JP5817375B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile machine, and a digital multi-function machine that combines these functions.

  Many so-called tandem color image forming apparatuses are used as electrophotographic image forming apparatuses. There are an intermediate transfer method and a direct transfer method, all of which are a photoreceptor for forming a toner image of each color such as yellow, magenta, cyan, and black, a charging device disposed around the photosensitive member, and a developing device using toner. The image forming sections including the are arranged side by side by the number of colors. An endless belt that rotates in the vicinity of each image forming unit is provided.

  In the case of the intermediate transfer method, the endless belt is an intermediate transfer belt, and the toner images of the respective colors formed on the photoconductors at the respective image forming units are sequentially transferred onto the surface of the intermediate transfer belt that rotates around the primary transfer. Thus, a full color toner image is formed. The toner is conveyed to a secondary transfer position by the movement of the intermediate transfer belt, where the full-color toner image is secondarily transferred to a sheet as a recording medium, fixed through a fixing device, and discharged.

  In the case of the direct transfer method, the endless belt is a paper conveyance belt, and the toner images of the respective colors formed on the photoconductors in the respective image forming units are adsorbed and conveyed on the rotating paper conveyance belt. A full-color toner image is formed by sequentially superimposing and transferring on a sheet. It is fixed through a fixing device and discharged.

  In such image formation, a photoconductor (generally a photoconductor drum) is heated by applying a high voltage to a charging device and irradiating a laser beam from an exposure device. Heat is transferred to the endless belt. Further, the endless belt may be heated by radiant heat generated by the fixing device.

  In the case of an intermediate transfer type image forming apparatus, the toner image on the intermediate transfer belt is secondarily transferred to a sheet, and then the toner remaining after the second transfer is removed and collected. An intermediate transfer belt cleaner is provided. Therefore, the intermediate transfer belt is rubbed by a cleaning member such as a cleaning blade of the intermediate transfer belt cleaner, and the temperature rises due to the frictional heat.

When the temperature of the endless belt rises, the toner image transferred onto the intermediate transfer belt melts and adheres to the intermediate transfer belt, or is transferred onto the sheet conveyed by being attracted to the conveyance belt. The toner image is melted and the image is disturbed.
In addition, the image forming unit cannot be cooled via the endless belt, the temperature of the developing device having the photosensitive member and the toner stirring member rises, and the surface of the photosensitive member and the toner in the developing device are melted. There was also a risk of hindering image formation.

  In order to solve such a problem, for example, Patent Document 1 and Patent Document 2 disclose a fan for blowing an air current on the surface of the intermediate transfer belt, an exhaust fan, and a ventilation duct on the outer peripheral side of the intermediate transfer belt. There is disclosed an image forming apparatus provided with a cooling mechanism including the above to cool an intermediate transfer belt.

  However, since such a cooling mechanism requires a considerably large space around the intermediate transfer belt, the size of the image forming apparatus is increased, and an airflow is blown on the surface of the intermediate transfer belt to cool it, so that the transfer surface vibrates. As a result, the transferred toner may scatter and transfer defects may occur.

  In order to solve the problem of the space for providing the cooling mechanism, for example, in Patent Document 3, as shown in FIG. 7, a driving roller 52, a tension roller 53, and a secondary transfer inner roller 54 supported by a frame 51 are provided. Therefore, there is proposed an image forming apparatus in which a duct 60 for cooling the intermediate transfer belt 55 is provided in the intermediate transfer unit 50 that spans the intermediate transfer belt 55 as indicated by a virtual line.

  The duct 60 forms a cooling space 61 having a heat intake port 61 a on the back side of the intermediate transfer belt 55 in a region between the tension roller 53 and the secondary transfer inner roller 54 in the intermediate transfer unit 50. The cooling space 61 has a suction side duct 62 and a discharge side duct 63 extending rearward in a substantially V shape from one half and the other half of the intermediate transfer belt 55 in the width direction. A suction port 64 at the end portion of the suction side duct 62 and a discharge port 65 at the end portion of the discharge side duct 63 are respectively provided at one and the other of the central portion in the longitudinal direction along the circumferential rotation direction of the intermediate transfer belt 55 on the surface. ing.

  According to this duct 60, the air flowing in from the suction port 64 flows in the direction of the arrow A in the suction side duct 62, hits the back surface of the intermediate transfer belt facing the heat intake port 61a in the cooling space 61, and cools it. To do. The air flows in the discharge side duct 63 in the direction of arrow B and flows out from the discharge port 65.

  According to such a configuration, since the duct 60 that forms the cooling space 61 for cooling the intermediate transfer belt 55 is provided in the intermediate transfer unit 50, an extra space is provided outside the intermediate transfer belt that is an endless belt. Therefore, it is possible to prevent an increase in the size of the image forming apparatus.

  However, the suction-side duct 62 and the discharge-side duct duct 63 extend obliquely with respect to the back surface of the intermediate transfer belt 55, and air that has flowed into the cooling space 61 from the suction-side duct 62 reaches the back surface of the intermediate transfer belt 55. It will flow like spraying. Therefore, there is a possibility that the transfer surface of the intermediate transfer belt 55 may vibrate, and the problem that the transferred toner scatters and a transfer failure occurs cannot be solved sufficiently.

  The present invention has been made to solve such problems, and prevents an increase in the temperature of an endless belt such as an intermediate transfer belt, thereby eliminating the occurrence of problems such as toner melting while increasing the space. The object is to suppress the enlargement due to the toner, and to eliminate the possibility of causing the toner to scatter by vibrating the endless belt, thereby preventing the occurrence of transfer failure.

In order to achieve the above-described object, the present invention provides an image forming unit including a photosensitive member, a charging device disposed around the photosensitive member, and a developing device that develops toner, and an endless belt that rotates in the vicinity of the image forming unit. An air inflow port on one side of both end portions in the width direction orthogonal to the circumferential rotation direction of the endless belt, and an air outflow port on the other side. A ventilation duct in which the back surface of the endless belt forms one wall surface of the cooling space, and the cooling space of the ventilation duct gradually increases from the air inlet side toward the air outlet side. has become widely, from the air inlet of the air duct to the air outlet through the cooling space, by flowing air to the width direction over the entire width of the back surface along the back surface of the endless belt, That Characterized in that so as to cool the end shaped belt.

According to the present invention, a ventilation duct is provided inside an endless belt such as an intermediate transfer belt, and the air flowing in from the air inlet is formed along the back surface of the endless belt forming one wall surface in the ventilation duct. It flows in the width direction of the endless belt over the entire width of the back surface. At that time, the endless belt is deprived of heat and cooled, and then flows out from the air outlet.
Therefore, the endless belt can be cooled without taking extra space. Moreover, since the cooling air always flows along the back surface of the endless belt, the heat exchange efficiency is good, and air is not blown onto the endless belt, so there is no possibility of vibrating the endless belt. For this reason, there is no fear of transfer failure due to toner scattering or the like.

1 is a schematic diagram illustrating an overall configuration of an embodiment of an image forming apparatus according to the present invention. 2 is a schematic configuration diagram illustrating a configuration example of the image forming unit 1. FIG. FIG. 2 is an enlarged view showing a main part according to the present invention in the image forming apparatus shown in FIG. 1. It is a perspective view of the ventilation duct shown in FIG. FIG. 4 is a perspective view showing a state where the ventilation duct shown in FIG. 3 is mounted in an intermediate transfer belt. FIG. 6 is a plan view showing an example of a state in which the ventilation duct is connected to an intake duct provided in the image forming apparatus main body. FIG. 6 is a perspective view showing a conventional example in which a cooling duct is provided inside an intermediate transfer unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Overall description of image forming apparatus]
FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of an image forming apparatus according to the present invention, and FIG.
The image forming apparatus shown in FIG. 1 includes a main body 100, an image reading unit 110, and a duplex conveyance unit 120.

In the main body 100, four image forming units 1Y, 1M, 1C, and 1 for forming toner images of yellow, magenta, cyan, and black (hereinafter referred to as Y, C, M, and K) as image forming units. It has 1K.
Each of these image forming units 1Y, 1M, 1C, and 1K includes photoreceptor drums 3Y, 3M, 3C, and 3K that are photoreceptors, and a developing unit that develops with a charging device and toner, which will be described later, around each of them. Yes. In order to form each color image on the surface of each photosensitive drum 3Y, 3M, 3C, 3K, each developing unit uses Y toner, M toner, C toner, and K toner of different colors. Have the same configuration. The structure will be described later with reference to FIG.

This image forming apparatus is a tandem type intermediate transfer type color printer, and an intermediate transfer belt 5 that is an endless belt that rotates in the vicinity of an image forming unit includes a secondary transfer counter roller 6 that is a driving roller and a driven roller. 7 with a predetermined tension.
The image forming units 1Y, 1M, 1C, and 1K, which are the above-described image forming portions, are sequentially arranged on the lower surface side of the intermediate transfer belt 5 along the belt traveling direction.
Below the image forming units 1Y, 1M, 1C, and 1K, an image writing unit 8 that exposes and scans the surface of each of the photosensitive drums 3Y, 3M, 3C, and 3K with a laser beam is provided.

Further, primary transfer rollers are disposed at positions facing the image forming units 1Y, 1M, 1C, and 1K with the intermediate transfer belt 5 interposed therebetween, but the illustration is omitted.
A ventilation duct 40 for cooling the intermediate transfer belt 5 is provided on the back side of the upper region of the intermediate transfer belt 5. Details of the ventilation duct 40 will be described later.
Above the intermediate transfer belt 5, toner bottles 9Y, 9M, 9C, and 9K are interchangeably mounted in order to supply each color toner to the developing units of the image forming units.

  On the other hand, the paper 10 as a transfer material to be image-formed is accommodated in two stages of paper feed cassettes 11A and 11B. The paper 10 in each of the paper feeding cassettes 11A and 11B is fed out one by one by one of the pickup rollers 12A and 12B provided on the paper feeding side. The fed sheet 10 is conveyed to the positioning roller pair 13 along a conveyance path indicated by a thin line in FIG. 1 by a plurality of conveyance roller pairs not shown.

  The secondary transfer roller 14 and the secondary transfer counter roller 6 are sent to the secondary transfer position facing each other with the intermediate transfer belt 5 interposed therebetween at a predetermined timing by the positioning roller pair 13. A fixing device 19 is disposed in the transport path above the secondary transfer position, and the paper that has passed through the fixing device 19 is discharged onto the paper discharge tray 22 by the paper discharge transport roller pair 20.

  Although not shown, the image reading unit 110 includes a contact glass and a pressure plate that can be opened and closed or an automatic document feeder (ADF), and below the contact glass, A reading scanning device including a light source, an optical system, and an imaging device such as a CCD is provided.

The double-sided conveyance unit 120 is attached to one side surface of the main body 100, and includes a paper conveyance path indicated by a thin line in FIG. 1, and a reverse roller pair 15 and a plurality of double-sided conveyance roller pairs 16 along the paper conveyance path.
Then, a sheet on which the toner image is transferred onto one surface and fixed through the fixing device 19 is introduced, and the paper is reversed and sent to the positioning roller pair 13. Thereby, the toner image can be transferred to the other side of the paper to form an image.
In this embodiment, the manual feed tray 17 is also attached to the double-sided conveyance unit 120, and the paper 10 set on the manual feed tray 17 is also sent to the positioning roller pair 13 by the conveyance roller pair 18, and the toner image is transferred thereto. To form an image.

An outline of an operation procedure when a color image is formed by the image forming apparatus configured as described above will be described with reference to FIG.
When this image forming apparatus is used as a copying apparatus, when a color original for copying is set in the image reading unit 110 and the start key is pressed, reading of the original is started, and the read color image data is converted into the read color image data. Based on this, a controller (not shown) generates color print data.

When this image forming apparatus is used as a printer, when a print command and a color printing job are received from a host device such as a personal computer connected via a network or the like, the controller generates color print data based thereon. .
In accordance with one of the color print data, the image forming process by each of the image forming units 1Y, 1M, 1C, 1K, the image writing unit 8, and the like is started in order.

  First, the surface of each photosensitive drum 3Y, 3M, 3C, 3K is uniformly charged by each charging device described later, and each surface is exposed according to the image data of each color by optical scanning of the image writing unit 8, An electrostatic latent image is formed on each surface. Each electrostatic latent image is developed with each color toner of each developing unit described later, and yellow, magenta, cyan, and black toner images are respectively formed on the surfaces of the photosensitive drums 3Y, 3M, 3C, and 3K. Sequentially formed.

  The toner images of the respective colors on the photosensitive drums 3Y, 3M, 3C, and 3K are primarily transferred onto the intermediate transfer belt 5 in order by primary transfer roller by an action of a primary transfer roller (not shown) to which a bias voltage is applied. A full-color toner image is formed on 5. The toner image is sent to the secondary transfer position by moving the toner image to the right by the rotation of the intermediate transfer belt 5.

On the other hand, as described above, the paper 10 having a size suitable for the image size of any of the paper feed cassettes 11A and 11B is fed out by the pick-up roller 12A or 12B and sandwiched between the positioning roller pair 13 by a pair of conveying rollers (not shown). Transport and wait until
The pair of positioning rollers 13 sends the paper 10 at a predetermined timing to a secondary transfer position where the secondary transfer roller 14 and the secondary transfer counter roller 6 are opposed to each other with the intermediate transfer belt 5 interposed therebetween.

As a result, the toner image on the intermediate transfer belt 5 is batch-transferred (secondarily transferred) onto the paper 10 by the action of the secondary transfer roller 14 to which a bias voltage is applied.
The sheet 10 on which the full-color toner image has been transferred is conveyed to the fixing device 19, where it is subjected to fixing processing by heating and pressurization, sent out, and discharged onto the sheet discharge tray 22 by the sheet discharge conveyance roller pair 20. .

When forming a monochrome image, the image reading unit 110 reads or generates monochrome print data based on monochrome image data received from the host device, and uses only the black image forming unit 1K as the image forming unit. Then, a black toner image is formed on the surface of the photosensitive drum 3K. It is transferred to the intermediate transfer belt 5 and then transferred to the paper 10.
The transfer material may be any medium that can transfer and fix a toner image, and is also referred to as transfer paper, printing paper, recording paper, printing sheet, recording sheet, and the like in addition to paper.

[Configuration example of image forming unit]
Here, a configuration example of the image forming units 1Y, 1M, 1C, and 1K will be described. Each of these image forming units has the same configuration except for the color of the toner used as described above. An example of the configuration will be described with reference to FIG. 2 as an image forming unit 1 without Y, M, C, and K.
The image forming unit 1 shown in FIG. 2 includes a photoconductor unit 2 and a developing unit 4. These can be attached to and detached from the main body 100 shown in FIG. 1 as an integral unit or as an individual unit.

The photoreceptor unit 2 includes a photoreceptor drum 3, a drum cleaning device 23, a static eliminator (not shown), a charging device 24 that charges the surface of the photoreceptor drum 3, and the like. The photosensitive drum 3 is rotationally driven in a clockwise direction in the drawing by a driving unit (not shown).
The charging device 24 includes a charging roller 25 to which a charging bias is applied in the vicinity of the surface of the photosensitive drum 3. The charging roller 24 rotates and rotates the charging roller counterclockwise so that the surface of the photosensitive drum 3 is unified. Charge like this.

In addition, as the charging device, a device in which a charging brush is brought into contact with the photosensitive member instead of the charging roller may be used. Alternatively, a charger that charges the photosensitive member by a charger method, such as a scorotron charger, may be used.
The surface of the photosensitive drum 3 uniformly charged by the charging device 24 is exposed and scanned by the laser light L emitted from the image writing unit 8 shown in FIG. 1 to carry an electrostatic latent image.

  The developing unit 4 includes, in a housing 4a, a first agent containing portion 27 in which a first conveying screw 26 is disposed, a toner concentration sensor 28 including a magnetic permeability sensor, a second conveying screw 29, a developing roller 30, And a second agent container 32 provided with a doctor blade 31 as a developer regulating member.

  Inside the first agent storage portion 27 and the second agent storage portion 32, a developer (not shown) made of a magnetic carrier and negatively chargeable toner is stored. The first conveying screw 26 is rotationally driven by a driving unit (not shown), and conveys the developer in the first agent storage unit 27 from the near side to the far side in the direction perpendicular to the paper surface. Then, the developer is allowed to enter the second agent accommodating portion 32 through a communication port (not shown) provided in the partition wall 4 b between the first agent accommodating portion 27 and the second agent accommodating portion 32.

  The second conveying screw 29 in the second agent accommodating portion 32 is rotationally driven to convey the developer from the back side to the near side in the drawing. The toner density of the developer being conveyed is detected by a toner density sensor 28 fixed to the bottom of the second agent container 32. Above the second conveying screw 29, a developing roller 30 is disposed in parallel with the second conveying screw 29. The developing roller 30 includes a magnet roller 34 in a developing sleeve 33 formed of a nonmagnetic pipe that is driven to rotate counterclockwise in the drawing.

  Part of the developer conveyed by the second conveying screw 29 is pumped up to the surface of the developing sleeve 33 by the magnetic force of the magnet roller 34. Then, after the layer thickness is regulated by the doctor blade 31 arranged so as to maintain a predetermined gap with the developing sleeve 33, the layer thickness is regulated and conveyed to the developing area facing the photosensitive drum 3. Toner is attached to the electrostatic latent image. By this adhesion, a toner image is formed on the photosensitive drum 3.

  The toner image formed on the photosensitive drum 3 is intermediately transferred to the intermediate transfer belt 5 shown in FIG. Then, the drum cleaning device 23 removes the toner remaining on the surface of the photosensitive drum 3 after the intermediate transfer process. The surface of the photosensitive drum 3 that has been subjected to the cleaning process is neutralized by a neutralizing device (not shown) to prepare for the next image formation.

[Configuration example of ventilation duct]
Next, a configuration example of the ventilation duct 40 will be described with reference to FIGS.
FIG. 3 is an enlarged view showing a main part according to the present invention in the image forming apparatus shown in FIG. The intermediate transfer belt 5 is stretched between a secondary transfer counter roller 6 as a driving roller and a driven roller 7 with a predetermined tension. In FIG. 3, there is a gap between the intermediate transfer belt 5 and the secondary transfer counter roller 6 and the driven roller 7, but in reality, the intermediate transfer belt 5 is stretched over more rollers including tension rollers. Therefore, they are shown schematically in a simplified manner.

On the lower surface side of the intermediate transfer belt 5, the above-described image forming units 1Y, 1M, 1C, and 1K, which are image forming portions, are sequentially arranged along the belt traveling direction.
An intermediate transfer belt cleaner 21 is disposed on the upper surface side downstream of the secondary transfer position where the secondary transfer counter roller 6 and the secondary transfer roller 14 face each other in a region where the intermediate transfer belt 5 rotates. In the intermediate transfer belt cleaner 21, the tip of the cleaning blade 21a abuts on the upper surface of the intermediate transfer belt 5, and the toner remaining on the intermediate transfer belt after the secondary transfer is removed and collected by a mechanism (not shown). .

The ventilation duct 40 is primary-transferred by the photosensitive drums 3Y, 3M, 3C, and 3K of the image forming units 1Y, 1M, 1C, and 1K and a primary transfer roller (not shown) in the region in which the intermediate transfer belt 5 rotates. The intermediate transfer belt 5 is provided close to and opposed to the back surface of the intermediate transfer belt 5 on the upstream side of the position and on the downstream side of the secondary transfer position described above. In this example, the ventilation duct 40 is provided in a region immediately after the intermediate transfer belt 5 passes through the intermediate transfer belt cleaner 21.
The ventilation duct 40 forms a cooling space 41 in which the back surface of the intermediate transfer belt 5 is a wall surface.

4 is a perspective view of the ventilation duct 40, and FIG. 5 is a perspective view showing a state in which the ventilation duct 40 is mounted in the intermediate transfer belt 5. As shown in FIG.
As shown in these drawings, the ventilation duct 40 is provided on one side of both end portions in the width direction (arrow W direction) perpendicular to the circumferential rotation direction of the intermediate transfer belt 5 (arrow F direction shown in FIG. 5). Each has an air inflow port 42 and an air outflow port 43 on the other side, and a cooling space 41 is formed therebetween. The ventilation duct 40 is made of a metal plate or a synthetic resin.

The air inflow port forming portion 42a and the air outflow port forming portion 43a are in the shape of a rectangular tube whose entire circumference is surrounded by the wall surface of the duct, but the cooling space 41 is a flat surface with an open upper surface as clearly shown in FIG. Channel shape. Then, as shown in FIG. 5, the upper surface of the intermediate transfer belt 5 is disposed close to the back surface, so that the back surface forms one wall surface of the cooling space 41.
Further, the cooling space 41 of the ventilation duct 40 has a gradually increasing duct width (width in a direction perpendicular to the air flow) from the air inlet 42 side toward the air outlet 43 side.

  As shown in FIG. 5, the ventilation duct 40 is arranged on the inner side (back side) of the intermediate transfer belt 5 along the width direction (arrow W direction). As a result, the air inlet forming portion 42 a protrudes from one side of the intermediate transfer belt 5, the air outlet forming portion 43 a protrudes from the other side, and the cooling space 41 is within the width of the intermediate transfer belt 5.

  When the ventilation duct 40 is arranged in this manner and air is introduced from the air inlet 42, the air passes through the cooling space 41 to the air outlet 43 along the back surface of the intermediate transfer belt 5 (in parallel). It flows in the width direction indicated by arrow W over the entire width of the back surface. At that time, the air flowing while contacting the back surface of the intermediate transfer belt 5 loses its heat to cool the intermediate transfer belt 5, and the warm air is discharged from the air outlet 43. Since the intermediate transfer belt 5 rotates around the circumference, the intermediate transfer belt 5 sequentially moves on the upper surface of the cooling space 41 and is cooled over the entire length.

  In this way, the air in the cooling space 41 always flows along (in parallel with) the back surface of the intermediate transfer belt 5, so that the heat exchange efficiency is good. Further, since air is not blown onto the intermediate transfer belt 5, there is no possibility of vibrating the intermediate transfer belt 5. For this reason, there is no fear of transfer failure due to toner scattering or the like.

  Further, the air sucked into the ventilation duct 40 flows while taking the heat along the back surface of the intermediate transfer belt 5 in the cooling space 41. Therefore, the air is warmed as it goes to the air outlet 43 side, and the cooling efficiency is lowered. However, a temperature distribution may occur in the intermediate transfer belt 5 due to the difference in cooling efficiency.

  However, in this embodiment, the cooling space 41 of the ventilation duct 40 gradually increases in width from the air inlet 42 side toward the air outlet 43 side. The contact area between the air and the air increases to compensate for the decrease in cooling efficiency. For this reason, it is possible to prevent the temperature distribution from occurring in the width direction region of the intermediate transfer belt 5 due to the difference in cooling efficiency and affect the image quality.

FIG. 6 is a plan view showing a state in which the ventilation duct 40 is connected to an intake side duct provided in the main body of the image forming apparatus.
In this embodiment, an intake duct 45 is provided on the inner surface side of the front cover 101 which is one of the openable and closable exterior covers of the main body 100 (see FIG. 1) of the image forming apparatus. One end portion of the intake side duct 45 is connected to an intake port 46 formed in a side portion of the front cover 101, and a connection portion 45a to the ventilation duct 40 is provided at the other end portion.

  The intermediate transfer belt 5, a secondary transfer counter roller (drive roller) 6 that supports the intermediate transfer belt 5 so as to be rotatable, a driven roller 7, and the like, and a ventilation duct 40 are mounted at predetermined positions in the main body 100 of the image forming apparatus. When the front cover 101 is closed in this state, the connection portion 45a of the intake duct 45 is connected to the air inlet formation portion 42a of the ventilation duct 40 as shown in FIG. Thereby, the air inlet 42 of the ventilation duct 40 and the outside communicate with each other via the intake duct 45 and the intake port 46.

  An exhaust side duct 47 that communicates with the outside may be provided inside the rear part of the main body 100 as indicated by an imaginary line in FIG. 6, and one end thereof may be connected to the air outlet formation part 43 a of the air duct 40. If an intake fan is provided between the intake side duct 45 and the intake port 46 and an exhaust fan is provided between the exhaust side duct 47 and an exhaust port (not shown), sufficient cooling can be achieved. It is possible to inhale air from outside the apparatus and send it to the ventilation duct 40 to reliably discharge the warm air after the intermediate transfer belt 5 is cooled.

  However, only one of the intake fan and the exhaust fan may be provided. Also, if the air outlet 43 of the ventilation duct 40 is opened in the main body 100, the flow of air flowing out from the intake port 46 through the intake side duct 45 and the ventilation duct 40 into the machine by a cooling fan provided there. Will occur. Therefore, it is not essential to provide a dedicated intake fan or exhaust fan.

The intermediate transfer belt 5 includes a secondary transfer counter roller 6, a driven roller 7 and a roller such as a tension roller (not shown), a ventilation duct 40, a frame supporting the intermediate transfer unit, and the like. And can be integrally attached to and detached from the main body 100.
Further, only the ventilation duct 40 may be detachably attached to the intermediate transfer unit.

  In this embodiment, an intake side duct 45 that allows the air inlet 42 of the ventilation duct 40 to communicate with the outside is integrated with the inner surface side of the front cover 101 that is an openable / closable exterior cover provided in the main body 100 of the image forming apparatus. Therefore, when the front cover 101 is opened, the intake side duct 45 is also detached from the ventilation duct 40 and retracted. Therefore, the ventilation duct 40 and the intermediate transfer unit including the ventilation duct 40 can be easily attached to and detached from the main body 100.

Further, the intermediate transfer belt 5 is arranged in the region upstream of the primary transfer position in the traveling direction of the intermediate transfer belt 5 and in the region downstream of the secondary transfer position in the region where the intermediate transfer belt 5 rotates. It is arranged on the back side.
Therefore, after the intermediate transfer belt 5 secondarily transfers the toner image on the surface thereof to the paper, the ventilation duct 40 is formed before the next toner image created by the image forming units 1Y, 1M, 1C, and 1K is primarily transferred. It is sufficiently cooled by the air flowing through it. For this reason, the region reaching the primary transfer position of the intermediate transfer belt 5 is sufficiently cooled, and there is no fear that the transferred toner will melt. Further, the image forming units 1Y, 1M, 1C, and 1K can be cooled by coming into contact with the cooled intermediate transfer belt 5.

  Further, by arranging the ventilation duct 40 in a region immediately after the intermediate transfer belt 5 passes through the intermediate transfer belt cleaner 21, heat generated by friction between the intermediate transfer belt 5 and the cleaning blade can be efficiently cooled. .

  The image forming apparatus according to the present invention is provided with the ventilation duct described above as a cooling means for the intermediate transfer belt, but is not limited to the tandem type intermediate transfer type color printer as shown in FIG. Various image forming apparatuses such as other intermediate transfer type or direct transfer type color printers, monochrome printers, copying machines each equipped with an image reading unit, facsimile machines, and digital multi-function machines combining these functions Also, the present invention can be applied.

In the case of a tandem type direct transfer type image forming apparatus, the endless belt that rotates in the vicinity of the image forming unit is a sheet conveying belt that adsorbs and conveys the sheet on the surface. A ventilation duct as described above may be provided on the back side.

1, 1Y, 1M, 1C, 1K: Image forming unit 2: Photoconductor unit 3, 3Y, 3M, 3C, 3K: Photoconductor drum 4: Developing unit
4a: Development unit housing 4b: Partition wall 5: Intermediate transfer belt
6: Secondary transfer counter roller 7: Driven roller 8: Image writing unit
9Y, 9M, 9C, 9K: Toner bottle 10: Paper
11A, 11B: Paper feed cassette 12A, 12B: Pickup roller
13: Positioning roller pair 14: Secondary transfer roller 15: Reversing roller pair
16: Duplex conveyance roller pair 17: Manual feed tray 18: Conveyance roller pair
19: Fixing device

20: A pair of conveying rollers for paper discharge 21: Intermediate transfer belt cleaner
22: discharge tray 23: drum cleaning device 24: charging device 25: charging roller 26: first conveying screw 27: first agent container 28: toner concentration sensor 29: second conveying screw 30: developing roller 31: doctor blade 32: Second agent container 33: Developing sleeve 34: Magnet roller 40: Ventilation duct 41: Cooling space
42: Air inlet 42a: Air inlet forming part 43a: Air outlet forming part 43: Air outlet 45: Intake side duct 46: Inlet 47: Exhaust side duct 100: Body of image forming apparatus 101: Front cover ( Exterior cover)
110: Image reading unit 120: Double-sided conveyance unit

JP 2007-240703 A JP 2010-145733 A JP 2007-271688 A

Claims (5)

In an image forming apparatus comprising: an image forming unit including a photoconductor, a charging device disposed around the photoconductor and a developing device that develops toner, and an endless belt that rotates around the image forming unit;
The endless belt has an air inflow port on one side and an air outflow port on the other side on both sides of the endless belt in the width direction perpendicular to the circumferential rotation direction of the endless belt. Provided with a ventilation duct whose back surface forms one wall surface of the cooling space,
The cooling space of the ventilation duct is gradually widened from the air inlet side toward the air outlet side.
From the air inlet of the ventilation duct to the air outlet through the cooling space, the endless belt is cooled by flowing air in the width direction over the entire width of the back surface along the back surface of the endless belt. An image forming apparatus characterized by being configured as described above. The image forming apparatus according to claim 1 .
An image forming apparatus, wherein an intake side duct communicating with the air inlet of the ventilation duct and the outside is provided on an inner surface side of an openable / closable exterior cover of the apparatus main body. The endless belt is an intermediate transfer belt that primarily transfers a toner image formed by the image forming unit to a surface and conveys the toner image to a secondary transfer position on a sheet;
The ventilation duct is provided on the back side of the intermediate transfer belt in a region upstream of the primary transfer position and downstream of the secondary transfer position in the circumferentially rotating region of the intermediate transfer belt. the image forming apparatus according to claim 1 or 2, characterized in that. In an image forming apparatus comprising: an image forming unit including a photoconductor, a charging device disposed around the photoconductor and a developing device that develops toner, and an endless belt that rotates around the image forming unit;
The endless belt has an air inflow port on one side and an air outflow port on the other side on both sides of the endless belt in the width direction perpendicular to the circumferential rotation direction of the endless belt. Provided with a ventilation duct whose back surface forms one wall surface of the cooling space,
From the air inlet of the ventilation duct to the air outlet through the cooling space, the endless belt is cooled by flowing air in the width direction over the entire width of the back surface along the back surface of the endless belt. And
The endless belt is an intermediate transfer belt that primarily transfers a toner image formed by the image forming unit to a surface and conveys the toner image to a secondary transfer position on a sheet;
The ventilation duct is provided on the back surface side of the intermediate transfer belt in a region upstream of the primary transfer position and downstream of the secondary transfer position in the circumferentially rotating region of the intermediate transfer belt;
An intermediate transfer belt cleaner for removing toner remaining on the surface of the intermediate transfer belt in a region downstream of the secondary transfer position in the circumferentially rotating region of the intermediate transfer belt;
An image forming apparatus, wherein the ventilation duct is provided in a region immediately after the intermediate transfer belt passes through the intermediate transfer belt cleaner. The image forming apparatus according to claim 4.
An image forming apparatus , wherein an intake side duct communicating with the air inlet of the ventilation duct and the outside is provided on an inner surface side of an openable / closable exterior cover of the apparatus main body .

Images