JPH10187007A - Image forming unit for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming unit for image forming device capable of preventing the occurrence of an abnormal image caused by the collision of an electrifying roller with a photoreceptor, by preventing an electrifying roller case from moving up and down in the image forming unit even when the image forming unit is vibrated or receive shock by dropping at the time of being carried. SOLUTION: This image forming unit is constituted by housing an electrifying device equipped with the electrifying roller 19 electrifying the photoreceptor 18 while rotating following the photoreceptor 18 coming into contact with the photoreceptor and the electrifying roller case 31 holding the roller 19, the photoreceptor 18 and a developing device in a single case. The unit is provided with a fixed member 60 preventing the roller 19 from colliding with the photoreceptor because the case 31 is moved up and down by the vibration and the impact at the time of dropping.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
Regarding image forming apparatuses such as printers and facsimile machines,
In particular, the present invention relates to an image forming apparatus having an image forming unit in which a photoconductor, a developing device, a charging device, and the like are housed in a single case, and the entire image forming unit can be replaced. More specifically, it is possible to prevent a charging roller incorporated in the image forming unit for charging the photosensitive member from colliding with and pressing against the photosensitive member due to an impact when the image forming unit is transported, thereby causing various problems. The present invention relates to an image forming unit that can be used.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine or a facsimile, an image forming unit is formed by housing a photosensitive member, a developing device, a charging device, and the like in an integrated case. By making the unit detachable in units, the size of the entire image forming apparatus is reduced. The charging device incorporated in such an image forming unit is often of a charging roller type that uniformly charges to a constant potential by attaching ions or electrons to the surface of the photoconductor using a charging roller. FIG. 9 is a diagram showing a conventional configuration (unknown) of a charging device and a photoconductor of this type. In order to hold the charging roller 1 in the charging roller case 2, the charging device 1 A spring 4 is provided between the bearing 3 that supports the shaft end and the lower surface of the charging roller case 2.
4 to support the charging roller 1,
The entire charging device including the case 2 and the spring 4 is supported to be vertically movable toward the surface of the photoconductor. Further, when the charging roller 1 comes into contact with the photoconductor 5 by pushing down the entire charging device toward the photoconductor by a rotating arm or the like (not shown), the charging roller 1 is biased by the spring 4.
Is uniformly pressed against the photoreceptor 5 to rotate with the photoreceptor 5 to uniformly charge the surface of the photoreceptor 5. A cleaning pad 6 made of a sponge or the like is adhered to the lower surface of the charging roller case 2. In order to clean the charging roller surface during a non-image forming process, the charging roller 1 is attached to the photosensitive member 5 by an arm (not shown). The charging roller case 2 is further pressed down from the above-mentioned state, and the cleaning pad 6 is brought into strong contact with the charging roller 1. The toner and other foreign matter are removed from the surface. As described above, an image forming unit having a mechanism for preventing the photosensitive member from being stained by bringing the charging roller into and out of contact with the photosensitive member by constantly contacting the photosensitive member is not known. When such a contact / separation mechanism is provided, when the image forming unit is transported alone or with the image forming apparatus, the charging roller collides with the photosensitive member due to vibration, impact, etc. Since a defect occurs, it is necessary to improve this point.

[0003]

More specifically, in an image forming apparatus using an image forming unit having the above-described configuration, downsizing is an important issue. In many cases, only a minimum clearance required for functioning as an image forming apparatus is allowed as a space between components such as a photoconductor, a charging device, and a developing device. Also in the image forming unit shown in FIG.
When the charging roller 1 is separated from the photoreceptor 5 during non-image formation, the clearance between them is only about 2 mm. In such an image forming unit, when the image forming unit alone or an impact due to vibration or drop during transportation of the image forming apparatus is received, the charging roller case 2 moves up and down in the image forming unit, and the charging roller 1 is moved to the photosensitive member. 5 may collide. In such a case, a shock that is impossible during a normal image forming operation is applied to the photoconductor from the charging roller, so that the rubber component of the charging roller adheres to the surface of the photoconductor, and dent marks and scratches are generated on the surface of the photoconductor. Or an abnormal image. The present invention has been made in view of the above, and even when the image forming unit is subjected to vibration and impact due to dropping, the charging roller case does not move up and down in the image forming unit, and the charging roller is exposed to light. It is an object of the present invention to provide an image forming unit of an image forming apparatus capable of preventing occurrence of an abnormal image due to collision with a body.

[0004]

Means for Solving the Problems To achieve the above object, an invention according to claim 1 is a charging roller for charging a photosensitive member while being driven to rotate while being pressed against a photosensitive member, and a charging roller for holding the charging roller. In an image forming unit in which a charging device having a case, a photoconductor, and a developing device are housed in a single case, the charging roller case moves up and down due to vibration and impact at the time of falling, and the charging roller is exposed to light. It is characterized in that a fixing member for preventing collision with the body is provided. The invention according to claim 2 is characterized in that the fixing member is configured to be detachable from the image forming unit. According to a third aspect of the present invention, there is provided a charging device including a charging roller configured to charge the photosensitive member while being rotated while being pressed against the photosensitive member, a charging roller case holding the charging roller, a photosensitive member, and a developing device. In a single case, a buffer member is detachably disposed between the charging roller and the photoconductor.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming unit of an image forming apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of an image forming unit using the charging device according to the present invention, and FIG. 2 is a sectional view showing the image forming unit, the transfer / separation device, the fixing device, and the like in FIG. First, the configuration of an image forming unit of an image forming apparatus using an embodiment of the charging device of the present invention will be described with reference to these drawings. In these drawings, reference numeral 10 denotes an image forming unit, 11 denotes a transfer / separation device, and 12 denotes a fixing device.
Is formed in a cartridge shape and is detachable from an image forming apparatus main body (not shown). Further, the transfer / separation device 11 includes a transfer roller 13 and is rotatable in a vertical direction in FIG.
Is composed of a pressure roller 15 and a heating roller 16. The illustrated image forming unit 10 comprises a case made of a photosensitive member surrounding case 17 and an upper cover 37 made of a synthetic resin, and a photosensitive member 18, a charging roller 19 constituting a charging device, a developing device 20, a cleaning device The image forming apparatus includes a toner recycle belt 22, a toner conveying screw 42, a developer agitating member 43, and the like for feeding the residual toner collected by the device 21 and the cleaning device 21 to the developing device 11. The upper cover 37 is attached so as to cover the case 17 around the photoconductor, thereby preventing the hand of an operator or a service person from contacting the photoconductor 18 and the charging roller 19.

As shown in an exploded perspective view of FIG. 3, a charging roller 19 of the charging device is provided on the outer periphery of a metal core 27 with a roller-shaped conductive rubber (having a small hygroscopic property and a stable resistance value). By applying a high voltage to the metal core 27 while the surface of the conductive rubber 28 is in contact with the surface of the drum-shaped photoreceptor 18, the photoreceptor 18 is fixed. Is uniformly charged. Both ends of the core metal 27 of the charging roller 19 are
29, each bearing 29 is rotatably supported by a charging roller case 31, and a pressure spring 33 is interposed between the bearing 29 and the inner surface of the charging roller case 31. The urging force of the pressure spring 33 allows the charging roller 19 to be pressed against the photoreceptor 18 with a predetermined pressure. The structure in which the bearing 29 is vertically movably supported by the case 31 is as follows.
For example, the guided projection 29 protruding from both ends of the bearing 29
a is vertically movably supported by a long hole (or groove) 31 a provided in the case 31.

A cleaning pad 34 for cleaning the surface of the charging roller 19 is attached to the lower surface of the charging roller case 31, which is a holding member of the charging roller 19, with an adhesive such as a double-sided tape. The charging roller 19 keeps in contact with the surface of the photoconductor 18 during the charging operation. As is well known, the surface of the charging roller 19 is easily stained by minute toner adhering to the surface of the photoreceptor 18 to cause uneven charging. However, the cleaning is performed by pressing the cleaning pad 34 against the surface of the charging roller. The charging roller 19 is removed by removing the toner
Can be prevented from being unevenly charged when the surface becomes dirty. Further, a spring 3 is provided between the inside of both ends in the longitudinal direction of the charging roller case 31 and the spring receivers 35 provided on the photosensitive member surrounding case 17 of the image forming unit 10.
6 and 36, the charging roller case 31 is pushed upward in the figure by the urging force of the spring 36 so as to separate the entire charging device from the photoreceptor 18 except during the charging operation and the cleaning of the charging roller 19. Energize (push up).

Reference numerals 40 and 40 in FIG.
Are a pair of swingable pressure arms which constitute a contact / separation mechanism for bringing the photosensitive member 18 into and out of contact with the photosensitive member 18. 1 and 4, 5
As shown in FIG. 5, the two arms 40 are connected by a rotating shaft 99 so as to be rotatably supported on the image forming apparatus main body side (not shown) and to have an outer periphery of the eccentric cam 100 on one end 40 a of one arm 40. The arms 40 can be rotated about the rotation shaft 99 by bringing the surfaces into contact with each other and rotating the eccentric cam 100 by a required angle by a driving means such as an electromagnetic clutch. And arm 4
0 at the end of the charging roller case 31 (the hole 3 of the upper case 37).
7A, the upper surface of which is partially exposed) is pressed to charge the charging roller 19 together with the charging roller case 31.
Is pressed toward the photoreceptor 18 side. When the pressure arm 40 is separated from the upper surface of the charging roller case 31, the charging roller 19 and the charging roller case 31 are separated from the photosensitive member 18 by the urging force of the spring 36. In the figure, 10
Reference numeral 1 denotes a holder for a static elimination lamp (not shown), which is made of a highly rigid metal or the like, and is fixed to the distal end side of the arm 40 in parallel with the rotation shaft 99.

An image forming operation using the image forming unit having such a configuration will be briefly described. First, with the image forming apparatus main body mounted in a predetermined position, the photosensitive member 18 is rotatable in the direction of the arrow in FIG. 2 by a driving source (not shown). A neutralizing lamp is irradiated with neutralizing light to neutralize the surface, and the surface potential is averaged to a reference potential of, for example, 0 to -150V. Next, a high voltage is applied to the charging roller 19 in contact with the surface of the photoreceptor 18 to charge the photoreceptor 18, and the surface potential is set to, for example, about -1100V. Then, the charged potential surface is exposed to form a latent image portion having an image surface potential of, for example, 0 to -290 V. When the latent image portion is moved to the position of the developing sleeve 23 of the developing device 20 by the rotation of the photoreceptor 18, the developing sleeve 2 in which a bias of about -800 V is applied to the latent image portion, for example.
The toner held on the surface of No. 3 adheres, and the latent image portion is developed to become a toner image (visible image).

On the other hand, the transfer paper P supplied from a paper supply unit (not shown) is moved by the registration roller pair 24 so that the front end of the transfer paper P and the front end of the toner image on the photoreceptor 18 coincide with each other at the position of the transfer roller 13. The timing is adjusted, and the toner image on the photoconductor 18 is transferred to the transfer paper P by the transfer roller 13. The transfer paper P is conveyed between the pressure roller 15 and the heating roller 16 of the fixing device 12, where the transferred toner is fused to the transfer paper P by heat and pressure, and is transferred to a discharge tray (not shown) outside the apparatus. Discharge. The residual toner remaining on the photoreceptor 18 after the image transfer is scraped off by the cleaning blade 25 of the cleaning device 21, and the process proceeds to the next image forming step in a state where almost no toner adheres to the surface of the photoreceptor 18 and remains. The residual toner collected by the cleaning device 21 is transferred to the developing device 2 by the toner recycling belt 22.
0 and is collected by transporting the developer to the developer agitating section 26.
Then, the toner is agitated at 3 and supplied to the developing sleeve 23 again to recycle the toner. In the drawing, reference numeral 41 denotes a holder for the cleaning blade 25.

FIGS. 6 (a), 6 (b) and 6 (c) are views showing the operation and the positional relationship between the charging roller 19, the charging roller case 31 and the arm 40 during each operation of the image forming unit as described above. First, when the photosensitive member 18 is not charged as shown in FIG. 6 (a), the arm 40 is rotated to the uppermost position by the eccentric cam 100, and the charging roller 19 is turned off.
The charging roller case 31 is pushed up by the spring 36 and is separated from the surface of the photoconductor 18. Next, in a charging mode for charging the photosensitive member 18 shown in FIG. 6B, the arm 40 is rotated downward by the eccentric cam 100, and the charging roller case 31 is biased by the spring 36. Roller 1 is pressed down against
9 contacts the surface of the photoreceptor 18 with a predetermined pressing force by the urging force of the spring 33 and rotates together with the photoreceptor 18.
In this state, the surface of the photoconductor 18 is charged. Further FIG.
In a cleaning mode for cleaning the surface of the charging roller 19 shown in FIG.
0, the charging roller 19 is rotated to the lowermost position, the charging roller 19 is strongly pressed against the surface of the photoconductor 18, and the cleaning pad 34 comes into contact with the surface of the charging roller 19 so as to cut into the surface, and accompanies the photoconductor 18. The toner and the like are cleaned and removed by sliding contact with the surface of the rotating charging roller 19. Each of the above-described modes corresponds to the eccentric cam 1
It is repeated alternately according to the change of the cam curve of 00.

By the way, as shown in FIGS. 7 (a) and 7 (b), the characteristic structure of the apparatus according to the present embodiment is as follows.
When the charging roller case 31 is fixed, the front side and the back side are fixed by two fixing members 60 and 60, respectively, so that the charging roller case 31 does not move up and down in the image forming unit 10. . The upper cover 37 has a hole 37A on the upper surface, and a part of the case 31 is viewed through the hole 37A. The fixing member 60 is made of a leaf spring made of resin, metal, or the like, and includes a right end portion 60a, a central portion 60b,
Left end 60c and claw 60d extending downward from a suitable position in the center
Having. The fixing member 60 is disposed at a position avoiding the position at which the arm 40 contacts. As a method for attaching the fixing member 60, as shown in the cross-sectional view of FIG.
The right end 60a of the fixing member 60 is grasped by hand, the claw of the left end 60c is hooked into the recess 37B of the upper cover 37, and the claw 60d is extended downward from the center when the claw is lowered downward. The case 31 is elastically hooked. At the time of removal, the center portion 60b, the left end portion 60c and the claw 60d are successively disengaged simply by pulling up the right end portion 60a in the lifting direction. When transportation is completed,
By removing the fixing member 60, the apparatus main body can function normally.

FIGS. 8 (a) and 8 (b) are views showing another embodiment of the present invention, that is, an embodiment of claim 3, wherein FIG.
1 is an external perspective view, and FIG. The feature of this embodiment is that the cushioning members 61 are made of an elastic material or the like.
Is inserted into a non-image area between the charging roller 19 and the photoconductor 18 at two positions, a front side and a rear side, of the image forming unit 10 to prevent the charging roller 19 from contacting the photoconductor 18. . Attachment and removal of each cushioning member 61 are easy, and the left end 6 of the cushioning member 61 in the sectional view of FIG.
1a, which is to be inserted and attached, removed and removed. The left end 61a is made of, for example, cardboard, and the buffer member body is made of styrene foam, sponge, or the like. This cushioning member may be used together with the fixing member 60 or may be used alone.

[0014]

As described above, according to the first aspect of the present invention, the case for supporting the charging roller is fixed by the fixing member when transporting the image forming unit. However, the charging roller case can be moved up and down in the image forming unit due to the impact of the vibration and dropping during transportation of the image forming unit, and the charging roller can be prevented from hitting the photosensitive member, and the charging roller hits the photosensitive member The occurrence of an abnormal image due to a flaw on the surface of the photoreceptor caused by the above can also be prevented. According to the second aspect of the present invention, in addition to the same effects as those of the first aspect, the attachment and detachment of the fixing member can be easily performed, so that the load at the time of assembling is small and the user or the service person can use the image forming unit in the market. There is also an effect that the unpacking operation can be easily performed when replacing. According to the third aspect of the present invention, since the buffer member is disposed between the charging roller and the photoconductor, the same effects as those of the first and second aspects can be obtained without using a fixing member. .

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an image forming unit using a charging device according to the present invention.

FIG. 2 is a cross-sectional view illustrating an image forming unit, a transfer / separation device, a fixing device, and the like in FIG.

FIG. 3 is an exploded perspective view of a main part of FIG. 1;

FIG. 4 is a plan view showing a configuration of a pressure arm.

FIG. 5 is a front view of FIG. 4;

FIGS. 6 (a), (b) and (c) are explanatory views of the operation of the pressure arm.

FIGS. 7A and 7B are explanatory views of a fixing member which is a characteristic configuration of the present invention.

8 (a) and 8 (b) are explanatory views of another embodiment of the present invention.

FIG. 9 is an explanatory view of a conventional example.

[Explanation of symbols]

Reference Signs List 10 image forming unit, 11 transfer / separation device, 12 fixing device, 13 transfer roller, 14 rotation fulcrum, 17 case around photoconductor, 18 photoconductor, 19 charging roller, 2
0 developing device, 21 cleaning device, 40 arm, 31 charging roller case, 33 pressure spring,
34 cleaning pad, 60 fixing member, 61 cushioning member.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeru Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Toshitaka Yamaguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Kenzo Tatsumi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Hiroshi Yoshinaga 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company ( 72) Inventor Takeo Suda 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Mayumi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company

Claims (3)

[Claims] A charging device including a charging roller for charging the photosensitive member while being rotated while being pressed against the photosensitive member, a charging device including a charging roller case for holding the charging roller, a photosensitive member, and a developing device. In the image forming unit housed in one case, there is provided an image, wherein a fixing member is provided for preventing the charging roller case from moving up and down due to vibration and impact at the time of dropping, thereby preventing the charging roller from hitting the photosensitive member. An image forming unit of the forming apparatus. 2. The image forming unit according to claim 1, wherein the fixing member is configured to be detachable from the image forming unit. 3. A charging device comprising: a charging roller for charging the photosensitive member while being rotated while being pressed against the photosensitive member; a charging device including a charging roller case for holding the charging roller; a photosensitive member; and a developing device. An image forming unit for an image forming apparatus, wherein a buffer member is detachably disposed between the charging roller and the photosensitive member.