White LED patent status
Tao Yuxiang Li Hongbo compiled
The five major companies Nichia, Osram, Toyoda Gosei, Cree and Lumileds almost control the entire white LED industry. The patents are dense, and it can be said that the minefields are heavy, making other merchants who want to enter this field worry and discouraged. However, many companies Still strive to gain a foothold in this field. The extensive and rapid application of white LEDs and the strong investment of major companies in this field, patent infringement, cross-licensing and other legal matters continue to occur.
Diagram of licensing and patent disputes (primary intellectual property relations) in the field of white LEDs since September 2005
After long-term patent disputes, the five major companies have chosen “mutual (cross) authorization†to quell conflicts and disputes (as shown above). As a result, the LED industry is quiet. But the days in this field or other businesses that want to enter this field seem to be even worse.
The scope of the license covers all aspects of fixed light-emitting transistor technology, but the most important and interesting technology in this field is the technology that uses phosphorescent powder to convert blue and ultraviolet light into white light. In this way, major companies no longer have to argue with each other for the effectiveness of their own various patents, but instead focus on whether someone infringes their patents and licenses their technology to other lesser ones. the company.
Worse, these agreements don't help much to clarify the IP location, determine which patents are valid, and which have priority. Reading the patent literature reveals a series of patent documents that are duplicates or even conflicting with US patents. At present, the law on infringement has been gradually promulgated. Although some of the appeals are infringing, others have rejected such appeals. So far, the real decree on the validity of patents is still very limited.
In many practical cases, the subject of patent protection is not very clear. At the time, there was not even a truly effective patent to protect the principle of illumination of white LEDs. The US patent that protected screens to convert colors in 1970 was no exception. In 1991, Nichia was rejected for patent applications in the United States for the use of phosphors to convert blue LEDs into white light. As for the reasons for the refusal, I don't know if it is because the previous US Patent Office has accepted patents of the same nature.
Comparing the many patents, it is easy to see that the protection focus is on the use of phosphors. Before the cross-contract was signed, Nichia appealed to Osram to use a Japanese patent for infringement. The reason for rejection was that Osram did not use garnet phosphorescence. body). As a result, subsequent patents began to expand the scope of protection, so that the content of protection is more and more extensive but also less clear.
White LED US Patent Status
If Nichia first commercialized white LEDs in 1996, the history of white LEDs can be quite complicated. In the United States, the patent status is roughly as follows:
â—† Bell Labs uses single or multiple phosphors for the illumination of fluorescent screens, which is protected by the US patent (3,691,482) and also establishes the wavelength conversion principle of light. The patent was accepted on January 17, 1970.
â—†Nichia applied for a Japanese patent on November 25, 1991, “The use of phosphors in resins and for moldingâ€, which was published on June 18, 1993, but was applied in 1998. On March 23, it was rejected and on December 2, 1999, Nichia withdrew the application.
â—† Cree owns a patent of 6,600,175 (which was originally granted to AMTI) with an acceptance date of March 26, 1996 and an authorization date of July 29, 2003. The patent claims to protect a "device that produces white light from a single LED by down-converting phosphors" and attempts to protect all related technologies and processes. However, the patent mentions only the excitation of the phosphor by a light source other than white light. It does not seem to cover the excitation of the yellow phosphor by the usual blue LED. Nichia mentioned in the patent that the blue LED is excited by the yellow phosphor, but there is no This is discussed and there is no discussion of garnet-based phosphor technology.
â—† Osram's patent 6,245,259 was accepted on US August 29, 2000, and the date of authorization was June 12, 2001. However, prior to June 26, 1997, he was protected by international patents. Since then, there has been a problem of patent overlap. The original patents describe blue, green, and ultraviolet LEDs with phosphors doped with antimony, bismuth or thiogarnet. This has not been mentioned in the previous Nichia white LEDs and Nichia Japanese patent applications. The focus of this technology protection seems to be on the phosphor size specification (the size is below 5 microns).
â—† HP (Agilent) patent 5,847,507 is accepted on July 14, 1997, and the authorization date is December 8, 1998. The description of this patent relates to existing Nichia products and the focus of protection is on the principle of luminescence of phosphors, which covers a wide range of phosphors of various types.
The first Nichia patent 5,998,925 in white LED applications was authorized in the United States on December 7, 1999, and its acceptance date was July 29, 1997, which was incorporated into later Nichia patents 6,069,440 and 6,614,179. As expected, this patent relates to garnet-based GaN LED phosphors - describing Nichia commercial white LEDs. Although the Nichia US patent disclosure touched on their early patents, it is a strong irony for the statement that “the first commercial white LED supplier has the latest priority dateâ€.
â—†Toyoda Gosei has patent 6,809,347 to protect alkaline earth orthosilicate phosphors doped with barium and blue or UV LEDs. This patent has a priority date of December 28, 2000, and is authorized on October 26, 2004. It seems to focus on the protection of a particular phosphor design in a clear-cut manner. It does not take the same measures as other patents. The word is vague and its protection is clear and clear.
Phosphor
The biggest difference with many patents is that the phosphor can be freely selected. The main phosphors have the following:
â—† YAG with yttrium element, this compound is excited under the illumination of 460 nanometer meters, and can emit light waves of 550 nm in a wide range;
â—† Osram company authorized a few manufacturers of yttrium aluminum garnet (TAG);
a phosphor composed of a sulfide, such as a thiophthalate doped with antimony, which is excited under the illumination of 460 nanometers of light and capable of emitting green light having a wavelength of 550 nanometers; or a sulfide of cerium doped with cerium, which produces red light under such conditions;
â—† Silicate-containing phosphors, which have been patented by Toyoda Gosei and Tridonic and Intematix;
â—†Organic phosphor or dye (powder), whether the fluorescent color rendering includes the first two items, there is no clear information for the time being;
â—† Nanoparticle phosphors are the most widely used methods in other patents, but the method (process) is not mentioned in the above several articles.
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