Power transmission device, medium transport device, and recording apparatus

Abstract

When the planetary gear mechanism is used in order to make the center distance between the two gears appropriate, a space for installing the planetary gear mechanism is liable to become large, so that there is a liability that upsizing of the image forming apparatus is caused.SOLUTION: The power transmission device comprises a first gear provided on a first rotary shaft, a second gear provided on a second rotary shaft and meshing with the first gear, a first support portion for supporting the first rotary shaft, and a second support portion for supporting the second rotary shaft, wherein the second support portion allows movement of the second rotary shaft in a direction in which the second gear moves back and forth with respect to the first gear, and a force acting in a direction toward the first gear acts on the second gear.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a power transmission device for transmitting power, a medium transport device including the same, and a recording device including the medium transport device. [Background technology]

[0002] In a device that transmits power using two meshing gears, such as the drive device described in Patent Document 1, the distance between the axes of the two meshing gears is important. In this specification, the "inter-axis distance" refers to the distance between the centers of the rotation axes of the two gears. If the inter-axis distance is shorter than the appropriate value, it may result in damage to the gears or an increase in the drive load. Conversely, if the inter-axis distance is longer than the appropriate value, it may result in insufficient power transmission and reduced durability due to a lower meshing ratio. To solve this problem, a planetary gear mechanism is sometimes used to press one gear against the other. This configuration prevents the center distance from becoming longer than the appropriate value, and even if the center distance becomes shorter, the pressing force will cause one gear to press against the other gear, preventing damage to the gears and an increase in drive load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-142038 Summary of the Invention [Problem to be solved by the invention]

[0004] A planetary gear mechanism tends to require a large installation space, which may lead to an increase in the size of the device. [Means for solving the problem]

[0005] In order to solve the above problem, the power transmission device of the present invention has a first gear provided on a first rotating shaft, a second gear provided on a second rotating shaft and meshing with the first gear, a first support part that supports the first rotating shaft, and a second support part that supports the second rotating shaft, wherein the second support part allows movement of the second rotating shaft in a direction in which the second gear moves forward and backward relative to the first gear, and a force acts on the second gear in a direction toward the first gear.

[0006] The media transport device of the present invention is characterized by including the power transmission device and a feed roller that receives power from the second gear via the first gear and rotates to feed the media. The recording apparatus of the present invention is characterized by comprising the medium transport device and a recording section that performs recording on the medium transported by the medium transport device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing the entire medium transport path in the printer. [Figure 2] FIG. 1 is a perspective view of a motor fixing frame attached to a mounting frame. [Figure 3] FIG. 4 is a cross-sectional view of the mounting frame and the motor fixing frame. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 2 is a plan view of a schematic diagram of the power transmission device. [Figure 7] FIG. 2 is a diagram showing the meshing portion of the first gear and the second gear. [Figure 8] 10A and 10B are diagrams showing examples of the arrangement of a second gear relative to a first gear. [Figure 9] 10A and 10B are diagrams showing examples of the arrangement of a second gear relative to a first gear. [Figure 10] 10A and 10B are diagrams showing examples of the arrangement of a second gear relative to a first gear. [Figure 11] 10A and 10B are diagrams showing examples of the arrangement of a fourth gear relative to a third gear. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be briefly described below. A power transmission device according to a first aspect includes a first gear provided on a first rotating shaft, a second gear provided on a second rotating shaft and meshing with the first gear, a first support portion supporting the first rotating shaft, and a second support portion supporting the second rotating shaft, wherein the second support portion allows movement of the second rotating shaft in a direction in which the second gear moves forward and backward relative to the first gear, and a force acts on the second gear in a direction toward the first gear.

[0009] According to this aspect, the second support portion allows the second rotation shaft to move in a direction in which the second gear advances and retreats relative to the first gear, and a force acts on the second gear in a direction toward the first gear. This allows a space-saving configuration for the second gear to advance and retreat relative to the first gear, thereby preventing the device from becoming larger. Furthermore, proper meshing between the first gear and the second gear can be achieved, thereby achieving proper power transmission.

[0010] A second aspect is an aspect dependent on the first aspect, and is characterized in that it includes a pressing member that presses the second rotating shaft toward the first rotating shaft, and when the second rotating shaft is pressed by the pressing member, a force acts on the second gear in a direction toward the first gear.

[0011] According to this aspect, by pressing the second rotation shaft toward the first rotation shaft with the pressing member, it is possible to appropriately maintain the meshing between the first gear and the second gear.

[0012] The third aspect is a dependent aspect of the first aspect, characterized in that a force acts on the second gear in a direction toward the first gear due to the weight of the second rotating shaft and the weight of the second gear.

[0013] According to this aspect, a force acting on the second gear in a direction toward the first gear is caused by the weight of the second rotating shaft and the weight of the second gear, so there is no need for a dedicated component, such as a spring, to act on the second gear in a direction toward the first gear, or even if a spring is used, only a small spring force is required, allowing for a smaller and less expensive device.

[0014] A fourth aspect is an aspect dependent on the first aspect, characterized in that, when viewed from the axial direction of the first rotating shaft, a first line passing through a first axis center of the first rotating shaft and a second axis center of the second rotating shaft is non-parallel to the advancing direction of the second gear toward the first gear, and a second line is a line passing through the first axis center and parallel to the advancing direction, and the second axis center is located in the direction of the reaction force that the second gear receives from the first gear, relative to the second line.

[0015] According to this aspect, the second axis center is located in the direction of the reaction force that the second gear receives from the first gear relative to the second straight line, so that the magnitude of the component of the reaction force that the second gear receives from the first gear is small even if it acts in the direction in which the second gear advances toward the first gear or in the direction opposite to the direction in which the second gear advances toward the first gear. This makes it possible to appropriately maintain meshing between the first gear and the second gear. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to the second or third aspect.

[0016] A fifth aspect is an aspect dependent on the fourth aspect, characterized in that, when viewed from the axial direction of the first rotation shaft, a first line passing through a first axis center of the first rotation shaft and a second axis center of the second rotation shaft is non-parallel to the direction of advancement and retreat of the second gear, and a component of the reaction force that the second gear receives from the first gear acts in a direction in which the second gear advances toward the first gear.

[0017] According to this aspect, the component of the reaction force that the second gear receives from the first gear at the pitch point where the teeth of the first gear and the teeth of the second gear contact acts in a direction in which the second gear advances toward the first gear, so that the meshing between the first gear and the second gear can be properly maintained compared to when the component force acts in a direction in which the second gear retreats from the first gear. The reaction force that the second gear receives from the first gear is a reaction force that the second gear receives at a pitch point where the teeth of the first gear and the teeth of the second gear meet, and is a reaction force that acts along the normal direction of the tooth surface of the second gear at the pitch point.

[0018] A sixth aspect is an aspect dependent on the fourth aspect, characterized in that, when viewed from the axial direction of the first rotating shaft, an angle formed by a first line passing through a first axis center of the first rotating shaft and a second axis center of the second rotating shaft and a direction of advancement and retreat of the second gear is greater than a pressure angle of the second gear and smaller than 90°, and an angle formed by a reaction force received by the second gear from the first gear and a direction in which the second gear advances toward the first gear is an acute angle.

[0019] According to this aspect, the angle formed by the reaction force that the second gear receives from the first gear at the pitch point where the teeth of the first gear and the teeth of the second gear contact each other and the direction in which the second gear advances into the first gear is acute, so that a component of the reaction force that the second gear receives from the first gear acts in the direction in which the second gear advances into the first gear, thereby making it possible to appropriately maintain meshing between the first gear and the second gear. The reaction force that the second gear receives from the first gear is a reaction force that the second gear receives at a pitch point where the teeth of the first gear and the teeth of the second gear meet, and is a reaction force that acts along the normal direction of the tooth surface of the second gear at the pitch point.

[0020] The seventh aspect is an aspect dependent on the fourth aspect, and is characterized in that, when viewed from the axial direction of the first rotation shaft, the angle formed between the first straight line and the advance / retreat direction of the second gear is equal to the pressure angle of the second gear.

[0021] According to this aspect, the angle between the first line and the direction of advancement and retreat of the second gear is equal to the pressure angle of the second gear, so that the reaction force that the second gear receives from the first gear is perpendicular to the direction of advancement and retreat of the second gear, thereby preventing the reaction force from adversely affecting the force acting in the direction of the second gear toward the first gear.

[0022] An eighth aspect is an aspect dependent on the first aspect, characterized in that the first gear has a first flange portion coaxial with the first gear, the second gear has a second flange portion coaxial with the second gear, the sum of the diameters of the first flange portion and the second flange portion is smaller than the sum of the diameters of the tip circles of the first gear and the tip circles of the second gear and is larger than the sum of the diameters of the root circles of the first gear and the root circles of the second gear, and the second flange portion abuts against the first flange portion due to a force acting on the second gear in a direction toward the first gear.

[0023] According to this aspect, the second flange portion abuts against the first flange portion due to a force acting on the second gear in a direction toward the first gear, so that the axial distance between the first rotation shaft and the second rotation shaft is appropriately maintained, and the first gear and the second gear can appropriately mesh with each other. In particular, even if a force acting on the second gear in a direction toward the first gear is large, the first gear and the second gear can appropriately mesh with each other. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to any of the second to seventh aspects.

[0024] A ninth aspect is a dependent aspect of the eighth aspect, and is characterized in that it has a clutch that switches between connecting and disconnecting power transmission between the first gear and the first rotating shaft, and the housing of the clutch also serves as the first flange portion.

[0025] According to this aspect, the housing of the clutch also serves as the first flange portion, so there is no need to provide the first flange portion as a dedicated member, and the device can be made smaller and less expensive.

[0026] A tenth aspect is an aspect dependent on the first aspect, characterized in that the second support portion is configured as an aligning bearing. According to this aspect, since the second support portion is configured as an aligning bearing, it is possible to easily obtain a configuration that allows movement of the second rotation shaft in the direction in which the second gear advances and retreats relative to the first gear. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to any of the second to ninth aspects.

[0027] An eleventh aspect is a dependent aspect of the first aspect, characterized in that the second support portion is a bearing portion that receives the second rotating shaft and is supported by a frame, and the bearing portion has play between itself and the frame, thereby allowing movement of the second rotating shaft in the direction in which the second gear moves forward and backward relative to the first gear.

[0028] According to this aspect, by providing play between the bearing portion and the frame, movement of the second rotation axis in the direction in which the second gear moves forward and backward relative to the first gear is permitted, so the second support portion can be constructed at low cost. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to any of the second to ninth aspects.

[0029] A twelfth aspect is characterized in that, in any of the first to eleventh aspects, the gear further includes a third gear provided on a third rotating shaft, and a fourth gear that is a gear provided on the second rotating shaft at an axial distance from the second gear and meshes with the third gear, and when viewed from the axial direction of the third rotating shaft, the direction of advancement and retreat of the second gear is along a direction perpendicular to a straight line passing through the axial center of the second rotating shaft and the axial center of the third rotating shaft.

[0030] When the second rotating shaft moves so that the second gear moves toward or away from the first gear, the fourth gear provided on the second rotating shaft also displaces, which may result in improper meshing between the third gear and the fourth gear. However, according to this aspect, the direction of movement of the second gear, as viewed from the axial direction of the third rotation shaft, is perpendicular to a line passing through the axial center of the second rotation shaft and the axial center of the third rotation shaft, which makes it possible to suppress a change in the inter-axial distance between the third rotation shaft and the second rotation shaft even when the second rotation shaft moves, thereby suppressing improper meshing between the third gear and the fourth gear.

[0031] A thirteenth aspect is characterized in that, in any of the first to eleventh aspects, the device further includes a third gear provided on a third rotating shaft, and a fourth gear that is a gear provided on the second rotating shaft at an axial distance from the second gear and meshes with the third gear, the second support portion is located between the second gear and the fourth gear in the axial direction of the second rotating shaft, and the distance between the fourth gear and the second support portion is shorter than the distance between the second gear and the second support portion.

[0032] According to this aspect, the second support portion is located between the second gear and the fourth gear in the axial direction of the second rotation shaft, and the distance between the fourth gear and the second support portion is shorter than the distance between the second gear and the second support portion, so that when the second rotation shaft moves around the second support portion as a fulcrum, the displacement of the fourth gear can be suppressed compared to the displacement of the second gear, thereby suppressing improper meshing between the third gear and the fourth gear. This aspect may be subordinate to the twelfth aspect.

[0033] The media conveying device of the 14th aspect is characterized by comprising the power transmission device of the first aspect and a feed roller that receives power from the second gear via the first gear and rotates to feed the media. According to this aspect, the medium transport device can achieve the same effects as the first aspect described above. It should be noted that this aspect is not limited to the power transmission device according to the first aspect, but may include the power transmission device according to any one of the second to thirteenth aspects.

[0034] A fifteenth aspect is an aspect dependent on the fourteenth aspect, and is characterized in that the apparatus further comprises a medium support section that supports the medium before feeding, and the feed roller feeds the medium from the medium support section. According to this aspect, in a configuration in which the feed roller feeds the medium from the medium support section, the effects of the above-described fourteenth aspect can be obtained.

[0035] A recording device according to a sixteenth aspect is characterized by comprising a medium conveying device according to the fourteenth or fifteenth aspect, and a recording unit that records on the medium conveyed by the medium conveying device. According to this aspect, the recording device can achieve the effects of the fourteenth or fifteenth aspect described above.

[0036] The present invention will be specifically described below. In the following, an inkjet printer 1 that performs recording by ejecting ink, which is an example of a liquid, onto a medium such as recording paper will be described as an example of a recording device. In the following, the inkjet printer 1 will be abbreviated as printer 1. The recording device is not limited to an inkjet printer, and may be a laser printer, a dot impact printer, a thermal printer, or any other suitable printer.

[0037] The XYZ coordinate system shown in each figure is a Cartesian coordinate system, with the Y axis direction being the media width direction that intersects with the media transport direction and the device depth direction. In this embodiment, of the side surfaces that make up the periphery of the housing 2, the side surface in the +Y direction is the back surface, and the side surface in the -Y direction is the front surface. The X axis direction is the width direction of the device, with the +X direction being the left side and the -X direction being the right side as seen by the operator of the printer 1. The -X direction is also the direction in which media is fed out from each media cassette, which will be described later. The Z-axis direction is the vertical direction, that is, the height direction of the device, with the +Z direction being the upward direction and the -Z direction being the downward direction.

[0038] Below, the direction in which the medium is fed may be referred to as "downstream," and the opposite direction may be referred to as "upstream." In Figure 1, the medium transport path is indicated by a dashed line. In the printer 1, the medium is transported through the transport path indicated by the dashed line. In Figure 1, the symbols T1, T2, T3, T4, T5, and T6 each represent a transport path. Each transport path will be explained later. From the perspective of transporting the medium, the printer 1 can also be called a medium transport device 5. In this case, the printer 1 is an example of a recording device that includes the medium transport device 5 and a line head 12, which will be described later. In particular, the media conveying device 5 is a device that includes a media cassette 3 (described later), a pick roller 21 that feeds media from the media cassette 3, and a power transmission device 50 (see Figure 4) that transmits the power of a motor (not shown) to the pick roller 21.

[0039] The printer 1 has a medium cassette 3 below a housing 2 that includes a line head 12 (described later). The symbol P indicates the medium stored in the medium cassette 3. The medium cassette 3 is an example of a medium support section that supports the medium before it is fed. A pick roller 21 that feeds the stored medium in the −X direction is provided for the medium cassette 3. The pick roller 21 is an example of a feed roller that feeds the medium from the medium cassette 3 by rotating.

[0040] A pair of feeding rollers 25 is provided for the medium cassette 3, which feeds the medium sent out by the pick roller 21 further downstream. Note that a plurality of medium cassettes (not shown) are further provided below the medium cassette 3. A pick roller (not shown) and a pair of feeding rollers (not shown) are provided for each of the plurality of medium cassettes (not shown). Unless otherwise specified, the term "roller pair" hereinafter refers to a pair of rollers consisting of a drive roller driven by a power source such as a motor, and a driven roller that rotates in contact with the drive roller.

[0041] Symbol T1 indicates the transport path, or in other words, the feeding path, of the medium that is sent out from the medium cassette 3 and reaches the transport roller pair 31. The medium sent out from the medium cassette 3 receives a feeding force from the transport roller pairs 29 and 30 and is sent to the transport roller pair 31. In this embodiment, the feeding path T1 is the path from the medium cassette 3 to the transport roller pair 31.

[0042] The medium receiving the feeding force from the transport roller pair 31 is sent to the transport path T2. The transport path T2 is provided with a line head 12, which is an example of a recording unit, and a transport belt 17. The position on the transport path T2 facing the line head 12 is the recording position. In this embodiment, the transport path T2 is a linear path that runs from the transport roller pair 31 to the transport roller pair 32.

[0043] The line head 12 has nozzles 13, and performs recording by ejecting ink from the nozzles 13 onto the medium. In this embodiment, the ink is ejected from the nozzles 13 in the -Z direction. The line head 12 is an ink ejection head in which multiple nozzles 13 that eject ink are arranged to cover the entire area in the medium width direction, and is configured as an ink ejection head that can record across the entire area of ​​the medium width without moving in the medium width direction. However, the ink ejection head is not limited to this, and may be a type that is mounted on a carriage and ejects ink while moving in the medium width direction.

[0044] The line head 12 according to this embodiment ejects ink of a plurality of colors, for example. Specifically, in this embodiment, the plurality of nozzles 13 are configured with a plurality of nozzles 13 that eject yellow ink, a plurality of nozzles 13 that eject magenta ink, a plurality of nozzles 13 that eject cyan ink, and a plurality of nozzles 13 that eject black ink.

[0045] The conveyor belt 17 is an endless belt that is wound around a first roller 18, which is a drive roller, and a second roller 19, which is a driven roller, and is rotated by driving the first roller 18 by a motor (not shown). The medium is conveyed to a position facing the line head 12 while being attracted to the belt surface of the conveyor belt 17. The first roller 18 , the second roller 19 and the conveyor belt 17 constitute a belt unit 16 .

[0046] The medium on which recording has been performed by the line head 12 is sent toward either the transport roller pair 33 or the transport roller pair 39 by the transport roller pair 32 located downstream of the belt unit 16. A switching unit (not shown) for switching the transport path is provided downstream of the transport roller pair 32.

[0047] The medium has a first side and an opposite second side, and assuming that recording is performed first on the first side, when the medium is discharged without recording on the second side, or when the medium is discharged after recording on the second side, the medium is sent to discharge path T6. In this embodiment, discharge path T6 is a path that runs from transport roller pair 32 to transport roller pairs 39, 40, 41, 42, and 43, and then to transport roller pair 44. Discharge path T6 is shaped to curve and invert the medium so that the side that was most recently recorded on is on the inside. The medium sent to the discharge path T6 is discharged face-down toward the discharge tray 8 by the transport roller pair 44. The transport path may further branch off at the discharge path T6. For example, in addition to the path for discharging the medium face-down as shown, a path for discharging the medium face-up to a discharge tray or another device (not shown) may be provided.

[0048] When recording on the second side of the medium, that is, when double-sided recording is performed, the medium is sent to guide path T3. In this embodiment, guide path T3 is a path from transport roller pair 32 to transport roller pair 33. The medium is further sent to switchback path T4 by transport roller pair 33. In this embodiment, switchback path T4 is a path in the +X direction from transport roller pair 33. Switchback path T4 has a shape that curves and inverts the medium with the most recently recorded side facing inward. Switchback path T4 is a path that switches back the medium in order to invert the front and back of the medium that has been recorded on by line head 12. In addition to transport roller pair 33, switchback path T4 is provided with transport roller pair 34. When the medium enters the switchback path T4, the rotation direction of the transport roller pair 33, 34 is switched, and the medium is sent in the -X direction and enters the reversing path T5.

[0049] In this embodiment, the reversing path T5 is a path that runs from the transport roller pair 33 to the transport roller pair 31 via the transport roller pairs 35, 36, 37, and 38. The reversing path T5 passes above the line head 12 and is shaped to curve and invert the medium with the most recently recorded side facing outward. The reversing path T5 is a path that inverts the medium that has been switched back by the switchback path T4 and transports it again to the feeding path T1. The medium sent to the reversing path T5 enters the feeding path T1 upstream of the transport roller pair 31, and the line head 12 performs recording.

[0050] The reference numeral 10 denotes an ink storage unit serving as a liquid storage unit that stores ink before ejection. The ink to be ejected from the line head 12 is supplied from the ink storage unit 10 to the line head 12 via a tube (not shown). The ink storage unit 10 stores, as an example, black, yellow, magenta, and cyan inks.

[0051] The above is the overall configuration of the printer 1, and below we will explain an example of a mechanism that transmits power from the motor to the roller. A first frame 52 (see FIGS. 2 to 4) constitutes a part of the base of the housing 2. The first frame 52 is provided with a motor for driving each roller, and a power transmission mechanism such as gears and pulleys for transmitting power from the motor to each roller. As an example, Figures 2 and 3 show a first motor 103 that drives the transport roller pair 44 and a second motor 104 that drives the transport roller pair 43, as well as part of the mechanism that transmits power from these motors to each roller pair.

[0052] The first motor 103 and the second motor 104 are attached to a motor fixing frame 101. The motor fixing frame 101 has a first plate portion 101a, which is a portion for fixing the first motor 103 and the second motor 104, and which forms a surface parallel to the first frame 52, a second plate portion 101b, which is a portion perpendicular to the first plate portion 101a, and a third plate portion 101c, which forms a surface parallel to the first frame 52. The first plate portion 101a is connected to one end of the second plate portion 101b, and the third plate portion 101c is connected to the other end.

[0053] 3 shows a drive pulley 105 provided on the drive shaft of the first motor 103, a driven pulley 106, and an endless belt 107 wound around the drive pulley 105 and the driven pulley 106. Although detailed illustrations and explanations are omitted, the driven pulley 106 transmits power to the conveying roller pair 44. The third plate portion 101c is fixed to the first frame 52 by a fixing screw 111. Although one fixing screw 111 is shown in FIG. 3, the third plate portion 101c is actually fixed to the first frame 52 by two fixing screws 111 spaced apart in the Z-axis direction.

[0054] A hole 101d is formed in the first plate portion 101a, and a tubular member 102 is inserted into the hole 101d. The tubular member 102 has a flange portion 102b and a hollow portion 102a. A fixing screw 110 can be inserted into the hollow portion 102a, and the tubular member 102 can be fixed to the first frame 52 by the fixing screw 110. The first plate portion 101a is positioned relative to the first frame 52 via the flange portion 102b of the tubular member 102. By using a structure in which the motor fixing frame 101 is fixed to the first frame 52 via the cylindrical member 102 in this way, it is possible to fix the motor fixing frame 101 even in cases where it is not possible to ensure space for providing a screw fixing portion such as the third plate portion 101c. In addition, because the fixing screws 110 fit into the hollow portions 102a of the cylindrical member 102, it is possible to prevent the fixing screws 110 from falling between the first plate portion 101a and the first frame 52, improving the workability when attaching or detaching the motor fixing frame 101.

[0055] Next, the power transmission device 50 will be described in detail with reference to FIG. 4 and subsequent figures. The power transmission device 50 is a device that transmits the power of a motor (not shown) from the second gear 60 to the first gear 57, and further to the first rotating shaft 58. The power transmitted to the first rotating shaft 58 is transmitted to the pick roller 21 (see FIG. 1). The feed roller to which power is transmitted by the power transmission device 50 is not limited to the pick roller 21, but may be any other pair of transport rollers.

[0056] More specifically, in FIG. 4 , the power transmission device 50 has a first frame 52 that forms a surface parallel to the XZ plane. A bearing hole 52a is formed in the first frame 52, and a bearing portion 73 is held in the bearing hole 52a. The bearing portion 73 is an example of a second support portion and supports the second rotating shaft 61. In this embodiment, the bearing portion 73 is a rolling bearing, but it may also be a plain bearing. The inner diameter of the bearing hole 52a is sufficiently larger than the outer diameter of the bearing portion 73. That is, there is play between the inner circumferential surface of the bearing hole 52a and the outer circumferential surface of the bearing portion 73. This allows the second rotating shaft 61, supported by the bearing portion 73, to move with the bearing portion 73 as a fulcrum such that the axis of the shaft is tilted. Furthermore, this configuration allows the second rotating shaft 61 to move with the bearing portion 73 as a fulcrum, at low cost.

[0057] The second rotation shaft 61 is disposed so as to penetrate the first frame 52 along the Y-axis direction, and a fourth gear 66 is provided on the second rotation shaft 61 in the +Y direction relative to the first frame 52. As shown in FIG. 11 , a third gear 64 is provided below the fourth gear 66, and the fourth gear 66 and the third gear 64 mesh with each other. The third gear 64 is provided on a third rotation shaft 63, and the third rotation shaft 63 rotates by receiving power from a motor (not shown). Therefore, power from the motor (not shown) is transmitted from the third gear 64 to the fourth gear 66, thereby rotating the second rotation shaft 61.

[0058] Returning to FIG. 4 , a second gear 60 is provided at the end of the second rotating shaft 61 in the −Y direction. A second flange portion 71 is integrally provided with the second gear 60. The second gear 60 meshes with the first gear 57 and transmits power to the first gear 57. In this embodiment, the first gear 57 is provided integrally with a housing 70a of the electromagnetic clutch 70. The electromagnetic clutch 70 switches between a state in which power is transmitted to the first rotary shaft 58 and a state in which power is not transmitted to the first rotary shaft 58 under the control of a control unit (not shown).

[0059] A frame assembly made up of a second frame 53, a third frame 54, a fourth frame 55, and a fifth frame 56 is provided in the -Y direction relative to the first frame 52, and the electromagnetic clutch 70 is supported by the fourth frame 55. The second frame 53 is attached to the first frame 52. The third frame 54 is attached to the second frame 53. The fourth frame 55 is attached to the third frame 54. Since the electromagnetic clutch 70 is supported by the fourth frame 55, the dimensional tolerances of the first frame 52, the second frame 53, the third frame 54, and the fourth frame 55 are present between the first gear 57 and the second gear 60. At least a portion of the first rotating shaft 58 in the axial direction is supported by the electromagnetic clutch 70. Therefore, the electromagnetic clutch 70 is an example of a first support portion that supports the first rotating shaft 58 in a fixed manner.

[0060] As described above, the second rotating shaft 61 can move so that the shaft center line tilts around the bearing portion 73. In this embodiment, the second rotating shaft 61 can move so that the second gear 60 moves forward and backward relative to the first gear 57. A flanged bearing 74 is provided on the second rotating shaft 61 between the bearing portion 73 and the second gear 60. The flanged bearing 74 is held by two E-rings 75 so as not to move in the axial direction of the second rotating shaft 61.

[0061] The flanged bearing 74 has flange portions 74a and 74b. A large diameter portion 76 is provided between the flange portions 74a and 74b, so that two small diameter portions are provided along the axial direction between the flange portions 74a and 74b. A guide plate 78 is inserted into the small diameter portion between the large diameter portion 76 and the flange portion 74a. The guide plate 78 is open in the -X direction, and the inside of the opening extends along the X axis direction, thereby guiding the second rotating shaft 61 in the X axis direction. This allows the second rotating shaft 61 to swing in the XY plane with the bearing portion 73 as a fulcrum.

[0062] One end 77a of a torsion coil spring 77, which is an example of a pressing member, is inserted into the small diameter portion between the large diameter portion 76 and the flange portion 74b. The one end 77a presses the flanged bearing 74 in the −X direction, that is, presses the second rotating shaft 61 in the −X direction. By pressing the torsion coil spring 77 against the second rotating shaft 61 via the flanged bearing 74, it is possible to avoid the generation of frictional resistance that would otherwise accompany sliding between the rotating second rotating shaft 61 and the torsion coil spring 77.

[0063] In FIG. 6, the straight line indicated by the symbol Lk1 is the axial center line of the first rotating shaft 58, and the straight line indicated by the symbol Lk2 is the axial center line of the second rotating shaft 61. In this embodiment, the axial center line Lk1 is parallel to the Y-axis direction. Furthermore, in this embodiment, when the second gear 60 is meshed with the first gear 57, the axial center line Lk2 is inclined with respect to the Y-axis direction. That is, in this embodiment, the axial center line Lk1 and the axial center line Lk2 are not parallel. However, when the second gear 60 is meshed with the first gear 57, the axial center line Lk2 may be parallel to the Y-axis direction, that is, the axial center line Lk1 and the axial center line Lk2 may be parallel.

[0064] The portion of the second rotating shaft 61 on the −Y side of the bearing 73 is pressed in the −X direction by the torsion coil spring 77, i.e., toward the first rotating shaft 58. As a result, a force acts on the second gear 60 in the −X direction, i.e., in the direction toward the first gear 57.

[0065] As described above, the bearing portion 73 serving as the second support portion supporting the second rotating shaft 61 in the power transmission device 50 has play between it and the bearing hole 52a, thereby allowing movement of the second rotating shaft 61 in the direction in which the second gear 60 advances and retreats relative to the first gear 57, and a force acts on the second gear 60 in a direction toward the first gear 57. This allows a space-saving configuration for moving the second gear 60 back and forth relative to the first gear 57, and prevents the device from becoming larger. This also allows proper meshing between the first gear 57 and the second gear 60, thereby achieving proper power transmission.

[0066] The power transmission device 50 also includes a torsion coil spring 77, which is a pressing member that presses the second rotating shaft 61 toward the first rotating shaft 58, and is configured such that a force toward the first gear 57 acts on the second gear 60 when the second rotating shaft 61 is pressed by the torsion coil spring 77. This allows the first gear 57 and the second gear 60 to maintain appropriate meshing. The pressing member may be configured to pull the second rotating shaft 61 toward the first rotating shaft 58.

[0067] The direction in which the second gear 60 moves forward and backward relative to the first gear 57, in other words, the direction in which the second gear 60 presses against the first gear 57, will be further described below. First, the force acting on the meshing portion between the second gear 60 and the first gear 57 will be described with reference to FIG. Here, the symbols shown in Figure 7 will be explained. Point C1 is the center of the first rotation shaft 58, hereinafter referred to as the first axis center C1. Point C2 is the center of the second rotation shaft 61, hereinafter referred to as the second axis center C2. Line L1 is a line that passes through the first axis center C1 and the second axis center C2.

[0068] Point Tp is the pitch point where the teeth of first gear 57 and second gear 60 come into contact. Symbol L2 is the common tangent to the tooth flanks at pitch point Tp, and symbol L3 is the common normal to the tooth flanks at pitch point Tp. Symbol α is the pressure angle, typically set to 20°, but may be any other angle. Symbol E1a is the reference circle of the first gear 57 that passes through the pitch point Tp, symbol E1b is the root circle of the first gear 57, and symbol E1c is the tip circle of the first gear 57. Symbol E2a is the reference circle of the second gear 60 that passes through the pitch point Tp, symbol E2b is the root circle of the second gear 60, and symbol E2c is the tip circle of the second gear 60. Symbol Fg is a force acting on second gear 60 in the -X direction, i.e., toward first gear 57. Symbol M is the angle between first straight line L1 and the acting direction of force Fg. Symbol B is the angle between reaction force Fr (described later) and the acting direction of force Fg. The straight line L5 is a line that passes through the first axis center C1 and is parallel to the direction in which the force Fg acts, in other words, the direction in which the second gear 60 advances toward the first gear 57.

[0069] The second gear 60 rotates in a rotational direction R1 and transmits power to the first gear 57. The first gear 57 receives power from the second gear 60 and rotates in a rotational direction R2. In this case, the second gear 60 receives a reaction force Fr from the first gear 57 at the pitch point Tp. The direction of action of the reaction force Fr is parallel to the common normal line L3. Symbol f1 is a component of the reaction force Fr, which is parallel to the X-axis direction, i.e., the direction in which the second gear 60 advances or retreats relative to the first gear 57. Symbol f2 is a component of the reaction force Fr, which is a component in a direction perpendicular to the advance or retreat direction.

[0070] The direction in which the second gear 60 faces relative to the first gear 57 is determined by the angle M. Below, examples of the direction in which the second gear 60 faces relative to the first gear 57 will be described with reference to Figure 8 onwards. Note that in Figure 8 onwards, the gears are simply shown by using solid lines as reference lines. First, the angle M affects the direction of action and the magnitude of the component force f1. If the direction of action of the component force f1 is opposite to the direction of action of the force Fg and the magnitude of the component force f1 is large, the force of the second gear 60 toward the first gear 57 becomes small, and there is a risk that the meshing between the second gear 60 and the first gear 57 cannot be maintained properly. When the second rotation shaft 61 is pressed straight toward the first rotation shaft 58, that is, when the angle M is 0°, the component force f1 is larger than when the angle M is greater than 0°. In other words, when the angle M is 0°, the first straight line L1 and the acting direction of the force Fg, that is, the direction in which the second gear 60 advances, are parallel to each other. However, as shown in Figure 7, if the first line L1 and the advancing direction of the second gear 60 are not parallel and the second axis center C2 is positioned in the direction of the reaction force Fr from the second line L5, the angle M can be made larger than 0°. This causes the component force f1 to act in the advancing direction of the second gear 60, or even if it acts in the opposite direction to the advancing direction of the second gear 60, its magnitude becomes small. This makes it possible to maintain appropriate meshing between the first gear 57 and the second gear 60.

[0071] A more detailed explanation is given below. In Fig. 8, the angle M is larger than the pressure angle α but smaller than 90°, and the angle B formed by the reaction force Fr and the acting direction of the force Fg is an acute angle. As a result, the component force f1 of the reaction force Fr that the second gear 60 receives from the first gear 57 acts in a direction in which the second gear 60 advances toward the first gear 57. This makes it possible to maintain appropriate meshing between the first gear 57 and the second gear 60.

[0072] 8 is a configuration in which, when viewed from the axial direction of the first rotation shaft 58, the first straight line L1 and the direction in which the second gear 60 advances and retreats are non-parallel, and the component force f1 of the reaction force Fr acts in a direction in which the second gear 60 advances toward the first gear 57. This makes it possible to appropriately maintain meshing between the first gear 57 and the second gear 60, compared to a case in which the component force f1 acts in a direction in which the second gear 60 retreats from the first gear 57.

[0073] Next, FIG. 9 shows an embodiment in which the angle M is equal to the pressure angle α. With this configuration, the reaction force Fr is perpendicular to the direction of advance and retreat of the second gear 60. That is, the angle B is 90°. This prevents the reaction force Fr from adversely affecting the force Fg in the direction in which the second gear 60 moves toward the first gear 57.

[0074] Next, FIG. 10 shows a configuration in which a force Fg acts on the second gear 60 in a direction toward the first gear 57 due to the weight of the second rotating shaft 61 and the weight of the second gear 60 itself. With this configuration, there is no need for a dedicated component for generating force Fg, such as a spring, or even if a spring is used, only a small spring force is required, allowing for a smaller device and lower costs. In FIG. 10, only the weight of the second rotating shaft 61 and the weight of the second gear 60 act on the second gear 60, and no spring force acts on it, but it may be configured so that a spring force acts on it.

[0075] Next, other characteristic configurations of the power transmission device 50 according to this embodiment will be described. The power transmission device 50 has a housing 70a as a first flange portion that is coaxial with the first gear 57. Note that "coaxial" means that they share a common rotation axis. In this embodiment, the outer peripheral surface of the housing 70a is a smooth surface without any irregularities. Furthermore, the outer peripheral surface of the housing 70a does not protrude radially outward beyond the addendum circle E1c of the first gear 57 (see FIG. 7). The power transmission device 50 also has a second flange portion 71 that is coaxial with the second gear 60. In this embodiment, the outer peripheral surface of the second flange portion 71 is a smooth surface without any irregularities. Furthermore, the outer peripheral surface of the second flange portion 71 does not protrude radially outward beyond the addendum circle E2c of the second gear 60 (see FIG. 7).

[0076] The sum of the diameter of the housing 70a and the diameter of the second flange portion 71 is smaller than the sum of the diameter of the tip circle E1c (see Figure 7) of the first gear 57 and the diameter of the tip circle E2c (see Figure 7) of the second gear 60, and is greater than the sum of the diameter of the root circle E1b (see Figure 7) of the first gear 57 and the diameter of the root circle E2b (see Figure 7) of the second gear 60. Then, a force Fg (see FIG. 7) acting on the second gear 60 in a direction toward the first gear 57 causes the second flange portion 71 to come into contact with the housing 70a as shown in FIGS. This allows the inter-axial distance between the first rotating shaft 58 and the second rotating shaft 61 to be appropriately maintained, allowing the first gear 57 and the second gear 60 to mesh appropriately. In particular, even if the force Fg acting on the second gear 60 in the direction toward the first gear 57 is large, the first gear 57 and the second gear 60 can mesh appropriately. The first flange portion may be integral with the first gear 57, similar to the second flange portion 71.

[0077] In this embodiment, the housing 70a of the electromagnetic clutch 70 also serves as a first flange portion coaxial with the first gear 57. This eliminates the need to provide the first flange portion as a dedicated member, allowing for miniaturization and cost reduction of the device. Furthermore, instead of the electromagnetic clutch 70 being configured to switch on and off the power transmission between the first gear 57 and the first rotating shaft 58, it may be configured to switch on and off the power transmission between the second rotating shaft 61 and the second gear 60. Furthermore, the first flange portion coaxial with the first gear 57 may be rotatable relative to the first gear 57 and the first rotating shaft 58. Similarly, the second flange portion coaxial with the second gear 60 may be rotatable relative to the second gear 60 and the second rotating shaft 61. In addition, instead of a configuration in which the axial distance between the first gear 57 and the second gear 60 is regulated by the abutment of the two flange portions, a configuration in which a member that abuts against the second rotating shaft 61 is provided to regulate the advancement of the second rotating shaft 61 toward the first rotating shaft 58 and thereby regulate the axial distance between the first gear 57 and the second gear 60 may be adopted.

[0078] In this embodiment, as explained with reference to Fig. 4, by providing play between the inner peripheral surface of the bearing hole 52a and the outer peripheral surface of the bearing portion 73, the second rotating shaft 61 can move so that the shaft center line tilts with the bearing portion 73 as a fulcrum, but instead of this configuration, an aligning bearing may be used for the bearing portion 73. This makes it easy to obtain a configuration that allows movement of the second rotating shaft 61. When an aligning bearing is used for the bearing portion 73, it is not necessary to provide play between the inner peripheral surface of the bearing hole 52a and the outer peripheral surface of the bearing portion 73. Also, by providing a play between the bearing portion 73 and the second rotating shaft 61, the second rotating shaft 61 may be configured to tilt with the bearing portion 73 as a fulcrum.

[0079] Next, the arrangement of the fourth gear 66 relative to the third gear 64 will be described with reference to FIG. 11, the line L4 is a line that passes through the second axis center C2 of the second rotation shaft 61 and the third axis center C3 of the third rotation shaft 63. In addition, in Fig. 11, the direction of advance and retreat of the second gear 60 is along the X-axis direction, and the fourth gear 66 moves in the +X direction as the second rotation shaft 61 moves in the -X direction. The angle Q is the angle between the direction in which the fourth gear 66 moves and the line L4. In this embodiment, the angle Q is 90°, that is, the direction of advancement and retreat of the second gear 60, in other words, the direction of displacement of the fourth gear 66, is along a direction perpendicular to the straight line L4. This provides the following effects.

[0080] When the second rotating shaft 61 moves so that the second gear 60 moves back and forth relative to the first gear 57, the fourth gear 66 provided on the second rotating shaft 61 also displaces, which may result in improper meshing between the third gear 64 and the fourth gear 66. However, according to this embodiment, the forward and backward movement direction of the second gear 60, in other words, the displacement direction of the fourth gear 66, is along a direction perpendicular to the straight line L4. Therefore, even if the second rotating shaft 61 moves, the change in the axial distance between the third rotating shaft 63 and the second rotating shaft 61 can be suppressed, and improper meshing between the third gear 64 and the fourth gear 66 can be suppressed. The advancing / retreating direction of the second gear 60, in other words, the displacement direction of the fourth gear 66, being along a direction perpendicular to the straight line L4 does not necessarily mean that the angle Q is strictly 90°, but rather includes a certain range, and as an example, the angle Q can be set appropriately within the range of 90±20°.

[0081] 6, the bearing 73 is located between the second gear 60 and the fourth gear 66 in the axial direction of the second rotating shaft 61. The distance d1 between the fourth gear 66 and the bearing 73 is shorter than the distance d2 between the second gear 60 and the bearing 73. This makes it possible to suppress the displacement of the fourth gear 66 compared to the displacement of the second gear 60 when the second rotating shaft 61 moves around the bearing 73 as a fulcrum. This makes it possible to suppress improper meshing between the third gear 64 (see FIG. 11) and the fourth gear 66.

[0082] The present invention is not limited to the embodiments and modifications described above, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these modifications are also included in the scope of the present invention. For example, angle M may be set smaller than pressure angle α. In this case, the acting direction of component force f1 of reaction force Fr is opposite to the acting direction of force Fg, but it is sufficient if force Fg is sufficiently larger than component force f1. [Explanation of symbols]

[0083] 1...inkjet printer, 2...casing, 3...media cassette, 5...media transport device, 8...output tray, 10...ink storage section, 12...line head, 13...nozzle, 16...belt unit, 17...transport belt, 18...first roller, 19...second roller, 21...pick roller, 25...feed roller pair, 29-44...transport roller pairs, 49...shaft support section, 50...power transmission device, 52...first frame, 52a...bearing hole, 53...second frame, 54...third frame, 55...fourth frame, 56...fifth frame, 57...first gear, 58...first rotating shaft, 59...bearing section, 60...second gear, 61...second rotating shaft, 63...third rotating shaft, 64...third gear, 66...fourth gear, 70...electromagnetic clutch, 70a...casing, 71...second flange portion, 73...bearing portion, 74...flanged bearing, 75...E-ring, 76...large diameter portion, 77...torsion coil spring, 78...guide plate, 101...motor fixing frame, 101a...first plate portion, 101b...second plate portion, 101c...third plate portion, 102...cylindrical member, 102a...hollow portion, 102b... flange portion, 103... first motor, 104... second motor, 105... driving pulley, 106... driven pulley, 107... endless belt, 110, 111... fixing screws, T1... feeding path, T2... conveying path, T3... guide path, T4... switchback path, T5... reversing path, T6... discharge path

Claims

1. a first gear provided on the first rotation shaft; a second gear provided on a second rotation shaft and meshing with the first gear; a first support portion that supports the first rotation shaft; a second support portion that supports the second rotation shaft; and the second support portion allows movement of the second rotation shaft in a direction in which the second gear advances and retreats relative to the first gear, A force acts on the second gear in a direction toward the first gear. A power transmission device characterized by:

2. 2. The power transmission device according to claim 1, a pressing member that presses the second rotation shaft toward the first rotation shaft, When the second rotation shaft is pressed by the pressing member, a force acts on the second gear in a direction toward the first gear. A power transmission device characterized by:

3. 2. The power transmission device according to claim 1, a force acting on the second gear in a direction toward the first gear due to the weight of the second rotation shaft and the weight of the second gear; A power transmission device characterized by:

4. 2. The power transmission device according to claim 1, a first line passing through a first axis center of the first rotation shaft and a second axis center of the second rotation shaft is non-parallel to an advancing direction of the second gear toward the first gear, as viewed in an axial direction of the first rotation shaft; a second line is a line passing through the first shaft center and parallel to the advance direction, and the second shaft center is located in a direction of a reaction force that the second gear receives from the first gear relative to the second line; A power transmission device characterized by:

5. 5. The power transmission device according to claim 4, a first line passing through a first axis center of the first rotation shaft and a second axis center of the second rotation shaft is non-parallel to a direction in which the second gear advances and retreats, as viewed from an axial direction of the first rotation shaft; a component of the reaction force that the second gear receives from the first gear acts in a direction in which the second gear advances toward the first gear; A power transmission device characterized by:

6. 5. The power transmission device according to claim 4, an angle formed by a first line passing through a first axis center of the first rotation shaft and a second axis center of the second rotation shaft and a direction of advancement and retreat of the second gear when viewed in the axial direction of the first rotation shaft is greater than a pressure angle of the second gear and smaller than 90°; an angle formed by a reaction force that the second gear receives from the first gear and a direction in which the second gear advances toward the first gear is an acute angle; A power transmission device characterized by:

7. 5. The power transmission device according to claim 4, an angle formed by a first line passing through a first axis center of the first rotation shaft and a second axis center of the second rotation shaft and a direction of advancement and retreat of the second gear when viewed from the axial direction of the first rotation shaft is equal to a pressure angle of the second gear; A power transmission device characterized by:

8. 2. The power transmission device according to claim 1, the first gear has a first flange portion coaxial with the first gear, the second gear has a second flange portion coaxial with the second gear, a sum of a diameter of the first flange portion and a diameter of the second flange portion is smaller than a sum of a diameter of an addendum circle of the first gear and a diameter of an addendum circle of the second gear, and is larger than a sum of a diameter of a root circle of the first gear and a diameter of a root circle of the second gear, a force acting on the second gear in a direction toward the first gear causes the second flange portion to abut against the first flange portion; A power transmission device characterized by:

9. 9. The power transmission device according to claim 8, a clutch that switches between connection and disconnection of power transmission between the first gear and the first rotating shaft, The clutch housing also serves as the first flange portion. A power transmission device characterized by:

10. 2. The power transmission device according to claim 1, The second support portion is constituted by an aligning bearing. A power transmission device characterized by:

11. 2. The power transmission device according to claim 1, the second support portion is a bearing portion that receives the second rotation shaft and includes a bearing portion that is supported by a frame, The bearing portion has a play between itself and the frame, thereby allowing movement of the second rotation shaft in a direction in which the second gear advances and retreats relative to the first gear. A power transmission device characterized by:

12. The power transmission device according to any one of claims 1 to 11, a third gear provided on the third rotation shaft; a fourth gear that is a gear provided on the second rotation shaft at an axial distance from the second gear and that meshes with the third gear; Further provided with When viewed from the axial direction of the third rotation shaft, the advancing and retreating direction of the second gear is along a direction perpendicular to a line passing through an axial center of the second rotation shaft and an axial center of the third rotation shaft. A power transmission device characterized by:

13. The power transmission device according to any one of claims 1 to 11, a third gear provided on the third rotation shaft; a fourth gear that is a gear provided on the second rotation shaft at an axial distance from the second gear and that meshes with the third gear; Further provided with the second support portion is located between the second gear and the fourth gear in the axial direction of the second rotation shaft, a distance between the fourth gear and the second support portion is shorter than a distance between the second gear and the second support portion; A power transmission device characterized by:

14. The power transmission device according to claim 1; a feed roller that receives power from the second gear via the first gear and rotates to feed the medium; A medium transport device comprising:

15. 15. The medium transport device according to claim 14, a medium support unit that supports the medium before feeding; The feed roller feeds the medium from the medium support section. A medium transport device characterized by:

16. a medium transport device according to claim 14 or 15; a recording unit that records on the medium transported by the medium transport device; A recording device comprising:

Images