JP2006145727A - Cooling system and image forming apparatus mounting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To fully cool a rotary body without heat generation at its shaft part nor stay of heated air at an upper part, in the roller-shaped rotary body provided to equipment. <P>SOLUTION: This cooling system 40 is provided around the development unit 30 of an image formation part 20 of an image forming apparatus 1 which is the equipment. A first blowing fan 41 on the front side of a roller and a first blowing duct 42 for blowing the air to the shaft part 31a in the front side in the axial direction of a development roller 31 being the roller-shaped rotary body. A second blowing fan 43 which blows the air to the shaft part 31a on the rear side of the roller and a second blowing duct 44 in rear side in the axial direction of the development roller 31. An exhaust duct 45 which exhausts the heated air around the development unit 30 to the outside of the image forming apparatus 1 in the upper part of the development unit 30. Thus, the air is surely circulated near the shaft part 31a and stay of the heated air in the upper part of the development unit 30 is prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shaft portion of a roller-shaped rotating body provided in an apparatus and a cooling device used for cooling the periphery of the rotating body. The present invention also relates to an image forming apparatus equipped with this cooling device.

  In an image forming apparatus represented by a copier or a printer, a heat source is built in at least one roller of a roller pair forming a nip, and a sheet carrying an unfixed toner image in the nip of the roller pair heated by the heat source A heat roller fixing method is widely used in which toner is fixed to a sheet by inserting the toner. However, since heat easily accumulates inside the image forming apparatus, there is a concern that an internal temperature rise resulting from this will hinder the operation of the apparatus.

On the other hand, in addition to the heat roller of the fixing unit, the image forming apparatus is provided with various components related to the temperature rise inside the apparatus, such as a driving device such as a motor, an electrical component, and a sliding part of the roller. Yes. Of these, the temperature rise around the developing device that supplies toner to the image carrier is also a serious problem. When the temperature around the developing device rises, the toner in the developing device melts and fluidity deteriorates, and there is a high possibility that the thin layer formation by the toner on the surface of the developing roller will be disturbed. As a result, the toner image on the surface of the image carrier is adversely affected, and the image formed on the paper may be defective. In order to solve such problems, Patent Documents 1 to 3 show examples of cooling devices proposed for avoiding a temperature rise around the developing device.
Japanese Patent Laid-Open No. 11-218897 (page 3-5, FIGS. 1 and 4) JP 2000-98858 A (page 3-4, FIG. 1) JP 2003-76253 A (page 4-5, FIG. 1-3)

  With respect to a roller-shaped rotating body such as a developing roller of a developing device, a portion where the temperature is likely to rise is mainly its shaft portion. There is a high possibility that friction is generated between the shaft portion and a holding member such as a bearing that supports the shaft portion, and the entire rotating body is heated therefrom. Moreover, since the air with heat rises, it becomes easy to stay just above the rotating body and the frame surrounding the rotating body.

  In each of the image forming apparatuses described in Patent Documents 1 to 3, air is circulated substantially in the paper supply direction to cool the inside. However, for the developing device, it is desirable that air be surely circulates in the vicinity of the shaft portion of the developing roller as described above. Therefore, the image forming apparatus of the above-mentioned patent document has a sufficient cooling effect at this location. It may not be obtained. Similarly, air does not necessarily circulate thereabove even above the developing unit, and there is a possibility that air with heat may stay at this location. Therefore, unless a strict flow path design is adopted so that heated air does not stay in the vicinity of the shaft portion of the developing roller and above the developing device, the cooling efficiency deteriorates and the temperature of the developing device rises and the image is increased. The possibility of having a great adverse effect on the formation is increased.

  The present invention has been made in view of the above points, and the shaft portion does not generate heat with respect to the roller-shaped rotating body provided in the device, or the heated air does not stay in the upper portion. An object of the present invention is to provide a cooling device capable of sufficiently cooling a rotating body. It is another object of the present invention to provide an image forming apparatus equipped with such a cooling device.

  In order to solve the above-described problems, the present invention provides a blowing fan that blows air from one or both of the axial directions toward the vicinity of a shaft portion of a rotating body with respect to a roller-shaped rotating body provided in an apparatus. And an exhaust duct that is provided above the rotating body and releases heat around the rotating body to the outside of the device.

  The exhaust duct is provided with an exhaust fan that forcibly generates an air flow.

  In the present invention, in the developing device of the image forming apparatus, the cooling device is mounted on a developing roller that is a rotating body provided to supply toner to the image carrier.

  According to the configuration of the present invention, a blowing fan that blows air from one or both of the axial directions toward the vicinity of the shaft portion of the rotating body with respect to the roller-shaped rotating body provided in the device, and the rotating body Since it is provided with an exhaust duct that is provided above and dissipates the heat around the rotating body to the outside of the equipment, air can be reliably circulated in the vicinity of the shaft portion of the rotating body, and the heat above the rotating body It is possible to prevent the retention of air having Therefore, it is possible to sufficiently cool the rotating body and maintain a stable operating state of the device.

  In the cooling device having the above configuration, the exhaust duct is provided with an exhaust fan that forcibly generates an air flow, so that air can be discharged more smoothly above the rotating body. Thereby, since it becomes possible to improve the cooling efficiency of a rotary body and its periphery, a much more reliable cooling device can be obtained.

  In the present invention, in the developing device of the image forming apparatus, the cooling device is mounted on the developing roller which is a rotating body provided for supplying toner to the image carrier. It is possible to blow air directly in the vicinity of the part, and to prevent stagnation of heated air above the developing unit. Therefore, it is possible to obtain a highly reliable image forming apparatus capable of sufficiently cooling the developing roller and capable of continuing stable image formation without causing image defects.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. Here, an image forming apparatus is taken as an example of equipment, and the cooling apparatus according to the present embodiment is used to cool a developing device that supplies toner to an image carrier.

  First, the image output operation of the image forming apparatus equipped with the cooling device of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is a schematic vertical sectional front view of an image forming apparatus. A solid line arrow in the drawing indicates a sheet conveyance path and a conveyance direction.

  In FIG. 1, a cassette type paper feed unit 3 is disposed at the bottom of the main body 2 of the image forming apparatus 1. In the cassette type paper feeding section 3, paper P such as cut paper before printing is stacked and stored, and the paper P is separated and sent out one by one. The cassette type paper feed unit 3 includes a three-stage paper cassette 4. The paper feed cassette 4 can be pulled out by sliding to the front side with respect to the main body 2.

  A manual paper feeder 5 is provided outside the upper right side of the main body 2. On the manual sheet feeding unit 5, paper P having a size that is not in the cassette type sheet feeding unit 3 or a sheet to be fed one by one such as an OHP sheet is placed.

  The image forming apparatus 1 includes a paper transport unit 6 therein. The sheet conveyance unit 6 is located on the right side in the sheet feeding direction in terms of the cassette type sheet feeding unit 3, and is located on the left side in terms of the manual sheet feeding unit 5. The paper P sent out from the cassette type paper feed unit 3 is conveyed vertically upward along the side surface of the main body 2 by the paper transport unit 6, and the paper P sent out from the manual paper feed unit 5 is transported horizontally, and will be described later. Part 10 is reached.

  A registration roller 7 is provided on the downstream side in the paper conveyance direction of the paper conveyance unit 6 and immediately upstream of the transfer unit 10. The registration roller 7 feeds the paper P toward the transfer unit 10 in synchronization with a toner image formed by the image forming unit 20 described later while correcting the oblique feeding of the paper P.

  A document feeding portion 8 is provided on the upper surface of the main body 2 of the image forming apparatus 1, and an optical portion 9 is provided below the document feeding portion 8. When a user copies a document, a document on which an image such as a character, a figure, or a pattern is drawn is loaded on the document feeding unit 8. The document feeding unit 8 separates the documents one by one and feeds them, and the optical unit 9 reads the image data.

  An image forming unit 20 and a transfer unit 10 are provided on the downstream side of the registration roller 7 in the sheet conveying direction and below the optical unit 9. In the image forming unit 20, an electrostatic latent image of a document image is formed on the surface of the photosensitive drum 21 that is an image carrier based on the image data read by the optical unit 9. A toner image is formed from the electrostatic latent image by the developing device 30, and the toner image is transferred by the transfer unit 10 to the pre-printing paper P sent in synchronization by the registration roller 7.

  A fixing unit 11 is provided on the downstream side of the transfer unit 10. The paper P carrying the unfixed toner image in the transfer unit 10 is sent to the fixing unit 11 where the toner image is fixed by the heat roller.

  A discharge / branch unit 12 is provided on the downstream side of the fixing unit 11 and in the vicinity of the left side surface of the main body 2. The sheet P discharged from the fixing unit 11 is discharged from the discharge / branch unit 12 to a sheet receiving tray outside the apparatus when duplex printing is not performed.

  A duplex printing unit 13 is provided below the portion from the image forming unit 20 to the discharge / branch unit 12 and above the cassette type sheet feeding unit 3. When performing duplex printing, the paper P discharged from the fixing unit 11 is sent to the duplex printing unit 13 through the discharge / branch unit 12. The paper P sent to the duplex printing unit 13 is subsequently switched in the feeding direction and sent again to the transfer unit 10 via the paper transport unit 6 and the registration roller 7.

  In such an image forming apparatus 1, the cooling device of the present invention is provided around the developing device 30 provided in the image forming unit 20.

  Next, the detailed configuration of the cooling device will be described with reference to FIGS. 2 to 4 in addition to FIG. FIG. 2 is a top view of a model horizontal cross section around the image forming unit and the fixing unit, FIG. 3 is a right side view of the model vertical cross section, and FIG. 4 is a perspective view. In FIG. 3, drawing of the fixing unit 11 is omitted, and in FIG. 4, drawing of the exterior frame of the main body 2 and other components unnecessary for explanation is omitted. The lower side in FIG. 2 is the front side of the image forming apparatus 1 and the left side in FIG. Moreover, in FIGS. 2-4, the white arrow in a figure shows the direction through which air flows.

  As shown in FIGS. 1 and 2, the image forming unit 20 is provided with a photosensitive drum 21 that is an image carrier. Around the photosensitive drum 21, a developing device 30, a cleaning device 22, and the like. Is provided.

  The photosensitive drum 21 includes a conductive roller-like substrate made of aluminum or the like, and a photosensitive layer provided on the outside thereof. The photosensitive layer is provided with amorphous silicon which is an inorganic photoconductive material by vacuum deposition or the like. The photosensitive drum 21 is rotated by a driving device (not shown) so that the peripheral speed thereof is the same as the paper conveyance speed (for example, 175 mm / sec).

  As shown in FIGS. 1 and 2, the developing device 30 is provided with a developing roller 31 that is a roller-shaped rotating body in the vicinity of the photosensitive drum 21. The developing roller 31 is supported by the housing 32 via a bearing (not shown). The developing roller 31 is a non-contact type of the photosensitive member, and a bias having the same polarity as the charging polarity of the photosensitive drum 21 is applied. The developing roller 31 charges the toner, which is a developer, and causes it to fly to the electrostatic latent image on the surface of the photosensitive drum 21 to develop the electrostatic latent image. As the toner, a magnetic or non-magnetic one-component toner or a two-component toner obtained by mixing a magnetic carrier and an insulating toner is used. The developing roller may be a photoreceptor contact type.

  The cleaning device 22 transfers the toner image formed on the surface of the photosensitive drum 21 onto the paper P, and then removes the toner remaining on the surface of the photosensitive drum 21 to perform cleaning. The toner removed from the surface of the photosensitive drum 21 is collected in the housing of the cleaning device 22 and then conveyed to the outside.

  As shown in FIGS. 2 to 4, a cooling device 40 is provided around the developing device 30 of the image forming unit 20. The cooling device 40 includes a first blowing fan 41, a first blowing duct 42, a second blowing fan 43, a second blowing duct 44, an exhaust duct 45, and an exhaust fan 46.

  The first blowing fan 41 is an axial fan, and is fixed inside the exterior frame 2 a on the front side of the main body 2 of the image forming apparatus 1 as shown in FIGS. 2 and 3. The first blowing fan 41 is located immediately in front of the developing roller 31 in the axial direction. The first blowing fan 41 introduces air into the main body 2 from the front of the main body 2 through the opening 2b provided in the exterior frame 2a. A first blowing duct 42 is provided on the downstream side of the first blowing fan 41 in the air movement direction and extends straight up to just before the shaft portion 31 a of the developing roller 31. Therefore, the air introduced from the front of the main body 2 by the first blowing fan 41 can be blown to the vicinity of the shaft portion 31 a on the front side of the developing roller 31.

  The second blowing fan 43 is an axial fan, and is fixed inside the exterior frame 2a on the rear side of the side surface of the main body 2, as shown in FIG. The second blowing fan 43 introduces air into the main body 2 from the right side of the main body 2 through the opening 2c provided in the exterior frame 2a. A second blowing duct 44 is provided on the downstream side of the second blowing fan 43 in the air movement direction. The second blowing duct 44 extends in the lateral direction from the vicinity of the exterior frame 2a on the side surface of the main body 2 so as to approach the developing device 30, bends at a right angle in the axial direction rearward of the developing roller 31, and the duct outlet 44a develops. It faces the roller 31. Therefore, the air introduced from the right side of the main body 2 by the second blowing fan 43 can be blown to the vicinity of the shaft portion 31 a on the rear side of the developing roller 31.

  As shown in FIGS. 2 to 4, the exhaust duct 45 is disposed at a position from above the developing device 30 to the rear part of the main body 2. The exhaust duct 45 includes an intake port 45 a having a length substantially the same as the axial length of the developing device 30 at a location above the developing device 30. The air inlet 45a is positioned downward, that is, toward the developing device 30 and just above the housing 32 of the developing device 30 in order to easily release the heat around the developing device 30. The exhaust duct 45 is folded downstream in the paper supply direction along the internal frame 2d at the rear of the developing device 30, passes through the internal frame 2d in the vicinity of the fixing unit 11, and continues toward the back side of the main body 2.

  As shown in FIG. 2, two exhaust fans 46, which are axial fans, are arranged horizontally at the downstream end of the exhaust duct 45. These exhaust fans 46 forcibly generate an air flow in the exhaust duct 45, and the air in the exhaust duct 45 is passed through the opening 2 e provided in the exterior frame 2 a on the back side of the main body 2. Discharge to the outside. Therefore, the air having the heat around the developing device 30 can be released to the outside of the image forming apparatus 1 by the exhaust fan 46.

  Next, the influence on the temperature change around the developing roller 31 when an experiment is performed using the cooling device 40 having the above configuration will be described with reference to FIG. FIG. 5 is a table showing the influence of the presence or absence of the blowing fan and the exhaust fan on the temperature change before and after the developing roller. At this time, the photosensitive drum 21 is provided with an amorphous silicon photosensitive member, and the developing unit 30 is of a magnetic one-component toner jumping type (photosensitive member non-contact type). The first blowing fan 41 and the second blowing fan 43 both have a diameter of 40 mm, and the two exhaust fans 46 both have a diameter of 80 mm. The temperature data shown in FIG. 5 shows the temperature rise from the start of printing to the end of printing on the front side and the back side in the axial direction of the developing roller 31 when two-sided copies of A4 size paper P are continuously printed. Show.

  According to FIG. 5, when only the first and second blowing fans (B in the figure) are provided (B in the figure) when the blowing fan and the exhaust fan are not provided at all (A in the figure), the developing roller 31. It can be seen that the temperature rise is small on both the front side and the rear side. In this way, the first blowing fan 41 that blows air toward the vicinity of the shaft portion 31a to the developing roller 31 that is a roller-shaped rotating body provided in the image forming apparatus 1 that is a device, And the second blowing fan 43 and the exhaust duct 45 that is provided above the developing roller 31 and releases the peripheral heat to the outside of the image forming apparatus 1, thereby allowing air to flow reliably in the vicinity of the shaft portion 31 a. In addition, since it is possible to prevent stagnation of heated air above the developing roller 31, the developing roller 31 can be sufficiently cooled. Accordingly, it is possible to maintain a stable operation state of the image forming apparatus 1.

  Subsequently, according to FIG. 5, in contrast to the case where only the blowing fan is provided (B in the figure), an exhaust fan is additionally provided (C in the figure), so that the front side and the rear side of the developing roller 31 are further provided. In both cases, it can be seen that the temperature rise is small. In this manner, the exhaust duct 45 includes the exhaust fan 46 that forcibly generates an air flow, so that air can be discharged more smoothly above the developing roller 31. The surrounding cooling efficiency can be increased. Therefore, the cooling device 40 with higher reliability can be obtained.

  In addition, since the cooling device 40 is mounted in the developing device 30 of the image forming apparatus 1, the highly reliable image forming apparatus 1 capable of continuing stable image formation without causing image defects is provided. Obtainable.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  INDUSTRIAL APPLICABILITY The present invention can be used in all devices having a roller-shaped rotating body whose shaft is held by a bearing or the like.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with a cooling device according to an embodiment of the present invention. FIG. 2 is a partial horizontal cross-sectional top view of the periphery of an image forming unit and a fixing unit. FIG. 4 is a right side view of a model vertical cross section around the image forming unit and the fixing unit. FIG. 3 is a perspective view around an image forming unit and a fixing unit. 6 is a table showing the effect of the presence or absence of a blowing fan and an exhaust fan on temperature changes before and after the developing roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body 2a Exterior frame 2d Internal frame 20 Image forming part 21 Photosensitive drum 30 Developing part 31 Developing roller 31a Shaft part 40 Cooling device 41 First blowing fan 42 First blowing duct 43 Second Blowing fan 44 Second blowing duct 45 Exhaust duct 46 Exhaust fan

Claims (3)

  A blowing fan for blowing air from one or both of the axial directions of the roller-shaped rotating body provided in the device toward the vicinity of the shaft of the rotating body, and a rotating body provided above the rotating body. A cooling device comprising: an exhaust duct for releasing ambient heat to the outside of the device.   The cooling device according to claim 1, wherein the exhaust duct includes an exhaust fan that forcibly generates an airflow.   3. An image forming apparatus comprising: a developing device, wherein the cooling device according to claim 1 is mounted on a developing roller that is a rotating body provided to supply toner to the image carrier.

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