Patent Application
20090267284
1. Technical Field
The present invention relates to a transport device which transports a sheet-like medium, and an image recording apparatus.
2. Related Art
For example, image recording apparatuses, such as a printer, include a transport device which transports a sheet-like medium arranged in the tray to an image recording unit. An example of a technique concerning an image recording apparatus provided with a transport device including a transport path called a U-turn path is disclosed in JP-A-2006-008328 and JP-A-2007-182264
When a sheet-like medium is transported and transport resistance is large, for example, a transport speed may become unstable or the sheet-like medium may stop. As a result, the sheet-like medium cannot be transported well to the recording unit, and the quality of an image to be formed on the sheet-like medium may deteriorate.
An advantage of some aspects of the invention is that it provides a transport device which can transport a sheet-like medium well. Additionally, another advantage of some aspects of the invention is that it provides an image recording apparatus which can record an image on a sheet-like medium well.
According to a first aspect of the invention, a transport device includes: a transport path which connects an inlet and an outlet and is formed between a first curved surface which is convex in a first direction, and a second curved surface which faces the first curved surface via a gap, and along which a sheet-like medium is transported; a protruding portion which is arranged on the first curved surface and protrudes from the first curved surface; and a first roller which is arranged on the second curved surface, and at least a portion of which protrudes from the second curved surface. The protruding portion is arranged in a position where the sheet-like medium which has entered the transport path through the inlet contacts the protruding portion prior to the first roller.
According to the first aspect of the invention, after the sheet-like medium which has entered the transport path through the inlet of the transport path formed between the first curved surface and the second curved surface has contacted the protruding portion arranged on the first curved surface, the sheet-like medium contacts the first roller of the second curved surface, and is transported toward the outlet. Thereby, an increase in the transport resistance of the sheet-like medium when being moved along the transport path can be suppressed. Accordingly, the sheet-like medium can be transported well.
In the first aspect of the invention, the protruding portion is arranged in a position closer to the inlet than the first roller, and adjusts the plunging angle of a leading edge of the sheet-like medium with respect to the first roller. Since the sheet-like medium which has entered the transport path through the inlet contacts the protruding portion before contacting the first roller, the posture of the sheet-like medium is adjusted, and the plunging angle of the leading edge of the sheet-like medium with respect to the first roller is adjusted. The plunging angle of the leading edge of the sheet-like medium with respect to the first roller is an angle formed by the traveling direction of the sheet-like medium, and a line perpendicular to a tangential line of the first roller in a position where the leading edge of the sheet-like medium, and the first roller collide with each other. Transport resistance changes according to the plunging angle of the leading edge of the sheet-like medium with respect to the first roller. Accordingly, an increase in the transport resistance can be suppressed by the protruding portion of the first curved surface which can adjust the plunging angle of the leading edge of the sheet-like medium with respect to the first roller.
In the first aspect of the invention, the first roller is arranged in the vicinity of an apex of the second curved surface. Thereby, after the sheet-like medium which has entered the transport path through the inlet has contacted the protruding portion, the sheet-like medium contacts the first roller, and is transported well to the outlet.
In the first aspect of the invention, the protruding portion includes at least a portion of the second roller. Thereby, since the sheet-like medium which has entered the transport path through the inlet contacts the rotatable second roller, an increase in transport resistance is suppressed.
In the first aspect of the invention, the external diameter of the second roller is smaller than the external diameter of the first roller. Thereby, enlargement of the transport device can be suppressed.
In the first aspect of the invention, the transport path is adapted such that the sheet-like medium one face of which faces a second direction is curved in the inlet, and the one face faces a direction substantially opposite to the second direction in the outlet. That is, enlargement of the transport device can be suppressed by forming the transport path as a U-turn path (reversing path).
According to a second aspect of the invention, an image recording apparatus includes: a tray in which a sheet-like medium is arranged; a recording unit which is arranged in a position different from the tray, and records an image on the sheet-like medium; and the transport device of the first aspect which transports the sheet-like medium of the tray to the recording unit.
According to the second aspect of the invention, the sheet-like medium arranged in the tray is made to enter the transport path through the inlet of the transport device of the first aspect. Thus, while an increase in transport resistance is suppressed, the sheet-like medium can be taken out of the outlet, and transported to the recording unit well. Accordingly, an image can be recorded on the sheet-like medium well by the recording unit.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Hereinafter, embodiments of the invention will be described with reference to the drawings. In the following description, an XYZ orthogonal coordinate system will be set, and the positional relationship of respective members will be described with reference to this XYZ orthogonal coordinate system. A predetermined direction within a horizontal plane is defined as an X-axis direction, a direction orthogonal to the X-axis direction in the horizontal plane is defined as a Y-axis direction, and a direction orthogonal to both the X-axis direction and the Y-axis direction (that is, a perpendicular direction) is defined as a Z-axis direction.
In
The recording unit 5 includes a recording head 2 which ejects ink, a carriage 7 which is movable while supporting the recording head 2, and a platen 8 which is arranged in a position which faces the recording head 2 supported by the carriage 7, and supports the recording paper P onto which ink is to be ejected.
The ink jet printer 1 includes a carriage guide member 9 which guides movement of the carriage 7, and a carriage driving unit 10 including a timing belt and a motor which drives the timing belt. The carriage 7 is moved in a main scanning direction (X-axis direction) by the carriage driving unit 10 while being guided by the carriage guide member 9. The recording paper P is moved in a sub-scanning direction (Y-axis direction) which intersects the main scanning direction (X-axis direction) with respect to the recording unit 5 by the recording paper transport device 6.
In this embodiment, the recording head 2 is a so-called electromechanical conversion type droplet discharge head. The recording head 2 has a piezoelectric element and a space the pressure of which changes by the deformation of the piezoelectric element. The space is formed by a flexible film displaced by the deformation of the piezoelectric element, a plate (nozzle plate) having an ejection port 3, etc. Ink is reserved in the space. When a pulsatile electric signal is supplied to the piezoelectric element, the piezoelectric element is deformed on the basis of the electric signal. When the flexible film is displaced by the deformation of the piezoelectric element, the pressure of the space in which ink is reserved changes. Some of the ink in the space is ejected (discharged) from the ejection port 3 by the change of the pressure.
The recording head 2 includes an ejection face 11 in which the ejection port 3 which ejects ink is formed. The ejection port 3 is able to discharge droplets of ink. In this embodiment, the ejection face 11 is nearly parallel to an XY plane. Additionally, in this embodiment, the ejection face 11 is a rectangle which is long in the X-axis direction. A plurality of the ejection ports 3 is formed at predetermined intervals, for example, in the X axis in the ejection face 11.
The platen 8 of the recording unit 5 is arranged in the position which faces the ejection face 11 of the recording head 2 supported by the carriage 7, and supports one face Pa of the recording paper P arranged in the recording unit 5. The recording head 2 and the carriage 7 are arranged above (+Z side) the platen 8.
The recording paper transport device 6 transports the recording paper P in the sub-scanning direction (Y-axis direction) with respect to the recording unit 5 in an interlocking manner with the recording operation by the recording unit 5. The recording paper transport device 6 includes a paper feed roller 12 for carrying out the recording paper P of the paper feed tray 4, a paper feed roller driving unit 13 including a motor which drives the paper feed roller 12, a recording paper guide member 14 which guides movement of the recording paper P, a transport roller 15 which is arranged on the downstream side in a transport direction with respect to the paper feed roller 12 and the recording paper guide member 14, a transport roller driving unit 16 including a motor which drives the transport roller 15, a pinch roller 17 which is arranged in a position which faces the transport roller 15, a discharge roller 18 which is arranged on the downstream side in the transport direction with respect to the transport roller 15 and the recording unit 5, a discharge roller driving unit 19 including a motor which drives the discharge roller 18, and a spur roller 20 which is arranged in the position which faces the discharge roller 18.
The paper feed roller 12 is arranged in a position which faces the recording paper P arranged in the paper feed tray 4. The paper feed roller 12 is able to pick up the recording paper P arranged on the uppermost side (+Z side) among a plurality of recording papers P stacked in the paper feed tray 4, and carry out the recording paper from the paper feed tray 4. The recording paper P of the paper feed tray 4 is fed to between the transport roller 15 and the pinch roller 17 by the paper feed roller 12 which is driven by the paper feed roller driving unit 13 while being guided by the recording paper guide member 14. The transport roller 15 is able to pinch a recording paper between the transport roller and the pinch roller 17. The pinch roller 17 is a driven roller which is rotated so as to follow the driving of the transport roller 15. The recording paper P fed to between the transport roller 15 and the pinch roller 17 is fed to between the discharge roller 18 and the spur roller 20 via the recording unit 5 arranged on the downstream side in the transport direction by the transport roller 15 which is driven by the transport roller driving unit 16. The discharge roller 18 is able to pinch the recording paper P between the discharge roller and the spur roller 20. The spur roller 20 is a driven roller which is rotated so as to follow the driving of the discharge roller 18. The recording paper P recorded by the recording unit 5 is discharged from the ink jet printer 1 by the recording paper transport device 6 including the discharge roller 18.
The recording paper guide member 14 forms a transport path 21 along which the recording paper P is transported. Additionally, the recording paper guide member 14 forms an inlet 22 and an outlet 23 of the transport path 21. The inlet 22 is arranged at a lower end of the guide member 14, and the outlet 23 is arranged at an upper end of the guide member 14. In this embodiment, the paper feed tray 4 is arranged on the −Z side of the recording unit 5. The inlet 22 is arranged in the vicinity of the paper feed tray 4, and the outlet 23 is arranged in the vicinity of the recording unit 5.
The transport path 21 is formed so as to connect the inlet 22 and the outlet 23. The recording paper P from the paper feed tray 4 enters the transport path 21 through the inlet 22. After the recording paper P which has entered the transport path 21 through the inlet 22 has been transported along the transport path 21, the recording paper comes out from an outlet 23 and is fed to the recording unit 5.
The transport path 21 is formed between a first curved surface 24 which is convex in the +Y direction, and a second curved surface 25 which faces the first curved surface 24 via a gap G. In this embodiment, the recording paper guide member 14 includes a first guide member 14A in which the first curved surface 24 is arranged, and a second guide member 14B in which the second curved surface 25 is arranged. In this embodiment, each of the first guide member 14A and the second guide member 14B is a plate member which is convexly curved toward +Y direction. In this embodiment, in a cross-section parallel to the YZ plane, each of the first curved surface 24 and the second curved surface 25 has a circular-arc shape which is convex in the +Y direction. In this embodiment, the transport path 21 formed between the first guide member 14A and the second guide member 14B includes a so-called U-turn path (reversing path).
In this embodiment, the recording paper P is arranged in the paper feed tray 4 with one face Pa turned toward the +Z side. The paper feed roller 12 is arranged in a position which faces one face Pa of the recording paper P arranged in the paper feed tray 4. The paper feed roller 12 picks up the recording paper P arranged on the uppermost side (+Z side) among a plurality of recording papers P stacked in the paper feed tray 4, and carries out the recording paper from the paper feed tray 4.
In this embodiment, a separating inclined plate 26 is arranged between the paper feed tray 4 (paper feed roller 12) and the inlet 22 of the transport path 21. The separating inclined plate 26 separates a plurality of recording papers P overlappingly fed from the paper feed tray 4, for example, by the paper feed roller 12, and guides the recording paper P, which is arranged on the uppermost side (+Z side) among a plurality of recording papers P stacked in the paper feed tray 4, to the inlet 22.
The transport path 21 includes a first portion 21A which inclines toward +Y direction with respect to the Z axis through the inlet 22, a second portion 21B which is bent to the +Z side gradually from an upper end of the first portion 21A, a third portion 21C which extends in the +Z direction from an upper end of the second portion 21B, a fourth portion 21D which is bent to the −Y side gradually from an upper end of the third portion 21C, and a fifth portion 21E which inclines toward the −Y direction with respect to the Z axis from an upper end of the fourth portion 21D. The recording paper P which has entered the transport path 21 through the inlet 22 is transported to the outlet 23 while being curved in the transport path 21 including the first to fifth portions 21A to 21E.
In this embodiment, the transport roller 15 and the pickup roller 17 are arranged between the outlet 23 of the transport path 21, and the recording unit 5. Additionally, in this embodiment, a pair of plate members 27 and 28 is arranged between the outlet 23 of the transport path 21, and the transport roller 15 and the pickup roller 17. The thickness of the plate members 27 and 28 is smaller than the thickness of the first and second guide members 14A and 14B. The transport path 29 along which the recording paper P is transported is formed between the plate member 27 and the plate member 28. The plate members 27 and 28 guide the recording paper P which has come out of the outlet 23 to between the transport roller 15 and the pickup roller 17.
The recording paper P which has passed between the transport roller 15 and the pickup roller 17 is fed to between the recording head 2 of the recording unit 5, and the platen 8. The recording head 2 is arranged above (+Z side) the platen 8, one face Pa of the recording paper P fed to the recording unit 5 faces the platen 8, and the other face of the recording paper faces the recording head 2. As such, in this embodiment, the transport path 21 forms the U-turn path (reversing path) in which the recording paper P one face Pa of which faces +Z direction is curved in the vicinity of the paper feed tray 4 and the inlet 22, and one face Pa faces −Z direction in the vicinity of the outlet 23 and in the recording unit 5.
The first curved surface 24 forms an inside surface of the curved transport path 21, and the second curved surface 25 forms an outside surface of the curved transport path 21. In the following description, the first curved surface 24 is appropriately referred to as an inside curved surface 24, and the second curved surface 25 is appropriately referred to as an outside curved surface 25. Additionally, the first guide member 14A is appropriately referred to as an inside guide member 14A, and the second guide member 14B is appropriately referred to as an outside guide member 14B.
In this embodiment, the recording paper transport device 6 includes the protruding portion 30 which is arranged on the inside curved surface 24 and protrudes from the inside curved surface 24, and an outside roller 31 which is arranged on the outside curved surface 25, and at least a portion of which protrudes from the outside curved surface 25.
In this embodiment, the protruding portion 30 includes at least a portion of the inside roller 32 rotatably supported by the inside guide member 14A. In this embodiment, at least a portion of the inside roller 32 protrudes toward the transport path 21 (outward) from the inside curved surface 24.
The outside roller 31 is rotatably supported by the outside guide member 14B. At least a portion of the outside roller 31 protrudes toward the transport path 21 (inward) from the outside curved surface 25.
In this embodiment, the protruding portion 30 is arranged in a position where the recording paper P which has entered the transport path 21 through the inlet 22 contacts the protruding portion prior to the outside roller 31.
Additionally, in this embodiment, a plurality of inside rollers 33 (33A, 33B) is arranged in the inside curved surface 24 on the downstream side in the transport direction with respect to the protruding portion 30.
The inside guide member 14A includes a plurality of openings 34A, 34B, and 34C in which the inside rollers 32, 33A, and 33B are arranged, respectively, and supporting portions 35A, 35B, and 35C which are arranged at edges of the openings 34A, 34B, and 34C, and rotatably support the inside rollers 32, 33A, and 33B, respectively. The supporting portions 35A, 35B, and 35C supports the inside rollers 32, 33A, and 33B, respectively, so as to be rotatable around the X axis. In this embodiment, the inside rollers 32, 33A, and 33B are arranged roughly in the middle of the transport path 21 in the width direction (X-axis direction) so as to stand in a line in the transport direction (Z-axis direction in
In this embodiment, the inside roller 32 which forms the protruding portion 30 is arranged in a position closer to the inlet 22 than the outside roller 31. In this embodiment, the inside roller 32 which forms the protruding portion 30 is arranged so as to face the second portion 21B (or the first portion 21A) of the transport path 21. The inside roller 33A is arranged so as to face the third portion 21C of the transport path 21. The inside roller 33B is arranged so as to face the fourth portion 21D (or the fifth portion 21E) of the transport path 21.
In this embodiment, the outside roller 31 includes two outside rollers 31A and 31B arranged in the width direction (X-axis direction) of the transport path 21. The outside guide member 14B includes a plurality of openings 36A and 36B in which the outside rollers 31A and 31B are arranged, respectively, and supporting portions 37A and 37B which are arranged at edges of the openings 36A and 36B, and rotatably support the outside rollers 31A and 31B, respectively. The supporting portions 37A and 37B support the outside rollers 31A and 31B, respectively, so as to be rotatable around the X axis. In this embodiment, the outside rollers 31A and 31B are arranged on both sides of the inside roller 33A in the X-axis direction within the XZ plane.
In this embodiment, the outside roller 31 is arranged in a position closer to the outlet 23 than the protruding portion 30. In this embodiment, the outside roller 31 is arranged so as to face the third portion 21C of the transport path 21. That is, in this embodiment, the outside roller 31 is arranged in the vicinity of the apex of the second curved surface 25. The apex of the second curved surface 25 is a portion nearest to the +Y side within the YZ plane in the second curved surface 25, and includes an inflection point.
Additionally, in this embodiment, the size (external diameter) of the outside roller 31B is the same as the size (external diameter) of the outside roller 31A. Additionally, the size (external diameter) of the inside roller 32, the size (external diameter) of the inside roller 33A, and the size (external diameter) of the inside roller 33B are the same. Additionally, the sizes (external diameters) of the inside rollers 32, 33A, and 33B are smaller than the sizes (external diameters) of the outside rollers 31A and 31B.
Next, an example of the operation of the ink jet printer 1 will be described. In order to record an image on the recording paper P in ink, the recording paper P of the paper feed tray 4 is carried out of the paper feed tray 4 by the paper feed roller 12. The leading edge of the recording paper P carried out of the paper feed tray 4 enters the transport path 21 through the inlet 22 after it has contacted the separating inclined plate 26.
Additionally, as the recording paper P contacts the protruding portion 30, its posture is adjusted before contacting the outside roller 31. The protruding portion 30 is arranged in a position closer to the inlet 22 than the outside roller 31, and is able to adjust the posture of the recording paper P, which has entered the transport path 21 through the inlet 22, before contacting the outside roller 31.
In this embodiment, the protruding portion 30 adjusts the plunging angle θ of the leading edge of the recording paper P with respect to the outside roller 31. In this embodiment, the positional relationship between the outside roller 31 and the protruding portion 30 is adjusted (optimized) according to, for example, the basis weight of the recording paper P so that the leading edge of the recording paper P enters (plunges into) at a predetermined plunging angle θ with respect to the outside roller 31.
In this embodiment, the basis weight of the recording paper P is, for example, 50 to 300 g/m2. In addition, in a case where the frequency in use of recycled paper, photographic paper, etc. as the recording paper P is high, the basis weight of the recycled paper is about 50 g/m2 and the basis weight of the photographic paper is about 200 g/m2. Thus, the basis weight of the recording paper P with high use frequency is, for example, 50 to 200 g/m2. In this embodiment, the position of the protruding portion 30 with respect to the outside roller 31 is adjusted (optimized) according to the basis weight of the recording paper P so that the leading edge of the recording paper P enters (plunges into) at the predetermined plunging angle θ with respect to the outside roller 31.
In this embodiment, the positional relationship between the outside roller 31 and the protruding portion 30 is adjusted (optimized) according to the basis weight of the recording paper P so that the plunging angle θ of the leading edge of the recording paper P with respect to the outside roller 31 becomes, for example, 5 to 35 degrees, preferably, 10 to 30 degrees. If the plunging angle θ is large, the force which acts in the direction away from the outside roller 31 may occur in the recording paper P. As a result, for example, the recording paper P and the inside curved surface 24 may contact each other, and transport resistance may become large. On the other hand, if the plunging angle θ is small, for example, the leading edge of the recording paper P may be caught on the surface of the outside roller 31, and the recording paper P may not be transported well. By adjusting (optimizing) the positional relationship of the outside roller 31 and the protruding portion 30 (optimization) so that the plunging angle θ of the leading edge of the recording paper P with respect to the outside roller 31 becomes, for example, 5 to 35 degrees, preferably, 10 to 30 degrees, an increase in transport resistance can be suppressed, and the recording paper P can be transported well.
After contacting the protruding portion 30, the recording paper P which has contacted the outside roller 31 is transported along the transport path 21 while one face Pa and the inside rollers 33A and 33B are brought into contact with each other. In this embodiment, since the inside rollers 33A and 33B are arranged in addition to the inside roller 32, the recording paper transport device 6 is able to transport the recording paper P while damage of one face Pa of the recording paper P is suppressed. The leading edge of the recording paper P which has come of the outlet 23 of the transport path 21 is guided by the plate members 27 and 28, and is fed to between the transport roller 15 and the nip roller 17.
Then, as shown in
The recording paper transport device 6 transports the recording paper P in the sub-scanning direction (Y-axis direction) with respect to the recording unit 5 in an interlocking manner with the recording operation by the recording unit 5. The recording paper P on which an image has been recorded by the recording unit 5 is discharged from the ink jet printer 1.
As described above, according to this embodiment, the recording paper P which has entered the transport path 21 through the inlet 22 contacts the protruding portion 30 before it contacts the outside roller 31. Thus, an increase in the transport resistance of the recording paper P can be suppressed. Accordingly, the recording paper P is transported to the recording unit 5, and an image is recorded well in the recording unit 5.
Additionally, as one face Pa of the recording paper P and the protruding portion 30 whose surface is curved contacts each other, the recording paper transport device 6 is able to transport the recording paper P while suppressing damage of one face Pa of the recording paper P.
Additionally, the protruding portion 30 is arranged in a position closer to the inlet 22 of the transport path 21 than the outside roller 31, and is able to adjust the plunging angle θ of the leading edge of the recording paper P with respect to the outside roller 31. Accordingly, after the recording paper P contacts the outside roller 31, it is smoothly transported to the recording unit 5 via the outlet 23.
In addition, although the case where the protruding portion 30 is a portion of the rotatable inside roller 32 has been described as an example in the above-described embodiment, the protruding portion may be, for example, a convex portion formed integrally with the inside curved surface 24.
In addition, although the case where the recording paper transport device 6 is provided in the ink jet printer 1 which records an image on the recording paper P has been described as an example in the above-described embodiment, the paper transport device may be provided in image forming apparatuses, such as a copying machine and a facsimile, not limited to the ink jet printer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-102422 | Apr 2008 | JP | national |
