JP2012032434A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preferably cooling a paper after fixation.SOLUTION: A paper conveyance switching guide 200 is provided on the downstream side from a fixing device 10 on a conveyance path 114 of a paper P. The paper conveyance switching guide 200 includes a pipe part 210 and a guide part 220. Air blown from a cooling fan 130 flows in the pipe part 210. When the paper P is conveyed to a pair of rollers 118 (passing through the upper side of the paper conveyance switching guide 200), such a state that an upper through-hole 211 of the pipe part 210 and an upper through-hole 221 of the guide part 220 are communicated with each other is made by the paper conveyance switching guide 200. When the paper P is conveyed to a pair of rollers 116 (passing through the lower side of the paper conveyance switching guide 200), such a state that a lower through-hole 212 of the pipe part 210 and a lower through-hole 222 of the guide part 220 are communicated with each other is made by the paper conveyance switching guide 200.

Description

  The present invention relates to an image forming apparatus. More specifically, the present invention relates to an image forming apparatus capable of suitably cooling a sheet after fixing.

  In an image forming apparatus using an electrophotographic system, toner is applied to an electrostatic latent image formed on a photosensitive drum to form a toner image, and the toner image is transferred to a sheet. Then, the toner image is fixed on a sheet by a fixing device.

  In an image forming apparatus that forms an image at high speed, the following problems may occur when images are formed on both sides of a sheet. That is, the toner of the discharged paper and the toner of the paper discharged before that stick together, and the paper sticks to each other. This is considered to occur because the fixed toner is not sufficiently cooled and the sheets overlap while the toner temperature remains high.

  Therefore, techniques for cooling the paper after fixing have been developed. For example, Patent Document 1 discloses an image forming apparatus that can cool sheets placed in two places with a single cooling fan. Thus, the paper placed on each paper discharge tray can be effectively cooled with a small number of cooling fans. Patent Document 2 discloses an image forming apparatus that blows air from a cooling fan toward a switchback conveyance path and a paper discharge tray. As a result, the paper after fixing can be cooled without providing a cooling fan for each paper discharge tray.

JP 2002-72729 A JP 2007-264416 A

  However, in the image forming apparatus described in Patent Document 1, the position where the cooling fan is arranged is fixed. This is disadvantageous for downsizing the image forming apparatus. Similarly, even in the image forming apparatus described in Patent Document 2, the position where the cooling fan is disposed is limited.

  The present invention has been made to solve the above-described problems of the prior art. That is, the problem is to provide an image forming apparatus capable of suitably cooling the sheet after fixing.

  In order to solve this problem, an image forming apparatus according to an aspect of the present invention includes an image forming unit that forms a toner image on an image carrier, a transfer unit that transfers the toner image to a sheet, and at least heating the sheet. A fixing unit that fixes the toner image on the sheet, a first conveyance path and a second conveyance path for conveying the sheet on which the toner image is fixed, and the first conveyance path and the second conveyance path. A sheet conveyance direction change unit that is positioned between the sheet conveyance direction and switches between whether the sheet is conveyed to the first conveyance path or the second conveyance path. The sheet conveying direction changing unit includes a first air hole formed in a direction toward the first conveyance path and a direction directed toward the second conveyance path. A duct portion in which two through-holes are formed and air is blown from the blower portion, and a guide portion that is movable with respect to the duct portion and in which the third and fourth through-holes are formed. A first communication state in which the first through-hole and the third through-hole communicate with each other and the second through-hole and the fourth through-hole do not communicate with each other; And the third through hole and the second through state in which the second through hole and the fourth through hole are in communication with each other, and the sheet is placed in the first conveyance path. When in the state of transporting the sheet, the first communication state is established and the sheet is transported to the second transport path When in the state of, those taking the second communication state. In such an image forming apparatus, air can be blown in accordance with the location where the sheet is conveyed. Thereby, the paper can be suitably cooled.

  In the image forming apparatus described above, the duct portion has a cylindrical shape, the guide portion is rotatable around the outer periphery of the cylindrical shape of the duct portion, and the sheet conveyance direction changing portion is the first communicating portion. Switching between the state and the second communication state may be performed by turning the guide portion. This is because the communication state can be switched smoothly.

  An image forming apparatus according to another aspect of the present invention includes an image forming unit that forms a toner image on an image carrier, a transfer unit that transfers the toner image to a sheet, and a toner image that is heated by at least heating the sheet. The image forming apparatus includes a fixing unit for fixing the sheet, a conveyance path for conveying the sheet on which the toner image is fixed, and a fixed guide for conveying the sheet on which the toner image is fixed to the conveyance path. And it has a ventilation part which ventilates air, and a fixed guide has a duct part by which air is ventilated from the ventilation part while the through-hole is formed in the direction which goes to a conveyance path | route. In such an image forming apparatus, air can be blown from the fixed guide toward the sheet according to the position where the sheet is conveyed. Thereby, the paper can be suitably cooled.

  According to the present invention, an image forming apparatus capable of suitably cooling a sheet after fixing is provided.

1 is a schematic configuration diagram for explaining an image forming apparatus according to an embodiment. FIG. 4 is a diagram for explaining the periphery of the fixing device in the image forming apparatus according to the embodiment. FIG. 4 is a perspective view for explaining a sheet conveyance switching guide of the image forming apparatus according to the embodiment. FIG. 4 is a sectional view (No. 1) showing a BB section in FIG. 3; FIG. 4 is a sectional view (No. 2) showing a BB section in FIG. 3. FIG. 3 is a cross-sectional view for explaining a fixed guide of the image forming apparatus according to the embodiment.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, the present invention is embodied in an electrophotographic image forming apparatus.

1. Image Forming Apparatus The image forming apparatus 1 of the present embodiment is a so-called tandem color printer having an intermediate transfer belt 101 as schematically shown in FIG. The intermediate transfer belt 101 is an endless belt member. Both ends of the intermediate transfer belt 101 are supported by rollers 102 and 103 and rotate in the direction of arrow A in the drawing. Along the lower portion of the intermediate transfer belt 101 in the figure, image forming portions 104Y, 104M, 104C, and 104K for each color of yellow (Y), magenta (M), cyan (C), and black (K) are arranged.

  The image forming units 104Y, 104M, 104C, and 104K for each color have the same configuration. Each includes a photosensitive drum 106 and a charging device 107, an exposure device 108, a developing device 109, and a cleaner device 110 arranged around the photosensitive drum 106. A primary transfer device 111 is disposed at a position facing the photosensitive drum 106 with the intermediate transfer belt 101 interposed therebetween. In FIG. 1, the image forming unit 104Y is representatively shown.

  1 shows a paper feed cassette 112 that stores paper P. A paper feed roller 113 that feeds the paper P is provided above the paper feed cassette 112. The paper P is sent upward from the paper feed cassette 112 along the transport path 114. A secondary transfer device 115 is disposed at a position facing the roller 103 with the conveyance path 114 interposed therebetween. The intermediate transfer belt 101, the primary transfer device 111, and the secondary transfer device 115 are transfer portions. Further, a fixing device 10 is arranged on the downstream side (upper side in the drawing). The fixing device 10 is a fixing unit having a roller pair of a heating roller 11 and a pressure roller 12. A paper conveyance switching guide 200 is disposed further downstream of the conveyance path 114 from the fixing device 10.

  A roller pair 116 and a roller pair 118 are arranged further downstream of the conveyance path 114 from the sheet conveyance switching guide 200. A conveyance path from the fixing device 10 toward the roller pair 116 is a first conveyance path. A transport path from the fixing device 10 toward the roller pair 118 is a second transport path. The paper transport switching guide 200 is located between the first transport path and the second transport path. The paper transport switching guide 200 is for switching between transporting the paper P to the first transport path or the second transport path. A paper discharge tray 117 is provided further downstream of the conveyance path 114 than the roller pair 116. The roller pair 116 is for discharging the paper P to the paper discharge tray 117.

  The roller pair 118 is for reversing the transport direction of the paper P that has been transported along the transport path 114 and for transporting the paper P to the transport path 119. The conveyance path 119 is a path for conveying the paper P on which an image is formed on one side to the location of the secondary transfer device 115 again. In other words, this is a path used to form an image on the opposite side of the sheet P where the image is formed. As described above, the image forming apparatus 1 of the present embodiment is capable of duplex printing.

  In addition, the image forming apparatus 1 has a cooling fan 130. The cooling fan 130 is for blowing air to the pipe 131. As will be described later, the pipe 131 is connected to the sheet conveyance switching guide 200.

  Next, the basic operation of the image forming apparatus 1 of this embodiment will be briefly described. When the image forming apparatus 1 receives an image forming instruction, the image forming apparatus 1 generates image data of each color from the image signal. The generated image data of each color is sent to the corresponding image forming units 104Y, 104M, 104C, and 104K. The image forming units 104Y, 104M, 104C, and 104K for each color form electrostatic latent images by charging and exposing the respective photosensitive drums 106 based on the image data. Further, the formed electrostatic latent image is developed to form a toner image.

  The formed toner images are sequentially transferred to the intermediate transfer belt 101 by the primary transfer device 111 and superimposed. The toner image superimposed on the intermediate transfer belt 101 is transferred onto the paper P by the secondary transfer device 115. The paper P carrying the toner image is further conveyed to the fixing device 10 where it is heated and pressurized by the fixing device 10. As a result, the toner image is fixed on the paper P. The paper P on which the toner image is fixed is discharged to the paper discharge tray 117 by the roller pair 116.

  On the other hand, in the case of duplex printing, the paper P on which the toner image is fixed is conveyed to the conveyance path 119 by the roller pair 118. Then, it is conveyed again to the secondary transfer device 115. At this time, the toner image is transferred to the surface opposite to the surface on which the toner image has already been fixed. Thereafter, the toner image is fixed and discharged onto the paper discharge tray 117. The above is the basic operation of the image forming apparatus 1.

2. Paper Transport Switching Guide The paper transport switching guide 200 is a paper transport direction changing unit for switching the transport direction of the paper P after fixing. As shown in FIG. 2, the sheet conveyance switching guide 200 is rotatable in the direction of arrow C in FIG. For this reason, the sheet conveyance switching guide 200 can take two different states, the position of the solid line in FIG. 2 and the position of the chain double-dashed line.

  When the paper transport switching guide 200 is at the position indicated by the solid line in FIG. 2, the paper P is transported to the position of the roller pair 118. The roller pair 118 is for transporting the paper P to the transport path 119. That is, the roller pair 118 rotates in a reverse direction after rotating by a predetermined number of rotations so that the rear end of the paper P does not pass after the front end of the paper P has entered. That is, the transport direction of the paper P is reversed and the paper P is transported to the transport path 119. As described above, the sheet conveyance switching guide 200 is located at the position indicated by the solid line in FIG. 2 when double-sided printing is performed and the first image is fixed.

  When the sheet conveyance switching guide 200 is at the position indicated by the two-dot chain line in FIG. 2, the sheet P is conveyed to the position of the roller pair 116. The roller pair 116 is for discharging the paper P to the paper discharge tray 117. In this way, the sheet conveyance switching guide 200 is located at the position indicated by the two-dot chain line in FIG. 2 when performing single-sided printing or when performing double-sided printing and fixing the image on the second side.

  FIG. 3 is a perspective view of the paper transport switching guide 200. The paper transport switching guide 200 has a pipe part 210 and a guide part 220. The pipe part 210 is a duct part for blowing air. The connecting part 201 of the pipe part 210 is connected to the pipe 131 (see FIG. 1). Therefore, the air sent from the cooling fan 130 flows into the pipe part 210. Further, the pipe portion 210 exists over the entire width of the paper transport switching guide 200. The end portion (left end in FIG. 3) of the pipe portion 210 is closed. The pipe unit 210 is fixed to the main body of the image forming apparatus 1. The guide unit 220 is for transporting the paper P and changing its transport direction. The guide part 220 is movable with respect to the pipe part 210 as will be described later.

  FIG. 4 is a cross-sectional view showing the BB cross section of FIG. 3 when the paper conveyance switching guide 200 is at the position of the solid line of FIG. As shown in FIG. 4, the pipe part 210 has a cylindrical shape. A cylindrical interior 213 of the pipe part 210 is for blowing air. A cylindrical interior 213 of the pipe part 210 is connected to the pipe 131. That is, the air sent from the cooling fan 130 flows.

  An upper through hole 211 and a lower through hole 212 are formed in the pipe part 210. The upper through hole 211 and the lower through hole 212 are through holes penetrating from the outer peripheral surface of the pipe part 210 to the cylindrical interior 213. A plurality of upper through holes 211 are provided at equal intervals in a line in the axial direction of the pipe part 210. The upper through hole 211 of the pipe part 210 is formed in a direction toward the second transport path. A plurality of lower through holes 212 are provided at equal intervals in a line in the axial direction of the pipe portion 210. The lower through hole 212 of the pipe part 210 is formed in a direction toward the first transport path.

  As shown in FIG. 4, a guide part 220 is disposed just outside the outer peripheral edge of the pipe part 210. The guide part 220 includes a cylindrical part 225, fins 223, and fins 224. The fins 223 are for actually contacting the paper P and determining the transport direction of the paper P. The fins 224 are reinforcing members that connect the fins 223 to each other.

  The cylindrical portion 225 of the guide portion 220 is provided with an upper through hole 221 and a lower through hole 222. The upper through-hole 221 is a through-hole penetrating from the outside to the inside of the cylindrical portion 225. The lower through hole 222 is a through hole penetrating from the outside to the inside of the cylindrical portion 225. A plurality of upper through holes 221 are provided at equal intervals in a line in the axial direction of the pipe part 210. A plurality of lower through holes 222 are provided at equal intervals in a line in the axial direction of the pipe portion 210.

  When the pipe part 210 is cut along a cross section perpendicular to the cylindrical axis (for example, the BB cross section of FIG. 3), the upper through hole 211 of the pipe part 210 and the upper through hole 221 of the guide part 220 are located on the same cross section. (See FIG. 4). As shown in FIG. 4, the upper through hole 211 and the lower through hole 212 of the pipe part 210 are formed at positions almost opposite to each other across the cylindrical center O that is the center of the pipe part 210.

  When the pipe portion 210 is cut along a cross section perpendicular to the cylindrical axis (for example, the BB cross section of FIG. 3), the lower through hole 212 of the pipe portion 210 and the lower through hole 222 of the guide portion 220 are on the same cross section. Located (see FIG. 4). Therefore, in this embodiment, the upper through hole 211 and the lower through hole 212 of the pipe portion 210 and the upper through hole of the guide portion 220 when cut along a cross section perpendicular to the cylindrical axis of the pipe portion 210 (for example, the BB cross section of FIG. The hole 221 and the lower through hole 222 are located on the same cross section.

  The pipe unit 210 is fixed to the image forming apparatus 1. The guide portion 220 can be rotated by a predetermined angle around the cylindrical center O. That is, the guide part 220 can rotate in the direction indicated by the arrow C in FIG. As described above, the guide part 220 rotates along the cylindrical outer surface of the pipe part 210.

  FIG. 4 shows a case where the sheet conveyance switching guide 200 is in the position of the solid line in FIG. In this case, the sheet conveyance switching guide 200 is in the following communication state. That is, the upper through hole 211 of the pipe part 210 and the upper through hole 221 of the guide part 220 communicate with each other. At this time, the upper through hole 211 is open. On the other hand, the lower through hole 212 of the pipe part 210 and the lower through hole 222 of the guide part 220 are not in communication. At this time, the lower through hole 212 is closed by the cylindrical portion 225.

  In the communication state as shown in FIG. 4, the air sent from the cooling fan 130 is discharged in the direction of the arrow D in FIG. That is, it is discharged through the upper through hole 211 of the pipe part 210 that communicates with the upper through hole 221 of the guide part 220. Therefore, the air sent from the cooling fan 130 cools the paper P conveyed from the roller pair 118 to the conveyance path 119. That is, in this communication state, the paper P and the fixing device upper cover 7 are cooled in the switchback process during double-sided printing (see FIGS. 1 and 2).

  FIG. 5 is a cross-sectional view showing the BB cross section of FIG. 3 when the sheet conveyance switching guide 200 is located at the position of the two-dot chain line of FIG. In this case, the sheet conveyance switching guide 200 is in the following communication state. That is, the lower through hole 212 of the pipe part 210 and the lower through hole 222 of the guide part 220 communicate with each other. At this time, the lower through-hole 212 is open. On the other hand, the upper through hole 211 of the pipe part 210 and the upper through hole 221 of the guide part 220 are not in communication. At this time, the upper through hole 211 is closed by the cylindrical portion 225.

  In the communication state as shown in FIG. 5, the air sent from the cooling fan 130 is discharged in the direction of arrow E in FIG. That is, it is discharged through the lower through hole 212 of the pipe part 210 that communicates with the lower through hole 222 of the guide part 220. Therefore, the air sent from the cooling fan 130 cools the paper P conveyed from the fixing device 10 to the roller pair 116. That is, in this communication state, the paper P after completion of single-sided printing and the paper P after completion of double-sided printing are cooled.

  As described above, the image forming apparatus 1 according to the present embodiment ejects air to the upper side of the paper transport switching guide 200 when the paper P passes the upper side of the paper transport switching guide 200. Conversely, when the paper P passes below the paper transport switching guide 200, air is jetted to the lower side of the paper transport switching guide 200. That is, the image forming apparatus 1 has a structure in which air is ejected toward the conveyed paper P side.

  A solenoid can be used to rotate the guide unit 220 of the paper transport switching guide 200. Further, it can be rotated by gear driving using a torque limiter and a spring.

3. Modification In this embodiment, the paper conveyance switching guide 200 for switching the conveyance path is provided with a duct portion for flowing air and a through hole for ejecting air. However, air may be ejected from the fixed guide instead of the switching guide for switching the paper conveyance direction.

  FIG. 6 shows a fixed guide 300 that can blow air onto a sheet. The fixed guide 300 is fixed to the main body of the image forming apparatus. A cylindrical interior 313 of the fixed guide 300 is connected to the pipe 131. That is, the air sent from the cooling fan 130 flows in the direction of arrow F. The cylindrical portion 325 of the fixed guide 300 is provided with fins 323 and fins 324.

  A through hole 322 is formed in the cylindrical portion 325. The through hole 322 is an opening through which air for cooling the paper is ejected. The fixed guide 300 may be provided in an image forming apparatus for single-sided printing. For example, the roller pair 118 and the conveyance path 119 in FIG. 1 are not provided. Further, even an image forming apparatus for double-sided printing can be provided in the middle of a paper conveyance path.

4). Summary As described above in detail, the image forming apparatus 1 according to the present embodiment includes the sheet conveyance switching guide 200 that can eject air. The paper conveyance switching guide 200 blows air upward when the paper P is conveyed on the upper side, and blows air downward when the paper P is conveyed on the lower side. . That is, the paper conveyance switching guide 200 can blow air toward a direction in which the paper P is present. As a result, an image forming apparatus that can suitably cool the paper P on which the toner image is fixed is realized.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the image forming apparatus is not limited to a color printer. That is, it is not limited to color. It is not limited to a printer. It can also be applied to copiers. Further, the present invention can be applied to an image forming apparatus having a function of receiving a print job from a public line and forming an image, and other apparatuses for forming an image. Also, it can be applied regardless of the type of toner. Further, the present invention is not necessarily applied to an image forming apparatus for duplex printing.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 7 ... Fixing apparatus upper cover 10 ... Fixing apparatus 11 ... Heating roller 12 ... Pressure roller 101 ... Intermediate transfer belts 102, 103 ... Rollers 104Y, 104M, 104C, 104K ... Image forming unit 111 ... Primary transfer Device 115 ... Secondary transfer device 114, 119 ... Conveyance path 116, 118 ... Roller pair 117 ... Paper discharge tray 130 ... Cooling fan 131 ... Pipe 200 ... Paper conveyance switching guide 210 ... Pipe section 211 ... Upper through hole 212 ... Lower through hole Hole 213 ... Cylinder inside 220 ... Guide part 221 ... Upper through hole 222 ... Lower through hole 223 ... Fin 224 ... Fin 225 ... Cylindrical part O ... Cylinder center P ... Paper

Claims (3)

An image forming unit for forming a toner image on the image carrier;
A transfer section for transferring a toner image to a sheet;
A fixing unit for fixing the toner image to the sheet by heating at least the sheet;
A first conveyance path and a second conveyance path for conveying the sheet on which the toner image is fixed;
A sheet conveyance direction changing unit that is positioned between the first conveyance path and the second conveyance path and switches between the first conveyance path and the second conveyance path. In an image forming apparatus having
A blower that blows air;
The paper transport direction changing unit is
A first through hole formed in a direction toward the first transport path and a second through hole formed in a direction toward the second transport path are formed, and air is blown from the blower unit. A duct part to be
A guide part movable with respect to the duct part and formed with a third through hole and a fourth through hole;
A first communication state in which the first through-hole and the third through-hole communicate with each other and the second through-hole and the fourth through-hole do not communicate with each other;
The first through hole and the third through hole are not in communication with each other, and the second communication state in which the second through hole and the fourth through hole are in communication is taken. Along with
When the sheet is in a state of being conveyed to the first conveyance path, the first communication state is taken,
2. The image forming apparatus according to claim 1, wherein the second communication state is established when the sheet is conveyed to the second conveyance path. The image forming apparatus according to claim 1,
The duct portion has a cylindrical shape,
The guide portion is rotatable around a cylindrical outer periphery of the duct portion;
The paper transport direction changing unit is
An image forming apparatus characterized in that switching between the first communication state and the second communication state is performed by rotating the guide portion. An image forming unit for forming a toner image on the image carrier;
A transfer section for transferring a toner image to a sheet;
A fixing unit for fixing the toner image to the sheet by heating at least the sheet;
A conveyance path for conveying the sheet on which the toner image is fixed;
An image forming apparatus having a fixed guide for conveying the sheet on which the toner image is fixed to the conveyance path,
A blower that blows air;
The fixed guide is
An image forming apparatus comprising: a through-hole formed in a direction toward the conveyance path; and a duct portion that blows air from the blower portion.

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