Sheet conveying device and image forming apparatus

Abstract

To prevent a sheet from rebounding with a simple and inexpensive structure.SOLUTION: The sheet conveying device 2 includes a sheet conveying passage 30, a conveying roller 32 that conveys a sheet P along the sheet conveying passage 30, an aligning plate 40 that is provided on one end side of the sheet conveying passage 30 in a sheet width direction Y so as to be parallel to a sheet conveying direction X and aligns a position of the sheet P in the sheet width direction Y, an aligning roller 50 that rotates in the sheet width direction Y while being in contact with the sheet P on the sheet conveying passage 30 and abuts the sheet P against the aligning plate 40, and a sheet pressing mechanism 60 that contacts the sheet on the sheet conveying passage 30 from above and suppresses movement of the sheet P in a direction away from the aligning plate 40.SELECTED DRAWING: Figure 8C

Description

[Technical Field]

[0001] The present invention relates to a paper transport device and an image forming device, and more particularly to a technique for aligning the position of a paper sheet in the width direction. [Background technology]

[0002] In a typical paper transport device, a technique is known in which an alignment roller abuts one widthwise edge of the paper against an alignment plate that is arranged parallel to the paper transport direction, thereby aligning the paper widthwise. However, this technique has the problem that the impact from the alignment plate when the paper abuts against the alignment plate causes the paper to bounce back.

[0003] To solve this problem, for example, Patent Document 1 discloses a technology that prevents the paper from bouncing off the stopper by controlling the rotation of the motor and slowing down the paper transport speed at a constant acceleration before the paper hits the stopper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2011 / 086700 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the technology disclosed in Patent Document 1, the load on the motor increases as the paper conveyance speed increases due to deceleration, and therefore an expensive, high-performance motor is required.

[0006] The present invention has been made in view of the above circumstances, and has as its object to prevent paper from bouncing back with a simple and inexpensive configuration. [Means for solving the problem]

[0007] A paper transport device according to one aspect of the present invention comprises a paper transport path, a transport roller that transports paper along the paper transport path, an alignment plate that is arranged parallel to the paper transport direction at one end of the paper transport path in a direction perpendicular to the paper transport direction and that aligns the position of the paper in the perpendicular direction, an alignment roller that rotates in the perpendicular direction while in contact with the paper on the paper transport path and presses the paper against the alignment plate, and a paper pressing mechanism that contacts the paper on the paper transport path from above and suppresses movement of the paper in a direction away from the alignment plate.

[0008] An image forming apparatus according to another aspect of the present invention includes the above-described paper transport device and an image forming section that forms an image on the paper transported by the transport roller. [Effects of the Invention]

[0009] According to the present invention, the paper pressing mechanism has a simple and inexpensive configuration, and can prevent the paper from bouncing back without using an expensive and high-performance motor. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a front cross-sectional view showing the structure of the image forming apparatus. [Figure 2] 1 is a block diagram showing a configuration of an image forming apparatus 1. FIG. [Figure 3] FIG. 2 is a perspective view showing a part of a paper transport path. [Figure 4] FIG. 4 is a perspective view showing a state in which a sheet passes through a part of the sheet transport path. [Figure 5] FIG. 4 is a side view showing the paper pressing mechanism. [Figure 6] FIG. 2 is a perspective view showing a paper pressing mechanism. [Figure 7] 10 is a flowchart showing a sheet alignment process. [Figure 8A] 10A and 10B are diagrams illustrating a state in which the paper pressing mechanism takes a retracted position. [Figure 8B] 10A and 10B are diagrams illustrating a state in which the paper pressing mechanism assumes a pressing position. [Figure 8C] FIG. 10 is a diagram showing a state when sheets are aligned. DETAILED DESCRIPTION OF THE INVENTION

[0011] An image forming apparatus including a paper transport device according to an embodiment of the present invention will be described below with reference to the drawings.

[0012] [Configuration of image forming apparatus 1] 1 is a front cross-sectional view showing the structure of image forming apparatus 1. Referring to FIG. 1, image forming apparatus 1 is a multifunction device equipped with multiple functions such as a copy function, a transmission function, a printer function, and a facsimile function. Image forming apparatus 1 includes an image reading unit 11, an image forming unit 12, a paper feed unit 13, a paper transport path 30, transport rollers 32, and an ejection roller 33.

[0013] Image reading unit 11 reads an original document by a moving original document method or a fixed original document method to generate image data. Specifically, image reading unit 11 is an ADF (Auto Document Feeder) that includes an original document transport unit 6 that transports an original document placed on an original document table, and a scanner that optically reads an original document transported by original document transport unit 6 or an original document placed on platen glass 7.

[0014] Image forming unit 12 uses an inkjet system to form an image represented by image data on paper P transported through paper transport path 30. Paper feed unit 13 uses a pickup roller to pull out paper P stored in a paper feed cassette and feeds it to paper transport path 30. Note that paper P is not limited to paper media and may be, for example, an overhead projector (OHP) sheet.

[0015] The transport rollers 32 transport the paper P along the paper transport path 30. The discharge rollers 33 discharge the paper P on which the image has been formed onto the discharge tray 8. The transport rollers 32 and the discharge rollers 33 are connected to a first drive motor provided in the drive unit 14, which will be described later.

[0016] Fig. 2 is a block diagram showing the configuration of the image forming apparatus 1. Referring to Fig. 2, the image forming apparatus 1 includes a control unit 100. The control unit 100 includes a processor, a RAM (Random Access Memory), and a ROM (Read Only Memory). The processor is, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or an ASIC (Application Specific Integrated Circuit).

[0017] The control unit 100 functions as the control unit 10 when various computer programs stored in the built-in ROM or HDD (Hard Disk Drive) 18 are executed by the above-mentioned processor. Note that the control unit 10 may be configured to be operable by a logic circuit without relying on operations based on computer programs, or may be configured to be realized by two or more control units.

[0018] The control unit 100 is electrically connected to the document transport unit 6, image reading unit 11, image forming unit 12, paper feeding unit 13, drive unit 14, display unit 15, operation unit 16, HDD 18, image processing unit 19, image memory 20, facsimile communication unit 21, and communication unit 22, etc.

[0019] The drive unit 14 includes a first drive motor for rotating the conveying roller 32 and the discharge roller 33, a second drive motor for rotating the alignment roller 50 described later, and a third drive motor for rotating the paper pressing mechanism 60 described later.

[0020] The display unit 15 is a display device including a liquid crystal display or an organic light-emitting diode (EL) display, and displays various screens.

[0021] The operation unit 16 includes a plurality of hard keys including a start key 16A. The operation unit 16 also includes a touch panel 16B that is placed over the display unit 15. The operation unit 16 receives instructions from the user.

[0022] The HDD 18 stores image data generated by the image reading unit 11, and various computer programs for realizing the operations of the image forming apparatus 1. The HDD 18 stores, as part of the various computer programs, a control program for executing a sheet alignment process, which will be described later.

[0023] The image processing unit 19 performs image processing as necessary on the image data generated by the image reading unit 11. The image memory 20 temporarily stores the image data generated by the image reading unit 11. The facsimile communication unit 21 transmits and receives the image data via a public line.

[0024] The communication unit 22 includes a communication module such as a LAN (Local Area Network) board. The control unit 10 performs data communication via the communication unit 22 with an external device such as a PC (Personal Computer) 23 connected via a network.

[0025] A power supply is connected to each part of the image forming apparatus 1. When the power supply is turned on by a user, power is supplied to each part of the image forming apparatus 1 from the power supply.

[0026] Hereinafter, the paper transport path 30, transport rollers 32, alignment plate 40, alignment rollers 50, paper pressure rollers 70, and the like that constitute the paper transport device 2 according to this embodiment will be described with reference to FIGS.

[0027] As shown in Fig. 3, a transport roller 32 is provided on the paper transport path 30. The transport roller 32 is attached to the longitudinal center of a rotation shaft 34 that extends in a direction Y (hereinafter referred to as the "paper width direction") perpendicular to the paper transport direction X. The rotation shaft 34 is connected to a drive shaft 36 via a gear train that meshes with each other. The drive shaft 36 is connected to a first drive motor.

[0028] When the first drive motor is driven to rotate the drive shaft 36, the drive force is transmitted to the rotary shaft 34 via a gear train, causing the rotary shaft 34 to rotate. As the rotary shaft 34 rotates, the transport roller 32 rotates clockwise on the page while in contact with the top surface of the paper P, and the paper P is transported along the paper transport path 30, as shown in FIG.

[0029] A paper pressure mechanism 60 is provided at one end of the paper transport path 30 in the paper width direction Y, upstream of the transport roller 32 in the paper transport direction X. As shown in FIG. 5, an alignment plate 40 is provided below the paper pressure mechanism 60. The alignment plate 40 is positioned so that one side of the alignment plate 40 on the transport roller 32 side is parallel to the paper transport direction X. Alignment plate 40 aligns the position of the paper P in the paper width direction Y by the one side surface.

[0030] 6, the paper pressure mechanism 60 includes a frame member 62 having a substantially U-shaped cross section in the longitudinal direction, the frame member 62 including a pair of opposing side portions 62A, 62B and a connecting portion 62C connecting the side portions 62A, 62B. An alignment roller 50 is provided between the side portions 62A, 62B so as to protrude in the opening direction of the substantially U-shaped frame member 62.

[0031] The alignment roller 50 is rotatably supported by a rotation shaft 52 that penetrates the side surface portions 62A and 62B. The rotation shaft 52 extends in the paper transport direction X and is connected to a second drive motor. When the second drive motor rotates the rotary shaft 52, the alignment roller 50 rotates. The alignment roller 50 rotates clockwise in the plane of the drawing while in contact with the sheet P on the sheet transport path 30, moving the sheet P in the sheet width direction Y toward the alignment plate 40 (hereinafter referred to as the "sheet alignment direction Y1") until the sheet P abuts against the alignment plate 40.

[0032] A paper pressure roller 70 is attached to the side surface portion 62A via a support member 72. The support member 72 is fixed to the side surface portion 62A with screws. The paper pressure roller 70 is attached to the support member 72 so as to protrude in the opening direction of the approximately U-shaped frame member 62. In this way, the paper pressure roller 70 is provided near the alignment roller 50.

[0033] The paper pressure roller 70 is composed of a cylindrical one-way clutch 70A and an elastic body 70B that covers the circumferential surface of the one-way clutch 70A. The one-way clutch 70A rotates only clockwise on the paper surface, and does not rotate counterclockwise on the paper surface. The material of the elastic body 70B is not particularly limited, but may be, for example, rubber or sponge.

[0034] When the paper pressure roller 70 is in contact with the paper P on the paper transport path 30 from above, it rotates along with the paper P when the paper P moves in the paper alignment direction Y1, but does not rotate when the paper P moves in a direction away from the alignment plate 40 (hereinafter referred to as the "paper bounce direction Y2"). In this way, the paper pressure roller 70 contacts the paper P on the paper transport path 30 from above and suppresses the movement of the paper P in the paper bounce direction Y2.

[0035] One longitudinal end of the side surface portions 62A, 62B is rotatably supported by a rotation shaft 62D (shown in Figure 5) that penetrates the side surface portions 62A, 62B. The rotation shaft 62D extends in the paper transport direction X and is connected to a third drive motor. When the rotation shaft 62D is rotated by the drive of the third drive motor, the frame member 62 rotates around the rotation shaft 62D.

[0036] By rotating the frame member 62, the paper pressing mechanism 60 takes on a pressing position in which the alignment roller 50 and the paper pressing roller 70 contact the top surface of the paper P on the paper transport path 30, and a retracted position in which the alignment roller 50 and the paper pressing roller 70 do not contact the top surface of the paper P on the paper transport path 30.

[0037] A paper detection sensor is provided near the paper pressing mechanism 60 on the paper transport path 30. The paper detection sensor is a photosensor that detects the presence or absence of paper P being transported on the paper transport path 30, and includes a light emitting element and a light receiving element that are arranged opposite each other so that paper P passes between them.

[0038] The paper detection sensor outputs an OFF signal when it detects paper P, and outputs an ON signal when it does not detect paper P. Note that the paper detection sensor is not limited to a photosensor, and may be, for example, a mechanical sensor configured to physically detect contact with paper P.

[0039] [Operation] 7 to 8C, the operation of the image forming apparatus 1 when performing the sheet alignment process will be described below. In the following description, the control unit 10 of the image forming apparatus 1 functions as a part of the sheet transport device 2.

[0040] It is assumed that the user places a document on the platen glass 7 and presses the start key 16A to input an instruction to execute a copy process. When the control unit 10 detects that the start key 16A has been pressed, it causes the image reading unit 11 to read the document on the platen glass 7 and generate image data.

[0041] The control unit 10 causes the paper feed unit 13 to feed the paper P stored in the paper feed cassette to the paper transport path 30. The control unit 10 also drives the first drive motor to rotate the transport roller 32, thereby transporting the paper P along the paper transport path 30.

[0042] When the control unit 10 starts rotating the transport rollers 32, it starts executing the paper alignment process shown in Fig. 7. As shown in Fig. 8A, at the start of the paper alignment process, the paper pressure mechanism 60 is in the retracted position, which is its home position. At this time, the alignment rollers 50 and the paper pressure rollers 70 are above the paper transport path 30 and are in positions where they do not come into contact with the paper P on the paper transport path 30.

[0043] When the paper alignment process starts, the control unit 10 repeats the process of determining that the paper P on the paper transport path 30 has not been detected until the paper detection sensor outputs an OFF signal (NO in step S10). In this situation, when the leading edge of the paper P transported by the transport rollers 32 reaches the position of the paper detection sensor, the output signal of the paper detection sensor switches from an ON signal to an OFF signal.

[0044] When the control unit 10 detects that the paper detection sensor has output an OFF signal, it determines that paper P has been detected (YES in step S10), and stops driving the first drive motor to stop the rotation of the transport roller 32 (step S11).

[0045] After processing step S11, control unit 10 drives third drive motor to rotate rotation shaft 62D clockwise on the paper surface, thereby rotating paper pressure mechanism 60 downward, thereby changing the posture of paper pressure mechanism 60 from the retracted posture shown in Fig. 8A to the pressing posture shown in Fig. 8B (step S12). As a result, alignment roller 50 and paper pressure roller 70 descend and come into contact with paper P on paper transport path 30.

[0046] After processing step S12, the control unit 10 drives the second drive motor to rotate the alignment roller 50 clockwise on the paper surface a predetermined number of rotations while in contact with the paper sheet P (step S13). As a result, the paper sheet P moves in the paper alignment direction Y1, and as shown in Fig. 8C, one end of the paper sheet P in the paper width direction Y abuts against the alignment plate 40. At this time, the paper sheet pressure roller 70 rotates idly as the paper sheet P moves in the paper alignment direction Y1.

[0047] Here, when the sheet P hits the alignment plate 40, a force is applied to the sheet P to bounce in the sheet bounce direction Y2. However, the sheet pressure roller 70 does not rotate in response to the movement of the sheet P in the sheet bounce direction Y2, and therefore the sheet pressure roller 70 prevents the sheet P from moving in the bounce direction Y2.

[0048] After processing step S13, the control unit 10 drives the third drive motor to rotate the rotation shaft 62D counterclockwise on the paper surface, thereby rotating the paper pressing mechanism 60 upward, thereby returning the position of the paper pressing mechanism 60 from the pressing position shown in Figure 8B to the retracted position shown in Figure 8A (step S14).

[0049] After processing step S14, the control unit 10 resumes driving the first drive motor to start rotating the transport roller 32 (step S15). After processing step S15, the control unit 10 ends the paper alignment process. The control unit 10 causes the image forming unit 12 to form an image on the paper P transported along the paper transport path 30, and causes the discharge roller 33 to discharge the paper P with the image formed onto the discharge tray 8.

[0050] According to the above embodiment, the paper transport device 2 can prevent the paper P from bouncing off the alignment plate 40 by using the simple and inexpensive configuration of the paper pressure mechanism 60, without using an expensive and high-performance motor. As a result, the position of the paper P in the paper width direction Y is accurately aligned, and the skew of the paper P is reliably corrected.

[0051] Furthermore, according to the above embodiment, the paper pressure roller 70 rotates in response to the movement of the paper P in the paper alignment direction Y1, but does not rotate in response to the movement of the paper P in the paper rebound direction Y2. This allows the paper P to abut against the alignment plate 40 without applying a load to the alignment roller 50, and also reliably prevents the paper P from bouncing back due to the abutment.

[0052] Furthermore, according to the above embodiment, the paper pressure roller 70 is composed of a cylindrical one-way clutch 62A and an elastic body 62B that covers the circumferential surface of the one-way clutch 62A. This makes it possible to prevent the paper P from bouncing back with an even simpler and less expensive configuration.

[0053] Furthermore, according to the above embodiment, the paper pressure roller 70 is provided near the alignment roller 50. This makes it possible to more efficiently prevent the paper P from bouncing back.

[0054] Furthermore, according to the above embodiment, the image forming apparatus 1 includes the paper transport device 2, so that the image forming section 12 can form an image on the paper P at an accurate position.

[0055] (Variation) In the above embodiment, the paper transport device 2 is provided inside the image forming apparatus 1, but the present invention is not limited to such an embodiment. For example, the paper transport device 2 may be provided inside the document transport unit 6 of the image reading unit 11 in order to correct misalignment of the optical axis of the paper P. Furthermore, the paper transport device 2 may be provided inside a post-processing device that performs post-processing such as stapling or punching on the paper P transported from the image forming apparatus 1.

[0056] In the above embodiment, the inkjet image forming apparatus 1 has been described as an example, but the present invention is not limited to such an embodiment. The image forming apparatus 1 may be, for example, an electrophotographic image forming apparatus.

[0057] The configuration and processing of the embodiment described above using FIGS. 1 to 8C are merely one embodiment of the present invention, and the present invention is not limited to these configurations and processing. [Explanation of symbols]

[0058] 2 Paper transport device 30 Paper transport path 32 Transport roller 40 Matching plate 50 Alignment roller 60 Paper holding mechanism 70 Paper pressure roller 70A One-way Clutch 70B Elastic body

Claims

1. a paper transport path; a transport roller that transports the paper along the paper transport path; an alignment plate provided at one end of the paper transport path in a direction perpendicular to the paper transport direction so as to be parallel to the paper transport direction, and aligning the position of the paper in the perpendicular direction; an alignment roller that rotates in the perpendicular direction while in contact with the paper on the paper transport path to abut the paper against the alignment plate; a paper pressing mechanism that contacts the paper on the paper transport path from above and suppresses movement of the paper in a direction away from the alignment plate.

2. 2. The paper transport device according to claim 1, wherein the paper pressing mechanism includes a paper pressing roller that rotates in response to movement of the paper toward the alignment plate and does not rotate in response to movement of the paper away from the alignment plate.

3. 3. The paper transport device according to claim 2, wherein the paper pressure roller comprises a cylindrical one-way clutch and an elastic body covering the peripheral surface of the one-way clutch.

4. 3. The paper transport device according to claim 2, wherein the paper pressure roller is provided near the alignment roller.

5. The paper transport device according to claim 1 ; an image forming unit that forms an image on the paper transported by the transport roller.

Images