Staple supply indicator

A stapler for attaching a plurality of sheets of paper, or the like, to each other comprises an elongated anvil member, forming a base, an elongated staple magazine member and an elongated driver member, forming a cover, all pivotally connected, at one end, to each other, there being a detent on the magazine member, a longitudinally slidable latch on the cover member lockable under the detent and the usual longitudinally movable, spring urged staple follower. The staple follower moves the latch to release position, near the end of its path, to indicate that the supply of staples is nearly exhausted.

BACKGROUND OF THE INVENTION 
The present invention relates to an improvement in staplers for commercial 
and residential use. More specifically, the stapler of the present 
invention will enable the user to physically be alerted when the stapler 
is empty and needs refilling. 
One of the disadvantages and drawbacks of the standard stapler involves 
determining when the stapler is empty before the staples actually run out. 
During a large stapling job, the user is oftentimes surprised to discover 
that the stapler needs loading. Usually, this becomes evident after 
several papers have been stapled unsuccessfully. It has long been 
desirable to remedy this situation and provide a warning to the user that 
the stapler is empty. There has been an attempt to solve this problem in 
the past as evidenced by a British stapler, discovered by the applicant, 
in which a small window is supplied in the side of the staple magazine in 
which the end staples may be viewed. However, the user must continually 
watch the side window lest the staples run out unnoticed. This constant 
inspection alleviates the problem of staples running out without warning, 
but creates considerable problems in the efficiency of operation and 
convenience for the operator. 
Another solution, proposed in the prior art, quite similar to the above is 
exemplified by U.S. Pat. No. 2,341,530 to Crosby of Feb. 15, 1944. The 
Crosby Patent shows a staple tacker which incorporates an indicator means 
to determine the exhaustion of staples within a magazine while the stapler 
is closed. This is also accomplished by the use of a small window or 
perforation in the side of the staple magazine. A red indicator or target 
is painted on the inner staple follower such that as the follower advances 
and one or more staples are left, the user will view the red indicator and 
realize that loading is necessary. Such a perforation is not only small, 
but relatively difficult to observe during the stapling process. Thus, the 
user must stop between each stapling action to determine whether the red 
indicator is showing. Constant monitoring of a side window would prove to 
be highly inefficient when stapling a series of multiple papers. 
Consequently, the user may choose to ignore an indicator of this type and 
simply wait for staples to be exhausted. 
Another solution, similar to the Crosby Patent is shown in U.S. Pat. No. 
2,973,519 to Jopp of Mar. 7, 1961. The Jopp invention is concerned with 
non-jamming staplers and provides a means for seeing when only a few 
staples remain. In this regard, apertures are provided in an apron 33 and 
in the staple magazine. Normally, the user sees the silver luster of the 
staples until diminishing staples cause the apertures to overlap whereby 
the user sees the black color of the magazine which will indicate that 
loading is required. Again, the apertures are so small and poorly located 
on the side that the user must take special care not to miss the warning. 
In the "Bostitch" type stapler, the driver member is urged upwardly from 
the magazine member when a longitudinally slidable latch on the driver 
member is slid rearwardly out from under a sidewise projecting detent on 
the magazine member and located in front of the latch. 
In this invention the Bostitch type stapler is provided with a similar 
detent but located in rear of the latch so that the latch releases by 
forward sliding on the magazine member. The conventional inverted U shaped 
staple follower has one of its legs further elongated and provided with an 
upstanding integral lug which strikes the latch to release it forwardly 
when the follower nears the end of its path. This not only releases the 
driver member from the magazine member to indicate exhaustion of staples, 
but the conventional leaf spring snaps the driver member upwardly to 
visually reveal the empty magazine. 
If the Bostitch Type Stapler still includes the rearward sliding latch 
release, a flexible strand may extend from the staple follower back around 
the pivot pin of the stapler and thence forwardly to the latch so that 
further advance of the follower at the end of its path will pull the latch 
rearwardly toward the pivot pin to snap up the driver member and indicate 
refill. 
The well known "Swingline" type stapler is constructed in a manner similar 
to the "Bostitch" stapler except that it has a coil spring connecting the 
staple follower to the driver member and the latch is a pin, movable in a 
slot in the driver member, the pin becoming latched in undercut in the 
magazine member, but released by longitudinal movement of the pin away 
from the pivot against spring tension. In this invention, when adapted to 
the "Swingline" construction, the staple follower also is provided with 
integral upstanding lug means which engages the movable pin latch to 
release it forwardly when the staple follower nears the end of its path, 
thereby releasing the driver member from the magazine member. 
In any stapler structure, a window may be provided in the upper forward 
portion of the driver member to reveal the staples in the magazine 
therebelow and visually indicate exhaustion from above, rather than from 
the side as in the prior art.

As shown in the drawings, 20 is a stapler of a well known type such as a 
"Bostitch", having an elongated anvil member 21, forming a base 22 to 
maintain the stapler in upright position, an anvil 23 in the forward 
portion 24 for bending in the ends of staples, and having a pair of 
laterally spaced upstanding walls 25 and 26 in the rearward portion 27. 
Stapler 20 includes an elongated staple magazine member 28 having a 
rearward portion 29, pivotally mounted on a pin 31 between the walls 25 
and 26 of the anvil member 21, and having a forward portion 32 wih a 
staple guideway 33 leading to the anvil 23. The intermediate portion 34 of 
member 28 is a magazine 35 for staples 36 pushed by staple follower 37 in 
turn pushed by coil spring 38 captive on rod 39. 
Stapler 20 also includes an elongated driver member 41, in the form of a 
cover overlying the magazine member 28 and having depending side walls 42 
and 43. The rearward portion 44 thereof being pivoted outside walls 25 and 
26 on pivot pin 31. Member 41 includes a driver 45, in the forward portion 
46 thereof for driving each successive, individual staple 36 down guidway 
33 onto anvil 23 all in a well known manner. Driver member 41 also 
includes a leaf spring 47 which rides on side walls 25 and 26 and spring 
biases the driver member upwardly away from the magazine member 28 as 
shown in FIG. 2. 
In this invention, the driver member includes a latch 48, of U shaped cross 
section which is slidably mounted on depending side wall 43 of driver 
member 41 to move longitudinally thereof, and the magazine member 28 
includes a side wise projecting detent 49 in rear of the latch, both being 
well forward toward the free ends of their respective members, as shown. 
Thus, instead of the conventional rearward latch location and rearward 
sliding release of the latch, in this invention the latch is moved forward 
and released by forward movement. As best shown in FIG. 4, the staple 
follower 37 is provided with an integral leg extension 51 having an 
integral upstanding lug 52 which engages the rear inside edge 50 of the 
latch 48, to move it forwardly and release the latch to cause the driver 
member 41 to spring up to the position shown in FIG. 2, when the staple 
follower is near the end of its path in the magazine 35. 
As shown in FIG. 5, I prefer to also provide a window 53 in the pad 54 of 
the handle 55, of the driver member 41, so that the exhaustion of staples 
is visible from above to the user. 
In FIG. 6, the driver member 56 is provided with a conventional latch 48 
which releases by rearward movement toward pivot pin 31, and a flexible 
strand 57 extends from the staple follower 37 rearwardly through a hole 77 
in back plate 78, then in a groove 79 around pivot pin 31, and then back 
to the latch 48. Thus, when the follower 37 nears the end of its path it 
exerts a rearward pull on latch 48 to release it from detent 49, spring 
open the driver member 41 and visually indicate exhaustion of staples. The 
strand 57 lies sinusously under coil spring 38 and rod 39 when slack, with 
staples fully loaded. 
A stapler 58 of the "Swingline" type is shown in FIG. 7, the parts being 
similar to those in the previous view except that the detents, such as 59, 
are undercut in the recesses such as 61 in the side walls such as 62 of 
the staple magazine member 63, and the latch means 64 is a pin 65 
longitudinally slidable in slots such as 66 in the side walls, such as 67 
of the driver member 68. 
In this type of stapler, the staple follower 69 is connected by coil spring 
71 to the pin 65, so that the pin 65 is normally urged rearwardly under 
detents 59, while the spring 71 also urges the staple follower 69 
forwardly toward the guideway 72. This structure is illustrated in FIG. 8 
wherein the driver member is shown held midway between open and closed 
position to illustrate the parts. 
As best shown in FIG. 9, the staple follower 69 is provided with a pair of 
upstanding lugs 73 and 74 which engage the pin 65 as the follower nears 
the end of its path toward the guideway 72, the lugs unseating the pin 65 
from under the detents 59 to release the driver member 68 from the 
magazine member 63 thereby indicating diminshed supply of staples. 
The release of the pin 65 causes the driver member 68 to pivot upwardly at 
a slight angle due to the spring 71 pulling the pin 65 upwardly and 
rearwardly along the inclined cam way 75 above the undercut 76, of the 
detents 59.