Drive transmission device, medium conveyance device, recording device

Abstract

To avoid a risk that when a flange is arranged at a pulley in order to prevent detachment of an endless belt from the pulley, the endless belt makes strong contact with the flange in response to movement of the endless belt in an axial direction, which can lead to a fracture of the endless belt.SOLUTION: A drive transmission device comprises: three or more pulleys; and an endless belt bridged over the plurality of pulleys, the endless belt having multiple linear belt sections each formed between two of the pulleys. A first flange is arranged on a first pulley, the first pulley being the pulley that forms the longest belt section and does not form the shortest belt section out of the plurality of belt sections. An interval between the first flange and a side face of the endless belt is further smaller than the smallest interval among intervals formed between flanges provided respective ones of the other pulleys and the side face of the endless belt.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a drive transmission device that transmits the power of a drive source to an endless belt. The present invention also relates to a medium conveyance device including the drive transmission device. Furthermore, the present invention relates to a recording device including the medium conveyance device or the drive transmission device.

Background Art

[0002] A drive transmission device that drives an endless belt spanned between at least two pulleys is used in various devices, including office equipment typified by facsimiles and printers. Patent Document 1 discloses an image forming apparatus, which is an example of such a device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since tension is applied to the endless belt to suppress slack, the rotation axis of the pulley may be deformed in any of the plurality of pulleys over which the endless belt is spanned, and the endless belt may move in the axial direction under the influence. Here, if a flange is provided on the pulley to prevent the endless belt from coming off the pulley, as the endless belt moves in the axial direction, the endless belt strongly contacts the flange, resulting in stress concentration and possibly causing the endless belt to break. However, if the flange is not provided, there is a risk that the endless belt will come off the pulley.

Means for Solving the Problems

[0005] To solve the above problems, the drive transmission device of the present invention includes a plurality of three or more pulleys and an endless belt spanned over the plurality of pulleys, the endless belt having a plurality of linear belt sections formed between two of the pulleys. Among the plurality of belt sections, a first pulley that forms the longest belt section and does not form the shortest belt section is provided with a first flange, and the first flange restricts the movement of the endless belt in the axial direction of the pulley when the endless belt rotates.

[0006] Further, the drive transmission device of the present invention includes a plurality of three or more pulleys and an endless belt spanned over the plurality of pulleys, the endless belt having a plurality of linear belt sections formed between two of the pulleys. Among the plurality of belt sections, a first pulley that forms the longest belt section and does not form the shortest belt section is provided with a first flange, and the distance between the first flange and the side surface of the endless belt is smaller than the smallest distance among the distances between the flanges provided on the other pulleys and the side surface of the endless belt.

[0007] Further, the medium conveyance device of the present invention includes any one of the above drive transmission devices and at least one roller for conveying a medium, the at least one roller being driven by any one of the above drive transmission devices. Further, the recording device of the present invention includes a recording unit for recording on a medium, any one of the above drive transmission devices, and at least one roller for conveying a medium, the at least one roller being driven by any one of the above drive transmission devices.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009] The present invention will be schematically described below. The drive transmission device according to the first aspect includes a plurality of three or more pulleys and an endless belt spanned over the plurality of pulleys, the endless belt having a plurality of linear belt sections formed between two of the pulleys. Among the plurality of belt sections, a first pulley that forms the longest belt section and does not form the shortest belt section is provided with a first flange, and the distance between the first flange and the side surface of the endless belt is smaller than the smallest distance among the distances between the flanges provided on the other pulleys and the side surface of the endless belt.

[0010] In the endless belt, the shorter the length of the belt section, the stronger the endless belt contacts the flange provided on the pulley forming the belt section, and the easier the endless belt is to break. However, according to this aspect, the first flange with the smallest distance from the side surface of the endless belt, that is, the first flange that restricts the axial movement of the endless belt when the endless belt rotates, is provided on the first pulley that forms the longest belt section and does not form the shortest belt section among the plurality of belt sections. Therefore, the force with which the endless belt contacts the first flange can be suppressed, thereby suppressing the breakage of the endless belt while restricting the axial movement of the endless belt. Note that the first flange restricting the movement of the endless belt means that the first flange contributes most to restricting the movement of the endless belt, and it means that other flanges may be in contact with the endless belt.

[0011] Moreover, the drive transmission device according to the second aspect includes a plurality of three or more pulleys and an endless belt spanned over the plurality of pulleys, wherein a plurality of linear belt sections formed between two of the pulleys are formed, and among the plurality of belt sections, a first pulley that forms the longest belt section and does not form the shortest belt section is provided with a first flange, and the first flange restricts the movement of the endless belt in the axial direction of the pulley when the endless belt rotates.

[0012] In the endless belt, the shorter the length of the belt section, the stronger the endless belt contacts the flange provided on the pulley forming the belt section, and the more likely the endless belt is to break. However, according to this aspect, since the first flange that restricts the movement of the endless belt in the axial direction when the endless belt rotates is provided on the first pulley that forms the longest belt section and does not form the shortest belt section among the plurality of belt sections, the force with which the endless belt contacts the first flange can be suppressed, thereby suppressing the breakage of the endless belt while restricting the movement of the endless belt in the axial direction.

[0013] The third aspect is characterized in that, in the first or second aspect, the first pulley forms the longest belt section and the second longest belt section among the plurality of belt sections. According to this aspect, since the first pulley forms the longest belt section and the second longest belt section among the plurality of belt sections, the force with which the endless belt contacts the first flange can be further suppressed, and thus the breakage of the endless belt can be more reliably suppressed.

[0014] The fourth aspect is characterized in that, in any one of the first to third aspects, the outer diameter of the first pulley is larger than the minimum outer diameter among the plurality of pulleys. The smaller the outer diameter of the pulley, the smaller the area where stress occurs in the endless belt when the endless belt contacts the first flange, that is, stress concentration is likely to occur and the endless belt is likely to break. However, according to this aspect, since the outer diameter of the first pulley is larger than the minimum outer diameter among the plurality of pulleys, the breakage of the endless belt due to the above-mentioned stress concentration can be suppressed.

[0015] A fifth aspect is characterized in that, in the fourth aspect, the outer diameter of the first pulley is the maximum outer diameter among the plurality of pulleys. According to this aspect, since the outer diameter of the first pulley is the maximum outer diameter among the plurality of pulleys, the breakage of the endless belt due to the above-mentioned stress concentration can be more reliably suppressed.

[0016] A sixth aspect is, in the first to fifth aspects, a pulley constituting the plurality of pulleys, a second pulley that forms the longest belt section together with the first pulley, a rotation axis of the first pulley, a first rotation axis provided with the first pulley at an axial end, a rotation axis of the second pulley, a second rotation axis provided with the second pulley at an axial end, a first bearing portion for receiving the first rotation axis, and a second bearing portion for receiving the second rotation axis, and at least one of the axial end of the first rotation axis provided with the first pulley with respect to the first bearing portion and the axial end of the second rotation axis provided with the second pulley with respect to the second bearing portion is a free end.

[0017] At least one of the shaft end portions of the first rotating shaft provided with the first pulley and the shaft end portions of the second rotating shaft provided with the second pulley is a free end, having a so-called cantilever beam structure, and at least one of the first rotating shaft and the second rotating shaft is easily bent toward the inside of the endless belt by the tension of the endless belt. When at least one of the first rotating shaft and the second rotating shaft bends in this way, the pulley provided on the bent rotating shaft inclines toward the inside of the endless belt, and the endless belt moves in the axial direction. And due to such movement of the endless belt, the endless belt strongly contacts the flange provided on the pulley and the breakage of the endless belt is likely to occur. However, according to the first or second aspect described above, while suppressing the breakage of the endless belt, the movement of the endless belt in the axial direction can be restricted.

[0018] A seventh aspect is characterized in that, in the sixth aspect, both the shaft end portion of the first rotating shaft provided with the first pulley with respect to the first bearing portion and the shaft end portion of the second rotating shaft provided with the second pulley with respect to the second bearing portion are free ends. According to this aspect, both the first rotating shaft and the second rotating shaft have a cantilever beam structure and are easily bent toward the inside of the endless belt. Therefore, both the first pulley and the second pulley incline toward the inside of the endless belt, and the endless belt is more likely to move in the axial direction, and the breakage of the endless belt described above is more likely to occur. However, according to the first or second aspect described above, while suppressing the breakage of the endless belt, the movement of the endless belt in the axial direction can be restricted.

[0019] The eighth aspect is that, in the sixth or seventh aspect, the plurality of pulleys include a third pulley that applies tension to the endless belt and is adjacent to the second pulley, and a fourth pulley that is provided on the drive shaft of the motor and is adjacent to the third pulley and the first pulley. The length of the belt section increases in the following order: the belt section between the third pulley and the fourth pulley, the belt section between the second pulley and the third pulley, the belt section between the first pulley and the fourth pulley, and the belt section between the first pulley and the second pulley. The outer diameters of the first pulley and the second pulley are larger than the outer diameter of the third pulley, the outer diameter of the third pulley is larger than the outer diameter of the fourth pulley. The second pulley is provided with a second flange facing the side surface of the endless belt, and the third pulley is provided with a third flange facing the side surface of the endless belt. The distance between the first flange and the side surface of the endless belt and the distance between the second flange and the side surface of the endless belt are both smaller than the distance between the third flange and the side surface of the endless belt.

[0020] According to this aspect, since the first pulley and the second pulley form the longest belt section, and the distance between the first flange and the side surface of the endless belt and the distance between the second flange and the side surface of the endless belt are both smaller than the distance between the third flange and the side surface of the endless belt, the force with which the endless belt contacts the first flange and the force with which the endless belt contacts the second flange can be suppressed, the breakage of the endless belt at each flange can be suppressed, and the axial movement of the endless belt can be restricted. In addition, in this specification, two pulleys being adjacent means that, regardless of the distance between the two pulleys, the two pulleys form a linear belt section.

[0021] The drive transmission device according to the ninth aspect includes a drive pulley driven by a drive source, a plurality of driven pulleys, and an endless belt spanned over the drive pulley and the plurality of driven pulleys. The plurality of driven pulleys includes a first pulley, a second pulley adjacent to the first pulley, and a third pulley adjacent to the second pulley. The first rotation shaft, which is the rotation shaft of the first pulley and has the first pulley provided at an axial end portion thereof, the second rotation shaft, which is the rotation shaft of the second pulley and has the second pulley provided at an axial end portion thereof, a first bearing portion for receiving the first rotation shaft, and a second bearing portion for receiving the second rotation shaft are provided. With respect to the first bearing portion, the axial end portion of the first rotation shaft on which the first pulley is provided is a free end. With respect to the second bearing portion, the axial end portion of the second rotation shaft on which the second pulley is provided is a free end. The first pulley has a first flange facing the side surface of the endless belt, the second pulley has a second flange facing the side surface of the endless belt, and the third pulley has a third flange facing the side surface of the endless belt. The third pulley is provided so as to be axially displaceable, and when the endless belt rotates, the force with which the endless belt contacts the third flange is smaller than the force with which the endless belt contacts the first flange and the force with which the endless belt contacts the second flange.

[0022] The shaft end of the first rotating shaft provided with the first pulley is a free end, and the shaft end of the second rotating shaft provided with the second pulley is also a free end. Therefore, both have a so-called cantilever beam structure. Both the first rotating shaft and the second rotating shaft are easily deflected toward the inside of the endless belt due to the tension of the endless belt. When the first rotating shaft and the second rotating shaft are deflected in this way, the first pulley and the second pulley tilt toward the inside of the endless belt, and the endless belt moves in the axial direction. Then, due to such movement of the endless belt, the endless belt strongly contacts the flange provided on the third pulley, and the endless belt is likely to break. However, the third pulley is axially displaceable. As a result, when the endless belt rotates, the force with which the endless belt contacts the third flange is smaller than the force with which the endless belt contacts the first flange and the second flange. Therefore, breakage of the endless belt can be suppressed.

[0023] The drive transmission device according to the tenth aspect includes a plurality of three or more pulleys and an endless belt spanned over the plurality of pulleys, the endless belt having a plurality of linear belt sections formed between two of the pulleys. Among the plurality of belt sections, the pulley that forms the shortest belt section and does not form the longest belt section is provided as a displacement pulley so as to be axially displaceable. Due to the displacement of the displacement pulley, when the endless belt rotates, the force with which the endless belt contacts the flange provided on the displacement pulley is smaller than the force with which the endless belt contacts the flanges provided on other pulleys.

[0024] In the endless belt, the shorter the length of the belt section, the stronger the endless belt contacts the flange provided on the pulley forming the belt section when the flange is provided on the pulley, and the more easily the endless belt breaks. However, according to the present aspect, among the plurality of belt sections, the pulley that forms the shortest belt section and does not form the longest belt section is provided as a displacement pulley so as to be axially displaceable. Due to the displacement of the displacement pulley, when the endless belt rotates, the force with which the endless belt contacts the flange provided on the displacement pulley becomes smaller than the force with which the endless belt contacts the flange provided on other pulleys. Therefore, breakage of the endless belt can be suppressed.

[0025] The medium conveyance device according to the eleventh aspect includes the drive transmission device according to any one of the first to tenth aspects, and at least one roller that conveys a medium and is driven by the drive transmission device. According to the present aspect, in the medium conveyance device, any of the operational effects of the above-described first to tenth aspects can be obtained.

[0026] The recording device according to the twelfth aspect includes a recording unit that performs recording on a medium, and the medium conveyance device according to the eleventh aspect. According to the present aspect, in the recording device, any of the operational effects of the above-described first to eleventh aspects can be obtained.

[0027] The recording device according to the thirteenth aspect includes a recording unit that performs recording on a medium, the drive transmission device according to any one of the sixth to ninth aspects, an upstream roller that is driven by the second pulley of the drive transmission device and is located upstream of the recording unit in the medium conveyance path, and a downstream roller that is driven by the first pulley of the drive transmission device and is located downstream of the recording unit in the medium conveyance path. According to the present aspect, in the recording device including the upstream roller driven by the second pulley of the drive transmission device and the downstream roller driven by the first pulley of the drive transmission device, any of the operational effects of the above-described sixth to eighth aspects can be obtained.

[0028] Hereinafter, the present invention will be specifically described. In each figure, the X-axis direction is the width direction of the apparatus, which is also the direction intersecting the medium conveyance direction, that is, the width direction of the medium. The Y-axis direction is the depth direction of the apparatus. The -Y direction is the direction from the front surface of the apparatus toward the back surface of the apparatus, and the +Y direction is the direction from the back surface of the apparatus toward the front surface of the apparatus. Further, the Z-axis direction is the vertical direction. The +Z direction is vertically upward, and the -Z direction is vertically downward.

[0029] In FIG. 1, an inkjet printer 1, which is an example of a recording apparatus, is a so-called multifunction device including a scanner unit 3 on the upper part of an apparatus main body 2. Hereinafter, the term "inkjet printer" will be abbreviated as "printer". The apparatus main body 2 has a function of performing recording on a medium typified by recording paper, and the scanner unit 3 has a function of reading a document.

[0030] The apparatus main body 2 detachably includes two medium storage cassettes 4A and 4B from the front of the apparatus. Further, the apparatus main body 2 is configured to be able to set and feed a medium from the upper part at the back of the apparatus. In FIG. 1, reference numeral 7 is a cover for opening and closing a medium set port (not shown) when setting a medium from the upper part at the back of the apparatus.

[0031] The apparatus main body 2 includes an operation unit 5 for performing various operations of the printer 1 on the front surface of the apparatus. The operation unit 5 includes a display unit and a plurality of operation buttons, and is provided so as to be tiltable. Below the operation unit 5, a discharge tray 6 for receiving a medium on which recording is performed and discharged is provided so as to be pullable out from the apparatus main body 2.

[0032] Subsequently, the medium conveyance path in the apparatus main body 2 will be described with reference to FIG. 2. In the printer 1, the medium is conveyed to a conveyance drive roller 16 via a reverse roller 21 that constitutes a reverse path RR regardless of the feed path. Then, the medium is conveyed by the conveyance drive roller 16 to a recording area by a recording head 9.

[0033] More specifically, the printer 1 includes a medium feed path K1 for feeding a medium from the medium storage cassette 4A as a medium feed path, a medium feed path K2 for feeding a medium from a medium storage cassette 4B (not shown in FIG. 2) below the medium storage cassette 4A, and a medium feed path K3 for feeding a medium manually from the upper rear of the apparatus.

[0034] The printer 1 also includes, as a medium conveyance path, a first medium conveyance path FR1, a reversal path RR, a second medium conveyance path FR2, and a third medium conveyance path FR3. The first medium conveyance path FR1 is a medium conveyance path facing the recording head 9 and is capable of conveying the medium in the +Y direction, which is the medium conveyance direction when recording is performed on the medium, and the opposite -Y direction. In the present embodiment, the first medium conveyance path FR1 is a medium conveyance path between the conveyance drive roller 16 and the first discharge drive roller 23.

[0035] The reversal path RR is a path for reversing the surface of the medium. In the present embodiment, the reversal path RR is a medium conveyance path between the driven roller 14a and the driven roller 14c. The second medium conveyance path FR2 is a path for guiding the medium on which recording has been performed to the reversal path RR. In the present embodiment, the second medium conveyance path FR2 is a path passing through the driven roller 14d and is a medium conveyance path between the conveyance drive roller 16 and the driven roller 14a. The third medium conveyance path FR3 is located vertically below the second medium conveyance path FR2 and is a path for guiding the medium on which recording has been performed to the reversal path RR. In the present embodiment, the third medium conveyance path FR3 is a path passing through the reversal drive roller 25 and is a medium conveyance path between the second discharge drive roller 27 and the driven roller 14a. Note that in FIG. 2, reference numeral FR4 denotes a medium conveyance path between the driven roller 14c and the conveyance drive roller 16. Hereinafter, this medium conveyance path will be referred to as the fourth medium conveyance path FR4.

[0036] In the media feed path K1, the media is fed by a feed roller 11 driven by a motor (not shown). The feed roller 11 is supported by a support member 12 that swings about a swing axis 12a. As the support member 12 swings, the feed roller 11 moves forward and backward relative to the media accommodated in the media cassette 4A. The symbol P indicates the media accommodated in the media cassette 4A.

[0037] The inversion roller 21 located downstream of the feed roller 11 is formed with the largest diameter among other rollers and curves and inverts the media. Driven rollers 14a, 14b, 14c, 14d are provided around the inversion roller 21. The media fed through the media feed paths K1 and K2 is sent to the conveyance drive roller 16 via the inversion path RR and the fourth media conveyance path FR4. The media fed through the media feed path K3 is sent to the conveyance drive roller 16 via the fourth media conveyance path FR4.

[0038] The media sent along the -Y direction through the second media conveyance path FR2 is sent to the conveyance drive roller 16 via the inversion path RR and the fourth media conveyance path FR4. Similarly, the media sent along the -Y direction through the third media conveyance path FR3 is sent to the conveyance drive roller 16 via the inversion path RR and the fourth media conveyance path FR4.

[0039] The media sent to the conveyance drive roller 16 driven by a drive source (not shown) is nipped by this conveyance drive roller 16 and a conveyance driven roller 17 that rotates passively, and is sent to the area facing the recording head 9, that is, the recording area, where recording is performed.

[0040] The carriage 8 provided with the recording head 9 is guided by a carriage guide shaft 19 extending in the X-axis direction and reciprocates in the X-axis direction by a power source (not shown). The recording head 9, which is an example of the recording unit, ejects ink onto the media as the carriage 8 moves.

[0041] A media support member 18 is provided at a position facing the recording head 9, and the medium on which recording is performed by the recording head 9 is supported by the media support member 18. Downstream of the media support member 18, a rotatably driven first discharge drive roller 23 and a driven rotatable first discharge driven roller 24 are provided. Downstream of the first discharge drive roller 23, a driven roller 29 is provided, and further downstream thereof, a rotatably driven second discharge drive roller 27 and a driven rotatable second discharge driven roller 28 are provided.

[0042] In the printer 1 having the above-described media feeding path and media conveyance path, the feeding roller 11 and the reversing roller 21 are driven by a motor (not shown), the conveyance drive roller 16 and the first discharge drive roller 23 are driven by a motor 31 (see FIG. 4), and the second discharge drive roller 27 and the reversing drive roller 25 are driven by a motor (not shown).

[0043] In addition, when recording is performed on the second surface of the medium, which is opposite to the first surface, on which recording has been performed on the first surface, the medium on which recording has been performed is sent to the reversing path RR. As the medium conveyance path at that time, in the present embodiment, either the second medium conveyance path FR2 or the third medium conveyance path FR3 can be selected. The flap 22 that can swing about the swing shaft 22a switches the conveyance destination of the medium to either the second medium conveyance path FR2 or the third medium conveyance path FR3.

[0044] The conveyance drive roller 16 is an example of an upstream roller, and the first discharge drive roller 23 is an example of a downstream roller. The first discharge drive roller 23 is provided on the first rotation shaft 36, and the conveyance drive roller 16 is provided on the second rotation shaft 40. The first rotation shaft 36 and the second rotation shaft 40 constitute a drive transmission device 30 described later. The conveyance drive roller 16 and the first discharge drive roller 23 constitute the medium conveyance device 10. In addition, in view of the aspect of conveying the medium, the entire printer 1 can also be referred to as a medium conveyance device.

[0045] The above is the media conveyance path of the printer 1. Hereinafter, the drive transmission device 30 will be described with reference to FIG. 3 and subsequent figures. The drive transmission device 30 is a device that transmits the power of the motor 31 to the endless belt 47, and includes three or more pulleys and an endless belt 47 spanned over these pulleys, with these being the minimum components. As shown in FIGS. 3 and 4, the plurality of pulleys in this embodiment are composed of a first pulley 35, a second pulley 39, a third pulley 43, and a drive pulley 33 as the fourth pulley. The first pulley 35 and the second pulley 39, the second pulley 39 and the third pulley 43, the third pulley 43 and the drive pulley 33, and the drive pulley 33 and the first pulley 35 are adjacent to each other and form linear belt sections. The first pulley 35, the second pulley 39, and the third pulley 43 are driven pulleys that rotate passively, and the drive pulley 33 is a drive pulley that rotates by the power of the motor 31.

[0046] In this embodiment, the endless belt 47 is a toothed belt with teeth formed along the belt length direction on the inner side. The first pulley 35, the second pulley 39, and the drive pulley 33 are toothed pulleys that mesh with the teeth of the endless belt 47. The third pulley 43 is a pulley without teeth formed. However, the endless belt 47 is not limited to a toothed belt, and teeth may not be formed. Also, each pulley is not limited to a toothed pulley, and teeth may not be formed.

[0047] In addition, in this embodiment, the drive transmission device 30 further includes a first rotating shaft 36, a second rotating shaft 40, a third rotating shaft 44 (see FIG. 5), a first bearing portion 52, and a second bearing portion 50a. Also, in this embodiment, the drive transmission device 30 further includes a main frame 50, a side frame 51, a swing member 53, a tension coil spring 54, and a fixing member 55.

[0048] The drive transmission device 30 is provided on the +X direction side portion of the main frame 50 that constitutes the base of the printer 1. The first rotating shaft 36, which is the rotating shaft of the first pulley 35, is supported by the first bearing portion 52. The first bearing portion 52 is provided on a side frame 51 provided on the +X-direction side surface of the main frame 50. The first pulley 35 is provided at the +X-direction shaft end portion of the first rotating shaft 36. And the +X-direction shaft end portion of the first rotating shaft 36 is a free end with respect to the first bearing portion 52. The second rotating shaft 40, which is the rotating shaft of the second pulley 39, is supported by the second bearing portion 50a. The second bearing portion 50a is integrally formed with the main frame 50. The second pulley 39 is provided at the +X-direction shaft end portion of the second rotating shaft 40. And the +X-direction shaft end portion of the second rotating shaft 40 is a free end with respect to the second bearing portion 50a.

[0049] The drive pulley 33 is attached to the motor shaft 32 of the motor 31. The third pulley 43 is a pulley that applies tension to the endless belt 47. The third pulley 43 is rotatably supported with respect to the swing member 53 via a third rotating shaft 44 (see FIG. 5). The swing member 53 is a member that swings coaxially with the motor shaft 32 by a bearing portion (not shown), and is pressed in the clockwise direction of FIG. 3 by a tension coil spring 54, which is an example of a pressing member.

[0050] A fixing member 55 is provided at a position adjacent to the swing member 53. A tooth portion 55a is formed on the fixing member 55, and the swing member 53 is fixed so as not to rotate by the engagement of a protruding regulated portion 53a formed on the swing member 53 with the tooth portion 55a.

[0051] The first pulley 35, the second pulley 39, and the drive pulley 33 are in contact with the inner surface of the endless belt 47, that is, the surface on which teeth are formed, and the third pulley 43 is in contact with the outer surface of the endless belt 47, that is, the surface on which no teeth are formed. With such a configuration, the third pulley 43 applies tension to the endless belt 47 by pushing the endless belt 47 into the inside of the endless belt 47, and thus the increase in size of the drive transmission device 30 can be suppressed.

[0052] In the first pulley 35, a first flange 37 is formed in the +X direction, and the -X direction side surface of the first flange 37 faces the +X direction side surface 47f of the endless belt 47. Also, in the second pulley 39, a second flange 41 is formed in the +X direction, and the -X direction side surface of the second flange 41 faces the side surface 47f of the endless belt 47. Further, in the third pulley 43, a third flange 45 is formed in the +X direction, and the -X direction side surface of the third flange 45 faces the side surface 47f of the endless belt 47. Note that although a flange is also formed on the -X direction side surface of the third pulley 43, the description thereof will be omitted hereinafter. In the drive pulley 33, no flange is formed in the present embodiment.

[0053] Next, as shown in FIG. 5, a plurality of linear belt sections are formed in the endless belt 47 between two pulleys. The first belt section 47a is a belt section formed between the drive pulley 33 and the first pulley 35, and the symbol L1 represents the length of the first belt section 47a. The second belt section 47b is a belt section formed between the first pulley 35 and the second pulley 39, and the symbol L2 represents the length of the second belt section 47b. The third belt section 47c is a belt section formed between the second pulley 39 and the third pulley 43, and the symbol L3 represents the length of the third belt section 47c. The fourth belt section 47d is a belt section formed between the third pulley 43 and the drive pulley 33, and the symbol L4 represents the length of the fourth belt section 47d. Note that the length of each belt section is the length of the free region where the endless belt 47 does not contact the flange or the pulley.

[0054] In the present embodiment, among the belt sections, the length L2 of the second belt section 47b is the longest. Next, the length L1 of the first belt section 47a is long, and then the length L3 of the third belt section 47c is long. And the length L4 of the fourth belt section 47d is the shortest.

[0055] Here, as described above, the shaft end of the first rotating shaft 36 provided with the first pulley 35 is a free end, and the shaft end of the second rotating shaft 40 provided with the second pulley 39 is also a free end. Therefore, both have a so-called cantilever beam structure. For this reason, the first rotating shaft 36 and the second rotating shaft 40 are structured to be easily deflected toward the inside of the endless belt 47. In FIG. 6, line AC1 is the axis center line of the first rotating shaft 36 where no deflection occurs, and line BC1 is the axis center line of the second rotating shaft 40 where no deflection occurs. When the first rotating shaft 36 is deflected by the tension of the endless belt 47, both the first rotating shaft 36 and the second rotating shaft 40 are deflected toward the inside of the endless belt 47. Therefore, the axis center line of the first rotating shaft 36 from the first bearing portion 52 toward the shaft end side becomes as shown by line AC2. Similarly, the axis center line of the second rotating shaft 40 from the second bearing portion 50a toward the shaft end side becomes as shown by line BC2. Moreover, in the initial state of assembly, the axis center lines of all the pulleys provided in the drive transmission device 30 are all parallel in the X-axis direction.

[0056] When the first rotating shaft 36 and the second rotating shaft 40 are deflected as described above, the first pulley 35 and the second pulley 39 are inclined toward the inside of the endless belt 47, and as a result, the endless belt 47 moves in the +X direction. And due to such movement of the endless belt 47, the endless belt 47 strongly contacts the flange provided on the pulley, making it easy for the endless belt 47 to break. Moreover, the movement of the endless belt 47 in the X-axis direction can also be caused by the deflection of only one of the first rotating shaft 36 and the second rotating shaft 40, that is, it can occur even if only one of the first rotating shaft 36 and the second rotating shaft 40 has a cantilever beam structure. Also, the movement of the endless belt 47 in the X-axis direction is not limited to the deflection of the first rotating shaft 36 or the second rotating shaft 40, and can also be caused by other factors, for example, the deformation of the main frame 50.

[0057] Therefore, in the drive transmission device 30, among the plurality of belt sections, a first flange 37 provided on a first pulley 35 that forms the longest second belt section 47b and does not form the shortest fourth belt section 47d is given the function of restricting the movement of the endless belt 47 in the +X direction. In FIG. 6, the side surface 47f of the endless belt 47 is in contact with the first flange 37, that is, the distance Y1 between the first flange 37 and the side surface of the endless belt 47 is zero. Of course, the distance Y1 does not necessarily have to be zero. Also, the distance Y2 is the distance between the second flange 41 and the side surface 47f of the endless belt 47, and the distance Y3 is the distance between the third flange 45 and the side surface 47f of the endless belt 47. In the present embodiment, as an example, the distance Y2 is smaller than the distance Y3. And since the distance Y1 is set to be even smaller than the smaller distance Y2 among the other distances Y2 and Y3, when the endless belt 47 attempts to move in the +X direction, the first flange 37 will undertake the function of restricting said movement.

[0058] Here, in the endless belt 47, the shorter the length of the belt section, the stronger the contact between the endless belt 47 and the flange provided on the pulley forming the belt section, and the more prone the endless belt 47 is to breakage. However, as described above, the first flange 37 with the smallest distance from the side surface 47f of the endless belt 47, that is, the first flange 37 that restricts the movement of the endless belt 47 in the axial direction (X-axis direction) when the endless belt 47 rotates, is provided on the first pulley 35 that forms the longest second belt section 47b and does not form the shortest fourth belt section 47d among the plurality of belt sections. Thereby, the force with which the endless belt 47 contacts the first flange 37 can be suppressed, and thereby, while suppressing the breakage of the endless belt 47, the movement of the endless belt 47 in the axial direction (X-axis direction) can be restricted.

[0059] Note that the restriction of the movement of the endless belt 47 in the +X direction is mainly contributed by the first flange 37, but even if the other flanges contact the endless belt 47 and the other flanges restrict the movement of the endless belt 47 in the +X direction to some extent, it may be acceptable.

[0060] Also, in the present embodiment, since the first pulley 35 forms the longest second belt section 47b among the plurality of belt sections and the second-longest first belt section 47a, the force with which the endless belt 47 contacts the first flange 37 can be further suppressed, and thus the breakage of the endless belt 47 can be more reliably suppressed.

[0061] Also, in the present embodiment, the outer diameter of the first pulley 35 is larger than the minimum outer diameter among the plurality of pulleys. In the present embodiment, the outer diameter of the second pulley 39 is the largest, followed by the first pulley 35, then the third pulley 43, and the drive pulley 33 is the smallest. Note that the pulley outer diameter is the outer diameter of the cylindrical portion around which the endless belt 47 is wound, not the outer diameter of the flange. Here, the smaller the pulley outer diameter, the smaller the flange outer diameter, so when the endless belt 47 contacts the flange, stress concentration is likely to occur, leading to breakage of the endless belt 47. However, as described above, since the outer diameter of the first pulley 35 is larger than the minimum outer diameter among the plurality of pulleys, breakage of the endless belt 47 caused by the above-described stress concentration can be suppressed.

[0062] Note that in the present embodiment, as described above, with respect to the first bearing portion 52, the shaft end portion of the first rotating shaft 36 on which the first pulley 35 is provided is a free end, and with respect to the second bearing portion 50a, the shaft end portion of the second rotating shaft 40 on which the second pulley 39 is provided is a free end. Therefore, both have a so-called cantilever beam structure and are easily bent by the tension of the endless belt 47. For this reason, the above-described movement of the endless belt 47 in the +X direction is likely to occur, and breakage of the endless belt 47 is likely to occur due to the strong contact of the endless belt 47 with the flange. However, since the flange (first flange 37) that regulates the movement of the endless belt 47 in the +X direction as described above is provided on the first pulley 35, while suppressing breakage of the endless belt 47, the movement of the endless belt 47 in the axial direction (X-axis direction) can be regulated.

[0063] In this embodiment, the first pulley 35 and the second pulley 39 form the longest second belt section 47b, and the intervals Y1 between the first flange 37 and the endless belt 47 and Y2 between the second flange 41 and the endless belt 47 are both smaller than the interval Y3 between the third flange 45 of the third pulley 43 and the endless belt 47. Therefore, the force for the endless belt 47 to contact the first flange 37 and the force to contact the second flange 41 can be suppressed, the breakage of the endless belt 47 at each flange can be suppressed, and the movement of the endless belt 47 in the axial direction (X-axis direction) can be restricted.

[0064] The drive transmission device 30 described above can also be modified as follows. (1) The flange for restricting the movement of the endless belt 47 in the +X direction may be the second flange 41 provided on the second pulley 39. That is, the interval Y2 in FIG. 6 may be the smallest interval. In this case, the second flange 41 will be provided on the second pulley 39 having the largest outer diameter among the plurality of pulleys. Thereby, the breakage of the endless belt 47 caused by the stress concentration described above can be more reliably suppressed.

[0065] (2) The third pulley 43 may be provided so as to be displaceable in the axial direction (X-axis direction). For example, the axial dimension of the third rotating shaft 44 is made larger than the width of the third pulley 43 (width in the X-axis direction), and the third pulley 43 is provided slidably with respect to the third rotating shaft 44. At this time, the third pulley 43 is made displaceable in the axial direction (X-axis direction) so that the surface 45a of the third flange 45 facing the endless belt 47 in FIG. 6 can be positioned in the +X direction with respect to the surface 37a of the first flange 37 facing the endless belt 47. Thereby, even if the endless belt 47 moves in the +X direction due to the deflection of the first rotating shaft 36 and the second rotating shaft 40, the force for the endless belt 47 to contact the third flange 45 when the endless belt 47 rotates becomes smaller than the force for the endless belt 47 to contact the first flange 37 and the force to contact the second flange 41. As a result, the breakage of the endless belt 47 associated with the strong contact of the endless belt 47 with the third flange 45 can be suppressed.

[0066] (3) Further, the configuration of the above (2) can be rephrased as follows. That is, among the plurality of belt sections formed on the endless belt 47, the third pulley 43, which is a pulley forming the shortest fourth belt section 47d and does not form the longest second belt section 47b, is provided as a displacement pulley so as to be displaceable in the axial direction (X-axis direction). Due to the displacement of the third pulley 43, when the endless belt 47 rotates, the force with which the endless belt 47 contacts the third flange 45 is smaller than the force with which it contacts the flanges provided on the other pulleys. That is, in the endless belt 47, the shorter the length of the belt section, the stronger the endless belt 47 contacts the flange when the pulley forming the belt section is provided with a flange, and the easier the endless belt 47 is to break. However, since the pulley provided at such a position is displaced in the axial direction, breakage of the endless belt 47 can be suppressed.

[0067] (4) The plurality of pulleys included in the drive transmission device 30 are composed of four pulleys in this embodiment, but may be composed of three pulleys, or may be composed of five or more pulleys. Further, the plurality of pulleys may not include a drive pulley and may all be driven pulleys. Further, the plurality of pulleys may not include a pulley (corresponding to the third pulley 43 in the above embodiment) that applies tension to the endless belt.

[0068] As described above, the medium conveyance device 10 according to this embodiment includes a drive transmission device 30 and at least one roller that conveys a medium and is driven by the drive transmission device 30. The printer 1 includes a recording head 9 that records on a medium and the medium conveyance device 10. The printer 1 also includes a drive transmission device 30, a conveyance drive roller 16 that is a roller driven by the second pulley 39 of the drive transmission device 30 and is located upstream of the recording head 9 in the medium conveyance path, and a first discharge drive roller 23 that is a roller driven by the first pulley 35 of the drive transmission device 30 and is located downstream of the recording head 9 in the medium conveyance path.

[0069] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. For example, in the above embodiment, an example in which the drive transmission device is applied to a printer, which is an example of a recording device, has been described, but it is not limited thereto. For example, in a post-processing device that performs post-processing such as binding processing on a medium on which recording has been performed, the transport roller that transports the medium may be driven by the above-described drive transmission device. Further, for example, in an image reading device typified by a scanner, if it is a flatbed type scanner, the belt mechanism that moves the reading sensor extending in the main scanning direction in the sub-scanning direction may be configured by the above-described drive transmission device. Further, when the scanner is provided with a sheet feed mechanism, the transport roller that transports the document may be driven by the above-described drive transmission device.

Explanation of Signs

[0070] 1... Inkjet printer, 2... Apparatus main body, 3... Scanner unit, 4A, 4B... Media storage cassette, 5... Operation unit, 6... Discharge tray, 7... Cover, 8... Carriage, 9... Recording head, 10... Media conveyance device, 11... Feed roller, 12... Support member, 12a... Swing shaft, 12b... Cam contact portion, 14a~14d... Driven roller, 16... Conveyance drive roller, 17... Conveyance driven roller, 18... Media support member, 19... Carriage guide shaft, 21... Reverse roller, 22... Flap, 23... First discharge drive roller, 24... First discharge driven roller, 25... Reverse drive roller, 26... Reverse driven roller, 27... Second discharge drive roller, 28... Second discharge driven roller, 29... Driven roller, 30... Drive transmission device, 31... Motor, 32... Motor shaft, 33... Drive pulley, 35... First pulley, 36... First rotating shaft, 37... First flange, 39... Second pulley, 40... Second rotating shaft, 41... Second flange, 43... Third pulley, 44... Third rotating shaft, 45... Third flange, 47... Endless belt, 47a... First belt section, 47b... Second belt section, 47c... Third belt section, 47d... Fourth belt section, 47f... Side surface, 50... Main frame, 50a... Second bearing portion, 51... Side frame, 52... First bearing portion, 53... Swing member, 53a... Restricted portion, 54... Tension coil spring, 55... Fixed member, 55a... Tooth portion, K1, K2, K3... Media feed path, FR1... First media conveyance path, FR2... Second media conveyance path, FR3... Third media conveyance path, RR... Reverse path

Claims

1. A plurality of three or more pulleys, An endless belt stretched over the plurality of pulleys, having a plurality of linear belt sections formed between two of the pulleys, Comprising, Among the plurality of belt sections, a first pulley that forms the longest belt section and does not form the shortest belt section is provided with a first flange, The distance between the first flange and the side surface of the endless belt is smaller than the smallest distance among the distances between the flanges provided on the other pulleys and the side surface of the endless belt, A pulley that constitutes the plurality of pulleys, a second pulley that forms the longest belt section together with the first pulley, A first rotating shaft that is the rotating shaft of the first pulley and has the first pulley provided at an end of the shaft, A second rotating shaft that is the rotating shaft of the second pulley and has the second pulley provided at an end of the shaft, A first bearing portion for receiving the first rotating shaft, A second bearing portion for receiving the second rotating shaft, Comprising, At least one of the shaft ends of the first rotating shaft provided with the first pulley with respect to the first bearing portion and the shaft ends of the second rotating shaft provided with the second pulley with respect to the second bearing portion is a free end, The plurality of pulleys include a third pulley that applies tension to the endless belt and is adjacent to the second pulley, A pulley provided on the drive shaft of the motor, a fourth pulley that is adjacent to the third pulley and the first pulley, The lengths of the belt sections are in the order of the belt section between the third pulley and the fourth pulley, the belt section between the second pulley and the third pulley, the belt section between the first pulley and the fourth pulley, and the belt section between the first pulley and the second pulley, from longest to shortest, The outer diameters of the first pulley and the second pulley are larger than the outer diameter of the third pulley, The outer diameter of the third pulley is larger than the outer diameter of the fourth pulley, The second pulley is provided with a second flange facing the side surface of the endless belt, The third pulley is provided with a third flange facing the side surface of the endless belt, Both the distance between the first flange and the side surface of the endless belt and the distance between the second flange and the side surface of the endless belt are smaller than the distance between the third flange and the side surface of the endless belt, A drive transmission device characterized by the above.

2. A plurality of three or more pulleys, An endless belt stretched over the plurality of pulleys, the endless belt having a plurality of linear belt sections formed between two of the pulleys, A first flange is provided on a first pulley that forms the longest belt section among the plurality of belt sections and does not form the shortest belt section, When the endless belt rotates, the first flange restricts movement of the endless belt in the axial direction of the pulley, A pulley that constitutes the plurality of pulleys, a second pulley that forms the longest belt section together with the first pulley, A first rotating shaft that is the rotating shaft of the first pulley and has the first pulley provided at an axial end portion, A second rotating shaft that is the rotating shaft of the second pulley and has the second pulley provided at an axial end portion, A first bearing portion that receives the first rotating shaft, A second bearing portion that receives the second rotating shaft, Comprising, At least one of the axial end portions of the first rotating shaft provided with the first pulley with respect to the first bearing portion and the axial end portions of the second rotating shaft provided with the second pulley with respect to the second bearing portion is a free end, The plurality of pulleys include a third pulley that applies tension to the endless belt and is adjacent to the second pulley, A pulley provided on the drive shaft of the motor, including a fourth pulley adjacent to the third pulley and the first pulley, The lengths of the belt sections increase in this order: the belt section between the third pulley and the fourth pulley, the belt section between the second pulley and the third pulley, the belt section between the first pulley and the fourth pulley, and the belt section between the first pulley and the second pulley, The outer diameters of the first pulley and the second pulley are larger than the outer diameter of the third pulley, The outer diameter of the third pulley is larger than the outer diameter of the fourth pulley, A second flange facing the side surface of the endless belt is provided on the second pulley, A third flange facing the side surface of the endless belt is provided on the third pulley, The distance between the first flange and the side surface of the endless belt and the distance between the second flange and the side surface of the endless belt are both smaller than the distance between the third flange and the side surface of the endless belt, A drive transmission device characterized by this.

3. In the drive transmission device according to claim 1 or claim 2, the first pulley forms the longest belt section and the second longest belt section among the plurality of belt sections. A drive transmission device characterized by this.

4. In the drive transmission device according to any one of claims 1 to 3, the outer diameter of the first pulley is larger than the minimum outer diameter among the plurality of pulleys. A drive transmission device characterized by this.

5. In the drive transmission device according to claim 4, the outer diameter of the first pulley is the maximum outer diameter among the plurality of pulleys. A drive transmission device characterized by this.

6. In the drive transmission device according to any one of claims 1 to 5, both the shaft end portion of the first rotating shaft provided with the first pulley with respect to the first bearing portion and the shaft end portion of the second rotating shaft provided with the second pulley with respect to the second bearing portion are free ends. A drive transmission device characterized by this.

7. The drive transmission device according to any one of claims 1 to 6, A roller for conveying a medium, comprising at least one roller driven by the drive transmission device. A medium conveyance device characterized by this.

8. A recording unit for recording on a medium, The medium conveyance device according to claim 7. A recording device characterized by this.

9. A recording unit for recording on a medium, The drive transmission device according to any one of claims 1 to 6, A roller driven by the second pulley of the drive transmission device, which is an upstream roller located upstream of the recording unit in the medium conveyance path, A roller driven by the first pulley of the drive transmission device, which is a downstream roller located downstream of the recording unit in the medium conveyance path. A recording device characterized by this.

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