Browse Prior Art Database

Field Limiter for Optical Wand

IP.com Disclosure Number: IPCOM000038724D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Feldhacker, ME: AUTHOR [+2]

Abstract

The output copy bin of a xerographic copier includes a vertically movable table upon which output copy sheets are stacked. The vertical height of the table is controlled by an optical wand and a servo motor. The optical wand comprises a light source located on one side of the table and a photocell located on the other side of the table. The photocell's field of view of the light source is restricted and controlled by a bundle of hollow pipes, thereby to reduce the effect of room ambient light on the photocell. Fig. 1 is a top view of copy-stacking table 10. Output copy paper moves in the direction of arrow 11 as it exits the copier (not shown) and enters the table area. An infrared light-emitting diode (LED) 12 is mounted to project a generally horizontal beam of light across the table, toward phototransistor 13.

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Field Limiter for Optical Wand

The output copy bin of a xerographic copier includes a vertically movable table upon which output copy sheets are stacked. The vertical height of the table is controlled by an optical wand and a servo motor. The optical wand comprises a light source located on one side of the table and a photocell located on the other side of the table. The photocell's field of view of the light source is restricted and controlled by a bundle of hollow pipes, thereby to reduce the effect of room ambient light on the photocell. Fig. 1 is a top view of copy-stacking table 10. Output copy paper moves in the direction of arrow 11 as it exits the copier (not shown) and enters the table area. An infrared light-emitting diode (LED) 12 is mounted to project a generally horizontal beam of light across the table, toward phototransistor 13. Lenses, comprising an immersion element, an aspheric element, and finally a plano-convex element (not shown) are located in front of both the LED and the phototransistor to focus the light and collect it in a nearly parallel manner. Because the LED and the phototransistor are of a finite size, their operating beam fields are considerably larger than the diameter of the lens. At a distance of about twenty-four inches, the LED's beam pattern is somewhat greater than six inches across, or a seven-degree half- angle, while the phototransistor has a viewing half-angle somewhat greater than seventy-five degrees, due to the larger...