Conveying device

Abstract

To provide a conveying device capable of reducing or removing dust adhering to a detection unit that detects paper without providing an additional mechanism or member.SOLUTION: Vertical conveying rollers 23 convey the paper P. Registration rollers 31 are disposed downstream of the vertical conveying rollers 23 in the conveying direction of the paper P, and convey the paper P. The paper sensor 26 is disposed between the vertical conveying rollers 23 and the registration rollers 31, and detects the paper P. The control unit controls the vertical conveying rollers 23 and the registration rollers 31 to form and release slack in the paper P between the vertical conveying rollers 23 and the registration rollers 31 while the registration rollers 31 hold the paper P, thereby generating an airflow F that is blown toward the paper sensor 26.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a transport device that transports paper. [Background technology]

[0002] There is known a printing apparatus that prints on paper while transporting the paper. In such a printing apparatus, a sensor (detection unit) that detects the paper is disposed along the paper transport path in order to detect a paper jam or the like.

[0003] In such a printing device, paper dust (particles) generated during paper transport may adhere to and accumulate on the sensor. The accumulation of paper dust may cause the sensor to erroneously detect the paper. For this reason, some kind of measure must be taken, such as periodically cleaning the sensor.

[0004] In response to this, Patent Document 1 discloses a technique in which a sensor cleaning device is disposed inside the machine body in advance, and the sensor is cleaned by moving the cleaning device during cleaning.

[0005] Furthermore, Patent Document 2 discloses a technique for preventing paper dust from accumulating on the sensor by covering a hole provided in a guide plate of a paper transport path with a transparent film so that light from the sensor can pass through. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7134807 [Patent Document 2] Patent No. 4766520 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the technology of Patent Document 1, the sensor cleaning device is disposed inside the machine body, which leads to an increase in the size of the machine body and a complex configuration.

[0008] Furthermore, with the technology of Patent Document 2, if the film becomes dirty or rubbed and becomes cloudy, it is necessary to disassemble the camera body and replace the film.

[0009] For this reason, there was a demand for technology that could reduce or remove paper powder (dust) adhering to the sensor without providing additional mechanisms or components such as the cleaning device in the technology of Patent Document 1 mentioned above or the film in the technology of Patent Document 2.

[0010] The present invention has been made in consideration of the above, and aims to provide a conveying device that can reduce or remove dust that adheres to a detection section that detects paper without providing any additional mechanisms or components. [Means for solving the problem]

[0011] In order to achieve the above-mentioned object, the conveying device of the present invention is characterized in that it comprises a first conveying section that conveys paper, a second conveying section that is arranged downstream of the first conveying section in the paper conveying direction and conveys the paper, a detection section that is arranged between the first conveying section and the second conveying section and detects the paper, and a control section that controls the first conveying section and the second conveying section to generate an airflow to be blown toward the detection section by forming and releasing slack in the paper between the first conveying section and the second conveying section while the second conveying section holds the paper. Effect of the Invention

[0012] According to the conveying device of the present invention, dust adhering to the detection unit that detects the paper can be reduced or removed without providing any additional mechanism or member. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a printing device according to an embodiment. [Diagram 2] 2 is a control block diagram of the printing apparatus shown in FIG. 1. [Diagram 3] 11 is an explanatory diagram of a paper dust blowing operation. FIG. [Figure 4] 11 is an explanatory diagram of a paper dust blowing operation. FIG. [Diagram 5] 11 is an explanatory diagram of a paper dust blowing operation. FIG. [Figure 6] 11 is an explanatory diagram of a paper dust blowing operation. FIG. [Figure 7] 11 is an explanatory diagram of a paper dust blowing operation. FIG. [Figure 8] 11 is an explanatory diagram of a paper dust blowing operation. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts and components are denoted by the same or equivalent reference numerals throughout the drawings.

[0015] The following embodiments are examples of devices for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the material, shape, structure, arrangement, etc. of each component to those described below. The technical idea of ​​the present invention can be modified in various ways within the scope of the claims.

[0016] Fig. 1 is a schematic diagram of a printing device provided with a conveying device according to an embodiment of the present invention. Fig. 2 is a control block diagram of the printing device shown in Fig. 1. In the following description, the top, bottom, left, and right directions on the paper surface of Fig. 1 are defined as the top, bottom, left, and right directions.

[0017] 1 and 2, the printing device 1 according to the present embodiment includes a paper feed section 2, a printing transport section 3, a printing section 4, an upper transport section 5, a paper discharge section 6, an inversion section 7, an operation panel 8, a jam release door 9, and a control section 10. The sections of the printing device 1 other than the printing section 4 form a transport device.

[0018] The paper feed unit 2 feeds paper P (see FIG. 3, etc.) to the print transport unit 3. The paper feed unit 2 includes two external paper feed rollers 21, two internal paper feed rollers 22, a pair of vertical transport rollers 23, an external paper feed motor 24, an internal paper feed motor 25, and a paper sensor 26 (corresponding to a detection unit).

[0019] The external paper feed roller 21 picks up paper P one sheet at a time from an external paper feed tray (not shown) that is partially exposed outside the housing (not shown) of the printing device 1, and sends the paper P from the external paper feed tray to the external paper feed path RS1 that leads to the printing transport unit 3.

[0020] The internal paper feed roller 22 picks up paper P one sheet at a time from an internal paper feed tray (not shown) arranged inside the housing of the printing device 1, and sends the paper P from the internal paper feed tray to the internal paper feed path RS2 leading to the printing transport unit 3.

[0021] The pair of vertical transport rollers 23 nip the paper P taken out from the internal paper feed tray by the internal paper feed rollers 22 and transport the paper P along the internal paper feed path RS2 toward the registration rollers 31. The vertical transport rollers 23 are configured to be reversibly driven in order to transport the paper P in the opposite direction to that during paper feeding in a paper dust blowing operation described below for blowing away paper dust adhering to the paper sensor 26. That is, the vertical transport rollers 23 transport the paper P in the transport direction during paper feeding toward the registration rollers 31 by forward driving, and transport the paper P in the opposite direction by reverse driving.

[0022] The external paper feed motor 24 rotates and drives the external paper feed rollers 21 and the vertical transport rollers 23. The external paper feed motor 24 can be connected / disconnected to the external paper feed rollers 21 and the vertical transport rollers 23 via a clutch (not shown). The drive of the external paper feed rollers 21 and the vertical transport rollers 23 is switched by the clutch.

[0023] The internal paper feed motor 25 drives the internal paper feed roller 22 to rotate.

[0024] The paper sensor 26 detects the paper P transported from the external paper feed rollers 21 to the registration rollers 31, and the paper P transported from the vertical transport rollers 23 to the registration rollers 31. The paper sensor 26 is disposed at a position between the external paper feed rollers 21 and the registration rollers 31 in the transport direction of the paper P, and between the vertical transport rollers 23 and the registration rollers 31. The paper sensor 26 is a transmission type optical sensor having a light emitting portion 26a and a light receiving portion 26b, and is composed of an analog sensor that outputs a signal indicating the amount of light received by the light receiving portion 26b.

[0025] The light-emitting unit 26a emits light toward the upper left toward the external paper feed path RS1 and the internal paper feed path RS2. The light-receiving unit 26b receives the light emitted by the light-emitting unit 26a. The light-receiving unit 26b is disposed facing the light-emitting unit 26a and toward the lower right, with the external paper feed path RS1 and the internal paper feed path RS2 in between.

[0026] The print transport unit 3 transports the paper P transported from the paper feed unit 2 or the reversing unit 7. The print transport unit 3 includes a pair of registration rollers 31, a registration motor 32, a belt platen unit 33, a belt platen motor 34, pressure rollers 35 and 36, and a paper sensor 37 (corresponding to a detection unit).

[0027] The registration rollers 31 temporarily stop the paper P conveyed from the paper feed section 2 or the inversion section 7, and then nip and convey the paper P toward the belt platen section 33. The registration rollers 31 are configured to be reversely driven so as to convey the paper P in a paper dust blowing operation for blowing off paper dust adhering to a paper sensor 37 described later in a direction opposite to that during printing. That is, the registration rollers 31 convey the paper P in the conveying direction during printing toward the belt platen section 33 by forward driving, and convey the paper P in the opposite direction by reverse driving. The registration rollers 31 are disposed along the normal path RC near the downstream side of the junction of the external paper feed path RS1, the internal paper feed path RS2, and the inversion path RR in the conveying direction of the paper P. Therefore, the registration rollers 31 are disposed downstream of the external paper feed rollers 21 and the vertical conveying rollers 23.

[0028] Here, the normal path RC is a transport path for transporting the paper P from the paper feed unit 2 to the paper discharge unit 6 and the inversion unit 7. The inversion path RR is a transport path for inverting the paper P by the inversion unit 7 and re-feeding it to the print transport unit 3.

[0029] The registration motor 32 drives the registration rollers 31 to rotate.

[0030] The belt platen unit 33 transports the paper P transported from the registration rollers 31 along a horizontal portion in the upstream area of ​​the normal path RC. The belt platen unit 33 is disposed on the downstream side of the registration rollers 31. The belt platen unit 33 includes a transport belt 41, a drive roller 42, and driven rollers 43-45.

[0031] The conveyor belt 41 attracts and holds the paper P conveyed by the registration rollers 31 and conveys it. The conveyor belt 41 is a circular belt stretched around a drive roller 42 and driven rollers 43 to 45. The conveyor belt 41 has a large number of belt holes (not shown) formed therein as through holes for suctioning air. The conveyor belt 41 attracts and holds the paper P by the suction force generated in the belt holes by the drive of a fan (not shown). The conveyor belt 41 rotates (moves endlessly) in the clockwise direction in FIG. 1, thereby conveying the attracted and held paper P in a conveying direction from left to right.

[0032] The drive roller 42 rotates the conveyor belt 41 in the clockwise direction in FIG.

[0033] The driven rollers 43 to 45 support the conveyor belt 41 together with the drive roller 42. The driven rollers 43 to 45 rotate following the rotation of the conveyor belt 41. The driven roller 43 is disposed to the left of the drive roller 42 at the same height as the drive roller 42. The driven rollers 44 and 45 are disposed below the drive roller 42 and the driven roller 43, spaced apart from each other in the left-right direction, at the same height.

[0034] The belt platen motor 34 drives the drive roller 42 to rotate.

[0035] The pressure rollers 35 and 36 are rollers for pressing the paper P against the conveyor belt 41. The pressure rollers 35 and 36 are rotated by the rotating conveyor belt 41. The pressure rollers 35 and 36 are disposed above the driven roller 43 and the driving roller 42, respectively, at positions where they come into contact with the conveyor belt 41.

[0036] The paper sensor 37 detects the paper P being transported from the registration rollers 31 to the belt platen unit 33. The paper sensor 37 is disposed between the registration rollers 31 and the belt platen unit 33 in the transport direction of the paper P. The paper sensor 37 is an analog sensor similar to the paper sensor 26 described above, and has a light-emitting unit 37a and a light-receiving unit 37b.

[0037] The light-emitting unit 37a emits light upward along the normal path RC. The light-receiving unit 37b receives the light emitted by the light-emitting unit 37a. The light-receiving unit 37b is disposed facing downward and opposite the light-emitting unit 37a across the normal path RC.

[0038] The printing unit 4 has a plurality of inkjet heads (not shown), and performs printing by ejecting ink from the inkjet heads onto the paper P transported by the belt platen unit 33. The printing unit 4 is disposed above the belt platen unit 33.

[0039] The upper surface conveying section 5 conveys the paper P conveyed by the belt platen section 33 to the paper discharge section 6 or the inversion section 7. The upper surface conveying section 5 includes multiple pairs of upward conveying rollers 51, an upward conveying motor 52, multiple pairs of horizontal conveying rollers 53, and a horizontal conveying motor 54.

[0040] The ascending conveying rollers 51 nip the paper P conveyed by the belt platen unit 33 and convey the paper P to the upper horizontal conveying rollers 53. The ascending conveying rollers 51 are disposed along the ascending portion of the middle stream area of ​​the normal route RC.

[0041] The lifting conveying motor 52 drives the pairs of lifting conveying rollers 51 to rotate.

[0042] The horizontal conveying rollers 53 nip the paper P conveyed by the ascending conveying rollers 51 and convey it to the paper discharge section 6 or the reversing section 7. The most downstream horizontal conveying roller 53 is disposed in the upstream part of the reversing route RR. The other horizontal conveying rollers 53 are disposed in the horizontal parts in the downstream area of ​​the normal route RC.

[0043] The horizontal conveying motor 54 drives the pairs of horizontal conveying rollers 53 to rotate.

[0044] The paper discharge unit 6 discharges the printed paper P. The paper discharge unit 6 includes a switching unit 61, a pair of paper discharge rollers 62, and a paper discharge motor 63.

[0045] The switching unit 61 switches the transport path of the paper P between a paper discharge path RD that runs from the downstream end of the normal path RC toward a paper discharge tray (not shown) and a reverse path RR. The switching unit 61 is disposed at the branch point of the paper discharge path RD and the reverse path RR.

[0046] The paper discharge rollers 62 nip and transport the paper P guided to the paper discharge path RD by the switching unit 61, and discharge the paper P onto the paper discharge tray. The paper discharge rollers 62 are disposed along the paper discharge path RD.

[0047] The paper discharge motor 63 drives the paper discharge rollers 62 to rotate.

[0048] During double-sided printing, the reversing unit 7 reverses the paper P that has been printed on one side and transports it to the print transport unit 3. The reversing unit 7 includes a pair of reversing rollers 71, a reversing motor 72, a pair of re-feed rollers 73, a re-feed motor 74, and a switching gate 75.

[0049] The reversing rollers 71 nip the paper P conveyed by the horizontal conveying rollers 53 of the upper conveying section 5, and switch back to convey the paper P to the re-feed rollers 73. The reversing rollers 71 are configured to be capable of rotating forward and backward in order to perform the switchback conveyance of the paper P.

[0050] The reversing motor 72 drives the reversing roller 71 to rotate.

[0051] The sheet re-feed rollers 73 nip the sheet P that has been switched back and inverted by the reversing rollers 71, and transport it to the registration rollers 31. The sheet re-feed rollers 73 are disposed on the reversing path RR between the reversing rollers 71 and the registration rollers 31.

[0052] The re-feed motor 74 drives the re-feed roller 73 to rotate.

[0053] The switching gate 75 guides the paper P conveyed by the horizontal conveyance rollers 53 to the inversion rollers 71. The switching gate 75 also guides the paper P switched back by the inversion rollers 71 to the re-feed rollers 73.

[0054] The operation panel 8 displays various input screens and the like and accepts input operations by a user. The operation panel 8 includes a display unit (not shown) having a liquid crystal display panel or the like, and an input unit (not shown) having various operation keys, a touch panel, and the like.

[0055] The jam clearing door 9 is a door through which the user can access the internal paper feed path RS2. The jam clearing door 9 is provided on the housing of the printing device 1. The jam clearing door 9 is opened and closed by a user's operation.

[0056] The control unit 10 controls the operation of each part of the printing device 1. The control unit 10 includes a CPU, a RAM, a ROM, a hard disk, and the like.

[0057] Specifically, the control unit 10 controls the paper P to be fed from the paper feed unit 2 to the print transport unit 3, and the printing unit 4 to print on the paper P while the print transport unit 3 transports the paper P.

[0058] The control unit 10 also executes a paper dust blowing operation to blow away paper dust adhering to the paper sensor 26. Specifically, the control unit 10 controls the vertical transport rollers 23 and the registration rollers 31 to generate and release slack in the paper P between the vertical transport rollers 23 and the registration rollers 31 while the registration rollers 31 are holding the paper P, thereby generating an airflow that is blown toward the paper sensor 26.

[0059] The control unit 10 also executes a paper dust blowing operation to blow away paper dust adhering to the paper sensor 37. Specifically, while the paper P is held by the belt platen unit 33 and the pressure roller 35, the control unit 10 controls the registration roller 31 and the belt platen unit 33 to form and release slack in the paper P between the registration roller 31 and the belt platen unit 33, thereby generating an airflow that is blown toward the paper sensor 37.

[0060] Next, the operation of the printer 1 during printing will be described.

[0061] The control unit 10 controls the paper feed unit 2 to sequentially take out unprinted paper P from the external paper feed tray or the internal paper feed tray and feed it to the print transport unit 3.

[0062] The fed paper P is sent to the belt platen unit 33 by the registration rollers 31, and while being transported by the belt platen unit 33, is printed with ink ejected from the inkjet head of the printing unit 4.

[0063] In the case of single-sided printing, the printed paper P is transported from the belt platen unit 33 along the normal path RC to the upper surface transport unit 5, where it is transported by the upward transport rollers 51 and the horizontal transport rollers 53. The paper P is then guided from the normal path RC to the paper discharge path RD by the switching unit 61, and is discharged by the paper discharge rollers 62 onto the paper discharge tray.

[0064] In the case of double-sided printing, the paper P after single-sided printing is transported from the belt platen section 33 to the upper transport section 5, and then transported by the upward transport rollers 51 and horizontal transport rollers 53 in the upper transport section 5, and is guided to the inversion route RR by the switching section 61.

[0065] The paper P guided to the reversing path RR is guided by a switching gate 75 to reversing rollers 71 in the reversing unit 7, and is switched back by the reversing rollers 71. The paper P is then guided by the switching gate 75 to re-feed rollers 73, and is refed by the re-feed rollers 73 to the printing transport unit 3. The refed paper P is transported to the belt platen unit 33 by the registration rollers 31 in the printing transport unit 3.

[0066] After single-sided printing, the paper P is inverted by the inversion unit 7 and sent to the belt platen unit 33 with the unprinted side facing up. Then, while the paper P is transported by the belt platen unit 33, the unprinted side is printed by the printing unit 4. The paper P that has been printed on both sides is guided from the normal path RC to the paper discharge path RD by the switching unit 61, as in the case of single-sided printing described above, and is discharged to the paper discharge tray by the paper discharge rollers 62.

[0067] During the printing operation as described above, the control unit 10 judges whether or not a jam of the paper P has occurred based on the timing of detection of the paper P by the paper sensors 26, 37 and other paper sensors (not shown). If the control unit 10 judges that a jam of the paper P has occurred, it stops the transport of the paper P and causes the display unit of the operation panel 8 to display a screen notifying the user of the occurrence of the jam.

[0068] Next, the paper dust blowing operation in the printing device 1 will be described.

[0069] Paper dust generated by the transport of paper P in the above-mentioned printing operation adheres to and accumulates on the light-emitting portion 26a of the paper sensor 26, which may result in erroneous detection of the paper P by the paper sensor 26. In order to reduce such erroneous detection, a paper dust blowing operation is performed to blow away the paper dust adhering to the paper sensor 26. The same applies to the paper sensor 37.

[0070] First, the paper dust blowing operation targeting the paper sensor 26 will be described.

[0071] When the amount of light received by the light receiving unit 26b falls below a predetermined threshold value while the paper sensor 26 is not detecting paper P (there is no paper P between the light emitting unit 26a and the light receiving unit 26b), the control unit 10 executes a paper dust blowing operation targeting the paper sensor 26.

[0072] When performing a paper dust blowing operation targeting the paper sensor 26, the control unit 10 first controls the internal paper feed rollers 22 to take out the paper P from the internal paper feed tray, and the vertical transport rollers 23 to transport the paper P toward the registration rollers 31. The control unit 10 also drives the registration rollers 31 to rotate in the normal direction. Then, as shown in FIG. 3, the control unit 10 stops the registration rollers 31 in a state where the registration rollers 31 nip and hold the leading edge (downstream edge) of the paper P. Here, the control unit 10 controls the timing to stop the registration rollers 31 based on the timing of detection of the leading edge of the paper P by a paper sensor (not shown) arranged near the upstream side of the vertical transport rollers 23.

[0073] The control unit 10 continues to drive the vertical conveying rollers 23 in the forward direction even after the registration rollers 31 are stopped, thereby forming an upwardly convex slack in the paper P above the light emitting unit 26a, as shown in Fig. 4. When a predetermined amount of slack is formed in the paper P, the control unit 10 stops the vertical conveying rollers 23. Here, the control unit 10 controls the timing of stopping the vertical conveying rollers 23 based on the elapsed time since the registration rollers 31 were stopped.

[0074] Next, the control unit 10 drives the vertical transport rollers 23 in the reverse direction at a predetermined speed for a predetermined time. As a result, as shown in FIG. 5, the vertical transport rollers 23 transport the paper P at a predetermined speed in the opposite direction to the direction of feeding, and the slack in the paper P is removed. This generates an airflow F that flows from the portion of the paper P where the slack was formed toward the light-emitting unit 26a. This airflow F is blown toward the light-emitting unit 26a, so that at least a portion of the numerous pieces of paper dust 81 adhering to the light-emitting unit 26a are blown away and fall. This reduces or removes the paper dust 81 adhering to the paper sensor 26.

[0075] Next, while keeping the registration roller 31 nipped with the paper P, the control unit 10 drives the vertical conveying roller 23 in the forward direction as described above to create slack in the paper P, and then drives the vertical conveying roller 23 in the reverse direction to remove the slack in the paper P.

[0076] The control unit 10 controls the vertical transport rollers 23 to repeat the paper dust blowing operation for forming a slack in the paper P as described above and then removing the slack a predetermined number of times.

[0077] Here, because the paper sensor 26 is disposed at a position where the internal paper feed path RS2 is curved, the distance between the light-emitting unit 26a and the internal paper feed path RS2 is relatively large. Therefore, the paper dust accumulated on the light-emitting unit 26a is difficult to blow away by the transport airflow generated by the paper transport. In contrast, the paper dust blowing operation described above can blow away the paper dust accumulated on the light-emitting unit 26a.

[0078] When the paper dust blowing operation is completed a predetermined number of times, the control unit 10 causes the display unit of the operation panel 8 to display a selection screen that allows the user to select whether to use the paper P used in the paper dust blowing operation for printing or to discard it.

[0079] When the paper P used for the paper dust blowing operation is selected to be used for printing, the control unit 10 transports the paper P from the registration rollers 31 to the belt platen unit 33, and controls the printing unit 4 to print on the paper P while the paper P is being transported by the belt platen unit 33.

[0080] When it is selected to discard the paper P used in the paper dust blowing operation, the control unit 10 controls the vertical transport rollers 23 to transport the paper P from the jam release door 9 to a predetermined position accessible to the user.

[0081] When the paper P reaches a predetermined position, the user opens the jam release door 9 and removes the paper P. This allows the user to remove the paper P easily.

[0082] In addition, in the case of a paper dust blowing operation targeting the paper sensor 26, the vertical transport rollers 23 correspond to a first transport section, and the registration rollers 31 correspond to a second transport section.

[0083] Next, the paper dust blowing operation targeting the paper sensor 37 will be described.

[0084] Similar to the paper dust blowing operation targeting the paper sensor 26 described above, the control unit 10 executes a paper dust blowing operation targeting the paper sensor 37 when the amount of light received by the light receiving unit 37b falls below a predetermined threshold value when the paper sensor 37 is not detecting paper P (there is no paper P between the light emitting unit 37a and the light receiving unit 37b).

[0085] When performing the paper dust blowing operation targeting the paper sensor 37, the control unit 10 first controls the internal paper feed rollers 22 to take out the paper P from the internal paper feed tray, and the vertical conveying rollers 23 and the registration rollers 31 to convey the paper P toward the belt platen unit 33. The control unit 10 also drives the belt platen unit 33. Then, as shown in FIG. 6, the control unit 10 stops the belt platen unit 33 in a state in which the leading edge (downstream end) of the paper P is held by the driven roller 43 and the pressure roller 35 of the belt platen unit 33 nipping the leading edge (downstream end) of the paper P together with the conveying belt 41. Here, the control unit 10 controls the timing to stop the belt platen unit 33 based on the timing of detection of the leading edge of the paper P by a paper sensor (not shown) arranged near the upstream side of the vertical conveying rollers 23.

[0086] The control unit 10 continues to drive the registration rollers 31 in the forward direction even after the belt platen unit 33 has stopped, thereby forming an upwardly convex slack in the paper P above the light emitting unit 37a, as shown in Fig. 7. When a predetermined amount of slack is formed in the paper P, the control unit 10 stops the registration rollers 31. Here, the control unit 10 controls the timing at which the registration rollers 31 are stopped based on the elapsed time since the belt platen unit 33 was stopped.

[0087] Next, the control unit 10 drives the registration rollers 31 in the reverse direction at a predetermined speed for a predetermined time. As a result, as shown in FIG. 8, the registration rollers 31 transport the paper P at a predetermined speed in the opposite direction to the direction of feeding, and the slack in the paper P is removed. This generates an airflow F that flows from the portion of the paper P where the slack was formed toward the light-emitting unit 37a. This airflow F is blown toward the light-emitting unit 37a, and at least some of the numerous pieces of paper dust 81 that have adhered to the light-emitting unit 37a are blown away and fall. This reduces or removes the paper dust 81 that has adhered to the paper sensor 37.

[0088] Next, while maintaining the state in which the belt platen portion 33 and the pressure roller 35 hold the paper P, the control unit 10 drives the registration roller 31 in the forward direction as described above to create slack in the paper P, and then drives the registration roller 31 in the reverse direction to remove the slack in the paper P.

[0089] The control unit 10 controls the registration rollers 31 to repeat the paper dust blowing operation for removing the slack after forming the slack in the paper P as described above a predetermined number of times.

[0090] When a predetermined number of paper dust blowing operations have been completed, the control unit 10 causes the display unit of the operation panel 8 to display a selection screen that allows the user to select whether to use the paper P used in the paper dust blowing operation for printing or to discard it, as in the case of the paper dust blowing operation targeting the paper sensor 26.

[0091] When it is selected that the paper P used in the paper dust blowing operation is to be used for printing, the control unit 10 controls the printing unit 4 to print on the paper P while the belt platen unit 33 transports the paper P.

[0092] When it is selected to discard the paper P used in the paper dust blowing operation, the control unit 10 controls the registration rollers 31 and the vertical transport rollers 23 to transport the paper P to a predetermined position.

[0093] When the paper P reaches a predetermined position, the user opens the jam release door 9 and removes the paper P. This allows the user to remove the paper P easily.

[0094] In addition, in the case of a paper dust blowing operation targeting the paper sensor 37, the registration rollers 31 correspond to a first conveying section, and the belt platen section 33 and the pressure roller 35 constitute a second conveying section.

[0095] As described above, in the printing device 1, during the paper dust blowing operation targeting the paper sensor 26, the control unit 10 controls the vertical conveying roller 23 and the registration roller 31 to create and release slack in the paper P between the vertical conveying roller 23 and the registration roller 31 while the registration roller 31 holds the paper P, thereby generating an airflow that is blown toward the paper sensor 26.

[0096] In addition, in the paper dust blowing operation targeting the paper sensor 37, the control unit 10 controls the registration roller 31 and the belt platen unit 33 to generate and release slack in the paper P between the registration roller 31 and the belt platen unit 33 while the paper P is held by the belt platen unit 33 and the pressure roller 35, thereby generating an airflow to be blown toward the paper sensor 37.

[0097] In this way, the printing device 1 uses paper P to blow air onto the paper sensors 26, 37 to blow away paper dust, thereby reducing or removing paper dust adhering to the paper sensors 26, 37 without providing any additional mechanisms or components.

[0098] Furthermore, the paper dust blowing operation can reduce or remove dust adhering to the paper sensors 26, 37, so that the frequency of cleaning the paper sensors 26, 37 can be reduced.

[0099] In the printing device 1, in a paper dust blowing operation aimed at the paper sensor 26, the vertical transport rollers 23 are driven in forward and reverse directions while the registration rollers 31 are holding the paper P, thereby creating and releasing slack in the paper P, and generating an airflow to be blown toward the paper sensor 26. In a paper dust blowing operation aimed at the paper sensor 37, the registration rollers 31 are driven in forward and reverse directions while the belt platen section 33 and the pressure roller 35 are holding the paper P, thereby creating and releasing slack in the paper P, and generating an airflow to be blown toward the paper sensor 37. This makes it possible to perform the paper dust blowing operation multiple times with just one sheet of paper P.

[0100] Furthermore, since the formation and release of slack in the paper P is repeated multiple times, the effect of reducing or removing dust adhering to the paper sensors 26, 37 can be enhanced.

[0101] In the above embodiment, the formation and removal of the slack in the sheet P is repeated multiple times, but it may be performed only once.

[0102] The present invention is not limited to the above-described embodiment, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment.

[0103] [Note] This application discloses the following inventions.

[0104] (Appendix 1) a first conveying unit that conveys paper; a second transport section disposed downstream of the first transport section in a paper transport direction and configured to transport the paper; a detection unit disposed between the first transport unit and the second transport unit and configured to detect a sheet; a control unit that controls the first transport unit and the second transport unit to form and release slack in the paper between the first transport unit and the second transport unit while the second transport unit is holding the paper, thereby generating an airflow to be blown to the detection unit; A conveying device comprising: [Explanation of symbols]

[0105] 1 Printing device 2 Paper feed section 3 Printing transport section 4 Printing Department 5 Upper conveyor section 6 Paper output section 7 Reversal section 8 Operation Panel 9 Jam release door 10 Control section 23 Vertical conveying roller 31 Registration roller 35,36 Presser roller 26,37 Paper sensor 26a, 37a Light emitting part 26b,37b Light receiving part

Claims

[Claim 1] A first conveying unit that conveys paper; a second transport section disposed downstream of the first transport section in a paper transport direction and configured to transport the paper; a detection unit disposed between the first transport unit and the second transport unit and configured to detect a sheet; a control unit that controls the first transport unit and the second transport unit to form and release slack in the paper between the first transport unit and the second transport unit while the second transport unit holds the paper, thereby generating an airflow to be blown to the detection unit; A conveying device comprising:

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