JP4325121B2 - Rotation drive device for image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation driving device for an image forming apparatus, and more particularly to a technique capable of reducing rotation unevenness of an image carrier.
[0002]
[Prior art]
In an electrophotographic image forming apparatus, a plurality of elements are rotationally driven to form an image. When the so-called pitch unevenness occurs due to the non-uniformity of the rotational speed of the image carrier, especially the rotational speed of these elements, the image quality is greatly deteriorated. Japanese Patent Application Laid-Open No. 09-080840 discloses a technique for reducing pitch unevenness that occurs in gear meshing in anticipation of gear sag. That is, in the present invention, in the gear train in which the first helical gear and the second helical gear are engaged, the standard torsion angle of the gear train is α, and the second helical gear of the first helical gear at the time of rotational driving is used. When the tilt angle of the shaft center with respect to δ1 is δ1, the mesh surface side twist angle α1 of the first helical gear has a mutual difference δ1 with respect to the standard twist angle α so as to have a relationship of α1−α≈δ1. It has been.
[0003]
However, the conventional rotary drive device described above is disadvantageous in terms of cost because it is necessary to create a gear with a special torsion angle every time the arrangement of gear trains and the load torque of elements differ.
[0004]
In order to reduce pitch unevenness, backlash that contributes to pitch unevenness is also removed by applying a relative force that presses the meshing gears together. However, with this method, it is difficult to make the shaft thicker in an image forming apparatus that is required to be lighter and more compact, and the applied force may cause gear collapse, which may increase pitch unevenness. It is difficult to adopt because there is a concern that the tooth bottom contact may occur.
[0005]
In order to reduce the size and cost of the image forming apparatus, power is transmitted from a single drive source to one gear, and a plurality of gears are meshed with this to split the power to each element. Conventionally, no attention has been paid to the way of branching.
[0006]
[Problems to be solved by the invention]
In order to avoid such disadvantages from the cost aspect, the present invention uses a standard gear that can be obtained at low cost, and has a rotational drive device for an image forming apparatus that is less affected by gear collapse and can reduce image pitch unevenness. The issue is to provide. Still another object of the present invention is to reduce pitch unevenness in an image forming apparatus without using the backlash removing means as described above. It is a further object of the present invention to provide a rotary drive device that reduces this occurrence based on the knowledge that branching causes pitch unevenness.
[0008]
[Means for Solving the Problems]
The above problem is solved by the following means. That is, the solving means of the first invention includes one branching source gear and a plurality of elements including at least the image carrier for causing the image forming apparatus to function by being driven, respectively. Are fixed to the respective input shafts for transmitting rotational power from each of the plurality of branch destination gears meshed with the branch source gears, and connected to a drive source for driving the branch source gears to rotate. A rotation drive device for an image forming apparatus comprising a source gear, wherein the resultant force of each of the plurality of branch destination gears and the drive source gear exerted on the branch source gear is an input shaft of the image carrier. The torque applied to the plurality of branch destination gears and the drive source gear and the arrangement of these gears are adjusted so that they are substantially parallel to the tangent line between the branch destination gear fixed to the branch source gear and the branch source gear. It has been. And, in the solving means of the second invention, the rotary driving device of the first aspect, to the plurality of elements, in addition to the image bearing member includes a developing device, a transfer device and the fixing device .
[0009]
Solution of the third invention, and one branch source gear, for functioning of the image forming apparatus by which each is driven, the plurality of elements including at least an image bearing member, the rotation from the branch source gear A plurality of branch destination gears that are fixed to the respective input shafts for transmitting power, each meshing with the branch source gear, and a drive source gear that is connected to the drive source and rotationally drives the branch source gear. And the resultant force of each of the plurality of branch destination gears and the drive source gear exerted on the branch source gear is fixed to the input shaft of the image carrier. The torque applied to the plurality of branch destination gears and the drive source gear and the arrangement of these gears are adjusted so that the branch source gears are separated from the branch destination gears. Then, the solution according to the fourth invention, the rotary driving device of the third invention, the above plurality of elements, in addition to the image bearing member includes a developing device, a transfer device and the fixing device .
[0010]
Solution of the fifth invention, and one branch source gear, for functioning of the image forming apparatus by which each is driven, the plurality of elements including at least an image bearing member and the developing device, the branch In order to transmit rotational power from the original gear, it is fixed to each input shaft, each of which is connected to a plurality of branch destination gears meshed with the branch original gear, and a drive source, and rotationally drives the branch original gear A rotation driving device for an image forming apparatus, wherein a force applied to the branch source gear by a gear fixed to the input shaft of the developing device is the plurality of branch destination gears and the drive A tangent line between a branch destination gear fixed to the input shaft of the image carrier and the branch source gear so that each of the source gears is in the same direction as the resultant force exerted on the branch source gear or in the opposite direction. In As will be parallel, the torque exerted on the plurality of branch target gear and the drive source gear, and the arrangement of these gears is adjusted. Then, in the solution according to the sixth invention, in the rotary driving device of the fifth invention, the plurality of elements, in addition to the image bearing member and the developing device, includes the transfer device and the fixing device Yes.
[0011]
The branch source gear that branches into a plurality of elements receives a tangential force at each meshing position by the load of each element. The resultant force of these forces translates the branching source gear in a certain direction. According to these inventions, the direction of translational movement of the branch source gear is determined by adjusting the arrangement of the branch destination gear meshing with the branch source gear and the load amount of the element.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
Hereinafter, the present invention will be described by taking an embodiment of a small laser printer as an image forming apparatus. FIG. 1 is a drive system diagram showing a drive system of each element of the laser printer. The laser printer includes elements such as an image carrier (photosensitive drum) PC, a developing device DV, a fixing device FX, a paper feeding device PF, a transport device PT, and a timing roller TR. These elements are transmitted from the drive source gear gm fixed to the shaft of one motor M to the large-diameter gear g01, and are all driven by the branching source gear g00 that is kinetically integrated with this gear. Note that the individual operations and functions of these elements are not special ones different from those of a normal image forming apparatus, and thus further description thereof is omitted.
[0013]
A branch destination gear g11, a branch destination gear g21, a branch destination gear g31, a branch destination gear g41, and a branch destination gear g51 are engaged with the gear g00. These gears serve as input shafts to elements constituting the image forming apparatus (in this example, a laser printer). FIG. 1 shows a power transmission system of a developing system, an image forming system, a paper feeding / conveying system, a timing system, and a fixing system surrounded by a dotted line. FIG. 2 shows, as an example, a branch destination gear g21 meshing with the gear g00 and a power transmission mechanism for rotating the image carrier PC using the branch destination gear g21 as an input shaft. The power of the branch destination gear g21 is connected to the gear g22 and the gear g23 fixed to the image carrier PC.
[0014]
The branch destination gear g11 is an input shaft to the developing device DV, and is sequentially coupled to the gears g12, g13, g14, and g15, and the developing roller DR is rotationally driven by the gear g15. The gear g14 is also meshed with the gear g16. Further, power is transmitted to the gears g16, g17, g18, and g19, and the cleaning roller CR to which the gear g19 is fixed is driven to rotate.
[0015]
The branch destination gear 21 is an input shaft of an image forming system including the image carrier PC, and power is transmitted to the gears g21, g22, g23, and g24. The gear g23 is fixed to the image carrier PC, and the gear g24 is fixed to the transfer roller.
[0016]
The branch destination gear g31 is an input shaft of the fixing device FX, and is sequentially connected to the gears g32, g33, and g34, and the fixing roller FR coupled to the gear g34 is rotationally driven.
[0017]
The branch destination gear g41 is an input shaft of the timing device, and the timing roller TR to which the gear g42 is fixed is driven to rotate.
[0018]
The branch destination gear g51 is an input shaft of the paper feed device PF and the transport device PT, and is sequentially connected to the branch destination gear g51, gears g52, g53, and g54, and the first paper feed roller PF1 is rotationally driven. . The gear g53 meshes with the gear g55, and the first transport roller TR1 is rotationally driven. The branch destination gear g51 further transmits power to the gears g56, g57, g58, and g59, and the second paper feed roller PF2 to which the gear g59 is fixed is driven. The gear g60 integrated with the gear g58 further transmits power to the gears g61 and g62, and rotationally drives the second transport roller TR2 fixed to the gear g61 and the gear g62, respectively.
[0019]
In the image forming apparatus according to the present invention, a plurality of elements including at least an image carrier (for example, an image carrier) for causing the image forming apparatus to function by being driven by one branch source gear as described above. Body PC, developing device DV, fixing device FX, paper feeding device PF, transport device PT, timing roller TR, etc.) are fixed to the respective input shafts for transmitting rotational power from the branching gear g00. A plurality of branch destination gears g11, g21, g31, g41, and g51 that mesh with the branch source gear g00 are provided. In order to drive the branch source gear g00, a drive source gear gm is provided which is connected to a drive source (motor M) and rotationally drives it.
[0020]
FIG. 3 shows vectors F0 to F5 representing the force F received by the branching gear g00 and the force applied to the branching gear g00 by the input shaft of the above elements in a conventional rotary drive device for an image forming apparatus. It is represented by. This resultant force is a force that eventually tries to tilt the shaft that supports the gear g00 (and the gear g01), and the shaft is slightly bent by this force. When the shaft has a difference in strength around the shaft, the shaft center is shifted by bending, and the rotational speed of the branch destination gears g11 to g51 is uneven. Therefore, as shown in FIG. 3, when the absolute value of the resultant force is large, the drive rotation received from the branch source gear g00 varies. This appears as image pitch unevenness.
[0021]
In the first embodiment, the resultant force of the translational movement forces F1, F2, F3, F4, F5, and F0 that the plurality of branch destination gears g11, g21, g31, g41, and g51 and the drive source gear gm exert on the branch source gear g00. The torque applied to the plurality of branch destination gears and the drive source gear gm so that F is substantially zero, and the arrangement of these gears (that is, the angular position at which the branch destination gears g11 to g51 mesh with the branch source gear g00). ) Is adjusted. As a result, the resultant force F can be made substantially zero as shown in FIG.
Normally, as the backlash between the gear meshes becomes smaller, the pitch accuracy is extremely affected. In this embodiment, such a state can be avoided.
[0022]
Example 2
Since Example 2 to Example 4 are the same as Example 1 except for differences in the forces F to F5, overlapping description will not be given. FIG. 5 is a diagram for explaining the second embodiment. Similarly to FIGS. 3 and 4, forces F1 to F5 that the branch destination gears g11 to g51 and the drive source gear gm apply to the branch source gear g00 (and g01). And the resultant force F is shown. In this example, these torques and positions are adjusted so that the resultant force F is applied substantially in parallel to the force F2 (tangent) applied to the branch source gear g00 by the branch destination gear g21 serving as the input shaft of the image carrier PC. . At this time, the backlash between the branch source gear g00 and the branch destination gear g21 which is an input of the image carrier PC does not substantially change.
Normally, as the backlash between the gear meshes becomes smaller, the pitch accuracy is extremely affected. In this embodiment, such a state can be avoided. Furthermore, in this embodiment, it is possible to ensure that at least the backlash of the photoconductor series (imaging system) does not change. In such a case, the arrangement of units of other series has a degree of freedom compared to the first embodiment. Space can be used effectively. Further, even when the resultant force changes due to the torque fluctuation of each unit, the backlash does not change, and stability against torque variation is improved.
[0023]
Example 3
FIG. 6 is a diagram for explaining the third embodiment. Similarly to FIGS. 3 to 5, the forces F1 to F5 that the branch destination gears g11 to g51 and the drive source gear gm apply to the branch source gear g00 (and g01). And the resultant force F is shown. In this example, these torques and positions are such that the resultant force F of the translational movement force applied to the branch source gear g00 is applied in the direction in which the branch source gear g00 is separated from the branch destination gear g21 serving as the input shaft of the image carrier PC. It has been adjusted.
Normally, as the backlash between the gear meshes becomes smaller, the pitch accuracy is extremely affected. In this embodiment, such a state can be avoided. Furthermore, it is possible to ensure that at least the backlash of the photoconductor series (image forming system) does not become small. In such a case, the arrangement of units of other series is more flexible than in the second embodiment, and the space is effectively used. can do. Further, even when the resultant force changes due to the torque fluctuation of each unit, the backlash is not reduced, and stability against torque variation is improved.
[0024]
Example 4
FIG. 7 is a diagram for explaining the fourth embodiment, and in the same way as FIGS. 3 to 6, the forces F1 to F1 applied to the branch source gear g00 (and g01) by the branch destination gears g11 to g51 and the drive source gear gm. F5 and the resultant force F are shown. In this example, the translational movement force F1 applied to the branch source gear g00 by the branch destination gear g11 as an input to the developing device DV, for example, the toner cartridge, is the same direction as the resultant force F applied to the branch source gear g00 by F0 to F5 or These torques and positions are adjusted so that the direction is 180 degrees opposite and the resultant force F is substantially parallel to the tangent (F2) between the branch source gear g00 and the branch destination gear g21 branching to the image carrier PC. ing. At this time, the backlash between the branch source gear g00 and the branch destination gear g21 does not substantially change.
Normally, as the backlash between the gear meshes becomes smaller, the pitch accuracy is extremely affected. However, in this embodiment, such a state can be avoided. In such a case, in Example 4, even if the developing system torque fluctuates due to toner consumption or the like, the backlash between the gear meshes is not reduced, and the backlash of the photosensitive member series is not reduced. can do.
[0025]
【The invention's effect】
As described above, according to the present invention, the torque of the branch destination gear that is an input to the element device constituting the image forming apparatus and the position thereof can be adjusted without using special parts. According to the configuration, it is possible to more effectively reduce the image pitch unevenness as compared with the conventional image forming apparatus.
[Brief description of the drawings]
FIG. 1 is a drive system diagram showing a drive system of each element of a laser printer.
FIG. 2 is an explanatory diagram showing a branch destination gear g21 and a power transmission mechanism for rotating the image carrier PC having the branch destination gear g21 as an input shaft.
FIG. 3 is an explanatory diagram showing a resultant force F applied to a branching source gear g00 and a force (F0 to F5) applied to an input shaft of each element in a rotation driving device for a conventional image forming apparatus. It is.
FIG. 4 is a diagram similar to FIG. 3 and is an explanatory diagram for Example 1 of the present invention.
FIG. 5 is a diagram similar to FIG. 3 and is an explanatory diagram for Example 2 of the present invention.
FIG. 6 is a diagram similar to FIG. 3 and is an explanatory diagram for Example 3 of the present invention.
FIG. 7 is a diagram similar to FIG. 3 and is an explanatory diagram for Embodiment 4 of the present invention.
[Explanation of symbols]
g00 Branching source gear g01 Large diameter gears g11, g21, g31, g41, g51 Branching destination gear gm Driving source gear M Motor CR Cleaning roller DR Developing roller DV Developing device FR Fixing roller FX Fixing device PC Image carrier PF Feeding device PT Transport device TR Timing rollers PF1, PF2 Paper feed rollers TR1, TR2 Transport rollers

Claims (6)

One branch source gear,
Each of them is fixed to each input shaft for transmitting rotational power from the branching gear to a plurality of elements including at least an image carrier for causing the image forming apparatus to function by being driven. A plurality of branch destination gears meshing with the branch source gear;
A drive source gear connected to the drive source and for rotationally driving the branching source gear;
In a rotary drive device for an image forming apparatus comprising:
The resultant force of the forces exerted on the branching source gear by the plurality of branching destination gears and the drive source gear is substantially tangential to the branching destination gear fixed to the input shaft of the image carrier and the branching source gear. A rotational drive device for an image forming apparatus, wherein the torque applied to the plurality of branch destination gears and the drive source gear and the arrangement of these gears are adjusted so as to be parallel to each other. The rotation drive device for an image forming apparatus according to claim 1 ,
The rotation driving device for an image forming apparatus, wherein the plurality of elements include a developing device, a transfer device, and a fixing device in addition to the image carrier. One branch source gear,
Each of them is fixed to each input shaft for transmitting rotational power from the branching gear to a plurality of elements including at least an image carrier for causing the image forming apparatus to function by being driven. A plurality of branch destination gears meshing with the branch source gear;
A drive source gear connected to the drive source and for rotationally driving the branching source gear;
In a rotary drive device for an image forming apparatus comprising:
The resultant force of each of the plurality of branch destination gears and the drive source gear exerted on the branch source gear is in the direction of separating the branch source gear from the branch destination gear fixed to the input shaft of the image carrier. Thus, the torque applied to the plurality of branch destination gears and the drive source gear, and the arrangement of these gears are adjusted, and the rotational drive device for an image forming apparatus. The rotational drive device for an image forming apparatus according to claim 3 ,
The rotation driving device for an image forming apparatus, wherein the plurality of elements include a developing device, a transfer device, and a fixing device in addition to the image carrier. One branch source gear,
A plurality of elements including at least an image carrier and a developing device for causing the image forming apparatus to function by being driven are fixed to the input shafts to transmit rotational power from the branching source gear. A plurality of branch destination gears each meshing with the branch source gear;
A drive source gear connected to the drive source and for rotationally driving the branching source gear;
In a rotary drive device for an image forming apparatus comprising:
The force exerted on the branching gear by the gear fixed to the input shaft of the developing device is
Each of the plurality of branch destination gears and the drive source gear is in the same direction as the resultant force of the force exerted on the branch source gear or in the opposite direction, and
To be substantially parallel to the tangent line between the branch destination gear fixed to the input shaft of the image carrier and the branch source gear,
A rotational drive device for an image forming apparatus, wherein torque applied to the plurality of branch destination gears and the drive source gear, and arrangement of these gears are adjusted. The rotation drive device for an image forming apparatus according to claim 5 ,
The rotary driving device for an image forming apparatus, wherein the plurality of elements include a transfer device and a fixing device in addition to the image carrier and the developing device.

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