JP5230479B2 - Drive transmission device and image forming apparatus - Google Patents

Description

  The present invention relates to a drive transmission device including a shaft and a rotating body through which a driving force of a drive motor is transmitted, and an image forming apparatus such as an electrophotographic color electrophotographic printer including the drive transmission device. .

  Conventionally, for example, as described in Patent Document 1 below, a gear that engages with a groove formed in a shaft having a D-cut portion whose cross section is cut into a D shape, and rotates integrally with the shaft, etc. As a means for preventing the rotating body from coming off in the axial direction, in particular, when the rotating body is a resin molded product, it is common to engage a flexible protrusion such as a claw integrally molded with the rotating body with the groove. Has been done.

Japanese Utility Model Publication No. 06-51557

  However, it is necessary to increase the strength of the claw integrally formed with the rotating body, which is a resin molded product, so that the rotating body does not come off the shaft due to an impact during product transportation. On the other hand, when the strength of the claw of the rotating body is increased, the bending of the claw exceeds the allowable stress when the shaft is inserted into the through hole provided in the rotating body. For this reason, there is a problem that the shaft cannot be repeatedly inserted into and removed from the through hole of the rotating body.

  Further, when a retaining ring such as an E ring is used as a means for preventing the rotating body from coming off the shaft in the axial direction, an E ring formed separately from the rotating body is required. When this E-ring is lost due to loss or the like, the same type of E-ring must be searched from a warehouse or the like that is a storage place for permanent items and maintained by attaching a new E-ring to the shaft. Therefore, it is difficult to immediately recover the retaining member of the rotating body. Accordingly, the E-ring formed separately from the rotating body has a problem in terms of maintenance and complicated storage management of regular items.

  In order to solve such a problem, the present invention focuses on a rotating body structure such as a gear that can form the same type of E-ring on the gear body in the gear including the gear body and the tooth portion.

  SUMMARY An advantage of some aspects of the invention is that it provides a drive transmission device using a hollow hole formed in a resin molded product or the like and an image forming apparatus including such a drive transmission device.

The drive transmission device of the present invention has a rotatable shaft having a groove portion in the radial direction, a through-hole through which the shaft can pass, and a gear body that is inserted through the through-hole and is rotatable about the shaft. And a toothed portion formed on the outer periphery of the gear body, and a retaining ring for preventing the shaft from coming off from the gear .

The gear includes a tooth portion formed on the outer periphery, a through hole formed in the center through which the shaft is inserted, a plurality of hollow holes formed around the through hole, and the vicinity of the through hole. And a protrusion protruding in the axial direction from the side surface. The retaining ring is separable from the runner, a runner formed inside at least one of the plurality of lightening holes, a plurality of engaging portions engageable with the groove, and the runner. A flexible arm portion that connects the plurality of engaging portions, and the thickness of the engaging portion is larger than the thickness of the arm portion, and the runner and the retaining ring are the gears. And are integrally formed. Further, the retaining ring is configured to be separated from the runner so that the plurality of engaging portions can be engaged with the groove portions and the projecting portions .

According to the drive transmission device of the present invention, the retaining ring for preventing the shaft from coming off from the gear has the engaging portion that can be engaged with the groove portion of the shaft, and is integrally formed so as to be removable from the gear body. . For this reason, even if the retaining ring is eliminated, it is possible to remove the equivalent retaining ring from the gear body and immediately attach it to the shaft.
The gear is provided in the vicinity of a tooth portion formed on the outer periphery, a through hole formed at the center and through which the shaft is inserted, a plurality of hollow holes formed around the through hole, and the through hole. And a protrusion protruding in the axial direction from the side surface. Further, the retaining ring is separable from the runner formed inside at least one of the plurality of lightening holes, a plurality of engaging portions engageable with the groove, and separable from the runner. And a flexible arm portion that connects the plurality of engaging portions, and the engaging portion has a thickness larger than that of the arm portion and is integrally formed with the gear via the runner. Separated from the runner, the plurality of engaging portions can be engaged with the groove portions and the projecting portions. Therefore, unless the retaining ring is consciously peeled off from the gear body by hand, there is no fear that it will come off during rotation of the shaft.

FIG. 1 is a perspective view schematically illustrating an improved image forming unit up / down mechanism according to the first embodiment. FIG. 2 is a configuration diagram illustrating an outline of the image forming apparatus including the drive transmission device according to the first exemplary embodiment of the present invention. FIG. 3 is a perspective view of the image forming unit up / down mechanism according to the first exemplary embodiment. 4 is a cross-sectional view of FIG. FIG. 5A is a side view illustrating an outline of the operation of the image forming unit up / down mechanism of FIG. FIG. 5B is a side view illustrating an outline of another operation of the image forming unit up / down mechanism of FIG. FIG. 6A is a perspective view illustrating the inner side surface of the up / down gear of the improved image forming unit up / down mechanism according to the first embodiment. FIG. 6B is a perspective view of the outer surface of FIG. 6A. FIG. 7A is a perspective view illustrating the inner surface of the up / down gear of the image forming unit up / down mechanism according to the second embodiment. FIG. 7B is a perspective view of the front side surface of the E-shaped retaining ring 410 ′ of FIG. 7A. FIG. 7C is a perspective view of the back side surface of FIG. FIG. 8 is a perspective view illustrating an outline of an image forming unit up / down mechanism according to the second embodiment.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Image Forming Apparatus of Example 1)
FIG. 2 is a configuration diagram illustrating an outline of the image forming apparatus including the drive transmission device according to the first exemplary embodiment of the present invention.

  The image forming apparatus 1 is, for example, an electrophotographic color electrophotographic printer, and corresponds to toner that is a developer for each color of black (K), yellow (Y), magenta (M), and cyan (C). This is a so-called tandem type image forming apparatus in which the image forming units 2 (= 2K, 2Y, 2M, 2C) are arranged.

  The image forming units 2 are configured in the same manner, and are arranged in the order of the image forming units 2K, 2Y, 2M, and 2C in the arrow direction A indicating the conveyance direction of the recording paper P. In the following description, the downstream side in the conveyance direction of the recording paper P on the left side in FIG. 2 is referred to as the R direction (rear direction), and the upstream side in the conveyance direction of the recording paper P on the right side in FIG. (Forward).

  Each image forming unit 2 includes a photosensitive drum 20 that is an image carrier that can rotate clockwise B. The photosensitive drum 20 is rotationally driven by a driving unit (for example, a photosensitive drum motor (not shown)) that operates the image forming apparatus. Around the photosensitive drum 20, a charging roller 21, an LED head 22, and a developing unit 23 are arranged. Under the photosensitive drum 20, a transfer roller 24 is disposed so as to sandwich the recording paper P between the photosensitive drum 20.

  For example, in the case of the black image forming unit 2K, the developing unit 23 includes a k toner storage container 23c that stores K toner. In the k toner container 23c, a developing roller 23a as a developer carrying member and a toner supply roller 23b for supplying the developer to the developing roller 23a side are provided.

  The charging roller 21 uniformly charges the surface of the photosensitive drum 20. The LED head 22 selectively exposes the uniformly charged photosensitive layer of the photosensitive drum 20 according to image information. In the photosensitive layer of the photosensitive drum 20, the charged portion is removed from the exposed portion, and the charged portion is left in the unexposed portion, thereby forming an electrostatic latent image. The developing unit 23 causes toner to adhere to the electrostatic latent image formed on the photosensitive drum 20 by the developing roller 23a to form a toner image. The transfer roller 24 transfers the toner image formed on the surface of the photosensitive drum 20 to the recording paper P by applying a charge having a polarity opposite to that of the toner from the back surface of the recording paper P.

  The conveyance belt V that conveys the recording paper P that is a recording medium is a so-called endless belt, and is stretched between a pair of rollers 25 and 26. The rollers 25 and 26 are provided so as to sandwich the transfer rollers 24 of the image forming units 2. The rollers 25 and 26 are arranged such that the axial direction thereof coincides with the width direction of the transport belt V. Among the rollers 25 and 26, the roller 26 is a conveyance belt drive roller 25 that is rotationally driven by a conveyance belt drive motor (not shown) that is a drive unit. The conveyor belt V moves in the arrow direction A by the rotation of the conveyor belt drive roller.

  As shown in FIG. 2, the fixing unit 16 is arranged in the R direction of the transport belt driving roller 25. The recording paper P is pressed and heated by the fixing unit 16 to fix the toner image. The fixing unit 16 is a fixing roller 16a having a built-in heater, a pressure roller 16b that sandwiches the recording paper P between the fixing roller 16a, and a driving unit that supplies driving force for rotating the fixing roller 16a (not shown). It has a fixing motor and a mechanism for transmitting the driving force of the fixing motor to the fixing roller 16a, for example, a gear train (not shown).

  Two sets of discharge guide roller pairs 17 and 18 for guiding the recording sheet P to the recording sheet discharging section 19 disposed at the upper part of each image forming section 2 are disposed in the R direction of the fixing unit 16.

  A paper feeding unit 10 that receives and supplies the recording paper P is disposed below each image forming unit 2. The paper feed unit 10 includes a small-diameter auxiliary roller 12 that feeds the recording paper P out of the paper feed unit 10 and a large-diameter paper feed roller 13. The paper feed roller 13 is rotationally driven by a paper feed motor (not shown) that is a drive unit. An inclined plate 11 for pressing the leading edge of the recording paper P against the auxiliary roller 12 and the paper feeding roller 13 is disposed adjacent to the auxiliary roller 12 of the paper feeding unit 10.

  Two pairs of conveyance rollers 14 and 15 for conveying the recording paper P to the black image forming unit 2K are arranged on a conveyance path from the paper supply unit 10 to the image forming unit 2K. Each of the conveyance roller pairs 14 and 15 is also referred to as a registration roller pair, and has a role of conveying the recording paper P fed from the paper feeding unit 10 to the conveyance belt V and also records fed from the paper feeding unit 10. When the sheet P is fed out at an inclination, the skew of the recording sheet P is corrected by the one registration roller pair 14 and sent to the other registration roller pair 15.

  As described in the image forming apparatus, the drive transmission apparatus including the shaft through which the driving force of various driving units is transmitted and the roller that is a rotating body is used in each image forming process of the image forming apparatus. .

(Operation of Image Forming Unit Up / Down Mechanism of Example 1)
FIG. 3 shows an image forming unit up / down that separates the image forming units 2Y, 2M, and 2C from the conveyor belt V in order to prevent consumption of toner of each color in the image forming units 2Y, 2M, and 2C other than black that are not used during monochrome printing. It is a perspective view of a mechanism.

  The drive transmission apparatus according to Embodiment 1 of the present invention is used as a drive unit that operates the image forming unit up / down mechanism 30 shown in FIG.

4 is a cross-sectional view of the main components of the image forming unit up / down mechanism 30 shown in FIG.
In the image forming unit up / down mechanism 30, the up / down gear 31 has a two-stage gear configuration of a large gear 31a and a small gear 31b. As shown in FIGS. 3 and 4, the drive gear 32 a of the up / down drive motor 32 meshes with the large gear 31 a of the up / down gear 31 to drive the up / down gear 31. The small gear 31 b of the up / down gear 31 is engaged with a rack 33 a formed integrally with the right slide arm 33 and drives the right slide arm 33.

  The rotating shaft 34 is fitted in a through hole 31 c having a D cut portion provided in the up / down gear 31. The retaining member 40 made of a resin material integrally formed with the up / down gear 31 has a flexible engaging portion 40a that can be engaged with the groove portion 34a (see FIG. 4) of the rotating shaft 34. Therefore, the rotation shaft 34 can be rotated integrally with the up / down gear 31 without coming out of the up / down gear 31. The components arranged on the right side of the image forming unit up / down mechanism 30 are assembled to the right frame 35 shown in FIG. The right end portion of the rotating shaft 34 is also supported by a bearing 35a attached to the right frame 35.

  On the other hand, a separate up / down gear 31 'arranged on the left side is also fixed to the left end portion of the rotating shaft 34 in the same manner. The small gear 31 ′ b of the up / down gear 31 ′ meshes with a rack 36 a formed integrally with the left slide arm 36 and drives the left slide arm 36 as the rotating shaft 34 rotates.

  The right slide arm 33 and the left slide arm 36 are assembled so as to be driven in the same phase. The shutter portion 36b formed integrally with the left slide arm 36 controls the up / down drive motor 32 using a timing at which the photo interrupter 37 is shut off as a trigger. The components arranged on the left side of the image forming unit up / down mechanism 30 are assembled to the left frame 38 shown in FIG. The left end portion of the rotary shaft 34 is also supported by a bearing 38a attached to the left frame 38.

  FIG. 5A is a side view illustrating the operation of the image forming unit up / down mechanism 30 in the color printing mode. FIG. 5B is a side view illustrating the operation of the image forming unit up / down mechanism 30 in the monochrome printing mode.

  FIG. 5A shows a state in which the photosensitive drum shafts 2Ya, 2Ma, and 2Ca corresponding to the image forming units 2Y, 2M, and 2C are slightly separated from the right slide arm 33 (or the left slide arm 36). ing. On the other hand, FIG. 5B illustrates the right slide arm 33 (or the left slide arm 36) in which the photosensitive drum shafts 2Ya, 2Ma, and 2Ca corresponding to the toner image forming portions 2Y, 2M, and 2C of the respective colors except black are moved. ) Shows a state of being lifted upward.

(Configuration of Improved Image Forming Unit Up / Down Mechanism of Example 1)
Next, an improved image forming unit up / down mechanism including a drive transmission device improved from the drive transmission device according to the first embodiment of the present invention will be described.

  FIG. 6A is a perspective view showing an inner surface of the up / down gear 310 in the improved image forming unit up / down mechanism including the improved drive transmission device.

FIG. 6B is a perspective view of the outer surface of the up / down gear 310.
The up / down gear 310 includes a gear main body 310a and a tooth portion 310c formed on the outer periphery of the main body 310a. The gear main body 310a has a through hole 311 in the center and a plurality of circular hollow holes 312 formed in the vicinity of the periphery. The through hole 311 has a cross section cut into a D shape as shown in FIG. The lightening hole 312 is provided in the vicinity of the peripheral portion of the gear body 310a in order to reduce the weight of the gear part and to improve the gear accuracy.

  An E-shaped retaining ring 410 is integrally formed in the gear body 310 a through the runner 420 in the lightening hole 312. That is, the E-shaped retaining ring 410 is connected to the gear body 310 a of the up / down gear 310 by the plurality of runners 420. For this reason, the E-shaped retaining ring 410 is not likely to come off during the rotation of the up / down gear 310 unless it is consciously peeled off from the gear body 310a.

  When assembling the up / down gear 310 to the rotary shaft 34, before or after the rotary shaft 34 is inserted into the through hole 311 of the up / down gear 310, an E-shaped retaining ring 410 formed in one of the plurality of lightening holes 312 is provided. It is separated from the gear body 310a and attached to the rotary shaft 34. Each engagement portion of the E-shaped retaining ring 410 is engaged with a groove portion (not shown) formed in the rotary shaft 34.

  The gear body 310a, which is a rotating body, has a protrusion 313 that protrudes in the axial direction from the surface of the gear body 310a immediately below the cut portion 311a of the D-shaped through hole 311. When the E-shaped retaining ring 410 is attached to the rotating shaft 34, the pair of engaging portions 410a and 410b formed at both ends of the E-shaped retaining ring 410 further engages with the protruding portion 313 (see FIG. 1). Thereby, the rotation of the E-shaped retaining ring 410 is prevented.

  In the first embodiment of the improved drive transmission device, the E-type retaining ring 410 is formed in two of the six hollow holes 312 formed in the gear body 310a of the up / down gear 310. However, the number of E-shaped retaining rings 410 can be increased as necessary.

(Operation of Improved Image Forming Unit Up / Down Mechanism of Example 1)
FIG. 1 is a perspective view schematically illustrating a state in which an E-shaped retaining ring 410 in the improved drive transmission device of the first embodiment is separated from an up / down gear 310 and attached to an image forming unit up / down mechanism 300.

  The basic operation of the image forming unit up / down mechanism 300 including the improved drive transmission device of the first embodiment is the same as the operation of the image forming unit up / down mechanism 30 including the drive transmission device of the first embodiment.

(Modification of Improved Image Forming Unit of Embodiment 1)
In the first embodiment, the retaining member is described based on the E-shaped retaining ring made of a resin material. However, the retaining member may be a retaining ring made of a metal material. The retaining ring may be a C-shaped retaining ring.

(Effect of the improved drive transmission device of Example 1)
According to the first embodiment, the up / down gear 310 is prevented from coming off by the removable E-shaped retaining ring 410 formed integrally with the gear main body 310a. What is necessary is just to isolate | separate from the gear main body 310a, and to use for the removal of the rotation shaft 34. Therefore, the E-shaped retaining ring 410 does not need to be stored and managed as a separate part of the image forming unit up / down mechanism 300.

  Since a plurality of E-shaped retaining rings 410 are integrally formed with the gear body 310a, for example, when disassembling and reassembling for maintenance of the image forming unit up / down mechanism 300, the E-shaped retaining ring in use. Even if 410 is lost, the same thing can be separated from the gear body 310a and used. Therefore, the structure of the up / down gear 310 in which a plurality of E-shaped retaining rings are integrally formed is convenient for maintenance.

  Further, since the integrally formed E-shaped retaining ring 410 is formed in the fillet hole 312 that is provided evenly in the vicinity of the periphery of the gear body 310a, the accuracy of the up / down gear 310 is not adversely affected. .

(Comparative example of Example 1)
In the case of a conventional gear retaining means used in the drive transmission device of the image forming apparatus 1, that is, an engaging portion such as a claw integrally formed with the gear, if an impact is received from the side surface of the drive transmission device during transportation, As a result of the impact value proportional to the weight and the deformation of the left and right frames 35 and 38 shown in FIG. On the other hand, when the strength of the engaging portion was increased, the bending of the engaging portion exceeded the allowable stress, so that the strength of the engaging portion was lowered and the shaft could not be repeatedly inserted and removed.

  However, in the first embodiment, the E-shaped retaining ring 410 formed integrally with the gear is used for retaining the shaft. Thereby, even if it receives an impact from the side of the drive transmission device, there is no structural element that the engaging portion bends, and the shaft does not come out of the gear.

(Configuration of Drive Transmission Device of Example 2)
The drive transmission apparatus in Example 2 of this invention is demonstrated. Note that the basic configuration of the drive transmission device according to the second embodiment is the same as that of the improved drive transmission device according to the first embodiment, and therefore different components from the first embodiment will be described.

  FIG. 7A is a perspective view illustrating the inner side surface of the up / down gear 310 in the image forming unit up / down mechanism including the drive transmission device according to the second embodiment.

  FIG. 7B is a perspective view of the front side surface of the E-shaped retaining ring 410 ′ integrally formed with the up / down gear 310 according to the second embodiment.

  FIG. 7C is a perspective view of the back side surface of the E-shaped retaining ring 410 ′ integrally formed with the up / down gear 310 according to the second embodiment.

  FIG. 8 is a perspective view schematically showing a state in which the E-shaped retaining ring 410 ′ is attached to the image forming unit up / down mechanism 300 in the drive transmission device according to the second embodiment.

  An E-shaped retaining ring 410 ′ shown in FIGS. 7-2 and 7-3 is integrally formed with the up / down gear 310 via the runner 420 in the lightening hole 312 formed in the gear body 310 a of the up / down gear 310. Has been.

  The E-shaped retaining ring 410 ′ has a pair of engaging claw portions 410′a and 410′b that project inwardly and opposite to both ends of an arm portion 410′d formed in a C-ring shape, and an arm portion 410. It has a third engaging claw portion 410′c protruding inwardly at the center of “d”. It has an engaging claw part which protrudes inward in the central part of an arm part.

  In the E-type retaining ring 410 ′ of the second embodiment, the plate thickness of the three engaging claws 410′a, 410′b, 410′c that engage with a groove portion (not shown) of the rotary shaft 34 is the arm portion 410 ′. It is formed larger than the plate thickness d.

(Operation of Image Forming Unit Up / Down Mechanism of Example 2)
FIG. 8 shows a state in which the up / down gear 310 is mounted and fixed to the rotating shaft 34 using the E-shaped retaining ring 410 ′ separated from the up / down gear 310 in the drive transmission device of the second embodiment.

  In the image forming unit up / down mechanism of the first embodiment, the method for preventing the rotation shaft 34 from being detached by the E-shaped retaining ring 410 made of a resin material integrally formed with the up / down gear 310 has been described. Retaining rings made of resin material have lower strength compared to retaining rings made of metal material, and when molded with the same plate thickness as retaining rings made of metal material, if the side impact received during product transportation is extremely large, shear stress May be destroyed.

  On the other hand, when the retaining ring made of resin material is made thicker, the retaining ring is too rigid when the retaining ring is engaged with the groove of the rotating shaft 34, and both ends of the retaining ring are sufficiently I can't open it. As a result, the retaining ring is difficult to engage with the groove portion of the rotating shaft 34, causing a problem in assembly work.

  Therefore, as shown in FIGS. 7-2 and 7-3, in the second embodiment, the plate thickness of the two arm portions 410 ′ of the E-shaped retaining ring is such that the retaining ring is engaged with the groove of the rotating shaft 34. At this time, the plate thickness that does not deteriorate the assembling workability was maintained so that both end portions of the retaining ring can be opened by appropriately bending the two arm portions 410. On the other hand, the three engaging claws that engage with the grooves of the rotating shaft 34 ensure the necessary plate thickness in order to withstand the maximum shear stress predicted by the calculation.

  The basic operation of the image forming apparatus including the drive transmission device according to the second embodiment has been described with reference to the image forming apparatus according to the first embodiment, and a description thereof will be omitted.

(Effect of the dynamic transmission device of the second embodiment)
According to the second embodiment, in addition to the effect of the motion transmission device of the first embodiment described above, even the retaining ring made of a resin material integrally formed with the gear body engages with the groove portion of the rotating shaft. By increasing the thickness of only the claw portion, the required strength can be ensured without deteriorating the workability when the E-shaped retaining ring is assembled to the rotating shaft.

(Other variations of Examples 1 and 2)
In the first and second embodiments, the drive transmission device is applied to a drive gear used by being engaged with a rotary shaft having a D-cut portion of a color electrophotographic printer. However, the drive gear is rotatable with respect to the shaft. It can also be applied to. Further, the present invention can be applied to a rotating body other than a gear such as a cam or a lever regardless of the engagement condition with respect to the shaft. Further, the present invention can also be applied to a rotary body used in an image forming apparatus such as a facsimile machine, a copying machine, and a multi-function machine (MFP) having a combination thereof.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 2 Developing unit 30, 300 Image forming part up / down mechanism 31 Up / down gear transfer unit 31c Through hole 34a Groove part 6 Fixing unit 21 Photosensitive drum 22 Charging roller 23 Cleaning blade 24 Developing roller 25 Developing blade 62 Fixing roller 63 Pressure roller 64 Heater 65 Thermistor for fixing

Claims (3)

A rotatable shaft having a groove in the radial direction;
A tooth portion formed on the outer periphery, a through hole formed in the center and through which the shaft is inserted, a plurality of hollow holes formed around the through hole, and a shaft from a side surface provided in the vicinity of the through hole A gear having a protrusion protruding in the direction;
A runner formed inside at least one of the plurality of lightening holes;
A plurality of engaging portions engageable with the groove portion, and a flexible arm portion that is detachably connected to the runner and connects the plurality of engaging portions; A retaining ring having a thickness greater than that of the arm,
The runner and the retaining ring are integrally formed with the gear,
The drive ring device is characterized in that the retaining ring is separated from the runner, and the plurality of engaging portions can be engaged with the groove portions and the projecting portions . The axis is a rotating shaft;
The gear meshes with a drive gear of an up / down drive motor, and has a tooth portion, a through hole formed in the center through which the rotating shaft is inserted, and a plurality of lightenings formed around the through hole. 2. The image forming unit up / down mechanism having a drive transmission device according to claim 1, wherein the image forming unit is an up / down gear having a gear body having a hole. In an image forming apparatus that forms an image on a recording medium by a predetermined image forming process,
A plurality of drive units for operating the image forming apparatus;
The image forming apparatus according to claim 1, wherein at least one drive unit of the drive units includes the drive transmission device according to claim 1.

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