GB2248577A

GB2248577A - Paper-shearing device

Info

Publication number: GB2248577A
Application number: GB9022253A
Authority: GB
Inventors: Kun-Nan Lo
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-10-12
Filing date: 1990-10-12
Publication date: 1992-04-15
Also published as: GB9022253D0

Abstract

A paper shearing device includes a power operated active blade (20) having an inclined blade edge (21) and a passive blade (30) having a second blade edge (34). A bolt (40) fastens the passive blade (30) to a stationary positioning plate (13) in a limitedly movable position with a resilient piece (50) located between the stationary positioning plate (13) and the passive blade (30) which provides easy relative adjustment of the blades. The resilient piece (50) urges the passive blade (30) to a position that permits the inclined blade edge (21) to contact the second blade edge (34) when the blade (20) is moved towards the passive blade (30) to effect shearing. Further movement of the blade (20) pushes the passive blade (30) against the action of the resilient piece (50), as a web of paper (11), particularly in a fax machine, is sheared. <IMAGE>

Description

PAPER SHEARING DEVICE The invention relates to a paper shearing device, more particularly to a paper shearing device to be used in a fax machine.

Figure 1 is an illustration of the type of paper shearing device conventionally installed in fax machines or printers. One leg of a substantially Lshaped passive blade member 3 is attached to a stationary base plate 1. An active blade member 4 is provided opposite the passive blade member 3. The active blade member 4 is movably actuated by a motor (not shown) to move the same towards or away from the passive blade member 3 to effect shearing of a length of paper 2 disposed between the passive and active blade members 3 and 4.

A main disadvantage of the conventional paper shearing device is that the position of the passive blade member 3 relative to the active blade member 4 must be properly maintained, otherwise, the effectiveness of the paper shearing device will suffer.

Referring to Figure 2, when the clearance between the blade members 3 and 4 is too wide, paper shearing cannot be accomplished. The wide clearance condition usually occurs after frequent use of the device since the mountings of both blade members 3 and 4 tend to loosen after a long period of use. Therefore, periodic maintenance checks should be made to ensure proper positioning of the two blade members 3 and 4.

Figure 3 illustrates anqther improper arrangement of the passive and active blade members 3 and 4. In a condition of insufficient clearance, the passive blade member 3 prevents movement of the active blade member 4 towards the same, thereby making the device inefficient in its task. The resulting friction between the two blade members 3 and 4 can damage or break both blade members 3 and 4. And since further movement of the active blade member 4 is prevented, the motor which powers the active blade member 4 is overloaded, thereby damaging the same.

Therefore, the clearance between the passive and active blade members 3 and 4 is a critical factor in ensuring the effective operation of the conventional paper shearing device. The device is ineffective if the clearance between the two blade members is too wide or when no clearance exists. Thus, adjustment of the relative positions of the passive and active blade members 3 and 4 must be precise to ensure proper operation of the device.

The objective of the present invention is to provide a paper shearing device which is effective even when no clearance exists between its active and passive blade members, thereby making the adjustment of the relative positions of the blade members easier.

Accordingly, the preferred embodiment of a paper shearing device of the present invention comprises a power operated active blade member having an inclined blade edge, and a passive blade member provided opposite the active blade member and having a second blade edge. The active blade member is movable towards the passive blade member to shear a length of paper disposed between the inclined blade edge and the second blade edge. A stationary positioning plate is provided adjacent to the passive blade member. A bolt slidably passes through the stationary positioning plate and engages the passive blade member to permit limited movement of the passive blade member. A substantially S-shaped resilient curved plate is disposed between the stationary positioning plate and the passive blade member.The resilient plate urges the passive blade member to a position that permits the inclined blade edge of the active blade member to contact the second blade edge when the active blade member moves towards the passive blade member to effect shearing. Movement of the active blade member towards the passive blade member pushes the passive blade member against the action of the resilient piece.

Other features and advantages of this invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, in which: Figure 1 is a side view of a conventional paper shearing device; Figure 2 is a side view of the conventional paper shearing device shown in Figure 1 illustrating the operation of the device when there is a wide clearance between its blade members; Figure 3 is a side view of the conventional paper shearing device shown in Figure 1 illustrating the operation of the device when there is no clearance between its blade members; Figure 4 is a side partly sectional view of the preferred embodiment of the paper shearing device according to the present invention; Figure 5 is an exploded view of a portion of the paper shearing device illustrated in Figure 4; and Figures 6 and 7 illustrate the shearing operation of the preferred embodiment.

Referring to Figure 4, the preferred embodiment of a paper shearing device according to the present invention is shown to comprise a base plate 10, an active blade member 20, a passive blade member 30, fastening pieces 40, and a resilient piece 50.

The base plate 10 has a horizontal plate portion 12 mounted inside a fax machine at the base of the same. A roll of fax paper 11 is disposed inside the fax machine and a portion of the fax paper 11 is positioned above the horizontal plate portion 12. The width of the horizontal plate portion 12 exceeds that of the fax paper 11. The base plate 10 is stationary relative to the fax machine and has a substantially perpendicular positioning portion 13 provided on a rear end of horizontal plate portion 12. The positioning portion 13 has a plurality of spaced and aligned through holes 14 provided along its width.

The active blade member 20 is movably provided above the horizontal plate portion 12 and the fax paper 11.

The width of the active blade member 20 also exceeds that of the fax paper 11. One end of the active blade member 20 is provided with an inclined blade edge 21.

The other end of the active blade member 20 is provided with a shaft 22. The active blade member 20 is driven by a motor via the shaft 22, and is thus moved toward or away from the horizontal plate portion 12.

The passive blade member 30 has a slide plate 31 in sliding contact with the horizontal plate portion 12, and a blade portion 32 provided on one end of the slide plate 31 adjacent to the positioning portion 13 of the base plate 10. The blade portion 32 has a plurality of threaded holes 33 which are aligned with the through holes 14 of the base plate 10.

Each of the fastening pieces 40 includes a bolt slidably passing through one of the through holes 14 of the base plate 10. Each fastening piece 40 has a head portion 41 abutting the positioning portion 13 of the base plate 10 and a threaded end engaging one of the threaded holes 33 of the passive blade member 30. The fastening pieces 40 thus allow limited movement of the passive blade member 30 relative to the positioning plate portion 13.

The resilient piece 50 is disposed between the blade portion 32 of the passive blade member 30 and the positioning portion 13 of the base plate 10. Referring to Figure 5, the resilient piece 50 is a substantially S-shaped curved plate having one end 51 in contact with the blade portion 32 of the passive blade member 30, another end 52 in contact with the positioning portion 13 of the base plate 10, a first curved face 53 abutting the positioning portion 13, and a second curved face 54 provided opposite the first curved face 53 and abutting the blade portion 32. The resilient piece 50 further has a plurality of central through holes 55 aligned with the through holes 14 and the threaded holes 33 of the base plate 10 and the passive blade members 30 to allow the fastening pieces 40 to slidably pass through.

Referring to Figures 4 and 6, the resilient piece 50 urges the passive blade member 30 to a position that permits the inclined blade edge 21 of the active blade member 20 to contact a blade edge 34 of the blade portion 32 of the passive blade member 30 when the active blade member 20 moves towards the passive blade member 30. The active blade member 20 thus pushes the passive blade member 30 against the action of the resilient piece 50. Further movement of the active blade member 20 towards the passive blade member 30 causes the ceasing of contact between the inclined blade edge 21 and the blade edge 34 to effectively and smoothly shear the fax paper 11 disposed between the inclined blade edge 21 and the blade edge 34, as shown in Figure 7.

Thus, although there is contact between the active and passive blade members 20 and 30, the passive blade member 30 does not prevent the movement of the active blade member 20, thereby permitting the accomplishment of the shearing function of the device while minimizing damages to the two blade members 20 and 30. Another advantage resulting from the use of the paper shearing device of the present invention is that the relative position of the active and passive blade members 20 and 30 is not critical, unlike that of conventional paper shearing devices. Thus, adjustment of the relative position of the two blade members 20 and 30 can easily be accomplished.

Claims

I CLAIM:

1. A paper shearing device comprising a power operated active blade member having an inclined blade edge, a passive blade member provided opposite said active blade member and having a second blade edge, said active blade member being movable towards said passive blade member to shear a length of paper disposed between said inclined blade edge and said second blade edge, and improvements, wherein: said paper shearing device further comprises a stationary positioning plate provided adjacent to said passive blade member, means for fastening said passive blade member to said stationary positioning plate in a limitedly movable position, and a resilient piece disposed between said stationary positioning plate and said passive blade member; said resilient piece urging said passive blade member to a position that permits said inclined blade edge to contact said second blade edge when said active blade member moves towards said passive blade member to effect shearing; movement of said active blade member towards said passive blade member being capable of pushing said passive blade member against the action of said resilient piece.

2. The paper shearing device as claimed in claim 1, wherein said stationary positioning plate has a through hole and said passive blade member has a threaded hole aligned with said through hole; said fastening means comprising a bolt slidably passing through said through hole and engaging said passive blade member at said threaded hole.

3. The paper shearing device as claimed in claim 2, wherein said resilient piece is a substantially Sshaped curved plate having a central second through hole, said bolt slidably passing through said resilient piece at said central second through hole.

4. The paper shearing device as substantially described hereinbefore with reference to the accompanying drawings.