March 06, 2004
Proof-of-Concept: The Low-Cost Library Project
David Lobosco, Sal Scaturro and Saul Griffith worked on the initial proof-of-concept model of the microfilm projection system, as part of the DtM02 Seminar and Design Studio course at the MIT Media Lab. The initial design used a 1-watt red LED to back-project an image of microfilm onto a wax paper screen. The group stored a number of data files and internet references in their ThinkCycle on-line archive.
"The goal of this project is to develop a low-cost system for delivering the information found in printed or web-based material to those in the developing world. Our idea is to store the information on microflim rolls that would be housed in ordinary cassette tapes. The microfilm would contain 4mm x 3mm images that could then be magnified using simple optics and either viewed by a single user, or projected. An individual could use a binocular device held up to the eyes to view the information while a separate tool could be designed to display the image on a screen for multi-person viewing. The microfilm reader would either be battery powered, using a Light Emitting Diode (LED) as the light source, or utilize the light from the sun as its source of illumination. A single microfilm cassette will hold about 90,000 pages of text or graphics." -- from their initial project proposal.
Posted by Timothy Prestero at March 6, 2004 01:05 PMThis is an interesting idea, and might be taken farther in interesting ways.
When you say "cassette", I think of something other than 'microfilm cassette'. Why not use a standard "compact cassette" shell (and drive components) as the basis for one version of this project:
1) A suitable transparent or translucent material could easily be found or specified which could take permanent microform images, and then be spliced together with magnetic tape in a single shell. Inserting a light-source/lens arrangement through one of the existing holes in the cassette (e.g. by incorporating it into one of the locating pins in an otherwise-conventional tape transport) and providing appropriate optics opposite this, ought to provide comparable performance to the existing reader design. Existing sensors (e.g. the 'fast-reverse' sensors in some Aiwa tape decks) could detect transitions between printed and audio materials, and cue the transport appropriately; other sensors could use data or tone coding in the magnetic tape to position offsets accordingly if desired. This would allow spoken-word information to accompany pictures or diagrams for users without reading skills in a particular language or group of languages.
2) A similar concept, with sequential frames of microform in parallel with a magnetic strip or strips, would allow movie frames or a full set of still images to coexist with magnetic-recorded material. (I would not think it difficult to have a magnetic-and-microform track pair for either 'side' of a cassette, without compromising the ability of the cassette to 'play back' at least one channel on a standard audio player).
3) With some care, either the front or back side of magnetic tape could be overprinted with (microform) images with different reflective characteristics. This would be markedly effective if either the image or the background were highly reflective, which would reduce the lighting requirements. Reading the image off the outside of the tape is not difficult (requiring one or more off-axis light sources and an appropriate 'projection' lens system). Reading off the back side of the tape, perhaps a preferable location for magnetic-tape engineering reasons, might be done with a pair of fiber-optic-bundle light sources with appropriate molded or formed lenses, flanking a prismatic or mirror system to take the reflected image out of the area of the shell.
4) For applications needing greater illumination or more physical space (e.g. for removing IR from the projected light) it would not be difficult to provide an arrangement of picking arms, like those used in helical-scan transports, which would remove the tape from the normal path in the shell and wrap it around whatever optical and magnetic heads are best. I believe several designs of DCC player, which used drum heads and helical scan on 1/8" tape, have already done DFM on this arrangement. Note that the ability to run the cassette in standard players is not necessarily compromised by this operating mode; I believe the two capstan holes in the cassette can be 'opened' to the perimeter of the shell, on one or both sides, if this is desirable for the extraction machinery, without compromising the ability to play cassettes in ordinary players.
I think that many of the fixed costs of designing and providing usable players might be reduced with these types of approach, particularly if there are ways of incorporating the projection equipment into existing designs of cassette machine.
Posted by: R.M.Ellsworth at March 6, 2004 06:31 PM
