JPH0421874B2 - - Google Patents

Description

Detailed Description of the Invention <Technical Field of the Invention> The present invention relates to an improvement in an electrophotographic copying apparatus using an endless sheet-like photoreceptor, and more particularly, to an improvement in an electrophotographic copying apparatus using an endless sheet-like photoreceptor along a predetermined path. The present invention relates to an electrophotographic copying apparatus in which an improved positioning for inserting a sheet-like photoreceptor into a drum unit movably supported by a drum unit. <Technical Background of the Invention and its Problems> A conventional electrophotographic copying apparatus using an endless sheet-like photoreceptor is disclosed in, for example, Japanese Patent Laid-Open No. 55-93184. In such conventional electrophotographic copying devices that use an endless sheet-like photoreceptor, copying quality deteriorates due to deterioration of the characteristics of the sheet-like photoreceptor used, life span, etc. The sheet photoconductor is replaced every time a new photoconductor is inserted, but the operator only has to check whether the new photoconductor has been inserted into the correct position. When replacing a new sheet-like photoconductor, if the sheet-like photoconductor replacement work is completed without inserting the photoconductor to its normal position, it will not be possible to make copies by the amount that the sheet-like photoconductor has been inserted into. In addition, in those in which a sheet-like photoreceptor is provided with holes for process control, there is a problem that a signal failure for process control occurs. <Object of the Invention> The present invention has been accomplished with the object of providing an electrophotographic copying apparatus equipped with a novel sheet-like photoreceptor insertion and positioning mechanism that eliminates the above-mentioned conventional problems. To achieve this, the electrophotographic copying apparatus of the present invention includes a drum unit that movably supports an endless sheet-like photoreceptor along a predetermined path, and a rotatable drum unit that is positioned in front of the drum unit. and a photoreceptor positioning member provided in the drum unit, and the endless sheet-like photoreceptor inserted into the drum unit by the photoreceptor positioning member according to the rotational movement of the photoreceptor positioning member. It is configured to be set at a predetermined insertion position. <Embodiment of the Invention> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing the overall content structure of a specific example of an electrophotographic copying apparatus in which the present invention is implemented. In FIG. 1, reference numeral 1 denotes a document table which is movably provided on the main body of the copying machine and holds the document, 2 is an illumination device that illuminates the document on the document table 1, and 3 is a rotary conveyance device for transmitting reflected light from the document. This optical means includes a self-occurring lens and the like that projects the image onto the photoreceptor 4. The photoreceptor 4 is formed into an endless sheet, as will be described later, and a corona discharger 5, which has been previously provided opposite the photoreceptor 4, is formed by an image projection (exposure) process by the optical means 3. The photoreceptor 4 is uniformly charged with a specific polarity, and by imagewise exposure to the photoreceptor 4, an electrostatic latent image corresponding to the original to be copied is formed on the photoreceptor 4. This latent image is then developed in a developing/cleaning device 6 provided, and toner is attached thereto. Incidentally, a cartridge 7 for replenishing toner is attached to the developing/cleaning device 6. Further, a cassette 8 containing a large number of sheets of paper is removably installed in the main body of the photographic apparatus, and a paper feed roller 9 is provided opposite to the sheets of the cassette. The paper feed roller 9 is driven in response to a paper feed signal from a control means (not shown) for controlling copying of the copying apparatus, and the paper in the cassette 8 is fed one by one. This paper feed is sent to a conveyance roller 10 and a conveyance timing control board 11,
The transport timing control plate 11 transports the paper to the transfer process in synchronization with the rotational position of the photoreceptor 4 so that the leading edge of the image on the photoreceptor 4 and the leading edge of the paper coincide in the transfer process. A corona discharger 12 that performs corona discharge from the back side of the paper is disposed facing the photoreceptor 4 at a position where the paper is fed (transfer position) coinciding with the image forming tip on the photoreceptor 4. Through this transfer process, the toner image formed on the photoreceptor 4 is transferred onto the paper, and the paper supporting the toner image is peeled off from the photoreceptor 4 and moved to a fixing roller disposed in a direction away from the photoreceptor 4. 13
After the toner image is fixed, the paper is discharged from the apparatus. On the other hand, a static eliminator 14 and a static eliminator 15 are provided behind the transfer process position to face the photoreceptor 4, and the photoreceptor 4 is charged at the second stage after the transfer process after the static electricity is removed.
At the rotation point, the toner remaining on the surface is cleaned by facing the developing/cleaning device 6 and prepared for the next image formation. This photoreceptor 4 is different from a normal cylindrical drum formed or supported by a large-diameter drive roller (large-diameter drum) 1 that constitutes a drum unit.
An endless sheet-like photoreceptor is held between the roller 6 and a small-diameter roller (small-diameter drum) 17 under tension. The drive roller 16 is fixed at a fixed position with respect to the main body of the copying apparatus, and is rotated by the rotational force of the drive means (main motor 18). Further, although the roller 17 provided opposite to the drive roller 16 is normally rotatably held at the position shown in the figure, it is configured to be moved in the direction of the arrow when the photoconductor 4 is replaced, as will be described later. be. Therefore, by moving the roller 17 in the direction of the arrow, the tension state of the photoreceptor 4 held between the rollers 16 and 17 is released, and the photoreceptor 4 can be easily replaced. In particular, the photoreceptor 4 is formed into an endless shape by fixing the front and rear ends of the sheet-like photoreceptor with fixtures 19, as shown in FIG. Such a photoreceptor is deformable to some extent, and since the photoreceptor 4 has an endless shape, it is very easy to take out the photoreceptor 4 or insert it between the rollers 16 and 17, and after insertion, When the roller 17 is returned to its normal position, a suitable tension is applied to the photoreceptor 4 itself.
For example, the photoreceptor 4 is brought into close contact with the drive roller 16 without being lifted up. Of course, as shown in FIG. 2, the front and rear ends of the photoreceptor 4 may not be connected, but may be endless, or the connecting portion may have a non-image forming portion. FIG. 3 is an external perspective view showing the open state of the copying apparatus embodying the present invention, which is structured to be able to be divided into a first main body and a second main body, and is configured to be openable and closable. In FIG. 3, an upper frame unit 21 constituting the first main body is rotatable about a shaft 22.
It is pivotally supported by a lower frame unit 23 constituting the main body, and is held in the open position shown in FIG. 3 by a spring (not shown) or the like. On the first main body side, there is a drum unit equipped with a document table 1, an illumination device 2, an optical means 3, a corona discharger 5, a developing/cleaning device 6, a cartridge 7, a static eliminator 14, a static eliminator 15, and a photoreceptor 4. A cassette 8, a paper feed roller 9, a transport roller 10, a transport timing control plate 11, a corona discharger 12, a fixing roller 13, and a paper discharge tray 25 are provided on the second main body side. The first main body and the second main body are configured to be openable along the paper conveyance path. Reference numeral 26 denotes a protective cover for the drum unit 24 , and this drum unit protective cover 26 is rotatably supported by a protrusion provided at the lower part of the opening 28 of the upper frame unit 21 . 27 again
is the front cabinet opening/closing lid of the main body of the copying machine;
This opening/closing lid 27 is rotatably supported on the upper part of the lower frame unit 23 . According to the embodiment of the present invention, when replacing the endless sheet-like photoreceptor 4 (master M), first open/close the front cabinet cover 2 of the main body of the copying apparatus.
7, open the upper frame unit 21 and lower frame unit 23 vertically, rotate the tension release lever 31 clockwise about the shaft 32 as shown in FIG. Move it to position b. By this operation, the tension state of the photoreceptor 4 is released, as will be described later. Next, grasp the lock release lever 33 provided on the upper outer side of the drum unit protective cover 26 and pull it toward you to release the photoreceptor 4.
Open the drum unit protective cover 26 for preventing pre-exposure of (Master M) (at this time, the apparatus is in the state shown in FIG. 3). The drum unit protective cover 26 also protects the photoconductor 4.
The structure is such that it cannot be opened unless the tension state is released. That is, photoreceptor 4 (master M)
If the tension acting on is not released,
The tension release lever 31 is in the state a (see FIG. 4), and in this state, the tip 31-a of the tension release lever 31 is in the state shown in FIG. As shown in FIG. 4 (a cross-sectional view), the drum unit protection cover 26 is engaged to prevent the drum unit protection cover 26 from opening. Therefore, when the drum unit protective cover 26 is opened, the tension state of the photoreceptor 4 is released, and the old photoreceptor (master M) is pulled out from the opening 28 of the upper frame unit 21.
The photoreceptor 4 will be replaced by inserting a new endless photoreceptor 4 (master M). Further, as an embodiment of the present invention, a photoreceptor positioning member 35 is provided at the lower part of the back surface of the drum unit protective cover 26 at a position facing the side edge of the photoreceptor 4 when the cover 26 is closed.
Therefore, when the drum unit protective cover 26 that has been opened after replacing the old and new photoconductor 4 is closed, the drum unit protective cover 26 will be closed even if the new photoconductor 4 is not inserted into the normal position. Photoreceptor positioning member 3 provided on the back surface
5, the photoreceptor 4 is pushed in the insertion direction, and the photoreceptor 4 is inserted and set at a regular position. That is, when the drum unit protective cover 26 is closed by rotating it around the shaft 36 in the direction of arrow D as shown in FIG. The photoreceptor positioning members 35 provided to face each other move in the direction of arrow C, and even if the photoreceptor 4 is not inserted into the normal position, the photoreceptor 4 is moved by the photoreceptor positioning members 35. Photoconductor 4 is pushed in the direction of arrow C.
is inserted and positioned at a predetermined position. Note that if the tension release lever 31 is returned from position b to position a before closing the drum unit protective cover 26, the drum unit protective cover 26
is in a state where it cannot be closed. That is, before closing the drum unit protective cover 26, rotate the tension release lever 31 counterclockwise from position b to position a.
When the drum unit protective cover 26 is closed after the tension release lever 31 is moved to the position shown in FIG.
This configuration prevents the photoreceptor 4 from being closed.
5, if tension is applied to the photoconductor 4, the photoconductor 4 will not be inserted into the normal position and will remain in that position with the insertion position shifted, resulting in defects on the copied image. This is only possible when the inconvenience that occurs is prevented and the tension release lever 31 is at position b, in other words, when no tension is acting on the photoreceptor 4 and the photoreceptor 4 is movable in the insertion direction. , the drum unit protective cover 26 can be closed. Further, as the photoreceptor positioning member 35 that functions as described above, it is suitable to use, for example, polyethylene terephthalate (PET) with a thickness of about 0.2 mm. With the tension release lever 31 in position b, the drum unit protective cover 26 is closed, and then the tension release lever 31 is rotated back from position b to position a to apply tension to the photoreceptor 4.
Next, the upper frame unit 21 is pushed down to integrate with the lower frame unit 23 , and the front cabinet opening/closing lid 27 is closed to complete the replacement of the photoconductor 4. According to this embodiment, the drum unit protective cover 26 Even if you forget to close the photoconductor 4 or apply tension to the photoreceptor 4 using the tension release lever 31, the upper frame unit 21 can be automatically released by pushing down and combining with the lower frame unit 23 . Close the drum unit protective cover 26, and then move the tension release lever 31 from position b (tension released state) to position a (tension applied state).
It is configured so that it can be rotated back. The specific structure will be explained below. As shown in FIG. 8, a pressing member 41 is provided upright on the lower frame unit 23 in correspondence with the drum unit protective cover 26.
An inclined portion 41-a is formed at the upper end portion of 1. When the upper frame unit 21 is pushed down in the direction of the arrow with the drum unit protection cover 26 open (FIG. 8) and closed, the inclined portion 26 of the drum unit protection cover 26 will open as shown in FIG.
The inclined portion 41-a of the pressing member 41 contacts and presses the drum unit protective cover 26, and then the vertical portion 41-b of the pressing member 41 reliably presses it in the direction of the arrow E. The drum unit protective cover 26 is closed before the frame unit 21 is completely closed (FIG. 10). At this time, the lock portion 33-a of the release lever 33 provided on the protective cover 26 is fitted into the lock hole 42 provided on the drum unit 24 and locked, as shown in FIG. The lock release lever 33 is rotatably attached to the drum unit protective cover 26 about a shaft 43, and a force is applied in the direction of arrow F by a spring pressing member 33-b. In this way, the drum unit protective cover 26 is always locked by the lock release lever 33 as shown in FIG.
The lock is locked in the closed state by the lock release lever 33, and the lock is not released unless the lock release lever 33 is pushed down and rotated counterclockwise. Therefore, by pushing down the lock release lever 33 to remove the lock hole 42 formed in the drum unit 24 , and then pulling it toward you, the drum unit protective cover 26 can be removed.
will be released. Next, a configuration for applying and releasing tension to the photoreceptor 4 will be described with reference to FIGS. 12 and 13. In this example, as a method for applying and releasing tension on the photoreceptor 4, a large diameter drum (large diameter drive roller) 16 is used.
This is done by changing the distance between the axes of the small diameter drum (small diameter roller) 17, and FIG. 12 is a perspective view showing an example thereof. The large diameter drum 16 is held at a fixed position on the upper frame unit 21 , as will be described later. On the other hand, the other end of the rotating shaft 51 (not shown) of the small diameter roller 17 is slidably supported through an elongated hole as will be described later. Further, the tip of a rotating shaft 51 shown in FIG. 12 is rotatably attached to a tension plate 52. The tension plate 52 has an L-shaped deformed elongated hole 53 as shown in the figure.
is formed, and one end of a shaft 54 passes through this elongated hole 53. Also, the tension plate 52
is provided with a pin 55, and a spring 57 is installed between the pin 55 and a hook plate 56 attached to the side plate of the drum unit 24 to apply tension from the small diameter drum 17. This spring 57 urges the tension plate 52 in the direction of arrow G in the state shown in FIG.
The small diameter drum 17 serves to provide tension. A connecting plate 5 is attached to the tip of the shaft 54 passing through the deformed elongated hole 53 of the tension plate 52.
8 is fixed, and the tension release lever 31 is
They are attached to the tip of the shaft 54 in the relationship shown in the figure. Further, a guide pin 59 passing through the L-shaped hole 53 of the tension plate 52 is fixed to the connecting plate 58. Also, the tension release lever 31 of the above-mentioned members
A configuration other than this is provided on the other end side of the drum 17. In the structure as described above, when removing the endless photoreceptor 4 from between the drums 16 and 17, as shown in FIG.
When is rotated in the direction of arrow H, the connecting plate 58 fixed to the shaft 54 rotates around the shaft 54. At this time, the tension plate 52 is attached to the guide pin 59.
14, the L-shaped hole 53 moves to the right in the figure while being guided by the shaft 54, and is held in the state shown in FIG. Note that the amount of movement of the small diameter drum 17 at this time is the distance x between the shaft 54 and the guide pin 59. In this way, the tension plate 52 is
moves to the right using the guide pin 59 and the deformed elongated hole 53 as guides, and the large diameter drum 16 and the small diameter drum 1
The distance between the axes 7 and 7 is reduced, and the tension on the photoreceptor 4 is released. The endless photoreceptor 4 inserted between the drums 16 and 17 in the state shown in FIG. 14 above can be easily taken out, and a new endless photoreceptor 4
is inserted between the drums 16 and 17 to replace the photoreceptor 4. After the insertion of the new photoconductor 4 is completed, if the tension release lever 31 is rotated counterclockwise in the opposite direction to that described above, the tension plate 52 will be guided to the left by the shaft 54 as the connecting plate 58 is rotated. and moves to the state shown in Fig. 13, and the drum 1
An endless photoreceptor 4 inserted between 6 and 17
Appropriate tension is applied to bring the photoreceptor 4 into close contact with each drum. Next, with the tension release lever 31 forgetting to apply tension to the photoreceptor 4, the upper frame unit 21 is pushed down and combined with the lower frame unit 23 , thereby automatically releasing the tension release lever 3.
1 will be explained. As shown in FIG. 15, the lower frame unit 23 is provided with a projection member 60 at a position facing the tension release lever 31. Therefore, if the upper frame unit 21 is pushed down before applying tension to the photoreceptor 4, the protruding member 60 provided on the lower frame unit 23 will prevent the upper frame unit 21 from moving during the closing process. Therefore, the tip of the projection member 60 comes into contact with the right end of the tension release lever 31, and the tension release lever 31 rotates in the direction of the arrow as shown in FIG. 16, and the small diameter drum 17 moves from the C position to the D position. Then, remove the upper frame unit 21.
Tension is automatically applied to the photoreceptor 4 in response to the closing operation. Here, the height of the protrusion member 60 is determined so that the tip of the protrusion member 60 comes into contact with the right end of the tension release lever 31 immediately before the upper frame unit 21 is completely closed.
Therefore, as mentioned above, I forgot to close the drum unit protective cover 26, and furthermore, the tension release lever 31
If the upper frame unit 21 is pushed down while forgetting to apply tension to the photoreceptor, the drum unit protective cover 26 is closed first, and then the tension release lever 31 is rotated by the projection member 60. It is composed of According to this specific example, one end (rear side) of the drum unit in the direction of the rotational axis is supported by the main body of the apparatus as a fixed end, and the other end (front side) is either a free end or a fixed end depending on whether the drum unit protective cover 26 is opened or closed. It is configured so that. A specific example of the method for supporting the drum unit 24 will be described below. As shown in FIG. 17, the drum unit 24 has a large diameter drum 16 and a small diameter drum attached to a drum support body consisting of a drum unit support frame 61, a drum unit front cover 62, and a top plate 63 that connects and fixes the two at regular intervals. 17 is rotatably supported, and on the rear side of the drum unit 24 , as shown in FIG. 18, the shaft 51 for supporting the small diameter drum 17 is movable in the lateral direction.
The rear tension plate 65 is inserted through a long hole 64 formed in the drum unit support frame 61.
It is rotatably attached to and configured to slide using the elongated hole 64 as a guide. An L-shaped deformed elongated hole 66 is formed in the rear tension plate 65, and the other end of the shaft 54 passing through the drum unit support frame 61 is inserted into this elongated hole 66. Further, a spring (not shown) is installed between the rear tension plate 65 and the drum unit support frame 61 of the drum unit 24 to apply tension from the small diameter drum 17. Further, one end of a connecting plate 67 is fixed to the tip of the shaft 54 passing through the deformed elongated hole 66 of the rear tension plate 65, and this connecting plate 6
A guide pin 68 passing through an L-shaped hole 66 of the rear tension plate 61 is fixed to the other end of the tension plate 7 . One end of the shaft 69 for supporting the large diameter drum 16 is connected to a bearing 7 provided on the drum unit support frame 61.
0, and the other end of the shaft 69 is supported by the drum unit front cover 6 as shown in FIG.
2 is rotatably supported. Each member related to the rear tension plate 65 is located outside the drum unit support frame 61, and an opening 72 is formed in the rear frame 71 of the upper frame unit 21 to correspond to this protrusion. ing. The bearing 70 that pivotally supports the shaft 69 for supporting the large diameter drum 16 is fixed to the drum unit support frame 61 as described above.
0 is the upper frame unit 2 as shown in FIG.
1, and the shaft 69 is supported by the rear frame 71. In this state, the drum unit 24 is cantilever-supported by the rear frame 71 via the shaft 69, but since support is unstable with only this shaft 69, the drum unit support frame 61 is supported by the rear frame 71. The drum unit 24 is fixed by screwing in multiple places with screws 73, and the entire drum unit 24 is attached to the rear frame 71 of the upper frame unit 21 on the rear side.
It will be supported on a cantilever. On the other hand, the drum unit protective cover 26 attached to the upper frame unit 21 so as to be openable and closable is provided with bearings 74 and 75 corresponding to the shafts 69 and 54 for supporting the large diameter drum 16, respectively. When the protective cover 26 is closed, the shaft 69 and shaft 54 for supporting the large diameter drum 16 are
are fitted into bearings 74 and 75 provided on the drum unit protective cover 26, respectively. Therefore, during the copying operation, that is, when the drum unit protective cover 26 is closed, the drum unit 2
4, the upper frame unit 21 securely supports the upper frame unit 21 on both sides. Further, when the drum unit protection cover 26 is open, the rear side of the drum unit 24 is cantilevered by the upper frame unit 21 , and the front side becomes a free end, allowing smooth replacement of the photoreceptor 4, etc. Note that the bearing portions 74, 75 and the shafts 69, 54 are tapered as shown in FIG. 19 so that they can be easily fitted together. According to the above embodiment, the means for setting the endless photoreceptor inserted into the drum unit at a predetermined insertion position is a pre-exposure device for the photoreceptor, which is provided in the main body of the apparatus so as to be openable and closable so as to be located in front of the drum unit. Although the photoreceptor positioning member provided on the drum unit protective cover for prevention is configured, the present invention is not limited to this. Needless to say, any structure may be used as long as the photoreceptor is set at a predetermined insertion position by rotating, opening and closing, or advancing and retracting the attached support member of the photoreceptor positioning member to a predetermined position. <Effects of the Invention> According to the electrophotographic copying apparatus of the present invention, by closing the photoreceptor positioning member during an operation of replacing an endless photoreceptor, the photoreceptor can be reliably inserted into a specified position. In other words, even if you try to close the positioning member with tension applied after the photoconductor is inserted, the closing movement will be restricted, so even if the photoconductor is inserted halfway, the photoconductor may be damaged. By releasing the tension state, the positioning member can be closed, and at this time, the photoreceptor can be inserted reliably. In addition, due to poor insertion,
It is possible to prevent process control signal generation failures, copy mistakes, etc.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the internal structure of an embodiment of an electrophotographic copying apparatus embodying the present invention, FIG. 2 is a sectional view depicting a specific example of an endless photoreceptor, and FIG. FIG. 4 is a plan view showing the operation position of the tension release lever, FIG. 5 is a cross-sectional view of FIG. 4, and FIG. 6 is a drum A diagram showing the positioning operation of the photoconductor by the unit protective cover, FIG. 7 is a diagram showing the mechanism for inhibiting the closing of the drum unit protective cover, and FIGS. 11 is a diagram showing the locking mechanism of the drum unit protective cover. FIG. 12 is a perspective view showing a specific example of the attachment mechanism for the endless photoreceptor. Figures 13 and 14 are side views for explaining the operation of the photoreceptor mounting mechanism, and Figures 15 and 16 are for explaining the movement of the tension release lever in conjunction with the closing operation of the upper frame unit of the main body of the apparatus, respectively. , FIG. 17 is a perspective view showing a specific example of the photosensitive drum unit, FIG. 18 is a side view showing the mounting mechanism of the drum unit, and FIG. 19 is an example of the tapered shaft and bearing part. FIG. 4...Photoreceptor, 16...Large diameter drum, 17...
Small diameter drum, 21 ... Upper frame unit, 23
... lower frame unit, 24 ... drum unit, 26 ... drum unit protective cover, 31 ...
...Tension release lever, 33...Lock release lever,
34...Blocking member, 35...Photoconductor positioning member, 41...Press member, 60...Protrusion member, 6
9, 74, 75...Bearing section.

Claims (1)

[Scope of Claims] 1. In an electrophotographic copying apparatus using an endless sheet-like photoreceptor, at least two drive rollers are provided to support the endless sheet-like photoreceptor so as to be movable along a predetermined path. a drum unit comprising two rollers and having means for applying tension between the rollers and supporting the endless photoreceptor in a tensioned state; and a drum unit capable of releasing the tensioned state of the endless photoreceptor. an insertion section for inserting and removing the endless photoreceptor in a state parallel to the rotational axis of the drum unit; an opening/closing cover which cannot be opened/closed when the tension is not released by the releasing means and becomes openable/closable when the tension is released by the releasing means; An electrophotographic copying apparatus comprising: a photoconductor positioning member provided on the opening/closing cover for pushing the body into a prescribed position.