To avoid scraping from arched printing mediums or foreign objects, many printer brands have deployed anti-scraping devices on their products. The most commonly seen device on the current market is a snap-action mechanical structure.
Snap-action devices use a micro switch with a detection metal strip installed on the side of the printhead assembly. When the metal strip touches an arched printing film or other foreign objects, it triggers the microswitch to stop the printer. Due to its simple configuration and cost-effective materials, snap-action devices are generally inexpensive and widely used on printing machines.
However, despite its cost-effectiveness, its functionality falls short. Since printing mediums like paper or film can be quite lightweight, the detection strip often fails to effectively sense their curvature and does not stop printing in a timely manner. As a result, it only reduces the risk of printhead scraping by 20%. Additionally, because the device relies on contact-based sensing, it is prone to contamination from printed inks, leading to false triggers and requiring frequent maintenance.