As a magazine for one of the fastest growing sectors of the printing industry, FlexoTech had to keep its readers informed of the latest technologies.
FlexoTech: August/September 1996
Web viewing in real time
Quality control on reel-to-reel printing presses is managed through web video inspection monitors. Good systems provide the operator with cost effective equipment, which can reduce waste, increase productivity and improve quality.
Video inspection allows the press operator to see the printed image produced by the web presses clearly and in real time. Some manufacturers of such systems would argue that the image produced is far better than can be seen by the naked eye.
A video camera scans the web one section at a time, and through the system’s electronics an image is passed back to the monitor. These images can be magnified to show detail of register or colour. Indeed, the image can be stored in memory for comparisons and colour matching while the press is running. The most sophisticated systems can identify defects and initiate corrective action on the press.
The camera, mounted close to the web, fires high intensity, short duration Xenon strobe lights at intervals that must be synchronised precisely with the press. The strobes illuminate the web and act as a super fast shutter, in order for the electronic camera to stop the action and capture a still video picture.
The system’s electronics and software take the image from the camera in a matter of milliseconds, digitise the data and save it in the memory bank. The information is then sent to the operator’s monitor for inspection of the image.
