JP2010032917A - Drive transmitting device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive transmitting device which prevents a printing defect caused by irregular pitches of gears and irregular cycles of a developing roller and a photoreceptor drum by preventing eccentricity of a rotary shaft on which a coupling is provided, and to provide an image forming apparatus including the drive transmitting device. <P>SOLUTION: In the drive transmitting device having a coupling mechanism for transmitting drive from a drive source to an attachable/detachable unit, a coupling member for transmitting the drive from the drive source is provided on the rotary shaft of the coupling mechanism. The coupling member has gear faces formed in two directions different in a helical direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drive transmission device having a coupling mechanism that engages with a part of a detachable member that is detachably provided in the device and transmits drive, and an image forming apparatus including the drive transmission device.

  A conventional image forming apparatus using an electrophotographic process includes an image forming unit in which an image forming unit in which a photosensitive drum, a charging roller acting on the photosensitive drum, a developing roller, and a cleaning mechanism are integrated is mounted on the apparatus main body, and a recording medium using the electrophotographic process An image is formed on the screen. An image forming apparatus including a process cartridge type image forming unit that is detachably attached to the main body of the image forming apparatus is used.

  In general, an image forming unit has a developing roller for developing toner on a photosensitive drum as an electrostatic latent image carrier, and the developing roller attaches toner to the electrostatic latent image on the photosensitive drum. It is disposed at a position close to the drum while being in contact with or maintaining a minute distance, and is rotated by a driving device. At this time, the photosensitive drum and the developing roller have gears or couplings at their ends, and are connected to a driving source such as a motor so as to rotate.

In the case of being connected by a gear, in order to reduce the rotation unevenness due to the meshing vibration of the gear, the spur gear is generally changed to a helical gear and connected. Even when coupled by a coupling, a gear is provided on the rotating shaft of the coupling, and the gear is connected to a drive source as a helical gear (see, for example, Patent Document 1). The reason for this configuration is that the helical gear can set the gear meshing ratio to be large, and can reduce rotation unevenness due to meshing vibration.
JP 2000-7166 (paragraphs “0015” to “0019”, FIG. 2)

  However, in the above-described conventional technology, when the gears are connected with a helical gear, the gear meshing ratio can be set large, but since a thrust force is generated, vibration in the thrust direction is likely to occur. Therefore, when the helical gear is arranged coaxially with the coupling, the force that moves the helical gear in the direction perpendicular to the torsional angle acts, and vibration in the thrust direction is likely to occur. There is a problem in that a coupling is arranged at the end, and the coupling is rotated by one-side support, so that the coupling is easily decentered, and the connected developing roller or the photosensitive drum is likely to cause uneven rotation.

If the rotation axis of the coupling rotates in an eccentric manner as described above, it causes rotation irregularities of the connected developing roller or photosensitive drum, and causes printing defects due to gear pitch irregularities or developing roller and photosensitive drum roller irregularities. There is a problem of end.
An object of the present invention is to solve such a problem, and to prevent eccentricity of a rotating shaft provided with a coupling, and to prevent occurrence of printing defects due to uneven pitch of a gear and uneven roller cycle of a developing roller and a photosensitive drum. It is an object of the present invention to provide a transmission device and an image forming apparatus including the drive transmission device.

For this reason, the drive transmission device according to the present invention is a drive transmission device having a coupling mechanism for transmitting the drive from the drive source to the detachable unit, and a connection for transmitting the drive from the drive source to the rotating shaft of the coupling mechanism. A member is provided, and the connecting member includes a gear surface formed in two directions having different oblique tooth directions.
An image forming apparatus according to the present invention includes the drive transmission device that transmits driving to a detachable image forming unit.

  According to the present invention as described above, it is possible to prevent eccentricity of the rotating shaft provided with the coupling mechanism and to prevent printing defects due to uneven pitch of the gears and uneven roller cycles of the developing roller and the photosensitive drum. .

  Embodiments of a drive transmission device and an image forming apparatus according to the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram of an electrophotographic color printer which is an image forming apparatus according to the first embodiment.
In FIG. 2, the image forming apparatus 1 is capable of color printing, and has four color image forming units 11a, 11b, and 11c of Y (yellow), M (magenta), C (cyan), and K (black). 11d are arranged at substantially equal intervals, and an LED head 12 as an exposure head is disposed with a predetermined gap between the image forming units 11a, 11b, 11c, and 11d. Since each image forming unit 11 (11a, 11b, 11c, 11d) has the same structure, one of them will be described below.

  The medium tray 15 stores a medium 16 as a recording sheet, and is provided with a separation roller 17 for separating the medium 16 one by one. In the medium running path for conveying the medium 16 separated and sent one by one by the separation roller 17, a transfer roller 18, a transfer belt 19 for transferring the toner to the medium 16, and the toner transferred on the medium 16 A fixing unit 20 for fixing the toner, and discharge rollers 21 and 22 for discharging the medium 16 on which the toner is fixed. The medium 16 discharged outside the apparatus by the discharge rollers 21 and 22 is held on the stacker cover 23.

  Further, the image forming unit 11 is configured to be detachable from the printer, stores therein different color toners (yellow, magenta, cyan, black) 27 and transfers the photosensitive drum 13 as an image carrier. The developing roller 14 as a developer carrying member and the charging roller 24 for uniformly and uniformly charging the surface of the photosensitive drum 13 are arranged so as to contact the photosensitive drum 13. .

Further, a supply roller 25 for supplying the toner 27 and a developing blade 26 for thinning the toner 27 are disposed so as to contact the developing roller 14.
FIG. 1 is a sectional view of a drive transmission device for an image forming unit in the first embodiment.
In FIG. 1, an image forming unit 11 transmits a rotational drive from a drive source such as a motor provided in the printer main body to the photosensitive drum 13 and the developing roller 14, so that a helical gear, a yamaba gear, a coupling mechanism, and the like are used. It has the drive transmission device which becomes.

The helical gear 50 is provided at the end of the rotating shaft of the photosensitive drum 13, and the helical gear 51 is provided at the end of the rotating shaft of the developing roller 14.
The helical gear 52 is provided so as to mesh with the helical gear 51, and has a coupling receiving portion 52d at the end of its rotation shaft. The coupling receiving portion 52d and the coupling 61 provided on the printer main body side Are detachably connected to form a coupling mechanism.

  The YAMABA gear 53 as a connecting member provided on the printer main body side includes a gear surface formed in two directions having different oblique tooth directions, and one end of the rotation shaft is pivotally supported by a plate 58 of the printer main body. The other end is connected to the coupling 61, and a spring 60 for biasing the coupling 61 in the direction of the coupling receiving portion 52d is disposed between the YAMABA gear 53 and the coupling 61.

The YAMABA gear 54 is disposed so that one end of its rotation shaft is supported by the plate 58 and meshes with the YAMABA gear 53, and is connected to a drive source such as a motor (not shown) via an intermediate gear. . Accordingly, the YAMABA gear 54 can transmit the drive from the drive source to the coupling 61 via the YAMABA gear 53.
A helical gear 55 provided on the printer main body is disposed so as to mesh with the helical gear 50, and is connected to a driving source such as a motor (not shown) via an intermediate gear.

Here, the gear train from the drive source to the Yamaha gear 53 and the helical gear 50 will be described based on the explanatory diagram of the gear train in the first embodiment of FIG.
In FIG. 6, the helical gear 55 and the helical gear 50 are connected to the driving source 70 via an intermediate gear 71 a from a driving source 70 such as a motor disposed in the image forming apparatus 1. Further, the yamaba gear 54 and the yamaba gear 53 are connected to the drive source 70 from the drive source 70 through intermediate gears 71b, 71c, 71d. Therefore, the helical gear 51 connected to the drive source 70 via the Yamaba gear 53, the coupling 61, and the helical gear 52 is not directly connected to the helical gear 50. At this time, each of the Yamaba gears and the helical gears is set to have a meshing ratio of 2 or more in order to reduce meshing vibration of the gears.

  Returning to the description of FIG. 1, reference numerals 56 and 59 denote side plates in the image forming apparatus 1 for supporting the mounted image forming unit 11. Further, the plate 63 provided on the printer main body is in contact with the coupling 61 and moves the coupling 61 in the direction of the rotation axis. The coupling 61 is brought into contact with the plate 63 with a spring 60. Is being energized. A block 62 is disposed between the side plate 56 and the plate 63.

The plate 58 is disposed in the image forming apparatus 1 and rotatably supports the yamaba gear 53 and the yamaba gear 54. The plate 56 is also disposed in the image forming apparatus 1 and supports the helical gear 55 so as to be rotatable. is doing.
Further, 32 is a developing roller unit having the developing roller 14, 35 is a chassis of the developing roller unit 32, 33 is a shaft that supports the photosensitive drum 13 and cannot rotate itself. The chassis 35 and the shaft 33 are supported by side plates 30 and 31 together with the developing roller unit 32.

The spring 37 and the spring 38 as elastic members urge both ends of the developing roller unit 32 so as to contact the photosensitive drum 13 and maintain an appropriate nip width between the developing roller 14 and the photosensitive drum 13. .
As described above, the image forming unit 11 is integrated with the developing roller unit 32 and the side plates 30 and 31, and is detachable from the image forming apparatus 1. In the mounted image forming apparatus 1, the shaft 33, and The protrusions 30 a and 31 a provided on the side plates 30 and 31 are supported by the side plates 56 and 59.

The image forming apparatus 1 that allows the image forming unit 11 to be detachable includes the plate 58 and the side plate 56, and between the side plate 56 and the right side of the side plate 59 including the side plate 59 in FIG. The helical gear 55 is supported on the side plate 56 of the image forming apparatus 1 and is disposed on the image forming apparatus 1 side so as to mesh with the helical gear 50.
FIG. 3 is a perspective view of the image forming unit in the first embodiment, and shows a state in which the side plate 30 supports the developing roller unit 32.

  In FIG. 3, support protrusions 35b and 35c provided on the chassis 35 are respectively fitted into grooves 30b and 30c formed on the side plate 30, and the support protrusion 35c rotates the developing roller 14 and the photosensitive drum 13 within the groove 30c. Energized by a spring 37 as an elastic member in a direction indicated by an arrow 37b of an extension line connecting the axes, the developing roller 14 as a developer carrying member is brought into contact with the photosensitive drum 13 as an image carrying member with a predetermined force. An appropriate nip width between the developing roller 14 and the photosensitive drum 13 is maintained.

Reference numeral 37a denotes a fixing member for fixing the spring 37 in the groove 30c, and the protrusion 37c provided in the fixing member 37a is fitted into a hole 30d provided in the groove 30c to fix the spring 37. It is like that.
The opposite end of the developing roller unit 32 is also supported in the same manner, and is biased by a spring 38 as an elastic member so that an appropriate nip width between the developing roller 14 and the photosensitive drum 13 is maintained. Yes.

FIG. 4 is an exploded perspective view showing the configuration of the drive transmission device in the first embodiment, and shows the configuration of the coupling 61 and the gears arranged coaxially with the coupling 61.
In FIG. 4, the helical gear 52 is provided with a coupling receiving portion 52d at its end, and projections 52b and 52c are provided inside the coupling receiving portion 52d. On the other hand, a protrusion 61a is provided at the end of the coupling 61, and the protrusion 61a is inserted into the coupling receiving portion 52d and engages with the protrusions 52b and 52c inside the coupling receiving portion 52d. .

Further, a groove 61b is provided at the opposite end of the coupling 61, and a protrusion 53a provided at the end of the YAMABA gear 53 is inserted, and the protrusion 53a engages with the groove 61b to rotate. Can be transmitted.
Therefore, the helical gear 52 is coaxially connected to the YAMABA gear 53 by the coupling 61, and the coupling 61 and the helical gear 52 rotate simultaneously with the helical gear 52.

The operation of the above configuration will be described.
First, the printing operation of the image forming apparatus 1 will be described with reference to FIG.
The image forming apparatus 1 that has received a print command from an external device such as a personal computer (not shown) separates the medium 16 contained in the medium tray 15 one by one by the separation roller 17 and conveys the medium 16 to the transfer belt 19 by the conveyance roller 18. To do.

At this time, the supply roller 25 of the image forming unit 11 is rotated by a driving source (not shown) to supply the toner 27 onto the developing roller 15. On the other hand, the developing roller 15 is rotated by a driving force transmitted from a driving source (not shown) and supplied with toner 27.
The toner 27 on the developing roller 15 is formed in a thin layer by the developing blade 26 and is charged by a power source (not shown). Thereafter, the photosensitive drum 13 whose surface is charged by the charging roller 24 is exposed by the exposure head 12, and the toner 27 in the image forming unit 11 moves to the exposure unit, and the exposure unit is developed.

Further, the toner image developed on the photosensitive drum 13 by the transfer belt 19 is transferred to the medium 16, and then fixed on the medium 16 by the fixing unit 20, and is discharged onto the stacker cover 23 outside the image forming apparatus 1 by the discharge rollers 21 and 22. To be discharged.
Next, driving of the image forming unit 11 will be described with reference to FIGS. 1, 3, 4, and 6.

In FIG. 6, when the drive source 70 rotates in the direction indicated by the arrow 70a, the helical gear 50 that is driven via the intermediate gear 71a and the helical gear 55 rotates in the direction indicated by the arrow 13e, and the photosensitive drum 13 is shown in FIG. It rotates in the direction indicated by the arrow 13e in FIG.
At this time, when the drive source 70 rotates in the direction indicated by the arrow 70a in FIG. 6, the yamaba that is driven via the intermediate gears 71b, 71c, 71d and the yamaba gear 54 (rotates in the direction indicated by the arrow 54a in FIG. 1). The helical gear 52 driven by the gear 53 and the coupling 61 rotates in the direction indicated by the arrow 52a in FIGS. 6, 1, 3 and 4, and the helical gear 51 and the developing roller 14 are also shown in FIG. And it rotates in the direction shown by the arrow 14e in FIG.

  The image forming unit 11 is detachable from the image forming apparatus 1. However, when the image forming unit 11 is removed from the image forming apparatus 1, a cover provided in the image forming apparatus 1 is opened or a motor or the like (not shown) is driven. The source 62 moves the block 62 in the direction indicated by the arrow 62a as shown in FIG. 5, and the inclined portion of the block 62 contacts the inclined portion of the plate 63 to move the plate 63 in the direction indicated by the arrow 63a.

  When the plate 63 is moved in the direction indicated by the arrow 63a, the plate 63 comes into contact with the protruding portion of the coupling 61, and the coupling 61 is also moved to the YAMABA gear 53 side supported by the plate 58 of the image forming apparatus 1 indicated by the arrow 62a. As a result, the projection 61a of the coupling 61 is detached from the side plate 56 and is drawn into the YAMABA gear 53 side supported by the plate 58, so that the image forming unit 11 can be attached and detached.

As described above, the gear provided on the rotation shaft of the coupling 61 is the YAMABA gear 53 formed so that the torsion angles of the inclined teeth are opposite to each other, so that the force acting in the thrust direction can be canceled out. Thus, the coupling 61 can be rotated without being eccentric.
In addition, the meshing rate of the gear can be set to 2 or more as in the helical gear.

As described above, in the first embodiment, the gear provided on the rotating shaft of the coupling mechanism is a Yamaba gear formed so that the torsion angles of the inclined teeth are opposite to each other. The force acting in the direction can be canceled out, and the effect that the coupling mechanism can be rotated without decentering is obtained.
Accordingly, the eccentricity and rotational vibration unevenness of the coupling mechanism in the image forming unit can be reduced at the same time, and printing defects due to the uneven pitch of the gears of the image forming unit and the roller cycle of the rollers of the developing roller and the photosensitive drum can be prevented. The effect that it can be obtained.

FIG. 7 is a sectional view of the drive transmission device for the image forming unit in the second embodiment, and FIG. 8 is a sectional view of the helical gear and the coupling in the second embodiment.
Note that parts similar to those of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
7 and 8, reference numerals 80a, 80b, 81 and 82 denote helical gears provided as separate bodies, which are provided in place of the Yamaha gears 53 and 54 of the first embodiment.

A helical gear 80a (a driving gear for transmitting driving from a driving source not shown) as a connecting member has an end portion of the rotating shaft connected to the coupling 61, and a coupling is provided between the helical gear 80a and the coupling 61. A spring 60 for urging 61 in the direction of the coupling receiving portion 52d is provided.
Further, a helical gear 80b (auxiliary gear) is provided as a connecting member so as to be coaxial with the helical gear 80a, and the helical gear 80a and the helical gear 80b rotate integrally and have an oblique tooth direction. The gear faces are formed in two different directions, and the diameter of the helical gear 80b is smaller than the diameter of the helical gear 80a.

Further, the helical gear 80a and the helical gear 80b are formed so that the torsion angles of the inclined teeth are opposite to each other in order to cancel the force acting in the thrust direction.
The helical gear 81 is disposed so as to mesh with the helical gear 80a, and is connected to a driving source such as a motor (not shown) via an intermediate gear. Therefore, the helical gear 81 can transmit the drive from the driving source to the coupling 61 via the helical gear 80a.

  A helical gear 82 as an auxiliary connecting member is disposed on the downstream side of the helical gears 80a and 80b with respect to the drive source so as to mesh with a helical gear 80b which is a single oblique gear, and the axial direction of the coupling 1 The inclined teeth are formed in one direction to reduce the force generated in the. The helical gear 82 is not provided for the purpose of transmitting drive, but is provided for canceling the force acting in the thrust direction.

In addition, a spring 83 as an elastic member that biases in the thrust direction toward the plate 58 is provided at the end of the rotating shaft of the helical gear 82, and the end is fixed by the plate 84. The reason why the spring 83 is provided is to generate a load in the axial direction of the helical gear 82.
As described above, the configuration of the second embodiment is provided with the helical gears 80a, 80b, 81 and the helical gear 82 instead of the YAMABA gears 53, 54 of the configuration of the first embodiment.

Since the operation of the above-described configuration is the same as that of the first embodiment, the description thereof is omitted.
As shown in FIG. 8, two-stage helical gears 80a and 80b are provided on the rotating shaft of the coupling 61 so that the torsion angles of the inclined teeth are opposite to each other, and the helical gear 80a has a helical gear 81 and a helical gear 80b. The helical gears 81 and 82 are provided so that the helical gear 82 meshes, the thrust force generated by the meshing of the helical gear 81 and the helical gear 80a is Fa, the thrust load generated by the spring 60 is Fb, the helical gear 80b and the helical gear 82. Assuming that Fc is a thrust load generated by the spring 83 in the thrust direction generated by the meshing, Fa−Fb≈Fc is set so that the thrust force of the coupling 61 is reduced as in the first embodiment. To be able to.

By doing so, high-precision meshing between the gears is required, and the thrust force of the coupling 61 can be reduced with an inexpensive helical gear without using an expensive Yamaba gear.
As described above, in the second embodiment, the eccentricity of the coupling mechanism and the rotational vibration unevenness in the image forming unit can be reduced at the same time without using a high-accuracy yamaba gear. In this way, it is possible to prevent printing defects due to the uneven pitch and the uneven roller cycle of the developing roller and the photosensitive drum.

  The present invention has been described with reference to the example of the drive transmission device of the image forming unit. However, the present invention is not limited to this, and can be applied to a drive transmission device having a coupling, such as a color or monochrome copying machine, LED printer, or laser beam printer. The present invention can also be applied to image forming apparatuses used for facsimiles, MFPs (Multi Function Peripherals), and the like.

Sectional drawing of the drive transmission apparatus of the image forming unit in 1st Example 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. 1 is a perspective view of an image forming unit according to a first embodiment. The disassembled perspective view which shows the structure of the drive transmission device in 1st Example. Sectional view of Yamaba gear and coupling in the first embodiment Explanatory drawing of the gear train in the first embodiment Sectional drawing of the drive transmission apparatus of the image forming unit in 2nd Example Sectional drawing of the helical gear and coupling in the second embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11, 11a, 11b, 11c, 11d Image forming unit 12 Exposure head 13 Photosensitive drum 14 Developing roller 15 Media tray 16 Medium 17 Separation roller 18 Conveyance roller 19 Transfer belt 20 Fixing unit 21, 22 Discharge roller 23 Stacker cover 24 Charging roller 25 Supply roller 26 Developing blade 27 Toner 30, 31 Side plate 30a, 31a Protrusion 32 Developing roller unit 33 Shaft 35 Chassis 37, 38 Spring 50, 51, 52, 55 Hasuba gear 53, 54 Yamaba gear 56, 59 Side Plate 58, 63 Plate 60 Spring 61 Coupling 62 Block 70 Drive source 71 Intermediate gear 80a, 80b, 81, 82, 83 Hasuba gear 83 Spring 84 Plate

Claims (6)

In the drive transmission device having a coupling mechanism for transmitting the drive from the drive source to the detachable unit,
A coupling member for transmitting the drive from the drive source is provided on the rotating shaft of the coupling mechanism,
The connecting member includes a gear surface formed in two directions with different oblique tooth directions. The drive transmission device according to claim 1, wherein
A drive transmission device characterized in that the connecting member is an angle gear. The drive transmission device according to claim 1, wherein
2. The drive transmission device according to claim 1, wherein the connecting member is two inclined gears having different inclined tooth directions. The drive transmission device according to any one of claims 1 to 3,
The drive transmission device according to claim 1, wherein the coupling member has a meshing ratio of 2 or more with a meshed gear. An image forming apparatus comprising the drive transmission device according to claim 1. The image forming apparatus according to claim 5.
A detachable image forming unit having a developer carrier connected by the coupling mechanism and an image carrier on which the developer carrier abuts;
An image forming apparatus, wherein the image forming unit is provided with an elastic member for bringing the developer carrier into contact with the image carrier with a predetermined force.

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