JP4397034B2 - Image forming apparatus cooling apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a cooling device and an image forming apparatus of an image forming apparatus, and in particular, an image forming unit that forms a toner image, an intermediate transfer belt that carries a toner image intermediately transferred from a photoreceptor, and an intermediate transfer belt Secondary transfer roller for transferring the toner image to the transfer material, a fixing unit for thermally fixing the toner image on the transfer material, a paper discharge unit for discharging the transfer material to the outside of the apparatus, and the transfer material after fixing The present invention relates to an image forming apparatus including a duplex unit that transports the image to the image forming unit again for duplex printing, and a cooling device used therefor.

  Conventionally, an image forming apparatus that forms an image on a transfer material by an electrophotographic process, particularly a high-speed color copier equipped with a plurality of drums, has an important cooling technique due to an increase in the heat generation part and a higher density in the apparatus. It has become a challenge. In particular, the fixing unit rises to around 20 ° C., and conversely, since the toner allowable upper limit temperature of the image forming unit is as low as 50 ° C., it is indispensable to block the heat between the fixing unit and the image forming unit and to cool it. .

  As shown in FIG. 4, such an image forming apparatus includes an image forming unit 1 including a photosensitive drum 18, a developing roller 19, and the like, an intermediate transfer unit 2 including an intermediate transfer belt 15, a registration roller 14, and the like. A secondary transfer unit 4 including a paper feed unit 3, a secondary transfer roller 17, a counter roller 16, and the like, a duplex unit 5 that reverses a material to be transferred such as transfer paper when performing duplex printing, a conveyance belt 6, and a fixing unit 7, a paper discharge unit 8 including a reversing path, a writing unit 9, a reading unit 10, a shielding plate 11 including a heat pipe for shielding heat, a radiation fin 12 for releasing heat from the shielding plate, a duct 13 and the like. ing.

  This image forming apparatus is a color copying machine on which four photosensitive drums 18 and an intermediate transfer belt 15 are mounted. The toner image formed in the image forming unit 1 is transferred from the photosensitive drum 18 to the intermediate transfer belt 15 as an intermediate transfer. Thereafter, the toner image is transferred onto the transfer material by the secondary transfer roller 17. Further, the transfer paper is transported on a transport belt, the toner image is thermally fixed by the fixing unit 7, and is discharged from the paper discharge unit 8.

  Further, the gap between the fixing unit 7 serving as a heat source and the image forming unit 1 that requires cooling is small, and a shielding plate 11 is provided in the gap to prevent heat from entering the image forming unit 1. Thus, the heat released from the fixing is carried to the heat radiating fins 12 and discharged to the outside by the combination of the duct 13 and the cooling fan.

Conventionally, the following techniques have been proposed in relation to such techniques. Japanese Patent Application Laid-Open No. 2004-228561 describes a fan that controls driving of fans (an outside air introduction fan and an exhaust fan) that cools the inside of the main body in accordance with a printing mode including a double-sided printing mode and a single-sided printing mode. Japanese Patent Application Laid-Open No. H10-228707 describes a cooling fan that cools the recording sheet in the vicinity of the duplex unit. Japanese Patent Application Laid-Open No. 2003-228561 describes an apparatus that includes an exhaust unit that introduces outside air from an intake fan, cools the periphery of the developing unit, and discharges the outside from the exhaust fan, and an exhaust unit that cools the fixing unit. Japanese Patent Application Laid-Open No. 2004-228561 describes that the rotational speed of the exhaust fan is higher in the double-sided printing mode than in the single-sided mode. Patent Document 5 describes a shutter having a variable opening efficiency and a cooling fan that rotates and stops or reduces the rotational speed during standby.
JP-A-10-207326 JP 2002-304107 A JP-A-8-220952 JP 2000-019931 A JP 2003-291458 A

  However, with limited space and cost, it is very difficult to completely shut out the heat of the fixing unit and eliminate the influence on the image forming unit, which causes problems such as color misregistration and toner fixation. End up. These problems are particularly noticeable during duplex printing.

  That is, at the time of double-sided printing, the transfer material heated at the fixing unit passes through the duplex unit and again contacts the intermediate transfer belt at the secondary transfer unit. The temperature will rise. When the intermediate transfer belt reaches a certain temperature or more, the belt is stretched and the toner on the intermediate transfer bell is deformed, thereby causing an image defect. In addition, heat is transmitted to the drum, which is a required cooling unit that is in contact with the intermediate transfer belt, and also to the developing unit, and toner sticking is likely to occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling device and an image forming apparatus for an image forming apparatus capable of efficiently discharging heat in the apparatus and performing good image formation.

The invention of claim 1, the cooling device of the image forming apparatus, the cooling of the image forming apparatus comprising a fixing unit for thermally fixing a toner image on the transfer material, and a discharge unit for discharging the transfer material out of the apparatus A device,
And the exhaust heat fan provided downstream in the discharge direction than the sheet discharge unit,
Disposed below the position of the image forming apparatus, the blowing fan blowing air to the duplex unit and the transfer material is operated in the double-sided drive in which the image forming apparatus performs image formation on both sides of the transfer material,
A first air passage formed between the paper discharge unit and the fixing unit of the image forming apparatus, and a front side plate and a rear side plate constituting a housing of the image forming apparatus, and the blowing fan. in flow generated airflow, a pre-Symbol second air flow path joins the first air channel,
Furthermore, fan drive control means for controlling the operation of the exhaust heat fan and the blowing fan, and a drive unit for the exhaust heat fan,
A plurality of the exhaust heat fans are arranged close to the front side plate and the rear side plate, respectively, and the drive unit is provided on the rear side plate side.
The fan drive control means changes the number of operating heat exhaust fans according to the temperature around the image forming means of the image forming apparatus, and is generated from the drive unit provided on the rear side plate side. In consideration of the influence of heat, when one of the exhaust heat fans is stopped and the number of operating the exhaust heat fans is changed, control is performed to stop the exhaust heat fan arranged on the front side plate side. And

The invention according to claim 2, wherein the cooling device of the image forming apparatus of claim 1, in order to enhance the cooling effect of the rear plate, the rear plate side of the exhaust heat the air volume of the fan front side plate of the exhaust heat and characterized by being larger than the air volume of the fan.

According to a third aspect of the present invention, there is provided an image forming portion for forming a toner image, an intermediate transfer belt for carrying a toner image intermediately transferred from the photosensitive member, and a toner image on the intermediate transfer belt for transferring a toner image onto a transfer material. Next transfer roller, fixing unit that thermally fixes the toner image on the transfer material, paper discharge unit that discharges the transfer material to the outside of the machine, and image transfer unit side again after fixing the transfer material for duplex printing in the image forming apparatus having a duplex unit for conveying the, in which a cooling apparatus according to claim 1 or 2.

According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect , the image forming unit is a tandem type color image forming apparatus provided with a plurality of color image forming means.

According to the present invention, when the number of exhaust heat fans to be operated is changed , the exhaust heat fan disposed on the front side plate side, not the rear side plate side where the cooling effect is required due to the influence of heat generated from the drive unit. By performing the control to stop, the heat in the apparatus can be efficiently discharged and good image formation can be performed.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

1 to 4 show an embodiment of an image forming apparatus according to the present invention. 1 is a sectional view showing a structure of an image forming apparatus according to an embodiment of the present invention, FIG 2 is a side arrangement view from i i Direction in FIG. 1 showing the arrangement of an image forming apparatus according to an embodiment of the present invention 3 is a bottom plan view from the direction iii in FIG. 1 showing the configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a block diagram showing the control system of the image forming apparatus according to the embodiment of the present invention. It is.

  In this example, the image forming unit 1, the intermediate transfer unit 2, the paper feeding unit 3, the secondary transfer unit 4, the duplex unit 5, the conveyance belt 6, the fixing unit 7, the paper discharge unit 8, and the writing unit shown in the conventional example. 9 is the same member as shown in the conventional example, and is arranged at the same position.

In this example, as shown in FIGS. 2 and 3, the image forming apparatus is viewed from a user positioned downstream in the paper discharge direction (right to left in FIG. 3) from the paper discharge unit 8 . Te, a front side plate 21 located on the front side of the image forming apparatus, adjacent respectively to the side plate 22 after positioned on the rear side are provided two heat fans 20 and 20. Further, the respective units 5, 6, 7, 8 in the device, the air flow path is a first air channel between the front Symbol plate 21, 22 that have supported these units 5 to 8 28, 28 Is provided. In addition, the attachment member between each unit 5-8 and the side plates 21 and 22 is not described in the figure. An air flow as indicated by an arrow 23 is generated in the air flow paths 28 and 29, and the heat of the fixing unit 7 and the paper discharge unit 8 through which the transfer material storing heat passes passes before and after these units 7 and 8. Take it away and discharge it outside the machine to reduce the temperature inside the machine.

  Moreover, in this example, the air flow path which crosses the whole apparatus can be provided by providing an inlet port and also an inlet fan in the other side of the surface in which the exhaust heat fans 20 and 20 are provided. While such an air path is formed, it can be relatively easily secured even in an image forming apparatus having a high mounting density, and it is possible to configure a path with less bending and a small pressure loss, and the fan itself has a relatively small static pressure. An inexpensive axial fan can be used. Furthermore, the air flow shown by the arrow 24 can take away the heat of the transfer material and discharge it even under a thermally disadvantageous condition during double-sided / inverted.

  In this example, as shown in FIGS. 2 and 3, a blowing fan 25 is provided below the duplex unit 5 to cool the duplex unit and the material to be transferred passing therethrough. In this example, air flow paths 29 and 29 are provided as second air flow paths that join the air flow generated by the blowing fan 25 to the air flow paths 28 and 28 described above. The air flow paths 29 and 29 merge with the air flow path 29 through the lower side of the double-sided unit 5. The air flow path 29, 29 flows through the air flow indicated by the arrow 26, and even in the case of double-sided printing with severe conditions, the exhaust path for heat of the double-sided unit 5 and the transfer is ensured, and the in-machine atmosphere temperature is efficiently increased. Can be reduced.

  As described above, by generating an air current in the space between the front and back of each unit of the image forming apparatus and the side plate supporting the unit, efficient exhaust heat is generated, and the internal atmosphere temperature can be reduced. It is possible to prevent the occurrence of problems due to temperature rise such as sticking. In addition, the in-machine atmosphere temperature can be efficiently reduced even during duplex printing where conditions for driving the duplex unit are severe.

  Next, drive control of the exhaust heat fans 20 and 20 and the blowing fan 25 in this example will be described. In this example, as shown in FIG. 4, the fan drive control means 30 is connected to the exhaust heat fan 20 and the blowing fan 25, and the drive is controlled. The fan drive control means 30 controls the drive of each fan based on the drive information from the drive unit. Further, if necessary, the thermistor 31 can be provided as temperature detecting means for measuring the temperature of the image forming unit in the image forming apparatus.

  Hereinafter, the control of the fan drive control means 30 will be described. In the present embodiment, an appropriate one of the following control examples is adopted alone or in combination depending on the state of the image forming apparatus.

FIG. 5 is a flowchart showing an example of control by the fan drive control means 30 of this example. It is only two-sided copying operation of the spraying Hun in this example. That is, the fan drive control means 30 obtains information from the drive unit 27 as to whether or not the image forming apparatus is duplex printing (duplex copying), and sets the blowing fan 25 in an operating state only when duplex printing is performed (S11, 12). . When the image forming apparatus performs single-sided printing, the blowing fan 25 is not operated (S13). In other words, the hour blowing fan 25 is provided below the duplex unit 5 and is operated during duplex copying in order to cool the duplex unit and the transfer material passing therethrough. It becomes very effective when passing. In addition, by stopping at times other than double-sided copying, noise is reduced and wasteful power is reduced.

  FIG. 6 is a flowchart showing another control example of the fan drive control means 30. In this example, the fan drive control unit 30 obtains information from the drive unit 27 as to whether the image forming apparatus is in a standby state (waiting for printing), and when it is in a standby state, the exhaust heat fan operates at a reduced rotational speed ( S21, 22), the blowing fan 25 is stopped, and the exhaust heat fan 20 is operated at half speed. Since heat is not generated so much during standby, the exhaust heat fan can operate at a reduced rotational speed. For example, the exhaust heat fan 20 can be operated at half speed by halving the input voltage. Further, in this example, when the apparatus is in operation, the exhaust heat fan 20 and the blowing fan 25 are operated at a normal rotation, and the blowing fan is operated or stopped depending on whether or not the double-sided copy mode is in accordance with the example shown in FIG. You may make it decide.

  According to this example, when the apparatus is on standby, the exhaust heat fan is operated at half speed and the blowing fan is stopped, so that cooling is performed more efficiently, and noise and power can be reduced. Can do.

  FIG. 7 is a flowchart showing another control example of the fan drive control means 30. In the image forming apparatus to which this example is applied, the temperature of the image forming unit 1, for example, the temperature of the cleaning unit is measured by the thermistor 31. When the detected temperature is less than a predetermined constant temperature (α °), the exhaust heat fan is operated at the rotation speed N2 (S31, 32), and when the temperature exceeds the predetermined temperature and the inside of the apparatus needs to be rapidly cooled. Then, the exhaust heat fan is operated at the image speed (rotational speed N1, N1> N2). Therefore, efficient cooling is performed by the temperature around the image formation, noise can be reduced, and power can be reduced.

  FIG. 8 is a flowchart showing another control example of the fan drive control means 30. The image forming apparatus to which this example is applied is provided with a thermistor 31 that measures the temperature of the cleaning unit as in the above-described example. If the temperature is above a certain temperature (α °), both of the exhaust heat fans are operated (S41, 43). If the temperature is lower than the predetermined temperature and there is an allowance for cooling, one exhaust heat fan is stopped. (S42). Therefore, efficient cooling is performed by the temperature around the image formation, noise can be reduced, and electric power can be reduced.

Further, in this example, the fan drive control means 30 stops one exhaust heat fan when the temperature around the image formation is below a certain temperature, but the stopped fan is an exhaust heat fan close to the front plate. The exhaust heat fan on the front plate side cools the front side of the unit, but the exhaust heat fan on the rear plate side also has an influence of heat generated from the drive unit 27 provided on the rear plate in addition to cooling of the rear side of the unit. Yes, more cooling effect is required. Therefore, when the temperature around the image is lowered and one exhaust heat fan is stopped, it is appropriate to stop the front heat exhaust fan, which allows efficient cooling, reducing noise and reducing power consumption. Connected.

  Furthermore, in this example, the air volume of the exhaust heat fan on the rear plate side is made larger than the air volume of the exhaust heat fan on the front plate side. As a means, the number of rotations of the rear plate side exhaust heat fan can be increased, or a fan having a large air volume in specification can be used as the exhaust heat fan on the rear plate side. Thereby, the air volume of the exhaust heat fan on the rear plate side can be made larger than the air volume of the exhaust heat fan on the front side plate, cooling is performed more efficiently, and noise reduction and power reduction can be realized.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along arrow i ii when viewed from the direction of arrow ii in FIG. 1 showing the configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the arrow i i as viewed from the direction of the arrow iii in FIG. 1 showing the configuration of the image forming apparatus according to the embodiment of the present invention. 2 is a block diagram illustrating a control system of the image forming apparatus according to the embodiment of the present invention. FIG. It is a flowchart which shows the fan drive control means control which concerns on the Example of this invention. It is a flowchart which shows the fan drive control means control which concerns on the Example of this invention. It is a flowchart which shows the fan drive control means control which concerns on the Example of this invention. It is a flowchart which shows the fan drive control means control which concerns on the Example of this invention. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus to which the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming part 2 Intermediate transfer unit 3 Paper feed unit 4 Secondary transfer unit 5 Duplex unit 6 Conveyor belt 7 Fixing unit 8 Paper discharge unit 9 Writing unit 10 Reading unit 11 Shielding plate 12 Radiation fin 13 Duct 14 Registration roller 15 Intermediate Transfer belt 16 Opposing roller 17 Secondary transfer roller 18 Photosensitive drum 19 Developing roller 20 Heat exhaust fan 25 Blow fan 27 Drive unit 30 Fan drive control means 31 Thermistor

Claims (4)

A cooling device for an image forming apparatus, comprising: a fixing unit that thermally fixes a toner image on a transfer material; and a paper discharge unit that discharges the transfer material to the outside of the apparatus .
And the exhaust heat fan provided downstream in the discharge direction than the sheet discharge unit,
Disposed below the position of the image forming apparatus, the blowing fan blowing air to the duplex unit and the transfer material is operated in the double-sided drive in which the image forming apparatus performs image formation on both sides of the transfer material,
A first air passage formed between the paper discharge unit and the fixing unit of the image forming apparatus, and a front side plate and a rear side plate constituting a housing of the image forming apparatus, and the blowing fan. in flow generated airflow, a pre-Symbol second air flow path joins the first air channel,
Furthermore, fan drive control means for controlling the operation of the exhaust heat fan and the blowing fan, and a drive unit for the exhaust heat fan,
A plurality of the exhaust heat fans are arranged close to the front side plate and the rear side plate, respectively, and the drive unit is provided on the rear side plate side.
The fan drive control means changes the number of operating exhaust heat fans according to the temperature around the image forming means of the image forming apparatus, and is generated from the drive unit provided on the rear side plate side. Considering the influence of heat, when any of the exhaust heat fans is stopped to change the number of operating the exhaust heat fans, control is performed to stop the exhaust heat fans arranged on the front side plate side. And a cooling device for the image forming apparatus. To increase the cooling effect of the rear plate, the image formation according to claim 1, the air volume of the exhaust heat fan of the rear side plate, characterized by comprising greater than the air volume of the exhaust heat fan of the front side plate Equipment cooling device. An image forming unit for forming a toner image; an intermediate transfer belt for carrying a toner image intermediately transferred from the photosensitive member; a secondary transfer roller for transferring the toner image on the intermediate transfer belt to a transfer material; A fixing unit that heat-fixes the upper toner image, a paper discharge unit that discharges the transferred material to the outside of the machine, and a duplex unit that transports the transferred material to the imaging unit again for duplex printing. in the image forming apparatus, an image forming apparatus comprising the cooling apparatus according to claim 1 or 2. 4. The image forming apparatus according to claim 3 , wherein the image forming unit is a tandem type color image forming apparatus including a plurality of color image forming units.