Sheet material cutting device

A sheet material cutting mechanism for cutting sheet materials two rotary blades and a mechanism for pressing down a sheet material to be cut. When the motor is started, a screw shaft 2 rotates, and a rotary blade assembly 4 starts to move to the right in FIG. 1 . Then, the roller 12 rotates by friction with a frame 1, and a first rotary blade 10 rotates by the rotation of a roller. At the same time, a second rotary blade 20 also rotates by the frictional force generated between the rubber roller 22 and the frame 1. The sheet material, fed into the sheet material receiving portion 17, is pressed by the rubber roller 22 against the surface 5 of the frame 1 immediately before cutting to prevent lifting or bending of the sheet material, thereby producing satisfactory cutting of the sheet material.

BACKGROUND OF THE INVENTION 
The present invention relates to a sheet material cutting device to cut 
sheet material by the cooperation of two rotary blades which travel while 
rotating. 
In a printer for a terminal such as an ECR or a POS, strip-shaped sheet 
material wound into a roll is pulled out for printing, and then the 
necessary portion is cut by a cutter into a sheet for delivery. 
Various types of such sheet material cutting device are available. A rotary 
cutter requires high manufacturing costs and causes a relatively high 
degree of noise and, therefore, is now being replaced by a cutter 
featuring a combination of a circular rotary cutting blade moving while 
rotating and a fixed cutting blade formed into a long sheet. 
The prior art sheet material cutting device of this type will be described 
below with reference to FIG. 8A and 8B. As shown in FIG. 8A, a supporting 
member 101 with a rotary blade 102 travels horizontally along a screw 
shaft 100. In FIG. 8B, the rotary blade 102 is rotatably bearing-supported 
on a shaft 104 mounted on the supporting member 101 and pressed against a 
fixed blade 103 by means of a spring 104. In FIG. 8A again, sheet 
material, fed in the vertical direction to the paper on which said figure 
appears, is cut by the rotary and the fixed blade as the supporting member 
travels horizontally. 
With this type of cutting device, it is important, in order to cut the 
sheet material sharply, that the rotary blade 102 is slightly inclined 
toward the fixed blade 103 as shown in FIGS. 9 and 10, so that the 
periphery of the rotary blade 102 comes into contact with the edge of the 
stationary blade at a certain point P in the traveling direction of the 
rotary blade. Furthermore, when one wishes to cut a sheet material by both 
the forward and backward travel of the rotary blade 102, a means to switch 
the inclination of the rotary blade between the forward and backward 
travel is necessary. This type of device is actually proposed in, for 
example, the Japanese Examined Patent No. 50-24466/1975. The drawback of 
this device is that switching the rotary blade is complex and expensive 
because the rotary blade is switched for necessary inclination by using 
additional components such as a wire stretched horizontally or a lever 
oscillating around a pivot shaft. 
To solve the above problems of conventional devices, the inventors of the 
present invention have already proposed a sheet material cutting device as 
described in U.S. Pat. No. 5,307,716. This device permits satisfactory 
cutting of strip-shaped sheet material such as paper by simply causing the 
rotary blade to incline by the angle necessary for cutting, in both the 
forward and the backward motion of the rotary blade, by the cooperation of 
the circular rotary blades moving while rotating, a roller for rotating 
the rotary blade, and a roller guide. 
However, the above device has no mechanism to prevent lifting of the sheet 
material when it is being cut. Thus, sheet material would be lifted from 
the fixed blade or bent, thus preventing satisfactory cutting. 
Furthermore, depending on the contact between the rotary and the fixed 
blade, wearing of the cutting edge of the fixed blade is not always 
uniform over the entire length. This also prevents satisfactory cutting of 
the sheet material. 
SUMMARY OF THE INVENTION 
Against this background, the inventors of the present invention have 
improved the above-mentioned sheet material cutting device and have 
developed a sheet material cutting device with a new mechanism solving all 
of the above problems. This sheet material cutting device with the new 
mechanism permits cutting of sheet material by the cooperation of two 
rotary blades, and one of said two rotary blades, the one opposite to the 
frame, is provided with a rubber roller coaxially mounted on its shaft to 
press the sheet material to be cut against the frame. This device permits 
satisfactory cutting of sheet material by the cooperation of the two 
rotary blades, and the sheet material to be cut is pressed against the 
frame by the above-mentioned rubber roller immediately before the sheet 
material is cut, so that the sheet material to be cut is prevented from 
lifting or bending when it is cut, thereby assuring a sharp cut of the 
sheet material. 
For this reason, the first technical solution adopted by the present 
invention is a sheet material cutting device wherein a sheet material 
cutting means comprises: a rotary blade supporting member slidably mounted 
on a frame; a first and a second rotary blade mounted on said supporting 
member; a spring member to keep the cutting edges of both said rotary 
blades pressed against each other; and a driving mechanism to rotate said 
first and second rotary blades by the movement of said rotary blade 
supporting member, and designed to cut a sheet material by the cooperation 
of said first and second rotary blades while said sheet material cutting 
means moves along said frame. 
The second technical solution adopted by the inventors of the present 
invention is a sheet material cutting device with a sheet material cutting 
means comprising a rotary blade supporting member slidably mounted on a 
frame; a first and a second rotary blade mounted on said supporting 
member; a spring member to keep the cutting edges of both said rotary 
blades pressed against each other; and a driving mechanism to rotate said 
first and second rotary blades by the movement of said rotary blade 
supporting member; wherein said driving mechanism to rotate the rotary 
blades comprises a roller mounted between said frame and the first rotary 
blade in contact with both the frame and the first rotary blade, and a 
rubber roller mounted coaxially with the second rotary blade having a 
larger diameter than that of the second rotary blade and pressed against 
said frame.

PREFERRED EMBODIMENT OF THE INVENTION 
In FIGS. 1A and 1B, when the motor in the drive unit starts and the screw 
shaft 2 rotates, the sheet material cutting mechanism 4 moves to the 
right; the roller 12 rotates by the frictional force with the frame 1; and 
the first rotary blade rotates as the roller 12 rotates. Simultaneously, 
the second rotary blade 20 rotates by the frictional force between the 
rubber roller 22 and the frame 1. As a sheet material enters the sheet 
material receiving portion 17, the rubber roller 22 presses the sheet 
material, immediately before cutting, against the surface 5 of the frame 1 
to prevent lifting or bending of the sheet material, with the result that 
the sheet material is cut by the cooperation of the two rotary blades 10 
and 20. The two rotary blades 10 and 20 are pressed against each other by 
a certain spring force by springs 16 and 24, respectively, with the result 
that the sheet material is cut satisfactorily. 
In the stand-by state, the sheet material cutting mechanism 4 is always at 
either end of the frame 1 under the control of driving motor. In the 
stand-by position, the rubber roller 22 rests on a recess 7 formed on the 
frame 1 to prevent permanent deformation. 
The first embodiment of the present invention is described below with 
reference to the drawings. 
FIG. 1A is a plan view and FIG. 1B is a side view of a sheet material 
cutting device as the first embodiment of the present invention. 
In FIG. 1A, frame 1 supports a screw shaft 2 at both ends. A driving device 
3 is mounted on one end of the screw shaft 2 to rotate the screw shaft 2. 
The driving device 3 comprises a motor and a transmission mechanism to 
transmit the rotational force of the motor to the screw shaft 2. 
A sheet material cutting mechanism 4 is thread-engaged with the screw shaft 
2. The sheet material cutting mechanism 4 is slidably supported by the 
guide on the frame without "play," as will be described later. In this 
first embodiment, the motor starts; the screw shaft 2 rotates; and the 
sheet material cutting mechanism 4 moves to the right in FIG. 1A to permit 
cutting of the sheet material between the two rotary blades. The sheet 
material cutting mechanism 4 returns to the waiting position without 
cutting a sheet material when the screw shaft 2 rotates reversely. The 
horizontal reciprocation of the sheet material cutting mechanism 4 is 
actuated by rotating the screw shaft 2 back and forth by the forward and 
reverse rotation of the motor or, by switching the transmission mechanism. 
Alternatively, the sheet material cutting mechanism 4 can reciprocate 
along the screw shaft 2, without changing the direction of motor rotation, 
by using continuous right- and left-hand threads on the screw shaft 2. 
The above-mentioned sheet material cutting mechanism 4 is provided with two 
rotary blades (with a construction described later) to cut sheet material 
between them and a rotary blade supporting member to hold said rotary 
blades. 
The construction of the above sheet material cutting mechanism 4 is 
described below. 
FIG. 2 is a plan view of the sheet material cutting means. FIG. 3 is a 
cross-sectional view of the section A--A in FIG. 2. FIG. 4B is a plan view 
of the rotary blade supporting member and FIG. 4A is a cross-sectional 
view of the section B--B in the plan view. 
In FIG. 2, 1 frame 1 supports, as described earlier, the screw shaft 2 at 
both ends. The frame 1 has a cross section as shown in FIG. 3. It has a 
surface 5 on which the sheet material to be cut is placed, and a guide 6 
for guiding the rotary blade supporting member 4a. The frame 1 further has 
a recess 7 on each end as shown in FIG. 1 to prevent permanent deformation 
of the rubber roller (described later) when it is in the rest position. 
The recess 7 is provided to release the rubber roller and prevent 
permanent deformation when the rotary blade supporting member 4a is 
situated at the end of the frame 1. When the rotary blade supporting 
member 4a is positioned at either end of the frame 1, the rubber roller 
rests on the recess 7 formed on the frame 1 and is released from 
deformation. 
FIGS. 4A and 4B show the rotary blade supporting member 4a which is 
slidably mounted on the above-mentioned frame 1. 
In FIGS. 4A and 4B the rotary blade supporting member 4a comprises an 
integrally formed supporting member 4a and a cover 4b fitted to the 
supporting member 4a. As shown in the figure, the rotary blade supporting 
member 4a provides a threaded portion 4c to thread-engage itself with the 
above-mentioned screw shaft and a guide groove 4d which slidably fits onto 
the guide 6 of the frame 1. A bearing to hold the shaft 11 of the first 
rotary blade 10 is formed on the upper side (to the right in the figure) 
of the guide groove 4d. The above-mentioned rotary blade supporting member 
4a further provides a space 13 to accommodate a roller which causes the 
first rotary blade 10 to rotate. 
The roller 12, which is accommodated in the space 13 and placed between the 
frame 1 and the first rotary blade 10, maintains contact with the upper 
surface of the guide 6 of the frame and with the back side of the first 
rotary blade 10. When the rotary blade supporting member 4a travels along 
the frame 1, the roller 12 rotates due to frictional force with the guide 
6 on the frame. The first rotary blade 10 also rotates due to frictional 
force as the roller 12 rotates. 
A bearing 14 is provided through the wall of the above-mentioned rotary 
blade supporting member 4a to support the second rotary blade 20. A cover 
4b with a bearing hole 15 can be mounted opposite to the bearing 14. 
Further, the rotary blade supporting member 4a is provided with a sheet 
material receiving portion 17. 
Rotary shafts 11 and 21 for the first and the second rotary blades 10 and 
20, respectively, are mounted on the rotary blade supporting member 4a of 
the above construction as shown in FIGS. 2 and 3. The first rotary blade 
10 is pressed in the shaft direction (to the left in the figure) by a 
plate spring. The shaft 11 for the first rotary blade 10 is mounted 
loosely so that it is at a slight incline with reference to the rotary 
blade supporting member 4a. The roller 12 located between the first rotary 
blade 10 and the frame guide 6 is pressed against the surface of the frame 
guide 6 by the spring force of the above-mentioned plate spring 16 via the 
first rotary blade 10. In other words, the roller 12 is supported by the 
first rotary blade 10 and the surface of the frame guide 6 when assembled, 
as shown in FIG. 3. As a result of this construction, when the screw shaft 
2 rotates and the rotary blade supporting member 4a moves, the roller 12 
rotates due to frictional contact with the frame 1, and the rotating force 
of the roller 12 is transmitted to the first rotary blade 10 to cause it 
to rotate. It is desirable to keep the back side of the first rotary blade 
10, the roller surface, and that area of the guide surface 6 of the frame 
that is in contact with the roller in a state that is suitable for 
producing an adequate frictional force. 
The second rotary blade 20 and the rubber roller 22 are mounted on a 
bearing 23. The bearing 23 is rotatably and slidably mounted on a shaft 
21. The shaft 21 is supported by the rotary blade supporting member 4a and 
the hole 15 through the cover 4b. The outside diameter of the rubber 
roller 22 is larger than that of the second rotary blade 20. This is 
necessary for the rubber roller 22 to press by deforming the sheet 
material S against the surface 5 of the frame 1 when the sheet material 
cutting mechanism 4 moves (see FIG. 2). 
The second rotary blade 20 and the rubber roller 22 are pressed to the 
right in FIG. 3 by a spring 24, with the result that the back side of the 
first rotary blade 10 and the front surface of the second rotary blade 20 
come into contact with each other under appropriate contact pressure. The 
rubber roller 22 is integrally constructed with the second rotary blade 20 
in the present embodiment but these may be separate components. Further, 
the spring 24, pressing the second rotary blade 20 upward may be different 
from what is shown in the figure; various other types of springs may be 
used provided the same function is achieved. 
The first and the second rotary blade 10 and 20 are assembled into the 
rotary blade supporting member of the above construction as shown in FIGS. 
2 and 3, making up the sheet material cutting mechanism 4. In this 
instance, the shaft 11 of the first rotary blade 10 is mounted slightly 
behind in the cutting direction as shown in FIG. 2. This is necessary to 
make the sheet material receiving portion 17 formed on the rotary blade 
supporting member longer. 
The operation of the sheet material cutting device as the first embodiment 
of the present invention is described below. 
In FIG. 1A, assume the sheet material cutting mechanism 4 moves to the 
right along the frame 3. The motor (not shown) starts; the screw shaft 2 
starts to rotate; the sheet material cutting mechanism 4 starts to move to 
the right; the roller 12 rotates by the frictional force between said 
roller and the frame 1, and the first rotary blade 10 starts to rotate as 
the roller 12 rotates. At the same time, the second rotary blade 20 
rotates by the frictional force between the rubber roller 22 and the frame 
1. The sheet material to be cut enters the sheet material receiving 
portion 17. In this instance, the sheet material is pressed against the 
surface 5 of the frame 1 by the rubber roller 22 immediately before 
cutting so that the sheet material will not be lifted or bent but will be 
satisfactorily cut by the cooperation of the two rotary blades 10 and 20. 
The two rotary blades 10 and 20 are in contact with each other under a 
specified force applied by springs 16 and 24, respectively, permitting 
satisfactory cutting of the sheet material. 
In the present embodiment, the motor is controlled so that the sheet 
material cutting mechanism 4 will always rest on either end of the frame 1 
in the waiting state of the device. In the waiting position, the rubber 
roll 22 rests on a recess 7 formed on the frame 1 to prevent permanent 
deformation. 
The second embodiment of the present invention is described below referring 
to drawings. 
The above first embodiment cuts the sheet material only when the sheet 
material cutting mechanism moves in one direction. With the second 
embodiment, on the other hand, the sheet material is cut by both the 
forward and backward travel of the sheet material cutting mechanism. 
Like the first embodiment, the second embodiment also has a construction so 
that the sheet material cutting mechanism 30 travels along a screw shaft 2 
mounted on the frame 1. Like the first embodiment again, the frame 1 has a 
recess to prevent permanent deformation of the rubber roller (described 
later) when the device rests on either end of the frame 1. 
The structure of the sheet material cutting mechanism of the second 
embodiment is described below. 
FIG. 5 is a plan view of the sheet material cutting means. FIG. 6 is a 
sectional view of section C--C in FIG. 5. FIG. 7B is a plane view of the 
rotary blade supporting member and FIG. 7A is a cross-sectional view of 
section D--D in FIG. 7B. 
In the figure, frame 1 supports the screw shaft 2 at both ends as described 
before. The frame 1 and the screw shaft 2 have the same construction as 
that in the first embodiment. 
FIGS. 7A and 7B show the rotary blade supporting member 30a which is 
slidably mounted on the frame 1. 
In the figure, the rotary blade supporting member 30a comprises an 
integrally formed rotary blade supporting member 30a and a cover 30b which 
is fitted to said rotary blade supporting member 30a. The rotary blade 
supporting member 30a has a threaded portion 30c for engagement with the 
screw shaft 2, and a guide groove 30d to which the guide 6 of the frame is 
slidably mounted as shown in the figure. Sheet material guides 31, 31 are 
symmetrically formed in the horizontal direction. A bearing to hold the 
shaft 11 of the first rotary blade 10 is provided above (to the right in 
the figure) the guide groove 30d. The rotary blade supporting member 30a 
also provides a roller groove 33 to accommodate a roller 32 (described 
later). The roller 32, accommodated in the roller groove 33, is placed 
between the frame 1 and the first rotary blade 10; is in contact with the 
upper surface of the guide 6 of the frame and the back side of the first 
rotary blade; rotates the first rotary blade 10 by frictional force; and 
causes the first rotary blade to incline. 
The rotary blade supporting member 30a also provides a bearing 34 to 
support the second rotary blade 20. A cover 30b with a bearing hole 35 is 
mounted opposite to this. 
The first and the second rotary blades 10 and 20 are assembled into the 
rotary blade supporting member 30a with the above construction as shown in 
FIGS. 5 and 6. It is important in this instance that the cutting edge of 
the first and the second rotary blades 10 and 20 be exposed from the sheet 
material guide 31. 
In the assembled state, the first rotary blade 10 is pressed in the axial 
direction (to the left in FIG. 6) by a plate spring 16. The shaft 11 of 
the first rotary blade 10 is set loose so that it inclines to some extent 
with reference to the rotary blade supporting member 30a. A roller 32 is 
provided between the first rotary blade 10 and the frame 1. The roller 32 
is used to slightly incline the first rotary blade forward. The roller 32 
can move back and forth in the roller groove 33 toward the direction of 
movement of the rotary blade supporting member. Because of this mechanism, 
the first rotary blade 10 can be inclined forward while rotating (This 
mechanism is described in full detail in the Japanese Laid-Open Patent No. 
5-200694/1993 (U.S. Pat. No. 5,307,716). The detailed explanation is 
omitted here because the above mechanism and principle is used as is). 
The second rotary blade 20 and the rubber roller 22 are rotatably and 
slidably mounted on the shaft 21 of the second rotary blade 20 via a 
bearing 23. Further, said shaft 21 is supported by the rotary blade 
supporting member 30a and a cover 30b. The outside diameter of the rubber 
roller 22 is greater than that of the second rotary blade 20. This is 
necessary for the rubber roller 22 to firmly press, while being deformed, 
the sheet material to be cut against the surface 5 of the frame 1 when the 
sheet material cutting means 30 moves. The second rotary blade 20 and the 
rubber roller 22 are pressed to the right in FIG. 6 by a spring 24 as 
shown, with the result that the back side of the first rotary blade 10 and 
the upper side of the second rotary blade 20 come into contact with each 
other under appropriate pressure. In this embodiment, the rubber roller 22 
is integrally constructed with the second rotary blade 20, but these may 
be separate components. Further, the spring pressing the second rotary 
blade 20 may be different from what is shown in the figure; various other 
types of springs may be used provided the same function is achieved. 
The operation of the above sheet material cutting device with the above 
construction as the second embodiment is described below. 
In FIG. 5, when the sheet material cutting mechanism moves to the left, the 
roller 32 moves in the roller groove 33 until it hits the stopper in said 
roller groove, or comes to the position shown by the solid lines in FIG. 
5. By this motion of the roller 32, the first rotary blade 10 is supported 
by points P and Q. The rotary blade 10 is inclined forward by the rotation 
moment which is generated for the supporting axial line, with the result 
that the rotary blade 10 is pressed against the second rotary blade 20 at 
the contact point P. 
As the sheet material cutting mechanism 30 continues to move to the left in 
this state along the frame 1, the roller 32 rotates by the friction with 
the frame guide, and the first rotary blade 10 also rotates with the 
rotation of the roller 32. In this way, the rotary blade 10 rotates while 
the sheet material cutting mechanism 30 moves to the left, and the second 
rotary blade 20 also rotates by the frictional force between the rubber 
roller 22 and the frame. The first rotary blade 10 comes into contact with 
the second rotary blade while the former is inclined, and the sheet 
material, located between the first and the second rotary blades, is cut 
by the cooperation of the two blades. When the sheet material has been cut 
and the sheet material cutting mechanism 30 has moved to the extreme end 
of the screw shaft 2, the sheet material cutting mechanism 30 maintains 
its state until the next sheet material is fed. 
When the sheet material is supplied again, the screw shaft 2 rotates 
reversely by the motor (not shown). By this rotation, the sheet material 
cutting mechanism 30 starts to move in reverse, and cuts the sheet 
material in the same manner as described above. In this state, the first 
rotary blade 10 inclines in the reverse direction and moves while rotating 
in the direction of movement of the rotary blade supporting member while 
maintaining an appropriate degree of inclination in reference to the 
second rotary blade 20. 
In the second embodiment of the present invention as described above, the 
rotary blade supporting member can cut the sheet material by both its 
forward and backward movement along the screw shaft. Further, the first 
rotary blade can be inclined at an appropriate angle against the second 
rotary blade in accordance with the direction of movement of the rotary 
blade supporting member, thereby enhancing the efficiency of cutting of 
sheet materials and producing a very sharp cut. 
It is desirable to keep the back side of the first rotary blade, the roller 
surface, and that area of the surface of the frame 1 that is in contact 
with the roller in a state that is suitable for producing an adequate 
frictional force. 
In this embodiment as well, the motor is controlled so that the rotary 
blade supporting member is always located at either end of the frame 1 in 
the waiting state of the system. In the waiting state, the rubber roller 
rests on a recess formed on the frame 1 to prevent permanent deformation. 
The above second embodiment is the same as the first embodiment of the 
present invention in that (1) the inclination of the first rotary blade 
against the second rotary blade can be freely changed by changing the 
diameter of the roller 32, and (2) the sheet material cutting mechanism 30 
can travel along the screw shaft 2 both forward and backward without 
changing the direction of motor rotation because the screw shaft 2 has 
continuous right- and left-handed threads. 
The means to move the sheet material cutting mechanism back and forth is 
not limited to a screw shaft, but rather many other types such as belt and 
wire may be used. 
In the first and the second embodiments, the first rotary blade 10 comes 
into contact with the upper surface of the second rotary blade. The 
reverse construction may also be used, that is, the second rotary blade 20 
may come into contact with the upper surface of the first rotary blade. In 
this case, the direction of the springs for pressing the respective rotary 
blades is also reversed. 
The present invention may be implemented in various other forms of 
embodiment without deviating from the spirit of the main features thereof. 
The above-mentioned embodiments are therefore only a few examples and 
should not be construed as limiting. All variations and alterations 
falling under the scope of equivalents to the patent claims come under the 
scope of the present invention. 
As described in detail above, the sheet material cutting mechanism of the 
present invention cuts sheet material with a very simple construction 
comprising two rotary blades, and satisfactorily cuts a strip-shaped sheet 
material such as paper by simply inclining a circular rotary blade which 
is moving while rotating at the appropriate angle necessary for cutting. 
In addition, the sheet material cutting mechanism of the present invention 
does not use a fixed blade that requires attention to the wear of the 
cutting edge. Further, the two rotary blades rotate while maintaining 
contact with each other when cutting the sheet material, so that the 
rotary blades are always in the state of being ground, facilitating the 
maintenance of sharp cutting edges. Further, a rubber roller to press a 
sheet material is coaxially mounted on the shaft of one of the two rotary 
blades, so that the sheet material to be cut is pressed by said rubber 
roller immediately before the sheet material is cut to prevent lifting and 
bending of the sheet material when it is cut, assuring a sharp cut. The 
sheet material cutting mechanism of the present invention has these 
excellent functions.