JP2003021941A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a recording paper is guided smoothly from a carrying belt to the following processing unit even in the case the trailing end of the carrying belt is moved in up-and-down directions. SOLUTION: A movable guide plate 301 is freely rotatably journaled by a fulcrum 302 on a fixing unit 217 side, and the leading end part 301a of the plate 301 is placed on the receiving member 303 of a transfer/carrying belt mechanism 213. Then, the leading end part 301a of the movable guide plate 301 is moved together with the receiving part 303 in the up-and-down directions in accordance with the vertical movement of the trailing end part of the transfer/carrying belt 216. A level difference between the leading end of the recording paper P and the movable guide plate 301 is kept nearly constant, irrespective of the height of the trailing end part of the transfer/carrying belt 216. This is because the position of the leading end part 301a of the movable guide plate 301 with reference to the trailing end part of the transfer/carrying belt 216 is always kept at a fixed level, and the movable guide plate 301 is constituted of a single body never bending halfway.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for transferring an image onto recording paper by an electrophotographic method.

[0002]

2. Description of the Related Art As a conventional image forming apparatus of this type,
For example, there is one as shown in FIG. Here, while the recording paper P is being conveyed by the transfer conveyance belt 601, the toner image formed on the photoconductor drum 602 is transferred to the recording paper P, and the recording paper P is transferred from the transfer conveyance belt 601 to the fixing unit 603. ing. The fixing unit 603 is
A fixing roller 604 and a pressure roller 605 are provided, and the recording paper P is pressed and heated between the rollers 604 and 605 to fix the toner image on the recording paper P.

A transfer / conveying belt 601 and a fixing unit 60
Between the three, the movable guide plate 606 and the fixed guide plate 607
Is provided, and the recording sheet P is guided by these guide plates 606 and 607. The movable guide plate 606 is rotatably supported by a fulcrum 608 on the transfer / conveying belt 601 side, and the tip thereof is received by a fixed guide plate 607.

In this image forming apparatus, the transfer / conveying belt 601 may be inclined as shown in FIG. At this time, although the rear end of the transfer / transport belt 601 is lowered, the movable guide plate 606 is rotated upward, and the connection between the guide plates 606 and 607 is maintained.

[0005]

By the way, in the above-mentioned conventional image forming apparatus, when the fixing unit 603 is pulled out upward and removed, the movable guide plate 606 is prevented from catching the tip of the movable guide plate 606. 606 was shortened. Since the movable guide plate 606 is shortened, the fixed guide plate 607 connected to the movable guide plate 606 is provided on the fixing unit 603 side. Further, in order to reduce the size of the image forming apparatus, the transfer / conveyance belt 6
01 and the fixing unit 603 are narrowed, the movable guide plate 606 and the fixed guide plate 607 accordingly.
Was also shortened. Therefore, in the state of FIG. 6 and the state of FIG. 7, the change in the angle of the movable guide plate 606 is large, and in the state of FIG. 6, the step between the front end of the recording paper P and the movable guide plate 606 is large.

Further, the recording paper P is transferred and conveyed on a transfer belt 601.
Since the recording paper P is electrostatically attracted to the recording paper P, the recording paper P is charged.
Therefore, when the leading end of the recording paper P reaches the movable guide plate 606, the leading end is electrostatically attracted to the movable guide plate 606 and hangs down. In addition, as shown in FIG.
If there is a large step between the front end of the recording sheet P and the movable guide plate 606, the front end of the recording sheet P curls, and the movable guide plate 606
The slip of the leading edge of the recording paper P on the upper side becomes worse, and the recording paper P
There is a difference in transport speed between the tip of the sheet and other portions. Due to this, when the recording paper P is pressed by the rollers 604 and 605 of the fixing unit 603, the recording paper P
There were wrinkles and the like.

Therefore, the present invention has been made in view of the above-mentioned conventional problems. Even when the rear end of the conveyor belt moves up and down, the recording paper is smoothly transferred from the conveyor belt to the next processing unit. An object is to provide an image forming apparatus capable of guiding.

[0008]

In order to solve the above-mentioned problems, the present invention relates to a conveyor belt for conveying recording paper, a processing unit for receiving the recording paper from the conveyor belt and processing it, and a recording paper from the conveyor belt. With a guide plate that guides to the processing unit, supports the conveyor belt in a tiltable manner,
In an image forming apparatus in which the rear end of the conveyor belt moves up and down with respect to the processing unit when the conveyor belt is tilted, the guide plate is rotatably supported on the processing unit side and receives the tip of the guide plate. The receiving member to be placed is provided on the conveyor belt side.

According to the present invention having such a configuration, the guide plate is rotatably supported on the processing unit side, and the receiving member for receiving and mounting the tip of the guide plate is provided on the conveyor belt side. Therefore, when the rear end of the conveyor belt moves up and down, the tip of the guide plate moves up and down together with the receiving member on the conveyor belt side, and the guide plate rotates. At this time, the position of the front end of the guide plate with respect to the rear end of the conveyor belt is always kept constant by the receiving member. Moreover, since this guide plate is a single unit having a length from the processing unit to the conveyor belt, the step between the leading edge of the recording paper and the guide plate does not change significantly, and the leading edge of the recording paper is guided from the conveyor belt to the guide plate. You can always lead to

Further, in the present invention, the processing unit includes a pair of rollers, and the recording paper is passed between the rollers.

As such a processing unit, there is a fixing unit having a fixing roller and a pressure roller. In this fixing unit, the recording paper is received from the conveyor belt through the guide plate, and the recording paper is pressed and heated by each roller. Therefore, if the recording paper is not conveyed properly, wrinkles occur in the recording paper. However, as described above, even if the trailing edge of the conveyor belt moves up and down, the leading edge of the recording paper is always guided from the conveyor belt to the guide plate in the same state. Does not deteriorate, and wrinkles do not occur on the recording paper.

Further, in the present invention, a limiting member for limiting the turning range of the guide plate is provided on the processing unit side.

Here, a limiting member for limiting the turning range of the guide plate is provided so that the guide plate does not freely turn when the processing unit is removed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side view showing the schematic mechanism of the color image forming apparatus of this embodiment. The color image forming apparatus according to the present exemplary embodiment performs so-called copying by reading an image on a document and recording the same image on a recording sheet. In this color image forming apparatus, a document table 111 is provided above the apparatus main body 1. Further, the document table 111
An operation panel to be described later is provided nearby. An image reading unit 110 and an image forming unit 210 are provided inside the apparatus body 1. On the document table 111, a double-sided automatic document feeder (RADF; R) supported so as to be openable and closable with respect to the document table 111.
An ecirculating Automatic Document Feeder) 112 is provided.

The double-sided automatic document feeder 112 includes a document table 1
The document is conveyed to a predetermined position 11 and the document is read by the image reading unit 1.
10, the image reading unit 110 finishes reading an image of one side of the document, the front and back of the document are reversed, and the document is conveyed again to a predetermined position of the document table 111, and the image reading unit The image reading of the other surface of the document by 110 is possible. Then, the double-sided automatic document feeder 1
When the image reading on both sides of the document is completed, the document 12 discharges this document and carries and reverses the next document.
Such document feeding and reversing operations are controlled in relation to the operation of the entire color image forming apparatus. Of course, it is also possible to discharge the original by only reading the image on one side of the original and without reading the other side.

The image reading section 110 reads an image of a document conveyed onto the document table 111 by the double-sided automatic document feeder 112. The image reading unit 110 includes a document table 11
It is provided with first and second document scanning members 113 and 114 that reciprocate in parallel along the lower surface of 1, a lens 115, and a CCD line sensor 116 that is a photoelectric conversion element.

The first original scanning member 113 reciprocates in parallel with the lower surface of the original table 111 at a predetermined scanning speed while maintaining a constant distance, and an exposure lamp for exposing the surface of the original and an original It has the 1st mirror which deflects the reflected light of a to a predetermined direction. In addition, the second document scanning body 11
Reference numeral 4 denotes a unit that reciprocates in parallel with the first document scanning body 113 while maintaining a constant speed relationship, receives reflected light from the document via the first mirror of the first document scanning body 113, and reflects the reflected light. Is further provided with second and third mirrors for deflecting the light in a predetermined direction.

The optical lens 115 is used for the second original scanning member 11
The reflected light of the document deflected by the third and third mirrors 3 is received, the reflected light is condensed, and an optical image is projected on the CCD line sensor 116.

The CCD line sensor 116 sequentially photoelectrically converts the light image, reads a monochrome image or a color image by this, and outputs an image signal indicating the image. This CCD
The line sensor 116 has R (red), G (green), and B (blue).
Is a three-line color CCD that outputs line data that has been color-separated into the respective color components as an image signal.

Here, the first and second document scanning members 113,
The scan by 114 is the sub-scan, and the CCD line sensor 1
When the scanning by 16 is the main scanning, the main scanning is repeated a plurality of times during one sub-scanning, whereby the image on the original is read. During this reading, the CCD line sensor 116 repeatedly outputs line data corresponding to each pixel on the main scanning line, and these line data (image signals) are continuously obtained. This image signal is
It is transferred to an image processing unit (not shown) and processed.

On the other hand, below the image forming section 210, recording sheets (recording media) P are separated one by one and the image forming section 21 is separated.
A sheet feeding mechanism 211 for supplying 0 is provided. The recording sheets P are cut sheets, stacked and accommodated in the sheet tray, separated by the sheet feeding mechanism 211 one by one, and supplied to the image forming unit 210. The recording paper P is guided to a pair of registration rollers 212 arranged in front of the image forming section 210, and when a front end of the recording paper P is detected by a sensor (not shown), recording is performed in response to a detection signal of the sensor. The sheet P is temporarily stopped by each registration roller 212, and then the recording sheet P is conveyed to the image forming unit 210 while the conveyance timing is controlled by each registration roller 212. The image forming unit 210 records an image on one surface of the recording paper P. After this, the recording paper P
After being turned upside down, the sheet is guided again to each registration roller 212, an image is recorded on the other surface of the recording sheet P by the image forming unit 210, and the recording sheet P is further ejected. Of course, it is also possible to eject the recording paper P without recording the image on the other surface only by recording the image on the one surface of the recording paper P.

A transfer / transport belt mechanism 213 is arranged below the image forming section 210. The transfer / conveying belt mechanism 213 includes a driving roller 214, a driven roller 215,
Further, a transfer conveyance belt 216 stretched between the rollers 214 and 215 is provided, and the recording paper P is conveyed in the arrow Z direction while electrostatically adsorbing the recording paper P on the transfer conveyance belt 216. During the transportation by the transfer / transport belt mechanism 213, a toner image is transferred and formed on the recording paper P as described later.

The paper suction (brush) charger 228 is arranged immediately after each registration roller 212 and charges the transfer / transport belt 216. As a result, the recording sheet P is conveyed in the image forming section 210 while being surely adsorbed onto the transfer / conveying belt 216.

A static eliminator 229 is provided between the image forming section 210 and the fixing unit 217. This static eliminator 22
An alternating current for applying the recording paper P electrostatically attracted to the transfer / transport belt 216 to the transfer / transport belt 216 is applied to the sheet 9.

The fixing unit 217 includes a fixing roller 217.
a and a pressure roller 217b, receives the recording paper P from the transfer / conveying belt mechanism 213 via the movable guide plate 301, and pressurizes and heats the recording paper P at the nip portion between the rollers 217a and 217b. As a result, the toner image transferred and formed on the recording paper P is fixed on the recording paper P. After this, the recording paper P is transferred to the transport switching gate 2
After passing 18, the sheet is discharged by a discharge roller 219 to a sheet discharge tray 220 attached to the outer wall of the apparatus main body 1.

The switching gate 218 selectively switches a path for discharging the recording paper P after fixing to the paper discharge tray 220 and a path for supplying the recording paper P after fixing again to the image forming section 210. . When the recording paper P is supplied again to the image forming unit 210 by the switching gate 218, the recording paper P is turned upside down via the switchback transport path 221, and then guided to the image forming apparatus 210.

The first image forming station Pa, the second image forming station Pb, the third image forming station Pc, and the third image forming station Pc are provided in the image forming section 210 in the vicinity of the transfer conveying belt 216 from the upstream side of the conveying path of the recording paper P. Four
The image forming stations Pd are arranged in parallel. As described above, the recording paper P on the transfer / transport belt 216 is transported in the arrow Z direction. As a result, the recording paper P is transferred to the first, second, third and fourth image forming stations Pa, Pb, P.
Pass c and Pd in the order listed. The first to fourth image forming stations Pa to Pd have substantially the same configuration and include respective photoconductor drums 222a, 222b, 222c, 222d which are rotationally driven in the arrow F direction.

Chargers 223a, 223b, 223c and 223 for uniformly charging the photoconductor drums 222a to 222d are provided near the photoconductor drums 222a to 222d.
d, laser scanner units 227 that form electrostatic latent images on the photoconductor drums 222a to 222d, respectively.
a, 227b, 227c, 227d, each photosensitive drum 2
Developing devices 224a, 224b, 224c, which develop respective electrostatic latent images on 22a to 222d to form respective toner images.
224d, each transfer discharger 225 that transfers each toner image on each photoconductor drum 222a to 222d to the recording paper P
a, 225b, 225c, 225d, each photosensitive drum 2
Cleaning devices 226a, 226b, 226c, for removing the toners remaining on 22a to 222d,
226d is arranged.

Each laser scanner unit 227a-2
27d is a semiconductor laser element (not shown) that emits a laser beam modulated according to an image signal, a polygon mirror (deflecting device) 240 for deflecting the laser beam from the semiconductor laser element in the main scanning direction, and a polygon mirror. Two
The laser beam deflected by 40 is applied to each photosensitive drum 2
Fθ lens 2 that focuses and images on 22a to 222d
41, and each mirror 242, 243, etc.

The laser beam scanner 227a inputs an image signal corresponding to the black component image of the color image, modulates the laser beam according to this image signal, and outputs the laser beam corresponding to the black component image to the photosensitive drum 222a. Irradiate. The laser beam scanner 227b inputs an image signal corresponding to the cyan component image of the color image, modulates the laser beam according to this image signal, and irradiates the photoconductor drum 222b with the laser beam corresponding to the cyan component image. To do. The laser beam scanner 227c inputs an image signal corresponding to the magenta color component image of the color image, modulates the laser beam in accordance with this image signal, and outputs the laser beam corresponding to the magenta color component image to the photoconductor drum 222.
Irradiate c. The laser beam scanner 227d inputs an image signal corresponding to the yellow color component image of the color image, modulates the laser beam according to this image signal, and irradiates the photoconductor drum 222d with the laser beam corresponding to the yellow color component image. To do. By exposing the photoconductor drums by the laser beam in this manner, the electrostatic latent image of the black component image, the electrostatic latent image of the cyan component image, and the electrostatic latent image of the magenta component image are formed on the photoconductor drums 222a to 222d. An electrostatic latent image of the latent image and the yellow color component image is formed.

The developing device 224a contains black toner, and this black toner is applied to the photosensitive drum 222a.
It adheres to the electrostatic latent image of the black component image above, thereby developing a black toner image. The developing device 224b contains cyan toner, and this cyan toner adheres to the electrostatic latent image of the cyan component image on the photoconductor drum 222b, whereby the cyan toner image is developed. It The developing device 224c contains magenta toner, and the magenta toner adheres to the electrostatic latent image of the magenta component image, whereby the magenta toner image is developed. The developing device 224d contains a yellow toner, and the yellow toner adheres to the electrostatic latent image of the yellow component image, whereby the yellow toner image is developed.

As the photosensitive drums 222a to 222d rotate, the photosensitive drums 222a to 222d are sequentially pressed against the recording paper P on the transfer / conveying belt 216, so that the toner images on the photosensitive drums 222a to 222d are formed. The recording sheets P are sequentially superposed and transferred. After that, the recording sheet P is conveyed to the discharging discharging device 229, and the discharging discharging device 229 removes static electricity, and the transfer conveying belt 2 is discharged.
After being peeled from 16, it is guided to the fixing unit 217. The fixing unit 217 fixes the toner image transferred and formed on the recording paper P. The recording paper P is discharged to the paper discharge tray 220 by the discharge roller 219 via the transport switching gate 218, or the switching gate 21.
8 is turned upside down via the switchback conveyance path 221 and then guided again to the image forming apparatus 210.

It should be noted that, in this case, each of the photoconductor drums 222 is controlled by each of the laser scanner units 227a to 227d.
Although an image is written to a to 222d, a writing optical system (LED head) including a light emitting diode array and an imaging lens array may be used instead of the laser scanner units 227a to 227d. This LED head is smaller in size than a laser scanner unit, and has no moving parts and produces no operating noise. Therefore, in an image forming apparatus such as a tandem type digital color copying machine which requires a plurality of writing units, L
ED heads are preferred.

By the way, in the color image forming apparatus of this embodiment, when a color image is recorded on the recording paper P, the transfer / conveying belt 216 is maintained substantially horizontal as shown in FIG. 222a to 222d are kept in contact with the transfer / transport belt 216, and
While conveying the recording paper P by 6, the photoconductor drums 22
2a to 222d, the black component image, the cyan color component image, the magenta color component image, and the yellow color component image are sequentially superimposed and transferred onto the recording paper P, and thereafter, the recording paper P is moved to a movable guide plate as shown in FIG. It guides to the fixing unit 217 via 301.

When recording a black and white image on the recording paper P, the transfer / conveying belt 216 is set to the fulcrum 2 as shown in FIG.
By rotating the transfer conveyor belt 216 around 31, the photosensitive drum 222a is brought into contact with the transfer conveyor belt 216, and the other photosensitive drums 222 are rotated.
b to 222d are separated from the transfer / transport belt 216.
Then, in this state, only the black component image is transferred onto the recording paper P by the photosensitive drum 222a, and thereafter, the recording paper P is guided to the fixing unit 217 via the movable guide plate 301 as shown in FIG. In this way, if the other unnecessary photoconductor drums 222b to 222d are separated from the transfer / conveying belt 216, these photoconductor drums 222b to 222d
It is not necessary to waste 222d.

Here, as shown in FIG.
In a state where 16 is maintained substantially horizontal, the rear end of the transfer / conveying belt 216 is maintained at a predetermined height as shown in FIG.
Further, when the transfer / transport belt 216 is inclined as shown in FIG. 3, the rear end of the transfer / transport belt 216 is lowered as shown in FIG.

As shown in FIGS. 4 and 5, the movable guide plate 30 is provided.
1 is rotatably supported by a fulcrum 302 on the side of the fixing unit 217, and its front end portion 301a is attached to the transfer / conveying belt mechanism 2.
It is placed on the receiving member 303 fixed to 13. Therefore, as the rear end of the transfer / transport belt 216 moves up and down,
The front end portion 301a of the movable guide plate 301 moves up and down together with the receiving member 303 on the transfer / transport belt 216 side. As is clear from the comparison between FIG. 4 and FIG. 5, the step between the front end of the recording paper P and the movable guide plate 301 is kept substantially constant regardless of the height of the rear end of the transfer / transport belt 216. This is the movable guide plate 30 with respect to the rear end of the transfer / transport belt 216.
This is because the position of the front end portion 301a of No. 1 is always kept constant by the receiving member 303, and the movable guide plate 301 is a single piece that does not bend in the middle.

If the step between the front end of the recording paper P and the movable guide plate 301 is kept substantially constant in this way, the front end of the recording paper P is always guided from the transfer / conveying belt 216 to the movable guide plate 301 in the same state. And the leading edge of the recording paper P always slides on the movable guide plate 301 in the same state,
There is no difference in the conveying speed between the tip of the and other parts. Therefore, regardless of the height of the rear end portion of the transfer / transport belt 216, the recording paper P can be always guided to the nip portion between the rollers 217a and 217b of the fixing unit 217 in the same state, and the recording paper P is wrinkled. It doesn't occur.

When inspecting, servicing or replacing the fixing unit 217, the fixing unit 217 is pulled out upward. At this time, the movable guide plate 301 rotates downward due to its own weight, but stops by hitting the limiting member 304 fixed to the fixing unit 217. As a result, even if the fixing unit 217 is pulled out, the movable guide plate 301 does not have to move freely. Also, the fixing unit 2
When the fixing unit 217 is mounted, if the fixing unit 217 is lowered as it is, the front end portion 301a of the movable guide plate 301
Is placed on the receiving member 303, and the movable guide plate 301 is set. Therefore, the fixing unit 217 can be easily attached and detached.

The present invention is not limited to the above embodiment and can be variously modified. For example,
The shapes and mounting positions of the receiving member 303 and the limiting member 304 may be changed appropriately. Further, the shape of the movable guide plate 301 may be changed.

[0042]

As described above, according to the present invention, the guide plate is rotatably supported on the processing unit side, and the receiving member for receiving and mounting the tip of the guide plate is provided on the conveyor belt side. . Therefore, when the rear end of the conveyor belt moves up and down,
The tip of the guide plate moves up and down together with the receiving member on the side of the conveyor belt, and the guide plate rotates. At this time, the position of the front end of the guide plate with respect to the rear end of the conveyor belt is always kept constant by the receiving member. Moreover, since this guide plate is a single unit having a length from the processing unit to the conveyor belt, the step between the leading edge of the recording paper and the guide plate does not change significantly, and the leading edge of the recording paper is guided from the conveyor belt to the guide plate. You can always lead to

Also according to the invention, the processing unit comprises:
For example, there is a fixing unit including a fixing roller and a pressure roller. In this fixing unit, the recording paper is received from the conveyor belt through the guide plate, and the recording paper is pressed and heated by each roller. Therefore, if the recording paper is not conveyed properly, wrinkles occur in the recording paper. However, as described above, even if the trailing edge of the conveyor belt moves up and down, the leading edge of the recording paper is always guided from the conveyor belt to the guide plate in the same state. Does not deteriorate, and wrinkles do not occur on the recording paper.

Further, according to the present invention, the limiting member is provided for limiting the turning range of the guide plate so that the guide plate does not freely turn when the processing unit is removed.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic mechanism of a color image forming apparatus of this embodiment.

FIG. 2 is a side view showing a state of a transfer / conveyance belt when a color image is recorded in the apparatus of FIG.

3 is a side view showing a state of a transfer / conveying belt when recording a monochrome image in the apparatus of FIG. 1. FIG.

4 is a side view showing a state of a rear end portion of a transfer / conveyance belt and a movable guide plate when a color image is recorded in the apparatus of FIG.

5 is a side view showing a state of a rear end portion of a transfer / conveying belt and a movable guide plate when recording a monochrome image in the apparatus of FIG.

FIG. 6 is a side view showing a state of a rear end portion of a transfer conveyance belt and a movable guide plate which are kept substantially horizontal in a conventional apparatus.

7 is a side view showing a state of a movable guide plate and a rear end portion of an inclined transfer / conveying belt in the apparatus of FIG.

[Explanation of symbols]

1 device body 110 image reading unit 112 Double-sided automatic document feeder 116 CCD line sensor 210 Image forming unit 211 Paper feed mechanism 220 output tray 222a-222d photoconductor drum P recording paper Pa First image forming station Pb second image forming station Pc Third image forming station Pd 4th image forming station 301 Movable guide plate 302 Support point 303 Receiving member 304 restriction member

Continued front page    (72) Inventor Yu Tsuji             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F term (reference) 2H033 AA14 BA02 BA09 BB00                 2H072 CA01 CA05 CB08 JA04                 3F049 AA01 BA01 DB02 DB04 LA02                       LA06 LB03                 3F101 FA01 FB07 FE02 LA02 LA07                       LB03

Claims (3)

[Claims] 1. A conveyor belt for conveying recording paper, a processing unit for receiving recording paper from the conveyor belt and processing it, and a guide plate for guiding the recording paper from the conveyor belt to the processing unit. Support possible,
In an image forming apparatus in which the rear end of the conveyor belt moves up and down with respect to the processing unit when the conveyor belt is tilted, the guide plate is rotatably supported on the processing unit side and receives the tip of the guide plate. An image forming apparatus characterized in that a receiving member to be placed is provided on a side of a conveyor belt. 2. The processing unit comprises a pair of rollers,
2. A recording sheet is passed between each roller.
The image forming apparatus according to item 1. 3. The image forming apparatus according to claim 1, wherein a limiting member that limits the rotation range of the guide plate is provided on the processing unit side.