JP2005116417A - Manufacturing method of field emission cold-cathode device, field emission cold-cathode device, light-emitting device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a field emission cold-cathode device entirely in self-alignment without the use of an exposure mask. <P>SOLUTION: A transparent cathode 12 is formed on a transparent substrate 30, on the surface of which a number of opaque particles are loaded in a dispersed state. The particles are heated and flattened to form a dispersal mask. An insulating layer 38 made of a negative photosensitive insulating material is formed on a whole surface, and the substrate 30 is exposed from the rear face and developed to leave the insulating layer 38 at a place where the dispersal mask does not exist. After a conductive film 42 is formed on the whole surface, the dispersal mask is removed to leave the conductive film 42 on the insulating layer 38. A positive photo-resist layer is formed on the whole surface, and the substrate 30 is exposed from the rear face and developed to leave the photo-resist layer on the conductive film 42. A carbon nanotube layer is formed on the whole surface, and the photo-resist layer is removed to leave the carbon nanotube layer 48 at the bottom of an opening 40 of the insulating layer 38. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a field emission cold cathode device using carbon nanotubes as an electron emission material and a method for manufacturing the same, and further relates to a light emitting device and a display device including such a cold cathode.

  Carbon nanotubes are excellent as an electron emission material, and many field emission cold cathode devices using the carbon nanotube have been developed. By combining such a cold cathode device and an anode coated with fluorescence, a light emitting device can be obtained, which can be used as a lighting device or a display device. FIG. 1 shows the principle of such a light emitting device. A cathode 12 is formed on the cathode substrate 10, and a carbon nanotube layer 14 is formed on the cathode 12. Above the cathode 12 is a lead grid 16, which is separated from the cathode 12 by an insulating layer 18. An anode 22 is formed on the anode substrate 20, and a phosphor 24 is applied on the anode 22.

  When a positive voltage (extraction voltage) is applied to the extraction grid 16 with respect to the cathode 12, electrons 15 are emitted from the carbon nanotube layer 14. Further, when a positive voltage (acceleration voltage) is applied to the anode 22 with respect to the extraction grid 16, the emitted electrons 15 collide with the phosphor 24, and light 26 is generated therefrom, and is transmitted through the transparent anode substrate 20. Go outside.

  A properly formed carbon nanotube has an electron emission starting electric field of about 4 V / μm. If the distance between the carbon nanotube layer 14 and the extraction grid 16 (hereinafter referred to as the grid distance) is set to 10 μm, electron emission becomes possible if the voltage of the extraction grid 16 is set to +40 V or more with respect to the cathode 12. In terms of device design, the lower the grid voltage, the better. Therefore, efforts are made to make the grid distance as small as possible. However, it is difficult to keep the lead grid 16 away from the carbon nanotube layer 14 at a distance of about 10 μm over a large area due to warpage or undulation of the substrate material or electrode metal material. Therefore, the grid distance is set to 50 to 200 μm. In this case, assuming that the cathode potential is 0 V, the grid potential is 200 to 800 V, and the anode potential is several kV.

In view of this, a technique in which a lead grid is formed on the surface of an insulating layer is known as a method for maintaining the grid distance at a small constant value over a large area. In this case, an opening for electron emission is formed in the insulating layer, and the carbon nanotube is exposed at the bottom of the opening. Such conventional techniques are disclosed in the following Patent Document 1, Patent Document 2, and Patent Document 3.
JP 2002-140979 A JP 2001-143602 A Japanese Patent Laid-Open No. 2002-245928

  In Example 5 of Patent Document 1, a cathode and carbon nanotubes are formed on a substrate, and a photosensitive insulating layer (for example, photosensitive polyimide) is formed thereon. After an opening is formed in this insulating layer, a lead grid is formed on the surface of the insulating layer. Carbon nanotubes are exposed at the bottom of the opening formed in the insulating layer. In order to form the opening in the insulating layer, a photosensitive resin exposure / development process is used. In order to form an opening with a desired size at a desired position in the insulating layer, an exposure mask having a predetermined pattern is used.

  In Patent Document 2, a cathode and an electron-emitting material (for example, carbon nanotube) are formed on a substrate and patterned using photolithography. On top of that, a photosensitive insulating layer and a photosensitive conductive film are formed in sequence, and these are exposed and developed at the same time, thereby forming an opening in the insulating layer and the conductive film where electron emission material exists. Yes. As a result, a lead grid (conductive film) is formed on the insulating layer, and the electron emission material is exposed at the bottom of the opening. In order to form openings in the insulating layer and the conductive film, an exposure mask having a predetermined pattern is used.

  In Patent Document 3, first, a transparent electrode is formed on a transparent substrate and patterned. Next, after forming a chromium film on the entire surface, the chromium film is patterned so that the chromium film remains only on the transparent electrode. At that time, an opening is formed in the center of the chromium film. Next, after an aluminum film is formed on the entire surface, the aluminum film is patterned in a dot shape so as to cover the central opening of the chromium film. Next, a negative photosensitive insulator is coated on the entire surface, exposed from the back side of the transparent substrate, and developed. Since the chromium film and the aluminum film serve as a mask, the insulating layer remains only in the region where the chromium film and the aluminum film are not formed. Next, a conductive photosensitive paste is applied to the entire surface and exposed from the back side of the transparent substrate, whereby a conductive film is formed only on the insulating layer. This becomes a lead electrode. Next, the dot-like aluminum film is removed using an etching solution, and the opening is exposed at the center of the chromium film. Next, negative photosensitive carbon nanotubes are coated on the entire surface, exposed from the back side of the transparent substrate, and developed. As a result, the carbon nanotubes on the chromium film and the extraction electrode are removed, and the carbon nanotubes remain only at the central opening of the chromium film. Also in this prior art, for example, an exposure mask is required when patterning the chromium film described above.

  According to the three prior arts described above, the lead-out electrode is provided on the surface of the insulating layer, and the carbon nanotube is exposed at the bottom of the opening of the insulating layer, thereby maintaining the lead-out distance at a small constant value over a large area. I can do it now. However, at least one exposure mask for patterning is required. Therefore, an expensive mask aligner used in the semiconductor manufacturing process is required.

  An object of the present invention is to provide a field emission cold cathode device and a method for manufacturing the same, which can be manufactured entirely in a self-aligned manner without using an exposure mask. Moreover, it is providing the light-emitting device and display apparatus provided with such a cold cathode apparatus.

  The present invention includes the following steps in a method of manufacturing a field emission cold cathode device. (A) A step of forming a transparent cathode on the first surface of the transparent substrate. (A) A step of placing a large number of particles opaque to ultraviolet light on the surface of the cathode in a dispersed state and partially covering the surface of the cathode. (C) A step of heating the particles to flatten the particles to form a dispersion mask, and closely attaching the dispersion mask to the cathode. (D) A step of forming an insulating layer made of a negative photosensitive insulating material on the surface of the cathode in a state where the dispersion mask is in close contact therewith. (E) A step of exposing the insulating layer by irradiating light from a side of the second surface opposite to the first surface of the substrate. (F) developing the insulating layer, removing the insulating layer present on the dispersion mask, and leaving the insulating layer in a place where the dispersion mask does not exist; (G) forming a conductive film on the surface of the insulating layer and the exposed surface of the dispersion mask; (G) removing the dispersion mask, removing the conductive film existing on the dispersion mask, leaving the conductive film on the insulating layer, and exposing a part of the surface of the cathode; . (G) forming a positive photoresist layer on the surface of the conductive film and the exposed surface of the cathode; (Ko) exposing the photoresist layer by irradiating light from the second surface side of the substrate; (Sa) Developing the photoresist layer, removing the photoresist layer where the conductive film does not exist, leaving the photoresist layer on the conductive film, and forming a part of the surface of the cathode The stage to expose. (F) forming a carbon nanotube layer on the surface of the photoresist layer and the exposed surface of the cathode; (S) The photoresist layer is removed, the carbon nanotube layer existing on the photoresist layer is also removed, and the carbon nanotube layer is left on the surface of the cathode where the insulating layer does not exist. Stage.

  In the cold cathode device manufactured by this manufacturing method, a conductive film exists at a position separated from the carbon nanotube layer by the thickness of the insulating layer, and this conductive film becomes a lead grid. When viewed from above, the openings are randomly formed in the drawer grid, and the carbon nanotube layer is exposed at the bottom of the openings. The position of the opening is the position where the dispersion mask is first placed on the cathode.

  The negative photosensitive insulating material in the step (d) is preferably a photosensitive polyimide. Photosensitive polyimide has heat resistance, and the effect of degassing is negligible even when used in vacuum. The material of the particles in the step (a) is preferably a thermoplastic resin that is opaque to ultraviolet light (wavelength in the range of about 300 to 370 nm) used for exposure of the photosensitive insulating material. For example, polystyrene. Further, the average size of the particles is preferably in the range of 0.5 to 2.0 μm.

  The field emission cold cathode device of the present invention is manufactured by the above-described manufacturing method. Furthermore, the light emitting device of the present invention includes a cold cathode unit including such a cold cathode device and an anode unit facing the cold cathode unit. Furthermore, the display device of the present invention includes a cold cathode unit including such a cold cathode device, and an anode unit facing the cold cathode unit, and a plurality of pixels in which the anode units are arranged in a matrix. An electrode is provided.

  By using the manufacturing method described above, a field emission cold cathode device can be manufactured in a self-aligned manner without using an exposure mask. Therefore, expensive manufacturing equipment such as a mask aligner is not required.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. 2 to 4 are cross-sectional views schematically showing steps A to J of an embodiment of the method for manufacturing a field emission cold cathode device according to the present invention.

  In step A of FIG. 2, a transparent cathode 32 made of an ITO film is formed on the first surface 31 (upper surface in the drawing) of the transparent glass substrate 30. A normal cleaning process is performed on the surface of the cathode 32. A large number of polystyrene particles 34 having an average size of about 1 μm are electrodeposited on the surface of the cathode 32 in a dispersed state. The average size of polystyrene is preferably in the range of about 0.5 to 2.0 μm. Polystyrene is opaque to ultraviolet light (about 365 nm) used in the photosensitive polyimide exposure process described below. The particles 34 are dispersed by individual electric charges and adhere randomly. In rare cases, the particles 34 may contact each other, but there is no particular inconvenience. Since the dispersion density of the particles 34 is substantially proportional to the time and current of the electrodeposition process, the dispersion density can be adjusted by controlling this. It is appropriate that the average distance between the particles is a dispersion density of about 5 to 10 μm. Assuming that the average distance is 10 μm, the number of particles is 1 million per square centimeter. Instead of polystyrene, other thermoplastic resins that are opaque to ultraviolet light (wavelength in the range of about 300 to 370 nm) may be used.

  Next, in step B, the substrate 30 is heated to about 200.degree. The particles are softened and flattened to form a substantially circular plate 36 that is in close contact with the cathode 32. Since this disc 36 serves as a mask in the exposure process described later, it will be referred to as a dispersion mask hereinafter. By flattening the 1 μm particles, the size of the dispersion mask 36 becomes about 1.5 μm.

  Next, in step C, an insulating layer 38 made of negative photosensitive polyimide is applied to the thickness of 10 μm on the entire surface of the cathode 32 on which the dispersion mask 36 is formed, using a spin coater. Then, the insulating layer 38 is exposed by irradiating light 35 from the second surface 33 (surface opposite to the first surface 31, that is, the lower surface in the drawing) of the substrate 30.

  Next, in step D, the insulating layer 38 is developed. Since the portion of the insulating layer 38 existing on the opaque dispersion mask 36 does not receive the light 35, this portion of the insulating layer 38 is removed by development. The insulating layer 38 in the region where the dispersion mask 36 is not present remains as it is even after development because it is exposed to the light 35. Accordingly, an opening 40 is formed above the dispersion mask 36. Thereafter, the insulating layer 38 is heated and cured.

  Next, in step E of FIG. 3, a conductive film 42 made of aluminum is formed on the entire surface on the first surface side of the substrate 30 by vapor deposition. The film thickness is suitably about 1 μm. The conductive film 42 is deposited on the insulating layer 38 and on the dispersion mask 36 exposed at the bottom of the opening 40.

  Next, in Step F, the dispersion mask 36 made of polystyrene (see Step E) is dissolved and removed using an organic solvent such as acetone. At the same time, the conductive film on the dispersion mask is also removed. Thereby, a state in which the conductive film 42 is formed on the insulating layer 38 in which the opening 40 is formed is obtained. The cathode 32 is exposed at the bottom of the opening 40.

  Next, in Step G, a positive photoresist 44 is applied to the entire surface on the first surface side of the substrate 30 using a spin coater. Then, light 46 is irradiated from the second surface 33 side of the substrate 30 to expose the photoresist 44.

  Next, in step H, the photoresist 44 is developed. Since the light 46 does not strike the portion of the photoresist 44 existing on the opaque conductive film 42, the photoresist 44 in this portion remains even if it is developed. Since the light 46 hits the photoresist 44 in the region where the conductive film 42 does not exist, this portion of the photoresist 44 is removed by development.

  Next, in step I of FIG. 4, the surface of the cathode 32 exposed at the bottom of the opening 40 is cleaned by light plasma cleaning. Then, the carbon nanotube layer 48 is deposited on the entire surface on the first surface side of the substrate 30 by a low temperature CVD method or a printing method using an ink containing carbon nanotubes. The carbon nanotube layer 48 is deposited on the photoresist 44 and on the cathode 32 exposed at the bottom of the opening 40.

  Next, in Step J, when the photoresist 44 (see Step I) is removed, the carbon nanotube layer 48 on the photoresist 44 is also removed, and the carbon nanotube layer 48 is formed only on the cathode 32 exposed at the bottom of the opening 40. Remain. As a result, a state in which the carbon nanotube layer 48 is exposed at the bottom of the opening 40 of the insulating layer 38 and the conductive film 42 (which becomes a lead grid) is present on the insulating layer 38 is obtained. Since the thickness of the insulating layer 38 is about 10 μm, a cold cathode device having a grid distance of about 10 μm is obtained.

  As is apparent from the above description, no exposure mask is required to manufacture this cold cathode device. All processing can be performed by self-alignment. FIG. 5 is a perspective view schematically showing the completed cold cathode device. A part of the insulating layer 38 is notched. The cathode 12 is formed on the substrate 30, and the insulating layer 38 is on the cathode 12. Openings 40 are randomly formed in the insulating layer 38 in a dispersed state. The position of the opening 40 is a position where polystyrene particles are first dispersed and electrodeposited. The carbon nanotube layer 48 is exposed at the bottom of the opening 40. A conductive film 42 is formed on the insulating layer 38. The conductive film 42 becomes a lead grid.

  Next, the structure of a light emitting device using such a cold cathode device will be described. Such a light emitting device is useful as a light source for illumination or a backlight light source of a liquid crystal display device. In addition, if an anode unit having a large number of pixel electrodes provided with active elements such as TFTs formed in a matrix is prepared, the light emitting device described below can be a so-called active matrix display device. FIG. 6 is an exploded perspective view of the light emitting device. The cathode unit 49 and the anode unit 50 are sealed with a sealing foil 52 made of a low melting point alloy. The anode unit 50 shows a state cut at the center.

  The basic structure of the cathode unit 49 is a cold cathode device manufactured as described above. That is, a transparent cathode 32 is formed on a transparent glass cathode substrate 30, and an insulating layer and a conductive film 42 are formed thereon. The carbon nanotube layer is exposed at the bottom of the opening of the insulating layer. Inner spacers 54 are erected on the conductive film 42 at intervals of 15 mm vertically and horizontally. This interval depends on the thickness of the cathode substrate and the anode substrate. Assuming that the thickness of the cathode substrate and the anode substrate is 1 mm, it is appropriate to stand at an interval of 15 mm as described above. The height of the inner spacer 54 is about 1 to 5 mm, although it depends on the applied anode voltage. It is known that if the inner spacer 54 is formed of an insulating material, it is charged to a negative potential when it is exposed to electron impact from the cathode, and the electron trajectory toward the anode is bent. In order to avoid such a problem, the inner spacer 54 is formed of a conductive material such as semiconductor glass.

  A sealing film 56 made of a thick film of gold or silver is printed and formed on the peripheral edge of the cathode substrate 30 for firing. The formation width of the sealing film 56 is suitably about 1% of the dimension of the long side of the cathode substrate 30. The thickness of the sealing film 56 needs to be 20 μm or more after firing.

  In the anode unit 50, a frame-like glass piece is welded to the peripheral edge of a transparent glass anode substrate 58 with frit glass, and this is used as the outer peripheral spacer 60. The outer peripheral spacer 60 can also be formed by stamping. The height of the outer peripheral spacer 60 is about 1 to 5 mm which is substantially the same as that of the inner spacer 54. A sealing film 62 made of a thick film of gold or silver is printed on the surface (lower surface in the figure) of the outer peripheral spacer 60 and fired. The formation width and thickness of the sealing film 62 are the same as those of the sealing film 56 on the cathode substrate 30 side.

  A transparent anode 63 (see FIG. 10) made of an ITO film is formed on the inner surface of the anode substrate 58, and a phosphor 64 is formed thereon. The phosphor 64 can be formed by a technique such as precipitation, electrodeposition, ink jet printing, and the size of the phosphor 64 is approximately the same as the size of the opposing cathode 32.

  The frame-shaped sealing foil 52 has a melting point of 250 to 300 ° C., and its shape is the same as the end face shape of the outer peripheral spacer 60. The thickness of the sealing foil 52 is about 30 μm.

  FIG. 10 is an exploded cross-sectional view of the light-emitting device shown in FIG. The cathode substrate 30 and the outer peripheral spacer 60 of the anode substrate 58 may be sealed by the sealing film 56 on the cathode substrate 30 side, the sealing foil 52, and the sealing film 62 on the outer peripheral spacer 60 side. It is clearly shown. An anode 63 and a phosphor 64 are formed on the inner surface of the anode substrate 58.

  FIG. 7 is a perspective view of the cathode unit 49. A grid potential introducing portion 66, a first getter device 68, and an anode potential introducing portion 70 are formed along one short side of the cathode substrate 30. A cathode potential introducing portion 72, a second getter device 74, and a ground potential introducing portion 76 are formed along the other short side of the cathode substrate 30.

  FIG. 8 is an enlarged perspective view showing the vicinity of one short side of the cathode substrate 30. On the first surface 31 (upper surface in the drawing) of the cathode substrate 30, in a region between the cathode 32 and the short side, a grid lead fixing seat 78, a first getter fixing seat 80, and an anode lead fixing seat. 82 is printed with a thick film of gold or silver. An opening 84 is formed in the grid lead fixing seat 78, and the opening 84 is connected to a through hole formed in the cathode substrate 30. An opening is also formed in the anode lead fixing seat 82, and this opening is also connected to a through hole formed in the cathode substrate 30. The first nail head lead 88 is inserted into the ring foil 90 made of a low melting point alloy and then inserted into the opening 84 of the grid lead fixing seat 78 and the through hole of the cathode substrate 30. The tip of the first nail head lead 88 protrudes to the back side (lower surface side in the figure) of the cathode substrate 30. When the cathode substrate 30 is heated, the ring foil 90 is melted and the first nail head lead 88 and the grid lead fixing seat 78 are connected. One end of a bonding wire 96 (gold or aluminum wire) is connected to the grid lead fixing seat 78, and the other end is connected to the conductive film 42 (drawing grid). The tip of the first nail head lead 88 is connected to an electric circuit outside the cathode substrate 30 (the lower side of the drawing). As a result, a grid potential is applied to the conductive film 42 via the first nail head lead 88 and the bonding wire 96.

  The second nail head lead 92 is inserted into the ring foil 94 made of a low melting point alloy and the through hole of the anode contactor 98, and then the opening 86 of the anode lead fixing seat 82 and the through hole of the cathode substrate 30. Inserted into. The anode contact 98 is welded to the anode lead fixing seat 82. The upper end of the anode contactor 98 is in contact with the anode on the anode unit side. The tip of the second nail head lead 92 protrudes to the back side (lower surface side in the figure) of the cathode substrate 30. When the cathode substrate 30 is heated, the ring foil 94 is melted and the second nail head lead 92 and the anode contact 98 are connected. The tip of the second nail head lead 92 is connected to an electric circuit outside the cathode substrate 30 (the lower side in the drawing). As a result, an anode potential is applied to the anode via the second nail head lead 92 and the anode contactor 98. The first getter 100 is welded to the first getter fixing seat 80.

  FIG. 9 is an enlarged perspective view showing the vicinity of the other short side of the cathode substrate 30. In the region between the other short side and the cathode 32, a cathode lead fixing seat 102 and a second getter fixing seat 104 are formed of a thick film of gold or silver. A ground lead fixing seat 106 is formed integrally with the sealing film 56 at the periphery. The cathode lead fixing seat 102 partially overlaps the cathode 32 (see FIG. 10), and is electrically connected to the cathode 32. An opening 108 is formed in the cathode lead fixing seat 102, and this opening 108 is connected to a through hole formed in the cathode substrate 30. An opening 110 is also formed in the grounding lead fixing seat 106, and this opening 110 is also connected to a through hole formed in the cathode substrate 30. The third nail head lead 112 is inserted into the ring foil 114 made of a low melting point alloy and then inserted into the opening 108 of the cathode lead fixing seat 102 and the through hole of the cathode substrate 30. The tip of the third nail head lead 112 protrudes to the back side (lower surface side in the figure) of the cathode substrate 30. When the cathode substrate 30 is heated, the ring foil 114 is melted, and the third nail head lead 112 and the cathode lead 102 are connected. The tip of the third nail head lead 112 is connected to an electric circuit outside the cathode substrate 30 (the lower side in the drawing). As a result, a cathode potential is applied to the cathode 32 via the third nail head lead 112 and the cathode lead fixing seat 102.

  The fourth nail head lead 116 is inserted into the ring foil 118 made of a low melting point alloy and then inserted into the opening 110 of the ground lead fixing seat 106 and the through hole of the cathode substrate 30. The tip of the fourth nail head lead 116 protrudes to the back side (lower surface side in the drawing) of the cathode substrate 30. When the cathode substrate 30 is heated, the ring foil 118 is melted and the fourth nail head lead 116 and the ground lead fixing seat 106 are connected. The tip of the fourth nail head lead 116 is connected to the electric circuit outside the cathode substrate 30 (the lower side in the drawing). As a result, a ground potential is applied to the sealing film 56 at the peripheral portion via the fourth nail head lead 116 and the ground lead fixing seat 106. A second getter 120 is welded to the second getter fixing seat 104. In this light emitting device, two getters are provided in addition to the first getter described above. By providing a plurality of getters in this way, a good degree of vacuum can be maintained.

  In FIG. 10, it is clearly shown that the third nail head lead 112 penetrates the ring foil 114, the cathode lead fixing seat 102 and the cathode substrate 30. Other leads 88, 92, 116 (see FIGS. 8 and 9) also penetrate the cathode substrate 30 in the same manner.

  The four leads 88, 92, 112, and 116 (see FIGS. 8 and 9) are made of 426 alloy (42% nickel, 6% chromium, balance iron) or 48 alloy (48% nickel, balance iron). ). The diameters of the shaft portions of these leads are smaller than the through holes formed in the cathode substrate. At the head of the lead, there is a nail head larger than the through-hole formed in the cathode substrate.

  Next, an overall manufacturing procedure of the light emitting device will be described. In FIG. 6, through holes for passing four leads 88, 92, 112, 116 (see FIGS. 8 and 9) are formed in the cathode substrate 30. The diameter of the through hole is about 0.4 mm. A cathode 32 made of ITO is formed on the entire first surface of the cathode substrate 30 and etched to a predetermined cathode size. The sealing film 56 is printed on the peripheral portion of the first surface of the cathode substrate 30 and fired. Simultaneously with the printing of the sealing film 56, lead fixing seats 78, 82, 102, 106 and getter fixing seats 80, 104 (see FIGS. 8 and 9) are also formed. Next, a field emission cold cathode device is formed on the cathode 32 according to the steps shown in FIGS.

  On the other hand, an anode 63 made of ITO is formed on the first surface side of the anode substrate 58. Then, the outer peripheral spacer 60 is formed on the peripheral portion of the first surface of the anode substrate 58. A sealing film 62 is printed on the end face of the outer peripheral spacer 60 and fired. A phosphor 64 (see FIG. 10) is formed on the anode 63.

  A temporary fixing adhesive is applied to one end of the inner spacer 54, and this is placed on the conductive film 42 of the field emission cold cathode device. 8 and 9, getters 100 and 120 are laser welded to two getter fixing seats 80 and 104, respectively. An anode contact 98 is welded to the anode lead fixing seat 82. One end of a bonding wire 96 is connected to the grid lead fixing seat 78, and the other end is connected to the conductive film 42. The four leads 88, 92, 112, 116 are passed through the ring foils 90, 94, 114, 118 and then inserted into the cathode substrate 30.

  Returning to FIG. 6, the sealing foil 52 cut out in the shape of the outer peripheral spacer 60 is placed on the sealing film 56 of the cathode unit 49. Above that, the anode unit 50 is held. These are placed in a vacuum vessel and evacuated. Maintain at 250 ° C for some time to promote degassing during exhaust. Thereafter, the anode unit 50 is lowered and the sealing film 62 of the anode unit 50 is placed on the sealing foil 52. The temperature is raised to 300 ° C., the sealing foil 52 and the ring foils 90, 94, 114, 118 (see FIGS. 8 and 9) are melted, and then cooled. Thereby, the sealing between the cathode unit 49 and the anode unit 50 and the welding of the four leads 88, 92, 112, and 116 (see FIGS. 8 and 9) are completed. In addition, inside the vacuum vessel, there is an elevating device that holds the anode unit 50 so as to be able to move up and down, and the elevating device can press the anode unit 50 against the sealing foil 52 on the cathode unit 49 with an appropriate pressure. it can.

  An exhaust hole may be formed in the cathode substrate 30. In this case, the cathode unit 49 and the anode unit 50 can be heat-sealed in a reducing atmosphere, and then these are put in a vacuum vessel, and the air inside the light emitting device is evacuated through the exhaust hole. Can exhaust. After exhausting, close the exhaust hole with a patch.

  The cold cathode device of the present invention uses polyimide for the insulating layer, and this polyimide is a resin having high heat resistance, but cannot withstand an environment exceeding 380 ° C. Therefore, when manufacturing a light emitting device equipped with this cold cathode device, it is necessary to perform all processing at a temperature lower than 380 ° C. Therefore, the frit glass used in the normal flat panel display cannot be used as the sealing material. Therefore, as described above, a low melting point alloy is used as the sealing material. There are various types of low melting point alloys in terms of melting point and workability. According to experiments, Au 80% -Sn 20% gold-tin alloy showed good sealing properties. In addition, if the conditions are devised, it is considered that an inexpensive Sn80% -Au20% tin-gold alloy or silver-tin alloy can also be used. The locations using the low melting point alloy are the sealing foil 52 and the sealing films 56 and 62 in FIG. 6, and the ring foils 90, 94, 114 and 118 in FIG. 8 or FIG.

  FIG. 11 shows the operation of the light-emitting device described above. When a positive voltage (for example, 40 V) is applied to the extraction grid (conductive film) 42 with respect to the cathode 32, electrons 122 are emitted from the carbon nanotube layer 48. When a positive voltage (for example, 80 V) higher than that of the extraction grid 42 is applied to the anode 63 with respect to the cathode 32, the electrons 122 are accelerated toward the anode 63 and collide with the phosphor 64. Light 124 is emitted from the phosphor 64, which passes through the transparent anode substrate 58 and goes out. A specification example of a light emitting device using a zinc oxide phosphor as a phosphor will be described. The outer dimensions are 92 mm × 72 mm × 6 mm, the light emitting part size is 80 mm × 60 mm, the grid voltage is 40 V, the anode voltage is 80 V, and the power consumption. Is about 3 W, and the emission luminance at that time is 10,000 cd per square meter.

  Next, another example of the light emitting device will be described. FIG. 12 is a perspective view showing a part cut out. Further, the central portion in the longitudinal direction is omitted. In this light emitting device, a cylindrical cathode unit 128 is concentrically arranged inside a cylindrical anode unit 126. FIG. 13 is a longitudinal sectional view near one end (right end in FIG. 12) of the light emitting device in FIG. The anode unit 126 is obtained by forming a transparent anode 132 and a phosphor 134 on the inner surface of a large-diameter cylindrical glass tube 130. The cathode unit 128 is formed by forming a cathode 138, a carbon nanotube layer 140, an insulating layer 142, and a lead grid 144 on the outer peripheral surface of a small-diameter cylindrical glass tube 136. The structure of the cathode unit and the manufacturing method thereof are the same as those of the cold cathode device shown in FIGS. The only difference is whether the overall shape is planar or cylindrical.

  In FIG. 13, a stem 146 is formed at the end of the inner glass tube 136, and the outer peripheral surface thereof is sealed by the outer glass tube 130. Two leads 147 and 148 pass through the stem 146. The cathode lead 147 is connected to the cathode 138 through the wiring film 150 (see also FIG. 12) on the surface of the glass tube 136. The lead 148 for the lead grid is connected to the lead grid 144 via the bonding wire 152.

  In FIG. 12, an anode lead assembly 154 is fixed to the other end (left end) of the outer glass tube 130. FIG. 15 is a perspective view of the anode lead assembly 154. An anode contact body 158 is fixed to the anode lead 156 at the boss portion 160 of the anode contact body 158 by welding. The tip of the anode lead 156 passes through the boss portion 160, and a ring-shaped getter 162 is fixed to the tip by welding. The anode contact body 158 includes three contacts 164 having a divergent shape at regular intervals. The contact 164 is gently bent at the tip, and the top 166 contacts the anode on the inner surface of the outer glass tube. The anode contact body 158 is formed of a conductive material having a spring property (for example, stainless steel SUS340). The diameter of the imaginary circle passing through the top 166 of each of the three contacts 164 is slightly larger than the inner diameter of the anode. Therefore, when the top portion 166 of each contactor 164 is in electrical contact with the anode, the contactor 164 is elastically deformed slightly inward, and an appropriate contact pressure is maintained by the elastic restoring force. . The structure of the contact 164 is not limited to the three-part structure as shown in the figure, and may be another structure as long as an appropriate contact pressure can be maintained.

  A dumet wire is connected in the middle of the anode lead 156, and a glass bead 168 is provided on the outer periphery of the dumet wire. This glass bead 168 is used to seal the end of the glass tube 130 and the anode lead assembly 154, as shown in FIG.

  14 is a cross-sectional view of the light emitting device shown in FIG. Electrons 170 emitted radially from the cathode unit 128 strike the phosphor 134 of the anode unit 126, and light 172 therefrom passes through the glass tube 130 and exits radially. An example of the specification of a cylindrical light emitting device using a zinc oxide phosphor as the phosphor is described. The outer dimensions are 22 mm in diameter × 150 mm in length, the light emitting part size is 22 mm in diameter × 120 mm in length, the grid voltage is 40V, The anode voltage is 120 V, the power consumption is about 7 W, and the light emission brightness at that time is 27,000 cd per square meter.

It is a principle figure of the conventional light-emitting device. It is sectional drawing which shows the process AD about one Example of the manufacturing method of the field emission type cold cathode apparatus which concerns on this invention. FIG. 3 is a cross-sectional view showing steps E to H subsequent to FIG. 2. FIG. 4 is a cross-sectional view showing steps I and J following FIG. 3. It is a perspective view of the cold cathode apparatus manufactured at the process of FIGS. It is a disassembled perspective view of the light-emitting device using a cold cathode apparatus. It is a perspective view of a cathode unit. It is a perspective view which expands and shows the vicinity of one short side of a cathode substrate. It is a perspective view which expands and shows the vicinity of the other short side of a cathode substrate. FIG. 7 is an exploded cross-sectional view of the light emitting device shown in FIG. 6. It is a principle figure which shows operation | movement of the above-mentioned light-emitting device. It is the perspective view which notched the part about another example of the light-emitting device, and showed the inside. It is a longitudinal cross-sectional view of one edge part vicinity of the light-emitting device shown in FIG. It is a cross-sectional view of the light-emitting device shown in FIG. It is a perspective view of an anode lead assembly.

Explanation of symbols

30 Cathode substrate 31 First surface 32 Cathode 33 Second surface 34 Particle 35 Light 36 Dispersion mask 38 Insulating layer 40 Opening 42 Conductive film (drawing grid)
44 photoresist 46 light 48 carbon nanotube layer

Claims (8)

A manufacturing method of a field emission cold cathode device comprising the following steps.
(A) A step of forming a transparent cathode on the first surface of the transparent substrate.
(A) A step of placing a large number of particles opaque to ultraviolet light on the surface of the cathode in a dispersed state and partially covering the surface of the cathode.
(C) A step of heating the particles to flatten the particles to form a dispersion mask, and closely attaching the dispersion mask to the cathode.
(D) A step of forming an insulating layer made of a negative photosensitive insulating material on the surface of the cathode in a state where the dispersion mask is in close contact therewith.
(E) A step of exposing the insulating layer by irradiating light from a side of the second surface opposite to the first surface of the substrate.
(F) developing the insulating layer, removing the insulating layer present on the dispersion mask, and leaving the insulating layer in a place where the dispersion mask does not exist;
(G) forming a conductive film on the surface of the insulating layer and the exposed surface of the dispersion mask;
(G) removing the dispersion mask, removing the conductive film existing on the dispersion mask, leaving the conductive film on the insulating layer, and exposing a part of the surface of the cathode; .
(G) forming a positive photoresist layer on the surface of the conductive film and the exposed surface of the cathode;
(Co) irradiating light from the second surface side of the substrate to expose the photoresist layer;
(Sa) Developing the photoresist layer, removing the photoresist layer where the conductive film does not exist, leaving the photoresist layer on the conductive film, and forming a part of the surface of the cathode The stage to expose.
(F) forming a carbon nanotube layer on the surface of the photoresist layer and the exposed surface of the cathode;
(S) The photoresist layer is removed, the carbon nanotube layer existing on the photoresist layer is also removed, and the carbon nanotube layer is left on the surface of the cathode where the insulating layer does not exist. Stage.   2. The manufacturing method according to claim 1, wherein the negative photosensitive insulating material is photosensitive polyimide.   3. The manufacturing method according to claim 1, wherein the material of the particles is a thermoplastic resin.   The manufacturing method according to claim 3, wherein the thermoplastic resin is polystyrene.   5. The manufacturing method according to claim 3, wherein an average size of the particles is in a range of 0.5 to 2.0 [mu] m.   A field emission cold cathode device manufactured by the manufacturing method according to any one of claims 1 to 5.   A light emitting device comprising a cold cathode unit including the field emission cold cathode device according to claim 6 and an anode unit facing the cold cathode unit.   A plurality of pixel electrodes each including a cold cathode unit including the field emission cold cathode device according to claim 6 and an anode unit facing the cold cathode unit, the anode units being arranged in a matrix. A display device comprising the display device.

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