JP3969211B2 - Paper transport device, post-processing device, and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus, and more particularly to a sheet conveying apparatus including a curl correcting unit called a decurler that corrects curling of a sheet, and an apparatus such as an image forming apparatus including the sheet conveying apparatus.
[0002]
[Prior art]
There is an image forming apparatus that gives curl to the paper, such as fixing in an electrophotographic image forming apparatus, and there are cases where the paper used has curl, and handling of such curled paper is a problem. In many cases.
[0003]
For example, in a post-processing apparatus that performs binding processing and folding processing on image-formed paper, the curled paper causes jamming, or the paper that has been imaged and formed is not aligned and the paper bundle is aligned. It may take time.
[0004]
For this reason, an image forming apparatus and a post-processing apparatus equipped with a curl correction means (hereinafter also referred to as a decurler) called a decurler have been proposed and put into practical use.
[0005]
[Problems to be solved by the invention]
Since the degree of curling of paper varies depending on the paper quality, thickness, humidity, and the like of the paper, a decurler capable of changing the degree of curl correction in addition to the decurler having a certain degree of curl correction has been proposed. Such a decurler having a variable degree of curl correction is configured to be set by an operator, and in use, the operator checks the degree of curl of the paper and sets the degree of curl correction of the decurler. Become. In this case, in order to set an appropriate degree of curl correction, it is necessary to perform trial baking, and it takes time and labor to set the curl correction condition, and there is a case where appropriate curl correction is not performed. .
[0006]
As described above, in the conventional decurler, not only the time and time are required for setting the degree of curl correction, but also there is a problem that the curl is not properly corrected.
[0007]
Also, many conventional decurlers perform curl correction only in one direction. To correct curl in any direction, it is necessary to install two conventional decurlers with the curl correction directions opposite to each other. There was a problem that the apparatus became large.
[0008]
An object of the present invention is to solve the above-mentioned problems in conventional decurlers.
[0009]
[Means for Solving the Problems]
The object of the present invention is achieved by the following invention.
[0010]
1. Curl detection means for detecting paper curl,
A curl correction means having three rollers and a support means that supports and rotates these rollers, and the direction of curl correction changes by rotation of the support means;
A pair of fixed guides for guiding the paper in the curl correcting means;
A paper conveying apparatus comprising: a control unit that controls the curl correcting unit by rotating the support unit based on the output of the curl detecting unit .
2. The paper conveying apparatus according to claim 1, wherein the curl detection unit includes a movable guide that is displaced following the curl of the paper, and a displacement detection unit that detects a displacement amount of the movable guide.
3. The sheet conveying apparatus according to claim 2, wherein the displacement detection unit includes a variable resistor whose resistance value changes according to the displacement of the movable guide.
4). An image forming apparatus comprising the sheet conveying device according to claim 1.
5. The image forming apparatus according to claim 4, further comprising an image forming unit and a fixing device, wherein the paper transport device transports the paper that has passed through the fixing device.
6). A post-processing apparatus comprising the sheet conveying apparatus according to claim 1.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(1) Image Forming Apparatus FIG. 1 is a view showing an image forming apparatus and a post-processing apparatus according to an embodiment of the present invention.
[0018]
In the figure, 10 is an image forming unit that forms an image on a sheet by electrophotography, 20 is an image reading unit that reads an image of a document and generates image data, 30 is a sheet storage unit that stores sheets, and 40 is This is a post-processing device that performs post-processing such as binding processing, shift processing, folding processing, and punching processing on a sheet on which an image is formed. The image forming unit 10, the image reading unit 20, and the paper storage unit 30 form an image forming apparatus.
[0019]
The image forming unit 10 includes a photoconductor 11, forms a toner image on the photoconductor 11 by charging, exposure, and development, and transfers the toner image formed on the photoconductor 11 to a sheet. A fixing device FX for fixing the transferred unfixed image, a reversing conveyance unit 14 for reversing the sheet on which the image is formed on one side, sheet feeding means 16a, 16b, 16c for feeding the sheet from the sheet storage unit 30, and manual feeding A paper feed tray 17 is provided.
[0020]
The image reading unit 20 receives an image light, a document feeding table 21 on which a document is placed, a platen roller 22 that conveys the document and forms a reading position, a document discharge table 23 on which the read document is placed, and an image light. The image sensor 24 for converting to an image signal, a lamp and a mirror for illuminating the document, a movable scanning unit 25 for scanning the document placed on the document placing table 27, and two mirrors. It has a scanning unit 26 that can move at half the speed.
[0021]
The image reading unit 20 has a document reading function for transporting and reading a document from the document feeder 21 and a document reading function for scanning and reading a stationary document placed on the document placing table 27.
[0022]
The paper storage unit 30 includes a plurality of paper storage units that can be individually inserted into and removed from the image forming apparatus main body. The paper storage units are paper feed trays 31a, 31b, and 31c in the illustrated example.
(2) Embodiment 1
A sheet conveying apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 2 shows the paper conveying apparatus according to Embodiment 1 of the present invention, which constitutes the paper discharge unit of the image forming apparatus shown in FIG. 3 and 4 show the operation of the sheet conveying apparatus according to Embodiment 1 of the present invention.
[0023]
The fixing device FX includes an entrance guide FX1, a heating roller FX2 having a fixing heat source FX4 provided therein, a pressure roller FX3, a fixing heat source FX4, and a paper discharge roller FX5.
[0024]
Reference numeral 100 denotes a fixed guide made up of a pair of guide plates, 101 and 102 are movable guides made up of a pair of guide plates, respectively, and 103 is a fixed guide made up of a pair of guide plates. Reference numeral 104 denotes a decurler as a curl correcting means for correcting the curl of the paper P. The decurler 104 includes three rollers 104a, 104b and 104c as curl correction members and a support disk 104d as a rotatable support means for supporting these rollers.
[0025]
The sheet P carrying the unfixed toner image is heated at the nip between the heating roller FX2 and the pressure roller FX3, and the fixing process is performed. Note that a heat source may also be provided in the pressure roller FX3.
[0026]
The fixed sheet P passes through the fixed guide 100, the movable guides 101 and 102, and the fixed guide 103.
[0027]
The sheet P has a curl (hereinafter referred to as “upper curl”) that forms a crest at the center on the side carrying the toner image fixed immediately before as shown in FIG. There are various types such as those having a curl that forms a valley in the central portion (hereinafter referred to as a lower curl) and those that do not curl on the side carrying the toner image fixed on the toner image, and the degree of curling is also various. That is, the paper P before image formation has a curl, and the curl may remain on the image-formed paper P, or the paper P may have a curl due to a fixing process. The curl generated by the fixing process may be curled upward or downward depending on the paper quality, moisture content, etc. of the paper P, and the degree of curl also changes.
[0028]
The movable guides 101 and 102 that are loosely coupled at the coupling portion Y are formed of a lightweight member, for example, a plastic sheet or a plurality of bars.
[0029]
When the paper P passes through the movable guides 101 and 102, the movable guides 101 and 102 are deformed as shown in FIGS. The downstream end of the movable guide 102, that is, the end closer to the fixed guide 103 is a free end and moves within the fixed guide 103.
[0030]
When the paper P enters the movable guides 101 and 102, the movable guide 101 follows the curl of the paper P and rotates about the base 101X. The amount of rotation of the movable guide 101 is changed by a variable resistor 105 as a displacement detection means. Converted to voltage. In this way, the curl of the paper P is detected in its direction (upper curl or lower curl) and the degree of curl. Thus, the movable guide 101 and the variable resistor 105 constitute a curl detecting means.
[0031]
In the curl detecting means, as shown in FIG. 3B, the position of the slider 105a that moves up and down integrally with the coupling point Y is detected as a resistance value of the resistor 105a as the displacement detecting means. Resistor 105 can also be used.
[0032]
The decurler 104 corrects the upper curl in FIG. 3A and corrects the lower curl in FIG. FIG. 4 shows a state in which the support disk 104d of FIG.
The support disk 104d rotates under the control of the control means 106.
[0033]
The control means 106 controls the support disk 104d based on the output of the variable resistor 105. Accordingly, the decurler 104 corrects the curl during the conveyance process of the paper P for the upper curled paper P, and the curler 104 of FIG. 4 for the lower curled paper P. In this state, the curl of the paper P is corrected.
[0034]
The decurler 104 is set to the non-operating state by raising the decurler 104a as indicated by the arrow W with respect to the paper P without curling.
(3) Embodiment 2
FIG. 5 shows a curl correcting means (decurler) in the paper conveying apparatus according to the second embodiment of the present invention. A decurler 110 corrects the upper curl and includes a displacement roller 110a, belt support rollers 110b and 110c, and a belt 110d. A decurler 111 corrects the lower curl and includes a movable roller 111a, belt support rollers 111b and 111c, and a belt 111d.
[0035]
The movable rollers 110a and 111a move up and down as indicated by arrows as controlled by the control means 106 in FIG. 2, and the movable roller 110a is set at the position of the solid line to correct the upper curl for the upper curled paper. The movable roller 111a is in the position of the dotted line, and the decurler 111 does not correct the curl. For the lower curled paper, the movable roller 110a is in the dotted line position and the decurler 110 does not perform curl correction, but the movable roller 111a is set in the solid line position and the decurler 111 performs curl correction. It is driven by a motor or solenoid (not shown) controlled by the movable rollers 110a and 111a control means 106.
[0036]
In the case where the positions of the movable rollers 110a and 111a are continuously changed to correct the curl according to the degree of curl, it is desirable that the movable rollers 110a and 111a are driven and displaced by a motor.
(4) Embodiment 3
FIG. 6 shows a sheet conveying apparatus according to Embodiment 3 of the present invention.
[0037]
In the figure, 120 is a fixed linear lower guide, and 121 is a fixed upper guide formed in a mountain shape for loop formation. A decurler 124 includes rollers 124a, 124b, and 124C, and the roller 124a is movable in the arrow W direction.
[0038]
Reference numeral 125 denotes a sensor as a loop detection means comprising a light transmitter 125a and a light receiver 125b, which outputs a signal when a predetermined amount of loop is formed. The roller 124a is moved to the position shown in the figure by the loop detection signal of the sensor 125. Then, curl correction is performed, but when the loop is not detected, the roller 124a moves in the W direction, and the decurler 124 becomes inoperative.
[0039]
As described above, in the present embodiment, only the loop in one direction of the paper P is detected as the presence or absence of the loop, and the decurler 124 performs the curl correction by the two-stage operation of operation / non-operation.
[0040]
The sheet conveying apparatus described above is an example in which the sheet conveying apparatus is provided in the image forming apparatus, but the sheet conveying apparatus according to the embodiment of the present invention may be provided in the post-processing apparatus 40.
[0041]
【The invention's effect】
According to the invention described in any one of claims 1 to 5-7, since the curl correcting means corrects the curl according to the curl of the sheet, setting of the curl correcting means that requires time such as trial baking as in the prior art. No operation is required, and the paper on which the image has been formed is always discharged to the paper discharge unit with a finished curl.
[0042]
According to the invention of claim 2 or 3, since the curl can be detected with a simple mechanism and without significantly increasing the cost and without increasing the size of the apparatus, the conventional paper conveyance is possible. The curl detection means can be provided with a slight change in the apparatus.
[0043]
The invention according to any one of claims 4 to 7 makes it possible to provide a curl correcting means capable of correcting curl in any direction in a narrow space. A device such as a paper transport device is realized.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an image forming apparatus and a post-processing apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a sheet conveying device according to a first embodiment of the present invention.
FIG. 3 is a diagram illustrating an operation of the sheet conveying device illustrated in FIG. 2;
FIG. 4 is a diagram illustrating an operation of the sheet conveying device illustrated in FIG. 2;
FIG. 5 is a diagram showing curl correction means in the paper conveying apparatus according to the second embodiment of the present invention.
FIG. 6 is a diagram illustrating a sheet conveying device according to a third embodiment of the present invention.
[Explanation of symbols]
100, 103, 112 Fixed guide 101, 102 Movable guide 104, 110, 111, 124 Decaler 105 Variable resistor 125 Sensor

Claims (6)

Curl detection means for detecting paper curl,
A curl correction means having three rollers and a support means that supports and rotates these rollers, and the direction of curl correction changes by rotation of the support means;
A pair of fixed guides for guiding the paper in the curl correcting means;
A paper conveying apparatus comprising: a control unit that controls the curl correcting unit by rotating the support unit based on the output of the curl detecting unit .   The paper conveying apparatus according to claim 1, wherein the curl detection unit includes a movable guide that is displaced following the curl of the paper, and a displacement detection unit that detects a displacement amount of the movable guide. The sheet conveying apparatus according to claim 2, wherein the displacement detection unit includes a variable resistor whose resistance value changes according to the displacement of the movable guide. An image forming apparatus comprising the sheet conveying device according to claim 1. The image forming apparatus according to claim 4 , further comprising an image forming unit and a fixing device, wherein the paper transport device transports the paper that has passed through the fixing device. A post-processing apparatus comprising the sheet conveying apparatus according to claim 1.

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