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End-of-forms Detection Device

IP.com Disclosure Number: IPCOM000060679D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Fox, S: AUTHOR [+3]

Abstract

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.

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End-of-forms Detection Device

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.

When the paper is inserted from the front of the guide 1, it will contact the projection 6. When the paper is inserted from the rear of the guide 1, it will contact the projection 5. The contacting of either projection 5 or 6 will cause the arm 4 of the flag 3 to rotate from its home position and allow the light from the source, which is not shown, to impinge upon the switch 2 thereby enabling the machine to operate. When the edge of the paper is fed past the flag 3, the flag 3 returns to the "home" position, as shown in Figure 1, such that the arm 4 cuts off the light from the switch 2 thereby, through supporting electronics, turning off the machine and preventing printing past the edge of the paper.

The flag 3, as shown in Figure 2, is made of black polyca...