Recording device

Abstract

To provide a technology that can prevent reverse rotation of a conveyance roller with a simple configuration without increasing a drive load when the conveyance roller rotates in a normal rotation direction.SOLUTION: A recording device includes: a first roller 28 that rotates in a normal rotation direction and conveys a sheet in a conveyance direction; a first gear that transmits drive to the first roller 28; a second gear that engages with the first gear; an idling part in which the second gear can idly rotate; and a locking part that locks the second gear so as to restrict rotation of the second gear when the first gear receives a force that rotates the first roller in a second direction opposite to a first direction in which the first roller rotates in the normal rotation direction.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image recording apparatus, and more particularly to an image recording apparatus having a mechanism for restricting a transport roller from rotating in a direction opposite to a sheet transport direction. [Background technology]

[0002] Conventionally, there is known a paper image recording device that corrects skew by bending the sheet between two rollers or abutting the edge of the sheet against one of the rollers when conveying the sheet. In this case, the roller upstream in the conveying direction receives a reaction force from the sheet, and a return force is generated that tries to rotate the roller in the opposite direction to the conveying direction. If the roller rotates in the opposite direction to the conveying direction due to the return force, the bending of the sheet is eliminated or the abutment state of the edge of the sheet is released, and there is a risk that the skew of the sheet is not sufficiently corrected. Therefore, as shown in Patent Document 1 and Patent Document 2, a mechanism for suppressing the reverse rotation of the roller is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-035688 A [Patent Document 2] Japanese Patent Application Publication No. 06-016261 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 and Patent Document 2 use biasing members such as springs and resisting members such as viscous grease. Therefore, when the transport roller rotates to transport paper, it rotates while receiving the force of the biasing members and resisting members, so the drive load when the transport roller rotates is high, and there are problems such as an increase in the size of the drive motor, an increase in the number of parts, and an increase in power consumption. In addition, there is a problem of an increase in the size of the device because space is required to arrange the springs, etc.

[0005] An object of the present invention is to provide a technique capable of preventing the reverse rotation of the transport rollers with a simple configuration without increasing the drive load during forward rotation of the transport rollers. [Means for solving the problem]

[0006] In order to achieve the above object, the recording device of the present invention comprises: a first gear that transmits driving force to the first roller; A second gear that meshes with the first gear; an idling portion in which the second gear can idly rotate; a locking portion that locks the second gear so as to restrict rotation of the second gear when the first gear receives a force that rotates the first roller in a second direction opposite to a first direction in which the first roller rotates in the forward rotation direction; The present invention is characterized by comprising: Effect of the Invention

[0007] According to the present invention, it is possible to prevent the transport roller from rotating in the reverse direction with a simple configuration without increasing the drive load during forward rotation of the transport roller. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an image recording apparatus according to an embodiment of the present invention; [Diagram 2] Block diagram of an image recording apparatus according to the present embodiment. [Diagram 3] FIG. 1 is a perspective view showing a conveying unit of an image recording apparatus according to an embodiment of the present invention; [Figure 4] FIG. 1 is a diagram showing the configuration of a one-way clutch in this embodiment; [Diagram 5] FIG. 1 is a diagram showing the configuration of a one-way clutch in this embodiment; [Figure 6] FIG. 1 is a diagram showing the direction and path of drive transmission in this embodiment. [Figure 7] FIG. 1 is a diagram showing the direction and path of drive transmission in this embodiment. [Figure 8] FIG. 4 is a diagram showing a driving configuration of a conveying unit in the present embodiment. [Figure 9] FIG. 13 is a diagram showing the driving direction and the state of the second gear in this embodiment. [Figure 10] FIG. 13 is a diagram showing the driving direction and the state of the second gear in this embodiment. [Figure 11] FIG. 13 is a diagram showing the driving direction and the state of the second gear in this embodiment. [Figure 12] FIG. 2 is a diagram showing the arrangement of a second gear in this embodiment; [Figure 13] FIG. 3 is a cross-sectional view showing a second gear receiving portion in the embodiment; [Figure 14] FIG. 13 is a diagram showing a first registration operation of the image recording device according to the embodiment. [Figure 15] FIG. 11 is a diagram showing a second registration operation of the image recording device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, with reference to the drawings, the mode for carrying out the present invention will be described in detail by way of example. The dimensions, materials, shapes, and relative positions of the components described in the embodiments should be appropriately changed depending on the configuration of the device to which the invention is applied and various conditions. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the present invention. The components described in the embodiments are merely examples, and are not intended to limit the scope of the present invention to only those.

[0010] (First embodiment) 1 is a perspective view showing the internal configuration of a recording device M according to a first embodiment of the present invention. The recording device M is a multifunction device equipped with a print unit and a scanner unit (not shown) disposed on the print unit, and various processes relating to image recording and reading operations can be performed by the print unit and the scanner unit individually or in conjunction with each other.

[0011] The scanner unit includes an ADF (automatic document feeder) and an FBS (flatbed scanner), and can read documents automatically fed by the ADF and read (scan) documents placed on the platen of the FBS by the user. Note that the recording device according to this embodiment is a multifunction device that includes both a print unit and a scanner unit, but may not include a scanner unit.

[0012] The printing unit is generally composed of a first paper feed unit 1, a second paper feed unit 2, a conveying unit 3, a recording unit 4, and a paper discharge unit 8. The first paper feed unit 1 and the second paper feed unit 2 are loaded with sheets as recording media by the user. The conveying unit 3 conveys the sheets fed from the first paper feed unit 1 or the second paper feed unit 2 on a predetermined sheet conveying path with high accuracy. The recording unit 4 records an image on the sheet being conveyed by the conveying unit 3. The recording unit 4 is, for example, a liquid ejection type recording unit that ejects ink as a recording liquid onto the sheet to record an image on the sheet. The paper discharge unit 8 is loaded with sheets that have been ejected after an image has been recorded. The paper discharge unit 8 is composed of a sheet stacking unit 81 and an extension tray 82 that can be pulled out from the recording device M to expand the stacking area when a large-sized sheet is discharged. Furthermore, it is composed of a maintenance unit 5 which performs maintenance of the recording unit 4, and a drive unit 6 which switches and transmits the drive to either the first paper feed unit 1, the second paper feed unit 2, or the maintenance unit 5 using the drive of a transport motor 31 formed in the transport unit 3. All of these units are fastened to a base 7 to form the print unit.

[0013] Next, a series of steps for recording an image on a sheet by the recording device M in this embodiment will be described. A sheet is fed to the conveying section 3 by a sheet feeding section 2 (not shown). The sheet fed from the sheet feeding section 2 is conveyed by a conveying roller 32 and a pinch roller 33 driven by the conveying roller 32. The roller pair aligns the positions of the left and right leading ends of the sheet in the width direction with respect to the conveying direction.

[0014] The recording unit 4 is composed of a carriage 41 on which a recording head 42 is mounted, and a chassis 44 that supports the carriage 41. The carriage 41 can move back and forth in a scanning direction that perpendicularly intersects with the conveying direction of the fed sheet. When the sheet conveyed by the pair of conveying rollers passes over a platen that biases the sheet and is provided at a position opposite to the recording unit 4, an image is recorded on the sheet by the recording head 42 while the carriage 41 is scanning.

[0015] Thereafter, an image is recorded on one side of the sheet, and the sheet on which the image has been recorded is discharged to the discharge section 8 through a pair of discharge rollers, a discharge roller 34 and a spur 35 .

[0016] FIG. 2 is a block diagram of the recording device M in this embodiment. 901 is an MPU that controls the operation of each unit and data processing. 902 is a ROM that stores programs and data executed by the MPU 901. 903 is a RAM that temporarily stores processing data executed by the MPU 901 and data received from a host computer 906. The recording head 42 is controlled by a recording head driver 942. The carriage 41 is driven by a carriage motor 43. The carriage motor 43 is controlled by a carriage motor driver 943. The conveying roller 32 and the paper discharge roller 34 are driven by a conveying motor 31. The conveying motor 31 is controlled by a conveying motor driver 931. The host computer 906 has a printer driver 9061 for processing recording information such as a recorded image and image quality and communicating with the recording device M when a user commands the execution of a recording operation. The MPU 901 exchanges recorded images and the like with the host computer 906 via an I / F unit 905.

[0017] FIG. 3 is a perspective view showing a conveying unit of a recording apparatus in this embodiment. A conveying motor 31 as a single driving source is connected (driving-coupled) to a conveying roller 32 by a drive train 26. The conveying roller 32 can rotate in a direction opposite to the rotation direction (hereinafter, forward rotation or forward direction) in which the sheet P is conveyed in the conveying direction according to the rotation direction of the conveying motor 31. The intermediate roller 28 is connected (driving-coupled) to the conveying roller 32 via a drive train 27. A one-way rotation mechanism, which is a combination of a one-way clutch 72 and a one-way clutch 73 and will be described later, is disposed in the middle of the drive train 27. The rotation input from the intermediate input gear 61 can be transmitted to the intermediate roller input gear 66 only in the rotation direction shown in FIG. 3, regardless of the rotation direction of the intermediate input gear 61, by passing through the one-way rotation mechanism. When the intermediate roller input gear 66 receives an input in the illustrated direction, the intermediate roller 28 rotates in the rotation direction (hereinafter, forward rotation) shown in FIG. 3 in which the sheet P is conveyed in the conveying direction.

[0018] That is, the intermediate roller 28 as the first roller and the conveying roller 32 as the second roller can be driven by the driving force of the conveying motor 31, which is a common driving source. Also, with the above configuration, by switching the rotation direction of the conveying motor 31, it is possible to switch between a state in which the conveying roller 32 rotates forward while the intermediate roller 28 rotates forward, and a state in which the conveying roller 32 rotates backward while the intermediate roller 28 rotates forward.

[0019] Figures 4(a) to 5(b) are diagrams showing the configuration of a one-way clutch used in the one-way rotation mechanism in this embodiment. Figure 4(a) is an exploded perspective view of one-way clutch 72, and Figure 4(b) is an assembled perspective view of one-way clutch 72 when each member is assembled according to the arrows in Figure 4(a). Figure 5(a) is an exploded perspective view of one-way clutch 73, and Figure 5(b) is an assembled perspective view of one-way clutch 73 when each member is assembled according to the arrows in Figure 5(a). Each clutch may have only one planetary gear, or may have three or more planetary gears.

[0020] As shown in FIG. 4(a) and FIG. 4(b), the one-way clutch 72 is composed of a first input gear 62, a first output gear 63, and a planetary gear 67. The first input gear 62 has a receiving portion (holding portion) 62c that receives (holds) the planetary gear 67. The receiving portion 62c is composed of an idling portion 62a and a locking portion 62b. The idling portion 62a is a recess that is recessed radially inward. The planetary gear 67 is held by sliding contact with the idling portion 62a, allowing the planetary gear 67 to rotate idly. The locking portion 62b has an edge that meshes with the teeth of the planetary gear 67 to suppress the rotation of the planetary gear 67. Moreover, the first output gear 63 has a first spur gear portion 63a (hereinafter, first gear portion 63a), a second spur gear portion 63b (hereinafter, second gear portion 63b), and an internal gear 63c that meshes with the planetary gear 67. With the above configuration, the one-way clutch 72 transmits the rotation in the solid line direction in FIG. 4(b) input to the first input gear 62 to the first output gear 63, but does not transmit the drive to the first output gear 63 when the rotation in the dotted line direction in FIG. 4(b) is input to the first input gear 62.

[0021] 5(a) and 5(b), the one-way clutch 73 is made up of a second input gear 64, a second output gear 65, and a planetary gear 68. Like the one-way clutch 72, the one-way clutch 73 also transmits rotation in the direction of the solid line in FIG. 5(b) that is input to the second input gear 64 to the second output gear 65, but does not transmit drive to the second output gear 65 when rotation in the direction of the dotted line in FIG. 5(b) is input to the second input gear 64.

[0022] The one-way clutch 72 and the one-way clutch 73 used in this embodiment are not limited to the above configuration, and may be any mechanism that transmits drive in only one direction, such as a spring clutch or a ratchet.

[0023] 6 and 7 are diagrams for explaining the gear rotation direction and the drive transmission path in this embodiment. A one-way rotation mechanism combining a one-way clutch 72 and a one-way clutch 73 will be explained. The first input gear 62 of the one-way clutch 72 meshes with an intermediate input gear 61 and a second input gear 64 of the one-way clutch 73. The intermediate roller input gear 66 meshes with a first output gear 63 of the one-way clutch 72 and a second output gear 65 of the one-way clutch 73.

[0024] FIG. 6 is a diagram showing a path of drive transmission when the conveying roller 32 rotates forward (second conveying state). When the conveying roller 32 rotates forward, the intermediate input gear 61 rotates clockwise. In response to the clockwise rotation of the intermediate input gear 61, the first input gear 62 of the one-way clutch 72 rotates counterclockwise, and the second input gear 64 of the one-way clutch 73 rotates clockwise. At this time, in the one-way clutch 73, the clockwise rotation input to the second input gear 64 is transmitted to the second output gear 65. When the second output gear 65 rotates clockwise, it rotates the intermediate roller input gear 66 counterclockwise, causing the intermediate roller 28 to rotate forward. Therefore, when the conveying roller 32 rotates forward, the intermediate roller 28 rotates forward, and the sheet P can be conveyed in the conveying direction. At this time, the counterclockwise rotation of the intermediate roller input gear 66 causes the first output gear 63 to rotate clockwise, but the first input gear 62 is rotating counterclockwise and the drive of the first input gear 62 and the first output gear 63 is cut off, so they can rotate in different directions.

[0025] As shown in FIG. 7, when the conveying roller 32 rotates in the reverse direction (first conveying state), the intermediate input gear 61 rotates counterclockwise. In response to the counterclockwise rotation of the intermediate input gear 61, the first input gear 62 of the one-way clutch 72 rotates clockwise, and the second input gear 64 of the one-way clutch 73 rotates counterclockwise. At this time, in the one-way clutch 72, the clockwise rotation input to the first input gear 62 is transmitted to the first output gear 63. When the first output gear 63 rotates clockwise, it rotates the intermediate roller input gear 66 counterclockwise, causing the intermediate roller 28 to rotate forward. Therefore, even when the conveying roller 32 rotates in the reverse direction, the intermediate roller 28 rotates forward, and the sheet P can be conveyed in the conveying direction. In addition, the counterclockwise rotation of the intermediate roller input gear 66 at this time Due to the rotation of the second input gear 64, the second output gear 65 rotates clockwise, but the second input gear 64 rotates counterclockwise, and since the drive of the second input gear 64 and the second output gear 65 is cut off, they can rotate in different rotational directions.

[0026] With the above-described configuration, a mechanism can be realized in which the intermediate rollers 28 rotate in the forward direction regardless of the rotation direction of the transport rollers 32.

[0027] 8 is a diagram showing the drive configuration of the conveying section in this embodiment. The regulating gear 69 (second gear) is disposed in a receiving section (holding section) 71c provided on the base member 71. The one-way clutch 72 is fitted to a shaft section 71e provided on the base member 71, and a first gear section 63a (first gear section) provided on the first output gear 63 (first gear) meshes with the regulating gear 69 (second gear). In addition, the first output gear 63 is connected (drivingly coupled) to the intermediate roller 28 (first conveying roller) via the intermediate roller input gear 66.

[0028] 9 to 11 are diagrams showing the drive direction and the state of the second gear in this embodiment. A state in which the rotation direction of the first output gear 63 (first gear) is restricted depending on the state of the regulating gear 69 (second gear) will be described.

[0029] 9, the intermediate roller 28 rotates in the paper transport direction. At this time, the regulating gear 69 is held to rotate around the rotation center 1 and rotates in the A' direction due to sliding contact between the tooth tip of the regulating gear 69 and the idling portion 71a. In addition, since the locking portion 71b is provided outside the tooth tip circle of the regulating gear 69, it does not impede the rotation of the regulating gear 69 when it rotates around the rotation center 1.

[0030] As shown in FIG. 9, the radius of the pitch circle of the first gear portion 63a is r1, the radius of the pitch circle of the regulating gear 69 is r2, the radius of the tip circle of the regulating gear 69 is r3, and the clearance provided between the pitch circle of the first gear portion 63a and the pitch circle of the regulating gear 69 is CL. By providing this clearance CL, it is possible to set a backlash between the first gear portion 63a and the regulating gear 69. The position of the rotation center 1 is arranged on a circle having a radius of r1+r2+CL from the rotation center 3, and the arc of the idling portion 71a is preferably arranged to coincide with the arc of radius r3 from the rotation center 1. With the above configuration, the first gear portion 63a and the regulating gear 69 rotate while maintaining an appropriate backlash between their axes, so that the driving load by the regulating gear 69 can be reduced.

[0031] Furthermore, if the central angle θ1 of the arc of the idling portion 71a is too large, it may get caught on the tooth tip of the regulating gear 69 and prevent rotation in the A' direction. The sliding resistance of the regulating gear 69 also increases. On the other hand, if it is too small, it may get caught between adjacent teeth of the regulating gear 69, making it impossible to maintain the position of the regulating gear 69. Therefore, it is preferable that the angle θ1 be greater than or equal to Z1 / 360 and less than or equal to 90° (Z1 is the number of teeth of the regulating gear 69).

[0032] When the intermediate roller 28 rotates in the reverse direction due to the occurrence of some load, the first output gear 63 rotates in the rotation direction B (second direction) shown in Fig. 10. At this time, the rotation center (rotation axis) of the regulating gear 69 moves from rotation center 1 to rotation center 2. When the rotation center of the regulating gear 69 moves to rotation center 2, the locking portion 71b enters within the tip circle diameter of the regulating gear 69, so that the regulating gear 69 is locked with the locking portion 71b and prevented from rotating in the B' direction. This prevents the intermediate roller 28 from rotating in the reverse direction.

[0033] That is, the receiving portion (holding portion) 71c holds the regulating gear 69 (second gear) so that the rotation direction of the regulating gear 69 is regulated so that the regulating gear 69 is allowed to rotate only in one direction. The regulating gear 69 is held in the receiving portion 71c so as to be displaceable around the rotation axis of the first output gear 63 (first gear), and can be held in either a state in which it is rotatable in the idling portion 71a or a state in which its rotation is regulated by the locking portion 71b. That is, the regulating gear 69 is a gear that is not journaled within the device, and the rotation axis of the gear is not fixed to a single line.

[0034] An angle θ4 is defined as an angle formed by a line (imaginary line segment) connecting the rotation center 3, which is the rotation center of the first output gear 63, and the rotation center 2 of the regulating gear 69, and a line (imaginary line) extending from the rotation center 2 and passing through the locking portion 71b. By setting the angle θ4 to 90° or more, a reaction force generated in the regulating gear 69 when the regulating gear 69 is locked is generated toward the rotation center 3, and the regulating gear 69 can be locked with a stronger force.

[0035] As shown in FIG. 11, the locking portion 71b has an edge portion 71b1, a first flat portion 71b2 continuous with the edge portion 71b1, and a second flat portion 71b3 continuous with the edge portion 71b1 on the opposite side to the first flat portion 71b2. When viewed in the direction of the rotation axis of the first output gear 63, the locking portion 71b is arranged so that the first flat portion 71b2 and the second flat portion 71b3 are continuous with each other to form an angle θ2 via the edge portion 71b1. The relationship between the angle θ2 of the locking portion 71b and the angle θ3 between the tangents passing through the contact points with the locking portion 71b at the tips of adjacent teeth of the regulating gear 69 is preferably θ2≦θ3. With the above configuration, the regulating gear 69 is easily locked to the locking portion 71b when preventing the intermediate roller 28 from rotating in reverse.

[0036] Fig. 12 is a diagram showing the arrangement of the second gear in this embodiment. As shown in Fig. 12, when viewed in the direction of the rotation axis of the first output gear 63, an intermediate roller input gear 66 (third gear) that meshes with the first output gear 63 downstream of the first output gear 63 in the drive train is arranged so that its height in the Z direction (vertical position) is higher than that of the first output gear 63. In addition, a regulating gear 69 is a gear smaller than the first output gear 63, and is arranged so that it is substantially opposite to the intermediate roller input gear 66 when viewed in the direction of the rotation axis, and its height in the Z direction is lower than the rotation center of the first output gear 63.

[0037] When the regulating gear 69 is locked by the locking portion 71b, the rotation moment of the first gear portion 63a is converted into a force that moves the first gear portion 63a in the direction of the arrow C with the locking portion 71b as the center of rotation. The regulating gear 69 is preferably disposed on the negative Y-direction side (upstream in the reverse direction) of a straight line 2 that is a virtual line passing through the center of the first gear portion 63a (first output gear 63) and the center of the intermediate roller input gear 66. According to the above configuration, the force that the first gear portion 63a receives is generated in a direction that does not change the axis distance with the intermediate roller input gear 66, or in a direction that reduces the axis distance. This makes it possible to prevent an increase in backlash that occurs due to the widening of the axis distance between the first output gear 63 and the intermediate roller input gear 66, and to reduce the amount of reverse rotation of the conveying roller 32 until the regulating gear 69 is locked.

[0038] In addition, by positioning the regulating gear 69 above straight line 1, which is a tangent to the Z-direction lower end (lowest end) of the tooth tip circle of the first gear portion 63a, the regulating gear 69 can be positioned without increasing the size of the device in the Z direction.

[0039] It is also preferable to locate the locking portion 71b below in the Z direction from the rotation center of the regulating gear 69. When the regulating gear 69 moves from the rotation center 1 when idling to the rotation center 2 when locked, the regulating gear 69 moves more easily due to its own weight, so that the amount of reverse rotation of the conveying roller until the regulating gear 69 is locked can be reduced.

[0040] FIG. 13 is a cross-sectional view of the space in which the regulating gear 69 is received. It is a view of the cross section of the solid line in FIG. 12, viewed from the upstream side in the Y direction. The regulating gear 69 has a sliding surface 69a that slides against the first input gear 62, and a sliding surface 69b that slides against the base member 71. The regulating gear 69 is received between the base member 71 and the first input gear 62, and is free to move in the X direction. When the regulating gear 69 is tilted (the state of the regulating gear 69' shown in FIG. 13), the tips of the teeth of the regulating gear 69 Before hitting the tooth bottom portion 63e of the first gear, the sliding surface 69a hits the first input gear 62. As a result, the regulating gear 69 is tilted, and it is possible to prevent an increase in the driving load of the regulating gear 69 caused by being pinched between the idling portion 71a and the tooth bottom portion 63e of the first output gear 63.

[0041] 14(a) to 14(d) are diagrams showing a first registration operation of the image recording device in this embodiment. As shown in FIG. 14(a), the sheet P fed by the feed roller 25 provided in the feed unit 2 is conveyed in the conveying direction by the rotation of a roller pair consisting of an intermediate roller 28 and a driven roller 29 that receives a biasing force and comes into contact with the intermediate roller 28. At this time, the drive transmission path is as shown in FIG. 7, the conveying roller 32 (second roller) rotates in the reverse direction, and the intermediate roller 28 (first roller) rotates in the forward direction. When the conveying of the sheet P progresses and the leading edge of the sheet P reaches the conveying roller 32, the conveying roller 32 rotates in the reverse direction, so that the leading edge of the sheet P cannot advance further downstream in the conveying direction than the conveying roller 32 and is stopped by the conveying roller 32 and the pinch roller 33. Meanwhile, the intermediate roller 28 tries to convey the sheet P in the conveying direction, so that the sheet P forms a loop as shown in FIG. 14(b). As a result, even if the timing at which the left and right leading edges of the sheet P reach the transport rollers 32 differs, the positions of the left and right leading edges can be aligned.

[0042] After forming the loop and aligning the left and right leading ends of the sheet P, the rotation direction of the conveying roller 32 is changed as shown in Fig. 14(c). Since the drive transmission path changes from the state shown in Fig. 7 to the state shown in Fig. 6, the drive to the intermediate roller 28 is temporarily cut off, and the drive is reconnected after consuming backlash in the drive train, a transmission delay of the one-way clutch, and the like.

[0043] However, when a loop is formed, a force that tries to eliminate the loop acts on the sheet P, so the intermediate roller 28 receives a force from the sheet P in a direction that causes it to rotate in reverse. If the intermediate roller 28 rotates in reverse at this time, the loop is eliminated, and the left and right leading edges that were once aligned may become misaligned again. Therefore, when conveying the sheet P after the left and right leading edges are aligned, it is important to prevent the intermediate roller 28 from rotating in reverse and to maintain the loop until conveyance by the conveyance roller 32 begins.

[0044] In this embodiment, when the intermediate roller 28 tries to rotate in the reverse direction, as shown in Fig. 10, the regulating gear 69 engages with the engaging portion 71b to prevent the intermediate roller 28 from rotating in the reverse direction. This makes it possible to hold the loop of the sheet P even when the drive to the intermediate roller 28 is cut off.

[0045] 14(d), when the conveyance roller 32 starts conveying the sheet P and the drive to the intermediate roller 28 is connected again, as shown in FIG. 9, the regulating gear 69 comes into sliding contact with the idling portion 71a and does not hinder the rotation of the intermediate roller 28. In addition, by making the roller circumferential speed of the conveyance roller 32 faster than the roller circumferential speed of the intermediate roller 28, the flexure of the sheet is naturally eliminated as the conveyance of the sheet progresses, and it is possible to suppress the reaction force due to the flexure from interfering with the sheet conveyance.

[0046] With the above-described configuration, it is possible to prevent the intermediate roller 28 from rotating in the reverse direction due to the reaction force generated when the sheets P are registered, without using a biasing means such as a spring.

[0047] 15(a) to 15(d) are diagrams showing a second registration adjustment operation of the recording device in this embodiment. Note that this registration adjustment operation is a transport operation in which the transport roller 32 is momentarily (temporarily) reversed, utilizing the period during which the drive to the intermediate roller 28 is cut off when the rotation direction of the transport roller 32 is switched. In other words, after the rotation direction of the transport roller 32 is switched from forward to reverse, the intermediate roller 28, which has been in a drive-cut state, reverses the rotation direction of the transport roller 32 before the drive is reconnected due to backlash in the drive train or transmission delay of the one-way clutch, etc. Switch from forward to forward rotation.

[0048] As shown in FIG. 15(a), the sheet P is conveyed in the conveying direction by the rotation of the roller pair of the intermediate roller 28 and the driven roller 29 provided with a biasing force. After the leading edge of the sheet P moves a certain amount downstream in the conveying direction from the conveying roller 32, the conveying roller 32 changes its rotation direction to the reverse direction, and conveyance of the sheet P to the upstream side in the conveying direction is started. At this time, the intermediate roller 28 is prevented from rotating in the reverse direction by the engagement of the regulating gear 69 and the engagement part 71b. The part of the sheet P that is sandwiched between the intermediate roller 28 and the driven roller 29 is held without being reversed, and the leading edge is conveyed upstream in the conveying direction by the reverse rotation of the conveying roller 32. Therefore, as shown in FIG. 15(b), the sheet P forms a loop between the conveying roller 32 and the intermediate roller 28. This allows the left and right leading edges of the sheet P to be aligned. In addition, by forming a loop by the reverse rotation of the conveying roller 32 after the leading edge of the sheet P is conveyed a certain amount downstream in the conveying direction from the conveying roller 32, there are advantages such as reducing damage to the leading edge of the paper and adjusting the loop amount.

[0049] After the left and right leading ends of the sheet P are aligned by the loop, the conveying direction of the conveying rollers 32 is changed back to normal as shown in Fig. 15(c) to resume conveying the sheet P. At this time, the drive to the intermediate roller 28 remains disconnected, but the regulating gear 69 is engaged with the engaging portion 71b, so that the loop can be maintained. As shown in Fig. 15(d), when conveying of the sheet P is started by the conveying rollers 32 and the drive to the intermediate roller 28 is again connected, the regulating gear 69 comes into sliding contact with the idling portion 71a and does not impede the rotation of the intermediate roller 28.

[0050] With the above-described configuration, even if the driving direction of the transport rollers 32 is switched multiple times during loop formation, the state in which the intermediate rollers 28 are prevented from rotating in the reverse direction can be continuously maintained.

[0051] The disclosure of the embodiments of the present invention includes the following configurations. (Configuration 1) a first roller that rotates in a forward direction to transport the sheet in a transport direction; a first gear that transmits driving force to the first roller; A second gear that meshes with the first gear; an idling portion in which the second gear can idly rotate; a locking portion that locks the second gear so as to restrict rotation of the second gear when the first gear receives a force that rotates the first roller in a second direction opposite to a first direction in which the first roller rotates in the forward rotation direction; A recording device comprising: (Configuration 2) 2. The recording apparatus according to configuration 1, wherein the engaging portion is provided downstream in the second direction with respect to the idling portion. (Configuration 3) 3. The recording device according to claim 1, wherein the second gear is engaged with the engaging portion by a force received from the first gear when the first gear rotates in the second direction. (Configuration 4) The recording device according to any one of configurations 1 to 3, wherein the second gear rotates in the idling portion due to a force received from the first gear when the first gear rotates in the first direction. (Configuration 5) The recording device according to any one of configurations 1 to 4, wherein the second gear is held by the holding portion so that the center of rotation of the second gear can be displaced around the axis of rotation of the first gear. (Configuration 6) A drive train that transmits driving force to the first roller is provided downstream of the first gear. It has a third gear that meshes with the The recording device described in any one of configurations 1 to 5, characterized in that, when viewed in the direction of the rotation axis of the first gear, the second gear is located upstream in the second direction with respect to a virtual line passing through the rotation center of the third gear and the rotation center of the first gear. (Configuration 7) The recording device according to any one of configurations 1 to 6, wherein the second gear is arranged so that its vertical position is below the rotation axis of the first gear and above the lowest end of the gear portion of the first gear with which the second gear meshes. (Configuration 8) The recording device according to any one of configurations 1 to 7, wherein the locking portion is disposed so that its position in the vertical direction is lower than the center of rotation of the second gear. (Configuration 9) The recording apparatus according to any one of configurations 1 to 8, wherein the second gear is smaller than the first gear. (Configuration 10) 10. The recording apparatus according to any one of configurations 1 to 9, wherein the second gear is a gear that is not supported by a shaft. (Configuration 11) a second roller provided downstream of the first roller in a sheet conveying path, The recording device according to any one of configurations 1 to 10, wherein the peripheral speed of the second roller when rotating in the forward rotation direction is faster than the peripheral speed of the first roller when rotating in the forward rotation direction. (Configuration 12) a recording unit that records an image on a sheet; A conveying unit that conveys a sheet; A recording device comprising: The conveying unit is the first roller and the second roller are disposed upstream of the recording unit in a sheet transport path; A driving source; a drive train including the first gear and configured to transmit a driving force of the drive source to each of the first roller and the second roller; Equipped with a first conveying state in which the first roller is rotated in the forward rotation direction and the second roller is rotated in a reverse direction opposite to the forward rotation direction; a second conveying state in which the first roller and the second roller are rotated in the forward rotation direction; 12. The recording apparatus according to claim 11, wherein the recording apparatus is configured to be capable of taking the above-mentioned steps. (Configuration 13) The first gear is a first gear portion with which the second gear meshes; a second gear portion that meshes with a gear included in the drive train; 13. The recording device according to claim 12, further comprising: (Configuration 14) 14. The recording apparatus according to claim 12, wherein the driving source is a single motor. (Configuration 15) Any of configurations 12 to 14, characterized in that after the rotation direction of the first roller is switched from the forward rotation direction to the reverse rotation direction, the rotation direction of the first roller is switched from the reverse rotation direction to the forward rotation direction before the second roller starts rotating in the forward rotation direction from a drive-disconnected state. A recording device according to any one of the preceding configurations. [Explanation of symbols]

[0052] 28... intermediate roller (first roller), 31... conveying motor, 32... conveying roller (second roller), 71... drive base, 71a... idling portion, 71b... engaging portion, 71c... receiving portion (holding portion), 63... first output gear (first gear), 69... regulating gear (second gear), P... recording medium (sheet)

Claims

1. a first roller that rotates in a forward direction to convey the sheet in a conveyance direction; a first gear that transmits driving force to the first roller; a second gear that meshes with the first gear; an idling portion in which the second gear can idly rotate; a locking portion that locks the second gear so as to restrict rotation of the second gear when the first gear receives a force that rotates the first roller in a second direction opposite to the first direction that rotates the first roller in the forward rotation direction; a third gear that meshes with the first gear downstream of the first gear in a drive train that transmits driving force to the first roller; Equipped with the second gear is disposed upstream in the second direction with respect to an imaginary line passing through the center of rotation of the third gear and the center of rotation of the first gear when viewed in the direction of the rotation axis of the first gear.

2. 2. The recording apparatus according to claim 1, wherein the engaging portion is provided downstream in the second direction from the idling portion.

3. 3. The recording apparatus according to claim 2, wherein the second gear is locked by the locking portion due to a force received from the first gear when the first gear rotates in the second direction.

4. 2. The recording apparatus according to claim 1, wherein the second gear rotates in the idling portion due to a force received from the first gear when the first gear rotates in the first direction.

5. 2. The recording apparatus according to claim 1, wherein the second gear is held so that its center of rotation can be displaced around the rotation axis of the first gear.

6. 2. The recording device according to claim 1, wherein the second gear is positioned so that its vertical position is below the rotation axis of the first gear and above the lowest end of the gear portion of the first gear with which the second gear meshes.

7. 7. The recording apparatus according to claim 6, wherein the engaging portion is disposed so that its position in the vertical direction is lower than the center of rotation of the second gear.

8. 2. The recording apparatus according to claim 1, wherein the second gear is smaller than the first gear.

9. 2. The recording apparatus according to claim 1, wherein the second gear is a gear that is not supported by a shaft.

10. a second roller provided downstream of the first roller in a sheet conveyance path; 2. The recording apparatus according to claim 1, wherein the peripheral speed of the second roller when rotating in the forward direction is faster than the peripheral speed of the first roller when rotating in the forward direction.

11. a recording unit that records an image on a sheet; a conveying unit that conveys a sheet; A recording device comprising: The conveying unit is the first roller and the second roller are disposed upstream of the recording unit in a sheet transport path; A driving source; a drive train including the first gear and configured to transmit the driving force of the drive source to each of the first roller and the second roller; Equipped with a first conveying state in which the first roller is rotated in the forward rotation direction and the second roller is rotated in a reverse direction opposite to the forward rotation direction; a second conveying state in which the first roller and the second roller are rotated in the forward direction; 11. The recording apparatus according to claim 10, wherein the recording apparatus is configured to be capable of taking the following two conditions:

12. The first gear is a first gear portion with which the second gear meshes; a second gear portion that meshes with a gear included in the drive train; 12. The recording device according to claim 11, further comprising:

13. 12. The recording apparatus according to claim 11, wherein the driving source is a single motor.

14. 12. The recording device according to claim 11, wherein after the rotation direction of the first roller is switched from the forward direction to the reverse direction, the rotation direction of the first roller is switched from the reverse direction to the forward direction before the second roller starts rotating in the forward direction from a drive-disconnected state.

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