Light blocking transparency assembly

A light blocking transparency assembly comprises a single sheet of transparency film and two foldable opaque flaps. The flaps overlap when in their folded position. The inventive construction provides improved feedability of the assembly through a variety of imaging devices.

FIELD OF THE INVENTION 
The present invention relates to films and film constructions having an 
image thereon (transparencies) for use with overhead projectors. In 
particular, the invention relates to such films and film assemblies which 
are particularly suitable for imaging in copiers and other imaging 
devices. 
BACKGROUND OF THE INVENTION 
Transparencies are transparent or translucent films which may be clear or 
colored and include textual or graphical data. The data on the 
transparency may be projected on a distant surface or screen, usually in 
enlarged form, by an overhead projector so that the data may be observed 
by a large number of people at once. A typical overhead projector includes 
a stage upon which the transparency may be placed. A light from a source 
within the projector is directed through the stage and the transparency to 
a lens system which focuses the light, and an image of the data contained 
on the transparency, on the distant viewing surface. 
Films for use with overhead projectors have been developed and improved 
continuously over the years. Early transparencies were merely clear film 
on which an image could be drawn with, for example, a suitable pen. Later 
improvements included ink receptive layers that were coated on the films 
to improve certain characteristics of the film, such as drying, image 
spreading, and smudging. For example, U.S. Pat. No. 4,379,804 to Eisele et 
al. describes a two-layer film construction which provides an 
ink-receptive layer on the film. Such a construction can be used in ink 
jet printers of the type exemplified by the Hewlett Packard Company's 
DeskJet 660C. 
Of course, other film constructions and imaging methods may also be used to 
generate transparencies. For example, U.S. Pat. No. 5,310,591 to Dodge et 
al. describes an image receptive sheet suitable for use in a plain paper 
copier; U.S. Pat. No. 5,306,686 to Patel et al. describes a thermally 
imageable sheet; and U.S. Pat. No. 5,298,309 to Carls et al. describes a 
sheet suitable for use in a color copier, such as the Canon CLC 500. 
In addition to film constructions intended to improve the use of 
transparency films with particular types of imaging devices, other 
inventive constructions have been developed to make the use of overhead 
transparencies easier. For example, U.S. Pat. No. 4,402,585 to Gardlund 
discloses a transparent film envelope having foldable flaps attached to 
its edges, and having perforated holes down one edge. A previously imaged 
transparency can be inserted in the envelope for protection, and with the 
flaps in the folded position the perforations can be used to store the 
assembly, for example, in a three ring binder. In the unfolded position, 
the flaps block unwanted light from passing the edges of the transparency 
and reaching the screen. Additionally, the flaps may also be used for the 
user's presentation notes. In some embodiments, the flaps extend 
substantially over all the area of the transparency, thus conferring the 
additional benefit of enabling the transparency to be easily viewed when 
in storage. Other inventions have improved on features of U.S. Pat. No. 
4,402,585. For example U.S. Pat. No. 5,237,355 to Kiehne et al. describes 
an envelope with increased flexibility. 
Transparency films having attachments directly on the imageable film are 
also known. For example, Minnesota Mining and Manufacturing Company's 
product PP2410 is a film intended for use in a Xerographic-type copier 
that has a sheet of paper of essentially the same size as the carrier film 
adhesively bonded to the film along one edge. The adhesive is of the 
repositionable or removable type, thus allowing the paper sheet to be 
removed easily for viewing the imaged film while leaving little or no 
adhesive residue on the film. However, there is no provision in the 
adhesive bonding to allow flexibility between the carrier sheet and the 
paper sheet, and in fact such flexibility might be detrimental to the 
proper functioning of the assembly. 
Other attachments to imageable films include a narrow stripe of paper or 
other functionally opaque material which is adhered to the carrier film 
with a repositionable or removable adhesive. The stripe is intended to 
indicate to the optical sensor mechanism of a copying machine that a copy 
cycle is to be initiated, because it is known that clear carrier film will 
not function in certain copying machines due to the inability of the 
machine to detect the presence of the transparent film. A striped carrier 
film of this type is supplied by 3M as PP 2200 copier film. 
A recent invention described in U.S. Pat. No. 5,319,400 to Herbert et al. 
has made a large improvement in imageable film assemblies for use with 
overhead projectors. Herbert et al. describes an imageable film assembly 
suitable for use in an ink jet printer or a copier, having perforations 
along one edge of the film (for storage in a binder, for example), and 
flexible light blocking flaps attached directly to the imageable film. The 
Herbert et al. assembly confers the combined advantages of reduced weight 
and improved storability (resulting from the elimination of a protective 
storage envelope), extraneous light blocking and the ability to append 
notes on the attached flaps, and the ability to pass the entire assembly 
through an imaging device such as a copier or printer. 
While Herbert et al. represents a large step forward in the art, additional 
improvements are desired. Recently, particular attention has been paid to 
improving the feedability of the imageable film assemblies. Feedability of 
an assembly relates to the ability of the assembly to pass through an 
imaging device without mis-feeding or jamming in the imaging devices, and 
is considered a very important product property by the user. 
It is known that in certain devices, particularly high speed copiers and 
certain ink jet printers, that feed failures and jamming occur with film 
assemblies like those of Herbert et al. For example, if an imaging 
assembly of this type is directed around a curve in the feed path of a 
high speed copier there is a strong possibility that the free edge of the 
flap on the trailing edge of the assembly may separate from the imageable 
film and catch on a protruding part of the copier, thereby causing a feed 
failure. Similarly certain ink jet printers have internal grids intended 
to guide and protect the imageable media used in the printer. It has been 
found that free corners of the light blocking flaps can catch on these 
internal grids and result in a feed failure and damage to the imageable 
assembly. Because mis-feeds and jams result in wasted products, lost time, 
and end user dissatisfaction, it is desirable to avoid these problems. 
As the use of overhead projectors and transparency assemblies increases, it 
is also desirable to have only a small range of imageable film assembly 
product types which work with a wide variety of imaging devices, as this 
reduces manufacturing complexity, improves the economics of product 
manufacture, and lessens the risk of the user mismatching the product and 
imaging device. There thus exists a need for an improved imageable film 
assembly which has improved feedability and which is suitable for use in a 
wide variety of imaging devices, while at the same time maintaining the 
advantages of prior film assemblies, such as disclosed in Herbert et al. 
SUMMARY OF THE INVENTION 
The present invention describes an imageable film assembly which exhibits 
improved feedability over the constructions of U.S. Pat. No. 5,319,400. In 
the preferred embodiment of this invention a first opaque flap is caused 
to overlap a second opaque flap in such a manner that the edge of the 
overlying flap is substantially removed from the central region of the 
construction. This has been found to enable superior feeding properties to 
be obtained in both copiers and ink jet printers.

It should be noted that the Figures exhibit some exaggeration of material 
dimensions to more readily illustrate the relationships between the 
various components. 
DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 illustrates a preferred embodiment of the inventive imageable film 
assembly 12. Arrow 20 shows the direction of motion of the assembly 12 
through an imaging device (not shown) such as a photocopier. Assembly 12 
includes a carrier film 24. Carrier film 24 is transparent to at least one 
region of the visible light spectrum, and possesses sufficient strength to 
pass through an imaging device. Biaxially oriented 
Poly(ethyleneterephthalate) films having a thickness in the range of 75 to 
150 microns have been used commercially for the intended purpose and have 
been found to have acceptable properties. 
Associated with the carrier film 24 is an imageable surface 22, shown in 
FIG. 1 as a distinct layer. A distinct layer, while able to confer 
additional valuable properties to the image quality of assembly 12, is not 
essential. For example an uncoated surface of carrier film 24, may 
function satisfactorily in certain applications, such as in a copier, when 
toner adhesion is not critical to the image quality. 
In FIG. 1, assembly 12 is illustrated as having perforations 26 along one 
edge of carrier film 24. Perforations 26 are suitable for inserting the 
assembly 12 in commercially available protective covers such as three-ring 
binders. Perforations 26 could be on any edge of film 24, or could be 
omitted from the assembly 12 altogether. If assembly 12 is supplied 
without perforations 26, such perforations may be made after imaging, if 
desired, by the user. 
As shown in FIG. 1, assembly 12 has a leading edge 28 that is the first 
edge to enter and exit the imaging device, and a trailing edge 30 that is 
the last edge to enter and exit the imaging device. Associated with edges 
28 and 30 are a leading flap 32 and a trailing flap 34, respectively. 
Flaps 32 and 34 are made of a functionally opaque or light-absorbing 
material. A preferred material is paper, but the material could also be a 
light-absorbing film, a pigment-containing film, a translucent film or 
other material whose primary property is an ability to prevent unwanted 
light from reaching the viewing screen. 
Depending upon the selected material, flaps 32 and 34 are normally in the 
range of 50 to 250 microns in thickness, and are attached to carrier film 
24 by means of flexible tape hinges 38 and 40. These hinges may be made of 
paper, cellulose acetate tape, or preferably poly(ethyleneterephthalate) 
tape. Tape suitable for use in this purpose is disclosed in U.S. Pat. No. 
5,237,355. The thickness of hinges 38 and 40 is preferably on the order of 
tens of microns, and the adhesive (not shown) used to bond the components 
together is preferably permanent in the sense that it is not intended for 
repeated removal and readhesion. 
The disposition of the flaps 32 and 34 with respect to the carrier film 24 
is of particular importance to the functioning of the invention. It is 
essential that flaps 32 and 34 create an area of overlap 36, in which the 
trailing flap 34 is positioned between the leading flap 32 and the carrier 
film 24, as shown in FIGS. 1 and 2. As best seen in FIG. 2, trailing flap 
34 is partially overlain by leading flap 32, thereby creating overlap 
portion 36. 
FIG. 3 illustrates the importance of overlap portion 36, and particularly 
the importance of leading flap 32 overlapping trailing flap 34. In FIG. 3, 
an assembly 12' typical of the prior art is traversing through a portion 
of a photocopying machine. The construction of assembly 12' is identical 
in all respects to the assembly 12 shown in FIGS. 1 and 2, except that 
flaps 32' and 34' do not overlap. The direction of motion is indicated by 
arrow 20, and the curve of the carrier film 24 is intended to indicate 
that the film is traversing a curved path through the copying machine. 
Only a generic internal component 42 of the copier is shown, to illustrate 
the most common cause of mis-feeding. 
As illustrated in FIG. 3, the inherent rigidity of flap 34' has caused it 
to separate from the carrier film 24, to such an extent that copier 
component 42 will catch leading edge 43' of trailing flap 34' and will 
impede further progress of flap 34' through the copying machine. As a 
result of this impedance, one of several outcomes may result. Flap 34' may 
be forced to detach from the carrier film 24. Flap 34' may be folded back 
so that it trails the carrier film 24. Flap 34' may buckle and prevent any 
further movement of the assembly 12' through the copier. All of these 
possible outcomes are undesirable, as they all cause damage to the 
assembly 12, inconvenience the user, and potentially damage the copier. 
FIG. 4 shows the inventive assembly 12 of FIGS. 1 and 2 traversing through 
a portion of a photocopier identical to that shown in FIG. 3. As 
illustrated by FIG. 4, if the trailing flap 34 is overlaid by leading flap 
32, undesired separation of trailing flap 34 from carrier film 24 is 
prevented. Direction of motion is again shown by arrow 20. As can be seen 
from the Figure, leading flap 32 overlaps trailing flap 34 and has the 
effect of preventing copier feature 42 from catching on the leading edge 
43 of trailing flap 34, thereby assisting in smooth and trouble free 
passage of assembly 12 through the copier. 
FIG. 5 shows an alternative embodiment of the inventive assembly having a 
single flap rather than two flaps, as shown in FIGS. 1-4. The assembly of 
FIG. 5 is made of materials like those used in the embodiment described in 
FIGS. 1-4 and comprises a carrier sheet 44 having an image receptive 
surface or coating 46. Flexibly attached to the carrier sheet 44 by a 
hinge 48 is a flap 50. Hinge 48 is adjacent leading edge 54 and is 
attached in a manner like that described above for hinges 38, 40 in FIGS. 
1-4. That is, the adhesive used to bond the flap to the carrier web is not 
intended for repeated removal and readhesion as is the case with certain 
products, for example the previously mentioned Plain Paper Copier Film 
PP2410 supplied by 3M Company. Perforations 58, are shown adjacent 
trailing edge 56, but as described for perforations 26 in FIGS. 1-4, 
perforations 58 could be placed adjacent any desired edge, or could be 
omitted from the assembly entirely. 
An essential difference between the embodiment of FIG. 5 and the embodiment 
described in FIGS. 1-4 is, of course, the absence of a second flap and 
therefore the absence of an overlap area. However, the embodiment of FIG. 
5 confers the same advantages as the embodiment of FIGS. 1-4 when moved in 
the direction of arrow 20 through an imaging device such as a photocopier. 
By feeding the hinged end of flap 50 through the imaging device first, the 
free end of flap 50 will not catch on any protrusions within the imaging 
device. 
FIG. 6 shows an alternative embodiment of the invention very similar to the 
embodiment of FIGS. 1-4. The components of the embodiment of FIG. 6 are 
similar to components described in the previous embodiments. The 
embodiment of FIG. 6 has an additional coating 60 added to the surface of 
the carrier film 24 adjacent to flaps 32, 34. Coating 60 is selected to 
provide a high coefficient of friction between carrier film 24 and flaps 
32 and 34 and prevent movement of flaps 32, 34 relative to carrier film 
24. Preferably, coating 60 provides a coefficient of friction of at least 
0.3 with flaps 32 and 34. If desired, coating 60 may comprise the same 
material as imaging coating 22. Using the same material to coat each side 
of carrier film 24 may be desired to prevent curling of the carrier film 
during imaging. 
FIG. 7 shows an embodiment of the invention found particularly suitable for 
use in ink jet printers. A carrier sheet 24 has on one side an image 
receptive coating or surface 22, and on the other side, flaps 32 and 34 
flexibly attached to the carrier sheet by tape hinges 38 and 40. The 
direction of motion through the imaging device is indicated by arrow 20, 
although it is expected that this same construction would feed 
satisfactorily in the opposite direction. A center line C--C is shown, 
being equidistant from edges 28 and 30. Flap 32 is shown substantially 
overlapping flap 34, so that free edge 74 of flap 32 is substantially 
nearer to carrier sheet edge 30 than it is to edge 28. In this embodiment 
the flap 34 is shown also extending substantially past the center line 
C--C towards the assembly edge 28. This is not a necessary condition, it 
only being necessary that edge 74 of flap 34 be substantially closer to 
edge 30 than to edge 28. It is possible for edge 76 of the underlying flap 
34 to be closer to carrier sheet edge 30 than to carrier sheet edge 28, 
provided that it is still substantially overlapped by flap 32. It is also 
possible in this embodiment, designed for working in certain ink jet 
printers, for the overlap to be in the reverse direction. That is, flap 34 
may overlap flap 32, the major requirement being that the exposed edge, 
now edge 76, be substantially removed from the region of the center line 
C--C. 
It will be noted that the construction of the assembly of FIG. 7 is very 
much like that of the assembly of FIGS. 1-4, and in fact the construction 
of the two assemblies could be identical. In the assembly of FIGS. 1-4, it 
is important only that leading flap 32 overlaps trailing flap 34 such that 
free edge 43 of trailing flap 34 is covered and prevented from catching on 
any protrusions within the imaging device. The area of overlap 36 between 
flaps 32 and 34 can occur at any point, so long as this condition is 
satisfied. 
In contrast, in the assembly of FIG. 7, it is important that the free edge 
of the overlapping flap be removed from the central region C--C of the 
construction. This is important because it is common for ink jet printers 
to have internal guide grids which may otherwise catch on the free edge of 
the overlapping flap. A common guide grid 80 is illustrated in FIG. 8. 
Grid 80 has diagonal members 82 which are intended to smooth the imaging 
material as it moves through the printer. Diagonal members 82 in portion 
84 of grid 80 work to pull the imaging material toward outer edge 86, 
while portion 88 of grid 80 works to pull the imaging material toward 
outer edge 90. In this manner, the imaging material is flattened and 
smoothed. In the embodiment of FIGS. 7 and 8, the free edge 74 of 
overlying flap 32 is urged by grid 80 away from its hinged edge, thereby 
smoothing the flap 32 and preventing a mis-feed of the imaging assembly. 
If free edge 74 were on the opposite side of center line C--C from that 
shown in FIG. 8 (or if flaps 32 and 34 were not overlapped), grid 80 could 
catch free edge 74 and force it back toward assembly edge 28, thereby 
causing flap 32 to fold back upon itself or buckle. In such an occurrence, 
the assembly is damaged and perhaps rendered useless. 
It can clearly be seen that the inventive assemblies provide superior 
feedability when compared to prior art assemblies. The following examples 
illustrate the improvement: 
EXAMPLE 1 
Example 1 illustrates the use of the inventive assembly of FIG. 7 in ink 
jet printers. Two sets of samples were constructed. Both sets of samples 
used identical imaging film suitable for ink jet printers. The standard 
assembly had flaps 37/8 inches wide, made of 60 lb. paper obtained from 
Consolidated Paper Co. The inventive assembly was made of similar 
materials except that the flaps were made to be 43/8 inches wide. The 
inventive assembly thus had an overlap of the flaps of approximately 7/8 
inch, whereas on the standard sample there was a gap of approximately 1/8 
inch between the flaps. Ten sheets of the standard material were fed 
through five ink jet printers (three Hewlett-Packard 1200C printers, and 
two Hewlett-Packard 1600C printers). Of a total of 50 standard assemblies 
fed into the printers, 27 feeding defects were observed, mostly bending of 
the leading corners of the flaps. Four of the standard assemblies would 
not pass through the printers at all. When the inventive assemblies were 
subjected to the same test, in the same printers, no feeding defects were 
observed in 50 samples. 
EXAMPLE 2 
Two sets of samples were constructed in a manner like that in Example 1, 
except that an imaging film suitable for imaging in an electrophotographic 
copier was used as the carrier sheet. The dimensions of the final 
assemblies were the same as those of the assemblies of Example 1. Care was 
taken to ensure that the flap attached to the leading edge of the 
inventive assembly overlapped the flap attached to the trailing edge. 
Feeding the standard assemblies through three copiers (a Lanier 6360, a 
Xerox 5065, and a Xerox 1090) resulted in five out of five feed failures 
of the standard construction in each of the three copiers, or a 100% feed 
failure rate. When the inventive assemblies of were used, ten out of ten 
inventive assemblies successfully fed through the Lanier 6360 copier, and 
five out of five assemblies fed through the Xerox copiers, producing a 0% 
feed failure rate. 
As clearly illustrated by the Examples, the inventive assemblies produce 
far superior feedability through both ink jet printers and photocopiers. 
The inventive assemblies permit a small range of assembly types to work 
with a variety of imaging devices, thereby improving the economics of 
product manufacture and lessening the risk of the user mismatching the 
product and the imaging device.