JP2009204845A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an excessive temperature rise by efficiently cooling the detachable unit of an image forming apparatus incorporating a heat generation source. <P>SOLUTION: The image forming apparatus includes: a detachable unit 17, which incorporates the heat generation source and is detachable from the main body of the image forming apparatus; and a heat transmission section 45 that can transmit heat, generated by the detachable unit 17, to the main body. The heat transmission section 45 has: a heat transmission member in which a first contact portion that can be made in surface contact with the peripheral part 48 of the detachable unit 17 and a second contact portion that can be made in surface contact with the metal side wall 49 of the main body are continuously disposed; and a pressure contact mechanism that brings the first and second contact portions into firm contact with the peripheral part 48 of the detachable unit 17 and the metal side wall 49 of the main body respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a heat source and a detachable unit that is detachable from the main body of the image forming apparatus, and a heat transfer unit that can transfer heat derived from the detachable unit to the main body.

Examples of the detachable unit having a built-in heat source and detachable from the main body of the image forming apparatus include an optical unit that forms an electrostatic latent image on an image carrier (photosensitive drum) based on image data, and development. Examples include a developing unit that stirs and conveys the agent (toner, carrier) and supplies the image carrier to the image carrier, and a scanner motor, a developer, and the like in these units can each serve as a heat source.
Therefore, as a conventional image forming apparatus capable of cooling the detachable unit that can generate heat as described above, for example, as disclosed in FIG. 4 of Patent Document 1, there is a heat between the optical unit and the image forming apparatus main body. 2. Description of the Related Art An image forming apparatus that cools an optical unit by transmitting a heat derived from the optical unit to a main body of the image forming apparatus via a metal plate spring as a transmission unit is known.

JP 2004-61785 A

However, in the image forming apparatus of Patent Document 1, since the metal plate spring is brought into line contact with the optical unit, there is a problem that heat conduction efficiency is very poor and it is difficult to obtain a sufficient cooling effect.
The present invention has been made in view of the above circumstances, and an object of the present invention is to efficiently cool an attachment / detachment unit of an image forming apparatus having a built-in heat source to suppress an excessive temperature rise.

In order to achieve the above object, in the invention according to claim 1 of the present invention,
An image forming apparatus including a heat source and a detachable unit that is detachable from the main body of the image forming apparatus, and a heat transfer unit that can transmit heat derived from the detachable unit to the main body,
A heat conducting member in which the heat transfer part is continuously connected in series with a first contact part capable of being in surface contact with the peripheral wall part of the detachable unit and a second contact part capable of being in surface contact with the metal side wall of the main body; A pressure contact mechanism that presses the first contact portion and the second contact portion against the peripheral wall portion of the detachable unit and the metal side wall of the main body, respectively.

[Action and effect]
In the image forming apparatus of the present invention, the heat transfer part capable of transferring heat derived from the detachable unit to the image forming apparatus main body, the first contact part capable of being in surface contact with the peripheral wall part of the detachable unit, and the image forming apparatus main body. Since the heat transfer member in the present invention has a metal plate spring in the conventional image forming apparatus that is in line contact with the detachable unit, since the heat transfer member in the present invention is provided with a series of the second contact portion that can come into surface contact with the metal side wall. Compared to the above, heat conduction efficiency is very high, and heat derived from the detachable unit can be quickly transmitted to the image forming apparatus main body.

In addition, since the heat transfer unit according to the present invention includes a pressure contact mechanism that presses the first contact portion and the second contact portion against the peripheral wall portion of the detachable unit and the metal side wall of the image forming apparatus main body, respectively. The first contact portion and the second contact portion of the heat transfer portion by the pressure contact mechanism, even if the distance between the portion and the metal side wall of the image forming apparatus main body is slightly different from the reference dimension, It is possible to ensure surface contact with the peripheral wall portion of the detachable unit and the metal side wall of the image forming apparatus main body.
Therefore, according to the present invention, it is possible to cool the detachable unit containing the heat source more efficiently than the conventional image forming apparatus by the action of the heat transfer section, and the excessive temperature rise. Can be more reliably suppressed.

In the invention according to claim 2 of the present invention,
An aluminum foil is used as the heat conducting member, a sponge is used as the pressure contact mechanism, and the heat transfer portion is configured by covering the outer peripheral surface of the sponge with the aluminum foil.

[Action and effect]
The heat transfer portion in the present invention has a very simple configuration in which the outer peripheral surface of the sponge is covered with an aluminum foil, and can be manufactured inexpensively and easily.
Therefore, the heat transfer unit does not greatly increase the manufacturing cost for the image forming apparatus of the present invention.
Furthermore, since the heat transfer part in the present invention uses a sponge as a pressure contact mechanism, it is easy to set a pressing force smaller than a metal plate spring or the like in a conventional image forming apparatus, and as a result, the heat transfer part is It can be installed more easily between the detachable unit and the image forming apparatus main body.

Embodiments of the present invention will be described below with reference to the drawings.
Embodiment
(Overall configuration of image forming apparatus)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows the structure of a multifunction machine 1 that is an example of the image forming apparatus of the present invention. A sheet feeding unit 3 is disposed below the apparatus main body 2 of the multifunction machine 1. The sheet feeding unit 3 is provided with two-stage cassettes 4 along the height direction of the main body 2, and each of the cassettes 4 in this embodiment is on the front side (see FIG. 1). It can be pulled out toward the front side. Each cassette 4 stores sheets S before image formation in a stacked state, and the sheets S are separated one by one from the sheet feeding unit 3 and sent to the right.

A paper transport unit 5 is disposed on the right side of the paper feed unit 3, and the paper delivered from the paper feed unit 3 is transported upward along the right side surface of the main body 2. Next, the sheet S is reversed toward the left side in the main body 2 and is conveyed toward the left side as it is.
On the other hand, a manual sheet feeder 6 is provided above the cassette 4. Various types of recording materials that are fed one by one, such as paper of a size that is not in the cassette 4, thick paper, or OHP sheet, are placed on the paper feeding unit 6. Then, the recording material from the sheet feeding unit 6 joins the sheet conveying unit 5 and is conveyed toward the left side.

  Inside the main body 2, a registration roller 7, an image forming unit 8, and a transfer unit 9 are arranged in order on the downstream side in the paper conveyance direction from the conveyance unit 5. An optical unit 10, for example, an LSU (laser scanning unit) is provided above the image forming unit 8, and a laser is directed from the optical unit 10 toward the photosensitive drum (image carrier) 11 of the image forming unit 8. Light is irradiated.

Further, a fixing unit 12 and a discharge / branching unit 13 are sequentially arranged on the downstream side of the transfer unit 9 when viewed in the paper transport direction. In the case of single-sided printing, the paper S discharged from the fixing unit 12 is discharged / branched. The sheet is discharged to the sheet receiving tray 14 through the section 13.
On the other hand, a duplex printing unit 15 is disposed between the discharge / branch unit 13 and the paper feed unit 3. The unit 15 directs the paper S discharged from the fixing unit 12 toward the paper transport unit 5. The sheet is conveyed and sent again to the image forming unit 8.

  Here, the image forming unit 8 according to the present exemplary embodiment includes four image forming units. These units are arranged in order from the right side to the left side in FIG. 1, and are provided corresponding to images of four different colors (black, cyan, magenta, and yellow), and are charged, exposed, developed, and transferred, respectively. Through these steps, black, cyan, magenta and yellow images are sequentially formed.

Specifically, each unit of the image forming unit 8 is provided with a drum 11 that carries a visible image (toner image) of each corresponding color. Each drum 11 is rotatably installed with respect to the main body 2 and is driven counterclockwise in the figure by a drive motor (not shown).
Corresponding chargers 16, developing units 17, cleaning units 18, and intermediate transfer rollers 19 are provided at appropriate positions around each drum 11.

  The charger 16 uniformly charges the surface of the corresponding drum 11. In the developing unit 17, toners of black, cyan, magenta, and yellow are supplied from the toner containers 20 of the respective colors via the hopper 21, and electrostatically adhere to the surface of the drum 11 using the toner. Let As a result, a toner image corresponding to the electrostatic latent image by the optical unit 10 is developed on the surface of the drum 11. The toner images formed on these drums 11 are sequentially transferred onto the intermediate transfer belt 22 and synthesized as a toner image for one page.

Specifically, the belt 22 is an endless belt in which both end portions of a dielectric resin sheet material are overlapped and joined, or a seamless belt without a seam, and is shown in FIG. Drive clockwise.
The belt 22 runs between the drums 11 and the intermediate transfer rollers 19, whereby the toner images respectively formed on the drums 11 are primarily transferred onto the belt 22. In each cleaning unit 18, the toner remaining on the drum 11 is removed.

In the multifunction machine 1, the sheet S from the cassette 4 and the recording material from the manual sheet feeding unit 6 reach the registration roller 7. The roller 10 feeds the sheet to the transfer unit 9 while correcting the oblique feeding of the sheet S and measuring the timing with the toner image formed by the image forming unit 8.
Further, based on image data from a controller (not shown), the multifunction device 1 controls the irradiation of the laser beam by the optical unit 10. As a result, an electrostatic latent image of a document image is formed on each drum 11 in the image forming unit 8, and then a toner image is formed on the drum 11 from the latent image, and the transfer unit 9 is interposed via the intermediate transfer belt 22. Is transferred onto the paper S.

The sheet S is fed toward the fixing unit 12 with an unfixed toner image carried thereon, and the toner image is fixed by the heat roller at the fixing unit 12. Next, the sheet discharged from the fixing unit 12 is discharged to the tray 14 through the discharge / branch unit 13.
When double-sided printing is performed in contrast to this single-sided printing, the paper S discharged from the fixing unit 12 is pulled back to the unit 15 immediately before being discharged to the tray 14, and this paper is joined to the paper transport unit 5. Then, it is sent again toward the transfer section 9. In this case, the toner image is transferred to the other side of the paper that has not been printed.

(Development unit)
FIG. 2 is a longitudinal sectional view showing a state in which the developing unit 17 (an example of the detachable unit in the present invention) is connected to a metal side wall 49 provided on the main body side via a heat transfer portion 45. .
Each developing unit 17 shown in FIG. 1 is configured to be detachable from the main body 2, and is configured to be connected to the main body 2 via the heat transfer unit when installed in the main body 2. Yes. Details of the developing unit 17 will be described below.

The developing unit 17 in the present embodiment employs a method that combines a two-component developing method and a one-component developing method. That is, non-magnetic toner is charged using a magnetic carrier, and only the charged toner is caused to fly toward the drum 11, and the toner image is developed on the drum 11 by a non-contact developing method.
As shown in FIG. 2, the developing unit 17 includes a housing 23. The housing 23 has an opening 24 facing the drum 11, a peripheral wall 25 extending upward from the opening 24, and the peripheral wall 25. And a bottom wall 26 formed below.

Peripheral wall ducts 27 and 28 are provided at appropriate positions of the peripheral wall 25, and the peripheral wall 25 is cooled by air from a fan (not shown).
On the other hand, a stirring mixer 29 and a paddle mixer 30 are disposed on the bottom wall 26, and a developer (carrier and toner) is stored therein. The shafts 31 and 32 of the mixers 29 and 30 are rotatably supported with respect to the housing 23. When the mixers 29 and 30 are driven to rotate, the developer (carrier and toner) is agitated to charge the toner. Then, the developer is conveyed toward the scooping roller 33 via the mixer 30.

The shaft 34 of the pumping roller 33 is also supported rotatably with respect to the housing 23. When the roller 33 is rotated by a driving force of a driving unit (not shown) via a gear, the charged developer (carrier and toner) is conveyed to a magnetic brush roller (magnetic roller) 35.
The magnetic brush roller 35 is disposed on the upper right side of the mixer 30 as viewed in FIG. 2, and the brush roller 35 is also supported rotatably with respect to the housing 23.

  Specifically, the brush roller 35 has a shaft 36 at the center, and flanges are disposed at both ends of the shaft 36 via bearings, and a tubular brush-side sleeve 37 is integrally fitted on the outer periphery of the flange. Are combined. When this flange is rotated by the driving force of the driving unit via the gear, the sleeve 37 rotates clockwise in FIG.

  In the brush side sleeve 37, magnetic poles are arranged on the outer peripheral side of the shaft 36 with a predetermined magnetic force and angle, and the magnetic brush is drawn by attracting the developer (carrier and toner) from the pumping roller 33. Let it form. As a result, the magnetic brush is formed on the outer peripheral surface of the sleeve 37 in the region having the magnet.

The thickness of the magnetic brush is regulated by a panning blade 38 installed in the vicinity of the peripheral wall duct 27, and when a predetermined direct current (DC) bias or alternating current (AC) bias is applied, the magnetic brush becomes toner. Is conveyed toward the developing roller 39. On the other hand, this magnetic brush scrapes off the developed toner layer from the developing roller 39.
As described above, in the magnetic brush, the strongly adhered toner layer is peeled off from the developing roller 39 by a mechanical force, and new toner necessary for development is supplied to the developing roller 39.

  According to the magnetic brush described above, it is not necessary to provide a special device such as a scraping blade for the toner after development. This magnetic brush contacts the toner layer of the developing roller 39, and the rollers 35, 39 The collection and conveyance of the toner are facilitated by the brush effect due to the difference in rotational speed and the replacement of the developer of the magnetic brush by agitation in the mixers 29 and 30.

The developing roller 39 is disposed in the vicinity of the opening 24 at the lower right of the brush roller 35 as seen in FIG.
The shaft 40 of the roller 39 is arranged in parallel with the rotation axis of the brush roller 35, and the developing roller 39 is also supported by the housing 23 so as to be rotatable. That is, the developing roller 39 also has a shaft 40 at the center, and flanges are disposed on both ends of the shaft 40 via bearings, and a tubular developing side sleeve 41 is integrally fitted on the outer periphery of the flange. Has been. When the flange rotates through the gear, the sleeve 41 rotates in the clockwise direction in FIG.

  Due to the potential difference between the brush roller 35 and the developing roller 39, a layer of only the toner transferred from the brush roller 35 is formed on the developing roller 39. Simultaneously with the formation of the toner layer on the developing roller 39, when a developing bias, that is, an AC bias superimposed with a predetermined DC bias is applied, the toner on the developing roller 39 flies toward the drum 11. As a result, a toner image is developed on the surface of each drum 11.

  A stay 42 is provided at the lower portion of the housing 23. The stay 42 is made of a heat conductive material (for example, aluminum) and absorbs the heat of the developer (carrier and toner) accommodated in the bottom wall 26 from the heat absorbing portion 43, so that a fan (not shown). It is configured to dissipate heat from the bottom wall duct 44 by air from the bottom.

(Heat transfer part)
The developing unit 17 rotates and drives the mixers 29 and 30 to uniformize the developer (toner and carrier) and maintain a constant amount of developer to be supplied to the drum 11.
When the mixers 29 and 30 are driven to rotate, frictional heat is generated between the developer and the developer, and the developer can be heated to become a heat source, causing the developer itself to be deteriorated by heat and thus causing a reduction in image quality. There is a fear.
In the developing unit 17, in order to cope with such a problem, the peripheral wall ducts 27 and 28 and the bottom wall duct 44 are provided in the peripheral wall 25 and the stay 42, respectively. The unit 17 is cooled.

  However, it is difficult to obtain a sufficient cooling effect especially when the image forming speed is increased only by the configuration in which air is cooled by such a duct, and an excessive temperature rise of the developing unit 17 may not be suppressed.

  Therefore, in the present embodiment, as shown in FIG. 2, the heat transfer portion 45 is interposed between the developing unit 17 and the metal side wall 49 provided on the main body side to be connected (illustrated). However, the heat transfer section 45 is provided so as to extend over the entire length of the developing unit 17), and transfers the heat derived from the developing unit 17 to the metal side wall 49, thereby making the developing unit 17 more efficient. It is configured to cool well (that is, heat derived from the developing unit 17 is transmitted to the main body 2 side).

FIG. 3 shows a side view of the heat transfer unit 45. As shown in FIG. 3, the heat transfer unit 45 includes a heat conducting member 46 and a pressure contact mechanism 47. The surface is covered with the heat conducting member 46.
The heat conducting member 46 is made of, for example, an aluminum foil that is easily plastically deformed and has good heat conductivity. As shown in FIGS. 2 and 3, the peripheral wall 48 (this embodiment) of the developing unit 17 is used. The first contact portion 46a that can come into surface contact with the bottom of the stay 42 and the second contact portion 46b that can come into surface contact with the metal side wall 49 of the main body 2 are connected in series.
The pressure contact mechanism 47 is made of an elastic member such as sponge, for example. As shown in FIG. 2, the first contact portion 46 a and the second contact portion 46 b of the heat conducting member 46 are respectively connected to the developing unit 17. The peripheral wall 48 and the metal side wall 49 of the main body 2 can be pressed against each other.

The heat transfer portion 45 that can come into surface contact with the peripheral wall portion 48 of the developing unit 17 and the metal side wall 49 of the main body 2 is more heat resistant than the metal plate spring in the conventional image forming apparatus that makes line contact with the detachable unit. The conduction efficiency is very high, and heat derived from the developing unit can be quickly transferred to the image forming apparatus main body.
In addition, the heat transfer unit 45 includes a pressure contact mechanism 47 that presses the first contact portion 46a and the second contact portion 46b against the peripheral wall portion 48 of the developing unit and the metal side wall 49 of the image forming apparatus main body. Even if the distance between the peripheral wall portion 48 of the unit and the metal side wall 49 of the image forming apparatus main body is slightly different from the reference dimension, the elastic restoring force of the pressure contact mechanism 47 causes the first heat transfer portion 45 to The first contact portion 46a and the second contact portion 46b can be reliably brought into surface contact with the peripheral wall portion 48 of the detachable unit and the metal side wall 49 of the image forming apparatus main body, respectively.
Therefore, according to the image forming apparatus of the present invention, it is possible to cool the detachable unit containing the heat source very efficiently by the action of the heat transfer section 45 as compared with the conventional image forming apparatus. The excessive temperature rise can be suppressed more reliably.

In particular, when an aluminum foil is used as the heat conducting member 46 and a sponge is used as the pressure contact mechanism 47, the heat transfer portion 45 has a very simple configuration in which the outer peripheral surface of the sponge is covered with the aluminum foil. Therefore, the heat transfer unit 45 does not significantly increase the manufacturing cost of the image forming apparatus of the present invention.
Further, since a sponge is used as the pressure contact mechanism 47, it is easy to set the pressing force to be smaller than that of a metal plate spring or the like in the conventional image forming apparatus. As a result, the heat transfer portion 45 is connected to the peripheral wall portion 48 of the developing unit 17. And the metal side wall 49 of the main body 2 can be installed more easily.

[Another embodiment]
The present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the claims.
[1] For example, as shown in FIG. 4, the pressure contact mechanism 47 in the above-described embodiment may be configured by a spring 50.
[2] In the above-described embodiment, the configuration in which the heat transfer unit 45 is applied to the developing unit 17 as the detachable unit is described. However, the detachable unit can be detached from the main body of the image forming apparatus. The heat transfer unit 45 may be applied to the optical unit 10.
[3] In the above-described embodiment, an example in which the image forming apparatus is embodied in the multifunction machine 1 is shown. However, the image forming apparatus of the present invention is naturally applied to a copying machine, a printer, a facsimile, a scanner, and the like. Applicable.

1 is a diagram schematically illustrating the structure of a multifunction peripheral as an example of an image forming apparatus according to the present invention. FIG. 3 is a longitudinal sectional view showing a state in which the developing unit in the image forming apparatus of the present invention is connected to a metal side wall provided on the main body side via a heat transfer unit. Side view of heat transfer section in image forming apparatus of the present invention The side view of another form of the heat-transfer part in the image forming apparatus of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunctional device 2 Apparatus main body 3 Paper feed part 4 Cassette 5 Paper conveyance part 6 Paper feed part 7 Registration roller 8 Image formation part 9 Transfer part 10 Optical unit 11 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 12 Fixing part 13 Discharge / branch part 14 Paper receiving tray 15 Duplex printing unit 16 Charger 17 Developing unit 18 Cleaning part 19 Intermediate transfer roller 20 Toner container 21 Hopper 22 Intermediate transfer belt 23 Housing 24 Opening 25 Perimeter wall 26 Bottom wall 27 Perimeter wall Duct 28 Perimeter wall duct 29 Stirring mixer 30 Paddle mixer 31 Shaft 32 Shaft 33 Pumping roller 34 Shaft 35 Magnetic brush roller (magnetic roller)
36 Shaft 37 Brush side sleeve 38 Ear cutting blade 39 Developing roller 40 Shaft 41 Developing side sleeve 42 Stay 43 Heat absorbing portion 44 Bottom wall duct 45 Heat transfer portion 46 Heat conducting member 46a First contact portion 46b Second contact portion 47 Pressure contact mechanism 48 Peripheral wall 49 Metal side wall 50 Spring

Claims (2)

An image forming apparatus including a heat source and a detachable unit that is detachable from the main body of the image forming apparatus, and a heat transfer unit that can transmit heat derived from the detachable unit to the main body,
A heat conducting member in which the heat transfer part is continuously connected in series with a first contact part capable of being in surface contact with the peripheral wall part of the detachable unit and a second contact part capable of being in surface contact with the metal side wall of the main body; An image forming apparatus comprising: a pressing mechanism that presses the first contact portion and the second contact portion against a peripheral wall portion of the detachable unit and a metal side wall of the main body, respectively.   The aluminum foil is used as the heat conducting member, a sponge is used as the pressure contact mechanism, and the heat transfer portion is configured to cover the outer peripheral surface of the sponge with the aluminum foil. The image forming apparatus according to 1.

Images