JPH07319329A - Drum assembly for image forming device - Google Patents

Abstract

PURPOSE:To restrain the vibration of a photoreceptor drum and to form a high-quality toner image on the drum by providing the mating engaging part for rotating the drum around the shaft line of the drum. CONSTITUTION:The engaging part consisting of two notches 10 and 11 is provided on the photoreceptor drum 1 and the mating engaging part consisting of two projected parts 12 and 13 is provided on a drum shaft 2. The number of the engaging parts is properly set but must be plural. In short, at least two engaging parts arranged by leaving a space between them in the peripheral direction of the drum 1 are provided for one end member and the mating engaging parts engaged therewith are provided on the drum shaft 2, so that the rotation of the drum shaft 2 around the shaft line is transmitted to the drum 1 and the drum 1 is driven to be rotated around the shaft line. By providing plural engaging parts on the end member and the mating engaging parts corresponding thereto on the drum shaft 2, the vibration of the drum 1 is restrained and the high-quality toner image is formed on the surface of a drum main body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive member having a hollow cylindrical drum main body having a photosensitive layer formed on the outer surface thereof, and end members fitted and fixed to openings at respective axial end portions of the main body. The present invention relates to a drum assembly of an image forming apparatus having a body drum and a drum shaft that is inserted into a center hole formed in the center of each end member and extends through the inside of the drum body.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile, a drum assembly of the above type is used, and a drum shaft thereof is rotationally driven to rotate a photosensitive drum about its axis. It is well known in the art to form an electrostatic latent image on the photosensitive layer of the drum body and visualize it as a toner image.

In a conventional drum assembly, one engaging member consisting of a notch is formed in one end member of the photosensitive drum, and a drum-shaped projection consisting of a pin-like projection 1 is formed.
Two mating engaging parts are attached, and with the photosensitive drum and the drum shaft assembled, the engaging part of the photosensitive drum and the mating engaging part of the drum shaft are engaged with each other, thereby rotating the drum shaft. It was configured to transfer to a photoconductor drum and rotate the drum about its axis. At that time, the engaging portion of the photoconductor drum and the mating engaging portion of the drum shaft are fitted together by a shrink fit to prevent the photoconductor drum from rattling in the direction of rotation about the drum shaft during rotation. It was

On the other hand, in this type of drum assembly,
The drum is detachably attached to the drum shaft in the axial direction so that the photosensitive drum can be replaced.
At that time, in order to facilitate the attachment / detachment, the center hole formed in each end member of the photoconductor drum and the drum shaft are fitted together by a clearance fit, and a slight gap is formed between the peripheral edge of the center hole and the drum shaft. There is a gap. This makes it possible to easily pull out the photosensitive drum from the drum shaft or easily insert the drum into the drum shaft.

However, according to the drum assembly having the above structure, when the photosensitive drum rotates, the photosensitive drum may slightly vibrate around the engaging portion between the engaging portion and the mating engaging portion. It turned out to be. In the past, when it was possible to prevent rattling of the photosensitive drum in the direction of rotation around the drum axis, it was thought that it would be possible to rotate the photosensitive drum without rattling it. In accordance with this idea, one engaging portion consisting of a notch is formed in the end member of the photosensitive drum, and one counterpart engaging portion consisting of a protrusion engaging with this engaging portion is also provided on the drum shaft. However, as a result of the study by the present inventor, when the photosensitive drum is rotated, the engaging portions of the engaging portion and the mating engaging portion are engaged with each other. It became clear that the photosensitive drum would vibrate around. When the photosensitive drum vibrates in this way, the image quality of the toner image formed on the surface of the drum body deteriorates significantly.

If the center hole of the photoconductor drum and the drum shaft are fitted together by a shrink fit, the vibration of the photoconductor drum described above can be prevented. By doing so, the photoconductor drum can be attached to and detached from the drum shaft. However, it is inappropriate to adopt such a configuration.

[0007]

SUMMARY OF THE INVENTION The present invention has been made based on the above-mentioned novel recognition. An object of the present invention is to suppress the vibration of the above-mentioned photosensitive drum and to provide a high quality on the drum. An object is to provide a drum assembly capable of forming a toner image.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a drum assembly of the type described at the beginning in which at least one of the two end members is spaced from each other in the circumferential direction of the photosensitive drum. At least two engaging portions disposed apart from each other are provided, the drum shaft is engaged with each of the plurality of engaging portions, and the rotation about the axis of the drum shaft is transmitted to the photosensitive drum. A configuration is proposed in which a mating engagement portion is provided for rotating the body drum around its axis.

At this time, it is particularly advantageous that the plurality of engaging portions provided on the end member are arranged around the axis of the photosensitive drum at substantially equal angles with each other.

Further, it is preferable that the engaging portion and the mating engaging portion are detachably engaged with each other so that the photosensitive drum and the drum shaft can be inserted and removed in the axial direction thereof.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, and the above-mentioned conventional drawbacks will be more specifically clarified with reference to the drawings.

FIGS. 1 to 3 show a drum assembly according to an embodiment of the present invention. The drum assembly shown here has a photosensitive drum 1 and a drum shaft 2. FIG. 1 shows a state in which the photosensitive drum 1 is pulled out from the drum shaft 2, FIG. 2 is a longitudinal sectional view when the both are assembled, and FIG. 3 is a view of the drum assembly seen from the right side of FIG. FIG. 3 is a side view schematically showing the situation.

The photoconductor drum 1 has a hollow cylindrical drum main body 3 having a photosensitive layer formed on the outer surface thereof, and end members fitted and fixed to openings 4 and 5 at respective axial end portions of the main body 3. It has 6 and 7. In this example, each of the end members 6 and 7 is formed in a disc shape, and these are fixed to each end of the drum body 3 by press fitting or an adhesive. The drum shaft 2, which constitutes the other element of the drum assembly, is rotatably supported by the image forming apparatus main body (not shown).

Center holes 8 and 9 are formed in the central portions of the respective end members 6 and 7 of the photosensitive drum 1, and the drum shaft 2 is inserted into these center holes 8 and 9 as shown in FIG. The shaft 2 extends through the inside of the drum body 3. Further, as clearly shown in FIG. 3, the one end member 6 has a notch 10, which communicates with the center hole 8 thereof and extends in the radial direction thereof.
An engaging portion 11 is formed. A plurality of engaging portions composed of such notches are provided in one end member 6, and two in the example shown in the figure.
One is provided. The notches 10 and 11 are arranged at intervals in the circumferential direction of the photosensitive drum 1.

On the other hand, the drum shaft 2 is integrally fixed with two mating engaging portions consisting of pin-shaped protrusions 12 and 13 protruding in the radial direction thereof, and as shown in FIGS. With the drum 1 assembled to the drum shaft 2, each protrusion 12,
13 engages with each of the plurality of notches 10, 11. In the example shown in FIG. 3, projection pairs 14 and 15 facing each other are provided in the notches 10 and 11, respectively.
The protrusions 12 and 13 are fitted between 4 and 15 by means of a shrink fit.

Here, as shown in FIG. 1, a gear 16 is fixed to one end side of the drum shaft 2 which is the inner side of the image forming apparatus main body, and the gear 16 is the drive gear 1 on the image forming apparatus main body side.
Driven by meshing with 7, the drum shaft 2 rotates about its central axis. At this time, since the protrusions 12 and 13 and the notches 10 and 11 are engaged with each other, the rotational driving forces F and F are transmitted from the drum shaft 2 to the photosensitive drum 1, and the photosensitive drum 1 is It is rotationally driven around the central axis O in the direction of arrow a (FIG. 2). In this way, the pair of protrusions 12 and 13 forming an example of the mating engaging portion transmits the rotation around the axis of the drum shaft 2 to the photosensitive drum 1,
It serves to rotate the photosensitive drum 1 around its axis.

As described above, while the photosensitive drum 1 rotates, an electrostatic latent image is formed on the surface of the drum main body 3, and the electrostatic latent image is visualized as a toner image.
The image is transferred to a transfer material (not shown) by a transfer device (not shown). Drum body 3 after toner image transfer
The toner remaining on the surface of the is cleaned and removed by a cleaning device (not shown).

While using the photosensitive drum 1 as described above, when the drum 1 is scratched or has reached the end of its life, it is necessary to replace the photosensitive drum 1 with a new one. In such a case, the photosensitive drum 1 is
As shown by an arrow X in FIG. 2, the drum 1 is pulled in the axial direction, toward the front side of the image forming apparatus main body, and is pulled out from the drum shaft 2. Then, a new photosensitive drum is mounted on the drum shaft 2 in the reverse order.

In this way, the photosensitive drum 1 and the drum shaft 2 are
Is removable, but in order to facilitate mutual attachment / detachment at this time, the center holes 8 and 9 of the photosensitive drum 1 and the drum shaft 2 are fitted with each other by a clearance fit. There is. That is, as exaggeratedly shown in FIG. 3, a slight gap G is generated between the peripheral edge of the center hole 8 and the outer peripheral surface of the drum shaft 2, and similarly between the other center hole 9 and the drum shaft 2. The photosensitive drum 1 and the drum shaft 2 are assembled so that a gap is formed, and a slight amount of looseness is provided between them.

When the photosensitive drum 1 is assembled to the drum shaft 2, the protrusions 12 and 13 are press-fitted between the protrusion pairs 14 and 15 of the notches 10 and 11, respectively, and the photosensitive drum 1 is removed from the drum shaft 2. When removing, the protrusions 12 and 13 are forcibly pulled out from between the protrusion pairs 14 and 15.

The basic construction of the drum assembly in this embodiment is as described above. Before clarifying the more detailed construction and operation, an example of the conventional drum assembly described above will be described with reference to FIGS. This will be described with reference to FIG.

In the drum assembly shown in FIGS. 7 to 9, one end of the photosensitive drum 1 is formed with a notch 10, and the drum shaft 2 is provided with the notch 10. There is provided one mating engaging portion consisting of the protrusion 12 that engages with. That is, it differs from the drum assembly shown in FIGS. 1 to 3 in that the number of engaging portions and the number of mating engaging portions are one, and other configurations are the same as those in FIGS. 1 to 3. It is also the same that the drum shaft 2 and the center hole 8 of the photosensitive drum 1 are fitted by a clearance fit.

Here, the photosensitive drum 1 shown in FIGS. 7 to 9 is also driven to rotate in the direction shown by the arrow a in FIG. 9 by the rotation of the drum shaft 2. At this time, one protrusion 12 and this are provided. The rotational driving force F is transmitted from the drum shaft 2 to the photosensitive drum 1 through the one notch 10 that is fitted. At this time, when the magnitude of the driving force F slightly fluctuates, the photosensitive drum 1 is broken by the broken line around the engagement portion between the notch 10 and the protrusion 12, that is, the position shown by C in FIG. There is a risk that the photosensitive drum 1 may vibrate due to the displacement in the direction of the arrow H as indicated by. In addition, an external vibration force applied to the photosensitive drum 1 by an image forming process element (not shown) contacting the photosensitive drum 1 may cause the photosensitive drum 1 to vibrate around the point C.

As described above, conventionally, when the photosensitive drum 1 is rotated, if it is prevented from rattling in the rotational direction around the drum shaft 2, the photosensitive drum 1 is not vibrated. Since it was thought that it could be rotated by means of, it was necessary to form one notch 10 on the side of the photoconductor drum 1 and fit one protrusion 12 on the side of the drum shaft 2 to this by means of shirring. . However, as a result of the study by the present inventor, when the center hole 8 of the photosensitive drum 1 and the drum shaft 2 are fitted by a clearance fit, as described above, when the drum shaft 1 rotates, it vibrates about the point C. It turns out that it will happen.

Therefore, in the embodiment of the present invention shown in FIGS. 1 to 3, as described above, the two notches 10, which are arranged in the end member 6 at intervals in the circumferential direction of the photosensitive drum 1,
11 is provided, and the two notches 10 and 11 are engaged with the two protrusions 12 and 13 protruding from the drum shaft 2, respectively, whereby rotational driving forces F and F are applied from the drum shaft 2 to the photosensitive drum 1. Is configured to communicate. By providing a plurality of pairs of cutouts and protrusions in this manner, the central hole 8 of the photosensitive drum 1,
Even if there is some gap G between the drum shaft 9 and the drum shaft 2, it can be rotated without causing the vibration as shown in FIG.

In the example shown in FIGS. 1 to 3, the photoconductor drum 1 is provided with an engaging portion composed of two notches 10 and 11, and the drum shaft 2 is also composed of two protrusions 12 and 13. Although the engaging portions are provided, the number can be set as appropriate as long as a plurality of engaging portions are provided. The point is that for one end member, the photosensitive drum 1
At least two circumferentially spaced from each other
One engaging portion is provided, and a mating engaging portion that engages with each of the engaging portions is provided toward the drum shaft 2, and the rotation around the axis of the drum shaft 2 is transmitted to the photoconductor drum 1.
It can be driven to rotate around.

At this time, it is desirable that the plurality of engaging portions provided for one end member are arranged around the axis O of the photosensitive drum at substantially equal angles. Figure 3
In the example shown in FIG. 2, the two notches 10 and 11 are arranged around the axis O of the photosensitive drum at an angle α of 180 ° with each other, and the protrusions 12 and 13 are engaged with the notches 10 and 11, respectively. When making three notches, the angle between them should be 1
The angle is 20 °, and when four are also provided, the angle formed by them is set to 90 °.

With this structure, the rotational driving force F applied to the photosensitive drum 1 from the protrusions 12 and 13 of the drum shaft 2 acts point-symmetrically with respect to the axis O of the photosensitive drum 1, and A uniform driving force is applied to the drum 1 in its circumferential direction. Therefore, when the photosensitive drum 1 rotates,
As shown in FIG. 9, it is possible to more reliably prevent the problem of vibration about the point C, and to avoid the problem that the toner image formed on the drum body 3 is blurred. This structure can be applied to any of the embodiments described later.

In the embodiment shown in FIGS. 1 to 3, the notches 10 and 11 and the protrusions 12 and 13 are press-fitted, that is, they are fitted to each other by shirring, but a plurality of pairs of notches and protrusions are used. Since it is provided, even if the notch and the protrusion are fitted by a clearance fit or an intermediate fit, it is possible to prevent the problem that the photoconductor drum 1 vibrates when it rotates. Alternatively, as shown in FIG. 4, each notch 10, 11
Even if the protrusions 12 and 13 have a large play and are fitted to each other, the vibration of the photosensitive drum can be prevented. As described above, any method may be used for the fitting eyes of the engaging portion and the mating engaging portion. In either case, the engagement portion and the mating engagement portion may be detachably engaged with each other so that the photosensitive drum 1 and the drum shaft 2 can be inserted and removed in the axial direction.

Further, instead of making the engaging portion provided on the photosensitive drum 1 a notch, the engaging portion may be made a protrusion and, conversely, the mating engaging portion provided on the drum shaft 2 may be made a notch. The form of the mating portion and the mating engaging portion can be appropriately selected.

In the example shown in FIG. 5, the end member 6 of the photosensitive drum 1 is provided with a plurality of engaging portions formed by pins 18 which are arranged at intervals in the circumferential direction of the drum so as to project from the drum shaft. Two
3 shows an example in which a circular plate 19 is fixed and hole-shaped notches 20 that engage with the pins 18 are formed in the circular plate 19.

Further, in the embodiment shown in FIG. 6, one end member 6 of the photosensitive drum 1 is integrally provided with a boss portion 21 which is concentric with the center hole 8 thereof, and the boss portion 21 is provided with the photosensitive member. A plurality of engaging portions are formed of recesses 22 which are spaced from each other in the circumferential direction of the drum 1 and are arranged at substantially equal angles around the axis thereof. A cylindrical body 23 is integrally attached to the drum shaft 2 concentrically with the axis of the drum shaft 2, and the cylindrical body 23 has a protrusion 2 that is detachably engaged with each of the recesses 22 described above.
A mating engagement portion consisting of 4 is formed. Also in this embodiment, the photosensitive drum 1 and the drum shaft 2 are assembled, and the recesses 22 and the protrusions 24 thereof are engaged with each other, so that the drum shaft 2
Is transmitted to the photosensitive drum 1. Also in this case, the recess 22
A plurality of engaging portions formed of the protrusions 2
Since the mating engaging portion 4 is engaged, the vibration of the photosensitive drum 1 as shown in FIG. 9 can be prevented.

In each of the embodiments described above, the one end member 6 of the photosensitive drum 1 is provided with a plurality of engaging portions, but the other end member 7 is the same as in the above-described embodiments. It is also possible to provide a plurality of engaging portions and to engage the mating engaging portions provided on the drum shaft with each of them. Alternatively, a plurality of engaging portions may be provided on both of the end members 6 and 7, and a mating engaging portion on the drum shaft side may be engaged with each of the engaging portions. In short, at least one of the two end members of the photosensitive drum,
At least two engaging portions that are arranged at intervals in the circumferential direction of the photosensitive drum are provided, and the mating engaging portions on the drum shaft side are engaged with the engaging portions, respectively, and the rotation around the axis of the drum shaft is exposed. All you have to do is transfer it to the body drum and rotate this drum around its axis.

[0034]

According to the drum assembly of the first aspect of the present invention, the end member is provided with a plurality of engaging portions, and the corresponding engaging portions are provided on the drum shaft. It is possible to suppress vibration of the photosensitive drum due to an unthinkable cause and form a high-quality toner image on the surface of the drum main body.

According to the drum assembly of the second aspect,
The effects described above can be obtained more reliably.

According to the drum assembly of the third aspect,
It is possible to secure the detachability of the photosensitive drum and the drum shaft.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a photosensitive drum of a drum assembly according to an exemplary embodiment of the present invention is removed from a drum shaft.

FIG. 2 is a vertical cross-sectional view when the photosensitive drum shown in FIG. 1 is assembled to a drum shaft.

FIG. 3 is a side view as seen from the right side of FIG. 2, and is an explanatory diagram exaggeratingly showing a gap between the center hole of the photosensitive drum and the drum shaft.

FIG. 4 is a side view of a drum assembly showing another example.

FIG. 5 shows a drum assembly of yet another embodiment, FIG.
It is a perspective view similar to FIG.

FIG. 6 is a perspective view showing a drum assembly of still another embodiment.

FIG. 7 is a perspective view similar to FIG. 1, showing an example of a conventional drum assembly.

8 is a vertical sectional view of the drum assembly shown in FIG. 7 in which the drum shaft and the photosensitive drum are assembled.

9 is a side view similar to FIG. 3, in which the drum assembly shown in FIG. 8 is viewed from the right side of FIG.

[Explanation of symbols]

 1 Photosensitive Drum 2 Drum Shaft 3 Drum Body 4 Opening 5 Opening 6 End Member 7 End Member 8 Center Hole 9 Center Hole O Axis α Angle

Claims (3)

[Claims] 1. A photosensitive drum having a hollow cylindrical drum main body having a photosensitive layer formed on an outer surface thereof, and an end member fitted and fixed to an opening at each end of the main body in the axial direction, and In a drum assembly of an image forming apparatus having a drum shaft that is inserted into a center hole formed in the center of the end member and that extends through the inside of the drum body, at least one of the two end members, At least two engaging portions that are arranged at intervals in the circumferential direction of the photosensitive drum are provided, and the drum shaft is engaged with each of the plurality of engaging portions, so that the drum shaft is rotated around the axis of the drum shaft. A drum assembly for an image forming apparatus, comprising a mating engagement portion for transmitting rotation to a photosensitive drum and rotating the photosensitive drum around its axis. 2. The image forming apparatus according to claim 1, wherein the plurality of engaging portions provided on the end member are arranged at substantially equal angles to each other around the axis of the photosensitive drum. Drum assembly. 3. The photosensitive member and the drum shaft according to claim 1, wherein the engaging portion and the mating engaging portion are detachably engaged with each other so that the photosensitive drum and the drum shaft can be inserted and removed in the axial direction. A drum assembly of the described image forming apparatus.