JP2005116359A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device using high voltage, capable of increasing reliability by preventing discharge generation. <P>SOLUTION: The image display device comprises a rear plate having at least an electron beam source, a face plate having a phosphor body for emitting light when receiving an electron beam radiation, and an anode electrode for applying electron acceleration voltage, and an enclosure for making the rear plate and the face plate vacuum-tight to maintain vacuum inside the device. No foreign particle of 10 μm or more exists in the vacuum sealed area of the image display device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image display apparatus using an electron beam such as a field emission display (FED).

  Image display devices such as CRTs are actively researched as they are required to have a larger size. In addition, with the increase in size, it is important to make the device thinner, lighter, and lower in cost. However, CRT deflects electrons accelerated by a high voltage with a deflecting electrode and excites the phosphor on the faceplate. Therefore, when a large format is used, a depth is required in principle, and a thin and lightweight product is provided. Is difficult. The inventors have studied a surface conduction electron-emitting device and an image display device using the surface conduction electron-emitting device as an image display device that can solve the above-described problems.

  The inventors have tried to apply the multi-electron beam source shown in FIG. 10, for example. In the figure, reference numeral 4101 schematically shows a surface conduction electron-emitting device, 4102 is a column direction wiring, 4103 is a row direction wiring, and constitutes a multi-electron beam source wired in a simple matrix. FIG. 10 shows the structure of a cathode ray tube (also referred to as an image display panel) using this multi-electron beam source, and the outer container bottom 4001 provided with the multi-electron beam source (represented as a rear plate). And a side plate 4003 (which may be described as a support frame or an outer container frame), and a face plate 4002 provided with a phosphor layer 4201 and a metal back 4203. In addition, the phosphor layer 4201 on the face plate 4002 is provided with a phosphor that is excited by an electron beam to emit light and a black matrix that suppresses reflection of external light and prevents color mixture of the phosphor. In addition, a high voltage is applied to the phosphor layer 4201 and the metal back 4203 from the high voltage introduction terminal to form an anode electrode. Such an image display device is disclosed in, for example, Patent Document 1.

The image display apparatus as described above applies a high voltage (also referred to as an acceleration voltage or an anode voltage) to the metal back 4203 which is a part of the anode electrode, and between the rear plate 4001 and the face plate 4002. An image is formed by generating an electric field, accelerating the electrons emitted from the electron beam source 4101, exciting the phosphor, and emitting light. Here, since the luminance of the image display device greatly depends on the acceleration voltage, it is necessary to increase the acceleration voltage in order to increase the luminance. In order to reduce the thickness of the image display device, it is necessary to reduce the thickness of the image display panel. Therefore, the distance between the rear plate 4001 and the face plate 4002 must be reduced. As a result, a considerably high electric field is generated between the rear plate 4001 and the face plate 4002.
JP 2002-216633 A

  However, the display panel described above has the following problems.

  FIG. 11 is a schematic view showing a cross section of the display panel described above.

  The image display device includes a rear plate 4001 having an electron beam source 4101 and a face plate 4002 having a metal back 4203 as an anode electrode, and an acceleration voltage Va is applied to the anode electrode 4203. Here, the anode electrode 4203 is insulated by a vacuum gap between the face plate 4002 and the rear plate 4001. Here, the dimension of the vacuum gap defines the depth of the image display panel, and is preferably smaller. However, when the depth of the display panel is reduced, even if the same voltage is applied to the anode electrode 4203, the electric field intensity, which is a value obtained by dividing the same voltage by the distance, increases, and the probability of discharge increases. When the discharge occurs, the image quality of the image display apparatus may be significantly deteriorated, which is a serious problem in improving the reliability of the image display apparatus.

  Here, since electrons emitted from the electron beam source 4101 on the rear plate 4001 must fly to the face plate 4002, the inside of the image display device surrounded by the rear plate 4001, the face plate 4002, and the side wall 4003 is evacuated. Need to be kept. The causes of discharge in vacuum are as follows: (1) Electron emission due to electric field concentration occurs in the microprotrusions existing on the cathode (here, the rear plate 4001), and the microprotrusions are heated by Joule heat due to the current flowing through the microprotrusions. (Cathode heating theory), or the opposite anode (face plate 4002 in this case) is heated by electron impact (anode heating theory), resulting in discharge, (2) clamps, fine particles attached to the electrode, etc. Are released and accelerated by electrostatic force, collide with the electrode, and the electrode and particles are heated to cause discharge (clamp theory).

  Further, when the image display panel is enlarged, there is a high possibility that foreign particles mixed during the manufacturing process and member dropouts falling off the members are mixed in as the area increases. Therefore, the larger the display panel is, the greater the influence of the discharge due to the clamp theory / foreign particles in (2).

  In the manufacturing process of such an image display panel, mixing of foreign particles smaller than 100 μm is equivalent to (1) a structure having a size of several tens to several hundreds μm is built in both the rear plate and the face plate. Particles of the following sizes are difficult to find, (2) The rear plate / face plate has a large substrate size, so it is easy to reattach even when trying to remove foreign matter. (3) Foreign matter removal when the foreign particle size is small Problems such as difficulty in itself occur. Therefore, when designing the manufacturing process of the display panel, it is indispensable to design the foreign matters as described above, such as the prevention / inspection / discovery method / removal method of contamination / generation. For the reasons described above, it has been desired to clarify the size of foreign particles allowed to exist in the image display panel and to design the manufacturing process based on the size.

  It is an object of the present invention to provide an image display device that suppresses discharge of the image display device by solving these problems, has a good yield, and has high reliability.

The image display apparatus of the present invention is a means for solving the above-described problems.
A rear plate having at least an electron beam source;
A face plate having a phosphor that emits light by electron beam irradiation and an anode electrode for applying an electron acceleration voltage;
An envelope for vacuum-tightening the rear plate and the face plate;
In the image display device in which the inside is kept in vacuum,
The image display device is characterized in that no foreign particles of 10 μm or more are present in the vacuum-tight region.

  Here, the average electric field strength is a value obtained by dividing the anode voltage (the difference between the potential of the anode electrode and the rear plate potential) by the average distance between the face plate and the rear plate. The degree of vacuum in the image display panel is set to 1.0 [Pa] or less, which is sufficiently lower than the degree of vacuum (Paschen minimum) at which the mean free path is sufficiently long and the discharge voltage is the lowest according to Paschen's law.

  Further, the foreign particles here are defined as follows.

  <Shape> The shape is not limited to a spherical shape, but refers to any shape such as granular, flaky, flaky, or microcrystalline. Discharge due to foreign particles is necessary for discharging because particles are detached from the member by electrostatic force, accelerated by the interelectrode voltage, and collide with the counter electrode to cause destruction. It becomes. Accordingly, the foreign particles referred to here do not include those fixed (not attached) to the image display panel constituting member (eg, a structure (electrode or the like) on the rear plate), and are assumed to be movable.

  <Size> The size is defined as the size of the particle with the longest part of the particle diameter (in the case of an elongated shape, the length of the longitudinal diameter is the size).

  <Material> The material is not limited as long as it is movable. For example, a part of the member that falls off and becomes movable is regarded as a foreign particle.

  In the image display device of the present invention, the anode voltage applied to the anode electrode is 7 kV or more.

  In the image display device of the present invention, an average interval between the rear plate and the face plate is 2 mm or less.

  The image display device of the present invention is characterized in that the image display device includes an atmospheric pressure-resistant support structure (spacer).

  The image display device of the present invention is characterized in that the face plate of the image display device includes a metal back.

Moreover, the image display device of the present invention includes:
A rear plate having at least an electron beam source;
A face plate having a phosphor that emits light by electron beam irradiation and an anode electrode for applying an electron acceleration voltage;
An envelope for vacuum-tightening the rear plate and the face plate;
In the image display device in which the inside is kept in vacuum,
The image display device is characterized in that no foreign particles having a size of 3 μm or more exist in the vacuum-tight region.

  The image display device of the present invention is characterized in that in the image display device, the electron beam source is a surface conduction electron-emitting device.

[Action]
As described above, the image display device of the present invention can eliminate the occurrence of discharge due to foreign particles because there are no foreign particles having a size of 10 μm or more in the vacuum-tight region of the image display device. A display device can be obtained.

  This can be explained as follows.

  Discharge due to foreign particles is charged when the foreign particles are charged by the electric field in the image display panel and are subjected to Coulomb force, so that the foreign particles are accelerated to obtain energy and collide with the counter substrate, and the electrodes and particles are heated. To go.

  Here, when the particle size (radius) of the spherical particles is r, and the voltage between the gaps sandwiched between the parallel plate electrodes is V / electric field is E (E = V / d where the gap is d), the particles The charged charge amount q (absolute value) is expressed by the following formula 1.

  Here, ε is the dielectric constant of the medium (here, vacuum). The amount of charge induced is negative when the particles are attached to the cathode side, and is positive when the particles are attached to the anode side. For this reason, the charged foreign particles are approximately subjected to the following force F in the direction toward the counter substrate, and by this force F, the particles obtain energy from the electric field and store kinetic energy (Formula 2).

  Since the kinetic energy that is stored by the time a particle flies from one electrode to the other electrode is equal to the potential energy that is about to come out,

(Equation 3)

  Therefore, the energy and charge amount obtained by the particles depend on the voltage V and the particle radius r, and the energy and charge amount of the particles increase as the voltage V increases / the particle radius r increases. From these facts, it is predicted that the discharge by the foreign particles depends on the voltage V and the foreign particle radius r.

  The dependence of the electric field strength upon discharge in the discharge caused by foreign particles on the particle size (diameter) of the discharge decreases as the particle size increases. As a result of further intensive studies, the inventors have found that parameters such as the electrode material used (rear plate and face plate), the electrode dimensions, the amount of particles dispersed, and the usage time are related to the discharge due to foreign particles, In a state close to an actual image display panel, the particle size (diameter) dependence of the electric field strength at the time of discharge in the discharge with foreign particles was obtained (shown in FIG. 1).

  As can be seen from FIG. 1, when the average electric field strength is 1 × 10 ^ 6 [V / m], discharge is not caused by the presence of foreign particles of 10 μm or more in the vacuum-tight region of the image display device. A highly reliable image display device that does not occur can be obtained.

  In addition, the image display device as described above emits light by irradiating a phosphor with an electron beam accelerated by a voltage, but the phosphor generally has higher luminous efficiency when the acceleration voltage is higher (in the region of about 30 kV). Since it has a tendency, high acceleration voltage is required for high brightness. Here, as can be seen from Equation 3, the energy of the particles is not only the electric field strength, but also depends on the acceleration voltage. Therefore, in an image display device in which the anode voltage applied to the anode electrode is 7 kV or more, by eliminating the presence of foreign particles of 10 μm or more, high luminance is obtained and at the same time, no discharge occurs and a highly reliable image. A display device can be obtained.

  Further, the image display device is required to be thin, but if the gap of the display panel is reduced, the electric field strength is increased. Accordingly, in the image display device in which the average distance between the rear plate and the face plate is 2 mm or less, the presence of foreign particles of 10 μm or more can be reduced, and the display panel can be made thin and at the same time, no discharge is generated and the reliability is reduced. High image display device can be obtained.

  Further, if the area of the image display panel is increased in order to measure the size of the image display device, the atmospheric pressure applied to the image display panel increases. Therefore, the image display panel needs an atmospheric pressure resistant support structure (spacer). In such a large-sized image display device, since foreign matter is easily mixed and difficult to remove, discharge due to the foreign matter becomes a further problem.

  Also, a metal back (mainly made of aluminum and a thin film of 1 μm or less) known in the field of CRT may be used for the face plate of the image display device. This is because the phosphor emits light in all directions, and the light emitted backward (rear plate side) is reflected by the metal film and extracted forward (observer, user) side to improve the luminous efficiency and at the same time the anode electrode It plays a role. Here, the metal back often uses a thin film (1 μm or less) of aluminum. In addition, the metal back is not in close contact with a glass substrate or the like but is partially bonded to a porous phosphor, so that the film is weak and has a small heat capacity. For this reason, in an image display device using a metal back for the anode electrode, discharge due to foreign particles is likely to occur. Therefore, by eliminating the presence of foreign particles of 10 μm or more in an image display device having a metal plate on the face plate, it is possible to obtain a high-reliability image display device with high luminance and no discharge.

  Further, in order to achieve thinning and high luminance, when the average electric field strength of the display panel is 5 × 10 6 [V / m] or more, the vacuum hermetic region of the image display device has 3 μm or more. By eliminating the presence of foreign particles, a highly reliable image display device can be obtained without discharge.

  According to the present invention, at least a rear plate having an electron beam source, a phosphor that emits light by electron beam irradiation, and a face plate having an anode electrode for applying an electron acceleration voltage, the rear plate and the face plate are evacuated. In an image display device provided with an airtight envelope and maintained in a vacuum inside, by restricting the size of foreign particles present in the vacuum airtight region of the image display device, discharge due to foreign particles is prevented. Therefore, an image display device with high yield and high reliability can be obtained.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention to those unless otherwise specified. Absent.

  The first embodiment of the present invention will be described below with reference to FIGS.

  FIG. 2 is a perspective view of the display panel used in the embodiment, and a part of the panel is cut away to show the internal structure.

  In the figure, reference numeral 1001 denotes an outer container bottom (sometimes referred to as a rear plate), 1003 denotes a side wall, and 1002 denotes a face plate, and 1001 to 1003 form an airtight container for maintaining the inside of the display panel in a vacuum. doing. Here, the interval (gap) between the rear plate 1001 and the face plate 1002 was set to 5 mm.

  Here, N × M surface conduction electron-emitting devices 1101 are formed on the rear plate 1001. (N and M are positive integers of 2 or more, and are appropriately set according to the target number of display pixels. In this embodiment, N = 240 and M = 80.) N × M The surface conduction electron-emitting devices 1101 are simply matrix-wired by M row-directional wirings 1103 and N column-directional wirings 1102. The portion constituted by 1101 to 1103 is called a multi-electron beam source.

  The face plate 1002 includes an anode electrode 1204 that encloses the phosphor film 1201, and an anode potential is supplied through the high-pressure introduction unit 1005. The high voltage take-out section is provided with a high voltage introduction terminal (not shown) on the face plate 1002 side, and is connected to a high voltage power source 1006.

  Such an image display device was manufactured by a manufacturing process described later, and a foreign particle removal process was performed as needed during the process, thereby obtaining an image display device in which foreign particles of 10 μm or more were not mixed. Here, a method for observing foreign particles in the display panel will be described later.

  When an anode voltage of 5 kV was applied to the image display device thus obtained, no discharge occurred over a long period of time, and a stable image could be displayed.

  Next, the multi electron beam source used for the display panel will be described.

  As long as the multi electron beam source used in the image display apparatus of the present invention is an electron source in which the cold cathode elements are arranged in a simple matrix or a ladder, there is no limitation on the material, shape or manufacturing method of the cold cathode elements. Therefore, for example, an electron-emitting device such as a surface conduction electron-emitting device, a field emission type (FE type) electron-emitting device, or an MIM type electron-emitting device can be used.

  However, a surface conduction electron-emitting device is particularly preferable among these cold cathode devices under a situation where a display device having a large display screen and a low price is required. Since the surface conduction electron-emitting device is relatively simple to manufacture, it is easy to increase the area and reduce the manufacturing cost. Therefore, it can be said that it is most suitable for use in a multi-electron beam source of a high-luminance and large-screen image display device.

  Next, a method for manufacturing a display panel of an image display device to which the present invention is applied will be described with reference to FIG.

(Rear plate process)
<Step R-1; foreign matter removal (1)>
The following foreign substance removal method (1) was performed on a 3 mm thick soda lime glass substrate.

  Foreign matter removal (1): In order to remove foreign matter particles adhering to the glass substrate, oil and dirt, wet cleaning was performed. As the cleaning liquid, water, an alkaline aqueous solution, an acidic aqueous solution, an organic solvent such as alcohol or ketone, and the like are used. Further, if necessary, a surfactant or the like may be added, various kinds of liquids may be mixed and used as a washing liquid, or several kinds of liquids may be sequentially used for washing. Further, the cleaning effect can be enhanced by heating the cleaning liquid and / or the glass substrate during cleaning.

<Step R-2: Formation of wiring and electrodes>
A 0.5 [μm] SiO 2 layer is formed by sputtering on the surface of the cleaned soda glass, and an element electrode 1105 of a surface conduction electron-emitting device is formed by using a sputtering film forming method and a photolithography method. The material is a laminate of Ti and Ni. The element electrode spacing was 2 [μm] (FIG. 6A).

  Subsequently, an Ag paste was printed in a predetermined shape and baked to form column-direction wirings 1102. The column direction wiring 1102 is extended to the outside of the electron source formation region and becomes an electron source driving wiring (FIG. 6B).

  Next, an insulating layer 1106 is formed by a printing method using a paste containing PbO as a main component and a glass binder. This insulates the column direction wiring 1102 from the row direction wiring 1103 described later. Note that a notch is provided in the portion of the element electrode 1105 to connect the row direction wiring 1103 and the element electrode 1105 (FIG. 6C).

  Subsequently, row direction wirings 1103 are formed on the insulating layer 1106 (FIG. 6D). The method is the same as in the case of the column direction wiring 1102.

<Step R-3; Foreign matter removal (1)>
Foreign matter removal is performed in order to remove foreign matter particles adhering to the substrate on which the device electrodes and wiring are formed. Here, foreign matter removal (1) (wet cleaning) was performed as in step R-1.

<Step R-4; Production of electron beam source>
Subsequently, a conductive film 1104 made of PdO is formed. The conductive film 1104 is formed by forming a Cr film by sputtering on a substrate (rear plate) 1001 on which row / column-direction wirings 1102 and 1103 are formed, and forming the conductive film 1104 into a shape by photolithography. Corresponding openings are formed in the Cr film. Subsequently, a solution of an organic Pd complex compound is applied and baked at 300 [° C.] in the atmosphere to form a PdO film. Then, the Cr film is removed by wet etching, and a predetermined shape is formed by lift-off. The element film 1104 is formed (FIG. 6E).

Next, the rear plate 1001 is connected to a vacuum exhaust device (not shown) and exhausted. When the pressure in the apparatus becomes 10 ⁻⁴ [Pa] or less, a forming process is performed. The forming process was performed by applying a pulse voltage having a gradually increasing peak value to the row direction wiring for each row in the row direction. In addition, the current value of the forming pulse is measured, the resistance value of the electron-emitting device is measured at the same time, and when the resistance value per element exceeds 1 [MΩ], the forming process for the row is terminated. Move on to the next line. This is repeated to complete the forming process for all rows.

Next, an activation process is performed. Prior to this treatment, the vacuum apparatus lowers the pressure to 10 ⁻⁵ [Pa] or less. Subsequently, acetone is introduced into the vacuum apparatus. The introduction amount was adjusted so that the pressure was 1.3 × 10 ⁻² [Pa]. Subsequently, a pulse voltage is applied to the row direction wiring. The row direction wiring to which a pulse is applied for each pulse is switched to the adjacent row, and the pulse is sequentially applied to each wiring in the row direction. As a result of this processing, a deposited film containing carbon as a main component is formed in the vicinity of the electron emission portion of each electron emission device, and the device current If and the emission current Ie increase. In this manner, an electron beam source 1101 of the image display device was manufactured.

<Step R-5; Foreign matter removal (2)>
In order to remove the foreign particles adhering to the rear plate 1001 from which the electron beam source 1101 was manufactured, the following foreign matter removal (2) was performed.

  Foreign matter removal (2): In order to reduce the influence on the rear plate (face plate in the face plate process described later), dry air cleaning was performed. As a dry cleaning method, a method of blowing off foreign particles by blowing high-pressure dry air was used. Here, in order to prevent the foreign particles that have been blown off from re-adhering, it is expected that a further effect will be expected if dust collecting means is provided. As a dust collecting means, it is effective to suck air simultaneously with dry air blowing, but it is not limited to this. Moreover, the effect of removing foreign matters can be further improved by superimposing ultrasonic waves on the dry air to be blown. The rear plate 1001 manufactured as described above is integrated with the face plate 1002 in a sealing step described later.

(Face plate process)
<Step F-1; Foreign matter removal (1)>
Foreign matter removal (1) (wet cleaning) was performed on a 3 mm thick soda lime glass substrate in the same manner as in the rear plate step R-1.

<Step F-2; anode electrode production>
An anode electrode 1204 was formed on the cleaned glass substrate. As the anode electrode 1204, ITO, which is a transparent conductive film, was formed by sputtering.

<Step F-3; Foreign matter removal (1)>
Foreign matter removal (1) (wet cleaning) was performed on the face plate 1002 on which the anode electrode 1204 was manufactured in the same manner as in the rear plate step R-1.

<Step F-4; Preparation of phosphor film>
Using a glass paste and a paste containing black pigment and silver particles, a matrix-like black matrix 1202 as shown in FIG. 9A was produced by a screen printing method with a thickness of 10 μm. Here, the black matrix 1202 is used for preventing color mixing of the phosphor, preventing color shift even if the beam is slightly deviated, and absorbing external light to improve image contrast. Provided. In this embodiment, the black matrix is produced by the screen printing method. However, the present invention is not limited to this, and may be produced by using, for example, a photolithography method. Further, as the material of the black matrix 1202, a glass paste, a paste containing black pigments and silver particles are used, but it is of course not limited thereto, and for example, carbon black may be used. In this embodiment, the black matrix 1202 is formed in a matrix shape as shown in FIG. 9A. However, the black matrix 1202 is not limited to this. Of course, the black matrix 1202 is not limited to this. An array (not shown) or any other array may be used.

  Next, as shown in FIG. 9 (a), the phosphors of three colors are applied to the openings of the black matrix 1202 three times for each color by screen printing using a red, blue, and green phosphor paste. Separately produced. In this embodiment, the phosphor film is produced by using the screen printing method, but it is of course not limited to this, and it may be produced by, for example, a photolithography method. The phosphor is a P22 phosphor used in the field of CRT, and is red (P22-RE3; Y2O2S: Eu3 +), blue (P22-B2; ZnS: Ag, Al), green (P22-GN4; ZnS: Although Cu, Al) is used, it is of course not limited to this, and other phosphors may be used.

<Step F-5; Foreign matter removal (2)>
In order to remove foreign particles adhering to the substrate on which the phosphor film was produced, foreign matters were removed. Here, foreign matter removal (2) (dry air cleaning) was performed in the same manner as in Step R-5. The reason why dry air cleaning is performed is to reduce the influence on the face plate 1002. The face plate 1002 manufactured as described above is integrated with the rear plate in a sealing step described later.

(Integration (sealing) process)
<Sealing process>
When assembling an airtight container, it is necessary to seal the joints of each member in order to maintain sufficient strength and airtightness. For example, frit glass is applied to the joints, and in the air or in a nitrogen atmosphere, Celsius. Sealing was achieved by baking at 400 to 500 degrees for 10 minutes or more. A method for evacuating the inside of the hermetic container will be described later.

  Further, in order to evacuate the inside of the hermetic container to a vacuum, after assembling the hermetic container, an exhaust pipe (not shown) and a vacuum pump are connected, and the inside of the hermetic container is reduced to a degree of vacuum of about 10 to the fifth power [Pa]. Exhaust. Thereafter, the exhaust pipe is sealed. In order to maintain the degree of vacuum in the hermetic container, a getter film (not shown) is formed at a predetermined position in the hermetic container immediately before or after sealing. The getter film is, for example, a film formed by heating and vapor-depositing a getter material mainly composed of Ba by a heater or high-frequency heating, and the inside of the hermetic container is 1 × 10 minus 3 to 1 or 1 by the adsorption action of the getter film. The degree of vacuum is maintained at x10 minus 5 [Pa].

  Next, a method for observing foreign particles present in the image display apparatus will be described.

<Observation Method 1 of Foreign Particles; Observation by Optical Microscope>
The most reliable method for observing the foreign particles in the image display panel is to observe the surface of the panel member with an optical microscope. The following three types were observed.
(1) Observe each member immediately before the integration step (2) Disassemble the image display panel after the integration step and observe each member (3) Create a dummy panel without the member for the integration step, and disassemble the inner surface Observe without.

  All observation methods must be observed with great care in a clean room having a sufficiently high degree of cleanliness so that foreign particles are not mixed during observation with an optical microscope. In the method (2), foreign particles may be mixed when the image display panel is disassembled. Therefore, care must be taken not to mix foreign matters when disassembling. However, due to the structure of the image display panel, if there are any foreign particles that are mixed and generated during decomposition, the observation in (1) and the observation in (3) should be used together, and there should be no foreign particles immediately before the integration process. It was confirmed that foreign particles were not mixed or generated in the integration process, and it was clarified that there were no foreign particles in the image display panel. When observing (3), it is important to thoroughly clean the dummy panel without any members to confirm that there are no foreign particles and not to mistake the particles on the outside (atmosphere side) of the panel.

<Observation method 2 of foreign particles: Recovery of foreign particles by liquid cleaning>
As a simple method for observing foreign particles in the image display panel, the inside of the image display panel can be washed with a liquid, and the number of particles can be counted with a particle counter. The following two types were observed.
(1) Observe each member immediately before the integration step (2) Disassemble the image display panel after the integration step and observe each member.

  However, when observing the foreign particles by liquid cleaning, care must be taken that something other than the foreign particles in the panel is mixed and that the constituent members are detached by the liquid cleaning. In particular, in the method (2), it is necessary to take care not to include foreign matters generated by panel disassembly. In addition, regarding the removal of the members, special attention is required because the face plate includes those having poor adhesion to the substrate, such as phosphors and metal backs. In some cases, it is necessary to perform only observation with an optical microscope of observation method 1 There is.

  The second embodiment of the present invention will be described below with reference to FIGS. However, in the second and subsequent examples, since the same image display apparatus as that in the first example is used, only the characteristic parts in the present example will be described below.

  FIG. 4 is a perspective view of the display panel used in the example, and a part of the panel is cut away to show the internal structure.

  In the figure, reference numeral 1001 denotes an outer container bottom (sometimes referred to as a rear plate), 1003 denotes a side wall, and 1002 denotes a face plate, and 1001 to 1003 form an airtight container for maintaining the inside of the display panel in a vacuum. doing. Here, the distance (gap) between the rear plate 1001 and the face plate 1002 was set to 2 m.

  Here, N × M surface conduction electron-emitting devices 1101 are formed on the rear plate 1001 (N and M are positive integers of 2 or more, and are appropriately set according to the target number of display pixels. In this example, N = 2400 and M = 800).

  The face plate 1002 of this embodiment has a metal back 1203 containing the phosphor film 1201 as an anode electrode on the rear plate 1001 side surface of the phosphor film 1201. By having the metal back 1203 as described above, the light emission component of the phosphor film 1201 toward the rear plate 1001 can be reflected and extracted from the face plate 1002 side, so that the luminance can be improved.

  Further, since the image display apparatus of this embodiment is large in size, an atmospheric pressure resistant structure (sometimes referred to as a spacer) 1004 is required. The spacer 1004 is installed on the row direction wiring 1003 and defines the distance between the rear plate 1001 and the face plate 1002. In this embodiment, the height of the spacer 1004 is 2 mm.

  Such an image display device was manufactured by a manufacturing process described later, and a foreign particle removal process was performed as needed during the process, thereby obtaining an image display device in which foreign particles of 10 μm or more were not mixed. Here, the method for observing foreign particles in the display panel was the same as in Example 1.

  When an anode voltage of 7 kV was applied to the image display device thus obtained, no discharge occurred over a long period of time, and a stable image could be displayed.

  Next, a method for manufacturing a display panel of an image display device to which the present invention is applied will be described with reference to FIG.

(Rear plate process)
<Step R-1; foreign matter removal (1)>
<Step R-2: Formation of wiring and electrodes>
<Step R-3; Foreign matter removal (1)>
<Step R-4; Production of electron beam source>
<Step R-5; Foreign matter removal (2)>
The above steps were performed in the same manner as in Example 1 to obtain a rear plate 1001 having an electron beam source 1101.

<Process R-6; spacer fixing>
A spacer 1004 obtained by a manufacturing method described later was fixed to the rear plate 1001. The fixing method was to fix the spacer 1004 to the rear plate 1001 using an inorganic adhesive (Aron ceramic manufactured by Toagosei Co., Ltd. in this embodiment) on the rear plate 1001 side at both ends in the longitudinal direction of the spacer 1004. In the present embodiment, the spacer 1004 is fixed to the rear plate 1001 side, but of course, the present invention is not limited to this. For example, a spacer that is fixed to the face plate 1002 side or can stand independently without being fixed may be used. .

<Process R-7; Foreign matter removal (2)>
In order to remove foreign particles adhering to the rear plate 1001 to which the spacer 1004 is fixed, foreign matters were removed. Here, foreign matter removal (2) (dry air cleaning) was performed in the same manner as in Step R-5. The reason why dry air cleaning is performed is to reduce the influence on the rear plate 1001 and the spacer 1004. The rear plate 1001 and the spacer 1004 manufactured as described above are integrated with the face plate 1002 in the sealing step.

(Face plate process)
<Step F-1; Foreign matter removal (1)>
<Step F-4; Preparation of phosphor film>
<Step F-5; Foreign matter removal (2)>
The above steps were performed in the same manner as in Example 1. Since the anode electrode is a metal back 1203 shown below, it is not manufactured.

<Step F-6; metal back production>
Next, a resin intermediate film is produced by a filming process known in the field of cathode ray tubes, a metal vapor deposition film (Al in this embodiment) is produced, and finally the resin intermediate layer is thermally decomposed and removed. A metal back having a thickness of 100 nm was produced.

<Step F-7; Foreign matter removal (2)>
In order to remove foreign particles adhering to the substrate on which the phosphor film 1201 was produced, foreign matters were removed. Here, foreign matter removal (2) (dry air cleaning) was performed in the same manner as in Step R-5. The reason why dry air cleaning is performed is to reduce the influence on the face plate 1002. The face plate 1002 manufactured as described above is integrated with the rear plate 1001 in a sealing step described later.

(Spacer process)
<Step S-1; foreign matter removal (1)>
Foreign matter removal (1) (wet cleaning) was performed on the glass substrate previously polished to the size of the spacer 1004 used for the panel in the same manner as in the rear plate step R-1.

<Step S-2; high resistance film production>
The spacer 1004 has insulation sufficient to withstand a high voltage applied between the rear plate 1001 and the face plate 1002, and has conductivity sufficient to prevent charging by the electron beam emitted from the electron beam source 1101. Since this is necessary, a high resistance film (not shown) is formed on the surface of the glass substrate.

  In this embodiment, germanium and tungsten alloy nitride produced by sputtering is used as the high-resistance film. However, the present invention is not limited to this, and it is only necessary to ensure a desired antistatic function and insulation.

<Step S-3; Foreign matter removal (3)>
In order to remove foreign particles adhering to the spacer 1004 on which the high resistance film was formed, foreign matter removal (3) described below was performed.

  Foreign matter removal (3): The glass substrate used for the spacer 1004 has a thin plate thickness due to its structure. Therefore, there is a possibility that the spacer 1004 is destroyed when high pressure dry air is blown as in the foreign matter removal (2). Therefore, in order to remove the foreign particles while fixing the spacer 1004, the side of the spacer 1004 is removed by the spacer foreign matter removing means 1404 as shown in FIG. The spacer foreign matter removing means 1404 may be any means as long as it can remove the foreign matter from the spacer 1004. Here, a suction type vacuum cleaner was used, and the foreign matter was removed while fixing the spacer 1004 at the tip of the cleaner. However, the present invention is not limited to this, and a desired effect can be achieved even by a means for removing foreign matter with a roller with an adhesive, for example.

  The spacer 1004 from which foreign matter was removed in this way was fixed to the rear plate 1001 described above (step R-6; spacer fixing).

(Integration (sealing) process)
<Sealing process>
In the same manner as in Example 1, the rear plate 1001 and the face plate 1002 to which the spacers 1004 were fixed were sealed, and the inside of the image display panel was evacuated to a vacuum.

  The third embodiment of the present invention will be described below with reference to FIGS.

  The configuration of the image display panel is the same as that of Example 2, but the anode voltage was set to 10 kV for further improvement in luminance. Therefore, in the manufacturing process to be described later, a foreign matter removing step is further added as compared to Example 2 (Step R-8, Step F-8; foreign matter removing (4)), and an image in which foreign particles of 3 μm or more are not mixed. A display device was obtained.

  When an anode voltage of 10 kV was applied to the image display device thus obtained, no discharge occurred over a long period of time, and a stable image could be displayed.

(Additional process)
<Step R-8; Foreign matter removal (4)>
Foreign matter removal (4) described later was additionally performed on the rear plate 1001 to which the spacers 1004 performed in steps R-1 to R-7 were fixed.

  Foreign matter removal (4): As a cause of discharge of foreign particles in the image display panel, it is presumed that foreign particles are charged and moved by receiving Coulomb force from an electric field. Therefore, it is important to remove foreign particles that move by receiving Coulomb force. In particular, not only the alien substance but also the fallen material from the member may start to move (desorb) by an electric field, leading to a discharge.

  Therefore, before integration (sealing) of the image display device, an electric field is applied in advance to remove foreign particles (including dropping of member components). FIG. 8A shows a simplified cross section of a configuration when an electric field is applied to the rear plate 1001 to which the spacer 1004 is fixed to remove foreign particles. An electric field applying substrate 1401 having a concave portion corresponding to the spacer 1004 facing the rear plate 1001 was fixed with a constant gap g. The electric field applying substrate 1401 is provided with a voltage applying electrode 1402 on the surface opposite to the rear plate 1001, and a high voltage V is applied to the voltage applying electrode 1402 from a high voltage power source.

  The electric field application substrate 1401 is made of a high-resistance material, and the surface of the electric field application substrate 1401 on the rear plate 1001 side becomes substantially equal to the potential V after a certain time. For this reason, an electric field V / g [V / m] is applied between the rear plate 1001 and the electric field applying substrate 1401, and a constituent member that is detached due to foreign particles adhering to the rear plate 1001 or an electric field is formed. Then, it can be made to fly to the electric field applying substrate 1401 side. The foreign particles flying to the electric field application substrate 1401 side can hardly receive a new charge when adhering to the electric field application substrate 1401 (reason; because the electric field application substrate 1401 has a high resistance). It remains attached to the electric field application substrate 1401.

  In addition, since the electric field applying substrate 1401 is made of a high-resistance material, almost no current flows and no electric discharge occurs.

  The rear plate 1001 and the spacer 1004 from which foreign particles have been removed as described above are integrated with the face plate 1002 in the sealing step.

<Step F-8; foreign matter removal (4)>
Foreign matter removal (4) was additionally performed on the face plate 1002 that was performed from Step F-1 to Step F-7 in the same manner as in Step R-8; Foreign matter removal (4). However, as shown in FIG. 8B, since there is no spacer in the face plate 1002, the electric field applying substrate 1403 does not need a recess. The rear plate 1001 and the spacer 1004 from which foreign particles have been removed as described above are integrated with the face plate 1002 in the sealing step.

(Integration (sealing) process)
<Sealing process>
In the same manner as in Example 1, the rear plate 1001 and the face plate 1002 to which the spacers 1004 were fixed were sealed, and the inside of the image display panel was evacuated to a vacuum.

[Comparative Example 1]
In the image display panel having the same configuration as that of Example 1, it was produced without removing foreign matter during the process, and as a result of observing the foreign matter existing inside the display panel, there were 15 foreign particles having a size of 10 μm or more. .

  When an image was displayed by applying an anode voltage of 5 kV to such an image display device, a discharge occurred and a defect occurred in a part of the display image.

[Comparative Example 2]
In the image display panel having the same configuration as that of Example 3, it was produced without removing various foreign substances in the process, and as a result of observing the foreign substances existing inside the display panel, there were 7 foreign particles of 3 μm or more. did.

  When an image was displayed by applying an anode voltage of 10 kV to such an image display device, a discharge occurred and a defect occurred in a part of the display image.

Diagram showing the particle size dependence of the discharge voltage due to foreign particles 1 is a schematic perspective view showing an image display device according to a first embodiment of the present invention with a part cut away. The figure which shows the process flow which shows the image display apparatus manufacturing method of 1st Example of this invention. FIG. 6 is a schematic perspective view showing the image display device according to the second embodiment of the present invention, with a part cut away. The figure which shows the process flow which shows the image display apparatus manufacturing method of 2nd Example of this invention. 1 is a schematic plan view showing an electron beam source according to a first embodiment of the present invention. Schematic sectional view showing foreign matter removal (3) of the second embodiment of the present invention Schematic sectional view showing foreign matter removal (4) of the third embodiment of the present invention Schematic plan view showing the phosphor arrangement of the faceplate of the display panel The perspective view which notches and shows a part of display panel of the conventional image display apparatus Schematic cross section of image display panel

Explanation of symbols

1001 Rear plate (outer container bottom)
1002 Face plate 1003 Side wall 1004 Atmospheric pressure support structure (spacer)
1005 High-voltage introduction unit 1006 High-voltage power supply 1101 Electron beam source (surface conduction electron-emitting device)
1102 Column-direction wiring 1103 Row-direction wiring 1104 Conductive film ((surface conduction electron emission) element film)
1105 Element electrode 1106 Insulating layer 1201 Phosphor film 1202 Black matrix 1203 Metal back 1204 Anode electrode 1401 Electric field application substrate 1402 Voltage application electrode 1403 Electric field application substrate 1404 Spacer foreign matter removing means

Claims (7)

A rear plate having at least an electron beam source;
A face plate having a phosphor that emits light by electron beam irradiation and an anode electrode for applying an electron acceleration voltage;
An envelope for vacuum-tightening the rear plate and the face plate;
In the image display device in which the inside is kept in vacuum,
An image display device characterized in that no foreign particles of 10 μm or more are present in a vacuum-tight region of the image display device.   The image display device according to claim 1, wherein an anode voltage applied to the anode electrode is 7 kV or more.   The image display device according to claim 1, wherein an average interval between the rear plate and the face plate is 2 mm or less. A rear plate having at least an electron beam source;
A face plate having a phosphor that emits light by electron beam irradiation and an anode electrode for applying an electron acceleration voltage;
An envelope for vacuum-tightening the rear plate and the face plate;
In the image display device in which the inside is kept in vacuum,
An image display device characterized in that no foreign particles of 3 μm or more are present in the vacuum-tight region of the image display device.   The image display apparatus according to claim 1, wherein the image display apparatus includes an atmospheric pressure resistant support structure (spacer).   The image display device according to claim 1, wherein the face plate of the image display device includes a metal back.   7. The image display device according to claim 1, wherein the electron beam source is a surface conduction electron-emitting device.