JP2008003412A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of occurrence of heat affecting with respect to a unit which is sensitive to heat in both-side printing in the conventional image forming apparatuses. <P>SOLUTION: The image forming apparatus is provided with a reverse transport path 510 transporting transfer material on which an image is fixed on one side to an image forming part again; a transport roller 520 provided to the reverse transport path 510; a transport roller 530 provided on a farther downstream side of the transport roller 520 in the reverse transport path 510; a cooling fan 540 provided between the transport roller 520 and the transport roller 530 and blowing air to transfer material transported on the transport path 510; and a duct 550 provided in between the conveying roller 520 and the conveying roller 530 and discharging the air blown to the outside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine having a double-sided conveyance mechanism that guides a sheet on which toner is fixed in a fixing unit to a fixing unit again via a double-sided conveyance unit.

  In recent years, image forming apparatuses represented by copiers and the like are strongly required to increase the image quality and speed. However, a certain amount of heat is required to fix the toner on the paper, and such speed increases. As the process proceeds, a phenomenon occurs in which the sheet is not sufficiently cooled after the toner is fixed by the fixing unit.

  Due to this phenomenon, when a sheet with heat during double-sided printing moves through the transport path in the machine, there may be a thermal effect on heat sensitive units such as an image transfer unit including a development system. .

  In view of this, some conventional image forming apparatuses take away heat from the sheet discharged from the fixing unit by bringing a roller and a belt into contact with the sheet.

  Here, the configuration and operation of the conventional image forming apparatus 1 will be described in detail with reference to FIG. 8 which is a partial cross-sectional view of the conventional image forming apparatus (for example, see Patent Document 1).

  Inside the main body 2 of the image forming apparatus 1, a fixing unit 10, a sheet conveying unit 20, and a cooling unit 30 are provided.

  The paper transport unit 20 is provided immediately downstream of the fixing unit 10, and is disposed so that a part of the transport belt 21 is close to and parallel to the inner surface of the side wall of the housing 3 of the main body 2.

  The cooling unit 30 includes a cooling fan 31 and a suction fan (not shown).

  The cooling fan 31 is disposed on the inner surface of the housing 3 parallel to the transport belt 21, and a vent hole 33 is provided in the wall portion of the inner surface of the housing 3 parallel to the transport belt 21.

  A suction duct (not shown) is arranged such that a suction duct 34 is in contact with the transport belt 21 from the inside immediately downstream of the fixing unit 10.

  According to such a configuration, air is forced to flow by the operation of the cooling unit 30.

Accordingly, since heat is not accumulated on the conveyor belt 21, the sheet can be sufficiently cooled.
JP 2004-198863 A

  However, in such an image forming apparatus 1, a path is not secured until the forced air is exhausted to the outside of the apparatus, and the heated air warms the internal space.

  For this reason, the image forming apparatus 1 may end up with a thermal effect on the heat-sensitive unit during double-sided printing.

  An object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of a thermal effect on a heat-sensitive unit during double-sided printing in consideration of the above-described conventional problems.

The first aspect of the present invention includes an image forming unit that forms an image on a transfer material
An image fixing unit for fixing the formed image to the transfer material;
A reverse conveyance path for conveying again the transfer material having the image fixed on one side thereof to the image forming unit;
A first transport roller provided in the reverse transport path;
A second transport roller provided downstream of the first transport roller in the reverse transport path;
A fan that is provided between the first transport roller and the second transport roller and blows air against the transfer material transported to the reverse transport path;
The image forming apparatus includes an exhaust hole provided between the first transport roller and the second transport roller and configured to discharge the blown air to the outside.

  The second aspect of the present invention is the image forming apparatus according to the first aspect of the present invention, wherein the fan is provided on the downstream side of the exhaust hole of the reverse conveyance path.

  The third aspect of the present invention is the image forming apparatus according to the second aspect of the present invention, wherein an angle formed between the direction in which the air is blown and the direction in which the transfer material is transported through the reverse transport path is an obtuse angle.

4th this invention is equipped with the detection part which detects the state in which the said transfer material is conveyed in the said reverse conveyance path,
The fan is the image forming apparatus according to the first aspect of the invention in which the timing of blowing the air is controlled according to the detection result.

  According to a fifth aspect of the present invention, in the fourth aspect, the timing is controlled so that the fan blows the air when it is detected that the transfer material is conveyed in the vicinity of the second conveyance roller. The image forming apparatus of the present invention.

  A sixth aspect of the present invention is the image forming apparatus according to the first aspect of the present invention, wherein the fan is provided at a position where the air is blown against one side of the transfer material on which the image is fixed.

The seventh aspect of the present invention includes a plate having a plurality of holes disposed in an opening portion of the exhaust hole to the reverse conveyance path,
In the image forming apparatus according to the first aspect of the present invention, the size of the hole is smaller in an area where the end portion of the transfer material conveyed along the reverse conveyance path contacts than in other areas.

In an eighth aspect of the present invention, the first transport roller has a cylindrical shape having a width of the reverse transport path,
The second transport roller is the image forming apparatus according to the first aspect of the present invention having a cylindrical shape having a width of the reverse transport path.

  The present invention has an advantage in that it is possible to provide an image forming apparatus capable of suppressing the occurrence of a thermal effect on a heat-sensitive unit during duplex printing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
First, the configuration of the image forming apparatus according to the present embodiment will be described with reference mainly to FIG. 1 which is a schematic sectional view of the image forming apparatus according to the first embodiment of the present invention.

  The paper feed unit 100 is a unit having a paper tray for storing a transfer material on which printing is performed, a roller for supplying the transfer material to the image transfer unit 200, and the like.

  The image transfer unit 200 is a photosensitive drum to be exposed, a charger for charging the surface of the photosensitive drum, a light is applied to the surface of the photosensitive drum other than the portion where the image is formed to remove the charged charges, and an electrostatic latent image is formed. This means includes an exposure device to be formed, and a transfer device that applies a charge opposite to the toner from the opposite side of the photosensitive drum to the transfer material and transfers the toner to the transfer material by electrostatic force.

  The fixing unit 300 is a unit having a fixing roller having a heater, a pressure roller in pressure contact with the fixing roller, and the like.

  The paper discharge unit 400 is a unit having a discharge tray on which a transfer material on which an image is formed is placed.

  The double-sided conveyance unit 500 is a unit having a conveyance roller 520 that guides the transfer material on which toner is fixed in the fixing unit 300 to the fixing unit 300 again, a conveyance roller 530 provided on the downstream side of the conveyance roller 520, and the like.

  The sheet reversing unit 600 nips the transfer material conveyed from the duplex conveying unit 500 and replaces the front end and the rear end thereof to reverse the front and rear of the transfer material, and the front roller and the front roller reverse the front and rear. This means includes a middle roller that nips and conveys the transferred transfer material, and a subsequent roller that supplies the transfer material conveyed from the middle roller to the image transfer unit 200.

  A feature of the configuration of the image forming apparatus according to the present embodiment is that, when double-sided printing is performed, double-sided conveyance that cools a transfer material having a heat quantity by blowing air in order to suppress the thermal influence on other units. Characteristic of unit 500.

  Therefore, the configuration of the double-sided conveyance unit 500 will be described in more detail with reference mainly to FIG. 2 which is a schematic cross-sectional view of the double-sided conveyance unit 500 according to Embodiment 1 of the present invention.

  The double-sided conveyance unit 500 includes a reverse conveyance path 510 that again conveys a transfer material having an image fixed on one side to the image transfer unit 200, a conveyance roller 520 provided in the reverse conveyance path 510, and a conveyance roller of the reverse conveyance path 510. A conveyance roller 530 provided on the downstream side of 520, and a cooling fan 540 provided between the conveyance roller 520 and the conveyance roller 530 for blowing air to the transfer material conveyed to the reverse conveyance path 510. , And a duct 550 provided between the transport roller 520 and the transport roller 530 for discharging the blown air to the outside.

  In addition, the duplex conveyance unit 500 includes a paper detection switch 561 and a paper detection switch 562 that detect a state in which the transfer material is conveyed along the reverse conveyance path 510.

  Here, each component of the duplex conveyance unit 500 will be described in more detail.

  The reverse conveyance path 510 is a conveyance path through which the transfer material having an image fixed on one side is conveyed again to the image transfer unit 200.

  The reverse conveyance path 510 is formed so that the transfer material is conveyed downward in the vertical direction using the guide plate 511 and the guide plate 512 facing the guide plate 511.

  The guide plate 511 has a rib having a height of about 2 mm provided so as to guide both ends of the transfer material in the direction indicated by the arrow X along which the transfer material is conveyed through the reverse conveyance path 510. .

  Similar to the guide plate 511, the guide plate 512 has a height of about 2 mm provided so that both ends of the transfer material can be guided in the direction indicated by the arrow X along which the transfer material is conveyed through the reverse conveyance path 510. It has a rib.

  The conveyance roller 520 is a roller provided in the reverse conveyance path 510.

  The conveyance roller 520 has a cylindrical shape with the width of the reverse conveyance path 510 and is formed using a resin such as rubber or polyacetal.

  For this reason, the air that is blown onto the transfer material having a heat quantity by the cooling fan 540 and heated by the convection heat transfer from the transfer material does not easily escape to the upstream side of the conveying roller 520.

  The conveyance roller 530 is a roller provided on the downstream side of the conveyance roller 520 in the reverse conveyance path 510.

  Similarly to the transport roller 520, the transport roller 530 has a cylindrical shape with the width of the reverse transport path 510, and is formed using a resin such as rubber or polyacetal.

  For this reason, the air heated by the convective heat transfer as described above is unlikely to escape to the downstream side of the transport roller 530.

  The cooling fan 540 has an opening to the reverse conveyance path 510 between the conveyance roller 520 and the conveyance roller 530 and has been conveyed to the reverse conveyance path 510 provided inside the duct communicating with the outside. It is a fan that blows air against the transfer material.

  The cooling fan 540 is provided on the downstream side of the duct 550 of the reverse conveyance path 510.

  For this reason, the air blown to the transfer material having the heat quantity by the cooling fan 540 and heated by the convection heat transfer from the transfer material is expanded in volume and rises due to the buoyancy effect, and is easily discharged outside from the duct 550 .

  In addition, even when the cooling fan 540 is stopped, natural air cooling is performed by the chimney effect in which the heated air is naturally discharged from the duct 550 to the outside.

  The angle formed between the direction indicated by the arrow Y to which air is blown and the direction indicated by the arrow X along which the transfer material is conveyed through the reverse conveyance path 510 is an obtuse angle.

  For this reason, when the vector representing the wind speed in the reverse conveyance path 510 is decomposed into a vector in the paper passing direction and a vector in the direction perpendicular to the paper passing direction in the paper surface of FIG. Since it has a discharge direction (that is, a direction opposite to the direction indicated by the arrow X) and has a sufficient size, convective heat transfer as described above is efficiently performed.

  The cooling fan 540 is provided at a position on the exterior cover side where air can be blown to one side of the transfer material on which the image is fixed.

  For this reason, the sheet reversing unit 600 is provided on the downstream side of the duplex conveying unit 500, and air can be blown on one side of the heated surface in contact with the fixing roller of the fixing unit 300.

  As will be described in more detail later, the cooling fan 540 has a control unit (not shown) that blows air so that air is blown when it is detected that the transfer material is being conveyed in the vicinity of the conveyance roller 530. ).

  For this reason, the blowing is mainly performed in a state where at least the front end of the transfer material is engaged with the conveyance roller 530, and the transfer material can be prevented from flapping inside the reverse conveyance path 510.

  The duct 550 is an exhaust hole that is provided between the transport roller 520 and the transport roller 530 and discharges the blown air to the outside.

  The plate 551 is a plate provided with a plurality of holes, which is disposed at the opening of the duct 550 to the reverse conveyance path 510.

  Here, FIG. 3A is a schematic plan view of the plate 551 according to the first embodiment of the present invention, and FIG. 3A is a schematic right side view of the plate 551 according to the first embodiment of the present invention. The configuration of the plate 551 will be described in more detail with reference to B).

  The plate 551 comes into contact with the end portion of the transfer material conveyed along the reverse conveyance path 510 in consideration of the maximum paper width value W1 to be printed on both sides and the maximum paper width value W2 to be printed on both sides. Round holes are formed in the region D2 and the region D4, and long holes are formed in the other regions D1, the region D3, and the region D5.

  The size of the hole is smaller in the region D2 and the region D4 than in the other region D1, the region D3, and the region D5.

  For this reason, it is possible to sufficiently secure the exhaust efficiency while suppressing the transfer material from being sucked into the duct 550 and being caught by the sheet passing area of the plate 551.

  The plate 551 has a boundary between the region D1 and the region D2 and a region D2 and the region D3 so that both ends of the transfer material can be guided in the direction indicated by the arrow X along which the transfer material is conveyed along the reverse conveyance path 510. The rib R1, the rib R2, the rib R3, and the rib R4 each having a height of about 2 mm are provided at the boundary, the boundary between the region D3 and the region D4, and the boundary between the region D4 and the region D5.

  The paper detection switch 561 is provided in the vicinity of the conveyance roller 520, and is turned on when the transfer material is being conveyed in the vicinity of the conveyance roller 520, and is turned off in the other cases. Is a detector having an actuator that detects the state of being conveyed along the reverse conveyance path 510.

  The paper detection switch 562 is provided in the vicinity of the transport roller 530, and is turned on when the transfer material is transported in the vicinity of the transport roller 530, and is turned off in other cases. Is a detector having an actuator that detects the state of being conveyed along the reverse conveyance path 510.

  The distance between the paper detection switch 561 and the paper detection switch 562 is shorter than the length of the transfer material.

  The image transfer unit 200 corresponds to the image forming unit of the present invention.

  The fixing unit 300 corresponds to the image fixing unit of the present invention.

  The reverse conveyance path 510 corresponds to the reverse conveyance path of the present invention.

  Further, the transport roller 520 corresponds to the first transport roller of the present invention.

  Further, the transport roller 530 corresponds to the second transport roller of the present invention.

  The cooling fan 540 corresponds to the fan of the present invention.

  The duct 550 corresponds to the exhaust hole of the present invention.

  The unit including the paper detection switch 561 and the paper detection switch 562 corresponds to the detection unit of the present invention.

  Next, the operation of the image forming apparatus of the present embodiment will be described.

  While describing the operation of the image forming apparatus of the present embodiment, an embodiment of the image forming method of the invention related to the present invention will also be described.

  The paper supply unit 100 supplies a transfer material to the image transfer unit 200, the toner is transferred to one surface of the transfer material supplied by the image transfer unit 200, and the fixing unit 300 fixes the transferred toner.

  When single-sided printing is performed, the transfer material fixed on one side of the toner is discharged as it is to the paper discharge unit 400.

  When duplex printing is performed, the duplex conveyance unit 500 conveys the transfer material on which the toner is fixed to the sheet reversing unit 600, and the sheet reversing unit 600 reverses the front and back of the transfer material and then transfers the transfer material to the image. Supply to unit 200.

  The image transfer unit 200 transfers the toner to the other side of the transfer material supplied again, and the fixing unit 300 fixes the transferred toner.

  Then, the transfer material fixed on both sides of the toner is discharged to the paper discharge unit 400.

  The feature of the operation of the image forming apparatus according to the present embodiment is that, when double-sided printing is performed, double-sided conveyance that cools a transfer material having a heat quantity by blowing air in order to suppress the thermal influence on other units. The unit 500 is in operation.

  Therefore, the operation of the duplex conveyance unit 500 will be described in more detail.

  Step 1: Transfer material 1000 fixed on one side of the toner is conveyed from the fixing unit 300 side, the paper detection switch 561 is turned on, and the paper detection switch 562 remains off. The description will be given with reference.

  FIG. 4 is an explanatory diagram (part 1) of the operation of the duplex conveying unit 500 according to the first embodiment of the present invention.

  The cooling fan 540 is stopped when the paper detection switch 561 is on and the paper detection switch 562 remains off.

  For this reason, the transfer material 1000 is quickly conveyed by the conveyance roller 520 without flapping inside the reverse conveyance path 510.

  As described above, the heated air is naturally discharged from the duct 550 to the outside by the chimney effect even when the cooling fan 540 is stopped.

  Of course, useless power consumption is suppressed because the cooling fan 540 is stopped.

  Step 2: The case where the transfer material 1000 is further conveyed, the paper detection switch 561 remains on, and the paper detection switch 562 is also turned on will be described with reference mainly to FIG.

  FIG. 5 is an explanatory diagram (part 2) of the operation of the duplex conveying unit 500 according to the first embodiment of the present invention.

  The cooling fan 540 operates when the paper detection switch 561 remains on and the paper detection switch 562 is also on.

  For this reason, the transfer material 1000 is quickly conveyed by the conveying roller 520 and the conveying roller 530 while being cooled by the air blow performed by the cooling fan 540.

  The air heated by the cooling fan 540 blown onto the transfer material 1000 also helps the duct effect caused by the formation of a space surrounded by the guide plate 511, the conveyance roller 520, the transfer material 1000, and the conveyance roller 530. The gas is discharged from the duct 550 to the outside without passing through an extra route.

  Of course, the transfer material 1000 does not flutter inside the reverse conveyance path 510 because the front end is engaged with the conveyance roller 530 and the rear end is engaged with the conveyance roller 520.

  Step 3: The case where the transfer material 1000 is further conveyed, the paper detection switch 561 is turned off, and the paper detection switch 562 remains on will be described with reference mainly to FIG.

  FIG. 6 is an explanatory diagram (part 3) of the operation of the duplex conveying unit 500 according to the first embodiment of the present invention.

  The cooling fan 540 is still operating when the paper detection switch 561 is off and the paper detection switch 562 remains on.

  For this reason, the transfer material 1000 is quickly conveyed by the conveyance roller 530 while being cooled by the air blow performed by the cooling fan 540.

  The air whose temperature is increased by being blown onto the transfer material 1000 by the cooling fan 540 is discharged outside from the duct 550 without passing through an extra path.

  Of course, the transfer material 1000 flutters to the extent that the paper passing is stagnated in the reverse conveyance path 510 because the front end is engaged with the conveyance roller 530, although the rear end is not engaged with the conveyance roller 520. There is no end.

  Step 4: The case where the transfer material 1000 is conveyed to the paper reversing unit 600 side, the paper detection switch 561 is turned off, and the paper detection switch 562 is also turned off will be described with reference mainly to FIG.

  FIG. 7 is an explanatory diagram (part 4) of the operation of the duplex conveying unit 500 according to the first embodiment of the present invention.

  The cooling fan 540 is stopped when the paper detection switch 561 is off and the paper detection switch 562 is also off.

  For this reason, the transfer material 1000 is quickly conveyed by the conveyance roller 530 without fluttering inside the reverse conveyance path 510.

  As described above, the heated air is naturally discharged from the duct 550 to the outside by the chimney effect even when the cooling fan 540 is stopped.

  Of course, useless power consumption is suppressed because the cooling fan 540 is stopped.

  Thus, in the present embodiment, it is possible to suppress the occurrence of thermal influence on heat sensitive units such as the image transfer unit 200 during double-sided printing.

  The first embodiment of the present invention has been described in detail above.

  Note that Steps 1 to 4 described in the first embodiment are repeated in this order when the paper is continuously fed. Therefore, in Steps 1 and 4, the cooling fan 540 is stopped. You can just turn off the output instead.

  In addition, the program of the invention related to the present invention causes the computer to execute the operation of the step of controlling the timing at which the fan blows air according to the detection result of the image forming method of the invention related to the present invention described above. Which is a program that operates in cooperation with a computer.

  The recording medium of the invention related to the present invention causes the computer to execute the operation of the step of controlling the timing at which the fan blows air according to the detection result of the image forming method of the invention related to the present invention described above. A recording medium in which a program for recording is recorded, is readable by a computer, and is a recording medium in which the read program executes an operation in cooperation with the computer.

  Further, one use form of the program of the invention related to the present invention may be an aspect in which the program is recorded on a recording medium such as a ROM readable by a computer and operates in cooperation with the computer.

  The computer described above is not limited to pure hardware such as a CPU, and may include firmware, an OS, and peripheral devices.

  As described above, the configuration of the invention related to the present invention may be realized by software or hardware.

  INDUSTRIAL APPLICABILITY The present invention can provide an image forming apparatus that can suppress the occurrence of thermal effects on a heat-sensitive unit during duplex printing, and is useful as a copying machine.

1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. Schematic sectional view of double-sided conveyance unit 500 of Embodiment 1 in the present invention (A) Schematic plan view of the plate 551 according to the first embodiment of the present invention, (B) Schematic right side view of the plate 551 according to the first embodiment of the present invention. Explanatory drawing of operation | movement of the double-sided conveyance unit 500 of Embodiment 1 in this invention (the 1) Explanatory drawing of operation | movement of the double-sided conveyance unit 500 of Embodiment 1 in this invention (the 2) Explanatory drawing of operation | movement of the double-sided conveyance unit 500 of Embodiment 1 in this invention (the 3) Explanatory drawing of the operation | movement of the double-sided conveyance unit 500 of Embodiment 1 in this invention (the 4) Partial sectional view of a conventional image forming apparatus

Explanation of symbols

500 Double-sided transport unit 510 Reverse transport path 511 Guide plate 512 Guide plate 520 Transport roller 530 Transport roller 540 Cooling fan 550 Duct 551 Plate 561 Paper detection switch 562 Paper detection switch X arrow Y arrow

Claims (8)

An image forming unit for forming an image on a transfer material;
An image fixing unit for fixing the formed image to the transfer material;
A reverse conveyance path for conveying again the transfer material having the image fixed on one side thereof to the image forming unit;
A first transport roller provided in the reverse transport path;
A second transport roller provided downstream of the first transport roller in the reverse transport path;
A fan that is provided between the first transport roller and the second transport roller and blows air against the transfer material transported to the reverse transport path;
An image forming apparatus comprising: an exhaust hole provided between the first transport roller and the second transport roller for discharging the sprayed air to the outside.   The image forming apparatus according to claim 1, wherein the fan is provided on the downstream side of the exhaust hole of the reverse conveyance path.   The image forming apparatus according to claim 2, wherein an angle formed by a direction in which the air is blown and a direction in which the transfer material is conveyed along the reverse conveyance path is an obtuse angle. A detection unit that detects a state in which the transfer material is conveyed along the reverse conveyance path;
The image forming apparatus according to claim 1, wherein a timing of blowing the air is controlled according to a result of the detection.   The image forming apparatus according to claim 4, wherein the timing of the fan is controlled so that the air is blown when it is detected that the transfer material is being conveyed in the vicinity of the second conveyance roller. .   The image forming apparatus according to claim 1, wherein the fan is provided at a position where the air is blown against one side of the transfer material on which the image is fixed. A plate provided with a plurality of holes disposed in an opening of the exhaust hole to the reverse conveyance path;
2. The image forming apparatus according to claim 1, wherein the size of the hole is smaller in a region where the end of the transfer material conveyed along the reverse conveyance path contacts than in other regions. The first transport roller has a cylindrical shape having a length of the width of the reverse transport path,
The image forming apparatus according to claim 1, wherein the second conveying roller has a cylindrical shape having a width of the reverse conveying path.

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