Improving Performance In Computer To Plate Printing Using Semiconductor Laser Arrays

By Professor John H. Marsh, Ph.D., Founder and Chief Technical Officer, and Stephen P. Najda, Ph.D., Technical Expert, Intense Ltd.

Over the last 25 years, electronic typesetting and desktop publishing (DTP) have revolutionized the printing industry. Almost anyone with a computer and the right software can create and print professional materials. However to achieve the highest print quality, it is still necessary to use a commercial or industrial printer with advanced technology for delivering state of the art print quality standards.

In DTP, text is input using a word processor running on a desktop or laptop computer and then transferred electronically to a page layout package. The page layout software enables an editor to determine the precise appearance of the printed page. For most commercial and industrial printing, the page is then imaged onto printing plates that are mounted on a printing press. A single printing plate is used for monochrome and several plates for color (a minimum of 4 plates but usually 6 or more). These plates are imaged using computer to plate (CtP) systems, so CtP has become a key technology in almost every printing house. CtP printing is the de facto standard for the highest quality printing that can be achieved.

As recently as the 1970s, the preparation of printing plates was a craft industry, with compositors using hot-metal typesetters to cast lines of text. These lines of text were then set in a frame by hand to give the final page layout. This process remained essentially unchanged for almost a century. Automation began in the 1970s with photo-typesetting, a technology that used entirely photographic techniques to create an image on photographic paper. The images were then pasted up and transferred photographically to a printing plate. However, the present day combination of page layout software and CtP systems eliminates all of the hand composition stages.