Browse Prior Art Database

ULTRA-VIOLET EPROM ERASURE INDICATOR

IP.com Disclosure Number: IPCOM000006330D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2001-Dec-25
Document File: 1 page(s) / 56K

Publishing Venue

Motorola

Related People

Christopher J. Wiggenhorn: AUTHOR

Abstract

Ultra-violet erasable PROMS have the capability of being erased by ultra-violet light. Unfortunately, there is no method of determining their erasure by inspection. Also, the variety of W intensities produced by ditferent erasers precludes any kind of universal erasure time for each EPROM. Even multiple EPROMs within the same eraser receive ditrerent amounts of light, occasionally resulting in some EPROMs being erased while others are not.

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MOTOROLA INC. Technical Developments Volume 14 December 1991

ULTRA-VIOLET EPROM ERASURE INDICATOR

by Christopher J. Wiggenhorn

   Ultra-violet erasable PROMS have the capability of being erased by ultra-violet light. Unfortunately, there is no method of determining their erasure by inspection. Also, the variety of W intensities produced by ditferent erasers precludes any kind of universal erasure time for each EPROM. Even multiple EPROMs within the same eraser receive ditrerent amounts of light, occasionally resulting in some EPROMs being erased while others are not.

  Many eyeglasses now include a photochromic mate- rial which darkens the lenses when exposed to sunlight, specifically ultra-violet light. This same material could indicate the amount of light to which an EPROM has been exposed. Different darkening rates would be needed

for diierent EPROMs. In addition, a slow rate of rever- sion to the lighter color would be more practical. The slower reversion rate would prevent the user from hav- ing to check the part soon r&r erasure.

  The photochromic material could either be incor- porated permanently into the EPROM's window (Exam- ple A) or used as a removable indicator (Example B). If removable, the material could take the form of a plastic ring to be temporarily placed on the window, or as a ring of film on a piece of removable tape. In any imple- mentation, the photochromic material would be in a shape of a ring covering the perimeter of the window, so as to...