EP0732223A2

EP0732223A2 - Envelope for transparencies for overhead projectors

Info

Publication number: EP0732223A2
Application number: EP96102143A
Authority: EP
Inventors: Vincenzo Rispoli
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1995-03-16
Filing date: 1996-02-14
Publication date: 1996-09-18
Also published as: NO961054L; ITMI950180V0; NO961054D0; EP0732223A3; ITMI950180U1; IT236739Y1

Abstract

Envelope for transparencies for overhead projectors, said envelope comprising a substantially rectangular pocket comprising two sheets of transparent plastic material having two longitudinal side edges connected by shorter side edges, which is open at least along one side edge for the insertion therebetween of the transparency to be presented, at least one opaque flap being attached to the envelope in a foldable manner parallel to one of the longitudinal side edges of the pocket, said flap being spaced a distance from the longitudinal side edge such that in the unfolded position the flap covers the longitudinal side edge and in the folded position it exposes said longitudinal side edge, characterized in that at least one sheet of transparent plastic material has a border frame printed with transparent or opaque ink.

Useful to improve the appearance of the transparencies when they are projected, compared to the projection of transparencies inserted in non-bordered envelopes. It can be used indefinitely, due to the fact that said border frame is permanently printed on the envelope rather than on each transparency.

Description

FIELD OF THE INVENTION

The present invention relates to an envelope for transparencies for overhead projectors, said envelope comprising two sheets of transparent plastic material, at least one sheet having a border frame printed with transparent or opaque ink.

BACKGROUND OF THE ART

It is 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 US 3,875,693, the transparency is put into a frame of cardboard, paper or similar material. The frame is meant to mask the illumination gaps formed in the periphery of the such transparency. The frame can also be used for making notes and other memoranda needed by lecturer. The disadvantage of these framed transparencies is that they are bulky and therefore difficult to be stored and transported 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, disclosed in SE 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 transparencies to be presented. These envelopes are simple to be handled, stored and transported as the outer dimensions of the pocket are conformed to those of standard binders and files. After lecture, the envelope can be replaced with another one. However, this envelope is disadvantageous in that peripheral illumination is not masked; 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 for overhead projectors.
EP 47,306 describes an envelope for transparencies for overhead projectors comprising a substantially rectangular pocket of transparent plastic sheet material which is open at least along one side edge for insertion therebetween of the transparency to be presented. Being antistatic and antiadhesion treated, it does not attract dust, does not adhere to other envelopes and does not pick up text from the transparency.
To improve the appearance of the transparencies with black texts when they are projected, transparencies on which a colored border frame is printed with transparent or opaque ink are generally used, as described in US 5,371,560. A transparency containing a printed border frame, colored or not colored, is also useful to give a more clear projection of the content of the transparency if compared with transparency not having such border frame. Said bordered transparencies can be used in two different ways to obtain the same result. In fact, the text to be presented by projection can be printed: a) directly on a border frame transparency which is then inserted into the envelope for transparencies or b) on a non-bordered transparency which is then inserted into the envelope for transparencies, together with a border frame transparency. However, both utilizations have a disadvantage: in fact, in case a), when the text copied on the transparency is obsolete, the border frame transparency can no more be used. In case b), a couple of transparencies, one bordered and one non-bordered, must always be used for each envelope. The continuous contact inside the envelope between the couple of transparencies can cause a damage to the border frame transparency because it may pick up part of the text printed on the non-bordered transparency. Both utilizations described in case a) and b) cause a considerable waste of money.
It might be useful to provide border frames for transparencies to be used in overhead projectors which have not the disadvantages of the prior art border frames discussed above, are simple to be handled and also of reliable design and function.

SUMMARY OF THE INVENTION

The present invention relates to an envelope for transparencies for overhead projectors and like projecting apparatus, said envelope comprising a substantially rectangular pocket which comprises two sheets of transparent plastic material having two longitudinal side edges connected by shorter side edges, which is open at least along one side edge for the insertion therebetween of the transparency to be presented, at least one opaque flap being attached to the envelope in a foldable manner parallel to one of the longitudinal side edges of the pocket, said flap being spaced a distance from the longitudinal side edge such that in the unfolded position the flap covers the longitudinal side edge and in the folded position it exposes said longitudinal side edge, characterized in that at least one sheet of transparent plastic material has a border frame printed with transparent or opaque ink.
The envelope of the present invention is useful to improve the appearance of the transparencies when they are projected, compared to the projection of transparencies inserted in non-bordered envelopes.
The envelope with printed border frame of the present invention can be used indefinitely, due to the fact that said border frame is permanently printed on the envelope rather than on each transparency.

DRAWINGS

Figure 1 is a perspective view of an overhead projector on the plane of which there is placed an envelope according to the present invention in an unfolded position;
Figure 2 is a plan view of the envelope in a folded position.
Figure 3 is a section view on line III-III of Figure 2.
Figure 4 is a plan view of the envelope in an unfolded position.
Figure 5 is a section view on line V-V of Figure 4.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows an overhead projector (1) of the kind used for educational and lecturing purposes for the projection of images on a screen. An envelope (2) according to the invention is placed on the horizontal stage of the overhead projector and said envelope encloses a transparency (3) to be presented. The position of said transparency (3) in said envelope is shown in Figure 3. The envelope (2) and the transparency (3) are substantially rectangular and the envelope is slightly larger than the transparency both in width and preferably also in length. In the embodiment shown in Figures 1, 2 and 3, the envelope (2) comprises a pocket which consists of two sheets (4,5) of transparent plastic material, preferably a polyester film of about from 1.8 to 2 mils (0.04572 to 0.0508 mm), said sheets being joined together at least along one side or formed by folding a large sheet to form the faces on the envelope. Preferably, the plastic material is antistatic and antiadhesion treated in order not to attract dust and be such that text on transparency (3) is not picked up by the sheets (4,5) of the pocket. Along one longitudinal side, preferably the longitudinal side not joining together the two sheets, the envelope may be provided with punched holes (6) to permit storage in a binder, file or the like. Preferably, for an easier insertion of the transparency into the envelope, this is open along two contiguous sides, one of which is the longitudinal one provided with the punched holes (6).
Two opaque, substantially rectangular elongated flaps (7,8) are attached in a foldable manner to the outer side of one sheet (5) of the pocket or envelope. The flaps are made of a material which accepts text written by conventional writing instruments. Further, the flaps are connected to the sheet (5) of the envelope such that they can be readily folded from the unfolded position, shown in Figure 1, to the folded position, shown in Figures 2 and 3, and viceversa. The flaps (7,8) are attached to the sheet (5) by flexible adhesive tapes or by a foldable weld or flute (9). Naturally, the flaps (7,8) can be connected to the sheet (5) in some other manner, provided that it produces a so-called hinge effect. In the unfolded position, the flap (7) covers the punched holes (6) so that they are not projected onto the screen during presentation.
In the unfolded position, the envelope has a surface larger than the stage of the overhead projector so that said stage is entirely covered by the expanded envelope.
On one sheet (4) of the pocket, preferably on the sheet different from the one the flaps (7,8) are attached to, a border frame (10) is printed with a transparent or opaque ink. Preferably, the border frame is colored, to improve the appearance of the transparencies with black texts when they are projected. The printed border frame (10) may be of various design, shape and colors. For example, it can be a simple border frame, or it can reproduce a trademark name, a company name, a particular design having different shape and color (yellow, green, blue, red), and the like. Said border frame can be customized in various ways according to different situations. When the flaps (7,8) are in the unfolded position, see Figure 4, the printed border frame (10) is completely visible.
The shape and dimensions of such printed border frame (10) are such as to cover less than 20%, preferably less than 10% of the sheet (4), thus allowing the transparency inserted into the pocket to have an area inside said border frame of at least 80%, preferably at least 90%, of the total area of the transparency, said area inside the border frame being available for projecting the text printed onto the transparency.
The border frame can be printed with various printing processes known in the art. For example, it can be printed on the plastic film, before forming the envelope, using a rotogravure printing process. Otherwise, it can be printed on one side of the envelope, when it is already formed, using a printing process such as a silk screen process or an offset printing process, the latter being preferred in terms of speed.
The flaps according to the proposed embodiment of the invention may be of course arranged either on the front side of the envelope, as shown in the drawings, or on the back side of the envelope. Moreover, the shape of the flaps can be modified within the scope of the invention.
The two flaps, when are in the folded position, can cover only part of the transparency contained in the envelope, as disclosed in EP 47,306, or can substantially cover all the surface of the transparency contained in the envelope, as described in EP 627,300, wherein "substantially" in this invention means that the flaps cover at least 95% of the surface of the transparency.
In other embodiments of the invention, the envelope has only one flap which is attached to the longitudinal side edge which may be provided with punched holes and is so large that in the unfolded position the envelope covers the stage of the overhead projector.
Further embodiments of the envelope are those described in EP 47,306.

Claims

An envelope for transparencies for overhead projectors, said envelope comprising a substantially rectangular pocket comprising two sheets of transparent plastic material having two longitudinal side edges connected by shorter side edges, which is open at least along one side edge for the insertion therebetween of the transparency to be presented, at least one opaque flap being attached to the envelope in a foldable manner parallel to one of the longitudinal side edges of the pocket, said flap being spaced a distance from the longitudinal side edge such that in the unfolded position the flap covers the longitudinal side edge and in the folded position it exposes said longitudinal side edge, characterized in that at least one sheet of transparent plastic material has a border frame printed with transparent or opaque ink.
An envelope according to claim 1, wherein said border frame is colored.
An envelope according to claim 1, wherein said border frame is such that it covers less than 20% of the total area of the sheet.
An envelope according to claim 1, wherein said border frame is such that it covers less than 10% of the total area of the sheet.
An envelope according to claim 1, wherein said longitudinal side edge of said pocket adjacent said opaque flap is provided with punched holes for storage of the envelope in a binder.
An envelope according to claim 1, wherein the pocket is open along two adjoining side edges, one of which is the longitudinal side edge provided with punched holes.
An envelope according to claim 1, wherein the envelope has two flaps, each one of which is provided along a respective one of said longitudinal side edge of the pocket.
An envelope according to claim 1, wherein the flap is attached to the sheet by a flexible adhesive tape or a foldable weld or flute.