FreshPatents.com Logo
stats FreshPatents Stats
2 views for this patent on FreshPatents.com
2013: 1 views
2012: 1 views
Updated: April 14 2014
newTOP 200 Companies filing patents this week


    Free Services  

  • MONITOR KEYWORDS
  • Enter keywords & we'll notify you when a new patent matches your request (weekly update).

  • ORGANIZER
  • Save & organize patents so you can view them later.

  • RSS rss
  • Create custom RSS feeds. Track keywords without receiving email.

  • ARCHIVE
  • View the last few months of your Keyword emails.

  • COMPANY DIRECTORY
  • Patents sorted by company.

AdPromo(14K)

Follow us on Twitter
twitter icon@FreshPatents

Sialon phosphor, process for producing the same, and illuminator and luminescent element employing the same

last patentdownload pdfdownload imgimage previewnext patent


20120270049 patent thumbnailZoom

Sialon phosphor, process for producing the same, and illuminator and luminescent element employing the same


Phosphor that can provide white LED that uses a blue LED or an ultraviolet LED as a light source and that has superior luminous efficiency. This phosphor includes, as a main component, α-type sialon represented by a general expression: (M1)x(M2)y(Si,Al)12(O,N)16 (where M1 is one or more types of elements selected from a group consisting of Li, Mg, Ca, Y, and lanthanide element (except for La and Ce) and M2 is one or more types of elements selected from a group consisting of Ce, Pr, Eu, Tb, Yb, and Er, and 0.3≦X+Y≦1.5 and 0<Y≦0.7 are established and the sialon phosphor consists of a powder having a specific surface area of 0.2 to 0.5 m2/g.


Browse recent Denki Kagaku Kogyo Kabushiki Kaisha patents - Tokyo, JP
Inventors: Hideyuki EMOTO, Masahiro IBUKIYAMA, Takashi KAWASAKI
USPTO Applicaton #: #20120270049 - Class: 428402 (USPTO) - 10/25/12 - Class 428 
Stock Material Or Miscellaneous Articles > Coated Or Structually Defined Flake, Particle, Cell, Strand, Strand Portion, Rod, Filament, Macroscopic Fiber Or Mass Thereof >Particulate Matter (e.g., Sphere, Flake, Etc.)

view organizer monitor keywords


The Patent Description & Claims data below is from USPTO Patent Application 20120270049, Sialon phosphor, process for producing the same, and illuminator and luminescent element employing the same.

last patentpdficondownload pdfimage previewnext patent

This application is a divisional of a pending application, U.S. Ser. No. 12/300,127 filed on Nov. 10, 2008, which is the National Stage Application of PCT International Application No. PCT/JP2007/059527, both of which are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present invention relates to sialon phosphor excited by ultraviolet light or blue light to emit visible light and the manufacture method thereof as well as an illuminator and a luminescent element using the same. In particular, the present invention relates to phosphor that can be used for a blue light-emitting diode (blue LED) or an ultraviolet light-emitting diode (ultraviolet LED) and the manufacture method thereof as well as an illuminator and a luminescent element using the same, in particular, a white light-emitting diode (white LED).

TECHNICAL BACKGROUND

Phosphor is well-known that uses silicate, phosphate, aluminate, and sulfide as host material and that uses transition metal or rare-earth metal for the luminescent center.

On the other hand, such white LED has attracted attention that is excited by an excitation source having high energy (e.g., ultraviolet light or blue light) to emit visible light and has been developed. However, when the above-described conventional phosphor is used, the exposure to the excitation source disadvantageously causes a decreased phosphor luminance.

As phosphor having a small decrease in the luminance, nitride or oxynitride phosphor has attracted attention recently as material that has a stable crystal structure and that can shift the excitation light and the light emission toward the long wavelength.

As nitride and oxynitride phosphor, α-type sialon (Si—Al—O—N) for which a specific rare-earth element is activated has been known as having a useful fluorescence characteristic and has been examined for the use to white LED or the like (see Patent Documents 1 to 5 and Non-Patent Documents 1 and 2).

The α-type sialon has a structure in which the Si—N bonds of α-type silicon nitride crystal is partially substituted with Al—N bonds and Al—O bonds and electroneutrality is maintained by a specific element (Ca, Li, Mg, and Y or lanthanide metal except for La and Ce) interstitially solid-soluted to a crystal lattice. A part of the interstitially solid-soluted element is a rare-earth element functioning as the luminescent center to cause the fluorescence characteristic.

The α-type sialon is obtained by burning mixed powders consisting of silicon nitride, aluminum nitride, optionally aluminum oxide, and the oxide of an interstitially solid-soluted element or the like in nitrogen at a high temperature. The proportion between silicon nitride and aluminum compound, the type of an interstitially solid-soluted element, and the ratio of an element functioning as the luminescent center for example can provide various fluorescence characteristics. In particular, α-type sialon, which is obtained by solid-soluting Ca functioning as an interstitially solid-soluted element and Eu functioning as the luminescent center, is efficiently excited in a wide wavelength range from a ultraviolet region to a blue region and emits light in a range from yellow to orange. Thus, the development of a combination of this α-type sialon with an LED emitting blue light (which is a complementary color to yellow to orange) has been expected for white LED.

Ca2(Si, Al)5N8, CaSiAlN3 or β-type sialon obtained by activating a rare-earth element also has been found to have the similar fluorescence characteristic (see Patent Documents 6 and 7 and Non-Patent Documents 2 and 3).

In addition, nitrides (e.g., aluminum nitride, silicon nitride magnesium, silicon nitride calcium, silicon nitride barium, gallium nitride, silicon nitride zinc) and oxynitride phosphor (hereinafter also referred to as nitride phosphor and oxynitride phosphor in this order) have been suggested.

In the case of the α-type sialon powders for example, the reduction-nitridation method has been known as a synthesis method of these phosphors. According to the reduction-nitridation method, mixed powders of aluminum oxide (Al2O3), silicon oxide (SiO2), oxide of metal or element that can be solid-soluted into the lattice or the like is subjected to a heating processing in nitrogen atmosphere under the existence of carbon (see Non-Patent Documents 4 to 6).

Although the methods reported in Non-Patent Documents 4 to 6 are characterized in that raw material powders are low-cost and can be synthesized at a relatively low temperature of about 1500 degrees C., a plurality of intermediates are caused in the synthesis and gas components such as SiO and CO are generated to difficultly provide the single-phase one, causing a difficulty in the strict control of the composition and the control of the particle size.

Sialon powders are also obtained by burning the mixture of silicon nitride, aluminum nitride, and the oxide of metal or an element or the like solid-soluted into the lattice at a high temperature to grind the resultant sintered compact. However, this has caused a problem of a decreased light emission intensity of phosphor due to a grinding operation.

As described above, in the conventional technique, nitride including a constituting element and a compound including an activating element are merely mixed and heated or the mixture of oxides of the constituting elements is merely subjected to reduction-nitridation by carbon or the like. This conventional technique cannot provide nitride phosphor or oxynitride phosphor having a sufficient characteristic.

In the case of sialon phosphor in particular, when a manufacture method is used in which oxides including the constituting elements of solid-soluted elements (e.g., calcium or yttrium) or the activating element (e.g., cerium, europium) are used as raw material, a burning process causes a liquid-phase sintering to cause a stronger binding among particles. This has caused a case where a grind processing under severe conditions may be required in order to obtain powders having a target particle size. In this case, the grind processing under severe conditions cause an increase in the contamination and introduce defects into the surfaces of the respective particles, thereby disadvantageously causing a deteriorated light emission characteristic.

In order to solve this problem, the present inventors have suggested a manufacture method rarely requiring a grind processing by using raw material not including oxygen (e.g., raw material such as calcium fluoride or calcium cyanamide) and by devising a method for mixing raw materials for a burning process for example. Thus, the present inventors could improve the light emission intensity (see Patent Documents 8 and 9).

In order to realize white, a combination of a plurality of colors different from a monochromatic light is required. A general white LED is composed of a combination of ultraviolet LED or blue LED and phosphor that uses the light from the LED as an excitation source and that emits visible light (see Patent Documents 10 and 11 for example). Thus, in order to improve the white LED efficiency, it is required to improve the luminous efficiency of the ultraviolet LED or the blue LED itself and to improve the efficiency of phosphor in the LED. It is also required to improve an efficiency at which emitted light is taken out to the outside. In order to increase use of white LED including a general lighting use, all of these efficiencies must be improved. Patent Document 1: Japanese Patent No. 3668770 Patent Document 2: Japanese Patent No. 2003-336059 A Patent Document 3: Japanese Patent No. 2003-124527 A Patent Document 4: Japanese Patent No. 2003-206481 A Patent Document 5: Japanese Patent No. 2004-186278 A Patent Document 6: Japanese Patent No. 2004-244560 A

Download full PDF for full patent description/claims.

Advertise on FreshPatents.com - Rates & Info


You can also Monitor Keywords and Search for tracking patents relating to this Sialon phosphor, process for producing the same, and illuminator and luminescent element employing the same patent application.
###
monitor keywords



Keyword Monitor How KEYWORD MONITOR works... a FREE service from FreshPatents
1. 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 Sialon phosphor, process for producing the same, and illuminator and luminescent element employing the same or other areas of interest.
###


Previous Patent Application:
Nano-sized diene-based polymer latex particles
Next Patent Application:
Functionally coated non-oxidized particles and methods for making the same
Industry Class:
Stock material or miscellaneous articles
Thank you for viewing the Sialon phosphor, process for producing the same, and illuminator and luminescent element employing the same patent info.
- - - Apple patents, Boeing patents, Google patents, IBM patents, Jabil patents, Coca Cola patents, Motorola patents

Results in 0.72346 seconds


Other interesting Freshpatents.com categories:
Amazon , Microsoft , IBM , Boeing Facebook -g2-0.2003
     SHARE
  
           

FreshNews promo


stats Patent Info
Application #
US 20120270049 A1
Publish Date
10/25/2012
Document #
13464855
File Date
05/04/2012
USPTO Class
428402
Other USPTO Classes
International Class
/
Drawings
0




Follow us on Twitter
twitter icon@FreshPatents