JP2010132372A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of restricting a temperature rise inside the device by improving stacking performance of delivered paper sheets on a delivery tray. <P>SOLUTION: This image forming device 100 includes: a fixing unit 7 for fixing a toner image, which is transferred onto a paper sheet P, to the paper sheet P; a delivery roller 12b for delivering the paper sheet P, in which image formation is concluded by fixing the toner image: the delivery tray 91, onto which the paper sheets P are to be delivered; an upper fan 31 and a lower fan 32 provided in the upstream and the downstream of the delivery roller 12b to generate an air flow above the delivery tray 91; and a rotation control means 300 for controlling rotation of the upper fan 31 and the lower fan 32. As the rotation control means 300, a function for controlling rotation of the upper fan 31 and the lower fan 32 in response to the position of the paper sheet P to be delivered onto the delivery tray 91 is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a multifunction machine, and more particularly, to an image forming apparatus provided with a plurality of blower fans to align image-formed sheets.

  Conventionally, in an image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine, the paper P on which image formation has been completed is discharged onto a paper discharge tray 291 outside the apparatus by a paper discharge roller 212 as shown in FIGS. It is supposed to be paper.

  However, the discharged paper P is in contact with the paper discharge tray 291 at the paper leading edge P1. If there is already a sheet on the paper discharge tray 291, the sheet leading end P <b> 1 presses the sheet, and the sheet alignment (stacking property) deteriorates. Further, the rear end P2 of the sheet is in contact with the side wall 291a, and the alignment of the sheet is disturbed.

  Further, since the discharged paper P is discharged onto the paper discharge tray 291 in a curled state due to the influence of heat of a fixing device (not shown), the consistency of the paper on the paper discharge tray 291 is deteriorated. There was a problem.

  Therefore, in order to improve the paper consistency of the paper P on the paper discharge tray 291, as a conventional technique, the paper P is discharged onto the paper discharge tray 291 as shown by a two-dot chain line in FIGS. 5 and 6. An upper fan 131 and a lower fan 132 are provided at the upper and lower portions of the paper discharge roller 212 to improve the consistency of the paper P by blowing air to the discharged paper P (see FIG. (See Patent Document 1).

Specifically, the lower fan 132 provided below the paper discharge roller 212 sucks the paper P discharged from the paper discharge roller 212 toward the apparatus main body, while the upper fan 131 provided above the paper discharge roller 212. Thus, the sheet P is aligned by being dropped so as to be pressed toward the side wall 291a of the discharge tray 291 which is the alignment surface.
JP 2002-114432 A

  However, in the above-described prior art, the air flow of the upper fan 131 and the lower fan 132 on the outlet side of the paper discharge roller 212 is attracted to the side wall 291a of the paper discharge tray 291 that is the alignment surface, and the alignment is improved. Although it is intended, the following problems arise.

  That is, as shown in FIG. 5, when an air current is generated on the paper P by the upper fan 131 while the paper is discharged from the paper discharge roller 212, the paper is curled downward with the nip portion of the paper discharge roller 212 as a fulcrum, The leading edge P1 is discharged toward the upper surface of the discharge tray 291. In addition, since the sheet P is drawn toward the apparatus main body by the lower fan 132, the curled leading end is drawn toward the side wall 291a of the paper discharge tray 291. This causes a problem that the curl amount is further increased and the alignment is deteriorated. .

  In addition, the paper P that is about to be dropped while being completely discharged from the paper discharge roller 212 may be further deteriorated in consistency due to the vortex (turbulent flow) of the air flow by the upper fan 131 and the lower fan 132. Problems also arise.

  Furthermore, the upper fan 131 generates airflow from the inside of the apparatus to the paper discharge tray 291 and the lower fan 132 circulates from the paper discharge tray 291 to the inside of the apparatus, and circulates outside and inside the apparatus. For this reason, the heat generated by the fixing device inside the apparatus is circulated between the outside and inside of the apparatus, which may increase the temperature inside the apparatus.

  The present invention has been made in view of the above-described conventional problems, and an image forming apparatus capable of improving stacking performance of discharged sheets on a discharge tray and suppressing an increase in temperature inside the apparatus. It is intended to provide.

  The configuration of the image forming apparatus according to the present invention for solving the above problems is as follows.

  The present invention provides a fixing device that fixes a toner image transferred onto a recording medium to the recording medium, a paper discharge unit that discharges the recording medium after the toner image is fixed and image formation is completed, and the recording medium includes: A discharge tray to be discharged, an upper fan and a lower fan that are provided above and below the discharge means and generate an air flow on the discharge tray, and a rotation control that controls the rotation of the upper fan and the lower fan In the image forming apparatus, the rotation control unit has a function of controlling the rotation of the upper fan and the lower fan according to the position of the recording medium discharged onto the discharge tray. It is characterized by.

  In the invention, it is preferable that the rotation control unit has a function of rotating the lower fan so that the lower fan blows toward the discharge tray when the discharge unit is discharging the recording medium.

  Further, in the present invention, as the rotation control means, when the paper discharge means finishes discharging the recording medium, the rotation of the lower fan is stopped and the upper fan is blown toward the paper discharge tray. It is preferable to have a function of rotating the

  In the invention, it is preferable that the rotation control unit has a function of changing the rotation speeds of the upper fan and the lower fan in accordance with the thickness of the recording medium.

  In the invention, it is preferable that the rotation control unit has a function of changing the rotation speeds of the upper fan and the lower fan in accordance with the size of the recording medium.

  In the invention, it is preferable that the rotation control unit has a function of changing the rotation speeds of the upper fan and the lower fan in accordance with a recording medium conveyance speed discharged from the paper discharge unit.

  In the present invention, it is preferable that the upper fan and the lower fan are provided at positions facing a substantially central portion in the recording medium width direction orthogonal to the recording medium discharge direction of the recording medium to be discharged.

  In the present invention, it is preferable that the lower fan is provided so as to blow air substantially in parallel along the recording medium discharge direction.

  In the present invention, it is preferable that the upper fan is provided so as to blow air toward the outlet side of the paper discharge means.

  In the present invention, it is preferable that the lower fan is provided in the vicinity of the fixing device disposed adjacent to the paper discharge means.

  In the present invention, it is preferable that the upper fan and the lower fan are arranged so as to exhaust heat of the fixing device to the outside of the image forming apparatus.

  According to the present invention, a fixing device that fixes a toner image transferred onto a recording medium to the recording medium, a paper discharge unit that discharges the recording medium after the toner image is fixed and image formation is completed, and the recording A paper discharge tray for discharging the medium, an upper fan and a lower fan that are provided above and below the paper discharge means and generate airflow on the paper discharge tray, and controls rotation of the upper fan and the lower fan. In the image forming apparatus provided with a rotation control unit, the rotation control unit has a function of controlling the rotation of the upper fan and the lower fan according to the position of the recording medium discharged onto the discharge tray. By providing the recording medium, the operation of the upper fan and the lower fan is switched until the recording medium is discharged from the discharge means or after the discharge, thereby changing the discharge posture of the recording medium. By constant, it is possible to improve the stacking of on the paper discharge tray of the recording medium.

  Further, according to the present invention, the rotation control unit includes a function of rotating the lower fan so that the lower fan blows toward the discharge tray when the discharge unit is discharging the recording medium. When the recording medium is discharged, the lower fan can be turned to lift the leading end of the recording medium with the wind force, so that the stacking property can be improved so as not to curl downward.

  Further, according to the present invention, as the rotation control means, when the paper discharge means finishes discharging the recording medium, the rotation of the lower fan is stopped and the upper fan is blown toward the paper discharge tray. The function of rotating the recording medium so that the trailing edge of the recording medium passes through the paper discharge roller is detected by a detecting means such as a photo sensor signal by an actuator, the lower fan is stopped, and the upper fan is operated. The stacking property can be improved by dropping the trailing edge of the recording medium with the wind force so that the trailing edge of the recording medium does not remain on the side wall of the paper discharge tray.

  Further, according to the present invention, the rotation control means has a function of changing the rotational speeds of the upper fan and the lower fan according to the thickness of the recording medium, for example, the thickness of the recording medium is thick. In this case, since it is heavier than that of thin paper, the leading edge of the recording medium is lifted by increasing the blowing amount (rotation speed) of the lower fan, and the blowing amount of the upper fan in consideration of the weight of the recording medium. By reducing the size, the consistency of the recording medium can be improved.

  Further, according to the present invention, the rotation control means includes a function of changing the rotation speeds of the upper fan and the lower fan according to the size of the recording medium, for example, when the recording medium is large Since it is heavier than thin paper, the air blow rate (rotational speed) of the lower fan is increased to raise the tip of the recording medium, and the air flow rate of the upper fan is reduced in consideration of the weight of the recording medium. Thus, the consistency of the recording medium can be improved.

  According to the present invention, the rotation control unit includes a function of changing the rotational speeds of the upper fan and the lower fan according to the recording medium conveyance speed discharged from the paper discharge unit, for example, When multiple paper discharge speeds are set in the image forming apparatus, if the paper discharge speed is high, the leading edge of the recording medium is less likely to curl. By making the amount less, the consistency of the recording medium can be improved.

  According to the present invention, the upper fan and the lower fan are provided at a position facing a substantially central portion in the recording medium width direction orthogonal to the recording medium discharge direction of the recording medium to be discharged. It is possible to effectively improve the consistency of the recording medium by blowing toward the center of the recording medium rather than blowing toward the end of the recording medium.

  Further, according to the present invention, the lower fan is provided so as to blow air substantially in parallel with the recording medium discharge direction, so that the leading end of the recording medium is lifted by the wind force so as not to cause downward curling. Can be improved.

  Further, according to the present invention, the wall facing the rear end of the recording medium is provided by lowering the rear end of the recording medium by providing the upper fan so as to blow toward the outlet side of the paper discharge means. The trailing edge of the recording medium is not caught on the part, and the paper alignment can be improved.

  Further, according to the present invention, the lower fan is provided in the vicinity of the fixing device arranged adjacent to the paper discharge means, thereby preventing a temperature rise in the device due to heat generated by the fixing device. Can do.

  According to the present invention, the upper fan and the lower fan are arranged so as to exhaust the heat of the fixing device to the outside of the image forming apparatus, so that the lower fan and the upper fan generate the fixing device. It is possible to prevent the temperature in the apparatus from rising due to the heat generated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing the overall configuration of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a part of the electrical configuration of the image forming apparatus.

  In the present embodiment, as shown in FIG. 1, a fixing unit (fixing device) 7 that fixes a toner image transferred onto a sheet (recording medium) P to the sheet P, and the toner image is fixed and image formation is completed. A paper discharge roller (paper discharge means) 12b for discharging the discharged paper P, a paper discharge tray 91 for discharging the paper P, and an air flow on the paper discharge tray 91 provided above and below the paper discharge roller 12b are generated. In the image forming apparatus 100, which includes an upper fan 31 and a lower fan 32, and a rotation control means 300 for controlling the rotation of the upper fan 31 and the lower fan 32, as shown in FIG. In addition, a function of controlling the rotation of the upper fan 31 and the lower fan 32 according to the position of the paper P discharged onto the paper discharge tray 91 is provided.

First, the overall configuration of the image forming apparatus 100 according to the present embodiment will be described.
As shown in FIG. 1, the image forming apparatus 100 forms multicolor and single color images on a predetermined sheet (for example, recording sheet) in accordance with image data transmitted from the outside. 110 and an automatic document processing apparatus 120.

  The apparatus main body 110 includes an exposure unit 1, a developing device 2, a photosensitive drum 3, a cleaner unit 4, a charger 5, a transfer unit 6, a fixing unit 7, a paper feed cassette 81, a paper discharge tray 91, and the like. ing.

  A platen glass (original platen) 92 made of transparent glass on which an original is placed is provided above the image reading unit 90 provided on the upper part of the apparatus main body 110, and an automatic original is provided above the platen glass 92. A processing device 120 is attached.

The automatic document processing device 120 automatically conveys the document on the platen glass 92.
Further, the automatic document processing device 120 is configured to be rotatable in the direction of arrow M, and the document can be placed manually by opening the platen glass 92.

Image data handled in the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y).
Accordingly, four developing devices 2, photosensitive drums 3, chargers 5, and cleaner units 4 are provided to form four types of latent images corresponding to the respective colors. Black, cyan, magenta, and yellow are respectively provided. These are set to form four image stations.

  The exposure unit 1 exposes the charged photosensitive drum 3 in accordance with image data input from the outside or image data obtained by reading from a document, thereby generating an electrostatic latent image corresponding to the image data on the photosensitive body. This is an image writing device formed on the surface of the drum 3, and is configured as an LSU (laser scanning unit) provided with a laser emitting portion, a reflection mirror, and the like. The exposure unit 1 is also provided with a polygon mirror that scans the laser beam and optical elements such as a lens and a mirror for guiding the laser beam reflected by the polygon mirror to the photosensitive drum 3.

  Further, as the exposure unit 1, in addition to the above-described configuration, for example, a method using an EL or LED writing head in which light emitting elements are arranged in an array can be employed.

  The exposure unit 1 thus configured forms an electrostatic latent image on the surface of the photosensitive drum 3 by exposing the charged photosensitive drum 3 according to the input image data. It has the function to do.

  The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toners of four colors (Y, M, C, K).

  The photosensitive drum 3 has a cylindrical shape, is disposed above the exposure unit 1, the surface thereof is cleaned by the cleaner unit 4, and the cleaned surface is uniformly charged by the charger 5.

  The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to a charger type as shown in FIG. 1, a contact type roller type or brush type charger is used. It may be used.

  The transfer unit 6 disposed above the photosensitive drum 3 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt driven roller 63, an intermediate transfer roller 64, and an intermediate transfer belt cleaning unit 65. Yes. Four intermediate transfer rollers 64 are provided corresponding to each color of Y, M, C, and K.

  The intermediate transfer belt driving roller 62, the intermediate transfer belt driven roller 63, and the intermediate transfer roller 64 are configured to stretch and drive the intermediate transfer belt 61.

  The intermediate transfer belt 61 is formed in an endless shape using a film having a thickness of about 100 μm to 150 μm, and is provided so as to contact each photosensitive drum 3. A function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 61 by sequentially superimposing and transferring the toner images of the respective colors formed on the photosensitive drum 3 onto the intermediate transfer belt 61. have.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 61 is performed by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61.

  Each intermediate transfer roller 64 applies a transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 61 with respect to the intermediate transfer belt 61. Specifically, a high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 64 in order to transfer the toner image.

  The intermediate transfer roller 64 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61. In this embodiment, the roller-shaped intermediate transfer roller 64 is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the toner images visualized according to the hues on the photosensitive drums 3 are stacked on the intermediate transfer belt 61. The stacked toner images as image information are transported together with the intermediate transfer belt 61, moved to a contact position (secondary transfer position, predetermined position) between the transported paper and the intermediate transfer belt 61, and moved to this contact position. The image is transferred onto the paper by the arranged transfer roller 10.

  At this time, the intermediate transfer belt 61 and the transfer roller 10 are pressed against each other at a predetermined nip, and a secondary transfer bias is applied to the transfer roller 10 to transfer the toner image onto the sheet. The secondary transfer bias is a high voltage having a polarity (+) opposite to the charging polarity (−) of the toner.

  Further, in order to constantly obtain the predetermined nip, the transfer roller 10 that is pressed against the intermediate transfer belt 61 at the secondary transfer position or the intermediate transfer belt drive roller that is pressed against the back side of the intermediate transfer belt 61 at the secondary transfer position. Any one of 62 is made of a hard material (metal or the like), and the other is made of a soft material such as an elastic roller (elastic rubber roller or foaming resin roller or the like).

  In the transfer process described above, the toner adhering to the intermediate transfer belt 61 by coming into contact with the photosensitive drum 3 or the toner remaining on the intermediate transfer belt 61 without being transferred onto the paper by the transfer roller 10 is used in the next process. The intermediate transfer belt cleaning unit 65 is configured to remove and collect the toner image to cause a toner color mixture.

  The intermediate transfer belt cleaning unit 65 is provided on the downstream side of the transfer roller 10 and upstream of the photosensitive drum 3 in the intermediate transfer belt conveyance direction on the path along which the intermediate transfer belt 61 is conveyed.

  The intermediate transfer belt cleaning unit 65 includes a cleaning blade 65 a as a cleaning member that contacts the intermediate transfer belt 61 and cleans the surface of the intermediate transfer belt 61. The intermediate transfer belt 61 in contact with the cleaning blade 65a is supported by an intermediate transfer belt driven roller 63 from the back side.

The paper feed cassette 81 is a tray for storing sheets used for image formation, and is provided below the exposure unit 1 of the apparatus main body 110. Further, a manual paper feed cassette 82 capable of supplying paper from the outside is provided on the outer side of the apparatus main body 110.
A plurality of sheets used for image formation can be stacked on the manual sheet feeding cassette 82. A paper discharge tray 91 for stacking printed sheets face down is provided above the apparatus main body 110.

  Further, the apparatus main body 110 has a substantially vertical sheet conveyance path S for sending the sheets of the sheet feeding cassette 81 and the manual sheet feeding cassette 82 to the sheet discharge tray 91 via the transfer roller 10 and the fixing unit 7. Is provided. In the vicinity of the paper transport path S from the paper feed cassette 81 to the manual paper feed cassette 82 to the paper discharge tray 91, pickup rollers 11a and 11b, a plurality of transport rollers 12a to 12d, a registration roller 13, a transfer roller 10, and a fixing roller. Unit 7 etc. are arranged.

  The transport rollers 12 a to 12 d are small rollers for promoting and assisting the transport of paper, and are provided along the paper transport path S. The transport roller 12b functions as a paper discharge roller that discharges the paper to the paper discharge tray 91, and is therefore referred to as a paper discharge roller.

The pickup roller 11 a is provided near the end of the paper feed cassette 81, picks up paper one by one from the paper feed cassette 81, and supplies it to the paper transport path S.
The pickup roller 11 b is provided near the end of the manual paper feed cassette 82, picks up paper one by one from the manual paper feed cassette 82, and supplies it to the paper transport path S.

  The registration roller 13 temporarily holds the paper conveyed through the paper conveyance path S. The sheet has a function of conveying the sheet to the transfer roller 10 at the timing when the leading edge of the toner image on the photosensitive drum 3 is aligned with the leading edge of the sheet. That is, the registration roller 13 aligns the toner image on the intermediate transfer belt 61 to a predetermined position on the conveyed paper.

  The fixing unit 7 includes a pair of a heat roller 71 and a pressure roller 72 as the fixing roller 70, and the heat roller 71 and the pressure roller 72 are rotated and conveyed with a sheet interposed therebetween.

  The heat roller 71 and the pressure roller 72 are disposed to face each other, and a fixing nip portion is formed at a pressure contact portion between the heat roller 71 and the pressure roller 72.

  The temperature of the heat roller 71 is controlled by a control unit (not shown) so as to reach a predetermined fixing temperature. The controller controls the temperature of the heat roller 71 based on a detection signal from a temperature detector (non-contact type thermistor) (not shown) that detects the temperature of the heat roller 71 provided around the heat roller 71. It controls so that it may become the range of 200 degreeC.

  Further, the heat roller 71 has a function of fusing, mixing, and pressing the multicolor toner image transferred to the paper and thermally fixing the paper with the pressure roller 72 by thermally pressing the toner onto the paper. ing. As shown in FIG. 1, the heat roller 71 is provided with an external fixing belt 73 for fixing the heat roller 71 from the outside.

  On the other hand, similarly to the heat roller 71, the pressure roller 72 is also configured by providing an elastic layer on the peripheral surface of a cylindrical metal core. And it contacts with the heat roller 71 with a predetermined pressure.

  Next, the configuration of the upper fan 31 and the lower fan 32 in the image forming apparatus 100 of the present embodiment will be described.

  As shown in FIG. 1, the upper fan 31 is disposed above the paper discharge roller 12b and is provided to blow toward the paper discharge tray 91, that is, toward the outlet of the paper discharge roller 12b.

  The lower fan 32 is disposed in the vicinity of the fixing unit 7 disposed adjacent to the paper discharge roller 12b below the paper discharge roller 12b, and is directed toward the paper discharge tray 91, that is, a paper discharge direction by the paper discharge roller 12b. Are provided so as to blow air substantially in parallel.

  The upper fan 31 and the lower fan 32 are provided at positions facing substantially the center in the paper width direction orthogonal to the paper discharge direction of the paper P by the paper discharge roller 12b.

  The upper fan 31 and the lower fan 32 are controlled so as to blow air from the inside of the apparatus toward the outside. That is, the heat of the fixing unit 7 is exhausted to the outside of the apparatus.

Next, operation control of the upper fan 31 and the lower fan 32 in the image forming apparatus 100 of the present embodiment will be described with reference to the drawings.
FIG. 3 is an explanatory view showing a state in which the lower fan blows toward the paper discharge tray while the paper is being discharged in the image forming apparatus according to the present embodiment. FIG. It is explanatory drawing which shows the state which ventilates an upper fan toward a paper discharge exit direction.

  As shown in FIG. 2, the upper fan 31 and the lower fan 32 mounted on the image forming apparatus 100 of the present embodiment are connected to the rotation control unit 300 and are controlled for operation by the rotation control unit 300. In the rotation control means 300, an operation process is performed by the CPU 310 based on the operation process of the upper fan 31 and the lower fan 32 that are instructed to be input by the operation unit 320.

  The rotation control unit 300 has a function of rotating the lower fan 32 to blow air toward the paper discharge tray 91 when the paper discharge roller 12b is discharging the paper P.

  With this function, for example, as shown in FIG. 3, the lower fan 32 is operated while the paper P is being discharged, and the paper leading edge P1 is lifted by the wind force so as not to be curled downward to improve stacking performance. be able to.

  Further, the rotation control unit 300 has a function of stopping the rotation of the lower fan 32 and rotating the upper fan 31 to blow the air toward the discharge tray 91 when the discharge roller 12b has finished discharging the paper P. ing.

  With this function, for example, as shown in FIG. 4, at the moment when the paper trailing edge P2 passes the paper discharge roller 12b, detection is performed by a detection means such as a photosensor signal by an actuator (not shown), and the lower fan 32 is stopped. The stacking property can be improved by operating the upper fan 31 and dropping the sheet trailing edge P2 downward by the wind force so that the sheet trailing edge P2 does not remain on the side wall 91a of the sheet discharge tray 91.

  Further, the rotation control unit 300 has a function of changing the rotation speeds of the upper fan 31 and the lower fan 32 in accordance with the thickness of the paper P.

  With this function, for example, when the thickness of the paper P is thicker, it becomes heavier than that of the thin paper. Therefore, as shown in FIG. As shown in FIG. 4, the consistency of the paper P can be improved by controlling the operation so as to reduce the air blowing amount of the upper fan 31 in consideration of the weight of the paper P.

  Further, the rotation control unit 300 has a function of changing the rotation speeds of the upper fan 31 and the lower fan 32 in accordance with the size of the paper P.

  With this function, for example, when the paper P is large, it becomes heavier than when the paper is thin. Therefore, as shown in FIG. As shown in FIG. 4, the consistency of the paper P can be improved by controlling the operation so that the amount of air blown from the upper fan 31 is reduced in consideration of the weight of the paper P.

  The rotation control unit 300 has a function of changing the rotational speeds of the upper fan 31 and the lower fan 32 in accordance with the sheet conveyance speed discharged from the discharge roller 12b.

  With this function, for example, when a plurality of paper discharge speeds are set in the image forming apparatus 100, if the paper discharge speed is high, the paper leading edge P1 is less likely to curl, so the lower fan is lower than when the paper discharge speed is low. By controlling the operation so as to reduce the amount of air blown (number of rotations) 32, the consistency of the paper P can be improved.

  Next, the operation when the paper P is discharged by the upper fan 31 and the lower fan 32 of the image forming apparatus 100 of the present embodiment will be described with reference to the drawings.

  In the image forming apparatus 100, when the paper P is discharged to the paper discharge tray 91, the lower fan 32 is blown toward the paper discharge tray 91 while the paper P is being discharged, as shown in FIG. The consistency of P is improved.

  That is, the lower end of the paper 32 is lifted so that the leading edge P <b> 1 of the paper being discharged does not hang down on the paper discharge tray 91 due to the blowing of the lower fan 32. Thereby, when the paper P is discharged onto the paper discharge tray 91, it is possible to prevent the paper alignment from being disturbed by pressing the paper that has been discharged first by the paper leading edge P1.

  When the trailing edge P2 of the paper is discharged from the paper discharge roller 12b, as shown in FIG. 4, the upper fan 31 blows air toward the paper discharge outlet of the paper discharge roller 12b, thereby matching the paper P. Have good.

  That is, the rear end P2 of the discharged paper is pushed downward by the blow of the upper fan 31. Thereby, when the paper P falls on the paper discharge tray 91, it is possible to prevent the alignment of the paper P from being disturbed by the paper rear end P2 coming into contact with the side wall 91a.

  When the paper trailing edge P2 is discharged from the paper discharge roller 12b, the lower fan 32 is stopped and the upper fan 31 is rotated to blow air. Note that an actuator (lever) and a photo sensor (not shown) are provided in the vicinity of the paper discharge roller 12b as means for detecting that the paper rear end P2 has been discharged from the paper discharge roller 12b.

  The photosensor for detecting the paper P is turned off when the rear end P2 of the paper passes through the actuator, and the photosensor is turned on to push the actuator while the paper P is being discharged.

  The ON / OFF switching timing and operation time of each of the upper fan 31 and the lower fan 32 are determined by actuators and sensors installed at a plurality of locations in the paper transport path S, in addition to the actuator and photosensor in the vicinity of the paper discharge roller described above. It may be after a predetermined time (time determined by the paper discharge speed and the distance between the actuator and the paper discharge roller) has elapsed since the sensor was turned on. That is, it is only necessary to switch when the trailing edge P2 of the sheet is discharged from the discharge roller 12b even a little.

  With the above configuration, according to the present embodiment, the image forming apparatus 100 includes the upper fan 31 and the lower fan 32 that generate airflow on the paper discharge tray 91 on the upper and lower portions of the paper discharge roller 12b. The rotation control means 300 for controlling the operation of the upper fan 31 and the lower fan 32 controls the rotation of the upper fan 31 and the lower fan 32 according to the position of the paper P discharged onto the paper discharge tray 91. Therefore, the paper P is discharged by switching the operation of the upper fan 31 and the lower fan 32 until the paper P is discharged from the paper discharge roller 12b or after being discharged from the paper discharge roller 12b. The posture can be stabilized and the stacking property of the paper P on the paper discharge tray 91 can be improved.

  Further, according to the present embodiment, since the upper fan 31 and the lower fan 32 are controlled to generate an air flow from the inside of the apparatus toward the external paper discharge tray 91, the heat generated in the fixing unit 7 is controlled. Can be exhausted outside to prevent the temperature inside the apparatus from rising. In particular, since the lower fan 32 is provided in the vicinity of the fixing unit 7, it is effective for preventing a temperature rise.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. Embodiments obtained by appropriately combining the disclosed technical means are also included in the technical scope of the present invention.

  For example, in the above-described embodiment, the present invention is applied to a color image forming apparatus (multifunction machine, printer, etc.). However, as long as the printed sheet is discharged to a discharge tray or the like outside the apparatus. The present invention can also be applied to other image forming apparatuses such as monochrome image forming apparatuses.

1 is an explanatory diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a part of an electrical configuration of the image forming apparatus. FIG. 4 is an explanatory diagram illustrating a state in which the lower fan blows air toward the paper discharge tray while the paper is being discharged from the paper discharge roller in the image forming apparatus. FIG. 6 is an explanatory diagram illustrating a state in which the upper fan blows toward the discharge outlet when the rear end of the sheet is discharged from the discharge roller in the image forming apparatus. FIG. 10 is an explanatory diagram illustrating a state of a sheet when a leading end of the sheet is discharged from a discharge roller in a conventional image forming apparatus. FIG. 10 is an explanatory diagram illustrating a state of a sheet when a rear end of the sheet is discharged from a discharge roller in a conventional image forming apparatus.

Explanation of symbols

7 Fixing unit (fixing device)
12b Paper discharge roller (paper discharge means)
31 Upper Fan 32 Lower Fan 91 Paper Discharge Tray 91a Side Wall 100 Image Forming Apparatus 300 Rotation Control Unit 310 CPU
320 Operation section P Paper P1 Paper leading edge P2 Paper trailing edge

Claims (11)

A fixing device that fixes the toner image transferred onto the recording medium to the recording medium; a paper discharge unit that discharges the recording medium after the toner image is fixed and image formation is completed; and a discharge device that discharges the recording medium. A paper tray; an upper fan and a lower fan that are provided above and below the paper discharge means and generate airflow on the paper discharge tray; and a rotation control means that controls the rotation of the upper fan and the lower fan. In the image forming apparatus,
The image forming apparatus according to claim 1, wherein the rotation control unit has a function of controlling rotation of the upper fan and the lower fan in accordance with a position of the recording medium discharged onto the paper discharge tray.   2. The rotation control unit includes a function of rotating the lower fan so as to blow air toward the sheet discharge tray when the sheet discharge unit is discharging the recording medium. Image forming apparatus.   The rotation control unit has a function of stopping rotation of the lower fan and rotating the upper fan to blow air toward the discharge tray when the discharge unit finishes discharging the recording medium. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The said rotation control means is provided with the function to change the rotation speed of the said upper fan and the said lower fan according to the thickness of the said recording medium, The Claim 1 characterized by the above-mentioned. Image forming apparatus.   5. The rotation control unit according to claim 1, wherein the rotation control unit has a function of changing rotation speeds of the upper fan and the lower fan in accordance with a size of the recording medium. Image forming apparatus.   6. The rotation control means comprises a function of changing the rotation speed of the upper fan and the lower fan in accordance with a recording medium conveyance speed discharged from the paper discharge means. The image forming apparatus according to any one of the above.   7. The upper fan and the lower fan are provided at positions facing a substantially central portion in a recording medium width direction orthogonal to a recording medium discharge direction of the recording medium to be discharged. The image forming apparatus according to any one of the above.   The image forming apparatus according to claim 1, wherein the lower fan is provided so as to blow air substantially in parallel along a recording medium discharge direction.   The image forming apparatus according to claim 1, wherein the upper fan is provided so as to blow air toward an outlet side of the paper discharge unit.   The image forming apparatus according to claim 1, wherein the lower fan is provided in the vicinity of the fixing device disposed adjacent to the paper discharge unit.   The image forming apparatus according to claim 1, wherein the upper fan and the lower fan exhaust heat of the fixing device to the outside of the image forming apparatus.

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