[0001] This invention relates to a paper-retaining device and, in particular, such a device
adapted to releasably retain pieces of hole-punched paper.
[0002] Paper-retaining devices, such as ring-binder folders or lever-arch type files, have
been available for a long time. Such devices include ring-binder mechanisms or lever-arch
type file mechanisms, and are adapted to releasably retain pieces of hole-punched
paper in rings of the ring-binder mechanisms or lever-arch type file mechanisms, and
to allow such paper to be retrieved therefrom.
[0003] It is generally known that when such a paper-retaining device holding a large amount
of paper stands with its covers in an upright position, the weight of the paper may
be sufficient to bring down the device. In addition, it is also generally known that
for a right-handed writer, it is ergonomically convenient to slightly tilt up the
top right hand corner of the piece of paper to be written. Such is however not possible
in the case of a conventional paper-retaining device, as this would mean that the
lower left hand corner of the front cover of the opened paper-retaining device will
point towards the user and may even extend beyond the lower end of the writing table,
thus causing discomfort and even danger to the user.
[0004] It is thus an object to provide a substrate for a paper-retaining device and a paper-retaining
device in which at least one of the above shortcomings is mitigated, or at least to
provide a useful alternative to the public.
[0005] According to a first aspect of the present invention, there is provided a substrate
for a paper-retaining device, including a spine portion, a first cover member and
a second cover member, wherein each of said spine portion, said first cover member
and said second cover member includes a respective lower edge, wherein said first
cover member is pivotably engaged with and movable relative to said spine portion
about a first edge, and wherein said second cover member is pivotably engaged with
and movable relative to said spine portion about a second edge, characterized in that
an angle subtended between said lower edge of said first cover member and said first
edge is less than 90°.
[0006] According to a second aspect of the present invention, there is provided a paper-retaining
device including a substrate fixedly engaged with means for releasably retaining at
least a piece of paper, said substrate including a spine portion, a first cover member
and a second cover member, wherein each of said spine portion, said first cover member
and said second cover member includes a respective lower edge, wherein said first
cover member is pivotably engaged with and movable relative to said spine portion
about a first edge, and wherein said second cover member is pivotably engaged with
and movable relative to said spine portion about a second edge, characterized in that
an angle subtended between said lower edge of said first cover member and said first
edge is less than 90°.
[0007] According to a third aspect of the present invention, there is provided a substrate
for a paper-retaining device, including a spine portion, a first cover member and
a second cover member, wherein each of said spine portion, said first cover member
and said second cover member includes a respective lower edge, characterized in that
when said spine portion and said first cover member occupy a same plane, the lower
edge of said spine portion and the lower edge of said first cover member subtend an
angle of less than 180°.
[0008] According to a fourth aspect of the present invention, there is provided a paper-retaining
device including a substrate fixedly engaged with means for releasably retaining at
least a piece of paper, said substrate including a spine portion, a first cover member
and a second cover member, wherein each of said spine portion, said first cover member
and said second cover member includes a respective lower edge, characterized in that
when said spine portion and said first cover member occupy a same plane, the lower
edge of said spine portion and the lower edge of said first cover member subtend an
angle of less than 180°.
[0009] Embodiments of the present invention will now be described, by way of examples only,
with reference to the accompanying drawings, in which:
Fig. 1 is a front perspective view of a cover for a paper-retaining device according
to the present invention, in a closed configuration;
Fig. 2 is a rear perspective view of the cover shown in Fig. 1;
Fig. 3 is a front perspective view of the a paper-retaining device according to an
embodiment of the present invention, incorporating the cover shown in Fig. 1 with
the interior components shown in dotted lines;
Fig. 4 is a rear perspective view of the device shown in Fig. 3 with the interior
components shown in dotted lines;
Fig. 5 is a further front perspective view of the device shown in Fig. 3 with the
interior components shown in dotted lines, in which a number of pieces of paper are
retained by the device;
Fig. 6 is a further rear perspective view of the device shown in Fig. 3 with the interior
components shown in dotted lines, in which a number of pieces of paper are retained
by the device;
Fig. 7 is a back view of the a paper-retaining device according to a further embodiment
of the present invention in a partly-opened configuration;
Fig. 8 is a left side view of the device shown in Fig. 7;
Fig. 9 is a front view of the device shown in Fig. 7;
Fig. 10 is a top view of the device shown in Fig. 7;
Fig. 11 is a front perspective view of the device shown in Fig. 7;
Fig. 12 is a rear perspective view of the device shown in Fig. 7;
Fig. 13 is an exploded view of the device shown in Fig. 7;
Fig. 14 is an assembled view of the device shown in Fig. 7, in an opened configuration;
Fig. 15 is a further perspective view of the device shown in Fig. 14 in an opened
configuration, in which a number of pieces of paper are retained by the device;
Fig. 16 is a top view of the device shown in Fig. 7, in a fully opened configuration,
in which a number of pieces of paper are retained by the device;
Fig. 17 is a front perspective view of a paper-retaining device according to a yet
further embodiment of the present invention, in a closed configuration, with the interior
components shown in dotted lines;
Fig. 18 is a rear perspective of the device shown in Fig. 17, with the interior components
shown in dotted lines;
Fig. 19 is a further front perspective view of the device shown in Fig. 17 with the
interior components shown in dotted lines, in which a number of pieces of paper are
retained by the device;
Fig. 20 is a further rear perspective view of the device shown in Fig. 17 with the
interior components shown in dotted lines, in which a number of pieces of paper are
retained by the device;
Fig. 21 is a rear view of a paper-retaining device according to a still further embodiment
of the present invention, in a partly-opened configuration;
Fig. 22 is a left side view of the device shown in Fig. 21;
Fig. 23 is a front view of the device shown in Fig. 21;
Fig. 24 is a top view of the device shown in Fig. 21;
Fig. 25 is a front perspective view of the device shown in Fig. 21, with the interior
components shown in dotted lines;
Fig. 26 is a bottom perspective view of the device shown in Fig. 25;
Fig. 27 is an exploded view of the device shown in Fig. 25;
Fig. 28 is an assembled view of the device shown in Fig. 27;
Fig. 29 is a perspective view of the device shown in Fig. 28 in an opened configuration,
in which a number of pieces of paper are retained by the device;
Fig. 30 is a top view of the device shown in Fig. 29;
Fig. 31 is a front perspective view of a paper-retaining device according to an additional
embodiment of the present invention, in a closed configuration, with the interior
components shown in dotted lines;
Fig. 32 is a further front perspective view of the device shown in Fig. 31, in a partly
opened configuration;
Fig. 33 is a further perspective view of the device shown in Fig. 33;
Fig. 34 is a front perspective view of a paper-retaining device according to a still
further embodiment of the present invention, in a closed configuration, with the interior
components shown in dotted lines;
Figs. 35 and 36 are perspective views of the device shown in Fig. 34, in a partly
opened configuration;
Fig. 37 is a front perspective view of a paper-retaining device according to a yet
further embodiment of the present invention, in a closed configuration, with the interior
components shown in dotted lines;
Figs. 38 and 39 are perspective views of the device shown in Fig. 37, in a partly
opened configuration;
Fig. 40 is a front perspective view of a paper-retaining device according to a further
embodiment of the present invention, in a closed configuration, with the interior
components shown in dotted lines;
Figs. 41 and 42 are perspective views of the device shown in Fig. 40, in a partly
opened configuration;
Fig. 43 is a front perspective view of a paper-retaining device according to a yet
additional embodiment of the present invention, in a closed configuration, with the
interior components shown in dotted lines;
Figs. 44 and 45 are perspective views of the device shown in Fig. 43, in a partly
opened configuration;
Fig. 46 is a front perspective view of a paper-retaining device according to a still
further embodiment of the present invention, in a closed configuration, with the interior
components shown in dotted lines;
Fig. 47 is a top view of the device shown in Fig. 46, in a fully-opened configuration;
Fig. 48 is a rear view of the device shown in Fig. 46;
Fig. 49 is a left side view of the device shown in Fig. 48;
Fig. 50 is a front view of the device shown in Fig. 48; and
Fig. 51 is a top view of the device shown in Fig. 49.
[0010] Figs. 1 and 2 show, respectively, a front perspective view and a rear perspective
view of a cover, generally designated as 100, for a paper-retaining device, e.g. a
ring-binder folder or lever-arch type file, according to an embodiment of the present
invention.
[0011] The cover may be 100 may be made of plastics, leather, imitations of leather, cloth
material, or cardboard, and includes a planar front cover 102, a planar rear cover
104 and a planar spine 106. The front cover 102 has a straight lower edge 102a, the
rear cover 104 has a straight lower edge 104a, and the spine 106 also has a straight
lower edge 106a. The front cover 102 is pivotably engaged with and pivotably movable
relative to the spine 106 about a straight edge 108; and the rear cover 104 is pivotably
engaged with and pivotably movable relative to the spine 106 about a straight edge
110.
[0012] The angle α between the lower edge 102a of the front cover 102 and the edge 108 between
the front cover 102 and the spine 106 is less than 90°. The angle β between the lower
edge 104a of the rear cover 104 and the edge 110 between the rear cover 104 and the
spine 106 is also less than 90°. The angles α and β are preferably the same.
[0013] Figs. 3 and 4 show, respectively, a front perspective view and a rear perspective
view of a lever-arch type file according to an embodiment of the present invention,
generally designated as 200. The file 200 includes the cover 100 and a lever-arch
type file mechanism 202 (shown in dotted lines) fixedly secured, e.g. by a number
of rivets or screws, to the rear cover 104. It can be seen from Figs. 5 and 6 that
the lever-arch type file mechanism 202 in the file 200 can releasably retain pieces
of hole-punched paper, in the conventional manner.
[0014] A further embodiment of a paper-retaining device according to the present invention
is shown in Figs. 7 to 16, and generally designated as 300. The device 300 also includes
a cover 301 (which may be made of plastics, leather, imitations of leather, cloth
material or cardboard) with a front cover 302 hingedly engaged with an pivotable relative
to a spine 306 about a straight edge 308, and the spine 306 is also hingedly engaged
with an pivotable relative to a rear cover 304 about a straight edge 310. A lever-arch
type file mechanism 312 is fixedly secured, to an inner surface 304b of the rear cover
304, for releasably retaining pieces of paper.
[0015] It can be seen in Figs. 7 and 9 that the angle α between the lower edge 302a of the
front cover 302 and the edge 308 between the front cover 302 and the spine 306 is
less than 90°. The angle β between the lower edge 304a of the rear cover 304 and the
edge 310 between the rear cover 304 and the spine 306 is also less than 90°. The angles
α and β are preferably the same.
[0016] Figs. 7 to 9 also clearly show that the cover 301 includes a circular aperture 314
adjacent a lower end of the spine 306 allowing insertion of one or more fingers of
a user, for moving (e.g. pulling) the device 300. Two elongate apertures 316 are also
formed on the front cover 302, each allowing insertion of part of a respective ring
of the lever-arch type file mechanism 312 when the device 300 is in the closed configuration.
[0017] Figs. 11 and 12 show the paper-retaining device 300 in an upstanding position. It
can be seen in Figs. 13 and 14 that the lever-arch type file mechanism 312 is fixedly
secured by several rivets 318 onto the inner surface 304b of the rear cover 304 to
form the paper-retaining device 300, for releasably retaining pieces of paper, as
shown in Fig. 15.
[0018] Fig. 16 shows several significant angles and dimensions of the paper-retaining device
300. Firstly, as distinct from conventional arrangements, when the front cover 302,
the rear cover 304 and the spine 306 are co-planar with one another, the obtuse angle
γ between the lower edge 304a of the rear cover 304 and the lower edge 306a of the
spine 306 is less than 180°, and so is the obtuse angle δ between the lower edge 302a
of the front cover 302 and the lower edge 306a of the spine 306. The angles γ and
δ are preferably the same. As the edges 308, 310 are both perpendicular to the lower
edge 306a of the spine 306, it follows that γ = 90° + β, and δ = 90° + α.
[0019] In addition, a longitudinal axis L-L of the lever-arch type file mechanism 312 is
perpendicular to the lower edge 304a of the rear cover 304 to which it is fixedly
engaged. The longitudinal axis L-L of the lever-arch type file mechanism 312 is thus
inclined relative to the edge 310 at an acute angle φ, which is equal to 180° - γ.
[0020] For an A4 size device (i.e. a device 300 suitable for retaining A4 size paper):
- 212 mm ≤ P ≤ 318 mm, and preferably P=275mm;
- 274 mm ≤ H ≤ 351 mm, and preferably H=305mm;
- 212 mm ≤ W ≤ 418 mm, and preferably W=305mm;
- 24 mm ≤ D ≤ 85 mm, and preferably D=55mm, 75mm or 85mm;
- α = β;
- 69.95° ≤ α < 90°;
- γ = δ;
- 159.95° ≤ γ < 180°; and
- 0° < φ ≤ 20.05°
[0021] For an F4 size device (i.e. a device 300 suitable for retaining F4 size paper):
- 225 mm ≤ P ≤ 319 mm;
- 311 mm ≤ H ≤ 391 mm;
- 225 mm ≤ W ≤ 419 mm;
- 36 mm ≤ D ≤ 87 mm;
- α = β;
- 72.18° ≤ α < 90°;
- γ = δ;
- 162.18° ≤ γ < 180°; and
- 0° < φ ≤ 17.82°
[0022] For an B5 size device (i.e. a device 300 suitable for retaining B5 size paper):
- 189 mm ≤ P ≤ 295 mm;
- 240 mm ≤ H ≤ 325 mm;
- 189 mm ≤ W ≤ 395 mm;
- 19 mm ≤ D ≤ 48 mm;
- α = β;
- 67.38° ≤ α < 90°;
- γ = δ;
- 157.38° ≤ γ < 180°; and
- 0° < φ ≤ 22.62°
[0023] It can be seen that, with such an arrangement, when pieces of paper 320 are retained
by the mechanism 312 of the device 300, the top right hand corner of the paper 320
is tilted upwardly by the angle φ, thus facilitating the writing movement of a right-handed
user. It is also not necessary to adjust the device 300 such that its lower left hand
corner of the front cover 302 points towards the user and extends beyond an edge of
the table on which it is placed, causing discomfort and possible danger to the user.
[0024] A further embodiment of a paper-retaining device according to the present invention
is shown in Figs. 17 to 20, generally designated as 400, and incorporating the cover
100 discussed above.
[0025] To an inner surface 404b of a rear cover 404 of the device 400 is fixedly secured
a ring-binder mechanism 412 for retaining pieces of paper. A longitudinal axis M-M
of the ring-binder mechanism 412 is inclined relative to an edge 410 between the rear
cover 404 and an adjoining spine 406 by an acute angle. The axis M-M is perpendicular
to the lower edge 404a of the rear cover 404, as shown in Fig. 18.
[0026] A paper-retaining device according to a yet further embodiment of the present invention
is shown in Figs. 21 to 30, generally designated as 500. This device 500 is similar
to the device 400 shown in Figs. 17 to 20 and discussed above, with the main difference
being that the device 500 has a circular aperture 514 on a spine 506 of a cover 501
of the device 500.
[0027] It can be seen in Figs. 27 that a ring-binder mechanism 512 is fixedly secured to
an inner surface 504b of a rear cover 504 of the cover 501 to form the paper-retaining
device 500.
[0028] As distinct from conventional arrangements, when a front cover 502, the rear cover
504 and the spine 506 occupy a same plane, the obtuse angle γ between a lower edge
504a of the rear cover 504 and a lower edge 506a of the spine 506 is less than 180°,
and so is the obtuse angle δ between a lower edge 502a of the front cover 502 and
the lower edge 506a of the spine 506. The angles γ and δ are preferably the same.
In addition, a longitudinal axis S-S of the ring-binder mechanism 512 is perpendicular
to the lower edge 504a of the rear cover 504 to which it is fixedly engaged. The longitudinal
axis S-S of the ring-binder mechanism 512 is thus inclined relative to an edge 510
adjoining the spine 506 and the rear cover 504 at an acute angle φ, which is equal
to 180° - γ.
[0029] Figs. 31 to 33 show various views of a paper-retaining device according to a still
further embodiment of the present invention, generally designated as 600. This device
600 is structurally similar to the device 200 shown in Figs. 3 to 6 and discussed
above. The main difference between this device 600 and the device 200 is that, in
the device 200, the two free corners of the rear cover 104 and the two free corners
of the front cover 102 are rounded off; whereas in the device 600, the corresponding
corners are not rounded-off.
[0030] A paper-retaining device according to an additional embodiment of the present invention
is shown in Figs. 34 to 36, and generally designated as 700. This device 700 is structurally
similar to the device 200 shown in Figs. 3 to 6 and discussed above. A special feature
residing in the device 700 is that a semi-circular recess 720 is formed along an upper
edge 706b of a spine 706 of the device 700, and a semi-circular recess 722 is formed
along a lower edge 706a of the spine 706. These two recesses 720, 722 are sized for
allowing insertion of a respective finger of a user, for pulling the device 700, for
example, out from a row of devices 700 standing one next to the other.
[0031] A paper-retaining device according to an additional embodiment of the present invention
is shown in Figs. 37 to 39, and generally designated as 800. This device 800 is also
structurally similar to the device 200 shown in Figs. 3 to 6 and discussed above.
A special feature residing in the device 800 is the provision of two apertures 820,
822, in which the aperture 820 is formed through an edge 808 adjoining a front cover
802 and a spine 806 of the device 800; and the aperture 822 is formed through an edge
810 adjoining a rear cover 804 and the spine 806 of the device 800. These two recesses
820, 822 are sized and configured for allowing insertion of a respective finger of
a user, for pulling the device 800, for example, out from a row of devices 800 standing
one next to the other.
[0032] A paper-retaining device according to a yet further embodiment of the present invention
is shown in Figs. 40 to 42, and generally designated as 900. This device 900 is structurally
similar to the device 800 shown in Figs. 37 to 39 and discussed above. A special feature
of the device 900 over the device 800 is that the device 900 has three pairs of apertures
920a, 922a, 920b, 922b, 920c, 922c arranged one above another, which collectively
allow insertion of more than two fingers of a user, to facilitate removal of the device
900 from a row of paper-retaining devices.
[0033] A paper-retaining device according to another further embodiment of the present invention
is shown in Figs. 43 to 45, and generally designated as 1000. This device 1000 is
structurally similar to the device 200 shown in Figs. 3 to 6 and discussed above.
A special feature of the device 1000 over the device 200 is that each of a front cover
1002 and a rear cover 1004 of the device 1000 is formed with an undulating portion,
forming a series of parallel recesses 1006. A user may thus grip the device 1000 by
holding the recesses 1006, thus facilitating holding of the device 1000.
[0034] A paper-retaining device according to a still further embodiment of the present invention
is shown in Figs. 46 to 51, and generally designated as 1100. The device 1100 can
be said to be a combination of the device 700 shown in Fig. 34 and the device 900
shown in Fig. 40, in that it includes a semi-circular recess 1108 at an upper end
of a spine 1106, a semi-circular recess 1110 at a lower end of the spine 1106, and
three pairs of apertures 1112a, 1114a, 1112b, 1114b, 1112c, 1114c through edges 1116,
1118 adjoining a rear cover 1104 and the spine 1106, and a front cover 1102 and the
spine 1106 respectively.
[0035] It should be understood that the above only illustrates examples whereby the present
invention may be carried out, and that various modifications and/or alterations may
be made thereto without departing from the spirit of the invention.
[0036] It should also be understood that certain features of the invention, which are, for
clarity, described in the context of separate embodiments, may be provided in combination
in a single embodiment. Conversely, various features of the invention which are, for
brevity, described in the context of a single embodiment, may also be provided separately
or in any appropriate sub-combinations.
1. A substrate for a paper-retaining device, including a spine portion, a first cover
member and a second cover member,
wherein each of said spine portion, said first cover member and said second cover
member includes a respective lower edge,
wherein said first cover member is pivotably engaged with and movable relative to
said spine portion about a first edge, and
wherein said second cover member is pivotably engaged with and movable relative to
said spine portion about a second edge,
characterized in that an angle subtended between said lower edge of said first cover member and said first
edge is less than 90°.
2. A substrate according to Claim 1 further characterized in that an angle subtended between said lower edge of said second cover member and said second
edge is less than 90°.
3. A substrate according to Claim 2 further characterized in that said angle is equal to or larger than 67.38°.
4. A substrate according to Claim 2 or 3 further characterized in that the angle subtended between said lower edge of said first cover member and said first
edge is substantially identical to the angle subtended between said lower edge of
said second cover member and said second edge.
5. A substrate according to any of the preceding claims further characterized in that when said first and second cover members are substantially perpendicular to said
spine portion, said lower edge of said first cover member is substantially parallel
to said lower edge of said second cover member.
6. A substrate according to any of the preceding claims further characterized in that a first recess is formed on said lower edge of said spine portion.
7. A substrate according to Claim 6 further characterized in that said first recess is generally semi-circular in shape.
8. A substrate according to any of the preceding claims further characterized in that a second recess is formed on an upper edge of said spine portion.
9. A substrate according to Claim 8 further characterized in that said second recess is generally semi-circular in shape.
10. A substrate according to any of the preceding claims further characterized in that said first cover member is generally trapezoidal in shape.
11. A substrate according to any of the preceding claims further characterized in that said second cover member is generally trapezoidal in shape.
12. A substrate according to any of the preceding claims further characterized in that an aperture is formed through each of said first and second edges.
13. A substrate according to Claim 12 further characterized in that each said aperture is sized and configured to receive a finger of a user.
14. A substrate according to Claim 12 or 13 further characterized in that said apertures are of substantially the same distance from said lower edge of said
spine portion.
15. A substrate according to any one of Claims 12 to 14 further characterized in that a plurality of apertures are formed through each of said first and second edges.
16. A substrate according to any of the preceding claims further characterized in that at least a recess is formed on each outer surface of said first and second cover
members.
17. A substrate according to Claim 16 further characterized in that a plurality of recesses are formed on each outer surface of said first and second
cover members.
18. A paper-retaining device including a substrate according to any of the preceding claims
fixedly engaged with means for releasably retaining at least a piece of paper.
19. A device according to Claim 18 further characterized in that a longitudinal axis of said retaining means is inclined relative to said first edge.
20. A device according to Claim 18 or 19 further characterized in that a longitudinal axis of said retaining means is inclined relative to said second edge.
21. A device according to Claim 18, 19 or 20 further characterized in that a longitudinal axis of said retaining means is substantially perpendicular to a lower
edge of said first cover member.
22. A substrate for a paper-retaining device, including a spine portion, a first cover
member and a second cover member,
wherein each of said spine portion, said first cover member and said second cover
member includes a respective lower edge,
characterized in that when said spine portion and said first cover member occupy a same plane, the lower
edge of said spine portion and the lower edge of said first cover member subtend an
angle of less than 180°.
23. A substrate according to Claim 22 further characterized in that said angle is equal to or larger than 157.38°.
24. A substrate according to Claim 22 or 23 further characterized in that when said spine portion and said second cover member occupy a same plane, the lower
edge of said spine portion and the lower edge of said second cover member subtend
an angle of less than 180°.
25. A substrate according to Claim 23 or 24 further characterized in that when said first and second cover members are substantially perpendicular to said
spine portion, said lower edge of said first cover member is substantially parallel
to said lower edge of said second cover member.
26. A substrate according to any one of Claims 22 to 25 further characterized in that a first recess is formed on said lower edge of said spine portion.
27. A substrate according to Claim 26 further characterized in that said first recess is generally semi-circular in shape.
28. A substrate according to any one of Claims 22 to 27 further characterized in that a second recess is formed on an upper edge of said spine portion.
29. A substrate according to Claim 28 further characterized in that said second recess is generally semi-circular in shape.
30. A substrate according to any one of Claims 22 to 29 further characterized in that said first cover member is generally trapezoidal in shape.
31. A substrate according to any one of Claims 22 to 30 further characterized in that said second cover member is generally trapezoidal in shape.
32. A substrate according to any one of Claims 22 to 31 further characterized in that an aperture is formed through each of said first and second edges.
33. A substrate according to Claim 32 further characterized in that each said aperture is sized and configured to receive a finger of a user.
34. A substrate according to Claim 32 or 33 further characterized in that said apertures are of substantially the same distance from said lower edge of said
spine portion.
35. A substrate according to any one of Claims 32 to 34 further characterized in that a plurality of apertures are formed through each of said first and second edges.
36. A substrate according to any one of Claims 22 to 35 further characterized in that at least a recess is formed on each outer surface of said first and second cover
members.
37. A substrate according to Claim 36 further characterized in that a plurality of recesses are formed on each outer surface of said first and second
cover members.
38. A paper-retaining device including a substrate according to any of Claims 22 to 37
fixedly engaged with means for releasably retaining at least a piece of paper.
39. A device according to Claim 38 further characterized in that a longitudinal axis of said retaining means is inclined relative to said first edge.
40. A device according to Claim 38 or 39 further characterized in that a longitudinal axis of said retaining means is inclined relative to said second edge.
41. A device according to Claim 38, 39 or 40 further characterized in that a longitudinal axis of said retaining means is substantially perpendicular to a lower
edge of said first cover member.