JP2007139005A - Drive transmission device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive transmission device having simple and compact construction for developing nonloosing function for a screw member, and to provide an image forming device having the same. <P>SOLUTION: A drive side coupling 57 to be joined to a coupling on the side of a photosensitive drum, not illustrated, is inserted through a drive shaft 60 and mounted thereon with a drive side coupling fastening screw 63 threaded to the insertion end of the drive shaft 60. A tolerance is set so that the insertion side end face of the drive shaft 60 is a little protruded from a thrust supporting face 57b of the drive side coupling 57 at a position where a parallel pin 66 passing through the drive shaft 60 abuts on a pin groove 57c of the drive side coupling 57. During fastening the drive side coupling fastening screw 63, a clearance g is formed between the thrust supporting face 57b and the opposite face (the seat face) of a seat portion 60a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive transmission device for transmitting a driving force, and an image forming apparatus such as a copying machine, a printer, a facsimile, and a plotter having the drive transmission device.

In general, this type of drive transmission device has a configuration in which a drive force is transmitted from the drive shaft to the driven shaft by attaching couplings to the drive shaft and the driven shaft, respectively, and coupling the couplings. .
Patent Document 1 discloses a configuration in which a photosensitive drum is driven by a motor of a copying machine body via a drive transmission device.
On the driven side of the drive transmission device, the driven shaft is inserted into the driven side coupling, and a screw member having a seat portion larger than the diameter of the insertion hole is screwed into the insertion end portion of the driven shaft. The drive side coupling is attached so that it can be prevented from coming off. The driven side coupling has an engaging pin that engages with the driving side coupling and is slidable on the driven shaft, and is biased toward the driving side coupling by a spring. Has been.
In a state where the driving side coupling and the driven side coupling are engaged, a certain clearance is formed between the seat portion of the screw member and the thrust receiving surface of the driven side coupling opposed thereto. It has become. Since the seat portion of the screw member does not come into contact with the thrust receiving surface, it is possible to prevent problems due to looseness of the screw member in the usage mode in which the forward rotation and the reverse rotation of the drive shaft exist.

JP-A-4-14057 JP 2003-91208 A JP 2002-70881 A JP 2003-28241 A

In the configuration described in Patent Document 1, the driven-side coupling is slidable by the stroke of the spring, so that the bulk of the parts before the engagement is large, and the biasing force of the spring is resisted prior to the engagement. Therefore, there is a problem from the viewpoint of compactness and usability.
In addition, the configuration using springs has a problem that the assembly is troublesome and the cost of parts is high.

  SUMMARY OF THE INVENTION The main object of the present invention is to provide a drive transmission device and an image forming apparatus having the drive transmission device capable of obtaining a screw member loosening prevention function with a simple and compact configuration.

  In order to achieve the above object, according to the first aspect of the present invention, a shaft is inserted into at least one coupling, and a screw member having a seat portion larger than the diameter of the insertion hole is screwed into the insertion end portion of the shaft. Then, in the drive transmission device having a configuration in which the coupling is attached so as not to be detached, a clearance is provided between the seat portion of the screw member and the thrust receiving surface of the coupling opposed to the seat. In this range, the shaft and the coupling are assembled so as to be slidable in the axial direction.

According to a second aspect of the present invention, a shaft is inserted into at least one of the couplings, and a screw member having a seat portion larger than the diameter of the insertion hole is screwed into the insertion end portion of the shaft so that the coupling is removed. In the drive transmission device having a configuration that can be fixed, the contact area between the seat portion of the screw member and the thrust receiving surface of the coupling facing the seat portion is reduced.
According to a third aspect of the present invention, in the drive transmission device according to the second aspect, a ring-shaped convex portion is formed on the thrust receiving surface.
According to a fourth aspect of the present invention, in the drive transmission device according to the second aspect, a radial convex portion is formed on the thrust receiving surface.
According to a fifth aspect of the present invention, in the drive transmission device according to the second aspect, a cylindrical convex portion is formed on the thrust receiving surface.

According to a sixth aspect of the present invention, in the drive transmission device according to the second aspect of the present invention, radial thrusts that are asymmetric in the rotational direction of the shaft are formed on the thrust receiving surface.
According to a seventh aspect of the present invention, in the drive transmission device according to the fourth or sixth aspect, a taper is formed on the convex portion so that the screw member is easily bent in the tightening direction and the screw member is loosened. It is characterized by being difficult to bend.
According to an eighth aspect of the present invention, in the drive transmission device according to any one of the second to seventh aspects, the axial cross section of the convex portion on the side in contact with the seat portion is curved. And
According to a ninth aspect of the present invention, in the drive transmission device according to any one of the second to eighth aspects, a coating is applied to at least a portion of the thrust receiving surface that contacts the seat portion. .
According to a tenth aspect of the present invention, in the drive transmission device according to any one of the second to eighth aspects, at least one of the seat portion and the thrust receiving surface is formed of a resin having high slidability. It is characterized by being.

According to an eleventh aspect of the present invention, in the drive transmission device according to any one of the first to tenth aspects, the screw member is made of carbon steel.
According to a twelfth aspect of the present invention, in the drive transmission device according to any one of the first to tenth aspects, the screw member is formed of stainless steel.
According to a thirteenth aspect of the present invention, in the drive transmission device according to any one of the first to tenth aspects, the shaft is made of carbon steel.
According to a fourteenth aspect of the present invention, in the drive transmission device according to any one of the first to tenth aspects, the shaft is formed of stainless steel.
According to a fifteenth aspect of the present invention, in the drive transmission device according to any one of the first to tenth aspects, the screw member is surface-treated by making it chrome-free.
According to a sixteenth aspect of the present invention, in the drive transmission device according to any one of the first to tenth aspects, the shaft is subjected to a surface treatment by making it chrome-free.
The invention according to claim 17 has the drive transmission device according to any one of claims 1 to 16.

  According to the present invention, for example, in a drive transmission device that is arranged in the same straight line and is required to perform drive transmission between two separated axes, it is possible to eliminate the press-fitting and intervening components and reduce the cost of the “coupling component”. With a simple structure such as “+ screw + drive shaft”, drive transmission without loosening of the screw can be performed. Further, it is possible to perform drive transmission with little rotation unevenness.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, the outline of the configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG. Image forming units 6Y, 6M, 6C, and 6Bk corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the lower surface of the intermediate transfer belt 8 as an unfixed image carrier of the intermediate transfer unit 10. Has been. The four image forming units 6Y, 6M, 6C, and 6Bk installed in the apparatus main body 100 have substantially the same structure except that the color of the toner used in the image forming process is different.
The image forming unit 6 includes a photosensitive drum 1 as an image carrier, a charging unit (not shown) disposed around the photosensitive drum 1, a developing device 5 as a developing unit, a cleaning unit (not shown), and the like. It consists of An image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1, and a desired toner image is formed on the photosensitive drum 1.
The photosensitive drum 1, the charging unit, the developing device 5, and the cleaning unit constituting the image forming unit 6 are configured to be detachably installed on the image forming apparatus main body 100. These can be integrated into a process cartridge that is detachably installed in the apparatus main body 100.

The photosensitive drum 1 is rotationally driven in a clockwise direction by a drive transmission device to be described later, and the surface of the photosensitive drum 1 is uniformly charged by a charging roller (not shown) at the position of the charging unit (charging process).
Thereafter, the surface of the photosensitive drum 1 reaches an irradiation position of a laser beam emitted from an exposure unit (not shown), and an electrostatic latent image is formed by exposure scanning at this position.
Thereafter, the surface of the photosensitive drum 1 reaches a position facing the developing device 5, and the electrostatic latent image is developed at this position to form a desired toner image (developing process).
Thereafter, the surface of the photosensitive drum 1 reaches a position facing the intermediate transfer belt 8 and the primary transfer bias roller 9, and the toner image on the photosensitive drum 1 is transferred onto the intermediate transfer belt 8 at this position. (Primary transfer process).
At this time, a small amount of untransferred toner remains on the photosensitive drum 1.

Thereafter, the surface of the photoconductor 1 reaches a position facing the cleaning unit, and untransferred toner remaining on the photoconductor drum 1 at this position is collected by a cleaning blade (not shown). After cleaning, the potential of the surface of the photosensitive drum 1 is initialized by a neutralizing roller (not shown).
Thus, a series of image forming processes performed on the photosensitive drum 1 is completed.

  As shown in FIG. 1, the above-described image forming process is performed in each of the four image forming units 6Y, 6M, 6C, and 6Bk. That is, laser light based on image information from an exposure unit (optical writing device) (not shown) disposed below the image forming unit is applied to the photosensitive drums of the image forming units 6Y, 6M, 6C, and 6Bk. Irradiated toward. Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 8 in an overlapping manner. Thus, a color image is formed on the intermediate transfer belt 8.

The four primary transfer bias rollers 9Y, 9M, 9C, and 9Bk respectively sandwich the intermediate transfer belt 8 with the photosensitive drums 1Y, 1M, 1C, and 1Bk to form a primary transfer nip. The primary transfer bias rollers 9Y, 9M, 9C, and 9Bk are applied with a transfer bias having a polarity opposite to the polarity of the toner.
The intermediate transfer belt 8 travels counterclockwise and sequentially passes through the primary transfer nips of the primary transfer bias rollers 9Y, 9M, 9C, and 9Bk. In this way, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1Bk are primarily transferred while being superimposed on the intermediate transfer belt 8.

Thereafter, the intermediate transfer belt 8 onto which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 19 as a secondary transfer unit. The color toner image formed on the intermediate transfer belt 8 is transferred onto a transfer sheet P as a recording medium conveyed to the secondary transfer nip position.
Thus, a series of transfer processes performed on the intermediate transfer belt 8 is completed.
A plurality of transfer sheets P are stored in a paper feeding unit 26 disposed in the lower part of the apparatus main body 100, and are separated and fed one by one by a paper feeding roller 27. The fed transfer paper P is temporarily stopped by the registration roller pair 28, and after the oblique deviation is corrected, it is conveyed toward the secondary transfer nip by the registration roller pair 28 at a predetermined timing. Then, a desired color image is transferred onto the transfer paper P at the secondary transfer nip.

The transfer paper P onto which the color image has been transferred at the position of the secondary transfer nip is conveyed to the fixing unit 20, where the color image transferred to the surface is fixed by heat and pressure generated by the fixing roller and the pressure roller. The
After the fixing, the transfer paper P is discharged as an output image to the paper discharge unit 30 formed on the upper surface of the apparatus main body by the paper discharge roller pair 29 and stacked.

FIG. 2 shows a driving configuration of the photosensitive drum 1. In FIG. 2, reference numeral 50 denotes a black photosensitive drum driving motor, 51 denotes an intermediate transfer driving motor, 52 denotes a black photosensitive drum driving gear, 53 denotes a cyan photosensitive drum driving gear, and 54 denotes a magenta photosensitive drum driving. Reference numeral 55 denotes a yellow photosensitive drum driving gear.
This configuration is an example provided with a small module large diameter gear in order to achieve high precision driving. The shafts of the respective photosensitive drums and the drive shaft for transmitting the drive from the motor are separated from each other, and the configuration is such that priority is given to the detachability of the photosensitive unit.

3 and 4 show the drive transmission device 58 for the black photosensitive drum 1Bk. In FIG. 3, reference numeral 56 denotes a driving side ball bearing, and 57 denotes a driving side coupling. In FIG. 4, reference numeral 59 denotes a photosensitive member shaft as a driven shaft, 60 denotes a driving shaft, 61 denotes a photosensitive member side coupling as a driven side coupling, and 62 denotes a photosensitive member side ball bearing.
In the present embodiment, the photoconductor side coupling 61 enters the drive side coupling 57. Further, the centering between the two couplings is achieved by lightly press-fitting the drive side ball bearing 56 and the photoreceptor side ball bearing 62 into the same component.

FIG. 5 shows a coupling structure on the drive side. The drive side coupling 57 is attached to the drive shaft 60 by a drive side coupling fastening screw 63 as a screw member.
FIG. 6 shows a coupling configuration on the photoconductor side. The photoconductor side coupling 61 is attached to the photoconductor shaft 59 by a photoconductor side coupling fastening screw 64 as a screw member.
FIG. 7 shows a cross-sectional view of the drive side coupling configuration. However, the features of the present invention are not clearly shown in this figure. The drive shaft 60 is positioned on the black photosensitive drum drive gear 52 by a drive side ball bearing 56 and a collar 65, and the drive side coupling 57 is prevented from coming off from the drive shaft 60 by a drive side coupling fastening screw 63.
That is, the drive side coupling fastening screw 63 has a seat portion (flange) 60a having a diameter larger than the insertion hole 57a through which the drive shaft 60 of the drive side coupling 57 is inserted, and the seat portion 60a is on the drive side. It is prevented from coming off by contacting the thrust receiving surface 57 b of the coupling 57.

The gist of the present invention will be described with reference to FIG. In FIG. 8 and subsequent figures, cross-sectional display by hatching is omitted. At the position where the parallel pin 66 driven in the direction orthogonal to the drive shaft 60 hits the pin groove 57 c of the drive side coupling 57, the insertion side end surface of the drive shaft 60 is slightly smaller than the thrust receiving surface 57 b of the drive side coupling 57. The tolerance is set so as to protrude the head, and when the drive side coupling fastening screw 63 is tightened, a clearance g is formed between the thrust receiving surface 57b and the opposing surface (seat surface) of the seat portion 60a. It has become. In other words, the drive side coupling fastening screw 63 and the drive shaft 60 are slidable in the axial direction within the range of the clearance g. The parallel pin 66 and the pin groove 57c are omitted in FIG.
Even when the drive shaft 60 rotates in the direction to loosen the drive side coupling fastening screw 63, the contact between the seat surface of the seat portion 60a and the thrust receiving surface 57b is absent or reduced, so the drive side coupling fastening screw It is possible to prevent a problem that 63 is loosened and the drive side coupling 57 is detached from the drive shaft 60.
Therefore, the number of parts can be reduced with a simple and simple structure, and the exchangeability when the coupling is broken is also good.
Further, since it is not necessary to interpose a low-friction component such as a washer between the seat portion 60a and the thrust receiving surface 57b or press-fit a coupling, it is possible to reduce the man-hours and the parts cost.

A second embodiment will be described with reference to FIG. In addition, the same part as the said embodiment is shown with the same code | symbol, The description on the structure and function which were already demonstrated is abbreviate | omitted as long as there is no special need, and only the principal part is demonstrated (same in other following embodiment).
This embodiment is characterized in that the clearance g is secured by using a stepped drive side coupling fastening screw 67. Here, the insertion side end surface of the drive shaft 60 does not need to protrude from the thrust receiving surface 57b, and the clearance g is obtained by bringing the stepped portion 67b of the drive side coupling fastening screw 67 into contact with the end surface of the drive shaft 60. Can do.
Therefore, it is possible to obtain a loosening prevention function by changing only the screw member while using the common parts. The clearance 67 may be obtained by slightly burying the stepped portion 67 b in the end surface of the drive shaft 60.

In each of the above embodiments, since the play (clearance g) is provided in the thrust direction, a clearance between the outer diameter of the drive shaft and the inner diameter of the drive-side coupling component is also required. In couplings that require this, there is a risk of increasing rotational unevenness.
The embodiment described below addresses this problem, and reduces the contact area between the seat of the screw member and the thrust receiving surface of the coupling member, and suppresses the force received in the loosening direction of the screw member, thereby preventing the loosening function. It is characterized by obtaining.
In the third embodiment shown in FIG. 10, a small-diameter hole 68 is spaced in the circumferential direction in a region corresponding to the seat portion 60a of the driving side coupling fastening screw 63 on the thrust receiving surface 57b of the driving side coupling 57. A plurality of them are formed.
As a result, the contact area between the seat surface of the seat portion 60a and the thrust receiving surface 57b is reduced, and the force received by the seat surface when the drive shaft 60 starts, stops, and reverses can be reduced. As a whole, the seat surface and the thrust receiving surface 57b are in contact with each other, so that no backlash occurs in the thrust direction.

FIG. 11 shows a fourth embodiment. In the third embodiment, in order to improve the coaxiality (runout) after assembly, a dimensional tolerance in the thrust direction must be included in the entire range received by the seat portion 60a of the drive side coupling fastening screw 63. Poor nature and cost increases.
In order to cope with this problem, in this embodiment, a ring-shaped convex portion (circumferential rib) 69 is formed in a region corresponding to the seat portion 60a of the thrust receiving surface 57b. Therefore, the dimensional restriction in the thrust direction is limited to the upper surface of the ring-shaped convex portion 69.
The convex portion 69 is formed in a state where the thrust receiving surface 57b is dug down, and the upper surface of the convex portion 69 (the contact surface with the seat 60a) and the thrust receiving surface 57b before dug down coincide.

FIG. 12 shows a fifth embodiment. In the fourth embodiment, particularly in the case of a coupling component having a small diameter, the seat portion 60a of the driving side coupling fastening screw 63 and the thrust receiving surface 57b of the driving side coupling 57 become very small. If the portion 69 is provided, the mold for injection molding becomes thin and the mold may be damaged.
In this embodiment, in order to cope with this problem, a plurality of convex portions (ribs) 70 are formed radially on the thrust receiving surface 57b. Similarly to the fourth embodiment, the convex portion 70 is formed in a state where the thrust receiving surface 57b is dug down, and the upper surface (the contact surface with the seat portion 60a) of the convex portion 70 and the original thrust receiving surface 57b are Match.
With such radial ribs, for example, with about 3 to 6 ribs, even small-diameter coupling parts can be injection molded.

FIG. 13 shows a sixth embodiment. In the present embodiment, thin cylindrical convex portions (ribs) 71 as columnar protrusions are formed on the thrust receiving surface 57b. Similar to the fourth embodiment, the convex portion 71 is formed in a state where the thrust receiving surface 57b is dug down, and the upper surface (the contact surface with the seat portion 60a) of the convex portion 71 and the original thrust receiving surface 57b are Match.
Similar to the fifth embodiment, a small-diameter coupling component can be used.

FIG. 15 shows a seventh embodiment. For example, the upper surface of the radial convex portion 70 shown in FIG. 12 is a flat surface, and as shown in FIG. 14, the seat surface of the seat portion 60a and the upper surface of the convex portion 70 are in contact with each other.
In the present embodiment, in order to further reduce the contact area, a chamfered portion (R portion) 70a is provided on the upper surface (top surface) of the convex portion 70, and the axial cross section on the side in contact with the seat portion 60a is curved. Forming.
In this way, the contact area with the seat 60a can be further reduced, so that the force in the screw loosening direction can be reduced, and the loosening prevention function of the drive side coupling fastening screw 63 can be further enhanced.
In addition, the wear of the mold can be reduced, and as a result, the manufacturing cost can be reduced. It can implement similarly also in another convex part (rib).

FIG. 16 shows an eighth embodiment. For example, in a driving condition in which an excessive torque (or a large acceleration) is applied when receiving a force in the loosening direction rather than when the seat 60a receives a force in the tightening direction, the rib shape is symmetrical with respect to the rotation direction. There is still a risk of screw loosening.
In the present embodiment, in order to cope with this problem, a plurality of convex portions (ribs) 72 that are asymmetric with respect to the rotational direction are formed radially on the thrust receiving surface 57b. Thereby, the force in the loosening direction of the drive side coupling fastening screw 63 can be reduced, and the force in the screw fastening direction can be increased.
Therefore, when the seat portion 60a receives a force in the loosening direction, a screw loosening prevention function can be obtained even under a driving condition in which excessive torque is applied.

FIG. 17 shows a ninth embodiment. In the present embodiment, similar to the eighth embodiment, it is an object to eliminate the above-described concern about the rib shape symmetric with respect to the rotation direction.
When the radial ribs 70 are provided, the taper amount of each rib 70 is individually defined, and the draft on the side where the ribs are desired to be bent (screw seating surface tightening direction; arrow R side) is minimized (including straightening). The taper surface 70b is formed by increasing the draft angle on the opposite side (screw seat surface loosening direction; arrow L side).
That is, the tapered surface 70b is formed in order to bend easily in the direction in which the drive side coupling fastening screw 63 is tightened and to be difficult to bend in the loose direction.
When receiving force in the direction of loosening of the screw seat surface, the rib 70 does not flex as much as possible (less deviation), and when receiving force in the direction of tightening of the screw seat surface, the rib 70 bends greatly to further prevent screw loosening. Can be increased.

When the rib is provided as described above to reduce the contact area between the seat portion 60a of the drive side coupling fastening screw 63 and the thrust receiving surface 57b of the drive side coupling 57, the friction coefficient of the rib portion is further reduced. Therefore, the rib surface may be coated (tenth embodiment). A coating material with a low coefficient of friction is desirable.
Further, in order to further reduce the coefficient of friction between the seat portion 60a and the ribs, either one or both of the seat portion 60a and the ribs may be formed of a resin having high slidability (for example, polyacetal) (11th embodiment). ). In this case, you may form only a contact part with the said resin.

The material of either or both of the drive side coupling fastening screw 63 and the drive shaft 60 may be formed of carbon steel (for example, SWCH 18) with low processing cost (rich in header processability) (11th embodiment). . Cost reduction can be realized.
Either or both of the drive-side coupling fastening screw 63 and the drive shaft 60 may be made of stainless steel (for example, SUS304) at a low processing cost (rich in header processability) (a twelfth embodiment). . Cost reduction can be realized.
The surface treatment of one or both of the drive side coupling fastening screw 63 and the drive shaft 60 may be made chrome-free without environmental influences (a thirteenth embodiment). A screw loosening prevention function can be obtained while responding to the environment.

  In each of the above-described embodiments, the driving side coupling has been described. However, the driving side coupling, which is the driven side, can be similarly performed. Further, the driving of the black photosensitive drum has been described, but the same applies to the driving of the other photosensitive drums.

1 is a schematic front view of an image forming apparatus according to a first embodiment of the present invention. It is a perspective view which shows the drive structure of a photoconductor drum. It is a perspective view which shows the drive transmission device of a black photosensitive drum. It is a perspective view which shows the connection part of the drive transmission device of a black photosensitive drum. It is a perspective view which shows the attachment state of a drive side coupling. It is a perspective view which shows the attachment state of a photoreceptor side coupling. It is a section perspective view of a drive side coupling. It is a cross-sectional perspective view which shows the fastening state of the screw member of a drive side coupling. It is a cross-sectional perspective view which shows the fastening state of the screw member of the drive side coupling in 2nd Embodiment. It is a top view which shows the thrust receiving surface of the drive side coupling in 3rd Embodiment. It is a top view which shows the thrust receiving surface of the drive side coupling in 4th Embodiment. It is a top view which shows the thrust receiving surface of the drive side coupling in 5th Embodiment. It is a top view which shows the thrust receiving surface of the drive side coupling in 6th Embodiment. It is sectional drawing which shows the contact state of the rib of the thrust receiving surface of the drive side coupling in 5th Embodiment, and the seat surface of a screw member. It is sectional drawing which shows the contact state of the rib of the thrust receiving surface of the drive side coupling in 7th Embodiment, and the seat surface of a screw member. It is a top view which shows the thrust receiving surface of the drive side coupling in 8th Embodiment. It is sectional drawing which shows the contact state of the rib of the thrust receiving surface of the drive side coupling in 9th Embodiment, and the seat surface of a screw member.

Explanation of symbols

57 Driving side coupling as coupling 57a Insertion hole 57b Thrust receiving surface 60 Driving shaft as shaft 61 Photoconductor side coupling as coupling 63 Driving side coupling fastening screw as screw member 63a Seat portion 64 Screw member Photoconductor side coupling fastening screw 69 Ring-shaped convex portion 70 Radial convex portion 70b Tapered surface as taper 71 Columnar convex portion 72 Asymmetric radial convex portion g Clearance

Claims (17)

The shaft is inserted into at least one of the couplings, and a screw member having a seat portion larger than the diameter of the insertion hole is screwed into the insertion end portion of the shaft, and the coupling is attached so as not to be detached. In the drive transmission device,
A clearance is provided between the seat portion of the screw member and the thrust receiving surface of the coupling facing the screw member, and the shaft and the coupling are assembled to be slidable in the axial direction within the clearance. A drive transmission device characterized by that. The shaft is inserted into at least one of the couplings, and a screw member having a seat portion larger than the diameter of the insertion hole is screwed into the insertion end portion of the shaft, and the coupling is attached so as not to be detached. In the drive transmission device,
A drive transmission device, wherein a contact area between the seat portion of the screw member and a thrust receiving surface of the coupling facing the seat portion is reduced. The drive transmission device according to claim 2, wherein
A drive transmission device, wherein a ring-shaped convex portion is formed on the thrust receiving surface. The drive transmission device according to claim 2, wherein
A drive transmission device, wherein a radial convex portion is formed on the thrust receiving surface. The drive transmission device according to claim 2, wherein
A drive transmission device, wherein a cylindrical convex portion is formed on the thrust receiving surface. The drive transmission device according to claim 2, wherein
A drive transmission device, wherein radial thrusts asymmetric with respect to the rotational direction of the shaft are formed on the thrust receiving surface. The drive transmission device according to claim 4 or 6,
A drive transmission device characterized in that a taper is formed on the convex portion so that the screw member is easily bent in a tightening direction and is not easily bent in a loosening direction of the screw member. The drive transmission device according to any one of claims 2 to 7,
The drive transmission device, wherein an axial cross section of the convex portion on a side contacting the seat portion is curved. The drive transmission device according to any one of claims 2 to 8,
A drive transmission device, wherein a coating is applied to at least a portion of the thrust receiving surface that contacts the seat portion. The drive transmission device according to any one of claims 2 to 8,
At least one of the seat portion and the thrust receiving surface is formed of a resin having high slidability. The drive transmission device according to any one of claims 1 to 10,
The drive transmission device, wherein the screw member is made of carbon steel. The drive transmission device according to any one of claims 1 to 10,
The drive transmission device, wherein the screw member is made of stainless steel. The drive transmission device according to any one of claims 1 to 10,
The drive transmission device, wherein the shaft is made of carbon steel. The drive transmission device according to any one of claims 1 to 10,
A drive transmission device characterized in that the shaft is made of stainless steel. The drive transmission device according to any one of claims 1 to 10,
A drive transmission device characterized in that the screw member is surface-treated by making it chrome-free. The drive transmission device according to any one of claims 1 to 10,
A drive transmission device characterized in that the shaft is surface-treated by making it chrome-free. An image forming apparatus comprising the drive transmission device according to claim 1.

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