Presstek Inc., a maker of laser-based computer-to-press print heads, has notified Creo Products Inc. of Burnaby, British Columbia, Canada, that it is infringing Presstek's patents covering on-press imaging of printing plates. Presstek has not filed suit, but the dispute has been brewing since Creo asked the US Patent and Trademark Office to re-examine one of the patents. A second Presstek patent was re-examined after an anonymous request. The patent infringement dispute could become a concern for companies that supply the laser diodes used in the imaging equipment. Presstek uses laser diodes supplied by Opto Power Corp. in Tucson, Ariz., and other firms, according to Efrem Lieber, vice president of sales and marketing. The patent office completed its re-examination in June. Presstek interpreted the agency's review as strengthening and narrowing its claims. Chief Financial Officer Neil Rossen said the company would be able to take more vigorous action when it receives the patent office's judgment in writing. He declined to answer whether Creo had responded to the notice, except to say that "we are not satisfied." In a prepared statement, Creo spokesman Nick Brampton said the company is confident that none of its products infringe the intellectual property rights of others. After being put on notice, the company filed an action in US District Court in Delaware seeking a declaration that its products "do not and will not infringe." The direct imaging system uses arrays of 16 to 30 laser diodes per module to produce a series of spots on the imaging plate surface. Each laser beam passes through a fiber optic coupler to a lens assembly that focuses it to a fine spot (18 to 35 µm) that ablates the plate to make an ink-holding dot. Depending on the speed and timing of the press, the lasers operate at 830 to 915 nm. Karat Digital Press L.P. in Herzliyya, Israel, and other companies that make the print heads already license the technology from Presstek, Lieber said, and he indicated that the firm would like to reach a licensing agreement with Creo. "There is no need for litigation. There is need for negotiation." Neither company would comment on whether licensing negotiations had already started. Brampton said Creo indemnifies its customers from all infringement claims. Lieber estimated that licensing might add 10 to 30 percent to the cost of the device, depending on its complexity and level of resolution. Demand for the printing systems has been growing, with both firms reporting strong sales.