Staple refill cartridge for electric stapler

Abstract: A staple refill cartridge for an electric stapler via a cartridge is releasably attached to the electric stapler and made of paper for replenishing sheet staples (4) formed by uniting straight staples together in sheet form, and the refill cartridge (A) includes: two lateral wall portions (1); a rear wall portion (2) formed between the two lateral wall portions (1) into a continuous body; and an overlapping piece (2b) having substantially the same size as the rear wall portion (2) the overlapping piece (2b) being overlapped inside the rear wall portion (2), wherein a corner portion (P) is formed by each of the two lateral wall portions (i) and each of both lateral ends of the overlapping piece (2b).

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a refill cartridge according to the pre-characterising portion of claim 1 which is designed to be releasably attached to an electric stapler via a cartridge for replenishing consumed staples. A refill cartridge of this type is known from EP-A-608 756. 2. Description of the Related Art Conventionally, staples for electric staplers are supplied from a synthetic resin-formed cartridge in which the staples are contained. When the staples have been used up, the cartridge is replaced with a new one. As a result, the cartridge whose staples have been consumed is destined to be scrapped, addressing an environmental problem. To overcome this problem, a new type of cartridge has been proposed. A refill cartridge that is refillable to the cartridge contains staples so that the cartridge can no longer be wasted every time the whole staples have been consumed. By the way, the staples loaded into the refill cartridge are such that straight staples are united together in sheet from. A plurality of such sheets are layered one upon another. Therefore, a known refill cartridge (EP-A-608 756) that is formed by folding a sheet of paper includes a corner fold P1 that is projected as shown in Fig. 7(a) or a corner fold P2 that is rounded as shown in Fig. 7(b), which corner folds being the folds between the lateral wall portion and the rear wall portion. As a result, a corner portion 20a of a sheet staple 20 is caught up by such corner fold of the refill cartridge so that the sheet staple 20 cannot move downward smoothly, which in turn imposed the problem of blocking staple forwarding or breaking the sheet staple. A similar refill cartridge made of plastics is shown in EP-A-637 487 which is a prior art document within the meaning of Article 54(3) EPC. SUMMARY OF THE INVENTION The invention has been made to overcome the aforementioned problem. The object of the invention is, therefore, to provide a staple refill cartridge for an electric stapler which allows sheet staples within the refill cartridge to move reliably and smoothly at all times even if the refill cartridge is formed by folding a sheet of paper. To achieve the above object, the invention provides a staple refill cartridge for an electric stapler with an overlapping piece inside of the rear wall portion, thus preventing the contact between the corner portions of the staple sheets and the corner folds of the paper refill cartridge. According to the invention, a total of three wall portions, i.e., both lateral wall portions and the rear wall portion, are made continuous to each other when the original sheet is shaped by folding. However, since the overlapping piece having substantially the same size as the rear wall portion is overlapped inside the rear wall portion in the middle, the rear wall portion is doubled. Therefore, the corner of a sheet staple loaded into the refill cartridge corresponds to the corner portion formed between the inside rear wall portion that is formed by the overlapping piece and each lateral wall portion. However, this corner portion, not being continuous, is neither projected nor rounded. Hence, when the sheet staple is loaded into the refill cartridge, the corners of the sheet staple are not caught up by the corner portions of the refill cartridge, allowing the sheet staples to move downward smoothly as well as reliably at all times. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1(a) and 1(b) are perspective views showing a preferred embodiment of a refill cartridge according to the invention as viewed from top and bottom; Fig. 2 is a development of the refill cartridge; Fig. 3 is a plan view of the refill cartridge; Fig. 4 is an enlarged perspective view of a corner portion of the refill cartridge; Fig. 5 is an enlarged view of a corner portion of the refill cartridge; Fig. 6 is a perspective view showing a state in which the refill cartridge is loaded into a cartridge of an electric stapler; and Figs. 7(a) and 7(b) are perspective views showing a conventional refill cartridge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figs. 1(a) and 1(b) are perspective views showing a refill cartridge of the invention as viewed in different directions. This refill cartridge is constructed of both lateral wall portions 1, a rear wall portion 2, and a bottom wall portion 3, and is designed to refill sheet staples 4 while releasably attached to a cartridge. Each sheet staple 4 is formed by uniting untwisted, straight staples together in sheet form, and is accommodated in the refill cartridge in layers. A binding tape 5 is wound integrally around the sheet staples 4 and the refill cartridge A. It may be noted that the binding tape 5 is removed once the sheet staples 4 have been attached to the cartridge described later. The refill cartridge is formed by folding an original sheet 6 that has such a shape as shown in Fig. 2 in developed form. More specifically, the original sheet 6 for the refill cartridge includes, as shown in Fig. 2, a rear wall piece 2a that is in the middle, lateral wall pieces 1a continuous to the rear wall piece 2a through folding lines a, an overlapping piece 2b continuous to the rear wall piece 2a through a folding line b, and bottom pieces 3a continuous to the lateral wall pieces la through folding lines c. The rear wall piece 2a and the overlapping piece 2b are formed so as to be substantially symmetrical with respect to the folding line b. While the width of the overlapping piece 2b is set to substantially the same value as the width of the rear wall piece 2a, it is preferred to make the width of the overlapping piece 2b slightly smaller as shown in Fig. 2. It may be noted that a notch 7 of each bottom piece 3a is provided for positioning at the time of bonding the pieces together; holes 9 and 10 that are symmetrical with respect to the line b in both the rear wall piece 2a and the overlapping piece 2b are provided to retain the refill cartridge in retaining portions (not shown) formed on the refill cartridge accommodating section of the cartridge; and notches 11 and 12 are provided to allow a staple forwarding member (not shown) to escape therethrough, the notches 11 of the rear wall piece 2a being formed slightly smaller than the notches 12 of the overlapping piece 2b. In addition, a middle opening 13 that is symmetrical with respect to the line b in the rear wall piece 2a and the overlapping piece 2b is provided for detection with a remaining sheet staple detecting device arranged in a cartridge accommodating section of a magazine. It is preferred to make perforations along the folding lines so that correct folding can be achieved. For forming the refill cartridge out of the original sheet 6 in developed form, the following steps are taken. The lateral wall pieces 1a and the bottom pieces 3a are folded along the folding lines a, c inward, respectively, so as to be at right angles to each other; the bottom pieces 3a are overlapped one upon the other and bonded to each other so that the notches 7 coincide; and the overlapping piece 2b is folded 180° inward from the folding line b so as to be overlapped on the rear wall piece 2a (see Figs. 3 and 4). It may be noted that the rear wall portion 2 is constructed of the rear wall piece 2a and the overlapping piece 2b. Further, it is proposed that the lower end of the overlapping piece 2b be inserted into a gap 14 formed between the lower end of the lateral wall portions 1 constructed of both lateral wall pieces la and the rear end of the bottom wall portion 3 constructed of the bottom piece 3a. As described above, the refill cartridge is thus formed by folding and bonding the original sheet 6, so that a total of three wall portions, i.e., both lateral wall portions 1 and the rear wall portion 2 are formed into a continuous body. However, since the overlapping piece 2b that has substantially the same size as the rear wall portion 2 is overlapped in the inner side of the rear wall portion 2 in the middle, the rear wall portion 2 is doubled, forming a corner between each lateral wall piece la and each of lateral ends of the overlapping piece 2b inside a corner fold P formed by a fold between each lateral wall piece 1a and the rear wall piece 2a. Further, as shown in Fig. 5, a gap 15, although very small, is formed between the side end of the overlapping piece 2b and each lateral wall portion 1. The inner corners, not being continuous as described above, are neither projected nor rounded as in the case of the outer corner fold P (the conventional corner fold). Therefore, when the sheet staples 4 are loaded into the refill cartridge, there occurs no inconvenience of catching the corner portions 4a of the sheet staples 4 by the corner folds of the refill cartridge. Hence, the sheet staples 4 move downward always smoothly, which in turn implements reliable forwarding. While the inside rear wall portion 2 is formed by folding the overlapping piece 2b in the above embodiment, the invention can be applied to a construction that the overlapping piece is formed as a separate piece from the rear wall piece so that the overlapping piece can be bonded to the rear wall piece while overlapped inside the rear wall piece. The thus constructed refill cartridge is accommodated in a cartridge 16 shown in Fig. 6. This cartridge 16 has an accommodating section 17 of a refill cartridge A and is releasably attached to the main body of an electric stapler. The electric stapler main body is not shown in the drawing. The refill cartridge A is accommodated in the accommodating section 17 of the cartridge 16 in the following steps. The refill cartridge A is inserted into the accommodating section 17 with the binding tape 5 wound around the refill cartridge A. After the refill cartridge A has been accommodated, the binding tape 5 wound around the sheet staples 4 is first released at the bonded portion thereof by pulling a tab 5a thereof, and then completely removed by further pulling the tape 5 out in a single direction.

Claims: A staple refill cartridge (A) for an electric stapler equipped with a cartridge (16), said refill cartridge (A) being releasably attached to the electric stapler via the cartridge (16) and made of paper for accommodating a pack of sheet staples (4), each sheet staple being formed by uniting straight staples together in sheet form having corner portions (4a); said refill cartridge (A) comprising two lateral wall portions (1a) and a rear wall portion (2a) formed between said two lateral wall portions (la) by corner folds (P) into a continuous body (6), the inner portions of the corner folds being in use adjacent to corner portions (4a) of the sheet staples (4), characterized by an overlapping piece (2b) having substantially the same size as the rear wall portion (2a) and covering its inside, said overlapping piece (2b) preventing corner portions (4a) of the sheet staples (4) from contacting said inner portions of said corner folds (P). A staple refill cartridge (A) according to claim 1, wherein said overlapping piece (2b) is formed with said continuous body (6). A staple refill cartridge (A) according to claim 1, wherein said overlapping piece (2b) is separate from said continuous body (6). A staple refill cartridge (A) according to claim 1, wherein the width of said overlapping piece (2b) is smaller than the width of said rear wall portion (2a). A staple refill cartridge (A) according to claim 1, wherein each of said lateral wall portions (1a) includes a bottom piece (3a) at the bottom thereof. A staple refill cartridge (A) according to claim 5, wherein the lower end of said overlapping piece (2b) is inserted into a gap (14) formed between said lateral wall portions (1a) and said bottom pieces (3a). A staple refill cartridge (A) according to claim 1, further comprising a binding tape (5) wound integrally around the sheet staples (4) and the staple refill cartridge (A).

Inventors: TAKAHASHI KAZUO, YOSHIE TORU, TAKAHASHI, KAZUO, YOSHIE, TORU, Takahashi, Kazuo, c/o Max Co., Ltd., YOSHIE, TORU, C/O MAX CO., LTD.
Applicants: MAX CO LTD, MAX CO., LTD.
Application year: 1995
Main classification: B25C5
IPC codes: B25C5, B65D5