Browse Prior Art Database

Film Supply Indicator

IP.com Disclosure Number: IPCOM000049544D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Yarrington, JC: AUTHOR

Abstract

The amount of film remaining on a supply spool 1 is computed electronically by comparing the ratio of steps taken by stepper motor 2 to the ratio of steps of a capstan 3 taken by a drive stepper motor 4. When the supply of film on spool 1 is nearly exhausted, an indicator 5 will be activated in response to this detection.

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Film Supply Indicator

The amount of film remaining on a supply spool 1 is computed electronically by comparing the ratio of steps taken by stepper motor 2 to the ratio of steps of a capstan 3 taken by a drive stepper motor 4. When the supply of film on spool 1 is nearly exhausted, an indicator 5 will be activated in response to this detection.

A film supply for a microfilm camera is shown. The film 6 is tracked from supply spool 1 past a number of idler rollers 7 and capstan 3 to a takeup spool 8 that is rotated by a stepper motor 9.

The film is formed into a pair of loops 10 and 11 by respective vacuum columns 12 and 13, positioned to either side of an exposure aperture 14. Pressure sensitive controls 15 and 16 respond to the position of loops 10 and 11 to maintain the loops essentially constant in size by controlling stepper motors 2 and 9. Capstan 3 feeds uniform increments of the film 6 past exposure station 14.

Such feeding tends to enlarge loop 11 and diminish loop 10.

Following each capstan advance, control 15 determines whether loop 10 is above port 17 and, if so, causes a step operation of stepper motor 2 to advance an increment of film into vacuum column 12. A similar operation occurs to move film loop 11 with respect to port 18 by stepping the takeup stepper motor 9. Each time motor 2 completes 32 steps, the number of steps taken by capstan motor 4 is read as a measure of the diameter of film on supply spool 1. When this measurement reaches a pre-set t...