JP3658444B2 - Color image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color image forming apparatus such as a color copying machine, a color printer, and a color facsimile having an intermediate transfer member.
[0002]
[Prior art]
In a color image forming apparatus having an intermediate transfer member, the intermediate transfer member is handled as a replaceable disposable part for reasons such as mechanical fatigue and surface deterioration. The challenge is how to facilitate maintenance such as jam handling. As a conventional technique for solving this problem, as described in JP-A-4-318875, a recording belt is configured in a triangular shape, a plurality of developing units are provided in the upper part, and a laser beam generator and a feeding unit are provided in the lower part. “Color image electronics” has a configuration in which a paper cassette is arranged, a transfer drum is provided between the paper cassettes, a paper feeding unit is arranged on the opposite side of the transfer drum from the recording belt, and the paper moves in a straight line from the bottom to the top. A photographic apparatus has been proposed.
[0003]
In addition, a process cartridge including a plurality of development units and at least an image carrier is arranged in the apparatus main body, a paper feeding unit is arranged on the lower side, and a paper ejection unit is arranged on the upper side, and the paper ejection unit is discharged from the paper feeding unit. In a color image forming apparatus provided with a transfer paper transport path extending in a direction leading to a paper section, the front body can open the transfer paper transport path centering on the lower side with respect to the stationary housing. A plurality of developing units are installed in the non-moving portion housing, and a holding rotation member that enables the process cartridge to turn in the same direction as the opening direction of the front housing is provided in the non-moving portion housing. A color image forming apparatus provided in the present invention has been proposed by the applicant of the present invention.
[0004]
[Problems to be solved by the invention]
By the way, as each unit arrangement of the color image forming apparatus using the intermediate transfer member, in order to shorten the transfer path length of the transfer paper, as shown in the conventional example, a paper feeding unit is provided at the lower part of the apparatus main body. In addition, a fixing / paper discharge unit is disposed at the top, and the transfer paper transport path is formed substantially vertically. Here, since the intermediate transfer body performs color superimposition of the image before transfer onto the transfer paper on the surface thereof, if the size of the transfer paper that can be transferred increases, the intermediate transfer body itself also increases accordingly. For example, an intermediate transfer body corresponding to a large size transfer paper such as A3 size (297 × 429 mm) or DLT size (279 × 432 mm) is for A4 size (210 × 297 mm) or LT size (216 × 279 mm). The size is twice that of the intermediate transfer member.
[0005]
Further, as described above, in the apparatus in which the transfer paper transport path is formed substantially vertically, as shown in the conventional example, the front casing is rotated with respect to the stationary casing of the apparatus main body. The jamming process is performed by opening the transfer paper conveyance path. In this case, a pair of transport rollers (for example, registration rollers) arranged in front of the transfer position also has one roller on the front housing side and the other roller on the non-moving portion housing side by opening the transport path. (Process cartridge side) are arranged so as to be separated from each other.
[0006]
That is, in a normal monochrome image forming apparatus, the pair of conveying rollers are often arranged on the stationary part housing side, but in a color image forming apparatus using an intermediate transfer member, the process is performed. Since the cartridge includes the intermediate transfer member, the cartridge is enlarged as described above, and the exterior surface thereof is also used as one guide surface of the transfer paper transport path. When arranged on the housing side, when the process cartridge is replaced, this transport roller interferes with the replacement operation, and the operability during the maintenance deteriorates. In order to solve this problem, the provision of the pair of transport rollers integrally with the process cartridge means that the transport rollers, which are inherently part of the apparatus life, are discarded every time the process cartridge is replaced. This is uneconomical and inefficient.
[0007]
Therefore, in a color image forming apparatus using this type of intermediate transfer member, as described above, only one of the pair of transport rollers (usually a driven roller) is provided on the process cartridge side, and as described above. To alleviate various problems.
[0008]
However, in the conventional color image forming apparatus, when a small-size transfer sheet is jammed on the intermediate transfer body, if the apparatus is compatible with A4 size or LT size during the jam processing, The jam paper on the exterior surface of the process cartridge, which is one transfer paper conveyance guide surface, is prevented from falling by the unopened guide plate below, and is held in that position. As described above, in an A3 size or DLT size compatible device, the intermediate transfer body itself is large and the opening portion itself is also large. Therefore, the jammed paper falls due to the opening of the front housing, and is out of the user's viewing position. There is. Further, in this case, there is a high possibility that the unfixed image on the transferred transfer paper is contaminated with the guide plate of the transfer paper transport path.
[0009]
[Means for Solving the Problems]
In the present invention, a transfer roller for transferring the transfer paper arranged on the process cartridge side is provided on the front housing side, and the transfer paper jammed on the intermediate transfer member is moved to the front housing side during the jam processing. To do. In this way, by providing the process cartridge-side transport roller on the front housing side, the process cartridge-side transport roller that causes deterioration in operability and economic effect at the time of process cartridge replacement is eliminated, and jamming occurs. The transfer paper is held on the front housing side without dropping.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the color image forming apparatus according to the present invention, a pair of transfer rollers for transferring the transfer paper disposed on the front side of the image transfer position of the process cartridge is provided on both sides of the front casing.
[0011]
Further, as described above, even when the transfer paper jammed on the intermediate transfer member during the jam processing is moved to the front housing side, when the user pulls the jammed paper in a direction opposite to the conveyance direction, the jammed paper is transferred. Since the transport roller is contaminated by the unfixed image on the paper, the jammed paper is rotated only in the transfer paper transport direction on the drive roller side of the pair of transport rollers so as not to be pulled in the direction opposite to the transport direction. It is preferable to provide a unidirectional rotation restricting member that allows
[0012]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of an image forming apparatus in which the car embodying the present invention. In FIG. 1, a photosensitive belt 1 that is a belt-like image carrier is provided between rotating rollers 2 and 3 and is rotated in the clockwise direction when the rotating roller 3 is driven. Around the photosensitive belt 1, there is a rotary charger comprising a charging charger 4 as a charging means, a laser writing unit 5 as an image exposure means, and three developing means individually containing yellow, magenta and cyan color developers. Known color image forming means using an electrophotographic method such as a color developing unit 6 and a black developing unit 7 containing a black developer are provided.
[0013]
The color developing unit 6 and the black developing unit 7 are each provided with a developing roller that comes close to or in contact with the photosensitive belt 1 at a predetermined position, and the photosensitive belt 1 formed by the laser writing unit 5. The above electrostatic latent image is visualized by a non-contact development method or a contact development method. As a result, the first color developed image formed on the photosensitive belt 1 is transferred to the intermediate transfer belt 10 as an intermediate transfer member which contacts the photosensitive belt 1 at the portion of the rotating roller 3. The image is transferred by a bias brush 13 provided in the belt 10. The intermediate transfer belt 10 is installed between the rotation rollers 11 and 12, and is rotated synchronously in the counterclockwise direction at the same rotation speed as that of the photosensitive belt 1 by driving the rotation roller 11. . In this way, the same process as described above is repeated a plurality of times (four times if there are four colors) according to the number of colors of the image to be formed, so that the visible images of the respective colors are color-shifted on the intermediate transfer belt 10. They are superimposed so that there is no (primary transfer).
[0014]
Here, the photosensitive belt 1, the intermediate transfer belt 10, the respective rotating rollers 2, 3, 11, and 12, the cleaning / waste toner storage box 15 for the photosensitive belt 1, and the cleaning unit for the intermediate transfer belt 10. 16 is integrally configured as one process cartridge 25.
[0015]
On the other hand, a paper feed cassette 17 and a paper feed roller 18 on which transfer paper is set are disposed below the main body frame 9 which is a stationary housing of the main body of the color image forming apparatus. The transfer paper P fed from the paper feed cassette 17 by the paper feed roller 18 is a front case that is disposed so as to be openable and closable with respect to the main body frame 9 with a support shaft 9a at the lower part of the main body frame 9 as a rotation center. A gap between the guide surface of the conveyance guide plate 8a of the front frame 8 and the exterior surface 25a of the process cartridge 25 as a conveyance path, and a pair of intermediate conveyance rollers 19a and 19b disposed across the conveyance path, The process cartridge 25 is transported until it reaches the nip portion of the registration roller 20 as a pair of transport rollers for transporting the transfer paper disposed on the front side of the image transfer position (secondary transfer portion) of the process cartridge 25 and waits once. Is done.
[0016]
Next, the waiting transfer sheet P is timed with a color toner image (unfixed image) formed on the intermediate transfer belt 10, and the intermediate transfer belt 10 and the transfer roller 14 that are secondary transfer portions. Is fed again by the rotation of the registration roller 20 toward the contact portion. Here, the transfer roller 14 is separated from the intermediate transfer belt 10 during the color superimposing step of each color toner image on the intermediate transfer belt 10, and the intermediate transfer after the color superposition of each color toner image is finished. Only when the color toner image on the belt 10 is transferred onto the transfer paper P (secondary transfer), it is brought into contact with the intermediate transfer belt 10.
[0017]
After the transfer paper P re-fed by the rotation of the registration roller 20 is biased at the contact portion between the intermediate transfer belt 10 and the transfer roller 14 and an unfixed image is transferred from the intermediate transfer belt 10, The unfixed image is transported to a fixing device 50 disposed downstream of the secondary transfer portion to fix an unfixed image, and is discharged as a color copy by a paper discharge roller 51 to a paper discharge portion at the top of the apparatus main body.
[0018]
By the way, the replacement and maintenance of the process cartridge 25 in this type of color image forming apparatus is performed by moving the front frame 8 with respect to the main body frame 9 around the support shaft 9a at the lower part of the main body frame 9, as shown in FIG. By rotating in the clockwise direction and pulling out in the direction of arrow A with the transfer path of the transfer paper P formed by the guide surface of the transport guide plate 8a of the front frame 8 and the exterior surface 25a of the process cartridge 25 open. Done. Also, the transfer paper P jammed in the transport path is processed by opening the front frame 8 with respect to the main body frame 9 as described above.
[0019]
Here, in the conventional color image forming apparatus, with the front frame 8 opened as described above, one of the registration rollers 20 (generally, the driven roller 20b) is, as shown in FIG. As described above, the driven roller 20b obstructs the replacement of the process cartridge 25, or replaces the driven roller 20b, which is a component that has essentially the life of the apparatus, with the replacement of the process cartridge 25. Therefore, it is discarded, which is uneconomical and inefficient. In this conventional color image forming apparatus, as shown in FIG. 4, when the leading edge of the transfer paper P jams between the secondary transfer portion and the entrance of the fixing device 50, the transfer paper P Since the unfixed image T has already been transferred from the intermediate transfer belt 10 to the leading end side, when the front frame 8 is opened and the jammed paper falls in this state, the jammed paper unfixed image T and the process cartridge 25 are removed. As a result, the exterior surface 25a of the process cartridge 25 and the driven roller 20a are contaminated with unfixed toner, and the transfer paper to be conveyed next is contaminated with toner.
[0020]
Therefore, in the color image forming apparatus of the present invention, as shown in FIGS. 2 and 5, the driving roller 20a and the driven roller 20b of the registration roller 20 as well as the transfer roller 14 and the intermediate conveying roller 19a are connected to the side plate 8b of the front frame 8. Are arranged and configured. Therefore, in the color image forming apparatus of the present invention, as shown in FIG. 2, the driving roller 20a and the driven roller 20b of the registration roller 20 are moved to the front frame 8 side with the front frame 8 opened. As in the conventional example, the driven roller 20b does not obstruct the replacement of the process cartridge 25, and the driven roller 20b, which is a component that originally has a lifetime of the apparatus, is not discarded by the replacement of the process cartridge 25. , Its economic efficiency is improved. In the color image forming apparatus of the present invention, when the leading edge of the transfer paper P jams between the secondary transfer portion and the entrance of the fixing device 50, the front frame 8 is opened and moved to the front frame 8 side. Since the jammed paper is held by the pair of registration rollers 20 and the jammed paper does not fall, the unfixed image T of the jammed paper and the exterior surface 25a of the process cartridge 25 rub against each other as in the conventional example. Thus, the exterior surface 25a of the process cartridge 25 and the driven roller 20a are not contaminated with unfixed toner, and the transfer paper to be conveyed next is not contaminated with toner.
[0021]
Here, as shown in FIG. 6, the driving roller 20a of the registration roller 20 in the color image forming apparatus of the present invention is a secondary transfer of the transfer paper P by a bearing 100 incorporating a one-way rotation restricting member (one-way clutch). It is attached to the side plate 8b so as to be rotatable only in the direction (arrow direction in FIG. 6) in which the sheet is conveyed. The driven roller 20b of the registration roller 20 is urged in a direction in which it is pressed against the drive roller 20a by the elastic force of the coil spring 102 via a normal bearing 101, and is rotatably supported by the side plate 8b. .
[0022]
With reference to FIG. 7, a jam handling operation in the color image forming apparatus of the present invention when the leading edge of the transfer paper P jams between the secondary transfer portion and the entrance of the fixing device 50 will be described. In FIG. 7, the jammed paper PA in the conventional color image forming apparatus is left on the exterior surface 25a of the process cartridge 25 on the main body frame 9 side as indicated by the chain line, and the unfixed image T is left on the main body frame 9 side. Therefore, the user cannot view the unfixed image T on the jammed paper PA with the front frame 8 opened. For this reason, in the conventional color image forming apparatus, when this jammed paper PA is processed, the user unintentionally touches the unfixed image T of the jammed paper PA and stains his hand, or this is caused by the user. There is a high possibility that the jammed paper PA is pulled out from the rear end side, and the exterior surface 25a of the process cartridge 25 and the driven roller 20b of the registration roller 20 are contaminated by the unfixed image T.
[0023]
On the other hand, the jammed paper PB in the color image forming apparatus of the present invention is held between the pair of registration rollers 20 and held on the conveyance guide plate 8a on the front frame 8 side, as shown by the solid line in FIG. Since the unfixed image T is exposed on the front frame 8, the user can easily visually check the unfixed image T on the jammed paper PB with the front frame 8 opened. Therefore, in the color image forming apparatus of the present invention, when processing the jammed paper PB, the possibility that the user touches the unfixed image T on the jammed paper PB and gets his hands dirty is extremely low. In the color image forming apparatus of the present invention, as described above, the driving roller 20a of the registration roller 20 can be rotated only in the direction in which the transfer paper P is conveyed to the secondary transfer portion by the bearing 100 incorporating the one-way clutch. In other words, the jammed paper PB cannot be pulled out from the rear end side, and the unfixed image T causes the driving roller 20a and the driven roller 20b of the registration roller 20 to be contaminated. Nor.
[0024]
【The invention's effect】
As described above, according to the present invention, the pair of transfer rollers (registration rollers) for transferring the transfer paper disposed on the front side of the image transfer position of the process cartridge is disposed on the front housing side, thereby being immovable. Since the jammed paper can be moved together with a pair of transport rollers to the front case side that is pivotally opened relative to the main case, the unfixed image on the jammed paper can be used to dispose the exterior surface of the process cartridge and the user's hand. The problem of contamination can be solved, and the problem that one of the transport rollers interferes with the replacement of the process cartridge or is discarded before the original life is reached.
[0025]
In addition, by providing a one-direction rotation restricting member that allows rotation only in the transfer paper conveyance direction on the drive roller side of the pair of conveyance rollers, it becomes impossible to pull out jammed paper from the rear end side during jam processing. This unfixed image of jammed paper can prevent the above-mentioned pair of conveyances from being contaminated.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an embodiment of a color image forming apparatus of the present invention.
FIG. 2 is a schematic cross-sectional view showing a state where a front housing of an embodiment of the color image forming apparatus of the present invention is opened.
FIG. 3 is a cross-sectional view of a transfer paper transport unit for explaining a problem caused by an unfixed image on jammed paper that occurs when the present invention is not applied.
FIG. 4 is an enlarged cross-sectional view of a main part of a transfer paper transport unit for explaining a problem caused by an unfixed image on jammed paper that occurs when the present invention is not applied.
FIG. 5 is a cross-sectional view of the main part of the front housing in one embodiment of the color image forming apparatus of the present invention.
FIG. 6 is an enlarged cross-sectional view of a main part of a front housing in one embodiment of a color image forming apparatus of the present invention.
FIG. 7 is a schematic cross-sectional view for explaining a jam handling operation in an embodiment of a color image forming apparatus of the present invention.
FIG. 8 is an enlarged cross-sectional view of a main part for explaining a jam processing operation in an embodiment of a color image forming apparatus of the present invention.
[Explanation of symbols]
1 Photosensitive Belt 4 Transfer Charger 5 Laser Writing Unit 6 Rotating Color Developer 7 Black Developer 8 Front Frame (Front Case)
9 Body frame (non-moving part housing)
DESCRIPTION OF SYMBOLS 10 Intermediate transfer belt 13 Bias brush 14 Transfer roller 15 Waste toner storage box 16 Cleaning unit 17 Paper feed cassette 18 Paper feed rollers 19a and 19b Intermediate transport roller 20 Registration roller 20a Registration roller drive roller 20b Registration roller driven roller 25 Process cartridge 25a Exterior surface 50 of process cartridge Fixing device 51 Paper discharge roller 100 Bearing P with built-in one-way clutch Transfer paper PA Jam paper PB in conventional apparatus Jam paper in this embodiment

Claims (1)

A paper feed unit is disposed on the lower side of the apparatus main body, and a paper discharge unit is disposed on the upper side, and has a transfer paper conveyance path from the paper supply unit to the paper discharge unit. A front housing that rotates so as to open the transfer paper conveyance path with respect to the non-moving portion housing with the lower portion of the non-moving portion housing as a center of rotation, and an exterior surface is one side of the transfer paper conveyance route In a color image forming apparatus having a process cartridge including an intermediate transfer body set on the stationary part housing side so as to form a guide surface of the above, a pair of registration rollers disposed on the front side of the image transfer position of the process cartridge A color image forming apparatus, characterized in that a unidirectional rotation restricting member that is disposed on a front housing side and that allows rotation only in a transfer sheet conveying direction is provided on a driving roller side of the registration roller pair .

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