JPH07160180A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device capable of surly preventing the transport defect of an image carrier due to the melt sticking of powder developer to the guide means for guiding an image carrier to a fixing means and stably performing the fixing operation. CONSTITUTION:The cooled face 101A, comprising the face of the peltier element 101 composed of the face becoming cooled on impressing the power and the other face becoming heated, is fitted in the state of contact with the upper part guide 81 and the lower part guide 82 comprising the inlet guide 80 becoming high temp. by the heat of the heating roller 41 provided on the front side of the fixing point 50 as the pressurized contact part between the heating roller 41 and the pressure roller 43. Then, the fixing device is constituted so as to positively cooling the upper part guide 81 and the lower part guide 82 affected by the heat of the heating roller 41 by applying the cooling effect of the peltier element 101 for lowering below the fusing temp. of the toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, an electrostatic copying machine,
The present invention relates to a fixing device applied to an image forming apparatus such as a laser printer, and more particularly, to a heating roller type fixing device for welding a developer image made of powder developer onto an image carrier.

[0002]

2. Description of the Related Art In recent years, a heating roller type fixing device has been widely used in an electrophotographic image forming apparatus because it has a feature of being capable of stable fixing while having a small size.

In this heating roller type fixing device, a heating roller that heats and conveys an image carrier (paper) carrying a developer image (toner image) made of powder developer (toner), and the heating roller. On the other hand, a pressure roller that conveys the image carrier while pressing the image carrier is provided, and the image carrier passes through a fixing point that is a pressure contact portion between the heating roller and the pressure roller. The developer image is fused and pressure-bonded.

Further, in this type of fixing device, usually, a sheet metal inlet guide is provided on the inlet side of the fixing means, that is, on the front side of the fixing point which is the pressure contact portion between the heating roller and the pressure roller. An image carrier such as a sheet on which a developer image is formed is guided to the fixing point via the inlet guide.

Conventionally, the inlet guide is not structured to be positively cooled, and is heated to a high temperature by the heat of the heating roller. On the other hand, a part of the unfixed developer image adheres to the entrance guide when the front end or the rear end of the image carrier on which the unfixed developer image is formed contacts the entrance guide, or is placed near the entrance guide. Floating developer scattered from other units such as a cleaning device and a developing device installed is in a state of being affected by the developer.

[0006]

As described above, the conventional fixing device does not have a structure that positively cools the inlet guide, and the unfixed developing process is performed on the inlet guide having a high temperature. When the agent adheres or the floating developer scattered from other units adheres, the adhered developer melts and adheres to the inlet guide. If the toner accumulation becomes severe, the conveyance of the image carrier is hindered, and there is a problem that the image carrier is clogged in the conveyance path.

The present invention has been made in view of the above circumstances. An object of the present invention is to prevent the conveyance failure of the image carrier due to the fusion of the powder developer to the guide means for guiding the image carrier to the fixing means. It is an object of the present invention to provide a fixing device that can be reliably prevented and can perform a stable fixing operation.

[0008]

As a first means for solving the above-mentioned problems of the present invention, a heating roller for heating and conveying an image carrier carrying a developer image composed of a powder developer, A fixing unit that includes a pressure roller that conveys the image carrier while pressing the image carrier against the heating roller, and a fixing unit that melts and fixes the developer image on the image carrier, and a direction in which the image carrier is carried in the fixing unit. And a guide means for guiding the image bearing member carrying the unfixed developer image to the fixing means, and a powder adhered to the guide means after cooling the guide means to the melting temperature of the powder developer or lower. This is composed of a fusion preventing means for preventing the fusion of the developer.

As a second means, a heating roller that heats and conveys an image bearing member carrying a developer image made of a powdery developer, and the image bearing member is pressed against the heating roller. A fixing unit configured to convey and fix the developer image on the image carrier, and a non-fixed developer image carrier that is provided in front of the fixing unit in the carrying direction of the image carrier. The guide means for guiding the image carrier to the fixing means, and the means for cooling the surface of the guide means facing the conveying path of the image carrier and supplying heat to the fixing means. It is a thing.

As a third means, a heating roller that heats and conveys an image carrier carrying a developer image composed of a powder developer, and the image carrier is pressed against the heating roller. A fixing unit that includes a pressure roller that conveys the image of the developer, and a fixing unit that melts and fixes the developer image on the image carrier; and a conveyance path for the image carrier that is provided in front of the image carrier carrying direction to the fixing unit. A guide means for guiding the image carrier to the fixing means and a surface of the guide means not facing the conveyance path of the image carrier, the guide means is cooled by one surface and the heat is radiated by the other surface. The cooling means and the transfer means are provided between the cooling means and the fixing means and transfer the heat radiated from the cooling means to the heating roller or the pressure roller of the fixing means. .

As the fourth means, the powder on the image carrier conveyed through the conveying means provided with an air flow generating means for generating an air flow for stabilizing the conveyance of the image carrier. A fixing device for fusing and fixing a developer image composed of a developer, comprising: a heating roller that conveys an image carrier carrying the developer image while heating it; and a pressing roller that presses the image carrier against the heating roller. A fixing unit configured to melt and fix the developer image on the image carrier, and a pressure roller that conveys the developer image to the image carrier; A guide means for guiding the image bearing member carrying the developer image on the fixing means to a fixing means, and cooling the guide means to a temperature below the melting temperature of the powder developer to fuse the powder developer adhered to the guide means. And a cooling means for preventing Retirement unit, in which a structure consisting of duct means for directing an air flow generated by the air flow generating means to flow along said guide means.

[0012]

According to the first means of the present invention, the guide means which is influenced by the heat of the heating roller is provided by the fusion preventing means.
Since it is possible to actively cool the powder developer to a temperature below the melting temperature, even if unfixed developer is attached or floating developer scattered from other units is attached,
This adhered developer does not melt and stick to the guide means, and it is possible to reliably prevent defective conveyance of the image carrier due to the fusion of the powder developer to the guide means, and stable fixing. It becomes possible to perform an operation.

According to the second means, the means for cooling the surface of the guide means facing the conveying path of the image carrier and supplying heat to the fixing means is provided.
Even if unfixed developer adheres or floating developer scattered from other units adheres, the adhered developer does not melt and stick to the guide means.
It is possible to reliably prevent the defective conveyance of the image carrier due to the fusion of the powder developer to the guide means, and to perform a stable fixing operation. Further, the radiated heat can be effectively used as residual heat of the fixing unit and the like, and the adverse effect due to the heat flowing to other portions can be prevented.

According to the third means, a cooling means for cooling the guide means on one surface and radiating heat on the other surface is provided on the surface of the guide means not facing the conveying path of the image carrier. Further, between the cooling means and the fixing means, there is provided a transmission means for transmitting the heat radiated from the cooling means to the heating roller or the pressure roller of the fixing means.
Even if unfixed developer adheres or floating developer scattered from other units adheres, the adhered developer does not melt and stick to the guide means.
It is possible to reliably prevent the defective conveyance of the image carrier due to the fusion of the powder developer to the guide means, and to perform a stable fixing operation. Further, the radiated heat can be effectively used as residual heat of the heating roller or the pressure roller, and the adverse effect caused by the heat flowing to other parts can be prevented.

Further, according to the fourth means, the cooling means of the air flow guided by the duct means keeps the guide means, which is affected by the heat of the heating roller, below the melting temperature of the powder developer. Since it is possible to positively cool, even if unfixed developer adheres or floating developer scattered from other units adheres, the adhered developer melts and sticks to the guide means. It is possible to surely prevent the defective conveyance of the image carrier due to the fusion of the powder developer to the guide means, and to perform the stable fixing operation.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 shows the appearance of an image forming apparatus to which an embodiment of the fixing device of the present invention is applied, and FIG. 2 shows the internal structure.

In the figure, reference numeral 1 is a main body of the apparatus, and the main body 1 of the apparatus contains an image forming means 2 for forming an image by an image forming process such as charging, exposure, development, transfer and cleaning. Further, a platen glass 3 as a document placing table and a platen cover 4 for pressing the document A set on the platen glass 3 are provided on the upper surface of the apparatus main body 1. Further, an operation panel 5 (see FIG. 1) is provided on the front end edge portion of the upper surface of the apparatus body 1.

On the right side of the apparatus main body 1, paper feed cassettes 6A and 6B containing paper P as an image carrier to be supplied to the image forming means 2 are mounted, and the apparatus main body 1 is also installed.
A paper discharge tray 7 for accommodating the fixed paper P is provided on the left side of the.

The image forming means 2 is constructed as follows. That is, the drum-shaped photoconductor 10 as an image support is arranged at substantially the center of the apparatus main body 1.

Around the photosensitive member 10, a charging device 11 as charging means is arranged along the rotation direction (arrow direction) of the photosensitive member 10.
Exposure unit 12 of exposure device 12 as electrostatic latent image forming means
A, a developing device 13 as a developing device, a transfer device 14 as a transfer device, a peeling device 15 as a peeling device, a cleaning device 16 as a cleaning device, a static eliminator 17 as a static eliminating device, and the like are sequentially arranged. .

Further, in the main body 1 of the apparatus, a paper P automatically fed from the paper feed cassette 6A (or 6B) is provided with an image transfer portion 18 between the photoconductor 10 and the transfer device 14. A sheet conveying path 20 is formed on the left side of the apparatus main body 1 and leads to the sheet discharge tray 7.

The image transfer section 18 of the sheet conveying path 20.
A pair of aligning rollers 21 is arranged on the upstream side, and a fan duct unit 22 as an air flow generating means for generating an air flow for stabilizing the transport of the sheet P is attached on the downstream side. A transport device 23 as a means,
A fixing device 24 of the present invention, which will be described later, and a pair of discharge rollers 2
5 are arranged.

In the vicinity of the mounted portion of the paper feed cassette 5, a paper feed roller 24 for picking up the paper P one by one and feeding it to the paper transport path 20 is provided. The exposure device 12 is provided in the upper part of the apparatus main body 1.

The exposure apparatus 12 illuminates an original A set on a platen glass 3 provided on the upper surface of the apparatus main body 1 with an exposure lamp 31 whose back is surrounded by a reflector 30, and reflects light from the original surface. First Mira-32, Second
Lens 3 through the third mirror 33 and the third mirror 34
5, and further, the light transmitted through the lens 35 is guided to the photoconductor 10 via the fourth mirror 36.

The exposure lamp 31 and the first mirror-3
2 is mounted on a first carriage 40 which is capable of reciprocating along the lower surface of the platen glass 3, and a second mirror-3.
The third and third mirrors 34 correspond to the first carriage 40.
It is mounted on the second carriage 41 that moves in the same direction at half the speed. Then, these carriages 40 and 41
However, by moving from the left to the right in the drawing in the state of FIG. 2, the document A set on the platen glass 3 is scanned and the image corresponding to the document A is slit-exposed on the photoconductor 10. Has become.

In copying the original A, the photoconductor 10 rotates in the direction of the arrow and is uniformly charged by the charging device 11. Then, an image corresponding to the document A is slit-exposed by the exposure device 12 on the uniformly charged photoconductor 10 to form an electrostatic latent image on the photoconductor 10.

The electrostatic latent image formed on the photoconductor 10 is developed by applying a powder developer (hereinafter referred to as toner) by the developing device 13, and the developer image (hereinafter, referred to as a toner) on the photoconductor 10 is developed.
A toner image) is formed.

On the other hand, in synchronism with the toner image forming operation on the photoconductor 10, the paper P is sent to the image transfer section 17 through the aligning roller pair 21, and the photoconductor 10 is operated by the transfer device 14. The upper toner image is transferred to the paper P.

Then, the paper P on which the toner image is transferred is
After being peeled by the peeling device 15 by AC corona discharge, the toner image is guided to the fixing device 24 via the conveying device 23, and the toner image is fused and fixed on the paper P by the fixing device 24. After that, the paper P is discharged onto the paper discharge tray 7 by the paper discharge roller pair 23.

After the toner image is transferred onto the paper P, the cleaning device 16 removes the residual toner from the photoconductor 10 to bring the photoconductor 10 into a clean state to enable the next copying operation.

The fixing device 24 has the following structure. That is, as shown in FIG. 3, the fixing device 24 is a heating roller type fixing device, and is located on the upper surface side of the paper transport path 20 and includes a heating roller (fuser roller) 41 having a built-in heater lamp 40 as a heat source. ,
The pressure roller (press roller) 43 is provided on the lower surface side of the paper transport path 20 and is pressed against the heating roller 41 by the urging force of the urging mechanism 42.

Then, the heating roller 41 and the pressure roller 43
By passing the sheet P through the fixing point 50 which is a pressure contact portion with the sheet P, the toner T on the sheet P is fused and fixed to the sheet P.

The heating roller 41 and the pressure roller 43 are
It is surrounded by a housing 63 composed of an upper casing 61 and a lower casing 62, and has a structure in which heat does not escape to the outside as much as possible so as to secure a favorable temperature atmosphere necessary for fixing. Further, a fuser guard 64 is provided on the upper surface side of the upper casing 6 so as to cover the upper casing 6 as a safety means for preventing burns.

On the circumference of the heating roller 41, the heating roller 4
1. The thermistor 70 for detecting the temperature of 1, the peeling claw 71 for peeling the paper P from the heating roller 41 and guiding it in the direction of the discharge roller pair 25, the blade claw 72 for scraping off the residual toner on the heating roller 41, and the heating roller. Cleaning roller 7 for cleaning while applying the anti-offset liquid to the surface of 41
3 are provided in contact with each other.

The thermistor 70 is connected to a control circuit (not shown) and supplies the detected surface temperature of the heating roller 41 to the control circuit. When the surface temperature is lower than the fixing temperature, the power supply to the heater lamp 40 as a heat source is continued, and when the surface temperature exceeds the fixing temperature, the power supply to the heater lamp 40 is cut off. Then, the surface temperature of the heating roller 41 is controlled so as to always maintain a constant range, that is, about 190 ± 5 ° C. at which good fixing is possible.

Further, the entrance side of the fixing means 45 consisting of the heating roller 41 and the pressure roller 43, that is, the heating roller 4
1 and the pressure roller 43, the fixing point 50 which is a pressure contact portion.
As shown in FIG. 4, an inlet guide 80 as guide means on the inlet side is provided on the front side of the sheet P. The sheet P on which the toner image is formed is fixed through the inlet guide 80. Is configured to lead to. The inlet guide 80 includes an upper guide 81 made of sheet metal fixed to the upper casing 61 and a lower guide 82 made of sheet metal fixed to the lower casing 62.

An exit guide 83 is provided on the discharge side of the fixing point 50 so that the paper P passing through the fixing point 50 is guided to the discharge roller pair 25. The outlet guide 83 is an upper guide 84 made of sheet metal.
And a lower guide 85 made of sheet metal.

By the way, the entrance guide 80 of the fixing device 24
The upper guide 81 and the lower guide 82 constituting the above are in a state of becoming high temperature by the heat of the heating roller 41, but in the present invention, the upper guide 81 and the lower guide 8 are
2 is positively cooled by the cooling means 100 which is a fusion preventing means, and is cooled below the melting temperature of the toner T.

That is, this cooling means 100 is shown in FIG.
As shown in FIG. 4, the Peltier element 101 as a cooling means, one surface of which is cooled by the application of electricity and the other of which is heated, is placed in a state in which the cooling surface 101A made of the one surface is in contact with the upper guide 81 and the lower guide 82. It is installed.

The upper guide 81 and the lower guide 8
Since the temperature rise rate of No. 2 varies depending on the size of the fixing device and the arrangement of accessory parts, the number of Peltier elements 101 attached to the upper guide 81 and the lower guide 82 is preferably set experimentally as appropriate.

As described above, in this embodiment, the upper guide 81 and the lower guide 82 are affected by the heat of the heating roller due to the cooling action of the Peltier element 101.
Is actively cooled to a temperature below the melting temperature of the toner T.

For this reason, the unfixed toner T reaches the leading end and the trailing end.
The unfixed toner T adheres to the upper guide 81 and the lower guide 82 when the paper P on which the unfixed toner T is fed is contacted with the upper guide 81 and the lower guide 82.
(See FIG. 2) The developing device 13 arranged around the
Even if the floating toner T scattered from other units such as the cleaning device 16 adheres, the adhered toner T does not melt and adhere to the upper guide 81 and the lower guide 82. It is possible to reliably prevent the conveyance failure of the paper P due to the fusing of the toner T, and to perform a stable fixing operation.

Further, although the Peltier element 101 described above has a cooling effect, it radiates heat, so as shown in detail in FIG. 5, the heat radiation surface 101, which is the surface opposite to the cooling surface 101A.
A heat sink radiating plate 102 as a transmitting means is provided at B, and the heat H is used to keep the ambient temperature in the housing 63 warm. Although FIG. 5 shows the lower guide 82 side, the upper guide 81 side has the same structure.

One end side of the heat sink heat radiating plate 102 extends so as to be substantially parallel to the back surface side of the upper guide 81 (or lower guide 82) and the roller surface of the heating roller 41 (or pressure roller 43). The heat dissipation area is enlarged.

On the surface of the extended portion, the heat insulating material 1
03 is attached, and the heat insulating material 103 prevents the heat of the heat sink radiator plate 102 from being transferred to the upper guide 81 (or the lower guide 82), and also the heating roller 41 (or the pressure roller 43). Is prevented from being transferred to the heat sink heat dissipation plate 102 and the upper guide 81 (or the lower guide 82). Then, the upper guide 81 (or the lower guide 8
2) is efficiently cooled by the Peltier element 101.

Next, another embodiment of the present invention will be described with reference to FIGS. In this embodiment, instead of the Peltier element 101 described above, an air flow F for stabilizing the conveyance of the paper P generated by the fan duct unit 22 as an air flow generating means is used for cooling the lower guide 82 of the inlet guide 80. It is intended to be used.

That is, the endless conveyor belt 112 with holes which is wound around the driving roller 110 and the driven roller 111.
A fan duct unit 22 including a fan motor 113 that is a suction source and a duct 115 having a suction port 114 formed on the upper surface is provided on the lower surface side of the transport device 23 that is composed of.

The lower guide 8 is provided in the duct 115.
The auxiliary duct 120 as a duct means is branched so as to be in close contact with the second vertical support portion 82A, and a suction port 121 is formed at one end of the auxiliary duct 120.

Then, the fan motor 113 which is the suction source.
The air flow F flowing in the duct 115 and the auxiliary duct 121 as indicated by the arrow is generated by the operation of the lower guide 82.
Is designed to be cooled.

For this reason, the unfixed toner T reaches the leading end and the trailing end.
The unfixed toner T adheres to the lower guide 82 by being fed in the sheet P on which the unfixed toner T is attached, and the unfixed toner T is attached or is arranged around the photoconductor 10 (see FIG. 2). Even if the floating toner T scattered from other units such as the developing device 13 and the cleaning device 16 adheres, the adhered toner T does not melt and adhere to the lower guide 82. It is possible to reliably prevent the conveyance failure of the paper P due to the fusion of the toner T onto the paper 82, and to perform a stable fixing operation. In addition, it goes without saying that the present invention can be variously modified and implemented without departing from the spirit of the present invention.

[0051]

As described above, according to the fixing device of the present invention, the guide means affected by the heat of the heating roller can be positively cooled so as to be below the melting temperature of the powder developer. Therefore, even if unfixed developer adheres or floating developer scattered from other units adheres, the adhered developer does not melt and stick to the inlet guide. In addition, it is possible to reliably prevent the defective conveyance of the image carrier due to the fusion of the powder developer to the guide means, and to perform a stable fixing operation. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is an external perspective view of an image forming apparatus to which an embodiment of a fixing device according to the present invention is applied.

FIG. 2 is a schematic diagram showing an internal configuration of the image forming apparatus.

FIG. 3 is a front sectional view showing an embodiment of a fixing device of the present invention.

FIG. 4 is a sectional view of the vicinity of the entrance of the fixing device.

5 is a partially enlarged view of FIG.

FIG. 6 is a schematic plan view of a main part showing another embodiment of the fixing device of the present invention with a part cut away.

FIG. 7 is likewise a front sectional view.

[Explanation of symbols]

22 ... Fan duct unit (air flow generating means), 23
... conveying device (conveying means), 24 ... fixing device, 40 ... heater lamp (heat source), 41 ... heating roller, 42 ... biasing mechanism, 43 ... pressure roller, 45 ... fixing means, 50 ... fixing point, 61 ... Upper casing, 62 ... Lower casing, 63 ... Housing, 80 ... Inlet guide (guide means), 81 ... Upper guide, 82 ... Lower guide, 100 ...
Cooling means (fusion prevention means), 101 ... Peltier element (cooling means), 101A ... Cooling surface, 101B ... Radiating surface, 10
2 ... Heat sink radiating plate (transmitting means), 103 ... Insulating material, 113 ... Fan motor (suction source), 114 ... Suction port, 115 ... Duct, 120 ... Auxiliary duct (duct means), 121 ... Suction port, P ... Paper (Image carrier), T ... Toner, F ... Air flow.

Claims (4)

[Claims] 1. A heating roller which conveys an image bearing member carrying a developer image made of powder developer while heating it, and a pressure roller which conveys while pressing the image bearing member against the heating roller. And a fixing means for melting and fixing the developer image on the image carrier, and the image carrier carrying the unfixed developer image provided in front of the image carrier carrying-in direction to the fixing means. Guide means for guiding to the means, and fusion preventing means for preventing fusion of the powder developer adhering to the guide means by cooling the guide means to a melting temperature of the powder developer or lower. Fixing device. 2. A heating roller for heating and carrying an image carrier carrying a developer image composed of a powder developer, and a pressure roller for carrying the image carrier while pressing the image carrier against the heating roller. And a fixing means for melting and fixing the developer image on the image carrier, and the image carrier carrying the unfixed developer image provided in front of the image carrier carrying-in direction to the fixing means. A fixing device comprising: a guide unit that guides the fixing unit; and a unit that cools a surface of the guide unit facing the transport path of the image carrier and supplies heat to the fixing unit. 3. A heating roller that heats and conveys an image bearing member carrying a developer image made of a powdery developer, and a pressure roller that conveys while pressing the image bearing member against the heating roller. And a fixing means for melting and fixing the developer image on the image carrier, and a fixing means provided in front of the image carrier carrying-in direction to the fixing means to form a conveyance path of the image carrier and to fix the image carrier on the image carrier. Guide means for guiding to the fixing means, cooling means provided on a surface of the guide means that does not face the conveying path of the image carrier, and cooling the guide means on one surface and radiating heat on the other surface; And a transfer unit which is provided between the fixing unit and the fixing unit, and which transfers the heat radiated from the cooling unit to the heating roller or the pressure roller of the fixing unit. 4. A developer consisting of a powdered developer on an image carrier conveyed through a conveying means provided with an air flow generating means for generating an air flow for stabilizing the conveyance of the image carrier. A fixing device for fusing and fixing an image, comprising: a heating roller that heats and conveys an image carrier carrying the developer image; and a pressure roller that conveys while pressing the image carrier against the heating roller. And a fixing unit for melting and fixing the developer image on the image carrier, and the unfixed developer image which is provided in front of the image carrier carrying direction to the fixing unit and is conveyed through the conveying unit. Guide means for guiding the image bearing member carrying the toner to the fixing means, and cooling means for cooling the guide means to a melting temperature of the powder developer or lower to prevent fusion of the powder developer adhering to the guide means. ,, wherein the cooling means is the air A fixing device comprising duct means for guiding an air flow generated by the flow generating means so as to flow along the guide means.