Aperture card
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An aperture card is a type of punched card with a cut-out window into which a chip of microfilm is mounted. Such a card is used for archiving or for making multiple inexpensive copies of a document for ease of distribution. The card is typically punched with machine-readable metadata associated with the microfilm image, and printed across the top of the card for visual identification. The microfilm chip is most commonly 35mm in height, and contains an optically reduced image, usually of some type of reference document, such as an engineering drawing, that is the focus of the archiving process.
Aperture cards are used for engineering drawings from all engineering disciplines. Information about the drawing, for example the drawing number, could be both punched and printed on the remainder of the card. A set of cards could be rapidly sorted by drawing number or other punched data using a card sorter. Machines are now available that scan aperture cards and produce a digital version. The U.S. Department of Defense once made extensive use of aperture cards, and some are still in use, but most data is now digital.[1]
Aperture cards have, for archival purposes, some advantages over digital systems, for example: 100 year lifetime, human readable, and no expense or risk in converting to the next digital format.[1]
[edit] References
- ^ LoTurco, Ed (January, 2004). "The Engineering Aperture Card: Still Active, Still Vital". . EDM Consultants
[edit] External links
- 1959 Defense Technical Information Center report on the technology and its use for submitting engineering plans to the military.
- Detailed description of a particular format of Aperture cards from WIPO.
