JP2007033914A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image forming apparatus capable of preventing dew condensation caused by water vapor by ejecting heat generated by a fixing device and water vapor discharged from a recording medium. <P>SOLUTION: Paper is heated by the fixing device 38 in order to fix a toner image on the paper. Thus, the fixing device 38 generates the heat, and also moisture contained in the paper becomes the water vapor and is discharged. The heat generated by the fixing device 38 and the water vapor discharged from the paper rise and pass through a gap provided between a guiding member 48 and an auxiliary member 50 and are ejected from an aperture part 46 through a ventilation flue 44. The water vapor is ejected only from the aperture part 46 without being diffused in a housing 12 by an air course forming member 12A and an air course forming auxiliary member 56, so that the dew condensation is not caused in the housing 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus provided with a fixing device.

In the image forming apparatus, a toner image is formed on a recording medium by an image forming unit, and the toner image on the recording medium is fixed by a fixing device. (Patent Document 1)
Specifically, the toner image on the photosensitive drum is transferred onto a sheet (recording medium), and then the toner image on the sheet is fixed by being heat-pressed by a fixing roller, and the sheet is discharged by a discharge roller. It is discharged to the tray. Here, when the sheet is heated and pressure-bonded by the fixing roller, moisture contained in the sheet is released as water vapor. The discharged water vapor and the heat generated by the fixing roller are sucked by the fan and discharged outside through the duct.

This prevents condensation in the image forming apparatus and prevents paper jamming, paper contamination, and paper deformation caused by water droplets adhering to the paper.
JP-A-7-160179

  However, according to this image forming apparatus, the cost of the image forming apparatus is increased due to the installation of the fan. Further, when the image forming apparatus is used, the fan is operated, so that the power consumption increases and the running cost increases. Become.

  On the other hand, as a means for preventing condensation in the image forming apparatus, there is a technique in which a plurality of openings are provided on the side surface of the fixing device. Leaking into the door may cause noise.

  In consideration of the above-mentioned fact, the present invention eliminates the heat generated by the fixing device and the water vapor released from the recording medium without installing a fan or by blocking the sound from the opening, so that dew condensation due to the water vapor is generated. An object of the present invention is to provide an image forming apparatus that can be prevented.

  An image forming apparatus according to claim 1 of the present invention includes an image forming unit that forms a toner image on a recording medium, a fixing device that fixes the toner image to the recording medium by heating and melting, and the image forming unit. And a housing in which the fixing device is housed and an opening is formed in an upper portion of the fixing device, the steam generated from the recording medium heated by the fixing device is used only for the opening. The ventilation path forming member which comprises the ventilation path discharged from the inside is provided in the housing | casing, It is characterized by the above-mentioned.

  According to the above configuration, when the toner image formed in the image forming unit is fixed on the recording medium by the fixing device, the fixing device generates heat, and moisture contained in the recording medium is released as water vapor. Is done. The heat generated by the fixing device and the water vapor released from the recording medium pass through the ventilation passage provided in the housing by the ventilation passage forming member and are discharged only from the opening provided in the upper portion of the fixing device.

  Here, since heat and water vapor are discharged only from the opening provided in the upper part of the fixing device, it is not necessary to provide the housing on the side of the fixing device. As a result, the running sound of the recording medium and the driving sound of the fixing device are prevented from leaking out of the apparatus.

  Further, since all the water vapor is discharged from the opening through the ventilation path, the water vapor does not flow into the gap in the housing and cause dew condensation without providing a fan.

  An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein a guide member for guiding the recording medium to a discharge port for discharging the recording medium is provided between the fixing device and the ventilation path. The guide member is provided with a gap for allowing water vapor and heat to pass therethrough.

  According to the above configuration, since the guide member that is disposed between the fixing device and the ventilation path and guides the recording medium to the discharge port is provided with a gap that allows water vapor and heat to pass therethrough, the heat generated by the fixing device can be reduced. The water vapor released from the recording medium passes through the gap between the guide members and is discharged from the opening. As a result, the recording medium is guided to the discharge port, and no condensation occurs on the guide member. Therefore, the paper jam, the paper stain, and the paper deformation caused by the water droplets adhering to the paper do not occur.

  An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein the ventilation path includes an air path formation assisting member disposed on an openable / closable door provided in the housing. When the door is closed, the air path forming member and the air path forming auxiliary member are in close contact with each other to form the ventilation path.

  According to the above configuration, the door that can be opened and closed is arranged in the housing. Therefore, maintenance in the image forming apparatus can be performed by opening the door. Further, when the door is closed, the air path forming auxiliary member disposed in the door and the air path forming member disposed in the housing are in close contact with each other, so that the heat generated by the fixing device and the water vapor released from the recording medium are It is reliably discharged from the opening without leaking from between the path forming member and the air path forming auxiliary member.

  According to the image forming apparatus of the present invention, the heat generated by the fixing device and the water vapor released from the recording medium are discharged without installing a fan or by sound insulation from the opening, and dew condensation due to the water vapor is generated. Can be prevented.

  A first embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS.

  As shown in FIG. 4, the image forming apparatus 10 includes a housing 12 that is a housing. In the first embodiment, a developing unit 24Y that forms a yellow toner image in the housing 12 and a magenta toner image are formed. A developing unit 24M that forms a cyan toner image, and a developing unit 24K that forms a black toner image are arranged in the vertical direction in order from the top. In addition, when it is necessary to distinguish YMCK, it demonstrates by attaching | subjecting any one of Y, M, C, and K after a code | symbol, and when it is not necessary to distinguish YMCK, YMCK is abbreviate | omitted.

  On the other hand, the photosensitive member cartridge 18 includes a drum-shaped photosensitive member 22 and a charging roll 26 that charges the surface of the photosensitive member 22. An optical scanning device 14 corresponding to each color for exposing the surface of the photoconductor 22 to form an electrostatic latent image is disposed adjacent to the photoconductor cartridge 18.

  Further, the developing rollers 20 provided in the developing devices 24Y, 24M, 24C, and 24K respectively convert the electrostatic latent image on the photosensitive member 22 to yellow (Y), magenta (M), cyan (C), and black (K). Develop with toner.

  Further, a transfer roll 30 for transferring the toner image of the photosensitive member 22 to a sheet (not shown) as a recording medium is disposed to face the photosensitive member 22 and constitutes an image forming unit.

  On the other hand, a paper feed cassette 16 for storing paper is provided at a lower portion in the housing 12. The paper feed cassette 16 is provided with a feed roll 32 that feeds paper at a predetermined timing. A nip transport roll 34 is provided in a paper transport path 28 located between the feed roll 32 and the developing device 24K. An optical paper passage sensor 36 is disposed on the downstream side of the nip conveyance roll 34 in the paper conveyance direction.

  The paper passage sensor 36 detects the leading edge of the paper, and the electrostatic latent image writing timing of each optical scanning device 14 is controlled based on the detection timing. Further, a fixing path 38 for fixing the toner image onto the sheet by heat-pressing the toner image is provided in the conveying path 28 located downstream of the developing unit 24Y in the sheet conveying direction. The fixing unit 38 has a built-in heater. The heating roll 38A and the pressure roll 38B are provided.

  A guide member 48 (described later) and a discharge roll 40 for discharging the paper are provided on the downstream side of the fixing device 38 in the paper conveyance direction. The paper on which the toner image has been transferred is guided by the guide member 48 and discharged from the discharge roll 40. As a result, the sheet is discharged to the storage tray 42 formed on the upper surface of the housing 12.

  In the image forming apparatus 10 configured as described above, an image is formed as follows.

  First, the charging roll 26 to which a voltage is applied uniformly negatively charges the surface of the photosensitive member 22 with a predetermined charged portion potential.

  Subsequently, exposure is performed by the optical scanning device 14 so that an image portion on the charged photosensitive member 22 has a predetermined exposure portion potential, and an electrostatic latent image is formed.

  That is, a latent image corresponding to an image is formed on the photosensitive member 22 by turning on / off the optical scanning device 14 based on video data supplied from a control device (not shown).

  A developing bias set in advance for each color is applied to the developing roller 20 of the developing device 24, and the latent image is developed with toner when passing through the position of the developing roller 20, and is visualized as a toner image.

  Therefore, the sheet passes between the photosensitive member 22 and the transfer roll 30, and the toner image is transferred to the sheet. The transferred toner image is heat-pressed by passing between a heating roll 38A and a pressure roll 38B provided in the fixing device 38, and is fixed on the paper. Here, when the paper is heated, the water contained in the paper becomes water vapor, and the water vapor and the heat generated by the fixing device 38 pass through an air passage 44 formed by an air passage forming member 12A, which will be described later, from the opening 46. Discharged.

  Further, the sheet is guided to a discharge port by a guide member 48 described later, and discharged to a storage tray 42 formed on the upper portion of the housing 12 by a discharge roll 40.

  Next, members constituting the ventilation path 44, which is a path for water vapor released from the paper when the paper passes through the fixing device 38, will be described in detail.

  As shown in FIG. 1, the fixing device 38 that fixes a toner image on a sheet includes a heating roll 38 </ b> A and a pressure roll 38 </ b> B incorporating a heater. When the paper passes through here, the water contained in the paper becomes water vapor and is discharged upward (in the direction of arrow C).

  A guide member 48 and an auxiliary member 50 are provided above the fixing unit 38 so that the sheet is guided along the conveyance path 28. The guide member 48 includes an oblique surface 48A that guides the sheet to the discharge roll 40 side by changing the conveyance path 28 by approximately 90 ° when viewed from the axial direction of the heating roll 38A, and a substantially water surface 48B that is fixed to the housing 12. Yes. Further, when viewed from the axial direction of the heating roll 38A, the auxiliary member 50 has its tip overlapped with the inclined surface 48A of the guide member 48 to prevent the paper from turning around to the side opposite to the discharge roll 40 side. The proximal end is attached to a door 52 described later.

  As shown in FIG. 3, the guide member 48 and the auxiliary member 50 are arranged at equal intervals along the axial direction of the heating roll 38 </ b> A, and enter the gap between the adjacent guide member 48 and auxiliary member 50. A gap through which water vapor and heat pass is provided.

  As shown in FIG. 1, an opening 46 through which water vapor is discharged is provided in the housing 12 at an upper portion of the guide member 48, and water vapor is disposed between the opening 46 and the guide member 48 in the housing 12. An air passage forming member 12A is formed integrally with the housing 12 so as not to diffuse inside. The air passage forming member 12 </ b> A extends downward from the end of the opening 46 to prevent water vapor from diffusing and forms a ventilation passage 44 that is a passage for water vapor. Here, the mounting plate 54 to which the guide member 48 is mounted and the air path forming member 12A on the discharge roll 40 side are orthogonal to each other at the point A, and the end of the mounting plate 54 is the air path at the point A. It does not protrude from the forming member 12A.

  On the other hand, as shown in FIG. 2, a door 52 that can be opened and closed is provided on the side surface of the housing 12 for maintenance of the image forming apparatus 10. The center of rotation of the door 52 is provided at a lower portion of the housing 12, and the door 52 is configured to open and close the side surface of the housing 12. Inside the door 52 is provided an air passage formation assisting member 56 that forms the air passage 44 together with the air passage forming member 12A. When the door 52 is opened, the air passage formation assisting member 56 and the air passage forming member 12A are separated from each other. Thus, when the door 52 is closed, as shown in FIG. 1, the air passage formation assisting member 56 and the air passage forming member 12A are in close contact so that water vapor does not pass therebetween.

  Next, the operation of the guide member 48 and the air path forming member 12A will be described.

  As shown in FIG. 1, in order to fix the toner image formed by the image forming unit on the paper, the paper is heated by passing between a heating roll 38 </ b> A and a pressure roll 38 </ b> B of the fixing device 38. As a result, the fixing device 38 generates heat, and moisture contained in the paper is released as water vapor.

  The heat generated by the fixing device 38 and the water vapor released from the paper rise (arrow C) and pass through the gaps formed in the guide member 48 and the auxiliary member 50, thereby forming the air path forming member 12A and the air path forming auxiliary member 56. Is discharged from the opening 46 through the ventilation path 44 (arrow D). Here, since water vapor passes through a gap formed in the guide member 48, no condensation occurs on the guide member 48. Further, the air path forming member 12A and the air path forming auxiliary member 56 do not diffuse the water vapor into the housing 12, and all the water vapor is discharged from the opening 46, so that the water vapor flows into the gap in the housing 12. Does not cause condensation.

  On the other hand, as shown in FIG. 2, a door 52 that can be opened and closed is provided on the side surface of the housing 12 for maintenance of the image forming apparatus 10, and an air passage formation auxiliary member 56 is provided inside the door 52. It has been. When the door 52 is closed, the air passage formation assisting member 56 and the air passage forming member 12 </ b> A are in close contact with each other so that water vapor does not pass therebetween, thereby forming the air passage 44. For this reason, water vapor is discharged from the opening 46 without diffusing.

  Accordingly, since the water vapor is discharged from the opening 46 without flowing into the gap in the housing 12, there is no condensation in the housing 12, and paper jams, paper stains, and paper deformation caused by water droplets adhering to the paper are prevented. It is prevented.

  Further, since heat and water vapor are discharged only from the opening 46 provided with the ventilation path 44, it is not necessary to provide a plurality of openings in the housing 12 on the side of the fixing device 38. For this reason, leakage of the running sound of the paper, the driving sound of the fixing device 38, and the like to the outside of the housing 12 is suppressed.

  Next, a second embodiment of the image forming apparatus of the present invention will be described with reference to FIG.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 5, the mounting plate 58 to which the guide member 48 is mounted and the air path forming member 12A on the discharge roll 40 side are orthogonal to each other at point B. In this embodiment, in the first embodiment, as shown in FIG. Unlike this, at the point B, the end of the mounting plate 58 protrudes from the air passage forming member 12A. Further, a curved portion 12B is provided at the upper end portion of the air passage forming member 12A on the discharge roll 40 side, and the upper end portion of the curved portion 12B is connected to the end portion of the opening 46.

  The operation of the second embodiment is the same as that of the first embodiment. Therefore, when the end of the mounting plate 58 protrudes from the air passage forming member 12A due to design constraints, the water vapor can be discharged out of the housing 12 by providing the curved portion 12B.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the first embodiment, the air passage forming member 12A formed integrally with the housing 12 forms the air passage 44. However, the present invention is not limited to this, and an air passage forming member separate from the housing is arranged. A ventilation path may be formed.

FIG. 2 is a cross-sectional view illustrating the image forming apparatus according to the first exemplary embodiment of the present invention, in which the fixing device and an upper portion thereof are viewed from the axial direction of a heating roll. FIG. 2 is a cross-sectional view of the image forming apparatus according to the first embodiment of the present invention when the door 52 is opened with respect to FIG. 1. FIG. 2 is a perspective view illustrating the image forming apparatus according to the first embodiment of the present invention and illustrating the guide member and the auxiliary member 50 illustrated in FIG. 1. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating an image forming apparatus according to a second embodiment of the present invention and corresponding to FIG. 1 of the first embodiment.

Explanation of symbols

10 Image forming apparatus 12 Housing (housing)
12A Air path forming member 38 Fixing device 44 Ventilation path 46 Opening portion 48 Guide member 52 Door 56 Air path forming auxiliary member

Claims (3)

An image forming unit for forming a toner image on a recording medium;
A fixing device for fixing the toner image on the recording medium by heating and melting;
A housing in which the image forming unit and the fixing device are housed, and an opening is formed in an upper portion of the fixing device;
In an image forming apparatus comprising:
An image forming apparatus, wherein a ventilation path forming member constituting a ventilation path for discharging water vapor generated from the recording medium heated by the fixing device only from the opening is provided in the housing.   A guide member for guiding the recording medium to a discharge port for discharging the recording medium is provided between the fixing device and the ventilation path, and a gap for allowing water vapor and heat to pass is provided in the guide member. The image forming apparatus according to claim 1.   The ventilation path includes an air path formation auxiliary member disposed on an openable / closable door provided in the housing, and when the door is closed, the air path formation member and the air path formation auxiliary member are in close contact with each other. The image forming apparatus according to claim 1, further comprising an air passage.

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