Sheet orthogonal-conveying method and device

A sheet orthogonal-conveying method and apparatus in which the front edge of a sheet sliding under its own weight is delivered into the nip formed between a pair of rollers orthogonal to the direction of advancement of the sheet. The sheet is first guided so that its front edge slides into contact with the side edge of one of the rollers, preferably the upper one of the rollers, at a position away from the nip. After the sheet has reached a stationary position stopped by the roller, the position of the guide has changed so that the sheet may slide into the nip and be clamped and conveyed by the rollers. Preferably, the sheet is vibrated during this operation. An elastic guide piece may be utilized to urge the sheet toward a reference surface of the guide member.

BACKGROUND OF THE INVENTION 
The present invention relates to a method for conveying sheets in which a 
sheet guided upon sliding downward under its own weight is positioned with 
its front edge orthogonal to the direction of advancement of the sheet and 
is then conveyed with two opposed rollers or a pair of rollers. Such a 
method is hereinafter referred to as "a sheet orthogonal-conveying 
method". The invention also relates to a device for practicing the method, 
hereinafter referred to as "a sheet orthogonal-conveying device". 
An operation of conveying a sheet with a pair of rollers, the sheet sliding 
under its own weight, is used in releasing exposed X-ray picture film 
sheets from a cassette 1 as shown in FIG. 1. A released film sheet 2 
slides down a guide member 3 and its front edge is introduced between a 
pair of rollers 4 and 5. The film sheet 2 is then conveyed by rotation of 
the rollers 4 and 5 to the following process position such as for exposure 
printing with an ID card or developing. In this connection, it is 
desirable that the front edge of the film sheet 2 conveyed with the pair 
of rollers be orthogonal to the direction of advancement or conveyance of 
the sheet. This is essential for the case where the sheet is subjected to 
exposure printing with an ID card so that the image is printed at a 
predetermined position on the sheet. 
A conventional method for conveying a sheet which has slid under its own 
weight with a pair of rollers with the front edge of the sheet orthogonal 
to the direction of advancement of the sheet is such that the front edge 
of the sheet is made orthogonal with the direction of advancement of the 
sheet when it is stopped along the nip region of the two rollers. The 
sheet is conveyed by rotation of the rollers which is started following a 
time delay after the front edge has been brought into contact with the 
rollers. This method is an application of the technique described in the 
specification of Japanese Laid-Open patent application No. 112366/1974, 
for instance. 
However, the conventional method is disadvantageous in the following 
points. In the case where a sheet slides down at high speed or a sheet is 
thin and rigid to some extent, sometimes the sheet penetrates unevenly 
into the nip region of the rollers. That is, one of the right and left 
ends of the front edge of the sheet goes into the nip region more deeply 
than the other with the result that the front edge is not orthogonal with 
the direction of advancement of the sheet. 
In order to overcome this difficulty, a technique has been disclosed in 
Japanese Laid-Open patent application No. 79682/1977. With this technique, 
after the front edge of a sheet strikes against a pair of rollers, the 
rollers are turned in the opposite direction to prevent the front edge 
from going into the nip region of the rollers deeply and to set the front 
edge straightly along the nip region, that is, to make the front edge 
orthogonal to the direction of advancement of the sheet. Then the rollers 
are turned in the forward direction to convey the sheet. In this method, 
in the course of making the front edge of the sheet orthogonal to the 
direction of advancement of the sheet, sometimes the corners of the sheet 
are shifted along the nip region of the rollers in the wedge-shaped space 
of the nip region. Because of this, it takes a relatively long time to 
make the front edge orthogonal to the direction of advancement of the 
sheet because of frictional resistance which is caused when the corners of 
the sheet are shifted as described above. With a sheet curled to some 
extent, sometimes one of the ends of the front edge of the sheet goes 
further into the wedge-shaped space than the other and this state is 
maintained unchanged for a time with the result that the front edge of the 
sheet is immediately not made orthogonal to the direction of advancement 
of the sheet. 
Accordingly, an object of the invention is to provide a sheet 
orthogonal-conveying method in which the difficulty accompanying a 
conventional method that the front edge of a sheet sliding down under its 
own weight goes into the nip region of a pair of rollers deeply is 
eliminated and even a sheet curled to some extent can be conveyed with its 
front edge orthogonal to the direction of advancement of the sheet. 
SUMMARY OF THE INVENTION 
The foregoing object and other objects of the invention have been achieved 
by the provision of a method for orthogonally conveying sheets in which a 
sheet guided while sliding under its own weight is positioned with its 
front edge orthogonal to the direction of advancement of the sheet and is 
then conveyed with a pair of rollers, wherein, according to the invention, 
the front edge of the sheet is brought into contact with one of the pair 
of rollers so that the sheet stops at the one roller with the front edge 
thereof orthogonal to the direction of advancement of the sheet after 
which the front edge of the sheet is introduced between the pair of 
rollers. 
In accordance with the method of the invention, a sheet released from the 
cassette or delivered by a delivering mechanism to a position higher in 
level than the nip line of a pair of rollers so as to slide under its own 
weight is detained by one roller of the pair of rollers whereby the front 
edge of the sheet is set along the generating line of the cylindrical 
roller after which the sheet is introduced between the rollers. The roller 
for firstly receiving the sheet may be either the upper roller or the 
lower roller. The upper roller may be selected to allow the sheet with the 
front edge orthogonal to the direction of advancement of the sheet to 
further slide down under its own weight into the nip formed between the 
rollers and which the lower roller may be selected to introduce the sheet 
with the front edge orthogonal to the direction of advancement of the 
sheet between the rollers utilizing the rotation of the rollers. 
Additionally, the sheet may be vibrated or one side edge of the sheet may 
be depressed sidewardly with an elastic piece in combination with the 
above-described method so that the front edge of the sheet can be more 
effectively made orthogonal with the direction of advancement of the sheet 
.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The invention will be described with reference to FIGS. 2 through 8A. 
A first embodiment of a sheet orthogonal-conveying device constructed 
according to the invention is shown in FIG. 2. In the device, a guide 
member 3 is provided which is displaceable between a first position A 
indicated by solid lines and a second position B indicated by dashed 
lines. When the guide member 3 is at the position A, the front edge of a 
sheet 2 sliding down the guide member 3 comes into abutment with an upper 
roller 4 which is paired with a lower roller 5 and the sheet 2 is stopped 
by the upper roller 4. When the guide member is at the position B, the 
front edge of the sheet stopped by the upper roller is introduced between 
the pair of rollers 4 and 5. The guide member 3 is rotatably supported at 
a support point 6 and initially is set at the first position A. 
With this construction, the front edge of a sheet 2 sliding down the guide 
member 3 strikes the circumferential wall of the roller 4 and is then 
brought into contact with the generating line of the cylindrical roller 4. 
That is, the sheet 2 is stopped with its front edge orthogonal to the 
direction of advancement of the sheet. The time interval which elapses 
from the time instant that the front edge of the sheet 2 strikes the 
roller 4 until the sheet 2 is stopped with its front edge orthogonal to 
the direction of advancement of the sheet is of the order of 0.5 to 3 
seconds. After the sheet 2 is stopped, the guide member 3 is turned to the 
second position B. As a result, the sheet 2 is allowed to slide down again 
and the front edge of the sheet 2 is introduced between the rollers 4 and 
5. The speed of the sheet sliding down the guide member 3 at this time is 
low and therefore the sheet will not slide into the nip region of the 
rollers 4 and 5. As the front edge of the sheet 2 is brought into contact 
with the nip region, the sheet 2 is set with its front edge forming a 
right angle with the sheet advancement direction. When the sheet is in 
this position, the rollers 4 and 5 are turned to convey the sheet. The 
sheet will not be inclined during the period that the sheet is stopped at 
the roller 4 with its front edge orthogonal to the sheet advancement 
direction. 
The rollers 4 and 5 may be maintained rotated throughout the operation. In 
this case, in order that the sheet 2 is not conveyed by the rotation of 
the roller 4 when its front edge is in contact with the roller 4, it is 
necessary to make the distance between the guide member 3 and the roller 
sufficiently small or the position A should be so selected that the angle 
formed by the guide surface of the guide member 3 and the cylindrical wall 
of the roller 4 is not small. In the case where the pair of rollers are 
rotating throughout the operation, the sheet 2 is allowed to further slide 
down upon displacement of the guide member 3 to the second position B from 
the first position A. Its front edge is then brought into contact with the 
rotating roller 5. It should be noted that the front edge is uniformly 
brought into contact with the roller 5 in the axial direction of the 
roller because it is oriented orthogonal to the sheet advancement 
direction and therefore the sheet will not be inclined. The device may be 
so designed that first the rollers 4 and 5 stop then start rotation again 
when the guide member 3 is shifted from the first position A to the second 
position B. 
A second embodiment of a device constructed according to the invention is 
shown in FIG. 3. In this embodiment, the guide member 3 is shifted between 
a first position C indicated by the solid line and a second position B. 
When the guide member 3 is at the first position C, the front edge of a 
sheet 2 sliding down the guide member comes into contact with a lower 
roller 5 which is paired with an upper roller 4 and the sheet 2 is 
detained by the lower roller 5. When the guide member 3 is at the second 
position B, the front edge of the sheet 2 is introduced between the 
rollers 4 and 5. 
When the guide member 3 is at the first position C, the front edge of the 
sheet sliding down the guide member 3 strikes the generating line of the 
cylindrical lower roller 5 whereby the sheet is stopped with its front 
edge orthogonal to the sheet advancement direction. Therefore, the guide 
member 3 is shifted to the second position B. As a result, the front edge 
of the sheet 2 is shifted along the surface of the roller 5 and therefore 
the sheet is allowed to slide further. Finally, the front edge of the 
sheet 2 is guided into the nip between the rollers 4 and 5. The operation 
after this is the same as that in the first embodiment shown in FIG. 2. If 
the pair of rollers 4 and 5 are maintained rotating, in order that the 
sheet 2 is not conveyed by the rotation of the roller 5 when it is brought 
into contact with the roller 5, the first position C should be so selected 
that the guide surface of the guide member 3 and the circumferential wall 
of the roller 5 form a small angle or a limiting guide member 7 should be 
provided above the guide member 3 as shown in FIG. 4 with the limiting 
guide member 7 shifted with the guide member 3. 
A third embodiment of a device constructed according to the invention as 
shown in FIG. 5 includes a guide member 3 for guiding a sheet sliding 
under its own weight so that the front edge of the sheet is brought into 
contact with a lower roller 5 which is paired with an upper roller 4 to 
stop the sheet 2. A limiting guide member 7 is provided above the guide 
member 3 which is retractable to a position D indicated by dashed lines. 
The front edge of the sheet sliding down the guide member 3 is brought into 
contact with the roller 5 and the sheet 2 is stopped with its front edge 
orthogonal to the sheet advancement direction. Thereafter, the limiting 
guide member 7 is shifted to the position D. As a result, the sheet 2 
falls into the nip formed between the rollers 4 and 5 and is advanced by 
rotation of the rollers 4 and 5. The rollers 4 and 5 may be maintained 
rotating. Alternatively, the device may be so designed that first the 
rollers 4 and 5 are stopped then started again after the limiting guide 
member 7 has been retracted to the position D. 
FIG. 6 shows a fourth embodiment of a device according to the invention. 
The fourth embodiment includes a guide member 3 for guiding a sheet 2 so 
that its front edge is brought into contact with an upper roller 4 which 
is paired with a lower roller 5 to stop the sheet 2 and a guide member 8 
for guiding the sheet 2 so that the front edge thereof is clamped by the 
rollers 4 and 5. The guide member 3 is retracted to a position E indicated 
by dashed lines so that the sheet 2 is transferred to the guide member 
after the front edge of the sheet 2 sliding down the guide member 3 is 
brought into contact with the upper roller 4 to stop the sheet. The guide 
members 3 and 8 are each in the form of a comb so that they can cross each 
other. When the guide member 3 is retracted to the position E, the sheet 2 
brought into contact with the roller 4 with the front edge of the sheet 
orthogonal to the sheet advancement direction is dropped onto or 
transferred to the guide member 8 from the guide member 3. 
In the above-described embodiments of devices constructed according to the 
invention, the sheet may be vibrated with a vibrator of a type disclosed, 
for example, in the specification of Japanese Laid-Open Utility Model 
Applications Nos. 149671/1977, 53774/1978 and 31681/1979. Vibration is 
applied to the sheet 2, for instance, by a vibrator 11 attached to the 
guide member 3 as shown in FIG. 5, before the sheet 2 is brought into 
contact with one of the pair of rollers 4 and 5 with its front edge 
orthogonal to the sheet advancement direction. Alternatively, the sheet 2 
may be vibrated while the sheet 2 is being introduced between stopped 
rollers 4 and 5 with the front edge lying along the nip region of the 
rollers 4 and 5. 
FIGS. 7A and 7B and FIGS. 8A and 8B show a fifth embodiment of a device 
according to the invention which utilizes a technique disclosed by 
Japanese Utility Model Application No. 87778/1979 filed by the present 
applicant. 
In the fifth embodiment of the invention, the technique of the first 
embodiment shown in FIG. 2 is employed and an elastic piece 9 is provided 
so as to shift one side edge of a sheet 2 on the guide member 3 to a 
reference side 10 provided on the guide member whereby the sheet 2 is set 
with its front egde orthogonal to the sheet advancement direction and 
simultaneously the sheet 2 is positioned correctly in its lateral 
direction. In this embodiment, the sheet 2 may also be vibrated with a 
vibrator. 
A biasing force should be applied to the elastic piece 9 for shifting a 
sheet 2 to the reference side 10. If the sheet is moved between the 
rollers 4 and 5 after the front edge of the sheet 2 has been brought into 
contact with the roller 4 to stop the sheet 2 with the front edge 
orthogonal to the sheet advancement direction and if the size of the sheet 
2 is relatively small and hence the frictional force of the elastic piece 
9 is larger than the energy of advancing the sheet, it is difficult for 
the sheet 2 to advance. Accordingly, the device should be so designed that 
the elastic piece 9 is in contact with the sheet 2 only when the guide 
member 3 is at the first position A and the elastic piece 9 is disengaged 
from the sheet 2 when the guide member is shifted to the second position 
B. FIGS. 7A and 7B shows a state of the device in which the guide member 3 
is disposed at the first position A. With this structure, the sheet 2 
slides down the guide member while being positioned in its lateral 
direction so that one side edge thereof is held in contact with the 
reference side 10 by a force applied by the elastic piece 9. As a result, 
the front edge of the sheet is brought into contact with the roller 4 to 
stop the sheet 2 with the front edge orthogonal to the sheet advancement 
direction. In this operation, the front edge will more quickly be made 
orthogonal if vibration is also applied. 
Thereafter, the guide member 3 is shifted to the second position B as shown 
in FIGS. 8A and 8B. Upon shifting of the guide member 3 to the second 
position, the sheet 2 is lowered with the guide member 3 away from the 
elastic piece 9 and therefore the sheet 2 is advanced and introduced into 
the nip formed between the rollers 4 and 5. 
In the embodiments of the device shown in FIGS. 2 through 8B, displacement 
of the guide member or the limiting guide member and rotation of the 
rollers can be achieved with a conventional drive structure in which the 
position of the sheet is detected in a conventional manner. For instance, 
the device may be so designed that the front edge of a sheet sliding down 
the guide member is detected with a limit switch or a photoelectric 
detecting device and the relevant mechanisms are operated with 
predetermined time delays after detection. 
In the sheet orthogonal-conveying method of the invention, as described 
above, a sheet sliding down under its own weight is introduced between a 
pair of rollers after the front edge of the sheet has been brought into 
contact with one of the rollers to stop the sheet with the front edge 
thereof orthogonal to the sheet advancement direction. Therefore, the 
difficulty accompanying the conventional method that the front edge of a 
sheet sliding under its own weight goes directly into the nip of the 
rollers is eliminated with the use of the invention. In accordance with 
the method of the invention, the front edge of a sheet is oriented 
orthogonal to the sheet advancement direction before it is introduced 
between the pair of rollers. Therefore, even a sheet curled to some extent 
can be oriented with the front edge orthogonal to the sheet advancement 
direction.