This is a list of software patents, which contains notable patents and patent applications involving computer programs (also known as a software patent). Software patents cover a wide range of topics and there is therefore important debate about whether such subject-matter should be excluded from patent protection. However, there is no official way of identifying software patents and different researchers have devised their own ways of doing so. This article lists patents relating to software which have been the subject of litigation or have achieved notoriety in other ways. Notable patent applications are also listed and comparisons made between corresponding patents and patent applications in different countries. The patents and patent applications are categorised according to the subject matter of the patent or the particular field in which the patent had an effect that brought it into the public view.
Business methods
Data compression
Data compression in general US 5016009 – (Main article: Stac Electronics) US 4701745 – also granted as GB 2172127 - now expired Stac Electronics sued Microsoft for patent infringement when Microsoft introduced the DoubleSpace data compression scheme into MS-DOS. Stac was awarded $120 million by a jury in 1994 and Microsoft was ordered to recall versions of MS-DOS with the infringing technology.
Audio compression US 5579430 – (Main article: MP3) One of several patents covering the MP3 format owned by the Fraunhofer Society which led to the development of the Ogg Vorbis format as an alternative to MP3. US 5627938 – (Main article: Alcatel-Lucent v. Microsoft) US 5341457 Two patents owned by Alcatel-Lucent relating to MP3 technology under which they sued Microsoft for $1.5 billion. Microsoft thought they had already licensed the technology from Fraunhofer, and this case illustrates one of the basic principles of patents that a license does not necessarily permit the licensee to work the technology, but merely prevents the licensee from being sued by the licensor.
Image compression US 4558302 (Main article: GIF) EP 0129439 Unisys's patent on LZW compression, a fundamental part of the widely used GIF graphics format. US 4698672 and its EP equivalent EP 0266049 (Main article: Forgent Networks) Forgent Networks claimed this patent, granted in 1987, covered the JPEG image compression format. The broadest claims of the US patent were found to be invalid in 2005 following re-examination by the US Patent and Trademark Office. US 5710835 EP 0864135
This patent, owned by Lizardtech, Inc., was the subject of infringement proceedings against companies including Earth Resource Mapping, Inc. However, Lizardtech lost the trial on the grounds that an important part of their invention was the step of "maintaining updated sums of discrete wavelet transform coefficients from the discrete tile image to form a seamless discrete wavelet transform of the image". Claim 21 of the patent lacked this feature and was therefore obvious. The remaining claims contained this feature, but were not infringed by ERM. Internet buzz suggested the patent covered the JPEG 2000 image compression format but the additional feature of the valid claims appears not to be a JPEG 2000 requirement.
Video compression
Data encryption
Gaming systems EP 0625760 (Main article: Menashe v. William Hill) A patent for a gaming system that has particular importance regarding Internet usage. A server running the game was located outside the UK but could be used within the UK. The Court of Appeal of England and Wales judged that the patent was being infringed by virtue of the sale of CDs in the UK containing software intended to put the invention into effect in the UK.
Image processing US 6137498 also granted as EP 0852363 - (Main article: Photographic mosaic) Robert Silver's patent on his photographic mosaicing technique. The UK part of the European patent is currently undergoing revocation proceedings, the results of which may be important in comparing the practice of the UK Patent Office with that of the European Patent Office. US 6384822 (Main article: Shadow volume) A patent covering the technique commonly known as Carmack's Reverse
Internet tools
Fair division US 5983205 - (Main article: Adjusted winner procedure) An algorithm to divide n divisible goods between two parties as fairly as possible.
Search engines US 6269361 (Main article: Yahoo! Search Marketing) A patent relating to pay-per-click Internet search engine advertising. Originally filed by Goto.com, Inc. (renamed Overture Services, Inc.), Google and FindWhat were both sued for infringement prior to Overture's acquisition by Yahoo!
Telecommunications US 7116963 Washington Research Foundation asserted this patent in December 2006 against Matsushita (owners of the Panasonic brand), Nokia and Samsung. Granted in October 2006 (originating from a 1996 filing) it relates to dynamically varying the passband bandwidth of a tuner. If the claims had been upheld, CSR plc (previously known as Cambridge Silicon Radio), who supply the defendants with Bluetooth chips, could have lost market share to Broadcom who already had a license under the patent. US 4744028 One of three patents granted in respect of Karmarkar's algorithm, which relates to linear programming problems. Claim 1 of this patent suggests the algorithm should be applied to the allocation of telecommunication transmission facilities among subscribers.
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