Saturday, April 12, 2008

Sony-FET nano-Spindt emitters

These US patents describe these nano-Spindt emitters and CNTs are a preferred emitter tip.

Results of Search in US Patent Collection db for:
((carbon-nanotube AND cone) AND Sony)
: 3 patents.
Hits 1 through 3 out of 3





PAT. NO.
Title
1 7,329,978 Full-Text Cold cathode field emission display
2 7,297,469 Full-Text Method of patterning a thick-film paste material layer, method of manufacturing cold- cathode field emission device, and method of manufacturing a cold-cathode field emission display
3 7,064,493 Full-Text Cold cathode electric field electron emission display device

In 1:
In the plane-type field emission device, as a material for constituting an electron-emitting portion, particularly, carbon is preferred. More specifically, diamond, graphite and a carbon-nanotube structure are preferred. When the electron-emitting portion is made of diamond, graphite or the carbon-nanotube structure, an emitted-electron current density necessary for the display can be obtained at an electric field intensity of 5.times.10.sup.7 V/m or lower. Further, since diamond is an electric resister, emitted-electron currents obtained from the electron-emitting portions can be brought into uniform currents, and the fluctuation of brightness can be suppressed when such field emission devices are incorporated into the display. Further, since the above materials exhibit remarkably high durability against sputtering by ions of residual gas in the display, field emission devices having a longer lifetime can be attained.

Specifically, the carbon-nanotube structure includes a carbon-nanotube and/or a carbon-nanofiber. More specifically, the electron-emitting portion may be constituted of a carbon-nanotube, it may be constituted of a carbon-nanofiber, or it may be constituted of a mixture of a carbon-nanotube with a carbon-nanofiber. Macroscopically, the carbon-nanotube and carbon-nanofiber may have the form of a powder or a thin film. The carbon-nanotube structure may have the form of a cone in some cases. The carbon-nanotube and carbon-nanofiber can be produced or formed by a known PVD method as an arc discharge method and a laser abrasion method; and any one of various CVD methods such as a plasma CVD method, a laser CVD method, a thermal CVD method, a gaseous phase synthetic method and a gaseous phase growth method.

The plane-type field emission device can be produced by a method in which a dispersion of a carbon-nanotube structure in a binder material is, for example, applied onto a desired region of the cathode electrode and the binder material is fired or cured (more specifically, a method in which the carbon-nanotube structure is dispersed in an organic binder material such as an epoxy resin or an acrylic resin or an inorganic binder material such as water glass or silver paste and the like, the dispersion is, for example, applied onto a desired region of the cathode electrode, then, the solvent is removed and the binder material is fired and cured). The above method will be referred to as "first forming method of a carbon-nanotube structure". The application method includes, for example, a screen printing method.

Alternatively, the plane-type field emission device can be produced by a method in which a dispersion of the carbon-nanotube structure in a metal compound solution is applied onto the cathode electrode and then, the metal compound is fired, whereby the carbon-nanotube structure is fixed to the surface of the cathode electrode with a matrix containing metal atoms derived from the metal compound. The above method will be referred to as "second forming method of a carbon-nanotube structure". The matrix is preferably made of an electrically conductive metal oxide. More specifically, it is preferably made of tin oxide, indium oxide, indium-tin oxide, zinc oxide, antimony oxide or antimony-tin oxide. After the firing, there can be obtained a state where part of each carbon-nanotube structure is embedded in the matrix, or there can be obtained a state where the entire portion of each carbon-nanotube structure is embedded in the matrix. The matrix preferably has a volume resistivity of 1.times.10.sup.-9 .OMEGA.m to 5.times.10.sup.-6 .OMEGA.m.

In 2:
In the manufacturing method of the present invention, the material which has the function of emitting electrons and is included in the thick-film-paste-material layer, may include a carbon-nanotube structure. In this case, specifically, the carbon-nanotube structure includes a carbon-nanotube and a carbon-nanofiber. More specifically, the electron-emitting portion may be constituted of carbon-nanotubes, it may be constituted of carbon-nanofibers, or it may be constituted of a mixture of carbon-nanotubes with carbon-nanofibers. Macroscopically, the carbon-nanotube and carbon-nanofiber may have the form of a powder or a thin film. The carbon-nanotube structure constituted of the carbon-nanotube and carbon-nanofiber can be produced or formed by a known PVD method as an arc discharge method and a laser abrasion method; and any one of various CVD methods such as a plasma CVD method, a laser CVD method, a thermal CVD method, a gaseous phase synthetic method and a gaseous phase growth method.

In3:
n the plane-type field emission device, carbon is preferred as a material for constituting an electron-emitting portion. More specifically, diamond, graphite and a carbon-nanotube structure are preferred. When the electron-emitting portion is made of diamond, graphite or the carbon-nanotube structure, an emitted-electron current density necessary for the cold cathode field emission display can be obtained at an electric field intensity of 5.times.10.sup.7 V/m or lower. Further, since diamond is an electric resister, emitted-electron currents obtained from the electron-emitting portions can be brought into uniform currents, and the fluctuation of luminescence efficiency can be suppressed when such field emission devices are incorporated into the display. Further, since the above materials exhibit remarkably high durability against sputtering by ions of residual gas in the cold cathode field emission display, field emission devices having a longer lifetime can be attained.

Specifically, the carbon-nanotube structure includes a carbon-nanotube and a carbon-nanofiber. More specifically, the electron-emitting portion may be constituted of a carbon-nanotube, it may be constituted of a carbon-nanofiber, or it may be constituted of a mixture of a carbon-nanotube with a carbon-nanofiber. Macroscopically, the carbon-nanotube and carbon-nanofiber may have the form of a powder or a thin film. The carbon-nanotube structure may have the form of a cone in some cases. The carbon-nanotube and carbon-nanofiber can be produced or formed by a known PVD method as an arc discharge method and a laser abrasion method; and any one of various CVD methods such as a plasma CVD method, a laser CVD method, a thermal CVD method, a gaseous phase synthetic method and a gaseous phase growth method.

The plane-type field emission device can be produced by a method in which a dispersion of a carbon-nanotube structure in a binder material is, for example, applied onto a desired region of the cathode electrode and the binder material is fired or cured. More specifically, the plane-type field emission device can be produced by a method in which the carbon-nanotube structure is dispersed in an organic binder material, such as an epoxy resin or an acrylic resin, or an inorganic binder material, such as water glass or silver paste and the like, the dispersion is, for example, applied onto a desired region of the cathode electrode, then, the solvent is removed and the binder material is fired and cured. The above method will be referred to as a "first forming method of a carbon-nanotube structure". The application method includes, for example, a screen printing method.

Alternatively, the plane-type field emission device can be produced by a method in which a dispersion of the carbon-nanotube structure in a metal compound solution is applied onto the cathode electrode and then, the metal compound is fired, whereby the carbon-nanotube structure is fixed to the surface of the cathode electrode with a matrix containing metal atoms derived from the metal compound. The above method will be referred to as a "second forming method of a carbon-nanotube structure". The matrix is preferably made of an electrically conductive metal oxide. More specifically, it is preferably made of tin oxide, indium oxide, indium-tin oxide, zinc oxide, antimony oxide or antimony-tin oxide. After the firing, there can be obtained a state where part of each carbon-nanotube structure is embedded in the matrix, or there can be obtained a state where the entire portion of each carbon-nanotube is embedded in the matrix. The matrix preferably has a volume resistivity of 1.times.10.sup.-9 .OMEGA.m to 5.times.10.sup.-6 .OMEGA.m.

The metal compound for constituting the metal compound solution includes, for example, an organometal compound, an organic acid metal compound and metal salts (for example, chloride, nitrate and acetate). The organic acid metal compound solution is, for example, a solution prepared by dissolving an organic tin compound, an organic indium compound, an organic zinc compound or an organic antimony compound in an acid (for example, hydrochloric acid, nitric acid or sulfuric acid) and diluting the resultant solution with an organic solvent (for example, toluene, butyl acetate or isopropyl alcohol). Further, the organic metal compound solution is, for example, a solution prepared by dissolving an organic tin compound, an organic indium compound, an organic zinc compound or an organic antimony compound in an organic solvent (for example, toluene, butyl acetate or isopropyl alcohol). When the amount of the solution is 100 parts by weight, the solution preferably has a composition containing 0.001 to 20 parts by weight of the carbon-nanotube structure and 0.1 to 10 parts by weight of the metal compound. The solution may contain a dispersing agent and a surfactant. From the viewpoint of increasing the thickness of the matrix, an additive such as carbon black or the like may be added to the metal compound solution. In some cases, the organic solvent may be replaced with water.

The method for applying onto the cathode electrode the metal compound solution in which the carbon-nanotube structure is dispersed includes a spray method, a spin coating method, a dipping method, a die quarter method and a screen printing method. Of these, a spray method is preferred in view of its easiness in application.

There may be employed a constitution in which the metal compound solution in which the carbon-nanotube structure is dispersed is applied onto the cathode electrode, the metal compound solution is dried to form a metal compound layer, then, an unnecessary portion of the metal compound layer on the cathode electrode is removed, and then the metal compound is fired. Alternatively, an unnecessary portion of the metal compound layer on the cathode electrode may be removed after the metal compound is fired. Alternatively, the metal compound solution may be applied only onto a desired region of the cathode electrode.

Link

It's pretty clear to me that CNTs are an important part of these nano-Spindt emitters being shown by Sony-FET, lately.>>>>>>>>>See YouTube video here

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