JP2010025128A - Belt-driven transmission device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt tension adjustment mechanism and an image forming device provided with the same, stably maintaining specified tension without depending on belt elongation or the like caused by deterioration with age. <P>SOLUTION: A belt-driven transmission device for transmitting a driving force by laying a timing belt 23 between a drive pulley 21 and a driven pulley 22 includes a rotor 31 movable for push-pressing the belt 23, and a compression spring 34 for pushing the rotor 31 to the belt 23. The compression spring 34 regulates the movement of the rotor 31. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a belt drive transmission device for transmitting a driving force by a belt and an image forming apparatus including the belt drive transmission device.

  Conventionally, in a belt transmission device in which a timing belt is wound around a toothed pulley to perform belt transmission, when the belt tension decreases, the engagement between the belt tooth portion and the pulley tooth portion disappears, so-called jumping phenomenon occurs. There is a problem.

  As a configuration for suppressing the jumping phenomenon, as shown in FIG. 7, there is one in which the position of one of the toothed pulleys 101 and 102 meshing with the timing belt 100 can be adjusted. In addition, as shown in FIG. 8, there is an idler pulley 103 provided on the timing belt 100 that can be adjusted in position so as to apply tension to the belt 100. These are for adjusting and fixing the positions of the toothed pulley 101 and the idler pulley 103 so that a predetermined tension is obtained in the timing belt 100.

  As another configuration, as shown in FIG. 9, the back side of the loose side of the timing belt 100 is pressed by a tension roller 105 urged by a spring 104 or the like, and a tension corresponding to the driving force is applied to the belt 100. There is a configuration.

  However, in the configuration shown in FIGS. 7 and 8, since the toothed pulley 101 or the idler pulley 103 is fixedly arranged, the tension needs to be adjusted during assembly. Therefore, a special assembling method is required to obtain a prescribed tension. Further, when the belt is stretched with time, the tension is lowered and a desired tension cannot be obtained, and a jumping phenomenon may occur.

  On the other hand, as shown in FIG. 9, it is easy to obtain a prescribed tension in the configuration in which the tension roller 105 is urged by the spring 104 or the like. However, in this case, if the pulley that is stopped suddenly accelerates and the transmission torque of the timing belt changes abruptly, or if the pulley thermally expands in a high-temperature environment, etc. It cannot be suppressed by the tension urged by etc. As a result, a jumping phenomenon may occur.

  Therefore, in the configuration as shown in FIG. 9, a stopper 107 is provided on a holder 106 that holds a tension roller 105 for biasing the timing belt 100. Thereby, the lower limit value of the stroke of the holder 106 is limited so that the jumping phenomenon does not occur.

  However, as shown in FIG. 9, in the configuration in which the stopper 107 is provided, when the belt vibrates, the stopper 107 hits the support member 108 for regulating the sliding direction of the holder 106, and a collision noise is generated.

  In an image forming apparatus, drive transmission is often performed using a timing belt, which is often used for noise reduction. For this reason, when the impact sound of the stopper is generated as described above, this sound becomes annoying sound. Furthermore, vibrations at the time of collision may be transmitted through the side plates and the like, causing image defects.

  The present invention has been made in view of the above points, and an object of the present invention is to control a belt tension adjusting mechanism capable of stably maintaining a prescribed tension without being influenced by the elongation of the belt due to changes over time, and image formation including the same. A device is provided.

  A representative means in the present invention for solving the above-described problem is to press the belt in a belt drive transmission device that transmits an endless belt between a drive pulley and a driven pulley to transmit a driving force. It has a movable pressing member and urging means for pressing the pressing member against the belt, and the urging means regulates movement of the pressing member.

  When the elastic body is configured by a compression spring, a configuration is used in which the contact height of the compression spring is limited as a lower limit value of the stroke of the urging member. Since the compression spring is compressed stepwise and becomes a rigid body when the contact height is reached, no collision noise is generated as compared with a conventional configuration having a stopper. In particular, when an image forming apparatus is used, image propagation does not occur because propagation of vibration due to a collision is reduced.

  When the elastic body is configured by an elastic deformation portion on the urging member, a configuration is used in which a limit value of the elastic deformation is limited as a lower limit value of the stroke of the urging member. Since the elastic portion is gradually deformed and becomes a rigid body when the elastic portion hits, the collision sound is not generated as compared with the conventional configuration having a stopper. In particular, image defects due to collision do not occur in the image forming apparatus. Furthermore, since the elastic member is provided on the biasing member, the number of parts can be reduced and the cost can be reduced.

  When the urging member is formed of a thermoplastic elastomer, or when a buffer member represented by urethane is used as a stopper, the impact noise can be reduced by the damper function of the elastic body. Particularly in an image forming apparatus, vibration due to a collision can be reduced, so that no image defect occurs.

[First Embodiment]
Next, as a best mode for carrying out the present invention, an example in which a belt drive transmission device is used as an image forming apparatus in a printer will be described.

[Entire configuration of image forming apparatus]
First, the overall configuration of the image forming apparatus will be described with reference to FIG. The laser beam printer P, which is an image forming apparatus of the present embodiment, forms an image on a recording medium (for example, a recording sheet, an OHP sheet, a cloth, etc.) 1 by an electrophotographic image forming process.

  A charging roller 3, a developing roller 4, and the like are disposed around a rotatable drum-shaped photosensitive member (photosensitive drum) 2, and these are configured as a process cartridge 5 that can be attached to and detached from the apparatus main body. When the process cartridge 5 is mounted, the photosensitive drum 2 and the like are drivingly connected to the apparatus main body via a coupling (not shown) and can be driven to rotate.

  When forming an image, the rotating photosensitive drum 2 is uniformly charged by the charging roller 3, and a laser beam corresponding to the image information is irradiated from the optical unit 6 to form an electrostatic latent image. The electrostatic latent image is developed with toner by a developing unit having a developing roller 4 and the like to be visualized.

  Synchronously with the formation of the toner image, the recording medium 1 loaded in the feeding cassette 10 by driving and rotating the feeding roller 7, the conveying roller 8 and the registration roller pair 9 is transferred to the nip between the photosensitive drum 2 and the transfer roller 11. To the part. Then, a transfer bias is applied to the transfer roller 11 to transfer the toner image on the photosensitive drum 2 to the recording medium 1.

  The recording medium 1 that has received the transfer of the toner image is conveyed to the fixing means 12 and is heated and pressed to fix the toner image, and then discharged onto the discharge tray 14 by the discharge roller 13.

[Belt drive transmission device]
A driving force is transmitted to the photosensitive drum 2, the feeding roller 7, the conveying roller 8, and the fixing unit 12 of the image forming apparatus by a belt driving transmission device. Next, the configuration of the belt drive transmission device according to the present embodiment will be described with reference to FIG.

  FIG. 1 is an explanatory perspective view of a belt drive transmission device for transmitting drive to the image forming apparatus of the present embodiment.

  A drive pulley 21 is attached to the drive shaft of the motor 20. An endless timing belt 23 is stretched between the driving pulley 21 and a driven pulley 22 that is rotatably attached, and the driving force of the motor 20 is driven via the driving pulley 21 and the timing belt 23. Is transmitted to 22. The rotating shaft 21a of the driving pulley 21 and the rotating shaft 22a of the driven pulley 22 are arranged in parallel. Further, the drive pulley 21 and the driven pulley 22 are toothed pulleys, and the timing belt 23 is also formed with teeth that mesh with it.

  A gear 24 is formed integrally with the driven pulley 22, and the gear 24 meshes with two idler gears 25 and 26. Further, gears 27 and 28 mesh with one idler gear 25, and gear 29 meshes with the other idler gear 26. The gear 27 transmits driving force to the process cartridge 5, and the gear 28 transmits driving force to the feeding roller 7 and the conveying roller 8. The gear 29 transmits driving force to the fixing unit 12 and the discharge roller 13.

  The belt drive transmission device of the present embodiment is provided with a tension adjusting means 30 for adjusting the tension of the timing belt 23 in order to prevent a jumping phenomenon that occurs when the meshing between the tooth portion of the belt and the tooth portion of the pulley is lost.

  As shown in FIG. 2, the tension adjusting means 30 has a rotary member 31 that is a pressing member for pressing the belt surface of the timing belt 23 from the outside, and is rotatably attached to a holder 32. A holder 32 which is a holding member for holding the rotating body 31 is attached to the support member 33 so as to be movable. Further, a compression spring 34 is attached between the holder 32 and the support member 33. The compression spring 34 serves as an urging means for pressing the rotating body 31 against the timing belt 23, and is constituted by a coil spring.

  The rotating body 31 urged by the compression spring 34 presses the timing belt 23, whereby tension is applied to the timing belt 23 to prevent a jumping phenomenon. Note that if the urging force by the compression spring 34 is too strong, the noise generated when the teeth of the timing belt 23 are bitten will increase. Conversely, if the urging force by the compression spring 34 is weak, a jumping phenomenon may occur. Therefore, the urging force of the compression spring 34 is set to be an appropriate force while paying attention to the above points.

  The rotating body 31 is movable within a range where the holder 32 is supported by the support member 33. When the rotating body 31 moves to the uppermost movement limit, the locking portions (not shown) provided on the holder 32 and the support member 33 are locked to each other so that the holder 32 does not fall off the support member 33. It has become.

  On the other hand, the lower limit of movement at which the rotating body 31 moves most inside the support member 33 is regulated by the compression spring 34. The compression spring 34 is compressed when the rotating body 31 is pressed. When the coils constituting the spring are brought into close contact with each other, the compression limit becomes incapable of further compression, resulting in a rigid body. In this embodiment, the holder 32 can move in the support member 33 until the compression spring 34 reaches the compression limit, and when the compression limit is reached, the holder 32 cannot move any further. That is, when the rotating body 31 is pressed, the compression spring 34 is compressed, but when the coil reaches the compression limit where the coil is in close contact, the compression of the holder 32 is restricted by the compression spring 34 because no further compression is possible. This is the lower limit of movement.

  As described above, since the lower limit of movement of the rotating body 31 is regulated by the compression spring 34, there is no collision noise generated when the stopper collides with the support portion as in the prior art. In addition, since vibration due to collision does not occur, image defects due to this do not occur.

[Second Embodiment]
Next, an apparatus according to a second embodiment will be described with reference to FIGS. Since the basic configuration of the apparatus of the present embodiment is the same as that of the first embodiment, a duplicate description is omitted. Here, the configuration of the tension adjusting means in the belt drive transmission device that is a feature of the present embodiment will be described. Moreover, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above.

  As shown in FIG. 4, in the tension adjusting means of the present embodiment, a rotating body 31 that is a pressing member for pressing the belt surface of the timing belt 23 from the outside is rotatably attached to a holder 32. The support member 33 is movably attached. An elastic portion 32a that can be elastically deformed is integrally formed at the lower portion of the holder 32 of the present embodiment. The elastic portion 32a serves as an urging means for pressing the rotating body 31 against the timing belt 23. The two leg portions are formed so as to project symmetrically downward and the lower end is formed on the support member 33. It is in contact with the corner of the recess. When the rotating body 31 is pressed, the elastic portion 32a is elastically deformed and urges the rotating body 31 to push upward. Thereby, the timing belt 23 is urged by the rotating body 31, and tension is applied.

  In the above configuration, when the rotating body 31 moves downward, the elastic portion 32a is elastically deformed. When the rotating body 31 moves to a predetermined position, the elastic portion 32a moves in the direction of arrow a as shown in FIG. By deforming and hitting each other and hitting the support member 33, elastic deformation becomes impossible. At this time, the elastic portion 32a is in a rigid state. For this reason, the elastic part 32a is not elastically deformed any further, and its position becomes the lower limit of movement of the rotating body 31.

  Even in the present embodiment, since the lower limit of movement of the rotating body 31 is regulated by the elastic portion 32a, there is no collision sound generated when the stopper collides with the support portion as in the prior art. In addition, since vibration due to collision does not occur, image defects due to this do not occur.

  Furthermore, in this embodiment, the holder itself that holds the rotating body 31 has a configuration that applies a biasing force as compared with the first embodiment described above, and therefore, a compression spring is not necessary. Therefore, the number of parts can be reduced, and the same effect can be obtained at low cost. It is also possible to configure the elastic part 32a as a separate member from the holder 32.

[Third Embodiment]
Next, an apparatus according to a third embodiment will be described with reference to FIG. Since the basic configuration of the apparatus of the present embodiment is also the same as that of the first embodiment, a duplicate description is omitted, and here, the configuration of the tension adjusting means in the belt drive transmission device that is a feature of the present embodiment will be described. Moreover, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above.

  As in the first embodiment, the tension adjusting means of the present embodiment is configured such that a rotating body 31 that can be moved to press the timing belt 23 is rotatably attached to a holder 32, and the holder 32 can be moved to a support member 33. Is attached. The holder 32 is urged upward by a compression spring 34.

  Here, the holder 32 of the present embodiment is formed with a stopper 32b capable of contacting the support member 33. The stopper 32b comes into contact with the support member 33 when the holder 32 holding the rotating body 31 is lowered to a predetermined position, and restricts further lowering. That is, the lower limit of movement of the rotating body 31 is set by the stopper 32b.

  Further, in the present embodiment, a buffer portion 35 for buffering the impact of the collision is provided at the end portion of the stopper 32b, that is, the contact portion with the support member 33. In the present embodiment, the buffer portion 35 is made of a thermoplastic elastomer so as to buffer the impact at the time of stopper collision. The lower limit of movement of the rotating body 31 is defined by a value when the buffer portion 35 is elastically deformed and reaches a compression limit.

  In the present embodiment, since the buffer portion 35 is softer than when the holder is formed of a resin material, the collision noise can be reduced. Further, since the impact at the time of collision is absorbed by the damper function of the thermoplastic elastomer, vibration is not transmitted to the side plate or the like even in the image forming apparatus, so that an image defect does not occur.

  In the present embodiment, an example in which the buffer portion 35 is made of a thermoplastic elastomer has been shown. However, this may be any member that can cushion an impact, and the same effect can be obtained even if it is made of, for example, urethane. be able to.

FIG. 3 is a perspective explanatory view of a belt drive transmission device for transmitting drive to the image forming apparatus according to the first embodiment. It is a schematic explanatory drawing of the belt drive transmission apparatus which concerns on 1st Embodiment. 1 is an explanatory diagram of an overall configuration of an image forming apparatus. It is a model explanatory drawing of the belt drive transmission apparatus which concerns on 2nd Embodiment. It is explanatory drawing of the tension adjustment means which concerns on 2nd Embodiment. It is a model explanatory drawing of the belt drive transmission apparatus which concerns on 3rd Embodiment. It is a model explanatory drawing of the belt drive transmission device which concerns on a prior art. It is a model explanatory drawing of the belt drive transmission device which concerns on a prior art. It is a model explanatory drawing of the belt drive transmission device which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording medium 2 ... Photosensitive drum 3 ... Charging roller 4 ... Developing roller 5 ... Process cartridge 6 ... Optical unit 7 ... Feeding roller 8 ... Conveying roller 9 ... Registration roller pair
10 ... Feed cassette
11… Transfer roller
12… Fixing means
13… discharge roller
14… discharge tray
20… Motor
21… Drive pulley
21a, 22a ... Rotating shaft
22… driven pulley
23… Timing belt
24… Gear
25, 26 ... idler gear
27, 28, 29 ... Gear
30 ... Tension adjusting means
31… Rotating body
32… Holder
32a ... Elastic part
32b… Stopper
33… Support member
34… Compression spring
35… Buffer part

Claims (7)

In a belt drive transmission device that transmits an endless belt between a drive pulley and a driven pulley to transmit a driving force,
A pressing member movable to press the belt;
Biasing means for biasing the pressing member to the belt;
Have
The belt drive transmission device, wherein the urging means regulates the movement of the pressing member.   2. The belt drive transmission device according to claim 1, wherein the biasing means is a compression spring, and restricts the movement of the pressing member when the compression spring is compressed to a compression limit.   The biasing means is an elastically deformable elastic portion provided in a holding member that holds the pressing member, and restricts the movement of the pressing member when the elastic portion becomes inelastically deformable. The belt drive transmission device according to claim 1. In a drive transmission device that transmits an endless belt between a drive pulley and a driven pulley to transmit a driving force,
A pressing member movable to press the belt;
Biasing means for biasing the pressing member to the belt;
A stopper capable of coming into contact with the support member to restrict the movement of the pressing member;
Have
A belt drive transmission device comprising a buffer portion at a contact portion between the stopper and the support member.   The belt drive transmission device according to claim 4, wherein the buffer portion is made of a thermoplastic elastomer.   The belt drive transmission device according to claim 4, wherein the buffer portion is made of urethane. In an image forming apparatus that forms an image on a sheet by transmitting a driving force by a belt drive transmission device,
7. An image forming apparatus comprising the belt drive transmission device according to claim 1 as the belt drive transmission device.

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