JP4796991B2 - Recording paper transport device, image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a recording medium, and a recording paper conveyance device that can be used therefor.

  An example of the sheet passing device provided in the image forming apparatus has a structure in the vicinity of the discharge unit 80 as shown in FIG. In the figure, 70 is a fixing means, 84 is a branching member, and 85 is a filler type recording paper detecting means. In the illustrated example, since the curvature of the switching branch point 81 is tight, the toner image is scraped off when the recording paper P is strongly slidably contacted with the branching member 84 when the recording paper P having a strong stiffness is passed. Problems such as adhesion and deposition occur. This causes a problem of paper jam (JAM).

  When performing double-sided recording, when the trailing edge of the recording paper P on which image formation on the first side has finished passes through the switching branch point 81, the conveyance direction of the discharging means 80, which is the reversing means, is reversed to perform recording. When the front end and the rear end of the paper P are switched and transported to the double-sided transport path 82, there is a problem that if the transport assisting member 83 is fixed, the recording paper P is caught by the transport assisting member 83 and becomes JAM.

JP 2004-075305 A Japanese Patent Laid-Open No. 03-279155 JP 05-097305 A JP 2003-252508 A

  In view of these conventional problems, the present invention facilitates the sliding contact of the recording paper with the branching member, and suppresses the phenomenon of the toner image being scraped off, the problem of toner adhesion, accumulation, and the trapping of the double-sided conveyance path. An object of the present invention is to provide a recording paper transport device and an image forming apparatus that can prevent paper jams.

  According to a first aspect of the present invention, there is provided a recording paper conveying apparatus provided with a recording paper conveying means for conveying the discharged recording paper in a paper discharge direction or in a direction opposite to the paper discharge direction. A conveyance auxiliary member that smoothly conveys the recording paper is provided at the recording paper sliding contact portion of the branch member that switches the paper conveyance direction to the paper discharge direction or the direction opposite to the paper discharge direction, and the conveyance auxiliary member moves in the paper discharge direction. It is possible to make it possible.

  According to a second aspect of the present invention, in the recording paper conveyance device according to the first aspect, the conveyance auxiliary member is a rotating member that rotates in sliding contact with the recording paper.

  According to a third aspect of the present invention, in the recording paper conveyance device according to the first or second aspect, the conveyance auxiliary member is capable of moving in the paper discharge direction in contact with the recording paper.

  According to the fourth aspect of the present invention, in the recording paper conveying apparatus according to the first or second aspect, the conveyance assisting member is linked with a filler type recording paper detecting means for detecting a conveying state of the recording paper, and is discharged. It is possible to move in the direction.

  According to a fifth aspect of the present invention, in the recording paper conveyance device according to any one of the first to fourth aspects, the conveyance auxiliary member is formed of an elastic material.

  According to a sixth aspect of the present invention, in the recording paper conveyance device according to any one of the first to fifth aspects, the conveyance auxiliary member is formed of a material having excellent separability with respect to toner.

  According to a seventh aspect of the present invention, in the recording paper conveyance device according to any one of the first to sixth aspects, a plurality of the conveyance auxiliary members are provided.

  According to the eighth aspect of the present invention, in the recording paper conveyance device according to any one of the first to seventh aspects, the conveyance auxiliary member is disposed between the fixing unit and the recording paper discharge unit of the image forming apparatus. Features.

  According to the ninth aspect of the present invention, in the recording paper conveyance device according to any one of the first to eighth aspects, the conveyance auxiliary member is provided in the branch member.

  An image forming apparatus according to claim 10 includes the recording paper conveyance device according to any one of claims 1 to 9, and further includes a fixing unit that fixes the toner image transferred to the recording paper by heating and pressing. Features.

  According to an eleventh aspect of the present invention, in the image forming apparatus of the tenth aspect, the auxiliary conveyance member is provided on the side opposite to the image surface of the recording paper conveyance path.

  INDUSTRIAL APPLICABILITY According to the present invention, in a recording paper conveyance device and an image forming apparatus, a phenomenon that a toner image is scraped off, toner adhesion, accumulation, and a problem of a double-side conveyance path catching can be suppressed with a simple structure, and a paper jam can be prevented. There is.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

  FIG. 2 is a cross-sectional view schematically showing a color image forming apparatus in which four image forming units each having one developing device are arranged on the periphery of the image carrier, and the developing device is mounted on the image forming apparatus main body. And a state where the image carrier unit is mounted.

The main part of this color image forming apparatus will be described with reference to FIG.
Four image forming units are arranged substantially in the center of the color image forming apparatus, and a sheet feeding unit 4 is arranged immediately below the image forming unit. A paper discharge storage unit 5 is formed above the image forming unit, and the recording paper P on which an image is formed is discharged and stored.

  The paper feeding unit 4 is provided with a stacking unit 41 that accommodates unused recording paper P. The stacking unit 41 leaves the paper feeding roller 42, the recording paper presence / absence detecting means 45, etc. Is detachably arranged in the right direction. In the paper feeding unit 4, the recording paper P is separated one by one by the paper feeding roller 42 and the friction pad 43, conveyed to the registration roller 60, and the leading edge of the paper hits the registration roller 60 to perform leading edge alignment. The registration roller 60 temporarily stops the conveyance of the sheet and controls the rotation so as to start at a timing so that the positional relationship between the toner image on the intermediate transfer belt 28 and the leading edge of the sheet becomes a predetermined position.

  The developing device includes four developing units 31 (31a, 31b, 31c, 31d) each containing toner of different colors as a developer, and an image carrier drum 22 (22a, 22b, 22) arranged in combination with these developing units. 22c, 22d). Around the image carrier drum 22, a cleaning blade 23 (23a, 23b, 23c, 23d) for scraping residual toner after the primary transfer, and a charging roller 21 (21a, 21b, 21c) contacting the image carrier drum 22 are provided. 21d).

  In this embodiment, an image carrier unit 20 (20a, 20b, 20c, 20d) in which these are integrated is configured. The housing of the image carrier unit is configured to be able to incorporate a developing device. In addition, there is an intermediate transfer unit including an intermediate transfer belt 28 that circulates around a driving roller 26, a driven roller 27, and a primary transfer roller 29 (29a, 29b, 29c, 29d) that are in contact with each other. .

  A negative bias voltage in which alternating current and direct current are superimposed is applied to a cored bar of the developing roller 32 of each developing device 31 from a bias power source (not shown). Further, a DC negative potential bias voltage is applied to each charging roller 21 from another bias power source. An image forming unit is formed by the image carrier drum 22 combined with the developing unit 31 described above, the cleaning blade 23 in contact with the image carrier drum 22 and the charging roller 21, and 20a is a first image forming unit and 20b is a second image. An image forming apparatus having four image forming units, such as a forming unit, 20c a third image forming unit, and 20d a fourth image forming unit.

  The cleaning blade 23a cleans toner stains remaining on the peripheral surface of the image carrier drum 22a. The charging roller 21a is initialized by charging the cleaned peripheral surface of the image carrier drum 22a to a uniform high potential. Then, the laser beam 36a is applied to the image carrier drum 22a of the first image forming unit. The image carrier drum 22b of the second image forming unit is irradiated with a laser beam 36b. As a result, the peripheral surface of the image carrier drum 22a charged to the uniform high potential is selectively exposed based on the image data, and the low potential portion where the potential is attenuated by this exposure and the high potential due to the initialization. An electrostatic latent image consisting of a portion is formed. This operation is performed up to the fourth forming portion.

  The developing device 31a forms (develops) a toner image by transferring toner to the low potential portion (or high potential portion) of the electrostatic latent image. The image carrier drum 22 a rotates and conveys the toner image and transfers it to the intermediate transfer belt 28.

  The second image forming unit operates in the same manner as described above in accordance with the timing at which the toner image on the intermediate transfer belt 28 comes into contact with the image carrier drum 22b. The electrostatic latent image on the drum 22b is converted into a toner image (development), and the image carrier drum 22b rotates and conveys the toner image and superimposes and transfers the toner image on the intermediate transfer belt 28. The same operation is performed up to the fourth forming portion.

  A quadruple toner image is conveyed as in the above operation, and the toner image is transferred to a recording paper P (not shown) by a secondary transfer roller 39.

  Thereafter, the image is fixed by the fixing means 70, and in the case of single-sided recording, it is discharged and stacked in the discharge storage portion 5 formed on the upper surface of the apparatus main body 1 by the discharge means 80.

  When performing double-sided recording, when the trailing edge of the recording paper P on which image formation on the first surface has finished passes through the switching branch point 81, the conveyance direction of the discharging means 80, which is the reversing means, is reversed, and the recording paper P The front end and the rear end are switched and conveyed to the double-sided conveyance path 82. The recording paper P is conveyed again to the registration roller 60 through the refeed path 44 provided in the stacking unit 41, and the toner image on the second surface is transferred by the secondary transfer roller 39. After being fixed, the discharge means 80 discharges it to the discharge storage portion 5.

  In this embodiment, as shown in FIGS. 3A and 3B, after the image is fixed by the fixing unit 70, the leading edge of the recording paper P abuts on the conveyance auxiliary member 83 and moves in the paper discharge direction. Then, it is brought into sliding contact with the recording paper P, thereby being rotated together with the recording paper P. Further, the outer surface of the conveyance auxiliary member 83 is provided so as to protrude from the conveyance surfaces on both the upper and lower sides of the branch member 84. As a result, the recording paper P sent from the fixing unit 70 comes into contact with the conveyance auxiliary member 83 at the branch member 84. When the trailing edge of the recording paper P moves away from the conveyance assisting member 83, the conveyance assisting member 83 returns to the standby position in FIG.

  4 (A) and 4 (B) show a second embodiment of the present invention. In this embodiment, after being fixed by the fixing means 70, the conveyance auxiliary member 83 is linked with the operation of lifting the filler type recording paper detection means 85 for detecting the conveyance state of the recording paper P after the leading edge of the recording paper P is detected. Is moved in the paper discharge direction, slidably contacts the recording paper P, and is rotated together with the recording paper P. Further, the outer surface of the conveyance auxiliary member 83 is provided so as to protrude from the conveyance surfaces on both the upper and lower sides of the branch member 84. As a result, the recording paper P sent from the fixing unit 70 comes into contact with the conveyance auxiliary member 83 at the branch member 84. When the trailing edge of the recording paper P moves away from the conveyance assisting member 83, the conveyance assisting member 83 returns to the standby position shown in FIG.

  Although illustration is omitted, not only a roller but also a roller, a spur, and the like can be used as the conveyance auxiliary member. In addition, a material excellent in releasability with respect to toner, to which a fluorine resin or a fluorine coating is applied can be used. Furthermore, the apparatus can be configured by using a plurality of conveyance auxiliary members.

Schematic cross-sectional view showing a conventional example of a sheet passing device provided in an image forming apparatus 1 is a schematic cross-sectional view of an example of an image forming apparatus that is an object of the present invention. 1 is a schematic cross-sectional view showing a first embodiment of a sheet passing apparatus provided in a recording sheet conveying apparatus and an image forming apparatus according to the present invention. FIG. 3 is a schematic cross-sectional view showing a second embodiment of the sheet passing apparatus provided in the recording sheet conveying apparatus and the image forming apparatus according to the present invention.

Explanation of symbols

1: apparatus main body 4: paper feeding unit 5: paper discharge storage unit 20a: first image forming unit 20b: second image forming unit 20c: third image forming unit 20d: fourth image forming unit 21: charging roller 22: image Carrier drum 23: Cleaning blade 26: Driving roller 27: Driven roller 28: Intermediate transfer belt 29: Primary transfer roller 31: Developer 32: Developing roller 36a, 36b: Laser beam 39: Secondary transfer roller 41: Loading unit 42: Paper feed roller 43: Friction pad 44: Refeed path 45: Recording paper presence / absence detection means 60: Registration roller 70: Fixing means 80: Discharge means 81: Switching branch point 82: Double-sided conveyance path 83: Conveyance auxiliary member 84: Branch member 85: Filler type recording paper detection means P: Recording paper

Claims (11)

Recording paper transporting means for transporting the discharged recording paper in the paper discharge direction or in the direction opposite to the paper discharge direction;
Provided in the recording paper conveyance path is a conveyance auxiliary member that smoothly conveys the recording paper at the recording paper sliding contact portion of the branching member that switches the conveyance direction of the recording paper to the discharge direction or the direction opposite to the discharge direction,
A recording paper transport apparatus, wherein the transport auxiliary member is movable in a paper discharge direction.   2. The recording paper conveying apparatus according to claim 1, wherein the auxiliary conveying member is a rotating member that rotates in sliding contact with the recording paper.   3. The recording paper conveying apparatus according to claim 1, wherein the auxiliary conveying member is brought into contact with the recording paper and can be moved in the paper discharging direction.   3. The recording paper conveying apparatus according to claim 1, wherein the auxiliary conveying member is movable in a paper discharge direction in conjunction with a filler type recording paper detecting means for detecting a recording paper conveying state. Recording paper transport device.   5. The recording paper transport apparatus according to claim 1, wherein the transport assisting member is made of an elastic material.   6. The recording paper transport apparatus according to claim 1, wherein the transport assisting member is formed of a material having excellent separability with respect to toner.   7. The recording paper transport apparatus according to claim 1, comprising a plurality of the transport auxiliary members.   8. The recording paper conveyance device according to claim 1, wherein the conveyance auxiliary member is disposed between a fixing unit and a recording paper discharge unit of the image forming apparatus.   9. The recording paper transport apparatus according to claim 1, wherein the branching member is provided with the transport auxiliary member.   An image forming apparatus comprising: the recording paper conveyance device according to claim 1, and a fixing unit that fixes the toner image transferred to the recording paper by heating and pressurizing. The image forming apparatus according to claim 10, wherein the conveyance auxiliary member is provided on the side opposite to the image surface of the recording paper conveyance path.