JP2002351284A - Drive unit for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce malfunction occasioned when a shaft is molded with a resin in a drive unit for an image forming device, and grade up the picture quality by improving the rotational accuracy of a gear and protecting an enclosure against a shock or the like. SOLUTION: The resin is used for integrally forming to provide a boss 101 and a rib 102 in an enclosure 9 for the housing which acts as the principal component of the drive unit. A rigid shaft 103 by which a reduction gear 3 is rotated and supported is screwed to be fastened to the boss 101 using a screw 104. The rib 102 is provided with the function working as a stopper which protects the reduction gear 3 from slipping out of place on the side of the enclosure 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive unit of an image forming apparatus which integrally holds a gear, a rotating shaft, a bearing, and the like, and is detachably mountable on a housing forming an apparatus body of the image forming apparatus.

[0002]

2. Description of the Related Art In a driving unit of an image forming apparatus, it is relatively easy to mount a unit housing on a casing which forms a main body of the image forming apparatus after passing a gear or a pulley through a shaft fixed to the unit housing. Yes, it is widely practiced. In addition, it is also possible to integrally form a shaft for holding the gear with the unit housing of the drive unit made of resin, by selecting an appropriate molding material.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 1-276151 (Patent Publication No. 2652034), in order to improve the image quality of an image forming apparatus, a gear train for driving a photoconductor is made independent and other It is also widely practiced to prevent the occurrence of rotation unevenness due to unit load fluctuations.

FIG. 1 is a front view showing a gear train near a motor in such a conventional drive unit. FIG. 2 is a right side sectional view (A) of the conventional drive unit in FIG. 1 and a housing of the drive unit. FIG. 3 is a cross-sectional view showing a state where the drive unit is mounted on a main body housing, FIG. 3 is a front cross-sectional view of a flange joint viewed from a rotation shaft side, and FIG. FIG. 4 is a detailed cross-sectional view of a front cross-sectional view (C) as viewed from the shaft side, a perspective view of the same leaf spring (D), and FIG.

[0005] As shown in Figs. 1 and 2 (B), a housing 1, which is a main component of the drive unit, has a motor 2 as shown in Figs.
11 for positioning and inserting the bosses, four bosses 12 for screwing the bosses 11, fixed shafts 13, 14, 1 for rotatably supporting the reduction gears 3, 4 and the idler gear 6.
6, a fixed shaft (not shown) for rotatably supporting the reduction gear 8 and the idler gears 107 and 108 and the like are integrally formed of resin. The reduction gears 3 and 8 and the idler gear 6 are connected to the gear shaft 20 of the motor 2.
And 4 have a function of driving the photoconductor unit, the reduction gear 8 has a function of driving the transport roller, and the idler gear 6 has a function of driving the developing unit.

The drive unit supports two rotary shafts, and the rotary shaft 70 rotates integrally with the gear 7 by a pin 78 shown in FIG. A ball bearing 74 is sandwiched therebetween, and a joint 71 urged by a compression spring 73 is provided beyond the ball bearing 74.
2 supports them integrally. Here, the integrated shaft 70 and the like are axially supported on the housing 1 by sliding bearings 76 at outer ends. The other rotating shaft 50 is
Like the rotating shaft 70, the gear 5 and the pin 58 shown in FIG.
6, a retaining ring 55, a sliding bearing 54, and a joint 51 urged by a compression spring 53 are integrated therein. The joint 51 is not separated from the rotation shaft 50 by the retaining ring 52. The integrated shaft 50 and the like are axially supported on the housing 1 by sliding bearings 57 at outer ends.

As shown in FIG. 2B, bearings 57 and 76 are provided on the respective axes of the rotating shafts 50 and 70 of the housing 1.
Holes 15 and 17 are provided for mounting the.

FIGS. 3 and 4 are cross-sectional views showing a state in which the above-described conventional drive unit is mounted on a main body housing 9.
The fixed shafts 13, 14, 16 of the housing 1
After passing through 4 and 6, the bosses 93, 94, 9
6 is fitted. On the other hand, the two rotating shafts 50 and 70 are provided with bearings 54 and 74 with respect to the housing 9 so that boss holes 95 and 97 of the housing.
The posture is determined in the horizontal direction by fitting into. After the shafts of the gear unit and the rotary shaft unit are fitted, as shown in FIG. 3, the housing 1 is screwed to the screw hole boss portion 91 of the housing 9 by screws 92.

The joints 51 and 71 provided on the main body side of the rotating shafts 50 and 70 are engaged with a flange joint 502 of the photosensitive unit 500 and a joint 702 of the developing unit 700, respectively. Both units 500 and 700 are configured to be mounted in a direction approaching from the far side of the housing 1 (in the direction of the arrow in the figure). In the figure, reference numeral 501 denotes a photosensitive drum, and reference numeral 701 denotes a developing roller.

FIG. 3B shows a flange joint 502.
FIG. 3C is a view of the joint 702 viewed from the rotation shaft 70 side. By adopting such a joint (shaft joint) configuration, even if the tips of the joint portions collide with each other at the time of mounting both the units 500 and 700, the compression springs 53 and 73 allow the unit to be mounted to a regular position without an excessive load. Is possible, and when the rotation of the motor starts, the joint on the drive unit side moves to the proper position (axial direction), and the drive rotation is transmitted.

The bearings at one shaft end are in contact with elastically bent terminals 80 and 85, and screws 81 and 86 are provided respectively.
To the housing 1 made of resin. Terminal 80
Is in contact with the rotating shaft 50 via a bearing 57, and the tip of the rotating shaft 50 elastically abuts on one end 504 of a leaf spring 503 in the photoreceptor in FIGS. 3 (A) and 3 (D). The other end 505 of the leaf spring 503 contacts the inner surface of the photoconductor 501 (element tube). On the other hand, by connecting one end of the terminal 80 to a ground potential portion (metal casing: not shown) of the machine, the raw tube of the photosensitive drum 501 is at the ground potential. Terminal 85
Is connected to a developing roller 701, is connected to a high voltage power supply unit (not shown), and is applied with a developing bias.

[0012]

When a shaft is formed of resin, the shaft is bent when a driving force for motor rotation is applied due to low rigidity, and the tip of the shaft becomes thin due to a draft at the time of molding. However, it was not possible to avoid the weakness of the material such that the play between the gear hole and the shaft became large. As a result, the meshing of the gears may be incomplete. In particular, if the meshing in the gear train for driving the photoconductor drum 501 is incomplete, the frequency of the backlash is about 30 to 300 Hz. Image density unevenness (writing pitch unevenness) sometimes occurred.

Further, since the rigidity of the flat portion of the housing 1 excluding the shaft portion cannot be made as high as that of the sheet metal part in many cases, the central portion of the housing (the portion on which the motor is mounted), which is far from the screwing portion, is a drum. As shown in the central portion of FIG. 1, the image is easily bent or vibrated, which causes a deterioration in image quality.

An object of the present invention is to reduce defects of a drive unit of an image forming apparatus having such a configuration and to improve image quality (improvement of gear rotation accuracy, prevention of vibration of a housing, etc.).

[0015]

According to a first aspect of the present invention, there is provided a drive unit for an image forming apparatus, wherein a gear, a rotating shaft, a bearing, and the like are integrally held to achieve the above object. In the drive unit of the image forming apparatus detachable from the housing of the main body, the drive unit housing and the shaft for the idler gear are integrally formed of resin, and a screw is passed through at least one of the resin shafts. It is characterized in that it is fastened to the housing of the image forming apparatus main body facing the unit housing.

According to a second aspect of the present invention, in order to achieve the above object, in the drive unit of the image forming apparatus according to the first aspect, the shaft fastened with the screw fixes the photosensitive member in the image forming apparatus main body. It is a shaft that supports one gear in a gear train to be driven.

According to a third aspect of the present invention, in order to achieve the above object, in the drive unit of the image forming apparatus according to the first aspect, the shaft fastened with the screw is a shaft that supports a gear adjacent to the motor gear. It is characterized by being.

According to a fourth aspect of the present invention, in order to achieve the above object, a gear, a rotating shaft, a bearing and the like are integrally held,
In a drive unit of an image forming apparatus detachable from a housing of an image forming apparatus main body, a drive unit housing is formed of resin, and at least one of shafts holding the gear is made of metal. I do.

According to a fifth aspect of the present invention, in order to achieve the above object, in the drive unit of the image forming apparatus according to the fourth aspect, the shaft made of metal has a photosensitive member in the main body of the image forming apparatus. It is characterized by one shaft in the gear train to be driven.

According to a sixth aspect of the present invention, in order to achieve the above object, in the drive unit of the image forming apparatus according to the fourth or fifth aspect, two or more shafts made of the metal are provided.
In addition, each shaft is integrally fixed to a metal plate.

According to a seventh aspect of the present invention, there is provided a drive unit for an image forming apparatus according to the fourth aspect, wherein the metal shaft and a rotary shaft bearing for driving the photosensitive member are provided. The fitting hole is provided in a metal plate.

According to an eighth aspect of the present invention, there is provided a drive unit for an image forming apparatus according to any one of the fourth to seventh aspects, wherein the metal shaft and the plate are grounded to a ground potential. It is characterized by becoming.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. In the following, portions common to the related art are denoted by the same reference numerals, and redundant description is omitted. FIG. 5 is a front view showing a gear layout of an embodiment of a drive unit of the image forming apparatus according to the present invention, and FIG. 6 is a side sectional view showing a gear mounting structure using a fixed shaft to a main body housing. As shown in the figure, in the present embodiment, a fixed shaft 103 corresponding to the fixed shaft 13 of the conventional example in FIG.
4 secures the screw to the opposing boss 101.
The rib 102 has a stopper function for preventing the reduction gear 3 from shifting toward the housing 9. In FIG. 6, the inner diameter of the fixed shaft 103 is set to a size that allows the head of the screw 104 to pass through. However, the inner diameter of the fixed shaft 103 is set to be slightly larger than the outer diameter of the screw portion of the screw 104, and instead, the screw length is changed. May be longer. However, when the thickness is as shown in FIG. 6, the rigidity of the fixed shaft 103 is increased, and the falling due to the force received from the gear shaft 20 or the reduction gear 4 of the adjacent motor 2 can be reduced.

In FIG. 5, reference numeral 400 denotes a fixing roller gear, 4
01 is a discharge roller pulley, 402 is a registration roller clutch gear, 403 is a first stage paper feed roller clutch gear, 404 is a second stage paper feed roller clutch gear, 40
5 is a manual feed roller clutch gear, 406 is a manual feed roller gear, 407 is a relay roller driving pulley, 408 is a relay roller clutch gear, and 409 is a relay roller second pulley.

FIG. 7 is a side sectional view showing a gear mounting structure with a fixed shaft to a main body housing in another embodiment of the drive unit of the image forming apparatus according to the present invention. In this embodiment, fixed shafts 110 and 113 corresponding to the fixed shafts 13 and 14 of the conventional example in FIG. The plate 109 is made of metal, and the fixed shafts 110, 1
Since 13 is fixed by caulking at an accurate position, strength against falling is strong. Further, since the fixed shafts 110 and 113 can be manufactured by machining a metal round bar, the dimensional accuracy can be extremely increased. Plate 109, fixed shaft 110,
Screw 113 (not shown) may be used to fix 113 to housing 1, but the distance between the two fixed shafts and the distance X between holes 112 and 115 into which they are inserted are accurately set. By properly setting the shape and dimensions of the holes, light press-fitting can be performed without using screws. The ends of the shafts 111 and 114 are fitted to the opposing bosses 93 and 94, so that both shafts are fixed at both ends, so-called a two-sided support to prevent the shafts from falling down.

FIG. 8 is a side sectional view showing a gear mounting structure with a fixed shaft to a main body housing in another embodiment of the drive unit of the image forming apparatus according to the present invention. In this embodiment, fixed shafts 113 corresponding to the fixed shafts 13 and 14 of the conventional example in FIG. Board 120
Is provided with a hole 121 and a bearing 122 is fitted therein. The bearing 122 corresponds to the bearing 57 of the conventional example in FIG. 4 and receives the rotating shaft 50 that holds the gear 5. Further, one end of the bearing 122 is fitted into the hole 123 of the housing. Here, since the plate 120 and the bearing 122 are made of metal, the rotating shaft 50 has the same potential as the plate 120. Further, the tip of the rotating shaft 50 is elastically in contact with one end 504 of a leaf spring 503 in the photoconductor 501 (not shown in this figure; see FIG. 3). When the other end 505 of the leaf spring 503 hits the inner surface of the photoconductor 501 (primary tube), the potential of the photoconductor primary tube and the potential of the plate 120 become equal, and the potential of the plate 120 is set to the ground potential. The potential goes to ground.

[0027]

As described above, in the drive unit of the image forming apparatus according to the first aspect of the present invention, at least one of the resin shafts is screwed to the housing opposite to the housing. Thereby, the housing and the housing are integrated, the rigidity of the entire machine is improved, and the effect that the gear meshing accuracy due to the twist of the shaft and the like can be prevented from being reduced can be obtained.

In the drive unit of the image forming apparatus according to the second aspect of the present invention, as described above, the screw shaft is used as one shaft in the gear train for driving the photoreceptor. In addition, the effect of improving the rotation accuracy of the photoconductor can be obtained.

The drive unit of the image forming apparatus according to the third aspect of the present invention, as described above, uses the screwed shaft as the shaft of the gear adjacent to the motor gear. The vicinity of the unstopped motor (near the center of the housing) is integrated with the housing, so that the rigidity of mounting the housing is improved and the amplitude of vibration transmitted to the housing can be reduced.

The drive unit of the image forming apparatus according to the fourth aspect of the present invention has at least one of the shafts for holding the gears made of metal as described above. And the effect of improving the rotation accuracy of the shaft is obtained.

In the drive unit of the image forming apparatus according to the fifth aspect, as described above, the metal shaft is used as one shaft in the gear train for driving the photoreceptor. In addition, the effect of improving the rotation accuracy of the photoconductor can be obtained.

As described above, in the drive unit of the image forming apparatus according to the present invention, two or more metal shafts are provided and each shaft is integrally fixed to a metal plate. Thereby, in addition to the above-mentioned common effects, the rotational accuracy of the gear train is further improved, and the mounting posture of the metal plate to the housing is regulated by the two shafts, so that the assembling workability is improved while improving the dimensional accuracy. The effect is obtained.

In the drive unit of the image forming apparatus according to the seventh aspect, as described above, the metal shaft and the bearing fitting hole of the rotary shaft for driving the photosensitive member are provided integrally with the metal plate. As a result, in addition to the above common effects, the mounting posture of the metal plate to the housing is regulated by one shaft and a bearing,
The effect of improving the assembly workability while improving the dimensional accuracy is obtained.

In the drive unit of the image forming apparatus according to the eighth aspect, as described above, the shaft and the plate are grounded to the ground potential, so that the potential of the photosensitive drum is lowered to the ground via the metal plate. This makes it possible to obtain an effect that an expensive component such as a leaf spring or a ground wire (harness) is not required and an inexpensive component can be formed.

[Brief description of the drawings]

FIG. 1 is a front view showing a gear train near a motor in a conventional drive unit.

FIG. 2 is a right side sectional view (A) of the conventional drive unit of FIG. 1 and a right side sectional view (B) of a housing of the drive unit.

FIGS. 3A and 3B are a cross-sectional view showing a state in which the drive unit is mounted on a main body housing, a front cross-sectional view of a flange joint viewed from a rotary shaft side, and a front cross-sectional view of the joint viewed from a rotary shaft side. (C), It is a perspective view (D) of the same leaf spring.

FIG. 4 is a detailed sectional view developed from the state of FIG. 3 with respect to the meshing state of the gears.

FIG. 5 is a front view showing a gear layout of an embodiment of the drive unit of the image forming apparatus according to the present invention.

FIG. 6 is a side cross-sectional view showing a gear mounting structure using a fixed shaft to a main body housing.

FIG. 7 is a side cross-sectional view showing a gear mounting structure with a fixed shaft to a main body housing in another embodiment of the drive unit of the image forming apparatus according to the present invention.

FIG. 8 is a side cross-sectional view showing a gear mounting structure using a fixed shaft to a main body housing in another embodiment of the drive unit of the image forming apparatus according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 housing 2 motor 3, 4. 8 reduction gear 5, 6, 7 gear 9 body housing 11, 12 boss 13, 14, 16 fixed shaft 15, 17 hole 20 motor gear shaft 50, 70 rotation shaft 51, 71 joint 53, 73 compression spring 54 sliding bearing 55, 56, 72, 75 retaining ring 57, 76 sliding bearing 58 pin 74 ball bearing 78 pin 80, 85 terminal 81, 86, 92 screw 91, 93, 94, 96 boss part 95, 97 boss Hole 101 Boss 102 Rib 103, 113 Fixed shaft 104 Screw 107, 108 Idler gear 109, 120 Plate 112, 115, 121 Hole 122 Bearing 123 Housing hole 400 Fixing roller gear 500 Photoconductor unit 501 Photoconductor drum 502 Flange joint 503 Plate spring 700 Developing unit 70 Developing roller 702 joint

Claims (8)

[Claims] 1. A drive unit of an image forming apparatus which integrally holds a gear, a rotating shaft, a bearing and the like and is detachable from a housing of an image forming apparatus main body, wherein a drive unit housing and a shaft for an idler gear are made of resin. A drive unit for driving the image forming apparatus, wherein the drive unit housing is integrally formed, and a screw is passed through at least one of the resin shafts and fastened to a housing of the image forming apparatus main body facing the drive unit housing. unit. 2. A driving unit for an image forming apparatus according to claim 1, wherein the shaft fastened by the screw is a shaft for supporting one gear in a gear train for driving a photoconductor in the image forming apparatus main body. A driving unit for an image forming apparatus, comprising: 3. The drive unit for an image forming apparatus according to claim 1, wherein the shaft fastened with the screw is a shaft that supports a gear adjacent to a motor gear. 4. A drive unit of an image forming apparatus which integrally holds a gear, a rotating shaft, a bearing and the like and is detachable from a housing of the image forming apparatus main body. A drive unit for an image forming apparatus, wherein at least one of the shafts holding the gear is made of metal. 5. The drive unit for an image forming apparatus according to claim 4, wherein the shaft made of metal is one shaft in a gear train for driving a photoconductor in the image forming apparatus main body. Drive unit of the image forming apparatus. 6. A driving unit for an image forming apparatus according to claim 4, wherein two or more shafts made of metal are provided, and each shaft is integrally fixed to a metal plate. Drive unit of the image forming apparatus. 7. The driving unit of the image forming apparatus according to claim 4, wherein the metal shaft and a bearing fitting hole of a rotating shaft for driving the photoconductor are provided in a metal plate. Drive unit of the image forming apparatus. 8. A drive unit for an image forming apparatus according to claim 4, wherein said metal shaft and said plate are grounded to a ground potential.