Kodak, Agfa and Heidelberg have filed petitions with the U.S. Patent & Trademark Office (USPTO) in an effort to combat patent licensing demands made on their customers by CTP Innovations.

The three manufacturers are seeking to invalidate two US patents that relate to prepress and CTP workflows (6,738,155 and 6,611,349), which were originally filed by Banta Corporation in 1999.

CTP Innovations has acquired the patents seemingly with the aim of extracting licensing revenues from commercial printers - reportedly starting at $75,000 and rising rapidly the longer it takes for the claims to be settled.

The Printing Industries of America (PIA) has already failed in its attempt to get CTP Innovations' patents invalidated, although it has continued to act as a source of information for affected printers and to lobby the USPTO on behalf of the industry.

In a joint statement, the manufacturers said: "We fully support the proper use of the patent system to support legitimate intellectual property rights. However, we feel strongly that the infringement claims brought by CTP Innovations are without merit and the licensing demands are unsubstantiated. We feel it is important to take this action to support our customers from these frivolous claims.”

According to the PIA, more than 40 US printers have been sued for alleged patent infringement, while many hundreds more have been sent intimidating letters demanding payment of licensing fees.

The coalition added that it would continue to monitor CTP Innovations' litigation and licensing activities and that it would keep its respective customers updated with any further developments regarding the PTO review.

Agfa confirmed that the issue was restricted to the US as there are no corresponding patents elsewhere for so-called 'patent trolls' to exploit.