Device for holding several leaves together

A device for holding a file of leaves, made of a single piece of resilient material, comprises a flat upper element, a flat lower element, and a hinge-forming part between the upper and lower elements. The upper and lower elements have interlocking components cooperating with each other elastically and removably. The device will grip the file at a corner only. One or both of the upper and lower elements may have on its inner face a non-slip zone facing the upper or/and the lower leaf of the file.

This invention relates to a device for holding several leaves forming a 
file. 
It is usual to bind a certain number of leaves together forming a file 
consituting a document. The fastening means most often used in order to 
hold together a limited number of thin leaves currently consist of 
staples, metal corners, clips or fastenars. 
Such conventional fastening means cause either a local deformation of the 
leaves of the file, or perforations in the leaves. Consequently, the 
conventional fasteners are not entirely satisfactory as regards the 
quality of the bound document, since they directly impair, to a greater or 
lesser extent, the quality and presentation of the leaves of the document. 
Furthermore, conventional fasteners are mainly constructed using a metal 
material. In the case of letters, the presence of metal fasteners may 
constitute a source of disturbance to the operation of the electronic 
machines used in the postal services particularly for sorting of the post. 
From U.K. Pat. Application No. 2 227 047 a metal or plastic fastener for 
leaves is known in the form of a clip. The two parts of the clip are 
connected to one another by a hinge. The placing of the clip onto the file 
of leaves necessitates a fold in the plane of the file so as to permit 
insertion on one side of one part of the clip into a lip for locking of 
the other part. The elastic deformation of the clip when it is fitted into 
place may well create a movement of slippage between the leaves of the 
file thus preventing a regular file from being obtained. 
This invention relates to a holding device or a fastener for several leaves 
forming a file, which causes little or no impairment of the quality and 
presentation of the bound leaves. 
Another object of the invention is to provide a fastener which can be 
constructed of resilient plastic material with a view to replacing the 
conventional metal fasteners for letters for example. 
Another object of the invention is to propose a fastener which offers a 
surface serving as support for designs or text in order to personalise the 
bound documents or in particular to spread advertising messages. 
The holding device or fastener for several leaves forming a file, according 
to the invention, is constructed from a rigid material and comprises: 
- a flat upper element, the inner face of which is adapted to press against 
the first leaf of the file, 
- a flat lower element, the inner face of which is adapted to press against 
the last leaf of the file, 
- a hinge-forming part between the upper and lower elements and arranged 
along a first side of the upper element and along a first side of the 
lower element, said first sides being parallel with a first side of the 
file of the leaves; 
- a primary resilient interlocking component on the inner face and along a 
second side of the upper element, said second side being parallel with a 
side contiguous to the first side of the file, 
- a secondary resilient interlocking component on the inner face along a 
second side of the lower element corresponding to the second side of the 
upper element, 
said primary and secondary resilient interlocking components co-operating 
with one another removably so as to hold the upper and lower elements in 
assembled position, gripping and locking the leaves of the file. 
According to one embodiment of the invention, the hinge-forming part is 
integral with the upper and lower elements and constitutes a bending zone 
between the upper element and the lower element. 
On the side where the hinge-forming part is located, the upper and lower 
elements may comprise other resilient interlocking components, so as to be 
able to exert on the leaves of the file a pressure distributed in balanced 
manner over the inner faces of the upper and lower elements respectively. 
Preferably, in order to avoid slippage of the first leaf and of the last 
leaf with respect to the upper and lower elements of the device in 
assembled position, at least one inner face of said upper and lower 
elements is advantageously rendered non-slip. For example, a roughened 
surface or a surface rendered slightly adhesive, or else an additional 
layer in easily deformable material such as a synthetic foam or a spongy 
substance may be provided. 
The deformable additional layer on the inner face of at least one of the 
upper and lower elements offers the possibility of improving the holding 
of files of different thicknesses. The deformable additional layer may be 
of small size compared with the inner face of the corresponding element. 
Indeed, it is sufficient to have one or more spots of deformable material 
which are securely attached to the inner face of the corresponding element 
and which project from said inner face. 
In order to avoid slippage of the leaves, the inner faces of the upper and 
lower elements may present reliefs of complementary shape, for example 
corrugations, projections and hollows, so that the leaves can be locked by 
gripping of the upper and lower elements of the device. 
The device of the invention is preferably constructed in a single piece 
from a resilient synthetic material. Any other resilient material, for 
example metallic materials, may be used for the device of the invention. 
Preferably, the upper and lower elements of the device of the invention are 
thin enough not substantially to increase the overall thickness of the 
bound file while retaining the required mechanical properties.

In the FIGURES, the device of the invention is shown from particular angles 
with the aim of showing its structure more clearly. This is why FIGS. 1 
and 2 show a file of leaves, the last leaf of which is found at the top of 
the file. In other words, the assembly formed by the file and the device 
is turned through 180.degree. from the normal position. 
According to a first embodiment of the invention shown in FIG. 1, the 
holding device for several leaves forming a file 1 comprises a flat upper 
element 2, a flat lower element 3, a bending zone 4 forming a hinge 
between the upper element 2 and lower element 3. 
The upper element 2 and lower element 3 of the device each present a 
substantially triangular shape, the sizes of which are comparable with one 
another. The hinge 4 is located in the vicinity of an angle of the upper 
and lower elements 2, 3. The file of leases 1 presents a corner 
constituted by a first side 5 and a second side 6 forming a right angle 
with respect to one another. The triangular shape of the upper and lower 
elements 2, 3 presents two sides 2a, 3a and 2b, 3b substantially parallel 
with the sides 5 and 6 respectively of the file 1 forming the corner. 
Thus, the device of the invention enables the file 1 to be held while 
taking the exact shape of the corner of the file without creating 
appreciable projections on the sides. 
The hinge 4 is located in the vicinity of the angle of the corner. The 
lower element 3 can be open or closed as indicated by the arrow 7 with 
respect to the upper element 2 by means of the hinge 4. The upper element 
2 presents two resilient interlocking components 8, 9 along the sides 2b 
and 2a respectively and in the vicinity of the angles of the triangle 
other than that close to the hinge 4. The components 8, 9 project 
perpendicularly to the inner face of the upper element 2. 
Preferably, the components 8, 9 present a convex cylindrical surface 
towards the inside of the upper element 2. The convex cylindrical surface 
stops at a height predetermined with respect to the inner face of the 
upper element 2 so as to be able to accommodate the sides 5 and 6 of the 
file of leaves in their thickness. 
In the sides 3a and 3b of the lower element 3 are made two cutaways 10 and 
11 constituting resilient interlocking components and adapted to 
co-operate with the convex cylindrical surfaces of the resilient 
interlocking components 8 and 9 of the upper element 2. 
When one presses on the outer faces of the upper element 2 and of the lower 
element 3, using two fingers of one hand for example, the lower element 3 
is brought towards the upper element 2 by pivoting by means of the hinge 
4. The cutaways 10 and 11 of the lower element 3 encounter the convex 
cylindrical surfaces of the components 8 and 9 of the upper element 2 and, 
with the help of the pressure exerted and of resilient deformation, move 
past said convex cylindrical surfaces so as to be gripped by said convex 
cylindrical surfaces of the resilient interlocking components 8 and 9. 
Thus, the lower element 3 is held flat against the last leaf of the file 1 
and participates in the holding of the leaves of the file with the upper 
element 2. 
It is also possible to provide the interlocking components 8, 9, 10 and 11 
in the form of projections and depressions in a manner similar to 
press-studs. 
The file 1 of leaves held captive by the upper element 2 and lower element 
3 may have a thickness varying between two and about ten or twenty leaves 
to be effectively held. Preferably, the inner face of the upper element 2 
and/or the inner face of the lower element 3, adapted to be in contact 
with the file preferably present separate or interconnected zones 2', 3' 
rendered non-slip with respect to the leaves. These non-slip zones 2', 3' 
may have a greater roughness than the rest of the upper element 2 and 
lower element 3, or may be covered with a slightly adhesive layer so that 
the corresponding element 2 or 3 of the file 1 can be unstuck without 
leaving any trace on the corresponding leaf of the file. 
It is also possible to form said non-slip zones 2', 3' by means of a spongy 
and flexible substance in plastic material, such as a synthetic foam, 
securely attached to the inner face of the corresponding element 2 or 3, 
so that the compression force for holding the leaves of the file 1, 
exerted by the upper element 2 and lower element 3 in assembled position, 
does not vary substantially for different thicknesses of the file 1. This 
therefore permits very effective holding of the leaves. 
Other embodiments of the invention may be envisaged. For example, with 
respect to the embodiment shown in FIG. 1, the resilient interlocking 
components 9, 11 of the upper and lower elements 2, 3 may be replaced by a 
second hinge connecting the upper side 2a and lower side 3a in the same 
manner and on the same side as the hinge 4. This second hinge may also be 
integral with the hinge 4 so as to constitute a continuous side for 
bending between the upper element 2 and lower element 3. 
Preferably, the bending zone 4 may be rendered more flexible in the 
direction of bending, for example by means of longitudinal grooves made in 
the bending zone or by making the depth of said zone thinner compared with 
the upper and lower elements 2, 3. 
It is also possible to envisage the upper and lower elements 2, 3 in a 
shape different from the triangular shape without affecting the operation 
of the device. Another possibility is the elimination of the corner where 
the hinge 4 is located in FIG. 1. In this manner, the device then 
comprises the upper and lower elements 2, 3 in the form of a trapezium. A 
bending zone 4 would then still have to be provided on the side 2a, 3a, 
but in the zone where the interlocking components 9, 11 are found in FIG. 
1. 
FIG. 2 shows another embodiment of the invention with the upper element 2 
and lower element 3 flat and substantially rectangular and connected to 
one another by means of a bending zone 4 along one side 2a, 3a of the 
rectangles. The resilient means used for assembly of the upper and lower 
elements 2, 3 are slightly different from those used in the embodiment 
shown in FIG. 1. 
On the first side 2b of the upper element 2 parallel with the side 6 of the 
file 1, the upper element 2 presents two longitudinal lips 12 projecting 
towards its inner face. The facing ends of the lips 12 each present a 
depression 13. 
The corresponding side 3b of the lower element 3 presents a form 
complementary to the side 2b of the upper element 2. The side 3b comprises 
a longitudinal protuberance 14, the two ends 15 of which are convex and 
rounded, so that the turning back of the lower element 3 by means of the 
hinge 4 and in the direction of the arrow 16 causes a slight resilient 
deformation of the ends 15 of the longitudinal protuberance 14 and of the 
facing ends of the lips 12. With the device in assembled position, the 
rounded convex ends 15 of the longitudinal protuberance 14 of the lower 
element 3 are accommodated in the depressions 13 of the facing ends of the 
lips 12 of the upper element 2. The same resilient interlocking means may 
be used for the sides 2a, 3a of the upper and lower elements 2, 3 in the 
extension of the bending zone 4 parallel with the side 5 of the file 1. 
As for the first embodiment shown in FIG. 1, at least one of the upper and 
lower elements 2, 3 presents on its inner face non-slip zones 2', 3' in 
order to hold the leaves of the file 1 in place. 
In the embodiment shown in FIG. 3, the device comprises a hinge 4 extending 
along the entire length of the side 2a, 3a of the upper and lower 
elements. Otherwise, this embodiment is comparable with that shown in FIG. 
2. 
In FIG. 3, the device of the invention is in open position with the upper 
element 2 and lower element 3 substantially coplanar. The closure of the 
device is performed by pivoting along the hinge 4 as shown by the arrow 
17. A primary resilient interlocking component 18 of trapezoidal shape 
co-operates with a secondary resilient interlocking component 19 
delimiting a recess for the primary component 18, the entry into the 
recess being provided with inclined faces 20 so as to facilitate the 
insertion of the primary trapezoidal component 18 into the recess. 
In all of the embodiments described above, the device of the invention is 
put into place simply by pressing on the two outer faces of the upper and 
lower elements 2, 3 without necessitating the resilient deformation of 
said elements; the resilient deformation takes place at the level of the 
interlocking components.