| Phosphors -> Monitor Keywords |
|
|
  PhosphorsUSPTO Application #: 20060132020Title: Phosphors Abstract: Small particles provide for improved performance as phosphors especially in the production of display devices. Particles with a diameter less than about 100 nm have altered band properties that affect the emission by the particles. A collection of such small particles with a narrow distribution around a selected average diameter can be used to produce emission at a desired frequency. These particles are effective for producing a wide variety of display types including flat panel displays. Laser pyrolysis provides an efficient process for the production of desired particles. (end of abstract) Agent: Patterson, Thuente, Skaar & Christensen, P.A. - Minneapolis, MN, US Inventors: Nobuyuki Kambe, Xiangxin Bi USPTO Applicaton #: 20060132020 - Class: 313485000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20060132020. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 08/962,362, filed Oct. 31, 1997, entitled "PHOSPORS", which is incorporated herein by reference. FIELD OF THE INVENTION [0002] The invention relates to phosphor particles that emit light at desired wavelengths following stimulation and devices made with these particles. The invention further relates to methods of producing phosphor particles. BACKGROUND OF THE INVENTION [0003] Electronic displays often use phosphor material, which emits visible light in response to interaction with electrons. Phosphor materials can be applied to substrates to produce cathode ray tubes, flat panel displays and the like. Improvements in display devices place stringent demands on the phosphor materials, for example, due to decreases in electron velocity and increases in display resolution. Electron velocity is reduced in order to reduce power demands. In particular, flat panel displays generally require phosphors responsive to low velocity electrons. [0004] In addition, a desire for color display requires the use of materials or combinations of materials that emit light at different wavelengths at positions in the display that can be selectively excited. A variety of materials have been used as phosphors. In order to obtain materials that emit at desired wavelengths of light, activators have been doped into phosphor material. Alternatively, multiple phosphors can be mixed to obtain the desired emission. Furthermore, the phosphor materials must show sufficient luminescence. SUMMARY OF THE INVENTION [0005] Small, nanoscale particles provide improved performance as phosphors. For example, particles with average diameters less than about 100 nm have altered band gaps with emission frequencies that are functions of the particle diameters. Therefore, collections of these particles with a narrow distribution of diameters can be used to provide selected emission frequencies without necessarily altering the particle composition. The small size of the particles also results in high luminescence, responsiveness to low velocity electrons as well as processing advantages. Laser pyrolysis provides an efficient method for the production of highly pure nanoscale particles with a narrow distribution of particle sizes. [0006] In a first aspect, the invention features a display device comprising phosphor particles having an average diameter selected to yield light emissions in a desirable portion of the electromagnetic spectrum following excitation and the phosphors particles having an average diameter less than about 100 nm. The phosphor particles can comprise a metal compound such as ZnO, ZnS, TiO.sub.2 and Y.sub.2O.sub.3. The phosphor particles preferably have an average diameter from about 5 nm to about 50 nm and a diameter distribution such that at least about 95 percent of the particles have a diameter greater than about 60 percent of the average diameter and less than about 140 percent of the average diameter. In certain embodiments, the excitation of the phosphors is accomplished with low velocity electrons. [0007] In another aspect, the invention features a composition for application by photolithography comprising phosphor particles and a curable polymer, the phosphor particles having an average diameter and a distribution of diameters selected to yield light emissions in a selected portion of the electromagnetic spectrum following excitation and the phosphor particles having an average diameter less than about 100 nm. The curable polymer can be curable by UV radiation or by electron beam radiation. The phosphor particles preferably have an average diameter from about 5 nm to about 50 nm. [0008] In another aspect, the invention features a method for producing zinc oxide particles comprising the step of pyrolyzing a molecular stream comprising a zinc precursor, an oxidizing agent and a radiation absorbing gas in a reaction chamber, where the pyrolysis is driven by heat absorbed from a laser beam. The zinc oxide particles preferably have an average diameter less than about 150 nm and more preferably an average diameter from about 5 nm to about 50 nm. In practicing the method, the laser beam preferably is produced by a CO.sub.2 laser and the molecular stream preferably is elongated in one dimension. Suitable zinc precursor include ZnCl.sub.2. [0009] In another aspect, the invention features a method for producing zinc sulfide particles comprising the step of pyrolyzing a molecular stream comprising a zinc precursor, a sulfur source and a radiation absorbing gas in a reaction chamber, where the pyrolysis is driven by heat absorbed from a laser beam. [0010] Other features and advantages of the invention are apparent from the following description of the preferred embodiments, and from the claims. BRIEF DESCRIPTION OF THE DRAWING [0011] FIG. 1 is a schematic, sectional view of an embodiment of a laser pyrolysis apparatus taken through the middle of the laser radiation path. The upper insert is a bottom view of the injection nozzle, and the lower insert is a top view of the collection nozzle. [0012] FIG. 2 is a schematic, perspective view of a reaction chamber of an alternative embodiment of the laser pyrolysis apparatus, where the materials of the chamber are depicted as transparent to reveal the interior of the apparatus. [0013] FIG. 3 is a sectional view of the reaction chamber of FIG. 2 taken along line 3-3. [0014] FIG. 4 is a schematic, sectional view of an oven for heating particles, in which the section is taken through the center of the quartz tube. [0015] FIG. 5 is a sectional view of an embodiment of display device incorporating a phosphor layer. [0016] FIG. 6 is a sectional view of an embodiment of a liquid crystal display incorporating a phosphor for illumination. [0017] FIG. 7 is a sectional view of an electroluminescent display. [0018] FIG. 8 is a sectional view of an embodiment of a flat panel display incorporating field emission display devices. DESCRIPTION OF THE PREFERRED EMBODIMENTS Continue reading... Full patent description for Phosphors Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Phosphors patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Phosphors or other areas of interest. ### Previous Patent Application: Funnel for use in a cathode ray tube Next Patent Application: Ultraviolet emitter display Industry Class: Electric lamp and discharge devices ### FreshPatents.com Support Thank you for viewing the Phosphors patent info. IP-related news and info Results in 4.90689 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , |
||
