JP2009053312A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus where air is made to flow in the shaft direction of a developing roller along the housing of a developing means, to lessen flow loss and also enhance a cooling effect with simple structure, and further which softens temperature rise of toner inside, to uniformize toner concentration and not to cause image irregularity. <P>SOLUTION: The image forming apparatus includes: the developing means which incorporates the developing roller to develop a latent image formed on an image carrier; a driving device which drives the developing means; a first panel which is arranged on one end face side of the shaft of the developing roller and to which the driving device is attached; and a second panel which is arranged on the other end face side thereof. The apparatus is provided with a second aperture part on the second panel, and is provided with a first aperture part on the first panel and further a ventilating fan on the outside of the aperture part of the first panel. A channel for flux between the first and the second aperture parts is formed along the outer wall surface of the housing in the shaft direction of the developing roller, to cool the developing means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a cooling unit for cooling a developing unit having a developing roller.

  2. Description of the Related Art Conventionally, in an image forming apparatus, the temperature of the inside of the image forming apparatus is increased by a heat source of a fixing device, and the developer is formed and supplied by stirring and circulation of toner and a carrier sent from a hopper. It is known that the temperature rises due to the heat generated. The toner heated by the developing agent stirring heat of the developing means and the frictional heat of the bearing portion is softened, so that the fluidity of the toner is deteriorated and the toner and carrier concentrations are non-uniform. In some cases, image unevenness occurred when the toner flew on the screen.

  In order to prevent this, for example, an attempt as shown in Patent Document 1 in which a cooling device is attached has been made. That is, outside air is taken in the axial direction of the developing roller and in a direction perpendicular thereto, and the air around the developing means is sucked up into the upper duct where the temperature easily rises and is exhausted to the back. However, the flow path is complicatedly bent many times in the direction perpendicular to or parallel to the axial direction of the developing roller, the flow loss is large, and the cooling effect does not increase for the installation cost of the cooling means.

In addition, outside air is taken in from a direction perpendicular to the axis of the developing roller, and is bent and discharged in a parallel direction at a position away from the developing roller. However, in this case as well, the path of the flow path is bent many times in a direction perpendicular to or parallel to the axial direction of the developing roller, the flow rate is large, and the cooling effect does not increase for the installation cost of the cooling device. It was.
JP 2006-145727 A

  As described above, in the conventional cooling means, the curve of the air path is increased, the flow rate efficiency is lowered, and the effect of the air flowing substantially to the developing means is reduced.

  The present invention eliminates the disadvantages of the prior art and further improves the efficiency of the cooling of the developing means with a simple structure, thereby mitigating the temperature rise of the toner inside, thereby achieving uniform toner concentration. For the purpose. Accordingly, it is an object to provide an image forming apparatus that does not cause image unevenness.

This object is achieved by any one of the following technical means 1 to 3.
1. Development having an image carrier and a developing roller for developing a latent image formed on the image carrier, and having a housing provided with a slit opening at a position facing the image carrier of the developer roller Means, a driving device that drives the developing means, a first panel that is disposed on one end surface side in the axial direction of the developing roller and has the driving device attached thereto, and the other end surface in the axial direction of the developing roller In an image forming apparatus having a second panel disposed on the side,
The second panel in which the second opening is formed is provided outside the image forming region in the axial direction of the developing roller, and the first panel in which the first opening is formed is the development panel. An exhaust fan is provided outside the image forming area in the axial direction of the roller, and an exhaust fan for exhausting air in the image forming apparatus is provided outside the first panel. The first opening and the second The opening is formed so that at least a part thereof overlaps when viewed from the axial direction of the developing roller, and the flux of air flowing from the second opening to the first opening is the housing. An image forming apparatus, wherein the image forming apparatus is configured to flow along an outer wall surface in the axial direction of the developing roller.
2. 2. The image forming apparatus according to 1, wherein an air intake fan that sucks outside air into the image forming apparatus is provided outside the second panel.
3. The first panel forms a part of a frame on the main body side, the second panel includes an auxiliary panel provided in parallel to the second panel, and a platform on which the developing means is placed and fixed The developing means, which integrally forms a moving frame, moves the moving frame relative to the first panel, and is provided integrally with the second panel by the moving frame, includes the first panel. The image forming apparatus according to 1 or 2, wherein the image forming apparatus is detachably attached to the driving device.

  According to the present invention, it is possible to obtain an image forming apparatus in which the temperature rise of the developing means is mitigated and image unevenness caused by development unevenness is not generated.

  An example of an embodiment according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional configuration diagram showing an embodiment of an image forming apparatus of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7, a paper feeding and conveying means ( And a fixing device 24 as fixing means. A document image reading device SC is disposed on the upper part of the frame 110 on the main body side of the image forming apparatus 1.

  An image forming unit 10Y that forms a yellow image includes a photosensitive drum 1Y as a first image carrier, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a primary unit arranged around the photosensitive drum 1Y. A primary transfer roller 5Y as a transfer unit and a cleaning unit 6Y are provided.

  The image forming unit 10M that forms a magenta image includes a photosensitive drum 1M as a first image carrier, a charging unit 2M disposed around the photosensitive drum 1M, an exposing unit 3M, a developing unit 4M, a primary unit A primary transfer roller 5M as a transfer unit and a cleaning unit 6M are provided.

  An image forming unit 10C that forms a cyan image includes a photosensitive drum 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary unit arranged around the photosensitive drum 1C. A primary transfer roller 5C as a transfer unit and a cleaning unit 6C are provided.

  The image forming unit 10K that forms a black image includes a photosensitive drum 1K as a first image carrier, a charging unit 2K, an exposing unit 3K, a developing unit 4K, and a primary transfer unit arranged around the photosensitive drum 1K. Primary transfer roller 5K and cleaning means 6K.

  Each of the developing units 4Y, 4M, 4C, and 4K is yellow (Y), magenta (M), cyan (C), or black (charged to the same polarity as the charging polarity of the photosensitive drums 1Y, 1M, 1C, and 1K. K) two-component developers made of toner of each color are accommodated. However, the developer may be a one-component developer. Each developing device includes, for example, developing rollers 4Y1, 4M1, 4C1, which are developer carriers formed of cylindrical nonmagnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm. 4K1 is provided.

  The developing rollers 4Y1, 4M1, 4C1, and 4K1 are kept out of contact with the photosensitive drums 1Y, 1M, 1C, and 1K by abutting rollers (not shown) with a predetermined gap, for example, 100 to 1000 μm. The photosensitive drums 1Y, 1M, 1C, and 1K rotate in the forward or reverse direction.

  At the time of development, a developing bias voltage that superimposes an AC voltage on a DC voltage or DC voltage having the same polarity as the toner is applied to each of the developing rollers 4Y1, 4M1, 4C1, and 4K1. As a result, non-contact reversal development is performed on the latent images by the exposure units 3Y, 3M, 3C, and 3K on the photosensitive drums 1Y, 1M, 1C, and 1K.

  In general, so-called external additives are added to the toner for the purpose of improving fluidity and improving cleaning properties. Among these, examples of the lubricant relating to the present invention include salts of zinc stearate, aluminum, copper, magnesium, calcium and the like, and salts of zinc oleate, manganese, iron, copper, magnesium and the like. Further, metal salts of higher fatty acids such as zinc palmitate, copper, magnesium, calcium and the like, zinc linoleic acid, salts such as calcium, zinc ricinoleic acid, salts such as calcium and the like. In addition, a lubricant is mixed with the external additive.

  The amount of these external additives added is about 0.01 to 10% by mass with respect to the toner.

  As shown in FIG. 1, the intermediate transfer body unit 7 is wound around a plurality of rollers 71, 72, 73, 74, and is supported by a semiconductive endless belt-like endless belt-like intermediate transfer body 70 ( Hereinafter, it is referred to as an intermediate transfer belt.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred onto the intermediate transfer belt 70 that is rotated by the primary transfer rollers 5Y, 5M, 5C, and 5K, and the combined color. An image is formed.

  The transfer material P as a recording medium housed in the paper feed cassette 20 is fed by the paper feeding means 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D and a registration roller 23, and then the secondary transfer roller 5A. The color images are transferred onto the transfer material P at once.

  The transfer material P onto which the color image has been transferred is fixed by the fixing device 24, sandwiched between the paper discharge rollers 25, and placed on the paper discharge tray 26.

  The above describes the state in which the image is formed on one side of the transfer material P. However, in the case of double-sided copying, the paper discharge switching member 27 is switched, the paper guide portion 28 is opened, and the transfer material P is indicated by an arrow. It is conveyed in the direction a.

  Further, the transfer material P is transported downward by the transport mechanism 29, switched back by the paper reversing unit 30, and transported into the duplex copying paper supply unit 31 with the rear end portion of the transfer material P serving as the leading end portion. .

  The transfer material P moves the conveyance guide 32 provided in the double-sided copy paper supply unit 31 in the paper supply direction, and re-feeds the transfer material P with the paper supply rollers 33A, 33B, 33C, 33D. To the conveyance path R.

  In this manner, as described above, the transfer material P is again conveyed to the secondary transfer position, the toner image is transferred to the back surface of the transfer material P, fixed by the fixing device 24, and then discharged to the discharge tray 26. To do.

  In the fixing device 24, the transfer material P is fixed by applying heat and pressure between the fixing roller 24A and the pressure roller 24B.

  Further, after the color image is transferred to the transfer material P by the secondary transfer roller 5A, the residual toner is removed by the cleaning unit 6A from the intermediate transfer belt 70 from which the transfer material P is separated by curvature.

  During the image forming process, the primary transfer roller 5K is always in pressure contact with the photosensitive drum 1K, and the other primary transfer rollers 5Y, 5M, and 5C are respectively associated with the corresponding photosensitive drums 1Y and 1M only during color image formation. 1C.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction, and an endless belt-shaped intermediate transfer body unit 7 is arranged on the left side of each of the photosensitive drums 1Y, 1M, 1C, and 1K.

  The image forming apparatus is provided with a cooling unit that cools the developing units 4Y, 4M, 4C, and 4K.

  Next, a state in which a cooling device for cooling the developing means is mounted and a cooling air flow path will be described with reference to a top view of FIG. 2, a front sectional view of FIG. 3, and a perspective view of FIG. Here, since the four developing units 4Y, 4M, 4C, and 4K have the same structure, only the Y-color developing unit 4Y will be described.

  In the figure, the developing means 4Y has a housing 4Y2 that forms a slit S that opens to the photosensitive drum 1Y.

  The housing 4Y2 has a developing roller 4Y3 as a developer carrying member constituted by a cylindrical non-magnetic sleeve, and a plurality of magnetic field generating means that are built in the developing roller 4Y3 and form a rotational sliding surface thereof. A cylindrical magnet body 4Y4 formed in a shape and fixed in position is provided. In addition, two stirring screws 4Y5, a magnet roller 4Y6, and a panty regulation plate 4Y7 are provided. The developer having a uniform concentration is transferred to the upper magnet roller 4Y6 by the two agitating screws 4Y5 that convey the developer while stirring, and the developing roller passes from the magnet roller 4Y6 through the spike-setting plate 4Y7. It is supplied from above toward 4Y3. Then, the toner of the phenomenon agent flies to the photosensitive drum 1Y through the slit S, and a toner image is created. The surplus phenomenon agent is returned to the stirring screw 4Y5, and further development is continued while being collected and circulated.

  Each of the phenomenon means 4Y, 4M, 4C, and 4K is installed on the frame 125 of the moving frame 127 formed by the second panel 122, the auxiliary panel 124, and the four frames 125 that connect the second panel 122 and the auxiliary panel 124. The

  On the other hand, the first panel 112 is provided as a member constituting a part of the frame 110 on the main body side in the image forming apparatus 1, and the developing units 4Y, 4M, 4C, and 4K are driven to the first panel 112, respectively. A driving device 114 is attached. When the moving frame 127 is slid and mounted on the rail 117 provided on the frame 110 on the main body side, the developing units 4Y, 4M, 4C, and 4K are connected to the driving devices 114, respectively. It is like that. The moving frame 127 can be loaded into the main body by opening a door 118 provided on a part of the main body side frame 110 close to the second panel 122.

  In addition, it is desirable that the second panel 122 is disposed on the side where the user faces in the state of use of the image forming apparatus.

  Each of the developing units 4Y, 4M, 4C, and 4K forms a unit including the photosensitive drums 1Y, 1M, 1C, and 1K and the cleaning units 6Y, 6M, 6C, and 6K. Further, the image forming units 10Y, 10M, 10C, and 10K can be incorporated in the frame 127 together with the charging units 2Y, 2M, 2C, and 2K and the exposure units 3Y, 3M, 3C, and 3K.

  The first panel 112 is provided with a first opening 113, and the second panel 122 is provided with a second opening 123. As shown in the figure, an exhaust fan 116 is provided on the outer side of the first panel. Further, as shown in the figure, an intake fan 126 is preferably provided on the further outside of the second panel 122.

  The developing unit 4Y will be described again. 2, 3 and 4, the flow path of the flux formed by the second opening 123 and the first opening 113 is the outer wall surface of the housing 4Y2 parallel to the axis of the developing roller 4Y3. The cooling is performed while the flow rate loss is suppressed. The portion of the auxiliary panel 124 through which the flux passes is largely cut away so that the flow velocity is not hindered. Further, the number of times of bending of the upstream and downstream flow paths of the flux is small, and it is possible to shift from the intake state to the exhaust state while efficiently cooling the developing means.

  In this example, the first opening portion 113 and the second opening portion 123 have substantially the same shape and are formed at overlapping positions when viewed from the axial direction of the developing roller 4Y3. The same effect can be obtained even if the first opening and the second opening are formed in a partially overlapping shape and position.

  Incidentally, as shown in the top view of FIG. 5, the air flow path that has been conventionally air-cooled is such that the flow of intake air from the intake fan 126 is perpendicular to the developing roller 4Y3. This is a method in which bending is repeated, and the flow rate loss is increased.

  A comparison experiment was performed between the method of the present invention shown in the top view of FIG. 2, the cross-sectional view of FIG. 3, and the perspective view of FIG. 4, and the conventional method shown in the top view of FIG. The number of intake fans and exhaust fans used and the diameters of the fans were as follows for both the method of the present invention and the conventional method.

Exhaust fan 116: one axial fan with a fan diameter of 120 mm Suction fan 126: four axial fans with a fan diameter of 80 mm (for each developing means 4Y, 4M, 4C, 4K)
When this is mounted on the image forming apparatus 1 as shown in FIG. 1 and 7000 sheets of A4 size (3500 sheets are printed on both sides) is continuously copied, both end portions are parallel to the axis in the vicinity of the stirring screw 4Y5. And the temperature rise of the developer was measured by three temperature sensors T (shown in FIGS. 2, 3 and 5) arranged in the center. The results shown in Table 1 were obtained.

  At this time, when the front surface printed paper that has been fixed and warmed passes through the reverse conveyance path during the reverse side printing, the temperature of the path portion rises and the temperature of the developing means further increases. In this state, the temperature was measured. The rising temperature, which is the difference between the room temperature of 27 ° C. and the measured temperature immediately after printing 7000 sheets, was recorded. The rotation speed of the stirring screw was set to 430 rpm. The elevated temperature is an average value of the detected values of the three temperature sensors T.

  As shown in Table 1, in the present invention in which the flow path is formed substantially parallel to the developing roller shaft and the air is sucked and exhausted, the temperature rise is 15.6 ° C. In the conventional type in which the air was taken at a right angle, the temperature rise was 19.3 ° C. In the method of the present invention, no image unevenness occurred. However, in the conventional system, image unevenness which is not preferable in practice was slightly observed.

  In addition, this invention is not limited to the said embodiment, Even if it is a change and addition in the range which does not deviate from the summary of this invention, it is included in this invention.

1 is a cross-sectional configuration diagram illustrating an embodiment of an image forming apparatus of the present invention. FIG. 3 is a top view showing a state in which a cooling device for cooling the developing unit is mounted in the image forming apparatus of the present invention. FIG. 2 is a front sectional view showing a state in which a cooling device for cooling the developing unit is mounted in the image forming apparatus of the present invention. FIG. 4 is a perspective view showing a cooling air flow path when a cooling device for cooling the developing unit is mounted in the image forming apparatus of the present invention. FIG. 10 is a top view illustrating a cooling air passage for a developing unit of a conventional image forming apparatus.

Explanation of symbols

1Y, 1M, 1C, 1K Photosensitive drum 2Y, 2M, 2C, 2K Charging unit 3Y, 3M, 3C, 3K Image exposure unit 4Y, 4M, 4C, 4K Development unit 4Y2, 4M2, 4C2, 4K2 Housing 4Y3, 4M3 4C3, 4K3 Developing roller 4Y5, 4M5, 4C5, 4K5 Stir screw 5Y, 5M, 5C, 5K Primary transfer roller 110 Frame on main body side 112 First panel 113 First opening 114 Drive device 116 Exhaust fan 122 First Second panel 123 Second opening 124 Auxiliary panel 125 Base 126 Intake fan 127 Moving frame T Temperature sensor

Claims (3)

Development having an image carrier and a developing roller for developing a latent image formed on the image carrier, and having a housing provided with a slit opening at a position facing the image carrier of the developer roller Means, a driving device that drives the developing means, a first panel that is disposed on one end surface side in the axial direction of the developing roller and has the driving device attached thereto, and the other end surface in the axial direction of the developing roller In an image forming apparatus having a second panel disposed on the side,
The second panel in which the second opening is formed is provided outside the image forming region in the axial direction of the developing roller, and the first panel in which the first opening is formed is the development panel. An exhaust fan is provided outside the image forming area in the axial direction of the roller, and an exhaust fan for exhausting air in the image forming apparatus is provided outside the first panel. The first opening and the second The opening is formed so that at least a part thereof overlaps when viewed from the axial direction of the developing roller, and the flux of air flowing from the second opening to the first opening is the housing. An image forming apparatus, wherein the image forming apparatus is configured to flow along an outer wall surface in the axial direction of the developing roller. The image forming apparatus according to claim 1, further comprising an intake fan that sucks outside air into the image forming apparatus outside the second panel. The first panel forms a part of a frame on the main body side, the second panel includes an auxiliary panel provided in parallel to the second panel, and a platform on which the developing means is placed and fixed The developing means, which integrally forms a moving frame, moves the moving frame relative to the first panel, and is provided integrally with the second panel by the moving frame, includes the first panel. The image forming apparatus according to claim 1, wherein the image forming apparatus is attached to and detached from the driving device.

Images