angle of 36.1 degrees, which is between 1 degree and the diffraction angle of calcium oxide (CaO) alone, which is the minimum diffraction angle, of 32.2 degrees. Similarly, peaks at points B and C exist at 35.7 degrees and 35.4 degrees between the maximum diffraction angle and the minimum diffraction angle, respectively.

  FIG. 10 shows the X-ray diffraction result when the single component constituting the base film (16a) is three or more components, as in FIG. That is, FIG. 10 shows the results obtained when magnesium oxide (MgO), calcium oxide (CaO), and strontium oxide (SrO) are used as the single component, point D, magnesium oxide (MgO), calcium oxide (CaO), and oxidation. The results when barium (BaO) is used are indicated by point E, and the results when calcium oxide (CaO), strontium oxide (SrO) and barium oxide (BaO) are used are indicated by point F.

  As can be seen from the X-ray diffraction results shown in the figure, the point D is the diffraction angle 36.9 of magnesium oxide (MgO) alone, which is the maximum diffraction angle of a single oxide at the crystal orientation plane (111) as the specific orientation plane. There is a peak at a diffraction angle of 33.4 degrees, which is between 1 degree and the diffraction angle of 30.0 degrees of strontium oxide (SrO) alone, which is the minimum diffraction angle. Similarly, peaks at points E and F exist at 32.8 degrees and 30.2 degrees between the maximum diffraction angle and the minimum diffraction angle, respectively.

  As described above, the base film (16a) of the PDP protective layer according to the present invention is specified in the X-ray diffraction analysis of the metal oxide constituting the base film (16a), whether it is a two-component or three-component component. A peak is present between the minimum diffraction angle and the maximum diffraction angle of a peak generated from a single oxide constituting the metal oxide on the orientation plane.

  In the above description, (111) has been described as the crystal orientation plane as the specific orientation plane, but the peak position of the metal oxide is the same as that described above when other crystal orientation planes are also targeted.

  The depth from the vacuum level of calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) exists in a shallow region as compared with magnesium oxide (MgO). Therefore, when driving a PDP, when electrons existing at the energy levels of calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) transition to the ground state of the xenon (Xe) ion, Auger It is considered that the number of electrons emitted due to the effect increases as compared with the case of transition from the energy level of magnesium oxide (MgO).

  As a result of X-ray diffraction analysis, the metal oxides having the characteristics shown in FIGS. 9 and 10 have their energy levels between the single oxides constituting them. Therefore, the energy level of the base film (16a) is also present between the single oxides, and the amount of energy acquired by other electrons by the Auger effect is sufficient to be released beyond the vacuum level. Can do.

  As a result, the base film (16a) can exhibit better secondary electron emission characteristics compared to magnesium oxide (MgO) alone, and therefore, the discharge sustaining voltage can be reduced. That is, particularly when the xenon (Xe) partial pressure as the discharge gas is increased in order to increase the luminance, it becomes possible to reduce the discharge voltage and realize a low-voltage and high-luminance PDP.

  Here, in the PDP obtained by the manufacturing method of the present invention, the discharge sustaining voltage of the PDP when the configuration of the base film (16a) is changed will be described. First, as a sample according to the present invention, Sample A (underlying film is a metal oxide of magnesium oxide and calcium oxide), Sample B (underlying film is a metal oxide of magnesium oxide and strontium oxide), Sample C (underlying film is magnesium oxide) And sample D (metal oxide of magnesium oxide, calcium oxide and strontium oxide) and sample E (metal oxide of magnesium oxide, calcium oxide and barium oxide) are prepared. As a comparative example, a base film made of magnesium oxide alone was prepared.

  When the discharge sustaining voltage is measured for these samples A to E, when the comparative example is 100, sample A is 90, sample B is 87, sample C is 85, sample D is 81, and sample E is 82. The value is shown.

  When the partial pressure of the discharge gas xenon (Xe) is increased from 10% to 15%, the luminance increases by about 30%, but in the comparative example in which the base film (16a) is made of magnesium oxide (MgO) alone. The sustaining voltage increases by about 10%. On the other hand, in the PDP obtained by the manufacturing method of the present invention, the discharge sustaining voltage can be reduced by about 10% to 20% in all of the sample A, sample B, sample C, sample D, and sample E compared to the comparative example. Therefore, it can be said that the discharge start voltage is within the normal operating range, and it can be said that a high-luminance and low-voltage driven PDP can be realized.

  Calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) are highly reactive as a single substance, and thus easily react with impurities. By using the structure of the product, the reactivity is reduced, and a crystal structure with few impurities and oxygen vacancies is formed. That is, by using calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) as a metal oxide structure, excessive emission of electrons during driving of the PDP is suppressed, and low voltage driving and two-way driving are possible. In addition to the effect of achieving secondary electron emission performance, the effect of moderate electron retention characteristics 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.

  Next, the agglomerated particles (16b ') formed by aggregating a plurality of magnesium oxide (MgO) crystal particles (16b) provided on the base film (16a) will be described in detail. Magnesium oxide (MgO) agglomerated particles (16b ') have been confirmed by experiments of the present inventor mainly to suppress the "discharge delay" in the write discharge and to improve the temperature dependence of the "discharge delay". Has been. Therefore, in the present invention, the aggregated particles (16b ′) are disposed as an initial electron supply unit required at the time of rising of the discharge pulse by utilizing a property that is superior in advanced initial electron emission characteristics compared to the base film (16a). .

  The “discharge delay” is considered to be mainly caused by a shortage of the amount of initial electrons that serve as a trigger emitted from the surface of the base film (16a) into the discharge space at the start of discharge. Therefore, in order to contribute to the stable supply of initial electrons to the discharge space, the aggregated particles (16b ') of magnesium oxide (MgO) are dispersedly arranged on the surface of the base film (16a). As a result, abundant electrons are present in the discharge space when the discharge pulse rises, 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 has a high definition. In the configuration in which the metal oxide aggregated particles (16b ′) are disposed on the surface of the base film (16a), in addition to the effect of mainly suppressing the “discharge delay” in the write discharge, the temperature dependence of the “discharge delay”. The effect which improves can also be acquired.

  As described above, in the PDP obtained by the production method of the present invention, the base film (16a) that achieves both the low voltage driving and the charge retention effect, and the magnesium oxide (MgO) agglomerated particles (MgO) that have the effect of preventing discharge delay ( 16b ′), a high-definition PDP can realize high-speed driving at a low voltage and a high-quality image display performance with suppressed lighting failure.

  Incidentally, in a preferred embodiment of the present invention, the aggregated particles (16b ′) in which several crystal particles (16b) are aggregated are discretely dispersed on the base film (16a) and distributed almost uniformly over the entire surface. A plurality are attached so as to. FIG. 11 is an enlarged view for explaining the aggregated particles (16b ').

  As shown in FIG. 11, the aggregated particles (16b ') are those in which crystal particles (16b) having a predetermined primary particle size are aggregated or necked. In other words, it is not bonded as a solid with a large bonding force, but a plurality of primary particles form an aggregate body due to static electricity, van der Waals force, etc., and due to external stimuli such as ultrasound , Part or all of them are bonded to such a degree that they become primary particles. The particle diameter of the aggregated particles is about 1 μm, and the crystal particles preferably have a polyhedral shape having seven or more faces such as a tetrahedron and a dodecahedron.

  Moreover, the particle size of the primary particles of the crystal particles (16b) can be controlled by the generation conditions of the crystal particles (16b). For example, when an MgO precursor such as magnesium carbonate or magnesium hydroxide is calcined and produced, the particle size can be controlled by controlling the calcining temperature and the calcining atmosphere. Generally, the firing temperature can be selected in the range of 700 ° C. to 1500 ° C., but the particle size can be controlled to about 0.3 to 2 μm by making the firing temperature relatively higher than about 1000 ° C. It is. Further, by obtaining crystalline particles (16b) by heating the MgO precursor, a plurality of primary particles are bonded together by a phenomenon called agglomeration or necking in the production process to obtain agglomerated particles (16b ′). Can do.

  FIG. 12 shows the discharge delay and the inside of the protective layer when the base film (16a) made of a metal oxide of magnesium oxide (MgO) and calcium oxide (CaO) is used in the PDP in the embodiment of the present invention. It is a figure which shows the relationship with calcium (Ca) density | concentration. The base film (16a) is composed of a metal oxide composed of magnesium oxide (MgO) and calcium oxide (CaO), and the metal oxide is magnesium oxide (MgO) in X-ray diffraction analysis on the surface of the base film (16a). A peak is present between the diffraction angle at which the peak is generated and the diffraction angle at which the calcium oxide (CaO) peak is generated. FIG. 12 shows the case where only the base film (16a) is used as the protective layer and the case where the aggregated particles (16b ′) are arranged on the base film (16a). The discharge delay is shown in FIG. The case where calcium (Ca) is not contained is shown as a reference.

  The electron emission performance is a numerical value indicating that the larger the electron emission amount, the larger the electron emission performance, and it is expressed by the initial electron emission amount determined by the surface state, the gas type and the state. Although the initial electron emission amount can be measured by a method of measuring the amount of electron current emitted from the surface by irradiating the surface with ions or an electron beam, it is difficult to evaluate the front surface of the PDP in a non-destructive manner. Accompanied by. Therefore, the method described in JP 2007-48733 A was used. That is, among the delay times at the time of discharge, a numerical value called a statistical delay time, which is a measure of the likelihood of occurrence of discharge, is measured, and when the reciprocal is integrated, a numerical value corresponding to the initial electron emission amount is obtained. That is, evaluation is performed using such numerical values. The delay time at the time of discharge means the time of the delay of discharge that is delayed after the rise of the pulse, and the discharge delay is the time when the initial electrons that trigger when the discharge starts from the surface of the protective layer to the discharge space. It is considered that the main factor is that it is difficult to be released.

  As is clear from FIG. 12, in the case of only the base film (16a) and the case where the aggregated particles (16b ′) are arranged on the base film (16a), the case of only the base film (16a) is calcium (Ca ) While the discharge delay increases with increasing concentration, the discharge delay can be significantly reduced by arranging the aggregated particles (16b ′) on the base film (16a), and the calcium (Ca) concentration increases. It can be seen that the discharge delay hardly increases.

  Next, the results of experiments conducted to confirm the effect of the protective layer having aggregated particles (16b ′) in the embodiment of the present invention will be described. First, a PDP having a base film (16a) having a different structure and agglomerated particles (16b ') provided on the base film (16a) was experimentally manufactured. Prototype 1 is a PDP in which a protective layer made only of a magnesium oxide (MgO) base film (16a) is formed. Prototype 2 is only a base film (16a) in which magnesium oxide (MgO) is doped with impurities such as Al and Si. PDP with a protective layer, Prototype 3, formed a protective layer in which only primary particles of magnesium oxide (MgO) crystal particles (16b) were sprayed and adhered on a base film (16a) made of magnesium oxide (MgO). PDP.

  On the other hand, prototype 4 is a PDP obtained by the production method of the present invention, and uses sample A described above as a protective layer. That is, the protective layer includes a base film (16a) made of a metal oxide of magnesium oxide (MgO) and calcium oxide (CaO), and aggregated particles obtained by aggregating crystal particles (16b) on the base film (16a). (16b ′) is attached so as to be distributed almost uniformly over the entire surface. In addition, the base film (16a) is between the minimum diffraction angle and the maximum diffraction angle of the peak generated from a single oxide constituting the base film (16a) in the X-ray diffraction analysis of the surface of the base film (16a). A peak is present. That is, the minimum diffraction angle in this case is 32.2 degrees for calcium oxide (CaO), the maximum diffraction angle is 36.9 degrees for magnesium oxide (MgO), and the peak of the diffraction angle of the base film 91 is 36.1 degrees. To exist.

  These PDPs were examined for their electron emission performance and charge retention performance, and the results are shown in FIG. The electron emission performance is evaluated by the above-described method, and the charge retention performance is measured by using a voltage (hereinafter referred to as Vscn lighting voltage) applied to the scan electrode necessary for suppressing the charge emission phenomenon when the PDP is manufactured. ) Voltage value was used. That is, a lower Vscn lighting voltage indicates a higher charge retention capability. This makes it possible to use components having a low withstand voltage and a small capacity as the power source and each electrical component in designing the PDP. In a current product, an element having a withstand voltage of about 150 V is used as a semiconductor switching element such as a MOSFET for sequentially applying a scanning voltage to a panel, and the Vscn lighting voltage is about 120 V in consideration of variation due to temperature. It is desirable to keep it below.

  As is apparent from FIG. 13, aggregated particles (16b ′) obtained by aggregating single crystal particles (16b) of magnesium oxide (MgO) are sprayed on the entire surface of the base film (16a) in the embodiment of the present invention. Uniformly distributed prototype 4 can be used as prototype 1 in the case where the Vscn lighting voltage can be set to 120 V or less and the electron emission performance is a protective layer made of only magnesium oxide (MgO). Compared to this, much better characteristics can be obtained.

  In general, the electron emission capability and the charge retention capability of the protective layer of the PDP are contradictory. For example, it is possible to improve the electron emission performance by changing the film forming conditions of the protective layer, or by forming a film by doping impurities such as Al, Si, and Ba in the protective layer. The Vscn lighting voltage also increases.

  In the PDP of the prototype 4 in the embodiment of the present invention, the electron emission capability is more than eight times that of the prototype 1 using a protective layer made only of magnesium oxide (MgO), As a holding capability, a Vscn lighting voltage of 120 V or less can be obtained. Therefore, it is useful for PDPs with a large number of scanning lines and a small cell size due to high definition, satisfying both electron emission capability and charge retention capability, and reducing discharge delay and good image display Can be realized.

  Next, the particle size of the crystal particles (16b) will be described in detail. In the following description, the particle diameter means an average particle diameter, and the average particle diameter means a volume cumulative average diameter (D50).

  FIG. 14 shows an experimental result of examining the electron emission performance in the prototype 4 of the present invention described with reference to FIG. 13 by changing the grain size of the crystal particles (16b). In FIG. 14, the particle diameter of the crystal particle (16b) was measured by SEM observation of the crystal particle. As shown in FIG. 14, it can be seen that when the particle size is reduced to about 0.3 μm, the electron emission performance is lowered, and when it is approximately 0.9 μm or more, high electron emission performance is obtained.

  By the way, in order to increase the number of electrons emitted in the discharge cell, it is desirable that the number of crystal particles (16b) per unit area on the base film is large. Corresponding cells may be formed by the crystal particles existing in the portion corresponding to the top of the partition wall of the back plate that is in close contact with the protective layer of the face plate, so that the top of the partition wall is damaged and the material gets on the phosphor. It has been found that a phenomenon occurs in which the LED does not turn on and off normally. This phenomenon of partition wall breakage is unlikely to occur unless the crystal particles (16b) are present at the portion corresponding to the top of the partition wall. Therefore, if the number of attached crystal particles (16b) increases, the probability of partition wall breakage increases. Become. From this point of view, when the crystal particle diameter is increased to about 2.5 μm, the probability of partition wall breakage increases rapidly, and when the crystal particle diameter is smaller than 2.5 μm, the probability of partition wall breakage is kept relatively small. be able to.

  From the above results, in the production method of the present invention, if the crystal particles (16b) used for the protective layer are those having a particle size in the range of 0.9 μm to 2 μm, the above-described effects of the present invention can be stabilized. It was found that it can be obtained. In addition, although demonstrated using the magnesium oxide (MgO) particle | grains as a crystal particle (16b), other single crystal particle | grains have Sr, Ca, Ba, Al, etc. which have high electron emission performance similarly to magnesium oxide (MgO). Since the same effect can be obtained even if crystal particles of the metal oxide are used, the particle type is not limited to magnesium oxide (MgO).

  In general, the “protective layer in the present invention” has a secondary electron emission characteristic in the protective layer improved in the PDP in which the protective layer is formed based on the above-described knowledge. Even when the Xe gas partial pressure of the gas is increased, the discharge start voltage can be reduced. That is, the PDP obtained by the present invention can be excellent in display performance capable of being driven with high brightness and low voltage even in a high-definition image.

  As mentioned above, although embodiment of this invention has been described, it has only illustrated the typical example to the last. Therefore, those skilled in the art will readily understand that the present invention is not limited thereto and various modifications can be made. For example, the following modifications can be mentioned.

In the above description, the mode in which the front plate is cooled in the baking chamber has been illustrated, but the front plate may be cooled in the load lock chamber. A specific process mode in this case will be described with reference to FIGS. The front plate on which the protective layer is formed is first placed on a tray (not shown) placed in the load lock chamber (49). Next, the tray and the front plate (1) are transferred to the baking chamber (41) through the gate (48) using a transfer system (not shown). After the transfer, the gate (48) is closed, and the inside of the baking chamber (41) is evacuated using the pump (42). When the internal atmosphere of the baking chamber reaches a predetermined vacuum pressure (for example, 0.001 Pa or less) by evacuation, electric power is supplied to the lamp (43) in the baking chamber (41) to start heating the front plate. Although the temperature of the front plate rises due to heating, it is heated until it reaches a certain predetermined temperature (for example, about 500 ° C.), and the maximum temperature reached for several minutes (for example, about 2 minutes). After this holding, the cooling of the front plate (1) is started by turning off the power supplied to the lamp (43). While the temperature of the front plate (1) is at a predetermined temperature (250 ° C. or more and 500 ° C. or less), the valve (47) is closed, and nitrogen gas is introduced into the baking chamber (41) using the flow rate controller (45). The pressure in the baking chamber (41) is set to atmospheric pressure. Then, the tray and the front plate are transferred to a load lock chamber (49) filled with nitrogen gas as an inert gas, and the front plate temperature in the load lock chamber (49) is reduced to 100 ° C. Cool the face plate.

Alternatively, the following process mode is possible (described with reference to FIGS. 3 and 5). First, the front plate on which the protective layer is formed is placed on a tray placed in the load lock chamber (49). Next, the load lock chamber (49) is evacuated using a pump. When the inside of the load lock chamber (49) reaches a predetermined pressure (for example, 10 Pa or less) by evacuation, the gate (48) is opened, and the baking chamber (41) and the load lock chamber (49), which have been evacuated in advance, are opened. Communicate. Then, using the transport system, the tray and the front plate (1) are transported to the baking chamber (41) through the gate (48). After the gate (48) is closed, when the pressure in the baking chamber (41) reaches a predetermined pressure (for example, 0.001 Pa or less), power is supplied to the lamp (43), and the front plate (1) is brought to about 500 ° C. Heat. After holding at the maximum heating temperature of 500 ° C. for several minutes (for example, 2 minutes), the power supplied to the lamp (43) is turned off, and the front plate is cooled. When the temperature of the front plate reaches a predetermined temperature (for example, 450 ° C. or lower), the gate (48) is opened, and the load lock chamber (49) and the baking chamber (41) that are evacuated are communicated. Then, using a transfer system (not shown), the tray and the front plate are transferred to the load lock chamber (49) through the gate (48). Next, the gate (48) is closed, an inert gas is supplied into the load lock chamber (49) using a gas supply system (not shown), and the inside of the load lock chamber (49) is brought to atmospheric pressure. And after cooling until the temperature of a front plate will be 100 degrees C or less, a front plate is taken out. When such a process mode is adopted, the stay time of the front plate in the baking chamber, which is the most expensive in terms of the equipment configuration, is shortened, so that the price of the vacuum baking apparatus can be further suppressed.

In the above description, an example in which an inert gas is supplied when the front plate is cooled is illustrated, but the pressure of the supplied inert gas is preferably 10 Pa or more and atmospheric pressure or less. If the pressure is too low, the effect of increasing the boiling point of hydrocarbon deposits adhering to the inner wall of the baking chamber, etc., and the effect of diluting hydrocarbon gases with inert gas will be reduced. Yes (see “Examples” below).

In the above description, an example in which power is supplied to the lamp after the inside of the baking chamber reaches 0.001 Pa or less is illustrated. The lower this ultimate pressure, the easier the cleaning of the protective layer. However, if an excessively low pressure is to be realized, a pump having an unrealistic super-large exhaust capacity is required. Therefore, it can be said that this ultimate pressure is preferably 0.00001 Pa or more and 0.1 Pa or less.

In the above description, magnesium oxide (MgO) crystal particles are dispersed in a solvent, and the dispersion liquid is dispersed and dispersed on the surface of the base film. Thereafter, the solvent is removed through a drying and firing process, and magnesium oxide (MgO) In the above embodiment, the protective layer is vacuum-baked after fixing the crystal particles on the surface of the base film (16a). However, by performing the vacuum baking without the firing step, the crystal grains of magnesium oxide (MgO) It is also possible to fix the base film to the surface and clean the protective layer (particularly the base film) at once. Such a process mode has the advantage that not only large-scale firing facilities are unnecessary, but also the energy required for production can be reduced and the production cost of the PDP can be reduced.

In the above description, the protective layer has been mainly premised on an embodiment comprising at least one metal oxide selected from the group consisting of magnesium oxide, calcium oxide, strontium oxide, and barium oxide. It is not necessarily limited to such an embodiment. For example, the protective layer may be as disclosed in JP-A-2004-47193 (for example, the protective layer is formed of a lanthanoid oxide such as lanthanum oxide or cerium oxide) Even in such a case, the effect of the present invention is not changed.

● In terms of the effect of the present invention, a method for producing a PDP formed by applying and drying a paste containing fine metal oxide particles in addition to a protective layer formed by an electron beam evaporation method The present invention can also be suitably applied to. The inside of the baking chamber (41) is evacuated by the pump (42) and can be kept in a vacuum.

● The dielectric layer formed on the front plate may have a two-layer structure including a first dielectric layer and a second dielectric layer. In this case, the dielectric material of the first dielectric layer is selected from 20% to 40% by weight of bismuth oxide (Bi ₂ O ₃ ), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). At least one selected from molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), cerium oxide (CeO ₂ ), and manganese dioxide (MnO ₂ ). Those comprising 0.1 wt% to 7 wt% are preferred. In place of molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), cerium oxide (CeO ₂ ), manganese dioxide (MnO ₂ ), copper oxide (CuO), chromium oxide (Cr ₂ O ₃ ), cobalt oxide At least one selected from (Co ₂ O ₃ ), vanadium oxide (V ₂ O ₇ ), and antimony oxide (Sb ₂ O ₃ ) may be contained in an amount of 0.1 wt% to 7 wt%. Further, as components other than the above, zinc oxide (ZnO) is 0 wt% to 40 wt%, boron oxide (B ₂ O ₃ ) is 0 wt% to 35 wt%, and silicon oxide (SiO ₂ ) is 0 wt% to A material composition that does not contain a lead component, such as 15 wt% and aluminum oxide (Al ₂ O ₃ ) 0 wt% to 10 wt% may be included. The first dielectric layer paste having such a composition is printed on the front glass substrate by a die coating method or a screen printing method so as to cover the display electrodes and dried, and then a temperature slightly higher than the softening point of the dielectric material. The first dielectric layer can be formed by firing at 575 ° C. to 590 ° C.
On the other hand, the second dielectric layer contains at least 1 selected from bismuth oxide (Bi ₂ O ₃ ) at 11 wt% to 20 wt%, and further selected from calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). 1.6 wt% to 21 wt% of seeds, 0.1 wt% to 7 wt% of at least one selected from molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), and cerium oxide (CeO ₂ ) Is preferred. Note that instead of molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), and cerium oxide (CeO ₂ ), copper oxide (CuO), chromium oxide (Cr ₂ O ₃ ), cobalt oxide (Co ₂ O ₃ ), At least one selected from vanadium oxide (V ₂ O ₇ ), antimony oxide (Sb ₂ O ₃ ), and manganese oxide (MnO ₂ ) may be contained in an amount of 0.1 wt% to 7 wt%. Further, as components other than the above, zinc oxide (ZnO) is 0 wt% to 40 wt%, boron oxide (B ₂ O ₃ ) is 0 wt% to 35 wt%, and silicon oxide (SiO ₂ ) is 0 wt% to A material composition that does not contain a lead component, such as 15 wt% and aluminum oxide (Al ₂ O ₃ ) 0 wt% to 10 wt% may be included. The second dielectric layer paste having such a composition is printed on the first dielectric layer by a screen printing method or a die coating method and then dried, and then, a temperature slightly higher than the softening point of the dielectric material is 550 ° C. By baking at ˜590 ° C., the second dielectric layer can be formed. The PDP manufactured in this way has little coloring phenomenon (yellowing) of the front glass substrate even when a silver (Ag) material is used for the display electrode, and there is no generation of bubbles in the dielectric layer. In addition, it is possible to realize a dielectric layer having excellent withstand voltage performance.

  Finally, “temperature” in the present invention will be added. The temperature related to the present invention (for example, 250 ° C., 300 ° C. or 100 ° C.) basically indicates the temperature of the front plate (particularly the temperature of the protective layer of the front plate). However, when such temperature cannot be directly grasped, the temperature in the chamber (for example, “atmosphere temperature of the baking chamber”) may be adopted for convenience. At this time, it is preferable to measure the correlation between the temperature of the front plate and the temperature in the chamber in advance. In the present invention, it should be noted that such “front plate temperature” and “in-chamber temperature” are measured using a thermometer or a radiation measuring instrument such as a radiation thermometer.

  A test (vacuum baking test) was performed on the features of the present invention. In particular, the inventors of the present invention, through the test described below, adsorb a large amount of hydrocarbon gas to the protective layer in the process of cooling the front plate including the protective layer after activation by vacuum baking, and after the sealing treatment It has been found that the panel quality is deteriorated due to the decrease in the fluorescence brightness (more specifically, in the completed panel, the adsorbed hydrocarbon gas is desorbed and soot-like deposits are fluorescent. It is thought that it adheres to the body layer and thereby causes luminance degradation).

  The vacuum baking test was performed using a vacuum baking apparatus (40) as shown in FIG. In such a vacuum baking apparatus (40), the inside of the baking chamber (41) is evacuated by the pump (42) and can be kept in a vacuum. As a heating means for the front plate, a lamp (43) and a reflection plate (44) are provided in the baking chamber (41). Nitrogen gas is supplied from the flow controller (45) as an inert gas into the baking chamber (41) through the valve (46). A valve (47) is provided between the baking chamber (41) and the pump (42) so that ON / OFF of exhaust can be switched.

In the vacuum baking test, attention was paid to the atmosphere in the baking chamber when the front plate was cooled after the vacuum baking, and cooling in an inert gas was studied. There are the following two points.
(1) In inert gas, the boiling point of hydrocarbon deposits adhering to the inner wall surface of a baking chamber, which is considered to be a source of hydrocarbon gas, is extremely small compared to vacuum. Therefore, it is expected that the absolute amount of hydrocarbon gas in the cooling atmosphere will be reduced.
(2) When cooling in an inert gas, the concentration of the hydrocarbon-based gas is lower than when cooling in a vacuum. This is because the hydrocarbon-based gas is diluted with an inert gas.

When cooling the front plate heated to 500 ° C. by vacuum baking (the heating time at the maximum heating temperature of 500 ° C. is about 2 minutes), an experiment was conducted to supply nitrogen gas into the baking chamber, and supply of such inert gas. The amount of adsorption of the hydrocarbon-based gas on the front plate relative to the start temperature was measured by a temperature desorption method (TDS: Thermal Desorption Spectroscopy). The results are shown in FIG. The amount of adsorption of the hydrocarbon-based gas was evaluated by the degassing strength of CH ₃ (= mass number 15). Nitrogen gas as an inert gas was supplied until the pressure in the baking chamber reached atmospheric pressure, and then the supply was stopped.

  Referring to FIG. 7, when the vacuum is cooled to room temperature (25 ° C.) (1), a large amount of hydrocarbon gas is adsorbed on the protective layer 9 (degassing strength = 8.14). When the vacuum cooling temperature was 250 ° C. or higher (2), it was found that the amount of adsorption was drastically reduced (degassing strength = 0.301 to 0.543). Therefore, after the front plate is heated to the maximum heating temperature (500 ° C) in vacuum and then cooled, the front plate is exposed to an inert gas from a temperature range of 250 ° C or higher and lower than the maximum heating temperature. However, it has been found that cooling is preferable.

  By the way, when the protective layer cleaned by vacuum baking is exposed to the atmosphere, the activated adsorption site is exposed, so that moisture in the atmosphere is adsorbed on the site. However, it is known that it adsorbs in a form that is very easy to desorb. In other words, when sealing while blowing nitrogen gas, most of it is desorbed and quickly discharged from the space between the two substrates to the outside. In the evaluation by the temperature programmed desorption method, the desorption temperature of moisture desorbed from the protective layer exposed to the atmosphere after vacuum baking has a peak in the range of 200 ° C. or higher and 300 ° C. or lower. However, when cooled to a low temperature in a vacuum, the hydrocarbon-based gas has been adsorbed on the adsorption sites activated in the vacuum, so that the amount of moisture adsorbed after exposure to the air is reduced to 200 ° C. to 300 ° C. No peak appeared in the range below ℃.

FIG. 8 shows the results of evaluating the moisture adsorption amount based on the degassing strength of H ₂ O (= mass number 18) in the experiment obtained in FIG. However, when cooling in vacuum to room temperature (25 ° C) (3), no peak appeared, so the desorption gas intensity at 250 ° C was plotted, and the other inert gas supply start temperature was 250 ° C. In the case of (4) and the case of (5) above 300 ° C., the peak value of the desorption intensity of water that appears in the range of 200 ° C. to 300 ° C. is plotted. From FIG. 8, it was found that when the inert gas supply start temperature is 250 ° C. (4), the amount of moisture adsorbed is smaller than when the inert gas supply start temperature is 300 ° C. or higher (5). That is, when the inert gas supply start temperature was 250 ° C. (4), it was found that the degree of cleanliness of the protective layer was slightly worse than when the inert gas supply start temperature was 300 ° C. or higher (5). Therefore, when the front plate is cooled to the maximum heating temperature (about 500 ° C.) in a vacuum and then cooled, the front plate is changed to an inert gas from a temperature range of 300 ° C. or higher and lower than the maximum heating temperature. It has been found that cooling with exposure is more preferred.

  In addition, each temperature acquired in the said Example was measured by adhere | attaching a thermocouple on a front plate with a ceramic bond.

  Since the PDP finally obtained through the manufacturing method of the present invention has high luminance and low power consumption, it can be suitably used as a plasma television for general homes and a commercial plasma television, and also as various other display devices. It can be used suitably.

DESCRIPTION OF SYMBOLS 1 Front board 2 Back board 10 Board | substrate A by the front board side
11 Front panel side electrode A (display electrode)
12 Scan electrode 12a Transparent electrode 12b Bus electrode 13 Sustain electrode 13a Transparent electrode 13b Bus electrode 14 Black stripe (light shielding layer)
15 Dielectric layer A on the front plate side
DESCRIPTION OF SYMBOLS 16 Protective layer 16a Base film of protective layer 16b Crystal particle | grains 16b 'arrange | positioned on the base film of a protective layer
21 Back plate side electrode B (address electrode)
22 Dielectric layer B on the back plate side
23 partition wall 25 phosphor layer 29 through hole (gas supply opening / cleaning gas blowing opening)
30 Discharge Space 32 Discharge Cell 40 Vacuum Baking Device 41 Baking Chamber 42 Exhaust Pump 43 Lamp 44 Reflector 45 Flow Controller 46 Valve 47 Valve 48 Gate 49 Load Lock Chamber 55 Chip Tube (Exhaust Tube)
56 Frit ring 57 Chuck head 68 Piping 70 Clip 86 Glass frit sealing member

Claims (4)

It has a front plate on which an electrode A, a dielectric layer A and a protective layer are formed on a substrate A, and a back plate on which an electrode B, a dielectric layer B, a partition and a phosphor layer are formed on a substrate B. A plasma display panel manufacturing method comprising:
Prior to subjecting the front plate and the back plate to the sealing treatment, (i) a step of heating the front plate under vacuum, and (ii) a step of cooling the front plate after the heating. ,
In the step (ii), an inert gas supply is started in a temperature range of not more than the maximum temperature during heating in the step (i) to 250 ° C. or more, and the front plate is cooled in an inert gas atmosphere. A method for manufacturing a plasma display panel.   2. The method of manufacturing a plasma display panel according to claim 1, wherein the inert gas supply is started in a temperature range of not more than a maximum temperature during heating in the step (i) to not less than 300 ° C. 3.   3. The method of manufacturing a plasma display panel according to claim 1, wherein in the step (ii), the front plate is cooled to a temperature of 100 ° C. or lower.   A metal oxide comprising at least two oxides selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide, the oxide constituting the metal oxide in a specific orientation plane in X-ray diffraction analysis The said protective layer of the said front plate is formed from the metal oxide in which a peak exists between the minimum diffraction angle and the maximum diffraction angle which generate | occur | produce from the single substance of any one of Claims 1-3 characterized by the above-mentioned. Of manufacturing a plasma display panel.

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