Optics: image projectors – Picture carrier
Patent
1981-02-25
1983-09-06
Haroian, Harry N.
Optics: image projectors
Picture carrier
353DIG5, G03B 2111, F03B 2300
Patent
active
044025858
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to an envelope for transparencies for overhead projectors and like projecting apparatuses, said envelope comprising a substantially rectangular pocket of transparent plastic sheet material which is open at least along one side edge for insertion of the transparency to be presented therebetween.
2. Background Art
It is previously known, particularly in giving lectures and in teaching, to make use of transparencies which are presented to the viewers on a screen by means of an overhead projector. To realize a professional presentation of these transparencies there have been developed various types of envelopes for storage and presentation of the transparencies. In one type of envelope, see for example U.S. Pat. No. 3,875,693, the transparency is framed in a frame of carton, paperboard or like material. The frame is meant to mask the illumination gaps formed about the periphery of the transparency proper. The frame can also be used for making the notes and other memoranda needed by the lecturer. The disadvantage of these framed transparencies is that they will be bulky and therefore difficult to store and transport since they do not fit standard binders or files and shelves, respectively. Moreover it is troublesome to attach the transparencies to the frames. In another type of envelope, cf. for example Swedish printed patent application No. 382,266, the envelope is a plastic sheet pocket with punched holes along one side, said plastic pocket being open at the top for insertion of the transparency to be presented. These envelopes are simple to handle, store and transport as the outer dimensions of the plastic sheet pocket are conformed to those of standard binders or files. Moreover, the transparency is protected by the envelope, and at the presentation written notes can be made on the envelope, and after the lecture the envelope can be replaced by another one. However this envelope is disadvantageous in that peripheral illumination is not masked and that the lecturer can not make written notes on the envelope without these notes being also shown on the screen. Further, the contours of the punched holes are also shown on the screen. This envelope therefore yields a total picture on the screen, which in no way satisfies the requirements placed on a professional presentation of transparencies of overhead projectors.
Further examples of covers or envelopes for storage of transparencies for overhead projectors are disclosed by U.S. Pat. Nos. 3,253,358; 3,264,936; 3,438,702; 3,438,703; 3,524,703; 3,536,393; 3,537,792; 3,544,211 and 3,600,079 and Swedish printed patent application No. 346,166. It is easily realized that the covers and envelopes according to these publications are complicated to handle and display many of the drawbacks mentioned above when prior art envelopes were described. Besides, most of those patents presuppose that the transparencies shall be presented in a definite sequence and the covers of most transparencies are difficult to exchange.
The object of the present invention is to provide an envelope of the type mentioned in the introduction, said envelope eliminating the disadvantages of the prior art envelopes and being simple to handle, store and transport and also of reliable design and function.
This object is realized by the present invention in that at least one opaque flap is attached in a foldable manner along one of the longitudinal side edges of the pocket, said flap being attached to and spaced a distance from the longitudinal edge such that holes may be punched in the sheet material along said side edge between the flap and said edge and such that in the unfolded position the flap covers the longitudinal side edge and in the folded position it exposes said longitudinal side edge and any holes to permit storage in a binder, file or the like.
Preferred embodiments of the invention have been given the characteristic features appearing from the subclaims.
The advantages gained by the envelope according to the invention are numerous.
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Alexander Cruzan
Barnes John C.
Haroian Harry N.
Minnesota & Mining Manufacturing Company
Sell Donald M.
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