Note: Descriptions are shown in the official language in which they were submitted.
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STAPLER
Field of the Invention
The present invention relates to a stapler.
Background of the Invention
"Power-assisted" staplers are known, which provide a strong staple driving
force from a smaller user input force made to the stapler. Typically, "power-
assisted"
staplers use a power spring which stores energy as a result of a handle of the
stapler
being actuated by a user. The stored energy is then released to drive staples
from the
stapler. Patent publication US 6 145 728 applies the so-called "tucker"
construction to a
stapler. Staples are ejected from the stapler with a strong force by means of
the stapler
mechanism, which involves the simultaneous lifting of a plunger by a pivoting
lever and
compression of a power spring. After the plunger has been lifted a certain
distance, the
pivoting lever arm slips out of engagement with the plunger, which then
descends
rapidly under the action of the power spring so as to eject a staple from the
stapler. The
mechanism is not always reliable, however, and there is a risk that staples
might be
forced out of the stapler unexpectedly if the lever disengages from the
plunger
prematurely. Although attempts have been made to improve on the design to
avoid this
risk, these have resulted in coniplicated stapler structures. Furthermore, the
points of
the plunger which receive the lever can suffer from wear, owing to the large
amounts of
friction which are created when the lever slips out of engagement with the
plunger.
A different problem encountered with typical "desk-top" staplers is that to
replace staples, a user must turn and open the base and frame of the stapler
over a wide
angle, which is a cumbersome operation.
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Statement of the Invention
According to the present invention, there is provided a stapler coinprising:
(a) an actuator for application of a force to the stapler by a user;
(b) a staple ejector, movable from a first position to a second position to
eject a staple from the stapler;
(c) an energy storing element, arranged to store energy as force is applied to
the stapler via the actuator, and to release said energy by moving the staple
ejector from
the first position to the second position; and
(d) a resistive element, movable between a first condition in which it
maintains the staple ejector in the first position as the force is applied via
the actuator,
and a second condition in which it peniiits the staple ejector to move to the
second
position under the action of the energy storing element.
Embodiments of staplers according to the present invention may provide a
reliably actuated staple driving power, as the staple ejector is held in place
in the first
position until the resistive element moves into the second condition.
Embodiments may
be made of a small number of parts and be of simple construction. In
particular, the
resistive element used to block movement of the staple ejector during a
stapling
operation may be a siniple structure. Hence, the manufacturing of embodiments
of the
present invention may be simplified and the associated costs reduced, in
addition to the
reliability of the stapler being increased.
In one embodiment, a stapler has a handle, a hammer for ejecting staples, and
a
hammer spring for driving the hammer when released. The hammer is prevented
from
descending by a link member, which is held in place by a spring. As the handle
is
depressed, the hammer spring is compressed until a trigger is brought into
contact with
the link member, releasing the hammer spring to drive the hammer and thus
release a
staple. Hence, a large stapling force may be applied accurately and reliably.
Brief Description of the Drawings
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There now follows, by way of example only, a detailed description of preferred
embodiments of the present invention in wliich:
Figure 1 is an external side elevation view of a first embodiment of a stapler
according to the present invention, at rest;
Figure 2 is an external view of the stapler of Figure 1 during a stapling
operation;
Figure 3 is a cross-sectional view of the stapler of Figure 1 in an "at rest"
condition;
Figure 4 is an exploded perspective view of part of the stapler of Figure 1;
Figure 5 is a top view of a hammer of the stapler of Figure 1;
Figure 6 is a side view showing parts of the stapler of Figure 1 in more
detail;
Figure 7 is a front view of a link member of the stapler of Figure 1;
Figure 8 is a cross-sectional top view of the inner structure of the stapler
of
Figure 1;
Figure 9 is a cross-section though the inner structure of the stapler of
Figure 1;
Figures 10 to 14 are cross-sectional views showing the inner structure of the
stapler of Figure 1 during a stapling operation;
Figure 15 shows the stapler of Figure 1 with a magazine of the stapler
extended
from the stapler;
Figure 16 is a cross-sectional view showing the inner structure of a stapler
according to a second embodiment of the present invention at rest, omitting
views of a
link spring and hammer spring for clarity; and
Figure 17 is a cross-sectional view showing the stapler of Figure 16 during a
stapling operation.
Detailed Description of the Embodiments
A first embodiment of a stapler according to the present invention will now be
described with reference to Figures 1 to 15.
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Figures 1 and 2 illustrate the first enibodiment at rest and in use,
respectively.
As shown in Figure 1, the first embodiment of a stapler 1 comprises a base 2,
frame 3
and handle 10. The frame 3 and base 2 are connected by means of a frame base
shaft 59,
such that the frame 3 may pivot relative to the base 2. Similarly, the handle
10 is
pivotally mounted to the frame 3 by means of a frame handle shaft 60. An upper
face of
the base 2 is provided with a plate-like anvil 61, and the frame 3 is provided
with a
magazine 55 which can be loaded with staples.
Items to be stapled together, such as loose sheets of paper, are inserted into
the
gap between the anvil 61 and the magazine 55 at the front of the stapler 1,
and the
handle 10 is pushed downwardly by a user towards the base 2, as illustrated in
Figure 2.
As will be described in greater detail hereinafter, this results in a staple
being pushed
out from the magazine 55 with a strong ejection force by the mechanism of the
stapler.
Legs of the ejected staple pierce the loose items being stapled, and
subsequently tips of
the staple legs contact the anvil 61. The upper surface of the anvil 61 is
provided with a
contoured scoop (not shown) such that the legs contacting the scoop are bent
towards
each other, thus closing the staple and fastening the loose items together.
The anvil 61
is also provided with a contoured scoop pair (not shown), which cause the
staple legs to
be moved apart, rather than together, to secure the loose items. Whether the
staple legs
are brought into contact with the contoured scoop or the contoured scoop pair
is
determined by the user, who may rotate the anvi161 relative to the base 2 to
position the
scoop or scooped pair appropriately. Once the loose items have been stapled
together,
the handle 10 is released by the user to retun7 to the "at rest" condition
shown in Figure
1, as described in greater detail later.
The inner structure of the stapler 1 will now be described with reference to
Figures 3 to 9. As indicated above, the handle 10 is pivotally mounted to the
frame 3 by
means of a frame handle shaft 60. The handle 10 itself comprises two
downwardly-
depending sidewalls 62 linked by a joining wall 63, which is angled upwardly
relative
to the base 2. As seen from Figure 3, the internal surface of the joining wall
63 is
provided with a downwardly-depending trigger 12, the purpose of which will
become
clear ftirther on, and a hammer spring holder 13, in the form of a rounded
protnision.
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A handle spring 50 is connected to the frame 3 by means of a shaft 51. The
handle spring 50 comprises an upper arm 64 and a lower ann 65 which extend
from
opposed ends of a coil 66 of the hammer spring 50. The lower arm 64 contacts
an
abutment on the frame 3. The upper arm 64 contacts the internal surface of the
joining
wal163, and biases the handle 10 upwardly, away from the base 3.
A lower portion of the frame 3 is provided with an elongate magazine 55 for
staples. The magazine 55 is slidably mounted on the fraine 3, and the front
end of the
magazine 55 has an opening 66 from which staples may be ejected.
The frame 3 is also provided with a hammer 9, which is located on the frame 3
above and towards the front of the magazine 55. The hammer 9 is pivotally
mounted to
the frame 3 by means of a hammer frame pin 25, as described in greater detail
below.
The haniuner 9 itself is shown in more detail in Figures 4 and 5. The hammer
coniprises a franie formed of two substantially "L"-shaped side walls 67,
which are
joined together by a horizontal bottom wall 4 and a vertical end wall 68
provided at the
froiit of the hammer 9. Each of the side walls 67 is provided with a pair of
holes 7, 8;
each hole of each side wall 67 is positioned so as to be in alignment with the
corresponding hole formed in the other side wall. Each side wall 67 is also
provided
with a hammer spring stopper 6 in the form of a horizontal plate, disposed at
the top of
each side wall 67 at the rear of the hammer 9. At the front of the hammer 9, a
blade
mounting protrusion 5 projects forwardly from the vertical end wall 68. The
cross-
section of this protrusion 5 is such that a blade 45 may be mounted on the
protnision 5,
by inserting the protrusion 5 through a correspondingly-shaped hole 69 fonned
in the
blade. As will become clear, the hammer 9 and the blade 45 comprise a staple
ejector
for ejecting staples from the magazine 55.
As shown in Figure 5, the bottom wall 4 of the hammer 9 is provided with a
central rectangular opening 16. The width of this opening 16 is narrowed
towards the
front of the hammer 9 by link stopper portions 15 fonned on the bottom wal14.
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As shown in Figure 3, the hammer 9 is pivotally mounted to the fi=ame 3 by
means of a hanuner franie pin 25, which protrudes through the aligned rear-
most holes 8
of the hammer side walls 67 and projects into receiving portions (not shown)
formed in
the frame 3. The hammer frame pin 25 also protrudes through, and thus provides
a
mounting for, the coil 70 of a hanuner spring 20, which is located in the
region between
the hammer side walls 67 at the rear end of the hammer 9. The hammer spring 20
comprises an upper ann 21 and a lower arm 22, which extend from opposed ends
of the
hammer spring coil 70. The extent of upward movement of the upper arm 21 is
restricted by the hammer spring stopper 6 of the adjacent hainmer side wall
67. The
lower ann 22 of the hammer spring 20 lies on the bottom wall 4 of the hammer.
When
the hammer 9 is mounted to the frame 3, as shown in Figure 3, an upper side of
the
upper arm 21 contacts the hammer spring holder 13, formed on the inner face of
the
handle 10. In this "at rest" condition, the angle between the upper and lower
arms of the
hammer spring 20 is a .
Also comiected to the hammer 9 is a link meniber 30, which protrudes through
the opening 16 formed in the bottom wall 4 of the hammer 9. As illustrated in
Figure 4,
the link member 30 comprises an upper member 31 and a pair of lower menibers
32.
The upper member 31 is in the form of a plate having a trigger receiving
portion 36
protruding forwardly of the upper member 31 at its lower end. The upper member
31 is
pivotally connected, at its lower end, to each of the plate-like lower members
32 by a
connection pin 33.
The link member 30 is pivotally mounted to the hammer 9 by mounting pins
34, which project from either side of the upper end of the upper member 31 and
protrude through the foremost aligned holes 7 of the hammer side walls 67.
Similarly,
the lower members 32 are pivotally mounted to the frame 3 by means of
mouriting pins
35, which project outwardly from lower ends of the lower members 32 and are
received
in holes (not shown) formed in the frame 3. Thus, it is to be understood that
the link
member 30 is connected between the hammer 9 and the frame 3.
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A link spring 40 is mounted to the fraine by means of a shaft 41. The link
spring 40 comprises a lower arm 71 and an upper arm 72 extending from opposed
ends
of a link spring coil 73. The lower arm 71 contacts an abutment provided on
the frame
3, and the upper arm 72 of the liiik spring 40 contacts an upper portion of a
rear face of
one of the lower members 32 of the link member 30. The link spring 40 thus
provides a
bias which acts to push the link member 30, and in particular the connection
pin 33, in a
forward direction, i.e. in a direction towards the front of the stapler 1. As
a result of this
bias, front faces 37 of the lower members 32 are brought into contact with the
link
stopper portions 15 formed on the bottom wall 4 of the hammer 9 when the
stapler 1 is
at rest, as illustrated in Figure 6. Thus, when the stapler 1 is at rest, the
link member 30
is maintained in an upright position, with the axes of the connection pin 33
and
mounting pins 34, 35 lying substantially in the same plane.
The operation of the first embodiment will now be explained, with reference to
Figures 9 to 14. Figure 9 shows the frame 3, magazine 55 and hammer 9 of the
stapler 1
when the stapler 1 is at rest. To staple items, a user presses down on the
handle 10,
which results in the handle spring 50 being compressed and the frame 3
rotating
downwardly about the frame base shaft 59, such that the items to be stapled
become
trapped between the anvil 61 of the base 2 and the forward end of the magazine
55. In
addition to compression of the handle spring 50, the hammer spring 20 is also
increasingly compressed by downward movement of the hatidle 10. The upper ami
of
the hammer spring 20 is prevented from moving upwards to release this
compression
owing to its contact with the hammer spring holder 13. The lower arm 22 of the
hammer spring therefore applies a generally downwardly-directed force,
substantially
parallel to the plane in which the axes of the connection pin 33 and mounting
pins 34,
lie, to the bottom wall 4 of the hammer 9. Despite the application of this
force to the
hammer, however, the han7mer 9 is prevented from moving downwardly towards the
base and frame 3 by the upright link member 30, which is connected between the
hammer and the frame. The link member is maintained in its upright position by
the
30 link spring 40 and link stopper portions 15 of the hammer 9, which resist
lateral
movement of the connection pin 33.
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As the handle 10 is pushed further towards the base 2, the hammer spring 20 is
compressed further, such that an increasing downward force is applied to the
hammer 9,
which is opposed by the upright link member 30. Eventually, at a predetermined
position of the handle 10, the trigger 12 is brought into contact with the
trigger
receiving portion 36 of the upper member of the link member 30, as shown in
Figure
10. At that point, only a minimal amount of additional downward force on the
handle
10, moving the handle beyond the predetermined position, is required to push
the
connection pin 33 rearward, out of the plane in which the mounting pins 34, 35
lie,
against the bias of the link spring 40. When this occurs, the link member 30
can no
longer sustain the downward force being applied on the hanuner 9 by the hammer
spring 20, and the link member 30 collapses into a reversed L-shape as the
front of the
hammer 9 rapidly descends under the action of the compressed hammer spring 20.
As
may be seen from Figures 11 and 12, which show sequential stages in the
stapling
process, the rapid descent of the hammer 9 causes the blade 45 installed on
the front of
the haminer 9 to forcibly eject a staple from the opening 66 at the front of
the magazine
55. The ejected staple then pierces and fastens together the items to be
stapled, as
described with reference to Figure 2 above.
Thus, moving the handle 10 downwardly causes continued compression of the
hammer spring 20, until a trigger point is reached at which the trigger 12
contacts the
trigger receiving portion 36 of the link member 30. A small further downward
niovement of the handle 10 then results in rearward movement of the comlection
pin 33.
This, in turn, results in the simultaneous descent of the hammer 9, under the
action of
the coinpressed hammer spring 20, and collapse of the link member 30, and
subsequent
staple ejection.
As the trigger 12 contacts the trigger receiving portion 36 when the handle 10
is in a predetemiined position, it is thus to be understood that the amount of
energy
stored in the hammer spring 29 at the time that the hammer 9 is released may
also be
predetermined, as the hammer spring will have undergone a given amount of
compression once the trigger point is reached. Thus, staples will be reliably
ejected
from the stapler 1 with the same stapling force.
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When the items have been stapled, the user simply removes their hand from the
handle 10 to release the downward force on the stapler. The handle 10 then
moves
upwardly, away from the base 2, under the action of the compressed handle
spring 50.
As the handle moves upwardly, the upper arm 21 of the hammer spring 20 moves
upwardly also, and in so doing reaches the position shown in Figure 13. In the
position
of Figure 13, the upper arm 21 of the hammer spring 20 contacts an adjacent
hammer
spring stopper 6, and the angle subsumed by the upper arm 21 and lower arni 22
of the
hammer spring 20 is again a . This angle of separation is maintained until the
handle 10
returns to its pre-stapling position, indicated "A" in Figure 14.
As indicated in Figure 13, the liiik spring 40 applies a continual forward
bias to
the link member 30. This causes the link stopper portions 15 to ride up the
inclined
front faces of the lower members 32 of the link member 30, resulting in the
simultaneous raising of the hammer 9 and alignment into the same vertical
plane of the
axes of the connection pin 33 and mounting pins 34, 35, until. the hammer 9
and link
member 30 are restored to the configuration illustrated in Figure 3. It will
be
appreciated, therefore, that the stapler 1 simply and automatically reverts to
its "at rest"
condition once downward pressure is removed from the handle 10.
As shown in Figure 15, the sliding mounting of the magazine 55 enables the
magazine 55 to be pulled forwardly of the frame 3 to replace ejected staples.
This
functionality is enabled by the fact that the stapler 1 uses a resistive
element, in the form
of a link member 30, to block the descent of the hammer 9 and blade 45 until
the block
is released, rather than using a blade 45 mounted on the front of the magazine
55. Thus,
the -magazine 55 can be pulled forwardly to exchange staples, meaning that the
replacement of staples is simple and convenient, and does not require relative
rotation of
the base and frame.
Figures 16 and 17 show a second embodiment of the invention, wherein the
sanie staple ejection mechanism as described above with reference to the first
embodiment is applied to a more compact stapler. As the configuration of the
stapler
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mechanism is the saine, like parts are indicated by like numerals and further
description
thereof is not given here.
The embodiments described above are illustrative of rather than limiting to
the
present invention. Alternative embodiments apparent on reading the above
description
may nevertheless fall within the scope of the invention.
