JP7638172B2 - Photoconductor drum, method of manufacturing photoconductor drum, process unit and image forming apparatus - Google Patents

Description

The present invention relates to a photoconductor drum, a method for manufacturing a photoconductor drum, and a process unit and an image forming apparatus having a photoconductor drum.

An electrophotographic image forming apparatus has a photosensitive drum in an image forming section. FIG. 9 shows a schematic configuration of a conventional photosensitive drum 500, and is an exploded view of one end side. As shown in FIG. 9, the photosensitive drum 500 has a drum base tube 510, a drum flange 520, and a shaft 530. That is, the drum flanges 520 are press-fitted into both ends of the drum base tube 510, and the shaft 530 is inserted into the shaft hole 523 of the drum flange 520. The drum flange 520 has a flange portion 521 and a press-fit portion 522 formed coaxially, and the press-fit portion 522 is press-fitted into the inner periphery of the drum base tube 510. In addition, in a process unit having the photosensitive drum 500, a coupling gear 531 for receiving rotational drive from the main body of the image forming apparatus is fixed to one end of the shaft 530.

In such photosensitive drums, the drum flange is fixed to the shaft with a pin or a D-cut to prevent rotation (see, for example, Patent Document 1). In the illustrated photosensitive drum 500, the drum flange 520 is fixed to the shaft 530 with a pin 540 to prevent rotation. Here, FIG. 10 is a side view showing the outer end face (flange portion 521 side) of the drum flange 520, and FIG. 11 is a side view of the photosensitive drum 500 (coupling gear 531 is not shown).

The pin 540 is inserted into the shaft 530 so that their axes are perpendicular to each other (see FIG. 9). In addition, a groove 524 for inserting the pin 540 is formed on the outer end surface of the drum flange 520 (see FIGS. 9 and 10). That is, in the assembled photosensitive drum 500, the pin 540 is inserted into the groove 524, and the rotation of the shaft 530 is transmitted to the drum flange 520 via the pin 540 (the drum flange 520 is fixed to the shaft 530 without rotation). At this time, if the pin 540 has play in the groove 524, rattling will occur in the rotation of the photosensitive drum 500, so the pin 540 is pressed into the groove 524 and fixed so that there is no play.

JP 2005-24704 A

As in the above-mentioned conventional example, when the drum flange 520 is fixed to the shaft 530 by the pin 540 and the pin 540 fixed to the shaft 530 is pressed into the groove 524 of the drum flange 520, a slight misalignment occurs between the central axis of the drum 500 and the central axis of the shaft 530 due to the balance accuracy of the force direction when the metal pin 540 is pressed into the resin groove 524 and the coaxiality accuracy of the pin 540 and the groove 524, which affects the deflection (radial deflection) of the photosensitive drum 500, and there is a problem that the deflection of the photosensitive drum 500 is likely to increase. That is, the coaxiality of the pin 540 with respect to the outer diameter of the shaft 530 is difficult to achieve, and as shown in FIG. 12, the position of the pin 540 may be misaligned with respect to the outer diameter of the shaft 530. Similarly, the coaxiality of the groove 524 with respect to the outer diameter of the drum flange 520 is also difficult to achieve, and as shown in FIG. 13, the position of the groove 524 may be misaligned with respect to the outer diameter of the drum flange 520.

In this way, if the position of the pin 540 on the shaft 530 or the position of the groove 524 on the drum flange 520 is misaligned, it affects the wobble of the photosensitive drum 500. Wobble of the photosensitive drum 500 can cause registration misalignment and uneven print density. The same problem also occurs when the drum flange is fixed to the shaft with a D-cut to prevent rotation.

The present invention has been made in consideration of the above problems, and aims to provide a photosensitive drum, a manufacturing method for a photosensitive drum, a process unit, and an image forming apparatus that can reduce deflection of the drum surface relative to the shaft rotation axis.

In order to solve the above problems, the photosensitive drum of the first aspect of the present invention is a rotatably supported photosensitive drum used in an image forming apparatus, which comprises a cylindrical drum tube having an electrophotographic photosensitive member on its surface, flanges press-fitted and fixed to both axial ends of the drum tube, a drive transmission unit provided further outside the flange in the axial direction of the drum tube, and a cylindrical drive shaft that is the center of rotation of the flange and the drive transmission unit and passes through the center of rotation of the drum tube, the drive shaft being fixed to the drive transmission unit by a predetermined fixing method, and the drive transmission unit being fixed to the flange.

According to the above configuration, the rotation of the drive shaft is transmitted to the drum flange via the drive transmission unit, and the driving force is transmitted from the drive transmission unit to the drum flange by fixing the drive transmission unit to the drum flange. Therefore, even if deflection occurs in the drive transmission unit due to the rotation prevention fixing of the drive transmission unit to the drive shaft, the deflection can be prevented from being transmitted to the drum flange, and deflection of the drum surface (surface of the drum base tube) relative to the shaft rotation axis (rotation axis of the drive shaft) on the photosensitive drum can be reduced.

In addition, in the photosensitive drum, the drive transmission part is fixed to the drum flange by a screw that passes through a screw insertion hole formed in the drive transmission part and is fastened to the drum flange in the axial direction of the drive shaft, and the diameter of the screw insertion hole can be made larger than the thread diameter of the screw.

According to the above configuration, the screw passes through the screw insertion hole of the drive transmission part, but the diameter of the screw insertion hole is made larger than the thread diameter of the screw, so the screw does not come into contact with the inner peripheral surface of the screw insertion hole. Therefore, the force acting from the drive transmission part to the drum flange is only a pressure force along the axial direction of the drive shaft, and deflection of the drive transmission part is prevented from being transmitted to the drum flange via the screw.

In addition, in the photosensitive drum, the drive transmission part can be formed as a resin member that is separate from the drive shaft and is fixed to the drive shaft so as to prevent it from rotating.

In addition, in the photosensitive drum, the specified fixing method can be configured to fit a fixing pin arranged in a direction perpendicular to the axial direction of the drive shaft into a groove provided in the drive transmission part.

In order to solve the above problem, the second aspect of the present invention is a method for manufacturing a photoreceptor drum, which is the method for manufacturing a photoreceptor drum described above, characterized in that after the drive shaft is fixed to the drive transmission part, the drive transmission part is fixed to the flange.

In order to solve the above problems, the process unit according to the third aspect of the present invention is a process unit that is detachable from the image forming apparatus and has at least some of the functional parts required for electrophotographic image formation arranged along the rotation direction of the photosensitive drum, and is characterized in that the photosensitive drum is the photosensitive drum described above.

In order to solve the above problems, the image forming apparatus according to the fourth aspect of the present invention is characterized by including the process unit described above.

The photosensitive drum, photosensitive drum manufacturing method, process unit, and image forming device of the present invention transmit the rotation of the drive shaft to the drum flange via the drive transmission section, and even if deflection occurs in the drive transmission section, the deflection can be prevented from being transmitted to the drum flange, thereby achieving the effect of reducing deflection of the drum surface relative to the shaft rotation axis in the photosensitive drum.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing a process unit. FIG. 2 is an exploded view of one end of the photosensitive drum. FIG. 4 is a side view of the drum flange. FIG. FIG. This is a cross-sectional view taken along line AA in FIG. 6. This is a cross-sectional view taken along line B-B of FIG. FIG. 1 is an exploded view of one end of a conventional photoconductor drum. FIG. 11 is a side view of a drum flange in a conventional photoconductor drum. FIG. 1 is a side view of a conventional photoconductor drum. FIG. 13 is an explanatory diagram showing a state in which the position of the pin is misaligned with respect to the outer diameter of the shaft. FIG. 13 is an explanatory diagram showing a state in which the position of the groove is misaligned with respect to the outer diameter of the drum flange.

[First embodiment]
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic diagram showing an example of an image forming apparatus 10 to which the present invention is applied. Note that the image forming apparatus 10 shown in Fig. 1 is a color image forming apparatus having a plurality of process units, but the present invention is not limited to this, and can also be applied to a monochrome image forming apparatus having a single process unit.

As shown in FIG. 1, the image forming device 10 is configured to include a main body 11, a document reading unit 12, a document transport device 13, and a paper feed device 14. The main body 11 has an internal image forming unit for printing an image on recording paper. The document reading unit 12 is disposed above the main body 11, and reads the document when copying the document. In the automatic reading mode, the document transport device 13 transports documents placed on the document set tray sequentially toward the document placement table of the document reading unit 12. The paper feed device 14 stocks recording paper and feeds the recording paper to the main body 11 during image formation.

The image data handled by the image forming device 10 corresponds to a color image using the colors black (K), cyan (C), magenta (M), and yellow (Y), or corresponds to a monochrome image using a single color (e.g., black). For this reason, the image forming device 10 has four process units 20 corresponding to black, cyan, magenta, and yellow. Each process unit 20 forms a toner image corresponding to the image data using electrophotographic technology.

The toner images formed in each process unit 20 are transferred in sequence to the intermediate transfer belt 21 and superimposed. This forms a color toner image on the intermediate transfer belt 21. The color toner image on the intermediate transfer belt 21 is transferred onto a recording sheet, and the fixing device 22 heats and presses the recording sheet to fix the color toner image on the recording sheet.

As shown in FIG. 2, the process unit 20 is configured as a unit that can be attached to and detached from the image forming device 10. Since the process unit 20 forms images using a known electrophotographic method, detailed description will be omitted. However, the process unit 20 is configured such that functional units such as a charging unit, a cleaning unit, and a static electricity removing unit (at least some of the functional units required for image formation using the electrophotographic method) are arranged around the photosensitive drum 100, which is rotatably supported in the image forming device 10, along the direction of rotation of the photosensitive drum 100.

Next, the specific structure of the photoconductor drum 100 will be described. FIG. 3 is an exploded view of one end of the photoconductor drum 100 according to the first embodiment. FIG. 4 is a side view of the drum flange (flange) 120 used in the photoconductor drum 100. FIG. 5 is a side view of the drive transmission plate 140 used in the photoconductor drum 100. However, the side of the photoconductor drum 100 here is merely a name for convenience, and the side of the photoconductor drum 100 does not necessarily coincide with the direction of the side of the image forming device 10 in which it is provided.

The photosensitive drum 100 is roughly composed of a drum base tube 110, a drum flange 120, a shaft (drive shaft) 130, and a drive transmission plate (drive transmission section) 140. The drum base tube 110 is a cylindrical member having an electrophotographic photosensitive body on its surface, and has an aluminum tube on its innermost circumference, around which a photosensitive layer is formed. The drum flange 120 is a resin member that is press-fitted and fixed to both ends of the drum base tube 110 in the axial direction.

The outer shape of the drum flange 120 is formed by a flange portion 121 and a press-in portion 122 that are coaxially formed. The flange portion 121 is formed in a substantially disk shape that is somewhat larger than the outer circumference of the drum base tube 110, and is arranged so as to face the end face of the drum base tube 110 when the drum flange 120 is press-fitted into the drum base tube 110. The drum flange 120 is fixed to the drum base tube 110 by pressing the press-in portion 122 into the inner circumference side of the drum base tube 110. A shaft hole 123 is formed in the center of the drum flange 120, and a shaft 130 is inserted into the shaft hole 123. The shaft 130 is the center of rotation of the drum flange 120 and the drive transmission plate 140, and is arranged to pass through the center of rotation of the drum base tube 110. A coupling gear 131 is fixed to one end of the shaft 130 to receive rotational drive from the main body of the image forming device 10.

The drive transmission plate 140 is a roughly disk-shaped member that is positioned on the outer side (flange portion 121 side) of the drum flange 120 in the axial direction of the drum base tube 110, and has a shaft hole 141 formed in the center, into which the shaft 130 is inserted.

In the photosensitive drum 100 according to the first embodiment, the drum flange 120 is fixed to the shaft 130 in a rotation-preventing manner via the drive transmission plate 140. In other words, the rotational drive force of the shaft 130 is not directly transmitted from the shaft 130 to the drum flange 120, but is transmitted via the drive transmission plate 140, which is fixed to the shaft 130 by a predetermined fixing method. Here, FIG. 6 is a side view showing the outer end surface of the photosensitive drum 100 (coupling gear 131 is not shown). FIG. 7 is a cross-sectional view taken along line A-A in FIG. 6, and FIG. 8 is a cross-sectional view taken along line B-B in FIG. 6.

First, the driving force is transmitted from the shaft 130 to the drive transmission plate 140 by a driving force transmission pin (fixed pin) 150. Specifically, the pin 150 is inserted into the shaft 130, and the drive transmission plate 140 is formed with a groove (groove portion) 142 (see FIG. 5) into which the pin 150 fits. The pin 150 is passed through the shaft 130 so that their axes are perpendicular to each other, and in the photosensitive drum 100, the rotation of the shaft 130 is transmitted to the drive transmission plate 140 via the pin 150 by fitting the pin 150 into the groove 142 (see FIGS. 6 and 7). The pin 150 is also pressed into the groove 142 and fixed so that no play occurs.

Next, the driving force is transmitted from the drive transmission plate 140 to the drum flange 120 by fixing the drive transmission plate 140 to the drum flange 120, more specifically, by pressing the drive transmission plate 140 against the drum flange 120. The use of screws 160 is a suitable method for pressing the drive transmission plate 140 against the drum flange 120. Specifically, screw holes 124 (see Figures 3 and 4) for fastening the screws 160 are provided in multiple locations (at least two locations) in the drum flange 120, and screw insertion holes 143 (see Figures 3 and 5) are provided in multiple locations in the drive transmission plate 140 so as to face the screw holes 124. It is preferable that the multiple screw holes 124 (or the multiple screw insertion holes 143) are arranged at equal angular intervals along the circumferential direction. In addition, the diameter of the screw insertion hole 143 is larger than the thread diameter of the screw 160.

The screw 160 passes through the screw insertion hole 143 of the drive transmission plate 140 and is fastened to the screw hole 124 of the drum flange 120 (see Figs. 6 and 8). At this time, the head of the screw 160 is made larger in diameter than the screw insertion hole 143, and the head of the fastened screw 160 presses the drive transmission plate 140 along the axial direction of the shaft 130, so that the drive transmission plate 140 can be pressed against the drum flange 120. As a result, sufficient frictional force is generated on the pressing surface between the drive transmission plate 140 and the drum flange 120, and the drive force can be transmitted without causing slippage between the drive transmission plate 140 and the drum flange 120. A washer may be placed between the head of the screw 160 and the drive transmission plate 140.

The drive transmission plate 140 is fixed to the shaft 130 by fitting the pin 150 into the groove 142, and the accuracy of the coaxiality of the pin 150 and the groove 142 affects the deflection of the drive transmission plate 140, which may cause a relatively large deflection in the drive transmission plate 140. However, in the configuration of the photosensitive drum 100, the deflection of the drive transmission plate 140 does not affect the deflection of the drum base tube 110. In other words, the photosensitive drum 100 can reduce the deflection of the drum surface relative to the shaft rotation axis. The effect of this is explained as follows.

As described above, the driving force is transmitted from the drive transmission plate 140 to the drum flange 120 by fastening the screw 160 to press the drive transmission plate 140 against the drum flange 120. At this time, the screw 160 passes through the screw insertion hole 143 of the drive transmission plate 140, but since the diameter of the screw insertion hole 143 is larger than the thread diameter of the screw 160, the screw 160 can be prevented from touching the inner peripheral surface of the screw insertion hole 143 (see FIG. 8). Therefore, the force acting from the drive transmission plate 140 to the drum flange 120 is only the pressing force along the axial direction of the shaft 130, and the deflection of the drive transmission plate 140 is not transmitted to the drum flange 120 via the screw 160.

In other words, although the coaxiality accuracy of the pin 150 and the groove 142 may affect the deflection of the drive transmission plate 140, it does not affect the deflection of the drum flange 120 and the drum base tube 110. As a result, the coaxiality accuracy of the drum surface of the photosensitive drum 100 can be ensured to be high by eliminating the effect of the coaxiality accuracy of the pin 150 and the groove 142, and the photosensitive drum 100 can reduce the deflection of the drum surface relative to the shaft rotation axis.

The above-mentioned drive transmission configuration (drive transmission configuration via the drive transmission plate 140) may be provided at one end of the photosensitive drum 100, and in this case, it is preferable that it is provided on the drive input side of the shaft 130 (the side where the coupling gear 131 is arranged). In addition, the manufacturing procedure for the photosensitive drum 100 is preferably such that the shaft 130 is fixed to the drive transmission plate 140, and then the drive transmission plate 140 is fixed to the drum flange 120.

Second Embodiment
In the above-described first embodiment, a configuration has been exemplified in which the drive transmission plate 140 is fixed to the shaft 130 in a rotation-preventing manner (predetermined fixing method) by fitting the drive transmission plate 140 into the groove 142 of the pin 150. However, the present invention is not limited to this, and the drive transmission plate 140 may be fixed to the shaft 130 in a rotation-preventing manner by a D-cut. That is, the cross section of the shaft of a part of the shaft 130 may be machined into a D shape, and the shaft hole 141 in the drive transmission plate 140 may be formed into a similar D shape.

Third Embodiment
In the above-mentioned first and second embodiments, the drive transmission plate 140 is a separate member from the shaft 130. Making the drive transmission plate 140 a separate member from the shaft 130 has the advantage that each member can be molded using an appropriate material (e.g., the drive transmission plate 140 is made of resin and the shaft 130 is made of metal) and processing method, which is advantageous in terms of cost, and the assembly of the photoconductor drum 100 and the replacement of parts are facilitated. However, the present invention is not limited to this, and the drive transmission plate 140 may be any member that can rotate integrally with the shaft 130, and the drive transmission plate 140 and the shaft 130 may be integrally formed from the same material (e.g., metal).

In addition, in the above-mentioned first and second embodiments, a configuration is exemplified in which the screw 160 is used to press the drive transmission plate 140 against the drum flange 120, but it is also possible to use a press-in pin (which does not have a threaded portion and has a pin head equivalent to the screw head of the screw 160) instead of the screw 160 as long as it can press the drive transmission plate 140 against the drum flange 120.

The embodiments disclosed herein are illustrative in all respects and are not intended to be a basis for a restrictive interpretation. Therefore, the technical scope of the present invention is not to be interpreted solely by the above-described embodiments, but is defined based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

10 Image forming apparatus 20 Process unit 100 Photoconductor drum 110 Drum base tube 120 Drum flange (flange)
121 Flange portion 122 Press-fit portion 123 Shaft hole 124 Screw hole 130 Shaft (drive shaft)
131 Coupling gear 140 Drive transmission plate (drive transmission section)
141 Shaft hole 142 Groove (groove portion)
143 Screw insertion hole 150 Pin (fixing pin)
160 bis

Claims (5)

In a rotatably supported photoconductor drum used in an image forming apparatus,
a cylindrical drum tube having an electrophotographic photosensitive member on its surface;
Flanges are press-fitted and fixed to both axial ends of the drum blank;
a drive transmission section provided further outside the flange in the axial direction of the drum base tube;
a cylindrical drive shaft which is a rotation center of the flange and the drive transmission unit and which passes through a rotation center of the drum base;
A fixing pin is inserted through the drive shaft so that their axes are perpendicular to each other;
Equipped with
the flange has a flange-side shaft hole into which the drive shaft is inserted so as to abut,
the drive transmission portion has a drive transmission portion-side shaft hole into which the drive shaft is inserted so as to abut, a groove portion into which the fixing pin is fitted, and a screw insertion hole formed in the axial direction of the drive shaft,
the drive transmission portion is fixed to the flange by a screw that penetrates the screw insertion hole and is fastened to the flange in an axial direction of the drive shaft,
The diameter of the screw insertion hole is larger than the thread diameter of the screw,
The photosensitive drum according to claim 1, wherein the drive shaft is fixed to the drive transmission portion without play by press-fitting the fixing pin into the groove . 2. The photoconductor drum according to claim 1 ,
The photosensitive drum is characterized in that the drive transmission portion is formed as a resin member separate from the drive shaft. 3. A method for manufacturing the photoconductor drum according to claim 1, comprising the steps of:
a drive shaft fixed to the drive transmission part, and then the drive transmission part is fixed to the flange, A process unit that is detachably attached to an image forming apparatus and has at least some functional units required for electrophotographic image formation arranged along a rotation direction of a photosensitive drum,
3. A process unit, wherein the photoconductor drum is the photoconductor drum according to claim 1 . An image forming apparatus comprising the process unit according to claim 4 .

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