U.S. patent application number 12/893504 was filed with the patent office on 2011-04-07 for printing apparatus.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Katsunori ONO, Koichi SAITO, Akio TODORIKI.
Application Number | 20110079952 12/893504 |
Document ID | / |
Family ID | 43822593 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110079952 |
Kind Code |
A1 |
ONO; Katsunori ; et
al. |
April 7, 2011 |
PRINTING APPARATUS
Abstract
A printing apparatus includes a transporting roller formed of a
metal plate bent into a cylindrical shape. The transporting roller
has a first driving member that transmits a rotational driving
force to the transporting roller, and a second driving member that
transmits the rotational driving force transmitted thereto to a
processing unit that performs printing-related processing. The
first and second driving members are provided on one end side of a
transporting area where recording media are transported.
Inventors: |
ONO; Katsunori;
(Shiojiri-shi, JP) ; SAITO; Koichi;
(Matsumoto-shi, JP) ; TODORIKI; Akio;
(Azumino-shi, JP) |
Assignee: |
SEIKO EPSON CORPORATION
Tokyo
JP
|
Family ID: |
43822593 |
Appl. No.: |
12/893504 |
Filed: |
September 29, 2010 |
Current U.S.
Class: |
271/10.09 |
Current CPC
Class: |
B41J 13/076 20130101;
B41J 13/03 20130101 |
Class at
Publication: |
271/10.09 |
International
Class: |
B65H 5/06 20060101
B65H005/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2009 |
JP |
2009-230373 |
Claims
1. A printing apparatus comprising a transporting roller formed of
a metal plate bent into a cylindrical shape, wherein the
transporting roller has a first driving member that transmits a
rotational driving force to the transporting roller, and a second
driving member that transmits the rotational driving force
transmitted thereto to a processing unit that performs
printing-related processing, the first and second driving members
being provided on one end side of a transporting area where
recording media are transported.
2. The printing apparatus according to claim 1, wherein the
processing unit operates while the recording media are
transported.
3. The printing apparatus according to claim 1, wherein a seam of
the metal plate constituting the transporting roller includes an
intermediate straight portion that is located in the transporting
area and is formed linearly in the axial direction, and a crossing
portion that is located on one end side of the transporting area
and is formed by fitting a recess and a projection provided at the
end surfaces of the metal plate around the axis so as to extend in
a direction intersecting the axial direction.
4. The printing apparatus according to claim 1, wherein a third
driving member is provided on the other end side of the
transporting area of the transporting roller, the third driving
member transmitting a rotational driving force transmitted thereto
to a second processing unit for performing printing-related
processing, which does not operate while the recording media are
transported.
5. The printing apparatus according to claim 4, wherein the seam of
the metal plate constituting the transporting roller includes an
intermediate straight portion that is located in the transporting
area and is formed linearly in the axial direction, and a second
crossing portion that is located on the other end side of the
transporting area and is formed by fitting a recess and a
projection provided at the end surfaces of the metal plate around
the axis so as to extend in a direction intersecting the axial
direction.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to printing apparatuses.
[0003] 2. Related Art
[0004] There are printing apparatuses for recording information on
sheet-like recording media. Such printing apparatuses have a
transportation unit for transporting the recording media. The
transportation unit includes a transporting roller that rotates to
transport the recording media.
[0005] The transporting roller has a driving member such as a gear
for rotating the transporting roller or for driving another device
by the rotation of the transporting roller.
[0006] In general, a solid rod-like member is used as the
transporting roller. However, because a solid material is heavy,
the roller deflects under its own weight, degrading the printing
precision. JP-A-2006-289496 discloses a technique for forming a
metal plate into a cylindrical shape by bending.
[0007] However, if the cylindrical shaft disclosed in
JP-A-2006-289496 is used as the transporting roller, the following
problems occur.
[0008] For example, when a rotational driving force from a motor or
the like transmitted to the transporting roller is used to drive
another device via a driving member, slip due to the torque acting
on the transporting roller occurs at the seam created when the
metal plate is formed in a cylindrical shape. This degrades the
roundness or the like, significantly decreasing the transportation
precision, for example, the recording media are transported in a
skewed manner. As a result, there has been a problem of degradation
in printing precision.
SUMMARY
[0009] An advantage of some aspects of the invention is that it
provides a printing apparatus that can suppress degradation in
transportation precision.
[0010] According to an aspect of the invention, a printing
apparatus includes a transporting roller formed of a metal plate
bent into a cylindrical shape. The transporting roller has a first
driving member that transmits a rotational driving force to the
transporting roller, and a second driving member that transmits the
rotational driving force transmitted thereto to a processing unit
that performs printing-related processing. The first and second
driving members are provided on one end side of a transporting area
where recording media are transported.
[0011] In the printing apparatus according to an aspect of the
invention, because the first driving member and the second driving
member that apply torque to the transporting roller are provided on
one end side of the transporting area, the transporting area of the
transporting roller is not subjected to a large torque.
Accordingly, it is possible to suppress degradation in
transportation precision and printing precision due to slip at a
seam in the transporting area of the transporting roller.
[0012] The processing unit may operate while the recording media
are transported.
[0013] Thus, according to an aspect of the invention, even when the
second driving member performs processing while the recording media
are transported, the transporting area of the transporting roller
is not subjected to a large torque. Thus, degradation in
transportation precision can be suppressed.
[0014] A seam of the metal plate of the transporting roller may
include an intermediate straight portion that is located in the
transporting area and is formed linearly in the axial direction,
and a crossing portion that is located on one end side of the
transporting area and is formed by fitting a recess and a
projection provided at the end surfaces of the metal plate around
the axis so as to extend in a direction intersecting the axial
direction.
[0015] Thus, according to an aspect of the invention, because the
length of the seam in the transporting area can be minimized,
degradation in transportation precision and printing precision due
to the seam can be suppressed. Furthermore, according to an aspect
of the invention, the seam includes a crossing portion extending in
a direction intersecting the axial direction on one end side of the
transporting area, where the first driving member and the second
driving member are provided. Thus, it is possible to prevent the
seam from slipping in the axial direction. Accordingly, even when a
large torque is applied to the transporting roller via the first
driving member and the second driving member, deformation of the
transporting roller can be suppressed. Thus, degradation in
transportation precision of the transporting roller due to
deformation can be suppressed.
[0016] Furthermore, a third driving member may be provided on the
other end side of the transporting area of the transporting roller,
the third driving member transmitting a rotational driving force
transmitted thereto to a second processing unit for performing
printing-related processing, which does not operate while the
recording media are transported.
[0017] Thus, according to an aspect of the invention, it is
possible to transmit the rotational driving force to a second
processing unit that is different from the second driving member to
perform the printing-related processing. Because the second
processing unit does not operate while the recording media are
transported, it does not affect the recording-media transportation
precision.
[0018] Furthermore, in the above-described configuration, the seam
of the metal plate constituting the transporting roller may include
an intermediate straight portion that is located in the
transporting area and is formed linearly in the axial direction,
and a second crossing portion that is located on the other end side
of the transporting area and is formed by fitting a recess and a
projection provided at the end surfaces of the metal plate around
the axis so as to extend in a direction intersecting the axial
direction.
[0019] Thus, according to an aspect of the invention, it is
possible to suppress deformation of the transporting roller on the
other end side of the transporting area while suppressing
degradation in transportation precision and printing precision due
to the seam. Thus, degradation in transportation precision of the
transporting roller due to deformation can be suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0021] FIG. 1 is a side sectional view of a printer of the
invention.
[0022] FIG. 2A is a plan view schematically showing the
configuration of a transporting portion and a sheet-discharging
portion, and FIG. 2B is a view from the direction of arrow IIB.
[0023] FIG. 3 is a schematic diagram of the configuration of a
transporting roller mechanism.
[0024] FIG. 4 is an external perspective view of a roller body.
[0025] FIG. 5 is a plan view of a metal plate serving as the base
material of the roller body.
[0026] FIG. 6A is a perspective view of the relevant part of the
roller body, and FIG. 6B is a side sectional view of the relevant
part.
[0027] FIGS. 7A to 7C show the process of pressing the metal
plate.
[0028] FIGS. 8A to 8C show the process of pressing the metal
plate.
[0029] FIGS. 9A to 9C show other shapes of a seam.
[0030] FIGS. 10A and 10B are a perspective view and a side view of
the relevant part of the roller body, respectively.
[0031] FIGS. 11A and 11B are a perspective view and a side view of
the relevant part of the roller body, respectively.
[0032] FIGS. 12A and 12B are a perspective view and a side view of
the relevant part of the roller body, respectively.
[0033] FIGS. 13A to 13C are plan views of the relevant part of the
metal plate, showing unfolded engaging portions.
[0034] FIG. 14 is an enlarged view of the seam of the roller body
and the vicinity thereof.
[0035] FIG. 15A is a plan view showing the transporting roller,
FIG. 15B is a sectional view showing the seam, FIG. 15C is a
sectional view showing an opening, and FIG. 15D is a diagram
showing a modification of the opening.
[0036] FIG. 16 is a schematic diagram showing an example of the
configuration of the transporting roller.
[0037] FIG. 17 is a schematic diagram showing an example of the
configuration of the transporting roller.
[0038] FIG. 18 is a sectional view of the metal plate after end
surfaces thereof are adjusted.
[0039] FIGS. 19A and 19B show a punching process according to an
embodiment.
[0040] FIGS. 20A to 20C are plan views of the relevant part of the
metal plate, showing unfolded engaging portions.
[0041] FIGS. 21A and 21C show the seam, and FIG. 21B is a plan view
of the metal plate.
[0042] FIG. 22 is a perspective view showing the relationship
between the transporting roller and a sheet during sheet
feeding.
[0043] FIGS. 23A to 23C show the shapes of the seam.
[0044] FIG. 24A shows the shape of the seam, and 24B shows the
operation thereof.
[0045] FIG. 25 shows the shape of the seam.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0046] Referring to FIGS. 1 to 25, a printing apparatus according
to an embodiment of the invention will be described below.
[0047] Note that the following embodiment shows merely an aspect of
the invention and does not limit the invention. It may be modified
appropriately within the technical scope of the invention. In the
attached drawings, the scale, number, etc., of the structures are
different from those of the actual structures for clarity's
sake.
[0048] First, the configuration of a printer (printing apparatus) 1
according to this embodiment will be described with reference to
FIG. 1.
[0049] FIG. 1 is a diagram of the overall configuration of the
printer 1 according to this embodiment.
[0050] The printer 1 is a printing apparatus that ejects ink onto
paper, serving as a recording medium, to record information such as
characters and images. The printer 1 includes a sheet-feed portion
2, a transporting portion (transportation unit) 3, a
sheet-discharging portion 4, a head portion 5, and a control unit
CONT.
[0051] The sheet-feed portion 2 holds a plurality of recording
sheets (sheet materials) P, serving as recording media, and feeds
the recording sheets P to the transporting portion 3. The
sheet-feed portion 2 includes a sheet-feed tray 21 and a sheet-feed
roller 22.
[0052] The sheet-feed tray 21 holds a plurality of recording sheets
P and is provided at a predetermined angle (about 45.degree.) with
respect to the horizontal plane. The recording sheets P are
sheet-like recording media on which printing with ink can be
performed. Examples of the recording sheets P include normal paper,
coated paper, sheets for overhead projectors (OHPs), glossy paper,
glossy films, etc.
[0053] The sheet-feed roller 22 is a roller that rotates to feed
the recording sheets P to the transporting portion 3. The
sheet-feed roller 22 is provided on the sheet-feed tray 21, at the
transporting portion 3 side. A separation pad (not shown) is
provided at a position facing the outer peripheral surface of the
sheet-feed roller 22, enabling the recording sheets P to be fed one
by one to the transporting portion 3 by the cooperation of the
separation pad and the sheet-feed roller 22.
[0054] The transporting portion 3 transports the recording sheets P
fed from the sheet-feed portion 2 to the sheet-discharging portion
4. Printing on the recording sheets P is performed at the
transporting portion 3. The transporting portion 3 includes a
transporting roller (cylindrical shaft) 31, driven rollers 32, a
platen 33, diamond ribs 34, and a driving unit 6 (see FIG. 2).
[0055] The transporting roller 31 rotates to precisely transport
the recording sheets P to a predetermined printing position. The
transporting roller 31 is a cylindrical shaft that is formed in a
substantially cylindrical shape and extends in the horizontal plane
and in the direction perpendicular to the transporting direction of
the recording sheets P. The transporting roller 31 is supported in
a rotatable manner by a pair of substantially U-shaped bearings
(not shown) provided on the transporting portion 3 and is rotated
by being driven by the driving unit 6. Details of the transporting
roller 31 will be described below.
[0056] The driven rollers 32 are substantially cylindrical members
that are arranged at intervals in the axial direction of the
transporting roller 31. As will be described below, the driven
rollers 32 are provided in a rotatable manner at a position facing
a high-friction layer (described below) of the transporting roller
31 (see FIG. 3). The driven rollers 32 have urging springs (not
shown). The driven rollers 32 are urged against the high-friction
layer 50 of the transporting roller 31 by the urging force exerted
by the urging springs. Thus, the driven rollers 32 are rotated by
the rotation of the transporting roller 31. The outer peripheral
surfaces of the driven rollers 32 are provided with wear-resistant
treatment, e.g., fluorocarbon resin coating, so that wear and
damage caused by sliding contact with the high-friction layer 50
are reduced.
[0057] The platen 33 supports the recording sheet P from below when
the head portion 5 performs printing on the recording sheet P and
has a top surface substantially parallel to the horizontal
plane.
[0058] The diamond ribs 34 are projections that protrude upward
from the top surface of the platen 33 and are arranged at intervals
in the axial direction of the transporting roller 31. Furthermore,
the top surfaces of the diamond ribs 34 are substantially parallel
to the horizontal plane and support the recording sheet P from
below during printing.
[0059] The sheet-discharging portion 4 includes a sheet-discharging
roller 41 and a sheet-discharge serrated roller 42 and discharges
the recording sheet P after printing from the transporting portion
3. The sheet-discharging roller 41 and the sheet-discharge serrated
roller 42 can rotate in opposite directions, thereby drawing and
discharging the recording sheet P.
[0060] The head portion 5 includes an ejection head 51 and a
carriage 52 and ejects ink onto the recording sheet P placed on the
transporting portion 3.
[0061] The ejection head 51 ejects ink according to the instruction
of the control unit CONT, and ejection ports (not shown) of the
ejection head 51 are provided to face the top surfaces of the
diamond ribs 34. The carriage 52 has the ejection head 51 at the
bottom thereof and can reciprocate in the axial direction of the
transporting roller 31. Furthermore, the carriage 52 is connected
to a driving unit (not shown) that reciprocates the carriage 52
according to the instruction of the control unit CONT.
[0062] Next, the configuration for rotationally driving the
transporting roller 31 will be described with reference to FIG.
2.
[0063] FIG. 2A is a plan view schematically showing the
configuration of the transporting portion 3 and the
sheet-discharging portion 4, and FIG. 2B is a view from the
direction of arrow IIB.
[0064] As described above, the transporting portion 3 includes the
driving unit 6. The driving unit 6 rotationally drives the
transporting roller 31 and includes a motor 61 and a pinion gear
62.
[0065] The motor 61 is a motor that rotates the transporting roller
31 according to the instruction of the control unit CONT. That is,
the control unit CONT controls and drives the motor 61 to achieve
rotation of the transporting roller 31 and accurate transportation
of the recording sheet P. The pinion gear 62 is connected to the
output shaft of the motor 61.
[0066] The transporting roller 31A has a first driving gear (first
driving member) 35 and a second driving gear (second driving
member) 36 that are provided on one end side (the left side in FIG.
2A), in the lengthwise direction (axial direction), of a
transporting area CA (see FIG. 3) that comes into contact with the
recording sheet P to transport the recording sheet P, and a third
driving gear (third driving member) 37 that is provided on the
other end side (the right side in FIG. 2A) of the transporting area
CA.
[0067] The first driving gear 35 is a gear that rotates the
transporting roller 31. The first driving gear 35 is connected to
an end of the transporting roller 31 on the driving unit 6 side by
press fitting. The first driving gear 35 and the pinion gear 62 are
meshed with each other, whereby the driving force of the motor 61
is transmitted to the transporting roller 31 via the pinion gear 62
and the first driving gear 35, rotating the transporting roller
31.
[0068] The second driving gear 36 is a gear that transmits the
driving force of the motor 61 to the sheet-discharging roller 41
serving as a processing unit. The second driving gear 36 has a
smaller diameter than the first driving gear 35 and is disposed
adjacent to and coaxially with the first driving gear 35.
[0069] The third driving gear 37 transmits the rotational driving
force of the transporting roller 31 to another device (a second
processing unit) 38, e.g., a pump that covers the nozzles in the
ejection head 51 (capping) to perform suction. More specifically,
the rotational driving force is transmitted via the third driving
gear 37 to a device that does not operate while the transporting
roller 31 transports the recording sheet P.
[0070] A method for connecting the second driving gear 36 and the
third driving gear 37 to the transporting roller 31 will be
described below.
[0071] The sheet-discharging roller 41 has a sheet-discharge
driving gear 43 provided at an end on the driving unit 6 side.
Furthermore, an intermediate gear 44 is provided between the
sheet-discharge driving gear 43 and the second driving gear 36. The
intermediate gear 44 is meshed with both the second driving gear 36
and the sheet-discharge driving gear 43. That is, the driving force
of the motor 61 is transmitted to the sheet-discharging roller 41
via the second driving gear 36, the intermediate gear 44, and the
sheet-discharge driving gear 43. Thus, rotation of the
sheet-discharging roller 41 causes sheet-discharge processing,
which is printing-related processing, to be performed.
[0072] FIG. 3 is a schematic diagram of the configuration of a
transporting roller mechanism 19 formed of the transporting roller
31 and the driven rollers 32.
[0073] The transporting roller 31 includes a roller body 16 formed
of a metal plate, such as a galvanized steel sheet or a stainless
steel sheet, that is formed into a cylindrical shape by pressing,
and the high-friction layer 50 provided on the surface of the
roller body 16. The high-friction layer 50 has the same length as
the transporting area CA corresponding to the recording sheet P
having the maximum width that can be printed by the printer 1 and
has a resin layer formed of, for example, epoxy resin or polyester
resin, and ceramic particles dispersed on the surface of the resin
layer. Examples of the ceramic particles include aluminum oxide
(alumina), silicon carbide, and silicon dioxide. The particle
diameter of the ceramic particles is adjusted by trituration. By
using trituration, the ceramic particles have relatively sharp
ends.
[0074] Furthermore, the ends of the transporting roller 31 are held
by bearings 70 so as to be rotatable. The roller body (cylindrical
shaft) 16 is formed in a cylindrical shape by pressing a metal
plate and bringing opposed ends (end surfaces) toward or into
contact with each other. Therefore, the roller body 16 has a seam
formed between the ends. In this embodiment, the configuration of
the seam near the transporting area CA differs from that at both
ends.
[0075] More specifically, as shown in FIG. 4, a seam 80 according
to this embodiment includes an intermediate straight portion 86
formed in the middle portion of the roller body 16 including the
transporting area CA and winding portions 85 formed at both ends of
the roller body 16. The above-described high-friction layer 50 is
formed on the intermediate straight portion 86. The intermediate
straight portion 86 is formed by bending a substantially
rectangular metal plate 60 in plan view, as shown in FIG. 5, into a
cylindrical shape and connecting together ends (end surfaces) 61a
and 61b, positioned at the middle portion in the lengthwise
direction, of the metal plate 60. Furthermore, the winding portions
85 positioned at both ends of the metal plate 60 in the lengthwise
direction have rectangular projections 61c protruding from the end
surface 61a in the widthwise direction (the peripheral direction
around a central axis 16a when formed in a cylindrical shape) and
rectangular recesses 61d recessed from the end surface 61b in the
widthwise direction (the peripheral direction around a central axis
16a when formed in a cylindrical shape). The rectangular
projections 61c and the rectangular recesses 61d have the same
widths and are arranged along the central axis 16a at a constant
pitch. As shown in FIG. 4, the winding portions 85 including
crossing portions 85a and crossing portions (second crossing
portions) 85b that extend in a direction crossing the central axis
16a are formed into a zigzag shape from staggered portions 110 that
fit together when the metal plate 60 is formed in a cylindrical
shape.
[0076] Furthermore, as shown in FIG. 6A, an engaging hole 71 for
connecting to the second driving gear 36 shown in FIG. 2 is
provided on one end side of the roller body 16 (transporting roller
31), at a position distant from the seam 80. More specifically, the
engaging hole 71 in the roller body 16 includes through-holes 71a
and 71a provided at positions facing each other, i.e., in the
surfaces having two points that define the diameter of the roller
body 16. Thus, the engaging hole (engaging portion) 71 including
these through-holes 71a and 71a can be formed. As shown in FIG. 6B,
by engaging the second driving gear 36 with the engaging hole 71
using a shaft or a pin (not shown), the second driving gear 36 can
be fixed to the roller body 16.
[0077] Although not shown in FIG. 6A, the roller body 16
(transporting roller 31) has an engaging hole 72 provided on the
other end side, at a position distant from the seam 80. As shown in
FIG. 6B, by engaging the third driving gear 37 with the engaging
hole 72 using a shaft or a pin (not shown), the third driving gear
37 can be fixed to the roller body 16.
[0078] The seam 80 is not shown in FIGS. 6A and 6B.
[0079] As a detailed description of the transporting roller 31, a
method for producing the transporting roller 31 will be described
with reference to FIGS. 5, 7, and 8.
[0080] In order to form the transporting roller 31, first, a
rectangular plate-like or strip-like large metal plate is prepared.
For example, a galvanized steel sheet having a thickness of about 1
mm is used as the large metal plate. Then, the large metal plate is
cut by pressing to form a long, narrow, substantially rectangular
plate-like metal plate 60 having a size corresponding to the size
of the roller body 16, i.e., the metal plate 60 serving as the base
material of the roller body 16, as shown in FIG. 5.
[0081] When the large metal plate is pressed and cut, in order to
form the winding portions at the seam between the ends, the
rectangular-wave-like staggered portions 110 are formed at both
ends in the lengthwise direction of the ends 61a and 61b, which are
the long sides facing each other. Furthermore, straight portions
111 are formed between the staggered portions 110 formed at both
ends of the long sides (ends).
[0082] Because the long sides (the ends 61a and 61b) are brought
toward or into contact with each other by pressing, the projections
of the staggered portion 110 of one long side, of course,
correspond to the recesses of the staggered portion 110 of the
other long side, and the recesses of the staggered portion 110 of
one long side correspond to the projections of the staggered
portion 110 of the other long side.
[0083] Next, as shown in FIGS. 7A to 7C and 8A to 8C, the metal
plate 60 is pressed into a cylindrical (pipe-like) shape so that
the ends 61a and 61b on both sides (on the long-side sides) are
brought toward or into contact with each other.
[0084] First, the metal plate 60 is pressed with a male mold 101
and a female mold 102, as shown in FIG. 7A, to bend both sides 62a
and 62b of the metal plate 60 in an arch shape (substantially 1/4
arch is desirable). Although 7A to 7C and 8A to 8C show spaces
between the metal plate 60, the male mold 101, and the female mold
102 for clarity's sake, there are no such spaces in actuality, and
the metal plate 60, the male mold 101, and the female mold 102 are
in tight contact with one another at their contact portions.
[0085] Next, using the male mold 103 and the female mold 104 shown
in FIG. 7B, the middle portion of the metal plate 60 shown in FIG.
7A in the widthwise direction (bending direction) is pressed and
bent into an arch shape (substantially 1/4 arch is desirable).
[0086] Then, as shown in FIG. 7C, a core mold 105 is disposed
inside the metal plate 60 shown in FIG. 7B. Using an upper mold 106
and a lower mold 107 shown in FIG. 7C, the end surfaces (ends) 61a
and 61b of the both sides 62a and 62b of the metal plate 60 are
brought toward each other, as shown in FIGS. 8A to 8C.
[0087] Herein, the outside diameter of the core mold 105 shown in
FIGS. 7C and 8A to 8C is the same as the inside diameter of the
cylindrical hollow pipe being formed. Furthermore, the radii of a
press surface 106c of the upper mold 106 and a press surface 107a
of the lower mold 107 are the same as the outside radius of the
hollow pipe being formed. Furthermore, as shown in FIGS. 8A to 8C,
the upper mold 106 includes a pair of left and right mold segments,
and these mold segments 106a and 106b can be individually raised
and lowered.
[0088] From the state shown in FIG. 7C, the upper mold segment 106a
on the right side is lowered relative to the lower mold 107
(hereinafter, the movement of the mold is relative movement), as
shown in FIG. 8A, to press and bend one side of the metal plate 60
in a substantially semicircular shape. Similarly to the upper mold
106, the lower mold 107 may include a pair of left and right mold
segments (see a segment surface 107b), and the lower mold segment
on the same side may be raised in the process shown in FIG. 8A.
[0089] Next, as shown in FIG. 8B, the core mold 105 is slightly
lowered (to such an extent that the ends 61a and 61b can be brought
toward each other), and the upper mold segment 106b on the other
side is lowered to press and bend the other side of the metal plate
60 in a substantially semicircular shape.
[0090] Then, as shown in FIG. 8C, the core mold 105 and the upper
mold segments 106a and 106b are lowered, forming a cylindrical
hollow pipe (roller body 16). In this state, the left end 61a and
the right end 61b are in contact with each other. That is, by
bringing the ends 61a and 61b of the metal plate 60, serving as the
base material, into contact with each other, a seam formed between
the ends 61a and 61b of the cylindrical hollow pipe.
[0091] Next, in this embodiment, the outer peripheral surface of
the hollow pipe (roller body 16) is ground by known centerless
grinding to increase the roundness of the hollow pipe (roller body
16) and to reduce runout.
[0092] As a result, the roundness of the hollow pipe becomes higher
than that before centerless grinding, reducing runout of the roller
body 16. Furthermore, because the distance between the ends 61a and
61b of the roller body (cylindrical shaft) 16 is further reduced,
the seam 80 with a reduced distance between the ends 61a and 61b is
formed.
[0093] When the staggered portions 110 shown in FIG. 5 fit
together, the winding portions 85 having the crossing portions 85a
and 85b are formed at both ends of the roller body 16, as shown in
FIG. 4.
[0094] Once the roller body 16 is formed, the high-friction layer
50 is formed on the surface of the roller body 16.
[0095] Although either a dry process or a wet process (or
combination of these methods) may be used to form the high-friction
layer 50, a dry process is preferably employed.
[0096] Next, the operation of the printer (printing apparatus) 1
including the transporting roller mechanism 19 will be described
with reference to FIGS. 1 and 2.
[0097] When the recording sheet P fed by the sheet-feed roller 22
reaches the upstream vicinity of the transporting roller mechanism
19, the motor 61 drives to introduce the recording sheet P between
the transporting roller 31 and the driven rollers 32. Then, the
rollers 31 and 32 transport the recording sheet P at a constant
speed to a position below the ejection head 51 located on the
downstream side.
[0098] Because the transporting roller 31 has the high-friction
layer 50, and because the driven rollers 32 are arranged at a
position where they come into contact with the high-friction layer
50, a force with which the transporting roller 31 and the driven
rollers 32 nip the recording sheet P increases. Thus, the
efficiency of transporting the recording sheet P further
increases.
[0099] When the printing start end of the recording sheet P reaches
a predetermined printing position immediately below the ejection
head 51, printing is started.
[0100] Thereafter, when the start end of the recording sheet P
reaches the sheet-discharging portion 4, i.e., the
sheet-discharging roller 41 and the sheet-discharge serrated roller
42, discharge of the recording sheet P nipped therebetween is
started.
[0101] Herein, the driving force of the motor 61 is transmitted to
the transporting roller 31 via the first driving gear 35 and is
then transmitted to the sheet-discharging roller 41 via the second
driving gear 36, rotating the sheet-discharging roller 41 while the
transporting roller 31 transports the recording sheet P. At this
time, because both the first driving gear 35 and the second driving
gear 36 are disposed on one end side of the transporting area CA of
the transporting roller 31, the torque acting on the transporting
roller 31 (roller body 16) does not act on the transporting area
CA. Therefore, slip does not occur at the seam 80 (intermediate
straight portion 86) in the transporting area CA. Accordingly, it
is possible to prevent an inconvenience, such as skewed
transportation of the recording sheet P, and to suppress
degradation in transportation precision and printing precision.
[0102] On the other hand, the driving force of the motor 61
transmitted to the transporting roller 31 via the first driving
gear 35 is transmitted to another device 38 via the third driving
gear 37. In this case, because the third driving gear 37 is
disposed on the other end side of the transporting roller 31
opposite the first driving gear 35 across the transporting area CA,
the transporting area CA is subject to the torque exerted by the
operation of the device 38. However, because the third driving gear
37 is connected to the device 38, which does not operate while the
transporting roller 31 transports the recording sheet P, the
recording sheet P is not transported during operation of the device
38. Thus, the transportation precision and the printing precision
are not degraded. In addition, in this embodiment, because the seam
80 of the transporting roller 31 in the transporting area CA is the
intermediate straight portion 86, and the seam 80 has a minimum
length, degradation in transportation precision and printing
precision due to the seam 80 can be further suppressed.
[0103] As has been described above, in this embodiment, because
both the first driving gear 35 and the second driving gear 36 are
disposed on one end side of the transporting area CA of the
transporting roller 31, degradation in transportation precision and
printing precision of the recording sheet P can be suppressed.
Furthermore, in this embodiment, because the seam 80 constitutes
the winding portion 85, formed by fitting the staggered portions
110, on one end side of the transporting roller 31 where the first
driving gear 35 and the second driving gear 36 are disposed, and
because the seam 80 has the crossing portions 85a, it is possible
to prevent slip in the central axis 16a direction from occurring at
the seam 80. Thus, deformation of the transporting roller 31
(roller body 16) can be suppressed, and degradation in
transportation precision of the transporting roller 31 due to
deformation can be suppressed.
[0104] Furthermore, in this embodiment, the third driving gear 37
provided on the other end side of the transporting roller 31 is
connected to the device 38, which does not operate while the
transporting roller 31 transports the recording sheet P. Thus, the
driving force of the motor 61 can be efficiently utilized without
causing degradation in transportation precision, which contributes
to reduction in size and cost of the apparatus. In addition, in
this embodiment, because the seam 80 has the crossing portions 85b
on the other end side of the transporting roller 31 where the third
driving gear 37 is disposed, it is possible to prevent slip in the
central axis 16a direction from occurring at the seam 80. Thus,
deformation of the transporting roller 31 (roller body 16) can be
suppressed, and degradation in transportation precision of the
transporting roller 31 due to deformation can be suppressed.
[0105] Although a preferred embodiment of the invention has been
described with reference to the attached drawings, the invention is
of course not limited to such an example. The shapes, combinations,
and the like of the components described above are merely examples,
and they may be variously modified on the basis of the design
requirement or the like, within a scope not departing from the gist
of the invention.
[0106] For example, in the above-described embodiment, the first
driving gear 35 and the second driving gear 36 are provided on one
end side of the transporting roller 31, and the third driving gear
37 is provided on the other end side of the transporting roller 31.
However, the configuration is not limited thereto but may be such
that only the first driving gear 35 and the second driving gear 36
are provided on one end side of the transporting roller 31.
[0107] Furthermore, the above-described embodiment shows an example
in which the rotational driving force transmitted via the second
driving gear 36 drives the sheet-discharging roller 41. However,
the configuration is not limited thereto but may be such that the
rotational driving force is transmitted to another processing unit
that performs printing-related processing. In this case, the other
processing unit may perform predetermined processing while the
recording sheet P is transported by the transporting roller 31 or
while the recording sheet P is not transported.
[0108] Furthermore, in the above-described embodiment, the winding
portions 85 of the seam 80 of the roller body 16 are formed of the
rectangular projections 61c and the rectangular recesses 61d.
However, other than this shape, for example, as shown in FIG. 9A,
the crossing portions 85a of the winding portions 85 may be
inclined with respect to the peripheral direction (the top-bottom
direction in FIG. 9A) so as to cross the axis parallel to the
central axis 16a at an angle .alpha.. This configuration enables
the ends of the projections 61c to easily fit to the corresponding
recesses 61d when the end surfaces are brought toward each other by
pressing the metal plate. Thus, the roller body 16 can be prevented
from being strained or twisted.
[0109] Furthermore, the winding portions 85 may have an alternating
arch shape (a sine wave shape), as shown in FIG. 9B, or a zigzag
shape formed of triangular projections 61c and recesses 61d, as
shown in FIG. 9C.
[0110] Furthermore, in the above-described embodiment, the second
driving gear 36 and the third driving gear 37 are engaged with the
engaging holes 71 and 72 provided in the roller body 16,
respectively, so that the second driving gear 36 and the third
driving gear 37 are mounted to the roller body 16 in a
non-rotatable manner. However, the configuration is not limited
thereto, and, for example, as shown in FIGS. 10A and 10B, an
engaging portion 73, which is a D-shaped cutout, may be formed at
an end of the roller body 16. The engaging portion 73 is formed at
the end of the cylindrical roller body 16 (transporting roller 31).
As shown in FIG. 10A, an opening 73a is formed by removing a
rectangular portion in plan view from the cylindrical roller body
16 so that the side surface at the end has a D shape, as shown in
FIG. 10B.
[0111] Therefore, by engaging a connecting part such as a gear (not
shown) with the D-shaped engaging portion 73, the connecting part
can be mounted to the roller body 16 in a non-freewheeling manner.
Furthermore, the engaging portion 73 has the slot-like opening 73a
communicating with the inner hole of the hollow pipe (roller body
16). Thus, the connecting part can also be mounted to a developing
roller 510 in a non-freewheeling manner using the opening 73a. More
specifically, a projection is formed on the connecting part, and
the projection is fitted to the opening 73a to prevent
freewheeling.
[0112] Furthermore, as shown in FIGS. 11A and 11B, it is also
possible to form an engaging portion 74 having a slot 74a and a
D-shaped cutout portion 74b at the end of the roller body 16. In
this engaging portion 74, the D-shaped cutout portion 74b is formed
at the outer end of the roller body 16, and the slot 74a is formed
on the inner side of the D-shaped cutout portion 74b. As shown in
FIG. 11A, the slot 74a is formed by cutting a portion of the roller
body 16 away in the peripheral direction, up to substantially half.
The D-shaped cutout portion 74b is located on the outer side of the
slot 74a and has an opening 74c extending in the direction
perpendicular to the slot 74a. The D-shaped cutout portion 74b has
a pair of bent pieces 74d and 74d on both sides of the opening 74c.
That is, as shown in FIG. 11B, by bending the bent pieces 74d and
74d toward the central axis of the roller body 16, the portions
corresponding to the bent pieces 74d and 74d are recessed from the
cylindrical outer peripheral surface of the roller body 16.
[0113] Therefore, by engaging a connecting part such as a gear (not
shown) with the slot 74a or the D-shaped cutout portion 74b, the
connecting part can be mounted to the roller body 16 (transporting
roller 31) in a non-freewheeling manner. Furthermore, in this
engaging portion 74, the connecting part can also be mounted to the
roller body 16 in a non-freewheeling manner using the opening 74c
formed between the bent pieces 74d. More specifically, a projection
is formed on the connecting part, and the projection is fitted to
the opening 74c to prevent freewheeling.
[0114] Furthermore, as shown in FIGS. 12A and 12B, it is also
possible to form an engaging portion 75 having a slot 75a and an
opening 75b at the end of the roller body 16. In this engaging
portion 75, the opening 75b is formed at the outer end of the
roller body 16, and the slot 75a is formed on the inner side of the
opening 75b. As shown in FIG. 12A, the slot 75a is formed by
cutting a portion of the roller body 16 away in the peripheral
direction, up to substantially half. As shown in FIG. 12B, the
opening 75b is located on the outer side of the slot 75a and is
formed by removing a rectangular portion in plan view from the
roller body 16 so that the side surface at the end has a D
shape.
[0115] Therefore, by engaging a connecting part such as a gear (not
shown) with the slot 75a or a D-shaped portion formed by the
opening 75b, the connecting part can be mounted to the roller body
16 in a non-freewheeling manner. Furthermore, also in this engaging
portion 75, similarly to the engaging portion 73 shown in FIGS. 10A
and 10B, the connecting part can be mounted to the roller body 16
in a non-freewheeling manner using the opening 75b.
[0116] The engaging hole 71 and the engaging portions 73, 74, and
75 can be provided by cutting the roller body 16 obtained by
pressing the above-described metal plate 60. For example, the
D-shaped engaging portion 73 shown in FIGS. 10A and 10B can be
formed by cutting the end to form the opening 73a.
[0117] However, performing additional machining on the roller body
16 means adding another machining step just for forming the
engaging portion and decreases the cost and time efficiencies.
Thus, it is preferable that unfolded engaging portions, which
constitute the engaging portion when being pressed, be formed in
the metal plate before the roller body 16 is pressed, and the
engaging portion be formed at the same time when the metal plate is
pressed into the roller body 16.
[0118] More specifically, when a large metal plate is pressed into
the long, narrow, rectangular plate-like metal plate 60, as shown
in FIG. 5, unfolded engaging portions in the shape of notches,
projections, holes, slots, or the like are formed. For example, as
shown in FIG. 13A, the through-holes 71a and 71a, which are
unfolded engaging portions 76a, are provided at predetermined
positions at an end of the metal plate 60. Then, by pressing the
metal plate 60, the through-holes 71a and 71a are made to face each
other, whereby the engaging hole 71 shown in FIGS. 6A and 6B can be
formed.
[0119] As shown in FIG. 13B, by forming unfolded engaging portions
76b by cutting the end of the metal plate 60 in a predetermined
shape, the engaging portion 74 shown in FIGS. 11A and 11B can be
formed by pressing the metal plate 60. That is, the engaging
portion 74 can be formed by forming a pair of notches (recesses)
74e and 74e and a pair of projections 74f and 74f, which are the
unfolded engaging portions 76b. In this example, however, because
the projections 74f and 74f need to be bent to the inside and
pressed into the bent pieces 74d after the metal plate 60 is
pressed, the cost and time efficiencies in the machining process
cannot be sufficiently improved.
[0120] As shown in FIG. 13C, by forming unfolded engaging portions
76c by cutting the end of the at the metal plate 60 in a
predetermined shape, the engaging portion 75 shown in FIGS. 12A and
12B can be formed by pressing the metal plate 60. That is, the
engaging portion 75 can be formed by forming a pair of notches
(recesses) 75c and 75c and a pair of projections 75d and 75d, which
are the unfolded engaging portions 76c. In this example, by bending
the projections 75d and 75d into an arch shape when the metal plate
60 is pressed, the opening 75b shown in FIG. 12B can be formed
between the projections 75d and 75d. Therefore, there is no need to
perform additional machining on the roller body 16 formed by
pressing, and the cost and time efficiencies in the machining
process can be sufficiently improved.
[0121] Furthermore, it is preferable that the ceramic particles
(for example, alumina particles) constituting the high-friction
layer 50 described in the above embodiment have a particle diameter
in the range of 15 .mu.m to 90 .mu.m, and that a weighted average
particle diameter (average particle diameter), i.e., the center
diameter, be adjusted to 45 .mu.m.
[0122] That is, as shown in FIG. 14, alumina particles (inorganic
particles) having an average particle diameter (center diameter)
larger than the distance d1 (30 .mu.m) at the outer peripheral
surface of the seam 80 are used. Furthermore, regarding the
particle diameter distribution (size range), it is preferable that
particles having an average particle diameter smaller than the
distance d1 at the outer peripheral surface of the seam 80 and
larger than the distance d2 (10 .mu.m) at the inner peripheral
surface be contained. Furthermore, it is preferable that the
minimum particle diameter of the particle diameter distribution be
larger than the minimum distance between the end surfaces 61a and
61b at the seam 80, i.e., the distance d2 at the inner peripheral
surface.
[0123] By forming the high-friction layer 50 in this manner, no
groove due to the gap between the end surfaces 61a and 61b of the
metal plate 60 is formed especially at the seam 80, and the gap
between the end surfaces 61a and 61b is filled mainly with the
alumina particles 95.
[0124] That is, because the alumina particles 95 having an average
particle diameter larger than the distance d1 at the outer
peripheral surface of the seam 80 are used, most of the alumina
particles 95 do not enter the seam 80 but are deposited on the
outer peripheral surface of the roller body 16 with a resin film
151 therebetween, as shown in FIG. 14. Therefore, even though the
seam 80 has the gap between the end surfaces 61a and 61b of the
metal plate 60, the groove due to the gap is not formed because the
alumina particles 95 cover the gap.
[0125] Furthermore, the alumina particles 95 having a particle
diameter distribution (size range) such that particles 95a smaller
than the distance d1 at the outer peripheral surface of the seam 80
and larger than the distance d2 (10 .mu.m) at the inner peripheral
surface side are contained are used. Thus, the particles 95a enter
the gap formed at the seam 80 and stay there, assuredly preventing
a groove due to the seam 80 from being formed.
[0126] Furthermore, even if a force acts on the roller body 16
(transporting roller 31) in the direction in which the gap is
narrowed when the roller body 16 is used, because the alumina
particles 95a in the gap resist this force, deformation of the
roller body 16 (transporting roller 31) can be suppressed.
Therefore, in the transporting roller mechanism 19 having the
transporting roller 15, uneven transportation due to deformation of
the transporting roller 15 is prevented.
[0127] Furthermore, the alumina particles 95 whose minimum particle
diameter in the particle diameter distribution is larger than the
minimum distance between the end surfaces 61a and 61b of the seam
80, i.e., the distance d2 at the inner peripheral surface, are
used. Thus, no alumina particles 95 enter the roller body 16
through the gap formed at the seam 80, when the high-friction layer
50 is formed by arranging the alumina particles 95 over the surface
of the roller body 16. This simplifies the subsequent processing
such as cleaning the inside of the roller body 16, increasing the
production efficiency.
[0128] Furthermore, as shown in FIG. 15A, openings 170 may be
provided in some portions of the seam 80 of the roller body 16
shown in the above-described embodiment.
[0129] As shown in FIG. 15B, the seam 80 formed in the roller body
16 has a groove-like structure in which the end surfaces 61a and
61b are in tight contact with each other at the inner periphery and
are separated at the outer periphery.
[0130] The seam 80 may also have a structure in which the end
surfaces 61a and 61b are not in contact with each other and are
separated with a small gap therebetween. Because the seam 80 is
formed over the overall length of the transporting roller 31, if
grease applied to the bearings is deposited on the surface of the
transporting roller 31, the grease flows along the seam 80 due to
capillarity. In particular, the smaller the seam 80 (the maximum
distance d1 between the end surfaces 61a and 61b) to increase the
strength of the transporting roller 31, the greater the
capillarity, making the grease easy to flow along the seam 80.
[0131] To counter this, as shown in FIG. 15C, the opening 170 is
provided at a portion of the seam 80 of the roller body 16. As
shown in FIG. 15C, the opening 170 is formed of notches 76 and 77
provided in the end surfaces 61a and 61b, respectively, that
constitute the seam 80. The maximum distance d2 between the notches
76 and 77 is set to, for example, about 1 mm or more when the end
surfaces 61a and 61b are in contact with each other, and the
notches 76 and 77 serve as the opening 170.
[0132] The opening 170 is provided in an area of the seam 80 formed
over the overall length of the transporting roller (roller body 16)
except for the areas having the high-friction layer 50 and the
areas supported by the bearings 26. That is, because the
high-friction layer 50 is formed at substantially the middle
portion of the transporting roller 31, and because the ends of the
transporting roller 31 are supported by the bearings, the
transporting roller 31 has at least two openings 170.
[0133] The openings 170 are provided to prevent the grease
(lubricant oil) applied to the bearings from flowing along the seam
80 (the gap between the end surfaces 61a and 61b) up to the
high-friction layer 50. That is, flow of the grease due to
capillarity is prevented by providing the openings 170 in some
portions of the seam 80. More specifically, by providing the
openings 170 in the seam 80, at positions between the area having
the high-friction layer 50 and the areas supported by the bearings
26, the grease is prevented from reaching the high-friction layer
50. Then, by adjusting the size of the openings 170 (the maximum
distance, d2, between the notches 76 and 77), flow of the grease
due to capillarity can be assuredly prevented.
[0134] It is not limited to the case where the notches 76 and 77
constituting the openings 170 are provided on the end surfaces 61a
and 61b forming the seam 80. That is, as shown in FIG. 15D, it is
possible that a notch 78 is provided only on one of the end
surfaces 61a and 61b (for example, the end surface 61a) forming the
seam 80, and the notch 78 and the end surface 61b constitute the
openings 170. Furthermore, the shape of the openings 170 is not
limited to rectangular, but may be circular, etc.
[0135] Furthermore, the seam 80 formed on the roller body 16 may
have a shape shown in FIG. 16. That is, in the seam 80, a first end
surface 174 and a second end surface 175 are in contact with each
other at the outer peripheral surface 16a of the roller body 16.
The gap between the first end surface 174 and the second end
surface 175 gradually increases from the radially outer side to the
inner side. Furthermore, the shape of the first end surface 174 and
second end surface 175 are the same over the overall length of the
roller body 16, except for the winding portions.
[0136] Furthermore, the first angle .alpha. formed between the
first end surface 174 and the outer peripheral surface 16a and the
second angle .beta. formed between the second end surface 175 and
the outer peripheral surface 16a are both smaller than
90.degree..
[0137] The first end surface 174 and the second end surface 175 of
the seam 80 are in contact with each other at the outer peripheral
surface 16a, and the smoothness of the outer peripheral surface 16a
increases at the seam 80. Accordingly, when the transporting roller
31 rotates, the outer peripheral surface of the transporting roller
31 can be stably in contact with the recording sheet P. Thus, the
recording sheet P can be precisely transported.
[0138] The shape of the seam 80 may be such that, as shown in FIG.
17, the first angle .alpha. formed between the first end surface
174 of the seam 80 and the outer peripheral surface 16a is smaller
than 90.degree., and the second angle .beta. formed between the
second end surface 175 and the outer peripheral surface 16a is
equal to or larger than 90.degree.. That is, the first end surface
174 and the second end surface 175 at the connecting portion 80 may
be inclined toward a predetermined direction in the peripheral
direction.
[0139] The seam 80 is formed by going through the following
process. First, the metal plate 60 is formed by punching in
progressive pressing. Then, end-surface adjustment treatment is
performed on the first end surface 174 and the second end surface
175 of the metal plate 60 to adjust the inclinations of the first
end surface 174 and second end surface 175 with respect to the
outer peripheral surface 16a.
[0140] As shown in FIG. 18, the inclinations of the first end
surface 174 and second end surface 175 with respect to the outer
peripheral surface 16a are adjusted by pressing. By this
adjustment, both the first angle .alpha. formed between the first
end surface 174 and the outer peripheral surface 16a and the second
angle .beta. formed between the second end surface 175 and the
outer peripheral surface 16a become smaller than 90.degree..
[0141] Therefore, when the metal plate 60 is bent into a
cylindrical roller body 16, the first end surface 174 and the
second end surface 175 are in contact with each other at least at
the outer peripheral surface 16a.
[0142] Because the roller body 16 (transporting roller 31) is
formed of the metal plate 60 having a residual curl from a steel
plate coil, it is preferable that the inner peripheral surface of
the coil constitute the inner peripheral surface of the roller body
16.
[0143] That is, the metal plate 60 has a residual curl from the
steel plate coil such that the inner peripheral surface of the
steel plate coil is concave. That is, the metal plate 60 being
formed into the roller body 16 has a residual curl such that it is
curved toward the inner peripheral surface of the roller body
16.
[0144] Thus, the residual curl does not act, at least, in the
direction in which the seam 80 of the roller body 16 opens.
Therefore, compared to the case where the metal plate 60 has a
residual curl such that it is curved toward the outer peripheral
surface of the roller body 16, the seam 80 of the roller body 16 is
less likely to open. Thus, even when a stress acts in the direction
in which the seam 80 of the roller body 16 opens, the seam 80 can
be prevented from being opened. Thus, the transporting roller 31
having high transportation precision can be obtained.
[0145] Furthermore, the peripheral direction (bending direction) of
the roller body 16 and the winding direction (the rolling direction
of the metal plate 60) of the steel plate coil are the same. Thus,
the bending direction of the metal plate 60 constituting the roller
body 16 and the direction of the curve of the residual curl can be
matched. This allows the residual curl of the metal plate 60
constituting the roller body 16 to act in the direction in which
the seam 80 of the roller body 16 is closed. Therefore, the seam 80
of the roller body 16 is more effectively prevented from being
opened.
[0146] Furthermore, it is preferable that shear drop, burrs, and
the like, formed on the cutting surfaces of the metal plate 60 be
located at the inner periphery of the roller body 16 in the
punching process of the roller body 16.
[0147] That is, the roller body 16 (transporting roller 31) is
formed of the metal plate 60 that is formed by punching, as shown
in, for example, FIGS. 19A and 19B. The metal plate 60, serving as
the base material of the roller body 16, is bent into a cylindrical
shape such that a top surface C2 facing a male mold 131, shown in
FIG. 19A, constitutes the outer peripheral surface. Thus, the seam
80 where the end surfaces 61a and 61b are in contact with each
other is formed.
[0148] Thus, even when shear drops sd, sear planes sp, fracture
surfaces bs, and burrs (not shown) are formed in the punched metal
plate 60 in the punching process, as shown in FIG. 19B, it is
preferable that the top surface C2, where the relatively smooth
shear drops sd are formed, be located at the outer periphery of the
roller body 16. In other words, it is preferable that a bottom
surface C1 of the metal plate 60 that is continuous with the burrs
and the fracture surfaces bs be located at the inner periphery of
the roller body 16.
[0149] Thus, the seam 80 can be prevented from being opened due to
the irregularity caused by the burrs and the fracture surfaces bs,
when the end surfaces 61a and 61b of the metal plate 60 are brought
into contact with each other to form the roller body 16 having the
seam 80.
[0150] Therefore, the precision of the seam 80 of the roller body
16 can be increased to provide the transporting roller 15 having
high transportation precision. Furthermore, because the burrs are
located on the inner peripheral surface of the roller body 16, the
burrs are prevented from protruding from the outer peripheral
surface of the roller body 16. Thus, a burr removing process can be
eliminated, and the production efficiency can be improved.
[0151] Furthermore, in addition to the configurations of the
unfolded engaging portions shown in FIGS. 13A to 13C, the
configurations in which the unfolded engaging portions are formed
not at both ends of the metal plate 60 but in the vicinity of the
center line in the widthwise direction (bending direction), as
shown in FIG. 20A to 20C, are possible. That is, as shown in FIG.
20A, by forming an unfolded engaging portion 76d formed of a long,
narrow, rectangular notch at the end, the engaging portion 73 shown
in FIG. 10 can be formed. Furthermore, by forming an unfolded
engaging portion 76e formed of a T-shaped notch shown in FIG. 20B,
the engaging portion 74 shown in FIG. 11 can be formed.
Furthermore, by forming an unfolded engaging portion 76f formed of
a substantially T-shaped notch shown in FIG. 20C, the engaging
portion 75 shown in FIG. 12 can be formed.
[0152] Thus, by forming the unfolded engaging portions 76d to 76f
in the vicinity of the center line in the bending direction, the
engaging portions 73 to 75 formed of the unfolded engaging portions
76d to 76f can be more precisely formed.
[0153] Although the seam 80 of the transporting roller 31 (roller
body 16) according to this embodiment extends parallel to the
central axis of the roller body 16 formed of a cylindrical hollow
pipe, the invention is not limited to such a configuration. For
example, the seam formed between the ends of the metal plate 60,
serving as the base material, may overlie a straight line on the
outer peripheral surface of the cylindrical pipe (roller body),
parallel to the central axis of the cylindrical pipe, not over a
line segment, but only at one or a plurality of points.
[0154] More specifically, as shown in FIG. 21A, a seam 81 may
extend over the outer peripheral surface of the roller body 16 in
the peripheral direction, from one end to the other end of the
roller body 16, not parallel but at an angle to the central axis
16a of the roller body 16. In order to form such a seam 81, not the
above-described long, narrow rectangular metal plate 60, but a
metal plate 60a in the shape of a long, narrow parallelogram, as
shown in FIG. 21B, is used as the metal plate serving as the base
material, and the metal plate is pressed such that a straight line
16b is the central axis. Thus, the roller body 16 having the seam
81 at an angle to the central axis 16a, as shown in FIG. 21A, is
obtained.
[0155] In the roller body 16 shown in FIG. 21A, the seam 81 extends
from one end to the other end of the roller body 16 while making
less than one turn around the circumference. This simplifies
pressing of the metal plate 60a. However, as shown in FIG. 21C, a
seam 82 may extend from one end to the other end of the roller body
16 while making one or more turns, i.e., spirally, around the
circumference. In such a case, the angle .theta. in the long narrow
parallelogram metal plate 60a shown in FIG. 21B, serving as the
base material, is further reduced.
[0156] By forming the seam that does not overlie the straight line
parallel to the central axis of the cylindrical pipe (roller body
16) over a line segment, but only at one or a plurality of points,
the transportation speed of the transporting roller 31 having the
roller body 16 is constant when it transports the recording sheet P
in cooperation with the driven roller, that is, when it feeds the
recording sheet P. Accordingly, uneven transportation is more
assuredly prevented.
[0157] That is, as shown in FIG. 22, the transporting roller 31 is
in contact with the recording sheet P during sheet feeding at,
basically, the straight line L on the outer peripheral surface,
i.e., the straight line parallel to the central axis 16a.
Therefore, as has been described above, when the seam 80 of the
transporting roller 31 (roller body 16) is parallel to the central
axis 16a of the roller body 16, the entirety of the seam 80 of the
transporting roller 31 is temporarily (momentarily) in contact with
the recording sheet P. If there is a groove due to the seam 80, the
groove temporarily comes into contact with the recording sheet P at
once, in other words, the overall width of the recording sheet P
temporarily comes into contact with the groove due to the seam 80,
though the transporting roller 31 according to this embodiment does
not suffer such a problem because it has no groove due to the seam
80. As a result, because the groove is recessed from the outer
peripheral surface of the transporting roller 31 and has a lower
contact resistance to the recording sheet P, the transportation
speed temporarily decreases. Thus, uneven transportation
occurs.
[0158] However, by forming the seam as shown in FIGS. 21A and 21C,
even if a groove due to the seam is formed, the groove comes into
contact with the recording sheet P during sheet feeding only at one
or more points at a time. Therefore, compared to a case where the
other surface (line) of the transporting roller 31 comes into
contact with the recording sheet P, the contact resistance hardly
changes. Thus, the transportation speed becomes constant, and
uneven transportation is prevented.
[0159] Furthermore, as shown in FIG. 23A, other than the example
described above, the seam of the transporting roller (roller body
16) formed of a cylindrical hollow pipe may have rectangular
wave-like winding portions 85 formed of straight portions 85a
parallel to the central axis of the roller body 16 and straight
portions 85b that are perpendicular thereto. Even if grooves due to
the seam are formed in the seam having the winding portions 85,
because the grooves do not come into contact with recording sheet P
at once over the overall width of the recording sheet P during
sheet feeding, the transportation speed is substantially constant,
and uneven transportation is prevented.
[0160] Furthermore, the winding portions 85 may be formed over the
overall length of the roller body 16, as shown in FIG. 23B, or may
be formed selectively at both ends of the roller body 16 except for
the middle portion thereof, as shown in FIG. 23C. When the winding
portions 85 are formed only at both ends, as shown in FIG. 23C, the
intermediate straight portion 86 parallel to the central axis of
the roller body 16 extends between the winding portions 85.
Although not shown, the intermediate straight portion 86 between
the winding portions 85 may extend at an angle to the central axis
16a, as shown in FIG. 21A.
[0161] Furthermore, when the winding portions 85 are formed only at
both ends with the intermediate straight portion 86 therebetween,
it is preferable that the high-friction layer 50 be formed on the
middle portion straight portion 86.
[0162] If the winding portions 85 are formed at the seam, or if the
winding portions 85 are formed by fitting projections and recesses,
it is difficult to fit these winding portions 85 (fitting portions)
together in accordance with the design and bring the tips of the
projections into contact with the corresponding recesses without
leaving a gap therebetween. Thus, if the winding portions 85 are
formed over the overall length of the roller body 16, the roller
body 16 tends to be strained or twisted. To counter this, by making
the winding portions 85 only at both ends, as shown in FIG. 23C,
the roller body 16 can be prevented from being strained or twisted.
Furthermore, by making the intermediate straight portion 86, not
the winding portions 85, serve as the middle portion corresponding
to the high-friction layer 50, which directly comes into contact
with the recording sheet P, it is possible to assuredly prevent the
area which directly comes into contact with the recording sheet P
from being strained or twisted.
[0163] Furthermore, when the winding portions 85 are formed over
the overall length of the roller body 16, as shown in FIG. 23B, a
seam 87 including the winding portions 85 may be formed of a
plurality of crossing portions 87a consisting of straight portions
85b; first straight portions 87b connecting the ends of the
crossing portions 87a on one side; and second straight portions 87c
connecting the ends of the crossing portions 87a on the other side,
as shown in FIG. 24A. Herein, the first straight portions 87b and
the second straight portions 87c are formed substantially parallel
to the central axis of the roller body 16, and the crossing
portions 87a are formed perpendicular to the first straight
portions 87b and the second straight portions 87c, that is,
perpendicular to the central axis of the roller body 16.
Furthermore, the second straight portions 87c are shorter than the
first straight portions 87b.
[0164] When the seam 87 having such a configuration is formed, it
is preferable that the distance d3 between the opposed ends at the
second straight portions 87c be larger than the distance d4 between
the opposed ends at the first straight portions 87b. Note that the
distance d3 and the distance d4 between the ends are the distances
between the ends of the gaps formed on the outer peripheral surface
of the roller body 16.
[0165] This configuration increases the shape and size accuracy of
the roller body 16 in the shape of a cylindrical hollow pipe, and
thus, uneven transportation due to deformation or the like of the
roller body 16 can be prevented. That is, in the metal plate
serving as the base material of the roller body 16, one end
constituting the second straight portion 87c is a protruding piece
87d whose outline is defined by the adjacent crossing portions 87a
and 87a and the second straight portion 87c that connects the ends
of the crossing portions 87a and 87a. Therefore, when the metal
plate is pressed and the protruding piece 87d is brought toward the
opposing end, the tip of the protruding piece 87d is not
sufficiently bent in a cylindrical shape and is higher than the
opposing end by the dimension t1, as shown by a two-dot chain line
in FIG. 24B, forming a stepped portion at the second straight
portion 87c. Due to the stepped portion, the roller body 16 tends
to be deformed, making it difficult to achieve high shape and size
accuracy.
[0166] By making the distance d3 between the ends at the second
straight portion 87c larger than the distance d4 between the ends
at the first straight portion 87b, which is longer than the second
straight portion 87c, the dimension t2, by which the tip of the
protruding piece 87d is higher than the opposing end, becomes
smaller than the dimension t1, as shown by a solid line in FIG.
24B. Thus, the stepped portion is prevented from being formed at
the second straight portion 87c.
[0167] Although FIG. 24B shows the dimension t2 in a larger scale
for clarity's sake, the dimension t2 is almost zero in actuality,
and there is substantially no stepped portion. That is, by
preventing the formation of the stepped portion at the second
straight portion 87c, deformation or the like of the roller body 16
due to the stepped portion is suppressed. Thus, the shape and size
accuracy can be increased.
[0168] Furthermore, when the winding portions 85 are formed only at
both ends of the roller body 16, as shown in FIG. 23C, it is
preferable that the distance d5 between the opposed ends at the
crossing portions 87a (straight portions 85b) of the winding
portions 85 be smaller than the distance d6 between the opposed
ends at the intermediate straight portion 86, as shown in FIG.
25.
[0169] In this configuration, the distance d5 is relatively small,
and the gap between the ends at the crossing portions 87a is very
narrow. Thus, when the metal plate serving as the base material of
the roller body 16 is pressed, the opposed ends constituting the
crossing portions 87a prevents the slip from occurring between one
end and the other end in the lengthwise direction (axial
direction). Therefore, the roller body 16 (transporting roller 15)
is less likely to be strained or twisted, and uneven transportation
due to strain or twisting is prevented.
[0170] When the winding portions 85 are formed at only both ends of
the roller body 16, as shown in FIG. 23C, the distance d7 between
the opposed ends at the second straight portion 87c constituting
the protruding piece 87d of the winding portions 85 may be smaller
than the distance d6 between the opposed ends at the intermediate
straight portion 86, as shown in FIG. 25, or may be larger than the
distance d6.
[0171] By making the distance d7 smaller than the distance d6, the
gap between the opposed ends can be more easily made constant over
the overall length of the seam, and the shape and size accuracy of
the roller body 16 is further increased. That is, because the
length of the intermediate straight portion 86 is larger than the
length of the second straight portion 87c at the winding portions
85, the ends at the intermediate straight portion 86 can be more
precisely brought toward each other than the ends at the second
straight portion 87c. Thus, even if the distance between the ends
at the intermediate straight portion 86, where the precision of the
gap between the ends is relatively high, is increased to increase
the gap compared to the distance between the ends at the second
straight portion 87c, the gap can be made sufficiently constant.
Accordingly, uneven transportation due to strain or twisting of the
roller body 16 can be prevented.
[0172] On the other hand, if the distance d7 is larger than the
distance d6, as shown in FIG. 24B, the dimension t2, by which the
tip of the protruding piece 87d is higher than the opposing end,
decreases. Thus, the stepped portion is prevented from being formed
at the second straight portion 87c. Because the formation of the
stepped portion at the second straight portion 87c can be
prevented, deformation of the roller body 16 due to the stepped
portion can be suppressed. Thus, the shape and size accuracy can be
increased and uneven transportation is prevented.
[0173] Furthermore, in the above-described embodiment, the
transporting roller of the invention is applied to the transporting
roller 31 of the transporting roller mechanism 19. However,
transporting roller of the invention may be applied to the
sheet-discharging roller 41, the sheet-discharge serrated roller
42, or the driven rollers 32 (roller 32a) of the transporting
roller mechanism 19.
* * * * *