JPH11268856A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of recording paper and to resolve the occurrence of a jam and irregular paper discharge by providing a humidity detecting means detecting the environmental humidity and a curl correcting means correcting the curl of the recording paper, and operating the curl correcting means for the recording paper in response to the output of the humidity detecting means. SOLUTION: The output signal of a humidity sensor 30 is fed to a control device during image formation, and a curl correcting means is operated when the detected humidity θ lies on the outside of a fixed range in which recording paper P has a possibility to cause a curl or when the curl degree α is larger than the prescribed curl degree α0 . A conveyance path switching member 25 is operated to guide the recording paper P toward a double-face copying unit (ADU) 24, and blast fans 32, 33 are operated. A recording paper conveyance path is formed on which the recording paper P conveyed from a fixing device 22 passes through a paper feed section D, the transfer electrode 19 and separation electrode 20 of an image formation section, and the fixing device from the ADU 24 and is discharged to a recording paper discharge tray 26, thereby the curl correction of the recording paper P is conducted.

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, and more particularly to an image forming apparatus for forming an image by an electrophotographic method.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image by an electrophotographic system, heat and pressure are generally applied to a recording material on which a toner image is formed by a heat roller fixing device to fix the toner image. It is.

In such a fixing method, the recording material tends to be easily deformed during the fixing process. Such deformation of the recording material is not so noticeable in normal image formation, and no special measures are usually taken for such a phenomenon. However, in the case of double-sided image formation, if the recording material having a toner image formed on one side is deformed when the recording material is passed through the image forming apparatus again, jams are likely to occur, and the recording material may be wrinkled. In order to cause the curl of the recording material, a curl correcting unit for correcting the curl of the recording material is provided in the recording material conveying path for forming a double-sided image, and after the deformation of the recording material is corrected, an image is formed on the other surface. I have.

[0004]

As described above, there was no practical problem even if no means for correcting the deformation of the recording material was adopted except for the double-sided image formation. Depending on the quality of the recording material used, deformation of the recording material becomes a problem that cannot be ignored.

That is, a jam occurs due to the curl of the recording material, and the discharge state becomes irregular. In particular, if the range of usable recording materials is widened to reduce the printing cost, these problems become remarkable.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-described problems, and to provide an image forming apparatus which prevents a recording material from being deformed and causes less occurrence of jams and irregular discharge. .

[0007]

The object of the present invention is as follows.
(1) It has a humidity detecting means for detecting environmental humidity and a curl correcting means for correcting the curl of the recording material, and the curl correcting means acts on the recording material in accordance with the output of the humidity detecting means. An image forming apparatus, and (2) a curl detecting unit for detecting curling of the recording material that has passed through the fixing device, and a curl correcting unit for correcting the curl of the recording material. The image forming apparatus is characterized in that the curl correcting means acts on the recording material according to the output.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of a digital copying machine according to an embodiment. This digital copying machine includes an image reading unit A, an image forming unit B, an image writing unit C, a paper feeding unit D, and an automatic document feeder ADF.

In the image reading section A, an original is placed on an original platen glass (hereinafter, referred to as a platen glass) 11, and a carriage 1 that moves on a guide rail (not shown).
2 is illuminated by a light source 121 provided in the light source 2. The movable mirror unit 13 provided with a pair of mirrors 131 and 132 moves on a slide rail, and in combination with a mirror 122 provided on the carriage 12, reflected light from a document on the platen glass 11, that is, Optical image,
It is led to the lens reading unit 14. The lens reading unit 14 includes an imaging lens 141 and a CCD line sensor 142. Mirrors 122, 131, 1
The optical image corresponding to the image of the original reflected by 32 is
The light is converged by the imaging lens 141 and is imaged on the light receiving surface of the CCD line sensor 142.
Thus, the optical images on the lines are sequentially photoelectrically converted into electric signals.

When a user presses a copy button (not shown) provided on an operation unit (not shown), a light source 121 driven in conjunction with a motor (not shown) and a carriage 12 provided with a mirror 122 are provided. Movable mirror unit 1
The image information of the original of one page is read by the CCD line sensor 142 by the movement of the step (3).

An image signal of the original image read by the image reading unit A, that is, image data, is converted by an image processing unit (not shown) into a density conversion, a filtering process, a scaling process, and γ.
After various image processing such as correction is performed, the image is output to the image writing unit C via an image storage unit (not shown). And
The image writing unit C forms a latent image on the photosensitive drum 16 of the image forming unit B that forms an image by an electrophotographic method according to the input image data. That is, the image writing unit C modulates a laser beam generated by a semiconductor laser (not shown) based on an image signal. The laser beam is rotationally scanned by a polygon mirror 15 rotated by a drive motor (no sign), passes through an fθ lens (no sign), and is bent by a reflection mirror (no sign) to form an optical path on the surface of the photosensitive drum 16. To form an electrostatic latent image on the uniformly charged photosensitive drum 16.

On the other hand, the photosensitive drum 1
6, a charger 17 for uniformly charging the photosensitive drum 16, a developing unit 18, a transfer pole 19, a separation pole 20, a cleaning device 21, and a fixing device 22 are provided. In the figure, the photosensitive drum 16 rotating clockwise is connected to the charger 1.
7 and the image writing section C as described above.
Thus, an electrostatic latent image is formed. The electrostatic latent image formed on the photoreceptor drum 16 is developed by the developing device 18 to become a toner image, and the toner image is further transferred by the transfer pole 19 onto the recording paper P separately transported. The transferred recording paper P is separated by the separation pole 20 and the fixing device 22
As a result, the toner image is fixed on the recording paper P, so that a copy image of the document is obtained. The photosensitive drum 16 on which the toner image has been transferred to the recording paper P continues to rotate, is cleaned by the cleaning device 21, and is ready for the next toner image formation.

The paper feeding means D includes paper feeding cassettes 23a to 23d for storing recording paper P for each size or direction, and a duplex copying unit (ADU) for reversing the front and back of the recording paper P when performing double-sided copying. 24, each paper cassette 23a-
Conveyance roller for feeding recording paper P from 23d (no sign)
Paper feed cassette 23, which is constituted by a paper belt or a conveying belt (without a sign) and according to an instruction of the recording paper size or direction.
a to 23d, the recording paper P is taken out, synchronized with the toner image on the photosensitive drum 16,
Supplied to.

In the case of single-sided copying, the sheet cassette 23a
The toner images are sequentially transferred and fixed to one side of the recording paper P taken out from the recording paper P to the recording paper discharge tray 26. On the other hand, in the case of double-sided copying, the recording paper P fed with the toner image transferred and fixed on one side is turned downward by the transport path switching member 25 disposed immediately after the fixing device 22 in the recording paper transport path. Then, it is guided to ADU24. The ADU 24 reverses the transport direction of the transported recording paper P, and further reverses the recording paper P, so that the recording paper P is reversed upside down. Will be fed. Then, the toner image formed based on the image data on the back side of the document is transferred and fixed to obtain a double-sided copy.

The digital copying machine of the present embodiment employs recording paper P
After the sheet passes through the fixing device 22, measures are taken against curling. That is, the humidity sensor 30 that detects the environmental humidity below the image writing unit C, the fixing device 2
2, the curl detection sensor 31 and the transport path switching member 25 downstream of the recording paper transport direction and AD
A curl correcting means is provided in U24.

The environmental humidity is a factor that greatly affects the curl of the recording paper P. When the environmental humidity is extremely high or low, the recording paper P that has been subjected to the fixing process largely curls. The humidity sensor 30 is a sensor that obtains humidity information in order to prevent such curling due to humidity. The curl detection sensor 31 detects the degree of curl of the recording paper P after fixing, and conveys the recording paper P so as to detect the recording paper P floating above a predetermined height h from the conveyance surface of the conveyance path by the curl after fixing. An optical sensor including a light receiving device and a light emitting device disposed on both sides of the path, and outputs a curl detection signal when the recording paper P curls and floats from the conveyance surface.

A blower fan 32 as a curl correcting means;
33 blows air on the recording paper P to correct the curl. Further, the belt / roller unit 34 as a curl correcting means is composed of a pair of rollers, a belt stretched over them, and a curl correcting roller for pressing the belt to correct the curl of the recording paper P passing therethrough. You.

Next, the operation of the digital copying machine according to this embodiment will be described with reference to FIG.

This digital copying machine has three modes for curl correction.

Mode 1 is a mode in which the curl correcting means is operated unconditionally.

Mode 2 is a mode in which curl correction is not performed unconditionally.

Under the conditions of use of the copying machine, that is, the temperature and the humidity are controlled, and the recording paper P hardly curls under the condition that the recording is performed exclusively using the designated high-quality recording paper. In such an environment, this mode 2 is selected.

Mode 3 is a mode in which the environment humidity and the degree of curl are detected, and the curl correcting means is operated according to the detection result.

When mode 2 is selected in step S1, image formation (S6) is performed without operating the curl correcting means, as is apparent from FIG.

When the mode 3 is selected, the output of the humidity sensor 30 is observed, and if the humidity θ is within the fixed range θ _{1 to} θ ₂ where the possibility of the recording paper P curling is low, then The curl degree α is found (step S2-2). If the curl degree is equal to or smaller than the predetermined value α ₀ , image formation (S6) is performed without operating the curl correcting unit.

When the mode 1 is selected, when the humidity θ is out of the fixed range θ _{1 to} θ ₂ or when the curl degree α is larger than α ₀ , the curl correcting means is used. Operate. That is, the transport path switching member 25 operates so that the recording paper P moves toward the ADU 24, and the blowing fans 32 and 33 operate. As a result, the recording paper P transported from the fixing device 22 is transferred from the ADU 24 to the paper feeding unit D.
Then, a recording paper transport path is formed that passes through the transfer pole 19, the separation pole 20, and the fixing device 22 of the image forming unit and is discharged to the recording paper discharge tray 26.

Next, an image is formed in step S4. In this image formation, the recording paper P supplied from the paper supply unit D passes through the image forming unit, and a toner image is formed thereon. Transported to After the paper is again fed from the ADU 24, the paper passes through the transfer pole 19, the separation pole 20 and the fixing device 22 and is discharged to the recording paper discharge tray 26. Of course, no image formation is performed when such recording paper P is re-passed. In this re-passing, the blower fan 3
The curl of the recording paper P is corrected by the curl correcting action by the rollers 2 and 33 and the curl correcting action by the belt / roller unit 43.

In forming a large number of images, the transport path switching member 25 repeats the position where the recording paper P is discharged to the recording paper discharge tray 26 and the position where the recording paper P is directed to the ADU 24 for each image formation.

When the formation of a predetermined number of images is completed, that is, when the last recording paper P is discharged to the recording paper discharge tray 26 (step S5), the curl correcting means stops, that is, the blowing fans 32, 33. Stops and the curl straightening program ends.

In the double-sided image formation, the recording paper P
In each backside image formation, the recording paper P having the toner images formed on both sides is straightened because the paper is conveyed through the conveyance path passing through the ADU 24 and the curling is corrected by the blowing fans 32 and 33 and the belt / roller unit 34. It is not necessary to pass through the transport path provided with the blowing fans 32 and 33 only for the purpose, and after the image is formed on both sides, the recording paper P is discharged directly from the fixing device 22 to the recording paper discharge tray 26. You.

(2) Second Embodiment FIG. 3 shows a recording paper conveyance path after fixing, which is a main part of the second embodiment.

As shown in the figure, a transport path A provided with a curl correcting means and a transport path B which is not provided are provided, and are switched by a transport path switching member 25.

In the transport path A, a belt as a curl correcting means constituted by a transport belt 40 stretched around a driving roller 41 and a driven roller 42 and a curl correcting roller 43 is provided.
A roller unit is provided. When the recording paper P passes between the transport belt 40 and the curl correcting roller 43, the curl is corrected. Also in this embodiment, the switching member 25 operates according to the mode switching, the humidity detected by the humidity sensor 30, or the curl detected by the curl detecting means 31, in the same manner as in the first embodiment. Then, the transport path A or B is selected.

Further, in the case of double-sided image formation, since the curl correction has been performed in the process of transporting the recording paper for the double-sided image formation as described above, it is not necessary to perform the curl correction in the paper discharge section. Therefore, in the case of double-sided image formation, the path is switched to the conveyance path B.

(3) Third Embodiment FIG. 4 shows a recording paper conveyance path after fixing, which is a main part of the third embodiment.

As in the second embodiment, a curl correcting unit is provided in the recording paper conveyance path after fixing. As the curl correcting means, similarly to the second embodiment, the transport belt 40, the driving roller 41, the driven roller 42, and the curl correcting roller 4
3 is a fixing device 2
2 downstream.

When the curl correction is not performed, the curl correction roller 43 rises to the position 43U indicated by the dotted line, and the recording paper P moves straight on the transport belt without receiving the correction force. Whether or not to activate the curl correcting means is selected according to the mode switching, the detected humidity, or the detected curl degree, as in the first embodiment.

[0038]

As described above, the curl of the recording material caused by the fixing is prevented, and the recording material is prevented from being ejected without being jammed or being irregularly arranged on the recording paper discharge tray, thereby realizing a highly reliable image forming apparatus.

In particular, paper of poor quality can be used, which helps to reduce printing costs.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a digital copying machine according to a first embodiment of the present invention;

FIG. 2 is a flowchart of an operation program of the digital copying machine shown in FIG.

FIG. 3 is a diagram showing a main part of a second embodiment of the present invention.

FIG. 4 is a diagram showing a main part of a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 30 humidity sensor 31 curl detection sensor 32, 33 blower fan (curl correcting means) 43 curl correcting roller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 21/00370 G03G 21/00370

Claims (8)

[Claims] 1. A printer comprising a humidity detecting means for detecting environmental humidity and a curl correcting means for correcting curl of a recording material, wherein the curl correcting means acts on the recording material in accordance with an output of the humidity detecting means. An image forming apparatus comprising: A curl detecting unit for detecting a curl of the recording material that has passed through the fixing device; and a curl correcting unit for correcting the curl of the recording material. An image forming apparatus wherein the curl correcting means is operated. A first mode in which an image is formed by using the curl correcting means; and when the first mode is selected, the curl correcting means is operated regardless of an output of the humidity detecting means. The image forming apparatus according to claim 1, wherein the image is formed by causing the image to be formed. 4. A first mode in which an image is formed using the curl correcting means, and when the first mode is selected, the curl correcting means is operated regardless of an output of the curl detecting means. The image forming apparatus according to claim 2, wherein the image is formed by causing the image to be formed. 5. A second mode in which image formation is performed without using the curl correcting unit, and when the second mode is selected, the curl correcting unit is disabled regardless of an output of the humidity detecting unit. The image forming apparatus according to claim 1, wherein the image forming is performed by operating the image forming apparatus. 6. A second mode in which an image is formed without using the curl correcting means, and when the second mode is selected, the curl correcting means is disabled regardless of an output of the curl detecting means. The image forming apparatus according to claim 2, wherein the image forming is performed by operating the image forming apparatus. 7. The image forming apparatus according to claim 1, wherein the curl correcting unit is provided between the fixing device and the recording sheet discharge tray in a recording material conveying direction path, and disables the curl correcting unit during double-sided image formation. The image forming apparatus according to any one of claims 1 to 6. 8. A printing apparatus comprising: a first transport path having the curl correcting unit; a second transport path not having the curl correcting unit; and a transport path switching unit for selecting one of the two transport paths. The image forming apparatus according to claim 1.