The present invention relates to a roller that transports a medium such as a paper sheet.
As this type of printing apparatus, there is known an ink jet printer that performs printing on a medium such as a paper sheet by ejecting liquid such as ink onto the medium that is being transported by transport rollers. As an example of this type of printer, there is provided a printer having spurs that nip and transport a medium subjected to printing (see, for example, JP-A-2006-347119). The spur of JP-A-2006-347119 is formed of a circular metal sheet (wheel) that has a plurality of tooth tips, and a molded member (holder) that is molded integrally with the metal sheet and supports the metal sheet in a rotatable manner. Two spurs are provided so as to be adjacent to each other in a width direction of the medium that intersects a transport direction of the medium. The spurs as described above transport the medium in such a manner that the tooth tips of the metal sheets are brought into contact with the medium. With this operation, the contact area between the medium and the spurs is reduced, thereby suppressing transfer of ink from the medium.
In the spur of JP-A-2006-347119, the metal sheet (wheel) is formed by press working, and hence the metal sheet is formed by cutting off tie-bar portions that couple a base material and the metal sheet to each other. Therefore, tie-bar cut portions (cut portions) are formed on the outer periphery of the metal sheet in addition to the tooth tips. The shape of the tie-bar cut portion is different from the shape of the tooth tip and is formed on a radially inner side of the metal sheet with respect to the tooth tip. Therefore, when the number of teeth of the metal sheet increases, an imaginary circle formed by connecting the tooth tips of the metal sheet into a circle differs from a perfect circle because the tooth cannot be formed at a portion where the tie-bar cut portion is formed. When the spurs are viewed in an axial direction (width direction of the medium) orthogonal to the side surfaces of the metal sheets thereof, if the tie-bar cut portions of the metal sheets adjacent to each other in the axial direction overlap each other or are distributed unevenly in a circumferential direction of the spurs, the shapes of the spurs differ from a perfect circle. As a result, the transport accuracy of the medium to be transported by the spurs may be decreased.
This problem may arise not only in the spurs described in JP-A-2006-347119 but also in rollers that transport a medium by metal sheets (wheels) having tie-bar cut portions.
An advantage of some aspects of the invention is that a printing apparatus including a roller capable of suppressing a decrease in the transport accuracy of a medium is provided.
Some aspects of the invention and operations and advantages thereof are described below.
A transport roller for a printing apparatus according to an aspect of the invention transports a medium. The transport roller includes a shaft that extends in a direction intersecting a transport direction of the medium, and a wheel group in which a plurality of toothed wheels arrayed in the direction in which the shaft extends are held by holders. The toothed wheel includes non-formation portions having no teeth. The non-formation portions of the plurality of toothed wheels of the wheel group are arranged with an interval therebetween in a circumferential direction of the toothed wheels. The non-formation portions are cut portions that are formed when the toothed wheel is cut off from a base. The teeth other than the teeth adjacent to the cut portions are arranged away from each other at regular intervals in a circumferential direction of the wheel group.
A transport roller for a printing apparatus according to an aspect of the invention transports a medium. The transport roller includes a shaft that extends in a direction intersecting a transport direction of the medium, and a wheel group in which a plurality of toothed wheels arrayed in the direction in which the shaft extends are held by holders. The toothed wheel includes non-formation portions having no teeth, each of the non-formation portions protruding radially outwardly from a root of teeth of the toothed wheel. The non-formation portions of the plurality of toothed wheels of the wheel group are arranged with an interval therebetween in a circumferential direction of the toothed wheels.
A transport roller for a printing apparatus according to an aspect of the invention transports a medium. The transport roller includes a shaft that extends in a direction intersecting a transport direction of the medium, and a wheel group in which a plurality of toothed wheels arrayed in the direction in which the shaft extends are held by holders, each of the plurality of toothed wheels being stacked alternately with each of the holders so that two adjacent toothed wheels are connected by one of the holders therebetween. The toothed wheel includes non-formation portions having no teeth. The non-formation portions of the plurality of toothed wheels of the wheel group are arranged with an interval therebetween in a circumferential direction of the toothed wheels.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
A printing apparatus according to a first embodiment of the invention is described below with reference to the drawings. The printing apparatus of this embodiment is an ink jet printer that forms characters and images on a paper sheet that is an example of a medium by ejecting ink that is an example of liquid onto the paper sheet.
As illustrated in
In the following description, the direction in which the paper sheet P is transported is defined as a “transport direction Y”, and a direction of a vertical component is defined as a “vertical direction Z”. The transport direction Y is a direction intersecting (preferably orthogonal to) the width direction X, and the vertical direction Z is a direction intersecting (preferably orthogonal to) the width direction X and the transport direction Y. In the width direction X, a leftward direction (in the direction of the front side of the drawing sheet) as viewed from an upstream side in the transport direction Y is defined as a “+X direction”, and a rightward direction (in the direction of the back side of the drawing sheet) as viewed from the upstream side in the transport direction Y is defined as a “−X direction”.
The printing section 12 is a so-called line head including liquid ejecting heads capable of simultaneously ejecting ink in the width direction X. The printing section 12 performs printing by ejecting ink toward the paper sheet P that is transported by the transport apparatus 20 so as to face the printing section 12.
The transport apparatus 20 includes a sheet feeding section 30 that transports the paper sheet P to the printing section 12, the sheet discharging section 40 that transports the paper sheet P subjected to printing by the printing section 12 to the outside of the casing 11, and a branching section 50 that switches back the paper sheet P subjected to printing on one side by the printing section 12 to transport the paper sheet P to the printing section 12 again at the time of duplex printing of the paper sheet P.
The sheet feeding section 30 includes a first sheet feeding portion 30A, a second sheet feeding portion 30B, and a third sheet feeding portion 30C that constitute, in the transport path 21, three sheet feeding paths along which the paper sheet P is transported to the printing section 12, and a support transport portion 30D that transports the paper sheet P transported from each of the sheet feeding portions 30A to 30C toward a downstream side in the transport direction Y while supporting the paper sheet P. The three sheet feeding paths constituted by the first sheet feeding portion 30A, the second sheet feeding portion 30B, and the third sheet feeding portion 30C join each other on an upstream side in the transport direction Y with respect to the support transport portion 30D.
The first sheet feeding portion 30A transports the paper sheet P along a first sheet feeding path 21a of the transport path 21 (sheet feeding path) that connects the printing section 12 to a paper sheet cassette 11a provided at the lower end of the casing 11. The first sheet feeding portion 30A is provided with a pickup roller 31, a separation roller pair 32, and a first sheet feeding roller pair 33 in this order from the upstream side to the downstream side in the transport direction Y along the first sheet feeding path 21a. The paper sheets P which are located uppermost of the paper sheets P stacked on the paper sheet cassette 11a are sent out by the pickup roller 31 and separated one by one by the separation roller pair 32. Then, one paper sheet P separated by the separation roller pair 32 is transported to the printing section 12 by the first sheet feeding roller pair 33.
The second sheet feeding portion 30B transports the paper sheet P along a second sheet feeding path 21b of the transport path 21 (sheet feeding path) that connects the printing section 12 to an insertion portion 11c to be exposed by opening a cover 11b provided on one side surface of the casing 11. The paper sheet P inserted from the insertion portion 11c is transported to the printing section 12 while being nipped by a second sheet feeding roller pair 34.
The third sheet feeding portion 30C transports the paper sheet P subjected to printing by the printing section 12 to the printing section 12 (support transport portion 30D) again along a third sheet feeding path 21c of the transport path 21 (sheet feeding path) that is provided so as to pass around the printing section 12. The third sheet feeding path 21c is provided with at least one transport roller pair (two transport roller pairs 35 in this embodiment), and a third sheet feeding roller pair 36. The third sheet feeding roller pair 36 is provided on a downstream side of the third sheet feeding path 21c with respect to the two transport roller pairs 35. A plurality of transport driven rollers 37 are provided on an upstream side of the third sheet feeding path 21c with respect to the third sheet feeding roller pair 36. The paper sheet P subjected to printing by the printing section 12 is transported while being guided along the third sheet feeding path 21c by the transport driven rollers 37 and nipped by the two transport roller pairs 35. The paper sheet P transported by the transport roller pairs 35 is transported while being guided by the transport driven rollers 37 which are provided on the downstream side of the third sheet feeding path 21c with respect to the transport roller pairs 35, and is then transported to the printing section 12 again while being nipped by the third sheet feeding roller pair 36.
The support transport portion 30D is provided in the transport path 21 (sheet feeding path) so as to face the printing section 12 in the vertical direction. The support transport portion 30D transports the paper sheet P by causing a transport belt 38 facing the printing section 12 to circulate while supporting, by electrostatic attraction, the paper sheet P on a belt surface that is the outer peripheral surface of the transport belt 38. Specifically, the transport belt 38 is an endless belt looped around two rollers that are a driving roller 39A to be rotated through driving of a driving source, and a driven roller 39B to be rotated along with the circulation of the transport belt 38. The transport belt 38 circulates along with the rotation of the driving roller 39A and is charged with static electricity by a charging roller (not shown) that is brought into contact with the belt surface while the transport belt 38 is circulating. With the static electricity generated as a result of charging the transport belt 38, the transport belt 38 attracts the paper sheet P on the flat belt surface which is formed between the driving roller 39A and the driven roller 39B and transports the attracted paper sheet P toward the downstream side in the transport direction Y while causing the paper sheet P to face the printing section 12.
The sheet discharging section 40 transports the paper sheet P along a sheet discharging path 21d of the transport path 21 that connects the printing section 12 to a discharging port 11d through which the paper sheet P subjected to printing is discharged. The paper sheet P discharged from the discharging port lid is mounted on a mounting table lie provided in the casing 11. The sheet discharging section 40 includes at least one sheet discharging roller pair (five sheet discharging roller pairs 41 in this embodiment). The sheet discharging roller pair 41 transports the paper sheet P along the sheet discharging path 21d while nipping the paper sheet P. Further, one or a plurality of driven rollers 42 are provided between the sheet discharging roller pairs 41 adjacent to each other in the sheet discharging path 21d.
The branching section 50 transports the paper sheet P along a branching path 21e that branches from an upstream portion of the sheet discharging path 21d in the transport path 21 and then transports the paper sheet P toward the printing section 12 again along the branching path 21e. The branching section 50 includes a branching mechanism 51 that is provided on a downstream side in the transport direction Y with respect to the printing section 12 and is configured such that the paper sheet P transported to the sheet discharging path 21d can be guided to the branching path 21e and the paper sheet P transported to the branching path 21e can be guided to the third sheet feeding path 21c. The branching mechanism 51 is constituted by, for example, a flap. On a downstream side of the branching path 21e with respect to the branching mechanism 51, there are provided a branching transport roller pair 52 that transports the paper sheet P along the branching path 21e and is rotatable in forward/reverse directions, and a plurality of driven transport rollers 53 that guide the paper sheet P transported to the branching path 21e.
At the time of duplex printing, the paper sheet P subjected to printing on one side by the printing section 12 is guided to the branching path 21e by the branching mechanism 51 and is transported along the branching path 21e by driving the branching transport roller pair 52 to rotate in the forward direction. Then, the paper sheet P transported along the branching path 21e is transported in reverse along the branching path 21e by driving the branching transport roller pair 52 to rotate in the reverse direction, and the paper sheet P is guided to the third sheet feeding path 21c by the branching mechanism 51. That is, the branching transport roller pair 52 switches back the paper sheet P in the branching path 21e. Then, the paper sheet P guided to the third sheet feeding path 21c is transported along the third sheet feeding path 21c, and hence the positioning of the paper sheet P in the vertical direction Z is reversed. Accordingly, the paper sheet P is transported to the printing section 12 so that the surface of the paper sheet P which has not been subjected to printing faces the printing section 12.
Further, the transport apparatus 20 includes a correction roller pair 60 as an example of registration rollers that are provided between the support transport portion 30D and the joining position of the sheet feeding portions 30A to 30C in the transport path 21 and that correct skew feed of the paper sheet P. In a state in which the rotation of the correction roller pair 60 is stopped, the leading edge of the paper sheet P transported along each of the sheet feeding portions 30A to 30C abuts the correction roller pair 60, thereby correcting the skew feed of the paper sheet P. Then, the correction roller pair 60 is driven to transport the paper sheet P, the skew feed of which has been corrected, onto the support transport portion 30D.
The correction roller pair 60 includes a correction driving roller 70 as an example of the roller, and a correction driven roller 80 that is rotated in accordance with the rotation of the correction driving roller 70.
The correction driving roller 70 and the correction driven roller 80 are juxtaposed in the vertical direction Z. The correction driving roller 70 is rotatable through driving of a driving source such as an electric motor and is arranged at a position opposite the printing section 12 with respect to the transport path 21, that is, arranged below the printing section 12. The correction driven roller 80 is arranged at a position on the printing section 12 side with respect to the transport path 21, that is, above the correction driving roller 70. Further, a cleaning section 90 capable of cleaning the correction driving roller 70 is provided in the casing 11. The cleaning section 90 is arranged so as to be adjacent to a lower side of the correction driving roller 70.
As illustrated in
The correction driven roller 80 includes a driven shaft 81 that extends in the width direction X, and a plurality of driven rollers 82 (ten driven rollers 82 in this embodiment) that are fixed to the driven shaft 81. The driven rollers 82 are arranged at positions where the driven rollers 82 face the toothed rollers 72 in the vertical direction Z and are supported so as to be rotatable relative to the driven shaft 81. The driven rollers 82 are provided so that the peripheral surfaces thereof become uniformly circular peripheral surfaces with no irregularities and are configured to be brought into surface contact with the transported paper sheet P (see
As illustrated in
Further, torsion springs 96 are provided to the arm portions 92 located at both ends of the support plate 93 in the width direction X. The torsion springs 96 urge the tip ends of the arm portions 92 toward the correction driving roller 70. That is, the cleaning members 91 provided at the tip ends of the arm portions 92 are urged toward the toothed rollers 72. Thus, the cleaning members 91 are held in contact with the lower ends of the toothed rollers 72 of the correction driving roller 70. Each cleaning member 91 is formed of a material (foam) that is excellent in flexibility and water retention property, such as a foamed plastic, thereby being capable of wiping out ink adhering to the toothed rollers 72.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
That is, the hole 74a extends through the boss 74b. A plurality of recesses 74c (three recesses 74c in this embodiment) that are recessed from the outer peripheral surface of the boss 74b toward a radially inner side of the holder 74 are formed in the boss 74b.
In the six holders 74 other than the holder 74 located at the end of the +AX side (see
The inner diameter of the depression 74d is equal to the outer diameter of the boss 74b of the holder 74 adjacent in the axial direction AX. On the inner peripheral surface of the depression 74d, a plurality of engagement protrusions 74e (three engagement protrusions 74e in this embodiment) protrude radially inward in conformity with the recesses 74c of the holder 74 adjacent in the axial direction AX. In each of the six holders 74 other than the holder 74 located at the end of the +AX side (see
As illustrated in
The holder 74 having the wheel 73 mounted thereon is assembled onto the holder 74 adjacent in the axial direction AX. Specifically, the boss 74b of the holder 74 on the +AX side of
The toothed roller 72 thus constructed such that the wheels 73 and the holders 74 are stacked in the axial direction AX transports the paper sheet P in such a manner that the tip ends of the teeth 73a provided on the peripheral surface of the toothed roller 72 are brought into contact with the paper sheet P. That is, the teeth 73a of the toothed roller 72 function as projections configured to be brought into point contact with the paper sheet P. In other words, the wheel 73 includes projections configured to be brought into point contact with the paper sheet P.
As illustrated in
As understood from
As illustrated in
In this case, the plurality of tie-bar cut portions 73b are provided so as to satisfy relationships that the first distance is equal to or larger than the third distance and the second distance is smaller than the third distance.
The first distance and the second distance are described supplementarily.
That is, the first distance refers to a result of investigation that is conducted over the entire circumference of an imaginary circle connecting the vertices of the teeth 73a of the wheels 73 regarding a state in which a plurality of tie-bar cut portions 73b of the toothed roller 72 are present within a range of a predetermined arc on the imaginary circle. Specifically, when predetermined arcs are sequentially arranged clockwise around the imaginary circle (0° to 30°, 30° to 60°, . . . 330° to 360°), the first distance is a cumulative distance of the predetermined arcs in the state in which a plurality of tie-bar cut portions 73b are located within the range of the arc. If a plurality of tie-bar cut portions 73b are located within the range of all the arranged arcs, the first distance equals the total circumferential distance of the imaginary circle.
Details of the “predetermined arc” are exemplified.
As a precondition, it is assumed that six wheels 73 each having four tie-bar cut portions 73b with a phase difference of 90° (
By employing the above-mentioned predetermined arc (arc having a central angle of 30°), a plurality of tie-bar cut portions are arranged within the range of all or most of the predetermined arcs (arcs each having a central angle of) 30° sequentially arranged along the circumference of the imaginary circle when the tie-bar cut portions 73b are arranged at regular intervals as illustrated in
The second distance refers to a result of investigation that is conducted over the entire circumference of an imaginary circle connecting the vertices of the teeth 73a of the wheels 73 regarding a state in which a plurality of tie-bar cut portions 73b of the toothed roller 72 are not present within a range of a predetermined arc on the imaginary circle. Specifically, when predetermined arcs are sequentially arranged clockwise around the imaginary circle (0° to 30°, 30° to 60°, . . . 330° to 360°), the second distance is a cumulative distance of the predetermined arcs in the state in which a plurality of tie-bar cut portions 73b are not located within the range of the arc. Also in this case, an arc having a central angle of 30° is used as the predetermined arc. For example, when the predetermined arcs are sequentially arranged around the imaginary circle of
In the toothed roller 72 of this embodiment, the tie-bar cut portions 73b are provided at regular intervals in the circumferential direction when the toothed roller 72 is viewed in the axial direction AX. Specifically, in this embodiment, the first distance equals the total circumferential distance of the wheel 73, the second distance equals “0”, and the third distance equals a quarter of the total circumferential distance of the wheel 73. In order to satisfy those relationships, a shift amount Tc)(° of the tie-bar cut portions 73b of the wheels 73 adjacent to each other in the axial direction AX equals a value obtained by dividing 360° by a value obtained by multiplying the number of wheels 73 and the number of tie-bar cut portions 73b together. In this embodiment, the number of wheels 73 is six and the number of tie-bar cut portions 73b of the wheel 73 is four, and hence the shift amount Tc is 360°/(6×4)=15°. The shift amount Tc of the tie-bar cut portions 73b of the wheels 73 adjacent to each other in the axial direction AX according to this embodiment is defined by a minimum angle between the tie-bar cut portion 73b of a wheel 73 and the tie-bar cut portion 73b of another wheel 73 adjacent to the wheel 73 of interest in the axial direction AX.
The value of the tooth pitch Pt of the wheel 73 is adjusted (set) so as to achieve an arrangement state in which the plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed roller 72 are not distributed unevenly and all the teeth 73a provided on the peripheral surface of the toothed roller 72 are visible when the toothed roller 72 is viewed in the axial direction AX. In this embodiment, the value of the tooth pitch Pt of the wheel 73 is adjusted (set) so that the tie-bar cut portions 73b of the six wheels 73 are provided at regular intervals in the circumferential direction and the teeth 73a are provided on the peripheral surface of the toothed roller 72 at a constant pitch Pr (see
shift amount Tc=(N×Pt)+Pr
“N” is a multiple of Pt. “Pr” is defined by Pt/(number of wheels). The tooth pitch Pt of this embodiment is 3.6°, provided that “N” is “4”. In this case, the pitch Pr is 0.6° based on the expression of 3.6/6.
In this embodiment, the wheels 73 adjacent to each other in the axial direction AX are shifted from each other by the shift amount Tc by assembling the holders 74 adjacent to each other in the axial direction AX. Specifically, in a single holder 74 illustrated in
Operations of the toothed roller 72 (correction driving roller 70) having the above-mentioned configuration are described with reference to
As illustrated in
As described above, the toothed roller 200 has a distorted shape that differs from a perfect circle when the toothed roller 200 of the comparative example is viewed in the axial direction AX. Thus, when the toothed roller 200 of the comparative example transports the paper sheet P (see
In this respect, in the toothed roller 72 of this embodiment, as illustrated in
Next, a method for manufacturing the correction driving roller 70, which is an example of a method for manufacturing a roller, is described with reference to
As illustrated in
In the wheel preparing step, the plurality of wheel formed products 101 are formed by punching (press working) from the hoop material 100 illustrated in
In the holder/wheel assembling step, as illustrated in
In the holder assembling step, as illustrated in
In the driving shaft assembling step, as illustrated in
According to this embodiment, the following advantages can be obtained.
(1) The plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed roller 72 are not distributed unevenly in the circumferential direction when the toothed roller 72 is viewed in the axial direction AX, thereby being capable of reducing the occurrence of a case in which the shape of the toothed roller 72 differs from a perfect circle when the toothed roller 72 is viewed in the axial direction AX. Thus, the decrease in the transport accuracy of the paper sheet P to be transported by the toothed roller 72 (correction roller pair 60) can be suppressed.
(2) The plurality of tie-bar cut portions 73b are provided so that the first distance by which the tie-bar cut portions 73b are present contiguously along the circumferential direction of the toothed roller 72 is equal to or larger than the third distance obtained by dividing the total circumferential distance of the wheel 73 by the number of tie-bar cut portions 73b, and the second distance by which the tie-bar cut portions 73b are not present contiguously along the circumferential direction of the toothed roller 72 is smaller than the third distance. According to this configuration, the plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed roller 72 are not distributed unevenly in the circumferential direction when the toothed roller 72 is viewed in the axial direction AX. Thus, the decrease in the transport accuracy of the paper sheet P to be transported by the toothed roller 72 (correction roller pair 60) can be suppressed.
In particular, in this embodiment, the plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed roller 72 are arranged at a constant pitch in the circumferential direction when the toothed roller 72 is viewed in the axial direction AX. That is, the second distance equals “0”. Therefore, the shape of the toothed roller 72 is even closer to a perfect circle. Thus, the decrease in the transport accuracy of the paper sheet P to be transported by the toothed roller 72 can further be suppressed.
(3) The plurality of toothed rollers 72 that are reduced in terms of the occurrence of the case in which the shapes of the toothed rollers 72 differ from a perfect circle when the toothed rollers 72 are viewed in the axial direction AX are fixed to the driving shaft 71 while being arrayed in the axial direction AX (width direction X). According to this configuration, when the plurality of toothed rollers 72 fixed to the driving shaft 71 transport the paper sheet P, the variation in the transport accuracy of the paper sheet P in the width direction X of the paper sheet P along the axial direction of the driving shaft 71 can be suppressed.
(4) The teeth 73a of the wheels 73 of the toothed roller 72 are arranged so as to be positionally shifted from each other in the circumferential direction of the toothed roller 72 when the toothed roller 72 is viewed in the axial direction AX. This configuration reduces a risk that the leading edge of the paper sheet P that abuts the toothed roller 72 may enter the space between the teeth 73a on the peripheral surface of the toothed roller 72 compared with a configuration assumed such that the teeth 73a are provided on the peripheral surface of the toothed roller 72 so as to be arrayed linearly in the axial direction AX (width direction X) when the toothed roller 72 is viewed in the axial direction AX. Therefore, the decrease in the transport accuracy of the paper sheet P can be suppressed.
(5) The reduction in the occurrence of the case in which the shapes of the toothed rollers 72 which the leading edge of the paper sheet P abuts differ from a perfect circle when the toothed rollers 72 are viewed in the axial direction AX leads to a reduction in the occurrence of a case in which the position of the leading edge of the paper sheet P in the transport direction Y, which abuts the toothed roller 72, varies in the width direction X. Thus, the correction roller pair 60 (correction driving roller 70) including the toothed rollers 72 can accurately correct the skew feed of the paper sheet P.
A printing apparatus 10 of a second embodiment is described with reference to
As illustrated in
In the toothed roller 72 (see
Accordingly, advantages similar to the advantages of the first embodiment can be obtained.
The embodiments described above may be modified as in the following modified examples. The embodiments and the modified examples may be combined arbitrarily.
In the first embodiment, the tie-bar cut portions 73b adjacent to each other in the axial direction AX need not be arranged at regular intervals in the circumferential direction over the entire periphery of the wheel 73 when the toothed roller 72 is viewed in the axial direction AX. Specifically, the shift amount Tc may have such a value that 360° is not exactly divisible in a mathematical expression represented by shift amount Tc=360°/(number of tie-bar cut portions 73b×number of wheels 73). As an example thereof, when the number of wheels 73 is seven, the shift amount Tc is 12.8° with a remainder of 1.6° based on the expression of 360/(4×7). Therefore, the shift amount Tc of the six wheels 73 is set to 12.8°, and the shift amount Tc of the remaining one wheel 73 is set to 14.4° (=12.8+1.6). Also in this case, the plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed roller 72 are not distributed unevenly in the circumferential direction when the toothed roller 72 is viewed in the axial direction AX.
Further, the shift amount Tc of a plurality of wheels 73 may be set different from the shift amount Tc of the other wheels 73 instead of the case in which the shift amount Tc of one wheel 73 is set different from the shift amount Tc of the other wheels 73. For example, the shift amount Tc of the five wheels 73 is set to 12.8°, and the shift amount Tc of the remaining two wheels 73 is set to 13.6° (=12.8+1.6/2). Thus, the number of tie-bar cut portions 73b which are not arranged at regular intervals in the circumferential direction of the wheel 73 increases, but the amount of deviation between the positions of the tie-bar cut portions 73b which are arranged at regular intervals in the circumferential direction and the positions of the tie-bar cut portions 73b which are not arranged at regular intervals in the circumferential direction decreases.
In the embodiments described above, the roller other than the correction driving roller 70 may also be constructed such that the plurality of wheels 73 and the plurality of holders 74 are assembled as in the toothed roller 72. In this case, as illustrated in
In the embodiments described above, the shapes for achieving the fitting between the wheel 73 and the holder 74 may be changed. As an example, as illustrated in
In the embodiments described above, the teeth 73a of the wheels 73 of the toothed roller 72 need not be arranged while being shifted from each other so that all the teeth 73a become visible on the peripheral surface of the toothed roller 72 when the toothed roller 72 is viewed in the axial direction AX. For example, the teeth 73a of a predetermined wheel 73 may be arranged so as to completely overlap the teeth 73a of another wheel 73.
In the embodiments described above, the number of tie-bar cut portions 73b may be set arbitrarily.
It is preferred that the number of tie-bar portions 102 be equal to or larger than three so that the wheel formed products 101 are held on the hoop material 100 with good balance. Therefore, it is preferred that the number of tie-bar cut portions 73b be equal to or larger than three.
In the embodiments described above, in order that the tie-bar cut portions 73b of the plurality of toothed rollers 72 arrayed in the axial direction AX (width direction X) are not distributed unevenly, the positions of the plurality of toothed rollers 72 in the circumferential direction may be adjusted (set). For example, when the tie-bar cut portions 73b adjacent to each other in the axial direction AX on the ten toothed rollers 72 are shifted from each other in the circumferential direction of the toothed rollers 72 by 15° as in the first embodiment, the positions of the adjacent toothed rollers 72 in the circumferential direction are adjusted (set) so as to be shifted from each other by 1.5°. In short, the shift amount of the adjacent toothed rollers 72 in the circumferential direction is adjusted (set) to a value obtained by dividing the shift amount Tc of the tie-bar cut portions 73b of a single toothed roller 72 by the number of toothed rollers 72. According to this configuration, the occurrence of the case in which the tie-bar cut portions 73b overlap each other in the axial direction AX (width direction X) is also reduced between the plurality of toothed rollers 72 arrayed in the axial direction AX (width direction X). Thus, the decrease in the transport accuracy of the paper sheet P can further be suppressed.
In the embodiments described above, the plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed roller 72 need not be provided over the entire periphery when the toothed roller 72 is viewed in the axial direction AX. That is, a region where the tie-bar cut portions 73b are not present contiguously along the circumferential direction of the toothed roller 72 may be formed when the toothed roller 72 is viewed in the axial direction AX. In this case, the circumferential distance of the region where the tie-bar cut portions 73b are not present contiguously along the circumferential direction of the toothed roller 72 (second distance) is smaller than the third distance obtained by dividing the total circumferential distance of the wheel 73 by the number of tie-bar cut portions 73b. In short, it is only necessary to satisfy the relationships that the first distance by which the tie-bar cut portions 73b are present contiguously along the circumferential direction of the toothed roller 72 is equal to or larger than the third distance, and the second distance by which the tie-bar cut portions 73b are not present contiguously along the circumferential direction of the toothed roller 72 is smaller than the third distance.
In the embodiments described above, the number of toothed rollers 72 may be set arbitrarily. In short, the correction driving roller 70 only needs to have at least one toothed roller 72.
In the embodiments described above, some of the plurality of toothed rollers 72 of the correction driving roller 70 may be provided so that the plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed rollers 72 are distributed unevenly when the toothed rollers 72 are viewed in the axial direction AX. That is, at least one of the plurality of toothed rollers 72 of the correction driving roller 70 only needs to be provided so that the plurality of tie-bar cut portions 73b that are present along the circumferential direction of the toothed roller 72 are not distributed unevenly when the toothed roller 72 is viewed in the axial direction AX. In other words, at least one toothed roller 72 of the correction driving roller 70 only needs to satisfy the relationships that the first distance by which the tie-bar cut portions 73b are present contiguously along the circumferential direction of the toothed roller 72 is equal to or larger than the third distance, and the second distance by which the tie-bar cut portions 73b are not present contiguously along the circumferential direction of the toothed roller 72 is smaller than the third distance.
In the embodiments described above, the printing apparatus 10 is not limited to the configuration having the printing function alone, and may be a multifunction peripheral.
In the embodiments described above, the printing section 12 may be a serial head that is movable along the width direction X.
In the embodiments described above, the medium to be subjected to printing by the printing section 12 is not limited to a sheet of paper such as the paper sheet P, and may be continuous paper, a resin film, metal foil, a metal film, a composite film (laminated film) of resin and metal, woven fabric, nonwoven fabric, a ceramic sheet, or the like.
In the embodiments described above, a support table that supports the paper sheet P may be provided in place of the transport belt 38 facing the printing section 12.
The recording agent to be used for printing may be a fluid other than ink (a liquid, a liquid-like substance obtained by dispersing or mixing particles of functional materials in a liquid, a fluid-like substance such as a gel, or a substance containing a solid that is ejectable as a fluid). For example, printing may be performed by ejecting a liquid-like substance containing a dispersed or dissolved material such as an electrode material or a color material (pixel material) to be used for manufacturing liquid crystal displays, electroluminescence (EL) displays, and surface-emitting displays.
The printing apparatus 10 may be a fluid-like substance ejecting apparatus that ejects a fluid-like substance such as a gel (for example, a physical gel), or a granular substance ejecting apparatus (for example, a toner jet recording apparatus) that ejects a solid as typified by powder (granular substance) such as toner. Herein, the “fluid” is a concept which excludes a fluid composed of gas alone, and encompasses, for example, a liquid (including an inorganic solvent, an organic solvent, a solution, a liquid resin, and a liquid metal (molten metal)), a liquid-like substance, a fluid-like substance, and a granular substance (including granules and powder).
The printing apparatus 10 is not limited to the apparatus that performs printing on a medium such as the paper sheet P by directly ejecting liquid onto the medium, and may be an apparatus that performs planographic printing, relief printing, intaglio printing, screen printing, or the like, in which liquid applied to a printing plate is transferred onto a medium.
As explained above, a printing apparatus according to an aspect of the invention includes a transport roller that transports a medium. The transport roller includes a shaft that extends in a direction intersecting a transport direction of the medium, and a wheel group in which a plurality of toothed wheels arrayed in the direction in which the shaft extends are held by holders. The toothed wheel includes non-formation portions having no teeth. The non-formation portions of the plurality of toothed wheels of the wheel group are arranged with a phase difference therebetween in a circumferential direction of the toothed wheels.
This configuration reduces the occurrence of a case in which the shape of the wheel group to be brought into contact with the medium differs from a perfect circle when the wheel group is viewed in an axial direction. Thus, the medium can be transported stably.
In the printing apparatus, the non-formation portions may be cut portions that are formed when the toothed wheel is cut off from a base.
According to this configuration, a toothed wheel having high shape precision can be manufactured.
In the printing apparatus, the teeth other than the teeth adjacent to the cut portions may be arranged away from each other at regular intervals in a circumferential direction of the wheel group.
According to this configuration, a transport force can uniformly be transferred to the medium compared with a configuration in which the teeth are provided on the peripheral surface of the wheel group so as to be arrayed linearly in the axial direction when the wheel group is viewed in the direction intersecting the transport direction of the medium. Therefore, the decrease in the transport accuracy of the medium can be suppressed.
In the printing apparatus, the wheel group may satisfy the following relationships between a first distance, a second distance, and a third distance, which are measured when the wheel group is viewed in the direction intersecting the transport direction: first distance third distance and second distance<third distance. In the expression, the first distance is a cumulative distance of arcs in a state in which a plurality of the cut portions are present within a range of each of the arcs when the arcs are arranged without overlapping each other along a circumference of an imaginary circle connecting vertices of the teeth of the toothed wheel. The arcs each have a predetermined central angle along the circumference. The second distance is a cumulative distance of the arcs in a state in which a plurality of the cut portions are not present within the range of each of the arcs when the arcs are arranged without overlapping each other along the circumference. The third distance is a distance obtained by dividing a total circumferential distance of the toothed wheel by the number of the cut portions of one of the toothed wheels.
According to this configuration, the first distance is equal to or larger than the third distance and the second distance is smaller than the third distance, thereby being capable of reducing the occurrence of a case in which the cut portions are distributed unevenly in the circumferential direction of the wheel group when the wheel group is viewed in the direction intersecting the transport direction of the medium. Thus, the decrease in the transport accuracy of the medium to be transported by the roller can be suppressed.
In the printing apparatus, the wheel group may include six toothed wheels as the toothed wheels, and that, when four cut portions are provided with a phase difference of 90° as the cut portions of each of the toothed wheels, the central angle of the arc be 30°.
This configuration can reduce the occurrence of the case in which the cut portions are distributed unevenly in the circumferential direction of the wheel group when the wheel group is viewed in the axial direction. Thus, the decrease in the transport accuracy of the medium to be transported by the roller can be suppressed.
In the printing apparatus, the non-formation portions may be arranged away from each other at regular intervals in a circumferential direction of the wheel group.
According to this configuration, the cut portions are not distributed unevenly in the circumferential direction of the wheel group when the wheel group is viewed in the direction intersecting the transport direction of the medium. Thus, the decrease in the transport accuracy of the medium to be transported by the roller can be suppressed.
In the printing apparatus, the toothed wheel may include a wheel through hole through which the shaft extends, and a wheel projection that extends from a peripheral edge of the wheel through hole toward a center of an imaginary circle connecting vertices of the teeth of the toothed wheel. Further, the holder may include a through hole through which the shaft extends, a boss that is formed on one side surface of the holder so as to be located on an inner side with respect to an outer periphery defined by an edge of the holder in a circumferential direction thereof and so as to extend in the direction intersecting the transport direction, a recess that is formed on the one side surface of the holder so as to be recessed inward from the outer periphery side in the boss and so as to be engaged with the wheel projection, a surface that is formed on the one side surface of the holder so as to be located on the outer periphery side with respect to the boss and so as to support a side surface of a first toothed wheel, a depression that is formed on another side surface of the holder so as to be located on an inner side with respect to the outer periphery and so as to be depressed in the direction intersecting the transport direction for engagement with the boss of another holder, a projection that is formed on the another side surface of the holder so as to extend from the depression on the inner side toward a center of the outer periphery and so as to be engaged with the recess of another holder in a state in which the wheel projection of a second toothed wheel different from the first toothed wheel is engaged with the recess, and a surface that is formed on the another side surface of the holder so as to be located on the outer periphery side with respect to the depression and so as to support a side surface of the second toothed wheel. Further, the projection and the recess of one of the holders may be formed with a phase difference therebetween in the circumferential direction of the holder when the holder is viewed in the direction intersecting the transport direction.
This configuration can facilitate the assembling of a wheel group having the cut portions shifted from each other in the circumferential direction of the wheel group when the wheel group is viewed in the direction intersecting the transport direction of the medium.
In the printing apparatus, the transport roller may be constructed such that a plurality of the wheel groups are fixed to the shaft while being arrayed along the shaft.
According to this configuration, a registration roller that uses the toothed wheels can be manufactured simply while facilitating quality control of the registration roller. Moreover, when the plurality of wheel groups fixed to the rotary shaft transport the medium, a variation in the transport accuracy of the medium in a width direction of the medium in the axial direction of the rotary shaft can be suppressed.
The printing apparatus may be an ink jet printing apparatus, and that the transport roller may be a registration roller that corrects skew feed of the medium.
This configuration reduces the occurrence of a case in which the position of the medium in the transport direction, which abuts the wheel group, varies in the width direction of the medium, which is the direction intersecting the transport direction of the medium. Thus, the registration roller can accurately correct the skew feed of the medium. Moreover, by employing this registration roller in the ink jet printing apparatus, transfer of ink onto the registration roller can be reduced. Particularly in duplex printing, when printing is performed on a first surface and then on a second surface opposite the first surface by reversing the medium, the first surface subjected to printing faces the registration roller, and as a result, undried ink is susceptible to being transferred onto the registration roller. The contact area of the toothed roller is smaller than that of general registration rollers, and as a result, the transfer of ink onto the registration roller can be reduced.
Number | Date | Country | Kind |
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2016-045577 | Mar 2016 | JP | national |
This application is a continuation application of U.S. patent application Ser. No. 15/447,647 filed on Mar. 2, 2017. This application claims priority to Japanese Patent Application No. 2016-045577 filed on Mar. 9, 2016. The entire disclosures of U.S. patent application Ser. No. 15/447,647 and Japanese Patent Application No. 2016-045577 are expressly incorporated herein by reference.
Number | Date | Country | |
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Parent | 15447647 | Mar 2017 | US |
Child | 16024987 | US |