JP2004026388A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device equipped with a feed roller capable of dispensing with calculation of the quantity of the curled parts of a recording paper sheet in advance in accordance with circumference environment or the kind of the recording paper sheet, and capable of promptly correcting the curl of the recording paper sheet even when the circumference environment or the kind of the recording paper sheet varies. <P>SOLUTION: The feed roller arranged on a paper feeding port part of a fixing unit provided with a heating roller and a pressure roller rotating while being brought in pressure-contact with each other is divided into roller groups having different diameters. The recording paper sheet fed from a nip position of the heating roller and the pressure roller is delivered in a condition that the recording paper sheet is wavy along the direction crossing the feeding direction at right angles. The feed roller on both side end parts is movable along a roller axial direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus represented by a copier, a printer, and a facsimile machine, and more particularly, to curling of a recording sheet passing through a fixing unit for fixing a toner image transferred to the recording sheet. The present invention relates to a correction feed roller.
[0002]
[Prior art]
Generally, in an image recording apparatus such as a copying machine, a printer, and a facsimile apparatus, a toner image transferred to recording paper by a recording unit is fixed by a fixing unit to be a permanent image. Conventionally, a fixing device of this type includes a heating roller and a pressure roller that rotate while being pressed against each other, and a recording sheet on which an unfixed toner image is formed is inserted between these rollers to fix the unfixed toner image. It is something to do.
[0003]
However, in this type of fixing device, when the recording paper is inserted between the heating roller and the pressure roller, the temperature of the heating roller side surface of the recording paper becomes higher than that of the pressure roller side rear surface. When the recording paper curls, the stacking property (stackability) of the recording paper on the discharge tray or intermediate tray is impaired after passing through the fixing device, or a jam occurs due to the curl of the recording paper during duplex copying. I do.
[0004]
It is also known that the intensity and direction of the curl generated on the recording paper vary depending on the surrounding environment such as temperature and humidity, the paper quality, particularly the moisture content of the paper, and the like.
[0005]
In order to avoid such a situation, generally, the diameter of the paper discharge roller disposed immediately after the fixing device is set to be a combination of large and small, and a plurality of paper discharge rollers are provided in a staircase, so that the fold is formed in the paper transport direction. By providing the recording paper, the recording paper which is going to be curled while warping is given stiffness to prevent the curling. In the example described in JP-A-8-290857, for example, a pair of discharge rollers is disposed downstream of the heating roller and the pressure roller in the direction of conveyance of the recording paper. There is provided a printer in which the position of the discharge roller relative to the nip position of the heating roller and the pressure roller is changed by variably setting the vertical position to correct the curl of the recording paper.
[0006]
[Problems to be solved by the invention]
However, in the conventional example in which the discharge rollers having different diameters are arranged in a stepped manner, the roller is fixed to the image forming apparatus main body, and the roller is fixed. For this reason, although it has a modest effect on curling in the case where standard recording paper is used in a standard usage environment, the surrounding usage environment such as temperature and humidity changes, and If the type changes, no satisfactory effect is obtained.
Further, in an example in which the position of the nip point of a discharge roller composed of a pair of rollers is changed from the measured temperature of the pressure roller as described in JP-A-8-290857, It is necessary to determine the amount of curl of the recording paper according to the temperature in advance. Further, it is necessary to determine the amount of change in the nip position of the discharge roller pair so that the curl amount of the recording sheet is corrected. Furthermore, it is necessary to consider the influence of the surrounding environment and paper quality on the amount of change.
[0007]
An object of the present invention is that it is not necessary to determine the curl amount of the recording paper in advance according to the surrounding environment and the type of the recording paper. It is another object of the present invention to provide an image forming apparatus including a feed roller capable of correcting the curl of a recording sheet.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an image forming apparatus having a fixing unit including a heating roller and a pressure roller which rotate while being pressed against each other. The feed roller provided is divided into a plurality of roller groups having different diameters, and the recording paper conveyed from the nip position between the heating roller and the pressure roller is made to have a wavy shape in a direction orthogonal to the conveyance direction. It is characterized in that the plurality of roller groups include a roller that is disposed so as to be movable in the roller axis direction while discharging.
[0009]
According to the invention according to claim 1 having the above configuration, by moving a part of the movable rollers to an arbitrary position in the roller axis direction, a predetermined position of the recording paper conveyed from the fixing unit is obtained. A wavy fold is made to appear in a direction perpendicular to the transport direction to impart stiffness, and it is possible to correct the curl in the transport direction generated by the heating / pressing action at the time of fixing.
[0010]
The invention according to claim 2 is characterized in that the movable roller is a single roller without a driven roller.
[0011]
According to the second aspect of the present invention having the above-described configuration, the operation of moving the driven roller or the like is not required just by moving the movable single roller, and the curl correcting operation can be easily performed.
[0012]
The invention according to claim 3 is characterized in that the movable roller is disposed at both ends of the paper discharge port.
[0013]
According to the third aspect of the present invention having the above configuration, by moving the two rollers at both ends provided at the discharge port of the image forming apparatus in the roller axis direction, the surrounding environment and the recording paper can be removed. The curl caused by the difference can be corrected.
[0014]
The invention according to claim 4 is characterized in that the movable roller has a configuration in which an elastic roller is fitted to a boss portion to which a fixing screw is attached, and the fixing screw is operable from the outside of the paper discharge port. And
[0015]
According to the invention according to claim 4 having the above configuration, the position of the curl correction roller can be changed to an optimum position from outside the apparatus. Further, even if the position change operation is repeatedly performed, the roller can be kept intact without damaging the roller.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS.
[0017]
FIG. 1A is a front view showing a discharge roller unit to which a feed roller according to an embodiment of the present invention is attached. FIG. 1B is a perspective view showing a wavy bent portion of the recording sheet that has passed through the sheet discharging roller unit shown in FIG. 2A and 2B are perspective views showing a curled state of a recording sheet according to an embodiment of the present invention, wherein FIG. 2A shows a curled recording sheet after fixing, and FIG. 4 shows a recording sheet to which a copy is given. FIG. 3 is an overall sectional view showing the inside of the image forming apparatus to which the fixing unit according to the present invention is attached. FIG. 4 is a schematic explanatory view showing a layout of each unit of the image forming apparatus.
[0018]
An image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. The image forming apparatus A includes units such as a developing unit 10, a drum unit 20, and a fixing unit 30. In particular, the developing unit 10 and the drum unit 20 are integrally and detachably configured as a process unit. At the lower part of the main body of the image recording apparatus A, a paper storage unit 60 for storing the recording paper P is provided. An ADF (automatic document feeder) 40 is provided at the upper part of the main body of the recording device A, and has a fax function and a copy function. In order to record an image on the recording sheet P, one sheet of the recording sheet P is picked up by the separation feeding means, transported in the direction of the developing unit 10, the image is transferred by the drum unit 20, and fixed by the fixing unit 30. The configuration is such that a recording sheet P on which an image has been recorded is conveyed in the direction of the discharge port B and sent to the discharge section 50.
[0019]
The developing unit 10, the drum unit 20, and the fixing unit 30, which are integrated as respective units, are configured to be detachable from the apparatus main body for maintenance or component replacement. Each of the units 10, 20, and 30 is configured such that the upper part of the apparatus main body is opened for simplicity of operability, and the unit can be freely inserted and removed from the opened upper part.
[0020]
The developing unit 10 includes a toner 15, a toner supply roller 12, a developing roller 11 disposed between the supply roller 12 and the photosensitive drum 21 and arranged at a position where the developing roller 11 is in contact with the toner 15. And a toner regulating blade 14 resiliently contacted with the peripheral surface on the downstream side in the transport direction.
[0021]
The toner supply roller 12 is disposed so as to press the developing roller 11 and the roller unit against each other, and rotates in the same direction as the developing roller 11 as indicated by an arrow in the drawing. Due to this rotational movement, the toner supply roller 12 supplies the toner 15 to the developing roller 11, frictionally charges the toner at a contact portion with the developing roller 11, and scrapes unused toner on the developing roller 11. I do.
[0022]
The drum unit 20 is provided as a unit including a photosensitive drum 21, a transfer roller 22, a charging brush 23, and a memory removing brush 24. A recording head (LED head) 25 is provided around the photosensitive drum 21. An image is written on the photosensitive drum 21 by the recording head 25, and the photosensitive drum 21 Is transferred and recorded.
[0023]
Downstream of the drum unit 20, a fixing unit 30 for fixing the toner image transferred to the recording paper P is provided. The fixing unit 30 includes a heating roller 31 and a pressure roller 32 that are pressed against each other, a discharge roller 33 that discharges the fixed recording paper P, and a separation roller that prevents the recording paper P from winding around the heating roller 31. And a nail 34.
[0024]
The recording paper P on which the image has been transferred passes through the nip between the heating roller 31 and the pressure roller 32, and is heated and pressed to fix the image and form a permanent image. The recording paper P on which the image has been fixed is discharged by a discharge roller 33 to a discharge unit 50 outside the apparatus.
[0025]
The recording paper P may be curled due to the toner that has been heated and melted in the fixing unit mainly composed of the heating roller 31 and the pressure roller 32 contracting due to air cooling after discharge. know. Further, it is also known that the curl amount and the curl position change depending on the image density (toner amount), the type of paper (material, rigidity, thickness, size, gap direction, etc.) and the surrounding environment such as temperature and humidity. I have.
[0026]
The curl generated on the recording paper P after fixing is generally in the state shown in FIG. 2A, and is a curled recording paper P2 that warps to the printing surface side. In order to correct such a curl, a discharge roller 33 disposed immediately after the fixing unit is configured as shown in FIG. That is, the feed roller that is fitted into the drive shaft 4 and rotates together with the drive shaft 4 is divided into a plurality of roller groups, and the large-diameter feed roller 1 that abuts both side edges of the recording paper P and the inside thereof are respectively disposed. And a large-diameter feed roller 2 disposed at the center portion, and the height of the feed roller that is in contact with the lower surface of the recording paper P and is conveyed is formed in a stepped shape. .
[0027]
The small-diameter feed roller 3 is provided with a driven roller 5 in a contact state, and is configured to nip and convey the recording paper P. The recording sheet P conveyed through the nip between the heating roller 31 and the pressure roller 32 is conveyed while being nipped by the sheet discharging roller 33 having a stepped roller surface. Since the feed rollers 1 and 2 having a large diameter are disposed on both sides of the feed roller 3 that nips and conveys the fixed recording paper P, the recording paper P undulates in a direction perpendicular to the conveyance direction C. A fold 1w is provided in the shape.
[0028]
Since the paper discharge roller 33 forms a plurality of wavy folds 1w in the transport direction C, the occurrence of curls that originally intend to curl upward on the printing surface side after fixing is prevented from occurring in the wavy folds in a direction perpendicular to the transport direction. This can be prevented by the stiffness of the recording paper P due to 1w. Further, it is known that the strength and direction of the curl change depending on the surrounding environment such as temperature and humidity and the type of recording paper.
[0029]
Therefore, in the present invention, the large-diameter feed roller 1 abutting on both side edges of the recording paper P is configured to be movable in the roller axis direction, and the appearance position of the wavy fold 1w according to the degree of curl strength is determined. The recording paper P can be changed so that the stiffness of the recording paper P can be changed.
[0030]
The feed roller 1 will be described with reference to FIGS. The feed roller 1 is formed by winding a roller member 1a made of an elastic body on a boss 1b, which is a wide core made of metal or hard resin, and covering a part of the boss 1b in the width direction. Roller. Further, the roller member 1a of the boss portion 1b is not wound and a threaded portion is provided at a bare portion, and the feed roller 1 is fixed to the drive shaft 4 by fixing a fixing screw 1c. is there. That is, only by loosening the fixing screw 1c, the feed roller 1 can be moved in the roller axis direction (T direction) and can be mounted again at an arbitrary position.
[0031]
The image forming apparatus A is originally assembled and shipped in a standard state, and the mounting position of the feed roller 1 is also set to a position assuming a standard surrounding environment and standard paper. However, depending on the actual use environment and the type of recording paper, the strength and position of the curl generated at the time of fixing may differ. For this reason, even in the image forming apparatus in which the feed roller 1 is set at the standard position, the curl may not be sufficiently corrected in some cases, and the curl-like recording paper P may be discharged as it is, and the stacking property may be deteriorated. There's a problem.
[0032]
Therefore, by finely adjusting the mounting position of the feed roller 1 at both end portions in the roller axis direction, the appearance position of the wavy fold 1w can be changed, and the stiffness of the recording paper P can be adjusted. That is, when it is desired to reduce the curl by increasing the stiffness of the recording paper P, the mounting position of the feed roller 1 can be moved slightly toward the center. When it is desired to reduce the stiffness of the recording paper P, the mounting position of the feed roller 1 may be moved slightly outward.
[0033]
Even in the case of the curled recording paper P2 shown in FIG. 2A, by arranging the mounting position of the feed roller 1 at an appropriate position, a loose wavy curl as shown in FIG. No recording paper P1 can be discharged.
[0034]
The work of changing the mounting position of the feed roller 1 can be performed by inserting a hand from the paper discharge unit 50 direction, and can be finely adjusted while checking the curl state of the recording paper P from outside the apparatus. Further, it is not necessary to estimate the curl amount from the surrounding environment and the type of the recording paper in advance, and the adjustment can be made while checking on the spot on the spot.
[0035]
【The invention's effect】
According to the first aspect of the present invention, a feed roller composed of a plurality of roller groups having different diameters moves a recording sheet conveyed from a nip position between a heating roller and a pressure roller in a direction orthogonal to a conveyance direction. It is assumed that the rollers are discharged while being wavy, and furthermore, the plurality of roller groups include rollers that are movably arranged in the roller axis direction. By moving the recording paper to a predetermined position on the recording paper conveyed from the fixing unit, a wavy fold appears in a direction perpendicular to the conveyance direction to impart stiffness. The curl in the transport direction generated by the heating / pressing action can be corrected.
[0036]
According to the second aspect of the present invention, since the movable roller is a single roller having no driven roller, an operation such as moving the driven roller only by moving the movable single roller. And the curl straightening operation can be easily performed.
[0037]
According to the third aspect of the present invention, since the movable rollers are provided at both ends of the paper discharge port, both ends of the movable rollers are provided at the paper discharge port of the image forming apparatus. By moving the two rollers in the roller axial direction, the appearance position of the wavy fold can be changed to adjust the stiffness of the recording paper P, and the curl generated due to the surrounding environment and the difference in the recording paper. Can be corrected.
[0038]
According to the invention according to claim 4, the movable roller has a configuration in which an elastic roller is fitted to a boss portion to which a fixing screw is attached, and the fixing screw can be operated from the outside of the paper outlet. The position of the curl correction roller can be changed to an optimum position from outside the apparatus. In addition, even if the position change operation is repeatedly performed, a stable paper discharging operation can be maintained without damaging the rollers.
[Brief description of the drawings]
FIG. 1A is a front view showing a paper discharge roller on which a plurality of divided feed rollers are mounted.
FIG. 2B is a perspective view illustrating a wavy bent portion of the recording sheet that has passed through the sheet discharging roller illustrated in FIG.
FIG. 2 is a perspective view showing a state of curling of a recording sheet according to the embodiment of the present invention,
(A) shows curled recording paper after fixing,
(B) shows a recording sheet provided with a wavy bent portion for curl correction.
FIG. 3 is an overall sectional view showing the inside of an image recording apparatus to which a fixing unit according to the present invention is attached.
FIG. 4 is a schematic explanatory diagram showing a layout of each unit of the image recording apparatus.
[Explanation of symbols]
1 feed roller (large diameter movable roller)
1a Elastic roller 1b Boss part (core metal)
1c fixing screw 2 feed roller (large diameter)
3 Feed roller (small diameter)
Reference Signs List 4 Drive shaft 5 Follower roller 10 Developing unit 20 Drum unit 30 Fixing unit 31 Heating roller 32 Pressure roller 33 Discharge roller 50 Discharge unit A Image recording device B Discharge port P Recording paper P1 Non-curled recording paper P2 Curled Recording paper

Claims (4)

In an image forming apparatus having a fixing unit including a heating roller and a pressure roller that rotate while being pressed against each other, a feed roller disposed at a discharge port of the fixing unit is divided into a plurality of roller groups having different diameters. The recording paper conveyed from the nip position between the heating roller and the pressure roller is ejected while waving in a direction orthogonal to the conveyance direction, and the plurality of roller groups are movable in the roller axis direction. An image forming apparatus, comprising: a roller disposed in the image forming apparatus. The image forming apparatus according to claim 1, wherein the movable roller is a single roller without a driven roller. The image forming apparatus according to claim 1, wherein the movable rollers are disposed at both ends of the paper discharge port. 4. The movable roller according to claim 1, wherein the movable roller has a configuration in which an elastic roller is fitted to a boss portion to which a fixing screw is attached, and the fixing screw is operable from outside of the paper discharge port. 5. An image forming apparatus according to any one of the above.

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