End-of-forms Detection Device
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-09
This article describes a low cost end-of-forms detection switch that can be reliably tripped by paper approaching it from either of two opposite directions. Existing devices for forms detection make use extensively of microswitch mechanical level arms switches requiring intricate assembly. Another alternative is the use of costly reflective sensors which present reliability problems due to paper dust and the variability in reflectance of different papers and materials. The deficiencies of existing devices are avoided in the mechanism of Figure 1 which shows a paper guide 1, an infrared LED phototransistor switch 2 and an end-of-forms flag 3 which rotates in a slot in the guide 1.