JP4630698B2 - Sheet discharging apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet discharge apparatus that discharges an image-processed sheet to a discharge unit and an image forming apparatus including the sheet discharge apparatus, and more particularly to a sheet discharge apparatus that can cool a discharged sheet and an image forming apparatus including the sheet discharge apparatus. .

  In general, an electrophotographic image forming apparatus such as a copying machine or a printer transfers a toner image to a sheet in an image forming unit and heats the sheet in a fixing unit to thermally fix the toner image. Therefore, the sheet that is fixed and discharged to the discharge unit is heated, and heat may be stored when a plurality of sheets are stacked and discharged.

  Therefore, as shown in FIG. 6, there is a sheet in which toner is fixed and cooled to a high temperature by blowing air to the discharged sheet (Patent Document 1).

  The apparatus shown in FIG. 6 has a configuration in which air from the fan 50 is applied to the sheet S being discharged as indicated by an arrow A as means for cooling the sheet S. Accordingly, the sheet can be cooled, and a phenomenon in which a plastic film such as an OHT sheet sticks to each other at the discharge unit 51 due to a high temperature, and an increase in the temperature of the discharge unit 51 can be prevented.

JP2003-208043

  However, in recent years, the printing speed of image forming apparatuses has been increasing. Therefore, the sheet S cannot be sufficiently cooled only by cooling the sheet S being discharged, and there is a possibility that a plastic film such as an OHT sheet sticks to each other at the discharge unit 51 in a high speed machine.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a sheet discharge device capable of effectively cooling a discharge sheet even with a high-speed machine, and an image forming apparatus including the sheet discharge device. Is.

A typical means in the present invention for solving the above-described problems is a sheet discharging apparatus that discharges an image-formed sheet to a discharge unit by a discharge unit, and a blowing unit capable of blowing air to the sheet discharged to the discharge unit. A rotation member having a rotation center at an upper portion of the air blowing port of the air blowing means, and a rotation member that is pushed by the sheet discharged by the discharge means and rotates upward to change the direction of air blown by the air blowing means. comprises, sheets when being discharged to the discharge portion is blown toward the lower surface of the sheet being discharged by said discharge means from said blowing port, the sheet is not discharged to the discharge unit by the discharging means time and changes the so that wind is blown toward the upper surface of the sheet discharged to the discharge unit by the rotation member.

  According to the present invention, it is possible to effectively cool both sides of the sheet discharged to the discharge unit by changing the wind direction when the sheet is discharged and when the sheet is not discharged. Therefore, even in an image forming apparatus with a high printing speed, it is possible to prevent sticking of a plastic film such as an OHT sheet in the discharge section, and further, it is possible to prevent the temperature inside the image forming apparatus from being increased. It is possible to form a good image.

  Next, an image forming apparatus provided with a sheet discharging apparatus according to an embodiment of the present invention will be specifically described.

[First Embodiment]
{Overall configuration of image forming apparatus including sheet discharging apparatus}
First, the overall configuration of the image forming apparatus according to the first embodiment will be described with reference to FIG.

  The image forming apparatus according to the present embodiment uses a recording material such as a recording sheet, an OHT sheet, or the like by an electrophotographic method in accordance with an image information signal from an external host device such as a personal computer that is communicably connected to the apparatus body ( This is a full-color laser beam printer that can form a full-color image on a sheet).

An image forming apparatus 100 shown in FIG. 5 includes four drum-shaped image carriers arranged in a substantially vertical direction, that is, photosensitive drums 1 (1a, 1b, 1c, 1d) as image carriers. ing. The photosensitive drum 1 is driven to rotate counterclockwise in FIG. 5 by a driving unit (not shown). A photosensitive device 2 (2a, 2b, 2c, 2d) that uniformly charges the surface of the photosensitive drum 1 in order according to the rotation direction, and a laser beam is irradiated around the photosensitive drum 1 based on image information. A scanner unit 3 (3a, 3b, 3c, 3d) that forms an electrostatic latent image on the body drum 1, and a developing device 4 (4a, 3d) that develops a toner image by attaching toner included in the developer to the electrostatic latent image. 4b, 4c, 4d), a transfer roller 5 (5a, 5b, 5c, 5d) for transferring the toner image on the photosensitive drum 1 to the sheet S, and transfer residual toner remaining on the surface of the photosensitive drum 1 after transfer. A cleaning device 6 (6a, 6b, 6c, 6d) to be removed is disposed.
In the present embodiment, four image forming units which are image forming units each including a photosensitive drum 1, a charging device 2, a scanner unit 3, a developing device 4, a cleaning device 6 and the like have different colors (depending on the electrophotographic recording method). Yellow, cyan, magenta, and black).

  The photosensitive drum 1 and the charging device 2, the developing device 4, and the cleaning device 6 as process means acting on the photosensitive drum 1 are integrally formed into a cartridge, and a process cartridge 7 (removable with respect to the apparatus main body 100) ( 7a, 7b, 7c, 7d).

  An electrostatic transfer belt (transfer belt) 9a that circulates as a sheet conveying unit is disposed so as to face and contact all the photosensitive drums 1. The transfer belt 9a is stretched around four rollers, a driving roller 9b, driven rollers 9c and 9d, and a tension roller 9e, and the driving roller 9b is rotationally driven by a driving motor (not shown) as an image carrier driving means. Rotate in the direction of the arrow in FIG.

  In forming an image, the sheet S in the feeding cassette 8a attached to the lower part of the apparatus main body is separated and fed one by one by a feeding roller 8a1, a separation roller pair 8a2, and a registration roller pair 8d, and the sheet S is transferred. The belt 9a is electrostatically attracted and conveyed to each image forming unit. In each image forming unit, each color toner image is sequentially transferred onto the sheet S to form a color image, and the sheet is conveyed to the fixing unit 10.

  The fixing unit 10 fixes a plurality of color toner images transferred to the sheet S, and includes a rotating heating roller 10a and a pressure roller 10b that presses the sheet S and applies heat and pressure to the sheet S. That is, the sheet S to which the toner image on the photosensitive drum 1 is transferred is conveyed by the pair of fixing rollers 10a and 10b and is given heat and pressure when passing through the fixing unit 10. As a result, the toner images of a plurality of colors are fixed on the surface of the sheet S. Then, the sheet S on which the toner image is fixed is discharged to a discharge unit 15 provided at the upper part of the apparatus by discharge roller pairs 13 and 14 serving as a sheet discharge apparatus.

  When performing double-sided recording, the sheet S recorded on one side as described above is switched back to be conveyed to the double-sided conveyance path 18, passed through the oblique feeding roller 19, and vertically down to the U-turn roller 20. In the direction, the sheet is conveyed to the image forming unit by the U-turn roller and the registration roller 8d. Then, after recording on the other side, the toner is fixed by the fixing means 10 and discharged to the discharge portion 15.

{Sheet cooling configuration in sheet discharge device}
In the image forming apparatus according to the present embodiment, the sheet S discharged to the discharge unit is cooled and discharged. Next, a configuration for this will be described with reference to FIGS.

  As shown in FIG. 1, conveyance roller pairs 11 and 12 and discharge roller pairs 13 and 14 are provided in the conveyance direction of the sheet S by the heating roller 10 a and the pressure roller 10 b of the fixing unit 10. A passage 22 for air blown by a blower fan 21 serving as a blower is formed below the discharge unit 15. Air is blown onto the sheet discharged to the discharge unit 15 by the conveying roller pair 11 and 12 and the discharge roller pair 13 and 14 on the lower surface of the sheet shown in FIG. 1, that is, the side to which the toner image is transferred. It is constituted as follows. As a result, the discharged sheet is cooled.

  Further, the air blown from the blower fan 21 flows through the air passage 22 from the blower port 16 located on the downstream side in the sheet discharge direction of the discharge roller pair 13 and 14 to the outside of the apparatus. The air blowing port 16 is provided with a rotating member 17 serving as a changing means for changing the direction of the air blown by the blower fan 21. The rotation member 17 has a rotation center at the upper part of the air blowing port 16 and is configured to be larger than the air blowing port 16.

  The rotating member 17 also functions as a full load detecting means for detecting whether or not the sheet discharged to the discharge unit 15 is in a full load state. When the sheet S is not discharged by the discharge roller pairs 13 and 14, the rotating member 17 is at the home position shown in FIG. Then, when the sheet S is discharged to the discharge unit 15 and the number of discharged sheets exceeds a predetermined value, the rotating member 17 comes into contact with the uppermost surface of the discharged sheet. When the rotating member 17 in contact with the uppermost surface of the discharge sheet rotates by a predetermined angle, it is detected that the sheet discharged to the discharge unit 15 is full.

  When the sheet S is discharged to the sheet discharge port where the rotating member 17 is provided, the rotating member 17 is pushed by the leading end of the sheet S as shown in FIG. Until the rear end passes through the discharge roller pair 13 and 14 and is discharged to the discharge portion 15, it is in a position lifted by the sheet S as shown in FIG.

  Therefore, when the sheet S is being discharged to the discharge portion 15 by the discharge roller pair 13 and 14, the air from the blower fan 21 is indicated by the arrow A on the lower surface of the sheet S from the blower port 16, as shown in FIG. Air is blown in the direction to cool the lower surface (image forming surface) which is one surface side of the sheet S.

  When the trailing edge of the sheet S passes through the discharge roller pair 13 and 14 and is discharged to the discharge unit 15, the rotating member 17 rotates by its own weight, and reaches the position of the home position shown in FIG. It returns to the next position until the sheet S is discharged, and is at the home position. At this time, as shown in FIG. 3, the direction of the air from the air blowing port 16 is changed by the rotating member 17, and the upper surface of the sheet S discharged to the discharging unit 15, that is, the other surface side different from the sheet discharging time. Blow out in the direction indicated by arrow B on (non-image forming surface). As a result, air hits the upper surface of the sheet S discharged to the discharge unit 15 and the upper surface of the sheet S is cooled.

  As described above, the sheet is efficiently cooled by blowing air to different surfaces of the sheet when the sheet is discharged and when the sheet is not discharged. For this reason, even in a high-speed machine having a high image forming speed, both sides of the discharged sheet are effectively cooled, and sticking of a plastic film such as an OHT sheet is prevented.

  Here, the relationship between the rotating member and the air blowing port 16 according to the present embodiment will be described. As shown in FIG. 4 (a), the rotation member 17 reliably switches the direction of the air from the blower port 16 to the upper surface of the sheet S discharged to the discharge unit 15, so In this embodiment, the angle α of the rotating member 17 with respect to the air blowing direction W is set so that the angle α is in the range of 95 ° to 120 °. Here, the air blowing direction of the air blowing port 16 indicated by the start point P of the angle α is the direction of the air blowing port 16 immediately before the air from the air blowing fan 21 is taken out of the image forming apparatus as shown in FIG. Can be set.

  The rotating member 17 rotates when pushed by the discharged sheet S, but does not rotate due to the air blown from the blower fan 21 and is configured to have a weight that maintains the state at the home position. Yes.

  When the angle α between the air blowing port 16 and the rotation member 17 is less than 95 °, only the vicinity of the rear end of the sheet S discharged to the discharge unit 15 can be cooled. If the angle α is greater than 120 °, only the vicinity of the front end of the sheet S discharged to the discharge unit 15 can be cooled. For this reason, it is desirable that the angle α between the air blowing port 16 and the rotating member 17 at the home position is in the range of 95 ° to 120 °.

  Further, in order to cool the sheet S by switching the direction of the air from the air blowing port 16 to the upper surface of the sheet S discharged to the discharge unit 15 reliably, this embodiment is performed as shown by L1 in FIG. In the embodiment, the rotating member 17 is configured to be longer by 5 mm to 20 mm downward than the lower surface of the air blowing port 16 indicated by the start point P of the angle α.

  Here, if the length of L1 is 5 mm or less, the air from the blower port 16 cannot be switched efficiently, and the cooling of the sheet S discharged to the discharge unit 15 is insufficient. Even if it is longer than 20 mm, the effect of cooling the sheet S discharged to the discharge unit 15 does not increase. Therefore, it is desirable that the rotating end portion of the rotating member 17 is configured to be longer than the lower end of the air blowing port 16 in the range of length L1 = 5 mm to 20 mm as in the present embodiment.

  Further, as shown in FIG. 4 (b), the portion for switching the air from the air blowing port 16 and the air blowing port 16 of the rotating member 17 is arranged at the center in the sheet width direction (direction orthogonal to the sheet discharging direction) at the discharge port. To do. Thereby, air is sprayed to the whole width direction with respect to the sheet | seat on a discharge part.

  The width L2 of the rotating member 17 is configured to be longer than the width L3 of the air blowing port 16 in a predetermined range. In this embodiment, the width L3 of the blower port 16 is 90 mm, and the width L2 of the rotating member 17 is 100 mm to 130 mm wider than the blower port width. Here, when the relationship between the width L2 of the rotating member and the width L3 of the blower port 16 is L2−L3 <10 mm, the air from the blower port 16 cannot be switched efficiently and is discharged to the discharge unit 15. The sheet S is not sufficiently cooled. Also, the cooling effect does not increase when the relationship is L2−L3> 40 mm. Therefore, in the present embodiment, it is preferable that the width L2 of the rotating member 17 is 100 mm to 130 mm.

  When the sheet S is continuously discharged, when the sheet S is discharged by the discharge roller pair 13 and 14, the wind from the blower fan 21 is discharged by the discharge roller pair 13 and 14 as shown in FIG. The lower surface of the sprayed sheet S is cooled on the lower surface of the sheet S. On the other hand, until the next sheet S is discharged by the discharge roller pairs 13 and 14 after the sheet is discharged, the direction of the wind from the blower fan 21 is changed by the rotating member 17 as shown in FIG. Switching to the upper surface of the sheet S discharged to 15, the upper surface of the discharged sheet S is cooled.

  Then, when the leading edge of the next sheet S pushes around the rotating member 17, the operation of blowing the air from the blower fan 21 onto the lower surface of the next sheet S and cooling it as shown in FIG. is there. By cooling the lower surface of the discharged sheet S and the upper surface of the discharged sheet S in this way, the heat-fixed sheet S is reliably cooled, and a plastic film such as an OHT sheet is attached to the discharge unit 15. In addition, the temperature inside the image forming apparatus 100 is prevented from rising.

  Further, in this embodiment, the wind direction is changed by the rotating member 17, but since the rotating member 17 also serves as a sheet fullness detecting member of the discharge unit 15, a special member is used to change the wind direction of the blower fan 21. There is no need to provide it, and the number of parts does not increase.

FIG. 3 is a cross-sectional view illustrating when the image forming apparatus according to the embodiment of the invention is discharged. FIG. 6 is a cross-sectional view illustrating the operation of a changing unit for changing the wind direction in the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating a state other than when the image forming apparatus according to the embodiment of the present invention is discharged. FIG. 2 is a cross-sectional and perspective view illustrating a full load detection member of the image forming apparatus according to the embodiment of the present invention. 1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating fixing and discharging portions of a conventional image forming apparatus.

Explanation of symbols

S ... sheet 1 ... photosensitive drum 2 ... charging device 3 ... scanner unit 4 ... developing device 5 ... transfer roller 6 ... cleaning device 7 ... process cartridge 8a ... feed cassette 8a1 ... feed roller 8a2 ... separation roller pair 8d ... registration Roller 9a ... transfer belt 9b ... drive roller 9c, 9d ... driven roller 9e ... tension roller
10… Fixing means
10a ... Heating roller
10b… Pressure roller
11, 12… Conveying roller pair
13, 14… discharge roller pair
15… discharge section
16… Blower
17… Rotating member
18… Double-sided conveyance path
19 ... Skew feeding roller
20… U-turn roller
21… Blower fan
22… passage

Claims (9)

In a sheet discharge device that discharges an image-formed sheet to a discharge portion by discharge means,
Blower means capable of blowing air to the sheet discharged to the discharge section;
A rotating member to change the wind direction, which is blown by the blowing means to the upper air duct has a rotation center, and rotates upward by being pushed by the sheet discharged by the discharging means of said blowing means,
Equipped with a,
Sheet when being discharged to the discharge portion is blown toward the lower surface of the sheet being discharged by said discharge means from said blowing port,
Sheet discharging apparatus characterized by changing the so that wind is blown toward the upper surface of the sheet discharged to the discharge unit by the rotating member when the sheet is not discharged to the discharge unit by the discharging means . The turning end portion of the rotating member, the sheet discharging device according to claim 1, characterized in that it has a length extending up to below the lower end of the blower opening. The sheet discharging apparatus according to claim 2 , wherein a rotating end portion of the rotating member extends from 5 mm to 20 mm below a lower end of the air blowing port. The sheet length of the discharge direction orthogonal to the width direction of the discharge means of the rotating member is any one of claims 1 to 3, characterized in longer than the length in the width direction of the air blowing port 1 The sheet discharging apparatus according to the item. The sheet discharging apparatus according to claim 4 , wherein a length in the width direction of the rotating member is longer than a length in the width direction of the blower opening by a difference of 10 mm or more and 40 mm or less. The rotary member and the blower port sheet discharge apparatus according to any one of claims 1 to 5, characterized in that arranged at the center in the direction orthogonal to the sheet conveying direction in the sheet discharge port . The sheet discharge according to any one of claims 1 to 6 , wherein the rotating member also serves as a full load detection means for detecting that a predetermined amount of sheets have been discharged to the discharge portion. apparatus. An image forming unit for forming an image on a sheet;
An image forming apparatus comprising the sheet discharging device according to any one of claims 1 to 7 for discharging the sheet on which the image is formed. The image forming apparatus according to claim 8, wherein the sheet on which the image is formed by the image forming unit is conveyed to a fixing unit and heat-fixed.

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