JP2009258444A - Intermediate transfer unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that effectively restrains the rise in temperature, in an intermediate transfer body and a photoreceptor, without generating powder dust of toner in an environment where the temperature in the apparatus rises to obtain a proper image. <P>SOLUTION: This image forming apparatus 1 includes an intermediate transfer unit 30 provided in an air duct 50, wherein the intermediate transfer unit includes an intermediate transfer body 10 for transferring a toner image on the photoreceptor 3; a plurality of structures including two or more rollers 11, 12 supporting the intermediate transfer body; a primary transfer roller 14, constituting a part of the plurality of structures to apply voltage to the inner surface of the intermediate transfer body; and an intermediate transfer frame 41 supporting the plurality of structures. The intermediate transfer frame includes a suction duct 71 for introducing cooling air in the air duct, into the intermediate transfer body, an exhaust duct 72 for discharging cooling air from the interior of the intermediate transfer body and a straightening vane 44 for passing the cooling air introduced from the suction duct through the periphery of the primary transfer roller. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an intermediate transfer unit having an intermediate transfer member supported by a plurality of components including a roller, and an image forming apparatus including the intermediate transfer unit.

  In an image forming apparatus (typically, a color laser printer), an intermediate transfer body for transferring toner images in a color-superimposed manner before transferring toner images formed on a plurality of image carriers onto transfer paper or the like is provided. Is provided. In particular, in a tandem type image forming apparatus, an endless intermediate transfer belt wound around a plurality of rollers is used as an intermediate transfer member.

  In this type of image forming apparatus, the temperature inside the apparatus rises due to heat radiation from various electrical components such as a fixing device. In particular, when the temperature of the intermediate transfer member or the photosensitive member rises too much, the toner melts in these image forming portions and partially aggregates, and transfer omission occurs in the central portion of a fine line image such as characters. In addition, when used for a long time, filming that is a film of a toner component is formed on the surface of the intermediate transfer member, and image defects such as color streaks occur.

  In a conventional image forming apparatus, a belt body such as an intermediate transfer belt is arranged in an air passage formed in the apparatus main body of the image forming apparatus in order to suppress temperature rise in the apparatus, and the photosensitive body is exposed to the belt body. There is a technique for cooling a drum (for example, see Patent Document 1).

However, in the technique described in Patent Document 1, since a belt body such as an intermediate transfer belt is merely disposed in an air passage formed in the apparatus main body of the image forming apparatus, an intermediate transfer body or a photoconductor (photosensitive) When the air volume is increased in order to increase the cooling effect, there is a problem that image contamination due to toner dust or in-device contamination occurs.
JP 2004233345 A

  The present invention has been made in view of the above-described problems of the prior art, and the object of the present invention is to generate an intermediate transfer member or toner without generating toner dust even in an environment where the temperature inside the apparatus rises. An object of the present invention is to provide an intermediate transfer unit and an image forming apparatus capable of effectively suppressing a temperature rise of a photoreceptor and obtaining a good image.

  The above object of the present invention is achieved by the following means.

  (1) An intermediate transfer member that transfers a toner image on a photosensitive member, a plurality of components including at least two or more rollers that support the intermediate transfer member, and a part of the plurality of components, the intermediate A primary transfer roller that applies a voltage to the inner surface of the transfer body; and an intermediate transfer frame that is disposed in an air passage in a housing of the image forming apparatus and supports the plurality of components. A suction duct for introducing the cooling air in the air passage into the intermediate transfer body, an exhaust duct for exhausting the introduced cooling air from the intermediate transfer body, and the cooling air introduced from the suction duct of the primary transfer roller. An intermediate transfer unit comprising: a baffle plate that passes around.

  (2) An image forming apparatus including an intermediate transfer unit, wherein the intermediate transfer unit includes an intermediate transfer body that transfers a toner image on a photoconductor and at least two or more rollers that support the intermediate transfer body. A plurality of constituents, a primary transfer roller that forms a part of the plurality of constituents and applies a voltage to the inner surface of the intermediate transfer member, and an intermediate transfer frame that supports the plurality of constituents, The intermediate transfer frame includes a suction duct for introducing cooling air in the air passage into the intermediate transfer body, an exhaust duct for exhausting the introduced cooling air from the intermediate transfer body, and cooling air introduced from the suction duct. An image forming apparatus comprising: a baffle plate that passes around the primary transfer roller.

  (3) The primary transfer roller includes a separation mechanism that separates the primary transfer roller from the intermediate transfer member, and the suction duct includes an opening / closing unit. When the primary transfer roller is separated, the opening / closing unit Is closed to stop the introduction of the cooling air to the primary transfer roller.

  (4) During standby or monochrome printing, the separation mechanism separates the primary transfer roller of a color other than black from the intermediate transfer member, and closes the opening / closing means to the primary transfer roller of a color other than black. The image forming apparatus according to (3), wherein the introduction of the cooling air is stopped.

  In the present invention, the frame of the intermediate transfer unit disposed in the air path of the image forming apparatus exhausts the introduced cooling air from the intermediate transfer body, with the suction duct for guiding the cooling air in the air path into the intermediate transfer body. Since it has an exhaust duct and a baffle plate that allows the air introduced from the suction duct to pass around the primary transfer roller, the cooling air is effectively applied to the periphery of the primary transfer roller in the intermediate transfer unit. be able to. Therefore, even in an environment where the temperature inside the apparatus rises, a good image can be obtained by effectively suppressing the temperature rise of the intermediate transfer member and the photosensitive member via the primary transfer roller without generating toner dust. Can be obtained.

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

  FIG. 1 is a schematic diagram illustrating a configuration of a main part of a printer as an image forming apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the printer 1 includes an imaging unit 2 for each color of yellow (Y), magenta (M), cyan (C), and black (K) in the printer body. Each imaging unit 2 includes a photosensitive drum 3 as a first image carrier made of a-Si (amorphous silicon) or the like, and rotates in the direction of the arrow in the drawing.

  The photosensitive drum (photosensitive member) 3 is first uniformly charged by the charging unit 30. Then, LED light 9 based on the original image data input from an external PC (personal computer) or the like, that is, writing light (image exposure) modulated by the image data is supplied from an exposure device (LED print head unit or the like) not shown. Irradiation on the surface of the photosensitive drum 3 forms an electrostatic latent image. Next, the toner supplied in the developing device 8 adheres to the electrostatic latent image to form a toner image. Here, yellow (Y), magenta (M), cyan (C), and black (K) toners are supplied.

  An endless intermediate transfer belt 10 (intermediate transfer member) as a second image carrier is wound between a driving roller 11 and a driven roller 12 above the imaging unit 2 for each color. It is rotated and arranged. The intermediate transfer belt 10 is pressed against each photosensitive drum 3 by the primary transfer roller 14 from the inside, and the driving roller 11 is driven to rotate by a motor or the like (not shown), whereby the rotation of the photosensitive drum 3 is performed. The vehicle travels in the forward direction.

  Then, the intermediate transfer belt 10 is sent from the intermediate transfer cleaning device 15 side to the secondary transfer unit 17 side, and each of the imaging units 2 of yellow (Y), magenta (M), cyan (C), and black (K). In the meantime, the toner image of each color on the surface of each photoconductive drum is electrostatically transferred to the intermediate transfer belt 10 by the voltage applied to the primary transfer roller 14, and the intermediate transfer belt 10 is successively the same. It is transferred (primary transfer) over the position. The secondary transfer unit 17 is configured by bringing the transfer roller 18 into contact with the driving roller 11 via the intermediate transfer belt 10.

  On the other hand, the recording paper 21 is fed from the paper supply mechanism 19 by the paper supply roller 20, and the recording paper 21 is conveyed to the intermediate transfer belt 10 (secondary transfer unit 17) side via the recording paper conveyance path 22. The registration roller 23 adjusts the timing of the image transfer operation and the paper feeding operation by the respective photosensitive drums 3 and the primary transfer roller 14. While the recording paper 21 is on standby by the registration rollers 23, the toner images of the respective colors on the surfaces of the photosensitive drums 3 are successively transferred to the intermediate transfer belt 10. After the timing adjustment, the registration roller 23 is rotated and the recording paper 21 is sent to the secondary transfer unit 17. In the secondary transfer portion 17, the toner image that has been primarily transferred to the intermediate transfer belt 10 is secondarily transferred to the recording paper 21.

  The recording paper 21 onto which the toner image has been transferred is conveyed to a fixing device 24 where it is heated and pressed to fix the toner image and form a color image. The recording paper 21 that has passed through the fixing device 24 is discharged from a discharge roller 25 to a discharge tray through a conveyance path.

  Next, the intermediate transfer unit 30 that is a main part of the printer 1 of the present embodiment will be described in more detail. FIG. 2 is a front view schematically showing the main part of the intermediate transfer unit 30. FIG. 3 is a plan view schematically showing the main part of the intermediate transfer unit 30. In FIG. 3, the lower part of the drawing is the front part of the printer 1, and the upper part of the drawing is the rear part of the printer 1.

  As shown in FIGS. 2 and 3, the intermediate transfer unit 30 of this embodiment includes an intermediate transfer belt 10 that transfers a toner image on the photosensitive drum 3, and a driving roller 11 and a driven roller 12 that support the intermediate transfer belt 10. A primary transfer roller 14 that forms a part of the plurality of components and applies a voltage to the inner surface of the intermediate transfer belt 10, and an intermediate transfer frame 41 that supports the plurality of components. Are generally provided.

  An intermediate transfer frame 41 is provided in the apparatus casing 51 of the printer 1, and an air passage 50 through which cooling air passes is defined in the casing 51. In FIG. 3, for example, the cooling air is introduced into the air passage 50 by forming an intake port 52 at the front portion of the left side surface of the casing 51 and an exhaust port 53 at the rear portion of the right side surface. By attaching an exhaust means 54 such as an exhaust fan to the opening 53, it is possible to introduce cooling air into the air passage 50.

  The intermediate transfer frame 41 has a front frame 42 and a rear frame 43, and the front frame 42 and the rear frame 43 are fixed upright with a space therebetween.

  In FIG. 2, the left end portion of the front frame 42 is connected to the left side surface of the housing 51 by the partition wall 61, and the right end portion is connected to the front surface of the housing 51 by the partition wall 62. An intake passage 55 communicating with the mouth 52 is defined. On the other hand, the right end portion of the rear frame 43 is connected to the right side surface of the casing 51 by the partition wall 63, and the left end portion is connected to the rear surface of the casing 51 by the partition wall 64. An exhaust passage 56 that communicates with each other is defined.

  The driving roller 11 and the driven roller 12 are rotatably supported at both ends between the front frame 42 and the rear frame 43. Further, a yellow (Y), magenta (M), cyan (C), and black (K) primary transfer roller 14 is rotatably supported between the driving roller 11 and the driven roller 12. The intermediate transfer belt 10 is wound around these rollers 11, 12 and 14.

  A suction duct 71 for introducing the cooling air in the intake passage 55 into the intermediate transfer belt 10 is provided at the portion of the front frame 42 where the primary transfer rollers 14 are arranged. On the other hand, an exhaust duct 72 for exhausting the introduced cooling air from the intermediate transfer belt 10 to the exhaust path 55 is provided at the portion of the rear frame 43 where the primary transfer rollers 14 are disposed. Then, cooling air introduced from a suction duct 71 surrounding each primary transfer roller 14 is erected on both sides of each primary transfer roller 14 so as to connect the front frame 42 and the rear frame 43. A rectifying plate 44 is disposed around the next transfer roller 10.

  FIG. 4 is a schematic cross-sectional view showing the opening / closing means 80 of the suction duct 71. FIG. 5 is a schematic diagram showing a state of interlocking between the separation mechanism 90 of the primary transfer roller 14 and the opening / closing means 80.

  As shown in FIGS. 4 and 5, on the front surface of the front frame 42, opening / closing means 80 for opening and closing each suction duct 71 is provided. The opening / closing means 80 is formed of, for example, a resin plate having the same number of openings 82 as the suction ducts 71, and is connected to a slidable shutter 81 and a drive source (not shown). And a cam 83 for slidingly moving the shutter 81. During ventilation, the opening 82 of the shutter 81 is aligned with the suction duct 71 of the front frame 42. In the shutter 81, the shutter 81 is pushed by the cam 83 in conjunction with the rotation of the cam 83 and a separation mechanism 90, which will be described later, and the closing portion that is the plate portion of the shutter 81 closes the suction duct 71, that is, the closed state. Is supposed to form. Here, the shutter 81 and the cam 83 are biased so as to contact each other by a biasing means such as a spring (not shown).

  The opening portion 82 of the shutter 81 and the closing portion of the shutter 81 are portions formed integrally with the shutter 81, and are not shown in FIG. Further, a closed portion of the shutter 81 may be formed at an end portion of the shutter 81, and the suction duct 71 may be opened when the closed portion is removed from the position of the suction duct 71. In this case, the opening 82 may be omitted.

  The bearing portion 14A of the primary transfer roller 14 is provided with a separation mechanism 90 that separates the primary transfer roller 14 from the voltage application position on the intermediate transfer belt 10 during standby or monochrome printing. The separation mechanism 90 includes, for example, a coil spring 91 connected to a fixing portion (hook) 84 of the shutter 81, a long piece 92A connected to the bearing portion 14A of the primary transfer roller 14, and a short piece 92B. The L-shaped lever member 92 connected to the extending end of the lever member 92 and a support pin 93 that rotatably supports the bent portion of the lever member 92.

  The separation mechanism 90 is interlocked with the opening / closing means 80. That is, when the shutter 81 is moved to the left by the cam 83 and the closing portion of the shutter 81 closes the suction duct 71, the lever member 92 having the support pin 93 as a fulcrum is rotated to the right, and the primary The transfer roller 14 is separated from the inner surface of the intermediate transfer belt. On the other hand, when the shutter 81 is moved rightward by the cam 83 and the opening 82 of the shutter 81 coincides with the position of the suction duct 71, the lever member 92 having the support pin 93 as a fulcrum is rotated to the left, The primary transfer roller 14 returns to the voltage application position on the intermediate transfer belt 10.

  The separation mechanism 90 is provided in each primary transfer roller 14, and the opening / closing means 80 is also provided in each suction duct 71. However, the separation mechanism 90 and the opening / closing means 80 may be provided only in the primary transfer roller 14 of a color other than black (K). During standby or monochrome printing, the primary transfer roller 14 of a color other than black (K) is separated, and the corresponding suction duct 71 is closed by the shutter 81. Thereby, more efficient cooling becomes possible.

  As described above, according to the intermediate transfer unit 30 of the present embodiment and the printer 1 incorporating the same, the components of the intermediate transfer unit 30 disposed in the air passage 50 defined in the apparatus housing 51. The intermediate transfer frame 41 includes a suction duct 71 for introducing cooling air into the intermediate transfer belt 10, an exhaust duct 72 for exhausting the introduced cooling air, and the introduced cooling air as the primary air. And a baffle plate 44 that is blown to the transfer roller and guided to the exhaust duct 72. Accordingly, the cooling air is directly applied to the periphery of the primary transfer roller 14 in the intermediate transfer unit 30 to suppress the temperature rise of the intermediate transfer belt 10 that is in contact with the primary transfer roller 14, and in the primary transfer portion. It is possible to suppress the temperature increase applied to the toner and prevent image defects due to the temperature increase.

  Further, since the cooling air flows inside the intermediate transfer belt 10, it does not flow to the image forming portion where the toner image is transferred from the photosensitive drum 3 to the intermediate transfer belt 10, and it is possible to suppress the diffusion of powder smoke due to the cooling air. . As a result, it is possible to prevent image stains and in-machine stains and to prevent toner from flowing out from the exhaust duct 72.

  Further, by applying cooling air around the primary transfer roller 10, it is possible to suppress the occurrence of image defects due to adhesion of foreign matters such as toner to the roller surface.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

  For example, the intermediate transfer unit according to the present invention is not limited to a printer of the illustrated type, but also to an electrophotographic image forming apparatus such as a copying machine equipped with a belt driving device or an MFP (Multiple Function Peripheral). It can be widely applied.

1 is a schematic diagram illustrating a configuration of a main part of a printer as an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a front view schematically showing a main part of an intermediate transfer unit. FIG. 3 is a plan view schematically showing a main part of an intermediate transfer unit. It is a schematic sectional drawing which shows the opening / closing means of a suction duct. FIG. 5 is a schematic diagram illustrating a state of interlocking between a primary transfer roller separation mechanism and an opening / closing means.

Explanation of symbols

1 image forming apparatus,
3 Photosensitive drum (photosensitive member)
10 Intermediate transfer belt,
11 Drive roller,
12 driven roller,
14 Primary transfer roller,
30 Intermediate transfer belt (intermediate transfer member),
41 Intermediate transfer frame,
42 Front frame,
43 Rear frame,
71 suction duct,
72 exhaust duct,
80 opening and closing means,
90 Separation mechanism.

Claims (4)

An intermediate transfer member for transferring a toner image on the photosensitive member;
A plurality of components including at least two or more rollers supporting the intermediate transfer member;
An intermediate transfer frame that is disposed in an air passage in a housing of the image forming apparatus and supports the plurality of components,
The plurality of components include a primary transfer roller that applies a voltage to the inner surface of the intermediate transfer member,
The intermediate transfer frame is
A suction duct for introducing cooling air in the air passage into the intermediate transfer body;
An exhaust duct for exhausting the introduced cooling air from the intermediate transfer body;
A rectifying plate for passing cooling air introduced from the suction duct around the primary transfer roller;
An intermediate transfer unit comprising: An image forming apparatus including an intermediate transfer unit,
The intermediate transfer unit is
An intermediate transfer member for transferring a toner image on the photosensitive member;
A plurality of components including at least two or more rollers supporting the intermediate transfer member;
An intermediate transfer frame that is disposed in an air passage in the housing of the image forming apparatus and supports the plurality of components,
The plurality of components include a primary transfer roller that applies a voltage to the inner surface of the intermediate transfer member,
The intermediate transfer frame is
A suction duct for introducing cooling air in the air passage into the intermediate transfer body;
An exhaust duct for exhausting the introduced cooling air from the intermediate transfer body;
A rectifying plate for passing cooling air introduced from the suction duct around the primary transfer roller;
An image forming apparatus comprising: The primary transfer roller includes a separation mechanism that separates the primary transfer roller from the intermediate transfer member, and the suction duct includes an opening / closing means,
3. The image forming apparatus according to claim 2, wherein when the primary transfer roller is separated, the opening / closing means is closed to stop the introduction of cooling air to the primary transfer roller.   During standby or monochrome printing, the separation mechanism separates the primary transfer roller of a color other than black from the intermediate transfer member, and closes the opening / closing means to cool air to the primary transfer roller of a color other than black. The image forming apparatus according to claim 3, wherein the image forming apparatus is stopped.

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