Book on a pocket card

A plastic card or credit card size has a strip of optical recording material thereon containing microtext. The microtext is either electronically or optically reduced from 5 to 200 times and laid out in miniature pages, arranged in an array on the strip. The strip has a metallic or metal particle layer, giving it a shiny gold or silver coloration, against which the microtext appears dark, or vice-versa.

TECHNICAL FIELD 
The invention relates to microtext publishing and in particular to a medium 
for such publishing. 
BACKGROUND ART 
One of the best known publications employing microtext is "The Compact 
Edition of the Oxford English Dictionary", Oxford University Press, 1971. 
In this work, a large number of volumes of the Oxford English Dictionary 
have been reduced to two volumes. Ordinary size print has been reduced to 
the point of being barely readable to the unaided eye. Without 
microprinting, only libraries and institutions usually had the Oxford 
English Dictionary. Using microtext, many readers are able to possess this 
widely recognized work. 
Even though microtext on paper is very useful, the works require more 
handling than usual for two reasons. First, because of the very high 
information density on each page, the amount of access for each is 
increased. Secondly, because of the need for magnification, a page will be 
handled for proper positioning with regard to a magnification apparatus. 
Other well-known microtext media are microfilm and microfiche. Such media 
are used to store records, books and for other uses. An advantage of 
microfilm and microfiche is that they are more durable than paper and 
require less space. To use microfilm or microfiche, a reading apparatus is 
used which projects light through the film or microfiche and then onto a 
screen where an image is created and sometimes reproduced. A disadvantage 
of microfilm and microfiche is that they cannot be carried in the pocket, 
wallet or purse. Microfilm is too bulky and microfiche is 4 inches by 6 
inches in size making it too large to be carried in a wallet. Microfilm 
and microfiche can be scratched in handling since they do not have any 
protective layer over the recorded surface. Further, microfilm and 
microfiche are not attractive, particularly for carrying sacred 
scriptures. Also, microfilm and microfiche require transmissive type 
readers. 
An objective of this invention was to devise a durable microtext medium 
that is credit card size, has a protective plastic layer over the recorded 
medium to prevent scratching, and is read in reflection to permit printing 
on the back of the card. 
DISCLOSURE OF THE INVENTION 
The above object has been achieved using an opaque card with a planar 
surface over which a light reflective medium is disposed. This medium has 
reflectivity greater than 20% and is gold or silver in color. Characters 
are created on the medium by photolithography or by electroforming. No ink 
is used. Characters on the medium are reduced in size from the usual 
height by 5 to 200 times. The characters appear to be dark with regard to 
the surrounding reflective field because of differences with respect to 
the coloration of the field or because of scattering of light. Of course, 
the field could have a reverse relationship with respect to the 
characters. Either the characters or the field material, or both, are 
metallic or formed with metal particles. This adds an archival character 
to the medium. To protect the thin strip, the entire card is covered with 
a transparent cover. 
An advantage of the card is that text characters of an entire book may be 
photographically reduced and microscopically engraved or etched onto a 
strip of the type described above which is then adhered to a card. The 
resulting card provides a very convenient means for providing access to 
microtext forming a book.

BEST MODE FOR CARRYING OUT THE INVENTION 
With reference to FIG. 1, a card 11 is shown which is preferably of credit 
card size. The card includes a planar plastic base 13 and a strip 15 of 
recording material disposed thereon. The plastic base 13 is opaque and 
self-supporting. Strip 15 has a metallic coloration, either silver or gold 
in color. Small rectangles 17 are photolithographically etched or 
micromachined into the strip. These rectangles are the "pages" of the book 
containing dark microtext. It is possible to reverse the coloration and 
provide bright rectangles in a dark field. An electron beam or a finely 
focused laser beam will be used to create a photomask which in turn will 
be used to create strip 15 by photolithography. Micromachining techniques 
could also be used. 
A micromachining or photolithographic process used to form alpha-numeric 
characters maintains a size reduction between 5 and 200 times with regard 
to ten point type. A size reduction of 100 times will allow up to 1500 
normal size pages to be placed on a strip which is approximately 35 mm 
wide and 85 mm long, with ample borders about the periphery of the strip. 
Reflectivity of the shiny region should exceed 20% and preferably about 
50%. 
In the side and edge views of FIGS. 2 and 4, the card is shown to be flat 
on both sides. Upper surface 21 has a thin transparent plastic cover over 
the recording strip which, because of its thinness, is not seen in the 
FIGS. In FIG. 3, the backside 19 is shown to be blank, but could have a 
strip similar to the front side or could have normal-sized printing 
affixed thereto, either directly on the plastic base material or on 
another material adhered to the base. 
In FIG. 5, lines of microtext 23 are shown to be arranged in pages, with 
streets 25 separating the pages. While the rectangles are placed in a 
side-by-side array, other patterns are also possible, such as a circular 
pattern or a pattern forming a decorative array when viewed with the 
unaided eye. The microtext may be formed by optical reduction in a 
photolithography process or by direct beam writing of microtext, both 
methods being discussed below. 
FIG. 6 is a perspective view of a folded flat card jacket with a pair of 
cards inside. In FIG. 7, the jacket 31 is shown partially open, having a 
pair of pockets 33 and 35 wherein the card may be placed. The pockets are 
opaque on their outside surface, but transparent on the inside. 
In FIG. 8, the jacket 31 is shown to be in a fully opened position with a 
pair of cards 37 and 39 inside of the flaps 33 and 35. When the jacket is 
closed, both cards are protected. 
With reference to FIG. 9, a detailed construction is shown. Card base 13 is 
shown underlying strips of laminate portions 41, 43 and 45 and then 
covered by a transparent plastic cover member 47. The laminate members 
form the storage material and possess the characteristic reflective silver 
or gold coloration. The storage material need not be a laminate, but may 
be a single metal-on-substrate medium, such as one of the well-known 
direct-read-after-write laser recording materials which may be written 
upon by micromachining. See, for example, U.S. Pat. No. 4,230,939 to de 
Bont. Thus, there are many variations of FIG. 9. Layers 41, 43 and 45 can 
be one composite material. Any or all layers 41, 43 and 45 could be the 
same size as layer 47 and additional layers could be added for mechanical 
construction purposes. 
The preferred embodiment involves a composite material with a lower 
transparent layer 41 made of Mylar, a tradename for a polyester film. The 
preferred material over layer 41 is a gelatin polymer layer 43 with an 
upper crust layer 45 formed thereon consisting of primarily spherical 
metal particles in a colloidal matrix. The details of the construction of 
the recording strip may be found in U.S. Pat. No. 4,304,848 entitled 
"Method for Photographic Replication of Information on an Optical Data 
Storage Medium". In that patent, a technique is described for converting a 
photosensitive emulsion into a gelatin and a colloid containing primarily 
spherical silver particles which form a reflective layer. This reflective 
layer is represented by the uppermost portion 45 in FIG. 9. The portion 43 
is intimately joined with the region 45 and is not a physically separate 
layer as shown in the drawing. The substrate portion 41 is also intimately 
joined to layers 43, but 41 was a separate layer before layer 43 was 
joined to it. 
An alternative storage material is formed by vacuum deposition of a metal 
such as aluminum onto a plastic sheet. In this situation, this metallic 
underlayer would be portion 41 which would be covered with a photoresist 
during the manufacturing process. It would be exposed through a photomask 
and the photoresist would be developed. The aluminum underlayer would be 
etched and then the photoresist would be stripped off. The text would thus 
be etched into the aluminum underlayer. Black ink would cover the entire 
back creating black letters in a reflective aluminum field. 
In one embodiment, the thickness of the lower-most portion 41, where the 
portion is a plastic substrate is approximately 100 microns. The thickness 
of the intermediate portion 43 where such intermediate portion is a 
gelatin layer is approximately 4 microns. The thickness of the uppermost 
colloidal and metal particle layer 45 is approximately 0.5 to 1.5 microns. 
The thickness of the transparent protective cover 47 ranges between 125 
and 400 microns. The preferred material of the transparent plastic cover 
47 is polycarbonate with a hardener coating. The thickness of the 
substrate 13 is about 0.5 millimeter. 
Equipment for micromachining or etching by means of photolithography the 
microtext described herein is well known in the semiconductor industry. 
Photolithography equipment exists for patterning very fine lines into 
resist layers which are etched, either ionically or chemically. 
Alternatively, very fine laser and electron beams may be controlled for 
creating fine line patterns. The advantage of using photolithography is 
that a master photomask may be made and then used to replicate the pattern 
as described in the above-mentioned patent. 
An important consideration is to achieve sufficient optical contrast 
between the microtext and the field so that the text is clearly readable. 
It should be noted that inks are not used and that the resultant card is 
durable in character because of the metallic composition of the recording 
layer. Book cards may now be published containing texts of importance to 
people who desire to carry such texts. For example, religious texts such 
as Buddhist, Christian, Confucian and Moslem texts may all be published 
and carried on a card. With microscope optics, or a magnifying lens of 
appropriate power, the text can be read under ambient light or 
illumination.