JP4530077B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a paper path direction switching unit in a paper conveyance path of an image forming apparatus.

  In general, an electrophotographic image forming apparatus transfers a toner image visualized by toner development onto a sheet, and pressurizes and heats the sheet on which the toner image is transferred to a sheet by a fixing unit. To settle.

  The sheet subjected to the fixing process by the fixing unit is guided to the first sheet conveying path or the second sheet conveying path by a sheet conveying path switching unit that switches the sheet traveling direction.

  The first paper transport path is, for example, a paper transport path for sending the paper to a paper output tray of the image forming apparatus or a downstream processing apparatus connected downstream, and the second paper transport path is, for example, This is a paper transport path for sending the paper to the paper reversing means or sending it to the refeed means for forming an image on the back surface of the paper.

  The paper transport path switching unit is configured to guide the paper to a predetermined paper transport path by moving a paper guide member with which a front end portion of the paper is slidably contacted to regulate a traveling direction of the paper. Many (see, for example, Patent Document 1).

  Such a paper transport path switching unit can be realized with a simple configuration and has a feature of low cost. However, since the paper immediately after the fixing process is strongly contacted and bent by the paper guide member, it is strong against the paper. Stress is applied.

Further, since the image surface of the paper heated by the fixing process is in sliding contact with the paper guide member, the toner and wax on the paper surface adhere to the paper guide member, and the adhered toner and wax adhere to the paper again. May cause problems.
JP 2006-330250 A

  The present invention has been made in view of the above-described situation, and an object of the present invention is to form an image having a paper conveyance path that branches into a first paper conveyance path and a second paper conveyance path downstream of the fixing unit. In the apparatus, an image forming apparatus having an air blowing unit that switches a paper transport path of the paper to the first transport path or the second transport path by blowing air onto the paper.

The above-mentioned subject is achieved by realizing the following invention.
1. An image forming unit that forms a toner image on paper;
A fixing unit for fixing the Paper the toner image,
A paper transport path that branches into a first paper transport path and a second paper transport path downstream of the fixing unit;
By blowing air into the paper, a blowing portion for guiding the sheet to said first sheet transport path or the second paper transport path,
A control unit for controlling the blowing of the blowing unit ,
The image forming apparatus according to claim 1, wherein the control unit performs control to weaken the blowing of the air blowing unit while air is being blown onto the paper .
2. The blowing unit includes a first blowing member for blowing air into the first side of the paper, is arranged opposite to the first blowing member, and the second blowing member for blowing air into the second surface of the sheet, the 2. The image forming apparatus as described in 1 above .
3. Said first blowing member and the second blowing member is an image forming apparatus according to item 2, characterized in that a slit-shaped air outlet.
4). Air blown from the first blower member and the second blowing member, after striking the surface of the sheet conveyed, so as to be directed in the direction of the front end of said sheet, said second blowing member and the first blowing member 4. The image forming apparatus according to 2 or 3, wherein the image forming apparatus is disposed .
5). The blowing unit includes a first air amount changing unit for changing the amount of air blown out from the first blowing member, and a second air amount changing unit for changing the amount of air blown out from the front Stories second blowing member, in that it comprises 5. The image forming apparatus according to any one of 2 to 4, wherein the image forming apparatus is characterized.
6). Said first air amount changing unit and the second air amount changing unit, to the air outlet, the opening area adjusting member for changing the opening area is provided, by moving the opening area adjusting member, said air outlet 6. The image forming apparatus as described in 5 above, wherein the amount of air blown from the air is changed.
7). The blower is characterized in that it comprises a first air valve for turning on and off the balloon of air from the first blowing member, and a second air valve for turning on and off the balloon of air from the second blowing member the image forming apparatus according to any one of the 2 to 6 terms.
8). The controller is
Based on the signal sent from the paper detection sensor for detecting the leading edge of the sheet, to calculate the position information of the tip of paper for Ru is conveyed,
Based on the calculated positional information, the first air valve, and an image forming apparatus according to item 7, wherein the determined Teisu Rukoto the on-off timing of the second air valve.

  In an image forming apparatus having a sheet conveyance path that branches into a first sheet conveyance path and a second sheet conveyance path downstream of the fixing unit, the sheet conveyance path is switched by the sheet guide member according to the present invention. Unlike switching of the paper transport path to be switched, a strong stress due to bending is not applied to the paper immediately after the fixing process, so that the occurrence of curling of the paper is suppressed.

  Further, the image surface of the paper heated by the fixing process does not come into strong sliding contact with the paper guide member and is further cooled by air, so that toner or wax adheres to the paper guide member and reattaches to the paper. Can prevent problems.

  Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to this example.

  FIG. 1 is a conceptual diagram of a conventional color image forming apparatus G.

Color image forming apparatus G illustrated in the figure, arranged in tandem so as to face the plurality of photosensitive bodies 31Y, 31 M, 31 C, 31 K on the intermediate transfer belt 41 of single tandem to form a full color image This is called a color image forming apparatus.

  The color image forming apparatus G includes an automatic document feeder ADF at the top thereof.

  The documents D placed on the document placement table 103 of the automatic document feeder ADF are separated one by one, sent to the document transport path, and transported by the transport drum 108.

  The image of the document D being conveyed is read by the document reading unit 1 at the document image reading position RP. The document D that has been read is discharged to a document discharge table 107 by a plurality of conveyance guides and a document discharge roller 105.

  The image forming apparatus G includes a document reading unit 1, exposure units 2Y, 2M, 2C, and 2K, image forming units 3Y, 3M, 3C, and 3K, an intermediate transfer unit 4, a fixing unit 5, a reverse discharge unit 6, and a refeed. The unit 7, the sheet feeding unit 8, the control unit C, and the like are housed in one housing.

  The document reading unit 1 irradiates the image of the document with the lamp L at the document reading position RP, guides the reflected light by the first mirror unit 11, the second mirror unit 12, and the lens 13, and receives the light receiving surface of the image sensor CCD. To form an image.

  The image signal photoelectrically converted by the image sensor CCD is subjected to processing such as A / D conversion, shading correction, and compression by the image reading control unit 14 and is stored as image data in the memory of the control unit C.

  The image data stored in the memory is subjected to appropriate image processing according to conditions set by the user, and output image data is generated.

  The exposure units 2Y, 2M, 2C, and 2K include a laser light source, a polygon mirror, a plurality of lenses, and the like, and generate a laser beam.

  The exposure units 2Y, 2M, 2C, and 2K are components of the image forming units 3Y, 3M, 3C, and 3K corresponding to the output information output based on the output image data sent from the control unit C. The surfaces of the photoreceptors 31Y, 31M, 31C, and 31K are scanned and exposed with a laser beam.

  By scanning exposure with the laser beam, latent images are formed on the photoconductors 31Y, 31M, 31C, and 31K.

The image forming unit 3Y includes a photoconductor 31Y and a main charging unit 32Y, a developing unit 33Y, a first transfer roller 34Y, and a cleaning unit 35Y arranged around the photoconductor 31Y. The same applies to the image forming units 3M, 3C, and 3K .

  The latent images on the photoconductors 31Y, 31M, 31C, and 31K are developed by the corresponding developing units 33Y, 33M, 33C, and 33K, and toner images are formed on the photoconductors.

  The toner images formed on the photoreceptors 31Y, 31M, 31C, and 31K are placed at predetermined positions on the intermediate transfer belt 41, which is an intermediate transfer body, by the first transfer rollers 34Y, 34M, 34C, and 34K of the intermediate transfer unit 4. Sequentially transferred.

The surface of the photoreceptor after the transfer of the toner image remaining toner is removed by the cleaning unit 35Y, 35 M, 35 C, 35 K.

  On the other hand, the toner image transferred onto the intermediate transfer belt 41 is conveyed from the trays PG1, PG2, and PG3 of the paper feeding unit 8 by the second transfer roller 42, and is sent out at a timing by the paper feeding roller 81. Is transferred onto the printed paper P.

  After the transfer of the toner image onto the paper P, the intermediate transfer belt 41 is cleaned by the belt cleaning unit 43 and used for the next image transfer.

  On the other hand, the paper P carrying the toner image is sent to the fixing unit 5 and is heated under pressure to fix the toner image on the paper P.

  The sheet P that has been subjected to the fixing process by the fixing unit 5 is guided by the sheet conveyance path switching unit 6 and discharged onto the sheet discharge tray 61.

  When the paper P is reversed and discharged, the paper P is once guided downward by the paper discharge guide 62, the rear end of the paper P is sandwiched between the paper discharge reverse rollers 63, and then the paper P is reversed. The sheet is guided to the sheet discharge roller 64 by the sheet discharge guide 62 and discharged.

  When image formation is performed also on the back surface of the paper P, the paper P on which the image fixing on the front surface has been completed is conveyed by the paper guide member 62 to the refeeding section 7 below, and by the refeeding reverse roller 71. After pinching the rear end, the paper P is reversed by reverse feeding and sent to the refeed conveyance path 72 for image formation on the back surface.

  FIG. 2 is a conceptual diagram of an image forming apparatus G1 according to the present invention.

  The image forming apparatus G1 is different from the above-described color image forming apparatus G in the configuration of the sheet conveyance path switching unit 6 downstream of the fixing unit, but the other parts are the same, so the entire description is omitted.

  FIG. 3 is a block diagram illustrating a control relationship of the image forming apparatus G1.

  The control unit C1 of the image forming apparatus G1 is a computer system having a CPU, a memory M1, an arithmetic unit, an I / O port, a communication interface, a drive circuit, and the like.

  Control by the control unit C1 is performed by executing a predetermined program stored in the memory M1.

  The control unit C1 is connected to a network and can exchange information with other information processing devices.

  In the drawing, the description of blocks not directly related to the description of the present invention is omitted.

  FIG. 4 is a diagram for explaining the positional relationship between the paper conveyance path 100 and the air blowing members 201 and 202.

  The sheet conveyance path 100 shown in the figure is disposed downstream of the fixing unit 5, and the sheet P whose finishing edge has been detected and detected by the sheet detection sensor SP is used as the first sheet conveyance path 101 or the second sheet. This is a paper conveyance path leading to the conveyance path 102.

  At a point where the paper transport path 100 branches into the first paper transport path 101 and the second paper transport path 102, a first air blowing member 210 and a second air blowing member 220 that are air blowing nozzles that blow air onto the paper P are provided. Opposed to each other.

  Further, the direction of the blowing nozzle is not perpendicular to the surface of the paper P, but is arranged obliquely so that the tip of the nozzle faces the traveling direction of the paper P as shown in the figure. By providing such an inclination, air flows in the traveling direction of the paper P, and the conveyance of the paper is stabilized.

  FIG. 5 is a block diagram illustrating the configuration of the air blowing unit 200.

  The air blowing unit 200 includes a first air blowing member 210, an air valve 211, a second air blowing member 220, an air valve 221, an air tank 230, an air pump 240, an air duct 260, and the like.

  The air pump 240 sends air so that the air pressure of the air tank 230 maintains a predetermined pressure.

The air in the air tank is sent to the first air blowing member 210 or the second air blowing member 220 when the air valves 211 and 221 opened and closed by the instruction signals 219 and 229 of the controller C1 are opened. Further, when the valves 211 and 221 are closed , the air blowing to the first air blowing member 210 or the second air blowing member 220 is blocked.

  With such a configuration, the control unit C1 controls the timing of starting or blocking the blowing of air from the first blower member 210 or the second blower member 220.

  A first air amount changing unit 251 and a second air amount changing unit 252 whose positions are changed by instruction signals 218 and 228 of the control unit C1, respectively, are provided at the front ends of the first blowing member 210 and the second blowing member 220. It has been.

  That is, the control unit C1 controls the first air amount changing unit 251 and the second air amount changing unit 252 as to the amount of air per unit time that is blown out toward the paper P from the leading ends of the first air blowing member 210 and the second air blowing member 220. It is controlled by controlling.

  FIG. 6 is a diagram illustrating an example of the air amount changing unit. The first air amount changing unit 251 and the second air amount changing unit 252 have the same configuration.

  FIG. 6A is a conceptual diagram of the first air blowing member 210, and the air sent through the air duct 260 blows out from the slit-like air outlet 259 of the first air blowing member 210 in the direction of arrow f.

  The first air amount changing unit 251 is provided at the outlet of the first air blowing member 210. FIGS. 6B, 6 </ b> C, and 6 </ b> D are examples of the first air amount changing unit 251.

  FIG. 6B is an example in which the amount of air hitting the paper P is changed by moving the member 255 having small holes opened in a staggered pattern to the outlet of the first air blowing member 210.

  FIG. 2B shows an example in which the amount of air hitting the paper P is changed by moving the sawtooth member 256 at the outlet of the first air blowing member 210.

  FIG. 3C is an example in which the amount of air hitting the paper P is changed by opening and closing the member 257 that opens and closes symmetrically at the outlet of the first air blowing member 210.

  FIG. 7 is a flowchart showing the flow of air blowing control.

The air blowing control guides the paper P entering the paper transport path 100 to the first paper transport path 101 or the second paper transport path 102 by blowing air against the paper P in accordance with a preset job specification. Further, the control is performed to blow air for cooling the image surface of the paper P that further proceeds.

  When the leading edge of the paper P is detected by the paper detection sensor SP (step S1: Y), paper conveyance path selection information determined by the job specification set in the image forming apparatus G1 is acquired. Further, paper tip position information, which is the distance traveled by the tip of the paper P from the position of the paper detection sensor SP, is sequentially calculated from the transport speed of the paper P (step S2).

  If it is determined from the calculated leading edge position information that the leading edge of the sheet P has reached a preset position (step S3: Y), the first sheet is referred to with reference to the acquired sheet conveyance path selection information. It is determined whether or not the sheet P is sent to the transport path 101 (step S4).

If the sheet P is to be sent to the first sheet conveyance path 101, the second air valve 221 is opened so that air is blown out from the second blower member 220 below the sheet P (step S5 ). The amount of air blown out per unit time is determined by the second air amount changing unit 252.

  When the leading end of the sheet P is guided to the first sheet conveying path 101 by the air blown from the second air blowing member 220 and the leading end reaches a preset air amount changing position (step 6: Y), the second air amount The amount of air blown out from the second blowing member 220 is reduced by the changing unit 252 (step S7).

  Such a change in the amount of air blown from the second air blowing member 220 weakens the contact between the image surface of the paper P and the paper guide member of the first paper transport path 101, and the toner and wax on the paper surface are The problem of adhering to the paper guide member is reduced.

  In the above-described example, the front end portion of the paper P is guided to the first paper conveyance path 101 by the air blown from the second air blowing member 220 to make the explanation easy to understand. It is desirable that air is blown out from both of the air blowing members 220 and the leading end of the paper P is guided to the first paper transport path 101 by the difference in the amount of air blown out.

  As described above, the air is always applied to both sides of the paper P, so that the air always flows on the image surface of the paper P, and the toner image heated by the fixing unit 5 is quickly cooled, Further, the sliding contact between the paper P and the paper guide member is reduced, and the problem that the toner and wax on the paper surface adhere to the paper guide member is further reduced.

  When the trailing edge of the paper P is detected by the paper detection sensor SP (step S8: Y), or after a predetermined time has elapsed after detection, the open air valve is closed (step 12) and the routine is exited.

On the other hand, when the paper P is sent to the second paper conveyance path 102 in step S4 (step S4: N), the first air valve is used so that air blows out from the first air blowing member 210 above the paper P. 211 is opened (step S9 ). Note that the amount of air blown out per unit time is determined by the first air amount changing unit 251.

  When the leading end of the sheet P is guided to the second sheet conveying path 102 by the air blown from the first blower member 210 and the leading end reaches a preset air amount changing position (step S10: Y), the first air amount is reached. The amount of air blown from the first air blowing member 210 is reduced by the changing unit 251 (step S11).

  In the above example, the front end portion of the paper P is guided to the second paper conveyance path 102 by the air blown from the first air blowing member 210 for easy understanding, but the first air blowing member 210 and the second air blowing air. It is desirable that air be blown out from both of the members 220 and the leading end of the paper P be guided to the second paper transport path 102 by the difference in the amount of air blown out.

  As described above, air is constantly applied to both sides of the paper P, so that air always flows on the image surface of the paper P, and the toner image heated by the fixing unit 5 and the paper P are quickly cooled. In addition, sliding contact between the paper P and the paper guide member is reduced.

  As a result, the problem of toner and wax on the sheet surface adhering to the sheet guide member and the problem of curling due to the strong stress applied to the overheated sheet P are reduced.

  When the trailing edge of the paper P is detected by the paper detection sensor SP (step S8: Y), or after a predetermined time has elapsed after detection, the open air valve is closed (step 12) and the routine is exited.

It is a conceptual diagram of the conventional image forming apparatus. 1 is a conceptual diagram of an image forming apparatus according to the present invention. 3 is a block diagram illustrating a control relationship of the image forming apparatus. FIG. FIG. 6 is a diagram illustrating a positional relationship between a sheet conveyance path and a blower member. It is a block diagram explaining the structure of a ventilation part. It is a figure which shows the example of an air quantity change part. It is a flowchart which shows the flow of ventilation control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 Fixing part 100 Paper conveyance path 101 1st paper conveyance path 102 2nd paper conveyance path 200 Blower part 210 1st ventilation member 220 2nd ventilation member 251 1st air quantity change part 252 2nd air quantity change part C1 control part G1 Image forming device P Paper SP Paper detection sensor

Claims (8)

An image forming unit that forms a toner image on paper;
A fixing unit for fixing the Paper the toner image,
A paper transport path that branches into a first paper transport path and a second paper transport path downstream of the fixing unit;
By blowing air into the paper, a blowing portion for guiding the sheet to said first sheet transport path or the second paper transport path,
A control unit for controlling the blowing of the blowing unit ,
The image forming apparatus according to claim 1, wherein the control unit performs control to weaken the blowing of the air blowing unit while air is being blown onto the paper . The blowing unit includes a first blowing member for blowing air into the first side of the paper, is arranged opposite to the first blowing member, and the second blowing member for blowing air into the second surface of the sheet, the The image forming apparatus according to claim 1. The image forming apparatus according to claim 2, wherein the first air blowing member and the second air blowing member have a slit-shaped air outlet. Air blown from the first blower member and the second blowing member, after striking the surface of the sheet conveyed, so as to be directed in the direction of the front end of said sheet, said second blowing member and the first blowing member The image forming apparatus according to claim 2, wherein the image forming apparatus is arranged. The blowing unit, comprising: a first air amount changing unit for changing the amount of air blown out from the first blowing member, and a second air amount changing unit for changing the amount of air blown out from the second blowing member, the The image forming apparatus according to any one of claims 2 to 4. Said first air amount changing unit and the second air amount changing unit, to the air outlet, the opening area adjusting member for changing the opening area is provided, by moving the opening area adjusting member, said air outlet The image forming apparatus according to claim 5, wherein the amount of air blown from the air is changed. The blower is characterized in that it comprises a first air valve for turning on and off the balloon of air from the first blowing member, and a second air valve for turning on and off the balloon of air from the second blowing member The image forming apparatus according to claim 2. The controller is
Based on the signal sent from the paper detection sensor for detecting the leading edge of the sheet, to calculate the position information of the tip of paper for Ru is conveyed,
Based on the calculated positional information, the first air valve, and an image forming apparatus according to claim 7, wherein the determined Teisu Rukoto the on-off timing of the second air valve.

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