JP2007101788A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently cool a photoreceptor drum in an electrophotographic image forming apparatus such as a copying machine, laser printer or facsimile apparatus. <P>SOLUTION: An inlet 23 and an outlet 24 are formed in one and the other ends, respectively, of the photoreceptor drum 10, which has a photoreceptive layer 11 formed along the circumferential face of a cylindrical base 20 and is rotated and driven. An impeller, which is integrally rotated with the photoreceptor drum 10 and draws air from the inlet 23, is disposed in the inlet 23. Thereby, the drawn air is caused to flow toward the outlet 24 along the internal circumferential face of the cylindrical base 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a laser printer, and a facsimile machine.

  Conventionally, in an image forming apparatus that employs an electrophotographic system in which toner is electrostatically adsorbed to a photosensitive drum and transferred to a recording medium, a heat source such as a fixing device is used, so that the temperature inside the apparatus rises. It is known that the photosensitive drum is heated and deteriorates to cause problems in image formation. Particularly in recent image forming apparatuses, since the apparatus main body has been made more compact and the intervals between the devices in the apparatus have become narrower, the photosensitive drum is more susceptible to heat.

  Further, in the case of an image forming apparatus that performs double-sided printing on a recording medium, the recording medium is reversed after the image formed on one side is fixed by the fixing device, and image formation is performed again on the other side by the photosensitive drum. Is called. At this time, the recording medium on which the image formed on one side by the fixing device is fixed is transported again to the photosensitive drum in a state where the temperature is increased by receiving heat from the fixing device. The medium is heated and the temperature rises.

  In view of this, it is conceivable that a fan for cooling the photosensitive drum is provided in the image forming apparatus to blow air to the photosensitive drum. However, in this case, the toner electrostatically attracted to the outer peripheral surface of the photosensitive drum and the toner transferred to the recording medium before fixing are peeled off by the wind of the fan. As a result, the printing state of the recording medium is deteriorated, and further, the peeled toner is scattered inside the image forming apparatus, and image noise is given to other recording media.

  In order to cope with such a problem, Patent Document 1 discloses that an impeller is provided inside a hollow photosensitive drum having both ends opened, and the impeller is rotated in accordance with the rotation of the photosensitive drum. There is disclosed a technique in which air is taken into a photosensitive drum. According to this technique, the inside of the photosensitive drum is cooled without being blown to the outer peripheral surface of the photosensitive drum.

JP 2000-194230 A

  A photosensitive layer for forming an electrostatic latent image is coated on the outer peripheral surface of the photosensitive drum, and a defect in image formation occurs when the photosensitive layer is heated to change its characteristics. For this reason, the photosensitive drum is most required to cool the outer peripheral portion where the photosensitive layer is formed.

  However, in the technique described in Patent Document 1, the air is blown into the inside of the photosensitive drum, but the inner peripheral surface corresponding to the back surface of the photosensitive layer that needs the most cooling is not exposed to wind, and cooling is performed. ineffective.

  An object of the present invention is to enable efficient cooling of a photosensitive drum.

  The image forming apparatus of the present invention is formed by forming a photosensitive layer on the outer peripheral surface of a hollow cylindrical substrate and rotating the photosensitive drum, and opening the side surface on one end side in the axial direction of the cylindrical substrate. An intake port, an exhaust port formed to be opened on the side surface on the other end side in the axial direction of the cylindrical base, and an impeller that rotates integrally with the photosensitive drum and sucks air from the intake port, A cooling mechanism that blows the sucked air toward the inner peripheral surface of the cylindrical base and exhausts the air from the exhaust port.

  According to the present invention, since the air taken into the photoconductor drum is blown toward the inner peripheral surface, the photoconductor drum can be efficiently cooled.

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a longitudinal side view schematically showing an image forming apparatus according to the present embodiment. The image forming apparatus 1 includes a main body case 2. A paper feed cassette 4 on which a recording medium 3 is placed is attached to one end of the main body case 2, and image formation is performed on the other end of the main body case 2. A paper discharge tray 5 on which the recording medium 3 is discharged is attached.

  In the main body case 2, there are a photosensitive drum 10 and a transfer device 15, which will be described later, an image forming unit 6 that transfers a toner image onto the recording medium 3 by an electrophotographic process, and a toner transferred onto the recording medium 3. A fixing device 7 for fixing an image and a conveyance path 8 through which the recording medium 3 is conveyed from the paper feed cassette 4 to the paper discharge tray 5 through the image forming unit 6 and the fixing device 7 are provided. . A vent hole (not shown) is formed on both side surfaces of the main body case 2 so as to be positioned in the vicinity of the image forming unit 6.

  FIG. 2 is an enlarged vertical side view showing the image forming unit 6. The image forming unit 6 is formed on a photosensitive drum 10 that is rotated around a support shaft 9 integrally formed with a gear (not shown) driven by a motor (not shown), and on the outer peripheral surface of the photosensitive drum 10. A charger 12 for uniformly charging the photosensitive layer 11, an exposure device 13 for exposing the outer peripheral surface of the photosensitive drum 10 to form an electrostatic latent image according to image information, and a toner for the electrostatic latent image. A developer 14 that forms a toner image by adhering, a transfer unit 15 that contacts the photosensitive drum 10 to transfer the toner image onto the recording medium 3, and remains on the photosensitive drum 10 after the toner image is transferred. A cleaning blade 16 that removes the toner that is present, a registration roller 17 that measures the timing of feeding the recording medium 3 to the transfer position, and the like. The recording medium 3 sent to the transfer position between the photoconductor drum 10 and the transfer device 15 is rotated by the photoconductor drum 10 to transfer the toner image and conveyed to the fixing device 7 side.

  FIG. 3 is an enlarged vertical side view of the fixing device 7. The fixing device 7 includes a fixing roller 18 and a pressure roller 19. The fixing roller 18 generates heat when energized and is rotationally driven by a driving unit (not shown). The pressure roller 19 is disposed so as to be rotatable about an axis having an axis parallel to the axis of the fixing roller 18. The pressure roller 19 transfers the recording medium 3 onto which the toner image has been transferred and conveyed from the image forming unit 6 side. 18 to press. When the recording medium 3 to which the toner image has been transferred passes between the fixing roller 18 and the pressure roller 19, heat from the fixing roller 18 and pressure from the pressure roller 19 are applied to the recording medium 3, and recording is performed. The toner image on the medium 3 is fixed on the recording medium 3. Then, the recording medium 3 sandwiched between the fixing roller 18 and the pressure roller 19 is conveyed toward the paper discharge tray 5.

  Further, since the fixing device 7 includes the fixing roller 18 that generates heat, it becomes a heat source, and heat is radiated to other devices inside the main body case 2.

  Next, the photosensitive drum 10 will be described with reference to FIGS.

  4 is a longitudinal front view showing the photosensitive drum 10, FIG. 5 is a side view thereof, and FIG. 6 is a perspective view showing a mixed flow impeller 25 inside the photosensitive drum 10.

  The photosensitive drum 10 includes a hollow cylindrical base 20 formed of a metal material such as aluminum, a photoconductive semiconductor vapor deposition film formed by coating the outer peripheral surface of the cylindrical base 20, and an insulating layer covering the surface. And the photosensitive layer 11. In the vicinity of both ends of the cylindrical base body 20, flanges 21 and 22 formed of conductive synthetic resin are fixedly fitted, and the support shaft 9 penetrating through and fixed to the centers of the flanges 21 and 22 is the main body case 2. Is held on.

  The flanges 21 and 22 have openings 21a and 22a, and the hollow cylindrical base body 20 is configured to be penetrated so that air is taken into the inside. Here, the openings 21a and 22a are formed in a circular shape when viewed from the side, and are divided by a bridge B that connects the central portions 21c and 22c into which the support shaft 9 is fitted and the outer peripheral portions 21b and 22b. (See FIG. 4B).

  In the cylindrical base body 20, one end side provided with the flange 21 is referred to as an intake port 23, and the other end side provided with the flange 22 is referred to as an exhaust port 24.

  The flange 21 is formed such that the diameter of the opening 21a is gradually reduced from the intake port 23 toward the exhaust port 24. On the other hand, the flange 22 on the exhaust port 24 side is formed such that its opening 22a gradually increases in diameter as it goes from the exhaust port 24 toward the intake port 23. Therefore, the outer peripheral portions 21b and 22b of the flanges 21 and 22 have different thicknesses along the axial direction.

  Further, the hollow cylindrical base body 20 is provided with a mixed flow impeller 25 mounted on the support shaft 9 so as to be positioned slightly on the exhaust port 24 side of the flange 21 on the intake port 23 side. The mixed flow impeller 25 is configured to exhaust the sucked air in an oblique direction with respect to the support shaft 9.

  The mixed flow impeller 25 is attached in such a direction that air is sucked into the cylindrical substrate 20 from the air inlet 23 when the photosensitive drum 10 is rotated in a direction in which the toner image is transferred and the recording medium 3 is conveyed. Since the shaft 9 is mounted on the support shaft 9, the photosensitive drum 10 is rotated as it is driven to rotate about the support shaft 9.

  On the other hand, on the exhaust port 24 side inside the cylindrical base body 20, an axial flow impeller 26 that is positioned slightly closer to the intake port 23 side than the flange 22 and exhausts the sucked air in the axial direction of the support shaft 9. 9 is mounted on the shaft. When the photosensitive drum 10 is rotated in the direction in which the photosensitive drum 10 transfers the toner image and transports the recording medium 3, the axial flow impeller 26 is attached in a direction for sucking the air inside the cylindrical base 20, and the mixed flow impeller 25. Similarly, it is rotated as the photosensitive drum 10 rotates. The axial flow impeller 26 is formed so that the outer diameter indicated by the arrow L is slightly smaller than the inner diameter of the cylindrical base body 20, and there is a slight gap between the outer diameter of the axial flow impeller 26 and the inner diameter of the cylindrical base body 20. There is a gap.

  In this configuration, in the image forming apparatus 1, the recording medium 3 fed from the paper feed cassette 4 is transported along the transport path 8, and the toner image is transferred in the image forming unit 6 in the transport process. Then, the transferred toner image is fixed by the fixing device 7, and the recording medium 3 on which the toner image is fixed is discharged onto the discharge tray 5.

  At this time, when the photosensitive drum 10 is rotated in the image forming unit 6, the mixed flow impeller 25 mounted on the support shaft 9 is also rotated, and air is taken into the cylindrical base body 20 from the outside through the air inlet 23. It is.

  FIG. 7 is a longitudinal front view of the photosensitive drum 10 for explaining the flow of air taken in from the air inlet 23. The air flow is indicated by arrow A. Since the mixed flow impeller 25 exhausts in an oblique direction with respect to the support shaft 9, the taken-in air is blown toward the inner peripheral surface of the cylindrical base body 20. Since the axial impeller 26 mounted on the support shaft 9 is also rotated by the rotation of the photosensitive drum 10, the air blown toward the inner peripheral surface of the cylindrical base body 20 by the mixed flow impeller 25 is this shaft. The air is sucked by the rotation of the flow impeller 26 and exhausted to the outside through the exhaust port 24. Here, a cooling mechanism is realized.

  Here, if the diameter of the axial flow impeller 26 is small, the air blown toward the inner peripheral surface of the cylindrical base body 20 by the mixed flow impeller 25 is supported when being exhausted by the axial flow impeller 26. The air is sucked in the direction of the shaft 9. However, the diameter of the axial flow impeller 26 has such a size that there is only a slight gap between it and the inner diameter of the cylindrical base body 20 as described above. Therefore, the air blown toward the inner peripheral surface of the cylindrical base body 20 is sucked so as to proceed in the axial direction in a state along the inner peripheral surface of the cylindrical base body 20 without approaching the direction of the support shaft 9. The air is exhausted from the exhaust port 24.

  The flanges 21 and 22 connect the support shaft 9 and the cylindrical base body 20 and maintain the shape of the cylindrical base body 20. Therefore, if the inner diameter of the opening 22a of the flange 22 is increased and the outer peripheral portion is made thinner, the strength of the flange 22 itself is weakened, and the maintenance of the shape of the cylindrical base 20 is hindered. Therefore, it is desirable that the inner diameter of the opening 22a is small from the viewpoint of strength. On the other hand, if the inner diameter of the opening 22a is small, the air flowed in the axial direction by the axial flow impeller 26 collides with the end portion of the flange 22 on the axial flow impeller 26 side, and the air is disturbed at the position indicated by symbol B in FIG. Flow is likely to occur. However, according to the configuration of the present embodiment, the opening 22a of the flange 22 is enlarged from the axial end of the photosensitive drum 10 toward the center, in other words, as shown in FIG. Since the cross-sectional shape becomes smaller toward the center in the axial direction, both the strength of the flange 22 and the prevention of turbulence can be achieved.

  In addition, since a mixed flow impeller 25 (so-called centrifugal impeller) is used as a configuration for directing toward the inner peripheral surface of the cylindrical base body 20, good cooling can be realized with a simple configuration. In addition, since an axial flow impeller 26 that exhausts air discharged from the mixed flow impeller 25 in the axial direction toward the exhaust port 24 is provided on the exhaust port 24 side, air is efficiently transferred from the intake port 23 to the exhaust port 24. From this point, the cooling effect of the photosensitive drum 10 can be improved.

In the present embodiment, the mixed flow impeller 25 is provided as a mechanism for taking air into the cylindrical base body 20 on the intake port 23 side and blowing it to the inner peripheral surface of the cylindrical base body 20, but the present invention is not limited to this. Further, a centrifugal impeller that exhausts in a direction perpendicular to the support shaft 9 and a rectifying plate that guides the exhausted air toward the inner peripheral surface of the cylindrical base 20 may be provided inside the cylindrical base 20.

1 is a longitudinal side view schematically showing an image forming apparatus of the present embodiment. It is a vertical side view which expands and shows an image formation part. FIG. 2 is a longitudinal side view showing the fixing device in an enlarged manner. It is a longitudinal front view showing a photosensitive drum. It is a side view which shows a photoconductor drum. It is a perspective view which shows the mixed flow impeller inside a photoconductive drum. FIG. 3 is a longitudinal front view of a photosensitive drum for explaining a flow of air taken in from an intake port.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 9 Support shaft 10 Photosensitive drum 11 Photosensitive layer 20 Cylindrical base | substrates 21 and 22 Flange 21a, 22a Opening part 23 Intake port 24 Exhaust port 25 Diagonal flow impeller 26 Axial flow impeller

Claims (4)

A photosensitive drum that is rotationally driven with a photosensitive layer formed on the outer peripheral surface of a hollow cylindrical base;
An air inlet formed to be opened on a side surface on one end side in the axial direction of the cylindrical base;
An exhaust port formed to be opened on the side surface on the other end side in the axial direction of the cylindrical base;
A cooling mechanism having an impeller that rotates integrally with the photosensitive drum and sucks air from the air intake port, and blows the sucked air toward the inner peripheral surface of the cylindrical base to exhaust the air from the exhaust port;
An image forming apparatus comprising: The cooling mechanism is
It is provided inside the cylindrical base on the side of the air inlet and is rotated integrally with the photosensitive drum so that the air sucked from the air inlet is directed toward the inner peripheral surface of the cylindrical base with respect to the axial direction. The image forming apparatus according to claim 1, further comprising a mixed flow impeller that exhausts at an angle. The cooling mechanism is
Provided on the exhaust port side inside the cylindrical substrate, and rotated integrally with the photosensitive drum, the air discharged from the mixed flow impeller is exhausted in the axial direction of the cylindrical substrate toward the exhaust port. The image forming apparatus according to claim 2, further comprising an axial flow impeller. The photosensitive drum includes a flange that is provided in the vicinity of both ends of the cylindrical base and connects the cylindrical base and a spindle that is driven to rotate, and has a circular opening.
4. The image forming apparatus according to claim 1, wherein the opening of the flange provided on the exhaust port side has a diameter that increases from an axial end of the photosensitive drum toward a center.

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