Abnormality-in-Stapling Detecting Mechanism of Electric Stapler

1. Field of the Invention

This invention relates to a detecting mechanism of an electric stapler for detecting an abnormal state in which sheets of paper are not normally fastened together with a staple or staples.

2. Description of the Related Art

Generally, an electric stapler of a built-in type used within a copying machine is actuated in accordance with control signals output by the copying machine. For this reason, regardless of a state in which staples discharged from the stapler are not normally driven through layers of paper to hold them together, the stapler continues the stapling operations in accordance with control signals output by the copying machine until there are produced a fixed number of pamphlets or booklets each of which is made by fastening the layers together. As a result, disadvantageously, cases occur in which many pamphlets inferior in stapling are produced or many staples unremovably stop up a portion of the stapler from which staples are discharged. As a countermeasure against it; there has been proposed an idea that the copying machine is provided with a detecting mechanism for ascertaining whether stapling has been normally carried out or not. However, due to various sizes of sheets of paper to be fastened together or an unfixed place at which the sheets are placed according to the size of the sheets, a plurality of stationary sensors and movable sensors are required, and thus the cost of production is raised.

Accordingly, another idea has been proposed that the built-in stapler is provided with such a detecting mechanism. In this mechanism, a clincher and legs of a staple are designed to be brought into contact with each other and, when they come in contact with each other, a switch is turned on to send out a detection signal of a normal state of fastening together. However, according to this mechanism, disadvantageously, the normal-state signal is sent out even when a hole of a stapler through which staples are discharged is plugged with staples, a staple discharging action of the stapler is carried out without a staple, or the legs of a staple are each bent in an opposite direction.

Further, according to the mechanism, cases frequently occur in which the normal-state signal is not sent out contrary to the fact that stapling has been normally carried out in a state of a driven staple being in contact with the clincher, because an adhesive agent used to stick staples together is an insulation and the surface of each staple is covered with the adhesive agent. Further, if an arrangement is adopted in which the normal-state signal is given by bringing the legs of a staple into contact with a pair of clinchers, respectively, it is necessary to insulate the clinchers from each other because of movement of the clinchers contiguous to each other. Accordingly, restrictions are placed on the construction of the mechanism.

It is an object of the present invention to provide a detecting mechanism mounted in an electric stapler which is capable of always and correctly detecting a state where stapling is abnormally carried out and is capable of being manufactured at low cost.

An abnormality-in-stapling detecting mechanism of an electric stapler according to the present invention comprises a stapling base on which sheets of paper are laid, a pair of movable clinchers rotatably mounted under an opening formed in the stapling base, and a driver for rotating each of the clinchers in a predetermined direction so as to press and clinch ends of legs of a staple. The opening receives the ends of the legs which have been driven through the sheets. The clinchers are each rotated in a direction opposite to the predetermined direction when the ends of the leas have been driven through the sheets. A detecting means is provided for detecting the rotation of the clinchers when the clinchers are each rotated in the direction opposite to the predetermined direction.

FIG. 1(a) is a front view of an abnormality-in-stapling detecting mechanism of an electric stapler according to the present invention, and FIG. 1(b) is a side view of FIG. 1(a).

FIG. 2(a) is a front view of the detecting mechanism which is working, and FIG. 2(b) is a side view of FIG. 2(a).

FIG. 3(a) is a front view of the detecting mechanism which is working, and FIG. 3(b) is a side view of FIG. 3(a).

FIG. 4 is an example showing how the detecting mechanism works when a staple is imperfectly driven into sheets of paper.

FIG. 5 is another example showing how the detecting mechanism works when a staple is imperfectly driven into the sheets.

An embodiment of the present invention will he described with reference to the attached drawings.

FIGS. 1(a) and 1(b) each show an abnormality-in-stapling detecting mechanism of an electric stapler. Reference numeral 1 designates a stapling base. Sheets 2 of paper to be fastened together are laid on the stapling base 1. In the stapling base 1, an opening 4 is formed for receiving the ends 3b of legs 3a of a staple 3 which have been driven through the sheets 2. A supporting plate 5 (not shown) is fixedly mounted under the opening 4. Shafts 7 are mounted on the supporting plate 5. A pair of movable clinchers 6A, 6B are rotatably attached to the shafts 7, 7, respectively. Behind the clinchers 6A, 6B, a driver 8 is disposed for rotating the clinchers 6A, 6B in predetermined directions (i.e., clockwise and counterclockwise, respectively). The clinchers 6A, 6B are each made up of a horizontal pressing part 6a situated under the opening 4 and a hook-shaped part 6b extending from the pressing part 6a downward. The clinchers 6A, 6B are each formed substantially C-shaped by the two parts 6a, 6b. The clinchers 6A, 6B are pulled toward each other by means of a spring 9. The clinchers 6A, 6B overlap at the ends 6c of the hook-shaped parts 6b.

The pressing parts 6a are arranged such that the ends 3b of the legs 3a of the staple 3 ere brought into contact with the respective surfaces of the pressing parts 6a when the legs 3a have been driven through the sheets 2.

The driver 8 comprises a driving link 10 and a cam 11 rotated by a driving mechanism (nut shown). The driving link 10 is rotated on a rotating shaft 13 mounted in the middle of the driving link 10, so that a front part 10a of the driving link 10 makes an up-and-down movement. The front part 10a of the driving link 10 is situated under the pressing parts 6a of the clinchers 6A, 6B, whereas a rear part 10b of the driving link 10 is engaged with an outer surface of the cam 11.

The rotation of the cam 11 by the driving mechanism (not shown) brings about the rotation of the driving link 10, thereby bringing about the up-and-down movement of the front part 10a of the driving link 10.

A reciprocative driver, a driving unit for reciprocating the driver, a magazine for staples 3, etc., (each not shown) are mounted over the stapling base 1. According to the reciprocation of the driver, the staple 3 is driven into and through the sheets 2.

A photosensor 12 is mounted under the opening 4 of the stapling base 1. The photosensor 12 comprises a light emitting diode 12a and a photodiode 12b which are arranged such that the ends 6c of the hook-shaped parts 6b of the clinchers 6A, 6B are placed between the light emitting diode 12a and the photodiode 12b. The photodiode 12b serves to receive a beam of light emitted by the light emitting diode 12a. When the clinchers 6A, 6B are not rotated (i.e., the clinchers 6A, 6B are in a state shown in FIG. 1), the ends 6c of the hook-shaped parts 6b intercept the beam of light from the light emitting diode 12a.

The driver 8 is actuated on the condition that the photodiode 12b has output a light-reception signal.

Action in the above embodiment will now be described.

The driver (not shown) is actuated and, as shown in FIG. 1(a), the legs 3a of the staple 3 are driven into the sheets 2. When the legs 3a have been driven through the sheets 2, the ends 3b of the legs 3a enter the opening 4 and come in contact with the respective surfaces of the pressing parts 6a of the clinchers 6A, 6B so as to push the pressing parts 6a, as shown in FIG. 2(a). By the push, the clinchers 6A, 6B are rotated against the force of the spring 9 in a direction opposite to a predetermined direction. In other words, when the legs 3a of the staple 3 have been normally driven through the sheets 2, the clincher 6A is rotated counterclockwise whereas the clincher 6B is rotated clockwise.

When the clinchers 6A, 6B are each rotated in the direction opposite to the predetermined direction, the ends 6c of the hook-shaped parts 6b of the clinchers 6A, 6B are separated from each other to release the interception of the beam of light emitted by the light emitting diode 12a, as shown in FIG. 2(a).

In other words, when the legs 3a have been normally driven through the sheets 2, the photosensor 12 detects that the legs 3a have been normally driven through the sheets 2.

According to the detection, the driver 8 is actuated to rotate the cam 11. According to this rotation of the cam 11, the driving link 10 is rotated to move the front part 10a thereof upward as shown in FIGS. 3(a) and 3(b) and thereby the clinchers 6A, 6B are each rotated in the predetermined direction.

In other words, the clincher 6A is rotated clockwise whereas the clincher 6B is rotated counterclockwise. According to these rotations, the pressing parts 6a of the clinchers 6A, 6B are moved upward. Since the ends 3b of the legs 3a of the staple 3 are in contact with the surfaces of the pressing parts 6a, 6a, respectively, the ends 3b of the legs 3a are pressed and bent inward as the pressing parts 6a are moved upward. As a result, the ends 3b of the legs 3a are clinched, and the stapling is completed.

When the front part 10a of the driving link 10 reaches a top dead point, the ends 6c of the hook-shaped parts 6b again intercept the beam of light emitted by the light emitting diode 12a. After that, the front part 10a of the driving line 10 returns to an initial position (shown in FIGS. 1(a) and 1(b)) a little below the top dead point and, for next stapling, the clinchers 6A, 6B also return to an initial position shown in FIGS. 1(a) and 1(b).

If the staple 3 is bent into an M-shape as shown in FIG. 4 and therefore the legs 3a of the staple 3 cannot be driven through the sheets 2 or, as shown in FIG. 5, only one of the legs 3a is driven therethrough, both the clinchers 6A, 6B cannot be rotated or only one of the clinchers 6A, 6B can be rotated. In this case, at least one of the ends 6c of the clinchers 6A, 6B keeps intercepting the beam of light emitted by the light emitting diode 12a and accordingly the photosensor 12 does not detect that the legs 3a of the staple 3 have been normally driven through the sheets 2.

Accordingly, since a detection signal is not sent out which shows that stapling is normally carried out during one cycle of stapling, abnormality in stapling is detected. Accordingly, since the driver 8 is not actuated, stapling is stopped.

On the condition that a beam of light emitted by the light emitting diode 12a is intercepted (i.e., the ends 3b of the legs 3a of the staple 3 have been normally clinched), the photosensor 12 may output a detection signal of normality in stapling after the photodiode 12b outputs a light-reception signal which shows that the legs 3a of the staple 3 has been normally driven through the sheets 2. In addition, the position of the photosensor 12 is not limited to that indicated above. For example, a plurality of photosensors 12 may be disposed at places indicated by the broken lines in FIG. 1(a), respectively.