JP2849003B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device having first to third fixing rollers, and a pressure contact portion between first and second fixing rollers and a pressure contact portion between second and third fixing rollers. And an electrophotographic apparatus such as a full-color copying machine in which a fixing unit is formed.

[0002]

2. Description of the Related Art For example, JP-A-51-98036 discloses a fixing device for a copying machine as an electrophotographic apparatus.
It comprises three heat rollers, upper, middle and lower, forming a first fixing section for full-color copying between the upper and middle heat rollers, and a second fixing section for black and white copying between the middle and lower heat rollers. A configuration in which a transfer paper transport belt is moved up and down in accordance with a fixing unit to be formed and used is described. In such a copying machine, black-and-white copying and full-color copying can be performed under fixing conditions suitable for each, and a good image can be obtained.

However, in the above-described copying machine, since both the upper and lower heat rollers are constantly pressed against the middle heat roller, the lower heat roller rotates even when the first fixing unit is used. Even when the second fixing unit is used, the upper heat roller rotates. The rotation direction of each of the upper, middle, and lower heat rollers is switched between when the first fixing unit is used and when the second fixing unit is used. For this reason, abrasion of the heat roller is apt to progress due to sliding contact with a cleaning roller and a thermistor for temperature detection and the like for cleaning the roller surface which are pressed against each heat roller and cleaning the heat roller. There is a problem that the life is shortened.

In order to solve the above-mentioned problem, the present inventors have made the middle heat roller movable relative to the upper and lower heat rollers, and brought the upper and middle heat rollers into pressure contact with each other to perform the first fixing. When using the second fixing section, the upper heat roller is separated from the middle heat roller when the second fixing unit is used by pressing the middle and lower heat rollers together. An electrophotographic apparatus having a fixing device has been previously proposed (Japanese Patent Application No. 4-51762).

[0005] As shown in FIG.
An upper heat roller 501, a middle heat roller 502 and a lower heat roller 503 each having a built-in heater are provided, and the upper and middle heat rollers 501 and 502 are pressed against each other to form a first fixing unit for full-color copying. , The middle and lower heat rollers 502 and 503 are pressed against each other to form a second fixing portion for monochrome copying. Each of the heat rollers 501 to 503 is configured to transmit rotational force with the middle heat roller 502 as a driving side and the upper and lower heat rollers 501 and 503 as driven sides, and the middle heat roller 502 is driven by the middle heat roller. The rotation is driven by the mechanism 545.

The above-mentioned medium heat roller driving mechanism 545 includes:
Input shaft 531 to which driving force is transmitted from a motor (not shown)
When the second fixing unit for black-and-white copying is used by pressing the middle and lower heat rollers 502 and 503 against each other as shown in FIG.
The clockwise rotation of the input gear 532 is sequentially transmitted to the gear 538 provided through the intermediate gears 533, 534, and 537.
2 rotates clockwise. On the other hand, when the upper and middle heat rollers 501 and 502 are pressed against each other to use the first fixing unit for full-color copying, the solenoid 54
The zero rod portion 540a is actuated, whereby the gear support plate 539 rotates counterclockwise,
The intermediate gears 533, 535, 536,
The gears 538 are sequentially switched to mesh with each other via 537, and as a result, the middle heat roller 502 rotates in the opposite direction.

On the other hand, the middle heat roller 502 is moved up and down by a middle heat roller separation / contact mechanism 546. This mechanism 546 is attached to a cam shaft 518 having an eccentric cam 519 and an end of the cam shaft 518. And an input gear 532c of the spring clutch 542.
Is transmitted through the intermediate gear 541. The spring clutch 542 has two locking projections at positions 180 ° opposite to each other, and the operating portion of the solenoid 543 can be disengaged from these locking projections. This engagement / disengagement operation causes the cam shaft 518 to rotate by 180 °. Accordingly, the support holder (not shown) of the middle heat roller 502 moves up and down in accordance with the direction of the maximum eccentric portion of the eccentric cam 519. As a result, the middle heat roller 502 with respect to the upper and lower heat rollers 501 Is caused to move.

Although not shown, an oil application roller is provided around the upper heat roller 501. When this oil application roller is pressed against upper heat roller 501, oil is applied to the surface of upper heat roller 501. This prevents the toner from adhering (offset) to the roller surface and ensures the releasability of the toner image. In order to prevent the upper heat roller 501 from being worn due to sliding contact between the oil applying roller and the upper heat roller 501, the oil applying roller is configured to be able to move toward and away from the upper heat roller 501.

[0009]

However, in the above configuration, the upper heat roller 501 is
It does not rotate except when it is pressed against and forms the first fixing unit. That is, when the second fixing unit is used, even if the oil application roller is pressed against the upper heat roller 501,
Oil cannot be applied to the entire circumference of the roller 501. Therefore, when the use of the first fixing unit is started, oil application to the surface of the upper heat roller 501 is started, and as a result, the fixing operation is performed in a state where the oil application to the roller surface is insufficient. Easy to do. In addition, when the second fixing unit is used, the oil application roller is held in a state of being separated from the upper heat roller 501. Therefore, after the use of the second fixing unit is continued for a long time, the use of the first fixing unit is stopped. In the case of switching, the temperature of the oil application roller decreases during this time, and as a result, the viscosity of the impregnated oil increases, causing a problem that a uniform oil application state on the roller surface cannot be obtained. ing.

Further, in the above configuration, a dedicated separating / separating mechanism for moving the oil application roller toward and away from the upper heat roller 501 is provided, so that the number of parts is increased, and the apparatus becomes large and complicated. Is to be invited.

Further, in the above, the power supply to the heater incorporated in the unused heat roller is suppressed in accordance with the limitation by the rated power consumption of the copying machine. During the time when the temperature is adjusted by energizing the heaters of the upper and middle heat rollers 501 and 502, the energization of the lower heat roller 503 is suppressed. Another problem is that the second fixing unit cannot be used immediately after the use of the first fixing unit.

[0012]

According to a first aspect of the present invention, there is provided an electrophotographic apparatus having first to third fixing rollers, wherein a first fixing roller and a first fixing roller are provided. A first fixing portion is formed at a pressure contact portion with the second fixing roller.
A second fixing unit is formed at a pressure contact portion between the fixing roller and the third fixing roller, and a fixing device that feeds a sheet conveyed to each fixing unit in a discharge direction by rotation of the fixing roller; (2) In an electrophotographic apparatus, comprising: a fixing unit; and a sheet conveying device configured to convey a sheet on which an unfixed toner image is formed, wherein the first fixing roller includes a color toner image stacked in a plurality of layers. The second fixing roller is made of a material capable of fixing at least a single-layer toner image on the sheet, and the first fixing part is formed as a fixing part for full-color image formation. On the other hand, the second fixing unit is formed as a fixing unit for forming a single-color image, and the separation and contact fixing for forming the first and second fixing units together with other fixing rollers of the first to third fixing rollers. roller Release agent supply means is provided to the first fixing roller so as to be able to move away from and contact the other fixing roller, and supplies a release agent for securing the releasability of the color toner to the first fixing roller to the surface of the first fixing roller. The fixing roller is pressed against another fixing roller to form the first fixing unit and the fixing roller is pressed against another fixing roller to form the second fixing unit. And at this time, separation and holding means for separating the remaining fixing rollers other than the two fixing rollers in the pressed state from the second fixing roller, and the release agent supply means as the first fixing roller.
The image forming apparatus is characterized in that it includes a separation / contact driving unit for separating / contacting the fixing roller, and a fixing roller driving unit for constantly rotating the first fixing roller.

According to a second aspect of the present invention, there is provided an electrophotographic apparatus having first to third fixing rollers, wherein a first fixing section is provided at a press contact portion between the first fixing roller and the second fixing roller. A fixing device for forming a second fixing portion at a pressure contact portion between the second fixing roller and the third fixing roller, and for feeding the sheet conveyed to each fixing portion in a discharge direction by rotation of the fixing roller; In an electrophotographic apparatus having a first fixing unit and a second fixing unit and a sheet conveying device for conveying a sheet on which an unfixed toner image is formed, the first to third fixing rollers are individually provided. The fixing roller supporting member is swingably supported by a fixing roller supporting base, and the first to third fixing rollers together with the other fixing rollers are used for the above-mentioned fixing roller supporting member. Form first and second fixing parts A fixing roller supporting member that supports the detachable fixing roller is provided so as to be detachable from the fixing roller so that the fixing roller can be moved toward and away from the other fixing roller, and is provided near the first and third fixing rollers. A release agent supply unit that supplies a release agent to the surface of the fixing roller with a release agent that ensures toner releasability with respect to the fixing roller; and an adhering matter removal unit that cleans the surface of the fixing roller. The adhering matter removing means presses against the fixing roller forming the first and second fixing portions and separates from the remaining fixing roller not forming the fixing portion. The fixing / contact fixing roller provided on the fixing roller supporting base is pressed against another fixing roller on which the first fixing section is to be formed, and is pressed against another fixing roller on which the second fixing section is to be formed. State and hold on In both cases, there is provided a separation / contact holding means for separating the remaining fixing rollers other than the above both fixing rollers in the pressed state from the second fixing roller / release agent supplying means and the attached matter removing means. And

According to a third aspect of the present invention, there is provided an electrophotographic apparatus having first to third fixing rollers, wherein a first fixing section is provided at a press contact portion between the first fixing roller and the second fixing roller. A fixing device that forms a second fixing portion at a pressure contact portion between the second fixing roller and the third fixing roller, and feeds a sheet conveyed to each fixing portion in a discharge direction by rotation of the fixing roller; In an electrophotographic apparatus including a first fixing unit and a second fixing unit, and a sheet conveying device for conveying a sheet on which an unfixed toner image is formed, the first to third fixing rollers include: The two fixing rollers forming the fixing unit or the second fixing unit are constantly pressed, and the separation fixing roller forming the remaining fixing unit other than the fixing unit together with the other fixing roller in the pressed state is used as another fixing roller. It is provided so that it can move away from and A separation and holding means for holding the separation and fixing roller in a state in which it is pressed against another fixing roller on which a fixing section is to be formed and in a state in which it is separated from another fixing roller which does not form a fixing section. It is characterized by:

[0015]

According to the first aspect of the present invention, the release agent supply means for supplying the release agent to the surface of the first fixing roller is provided so as to be able to move away from the first fixing roller. It is separated from and connected to the first fixing roller by the separating and driving means. Further, when the first and second fixing rollers are pressed against each other, the pressing and holding state is maintained by the separation and holding means, and the third fixing roller is separated from the second fixing roller, while the second and third fixing rollers are separated from each other. When the fixing roller is brought into pressure contact, the pressure contact state is maintained by the separation / contact holding means, and the first fixing roller is separated from the second fixing roller. Further, the first fixing roller is constantly driven to rotate by a fixing roller driving unit.

As described above, since the fixing roller driving means is provided and the first fixing roller is constantly driven to rotate, the release agent supply means is pressed against the first fixing roller by the separation / contact driving means, so that the electrophotographic apparatus is provided. At any time after the power supply is turned on, the release agent supply unit can be heated together with the first fixing roller. Therefore, for example, the viscosity of the release agent impregnated in the release agent supply means can be reduced. Accordingly, the release agent can be uniformly supplied to the surface of the first fixing roller, and the best fixing operation can be performed in the first fixing unit, and a high-quality full-color image can be obtained. Further, since the first fixing roller is constantly rotating and the releasing agent is uniformly supplied to the roller surface, immediately after the second fixing unit for forming a single-color image is used, the second fixing unit for forming a full-color image is immediately used. (1) The use of the fixing unit becomes possible, and the operability of the electrophotographic apparatus can be improved.

According to the second aspect of the present invention, the release agent supplying means and the adhering matter removing means are in pressure contact with the fixing roller forming the first and second fixing sections, and the fixing section is fixed. The fixing roller is provided on the fixing roller supporting base so as to be separated from the remaining fixing roller that is not formed. When the first and second fixing rollers are pressed against each other,
The pressure-contact state is maintained by the separation / contact holding means, and the third fixing roller is separated from the second fixing roller / release agent supplying means and the attached matter removing means, while the second and third fixing rollers are pressed against each other. In this case, the pressure-contact state is maintained by the separation / contact holding means, and the first fixing roller is separated from the second fixing roller / release agent supply means and the attached matter removing means.

As described above, it is possible to separate from and separate from the first and third fixing rollers, respectively, without providing a special driving device or the like in the release agent supplying means and the attached matter removing means. As a result, the number of components can be reduced, so that the size and structure of the fixing device can be reduced, and the cost of the electrophotographic apparatus can be reduced.
In addition, since it can be separated and contacted, the release agent supply means,
Wear and the like of the attached matter removing means and the first and third fixing rollers can be reduced.

According to the third aspect of the present invention, the first
Or the first fixing unit or the second fixing roller of the third fixing roller.
The two fixing rollers forming the fixing section are always in pressure contact with each other, and the separation fixing roller forming the remaining fixing section other than the fixing section together with the other fixing roller in the pressed state is in pressure contact with another fixing roller. When it is done,
While this pressure-contact state is maintained, when the separation-fixing roller is separated from other fixing rollers, the separation state is maintained by separation-holding means.

As described above, when the first and second fixing rollers forming the first fixing section are constantly pressed, the remaining third fixing roller forms the second fixing section when forming the second fixing section. The roller moves away from and close to the roller.
When the second and third fixing rollers forming the fixing unit are constantly pressed against each other, the remaining first fixing roller moves so as to move away from and close to the second fixing roller when forming the first fixing unit. It has become. For this reason, the separating and holding means is simplified and the number of components is reduced, so that the fixing device can be downsized and the structure can be simplified, and the cost of the electrophotographic apparatus can be reduced.

In view of power consumption, the first to third
In the case where the heating of the fixing roller is limited, even when the temperature of one of the two fixing rollers is not adjusted, the temperature of the other fixing roller that is in pressure contact with the other is fixed. The heat can prevent the temperature of the fixing roller whose temperature has not been adjusted from decreasing. Therefore, when the first and second fixing rollers are constantly pressed against each other, the first fixing unit can be used immediately after the use of the second fixing unit, and the second and third fixing rollers are always used. When pressed, the second fixing unit can be used immediately after the use of the first fixing unit, so that the operability of the electrophotographic apparatus can be improved.

[0022]

【Example】

[Embodiment 1] FIGS. 1 to 8 show an embodiment of the present invention.
This will be described below. A full-color copying machine (hereinafter, referred to as an electrophotographic apparatus according to the present embodiment)
As shown in FIG. 3, the copier 1 includes a copier main body 1 and a reverse retransmission unit (not shown) provided below the copier main body 1.

The main body 1 of the copying machine has a document table 3 made of transparent hard glass on the upper surface, and an exposure optical system 4 below the document table 3. This exposure optical system unit 4
A lamp unit 5 that scans a document (not shown) placed on the document table 3 while irradiating the document with light, a plurality of reflecting mirrors 6 for guiding reflected light from the document to the photoconductor 8, A color separation filter 7a of three primary colors of blue, green, and red arranged in the optical path of the reflected light, a lens unit 7,
And a slit (not shown).

The photosensitive member 8 is provided so as to be rotatable in the B direction. A charging charger 9 for charging the surface of the photosensitive member 8 to a predetermined potential is provided on the outer periphery of the photosensitive member 8. 9, an image-to-image eraser (not shown), a black developing tank 1
0, yellow developing tank 11, magenta developing tank 12, cyan developing tank 13, intermediate transfer device 14, cleaning device 15
And the static eliminator 16 are arranged in this order. The developing tanks 11 to 13 store yellow, magenta, and cyan toners, which are complementary colors of the respective color filters in the color separation filter 7a. The black developer tank 10 stores black toner.

The above-mentioned intermediate transfer device 14 presses the transfer belt 17, which can rotate in the direction C, the rollers 18, 19, 20 supporting the transfer belt 17, and the transfer belt 17 against the photosensitive member 8, A first transfer roller 21 for transferring the toner image formed on the surface to the transfer belt 17 is pressed against the roller 20 when the toner image is transferred to the transfer paper (sheet), and the toner image on the transfer belt 17 is transferred onto the transfer paper. A second transfer roller 22 to be driven and a cleaning device 23 for removing residual toner and the like on the surface of the transfer belt 17 are provided.

On the paper supply side of the intermediate transfer device 14, a registration roller 24, a paper supply cassette 25, and a paper supply tray 26 for supplying transfer paper to the intermediate transfer device 14 at a predetermined timing are provided. In the vicinity of the cassette 25 and the paper feed tray 26, paper feed rollers 27, a transport roller 28 and the like are provided.

On the paper discharge side of the intermediate transfer device 14, a suction unit 100 as a sheet transport device for transporting the transfer paper, a fixing device 200, a switching gate 2
9, a paper discharge roller 30 and a paper discharge tray 31 are provided. The switching gate 29 switches the transport direction of the transfer sheet discharged from the fixing device 200 between the direction of the discharge roller 30 and the direction of the re-feed transport path 32 for performing double-sided copying.

The re-sending conveyance path 32 extends to an intermediate tray (not shown) in the reversing re-sending unit, and conveys the transfer sheet processed by the fixing device 200, and transfers the transfer sheet to the toner image. The sheet is discharged onto the intermediate tray with the formed surface facing upward. Transfer paper conveyed by the resending conveyance path 32 is stacked on the intermediate tray, and the transfer paper is
The paper is sent to the re-feeding conveyance path 35 by a paper feed roller (not shown) or the like. The transfer sheet sent from the intermediate tray through the re-feeding conveyance path 35 is turned over and sent to the registration rollers 24.

The suction unit 100 conveys the transfer paper to the fixing device 200 by a conveyer belt that moves around. The suction unit 100 rotates around an end on the paper input side.
It is provided rotatably at an upper position and a lower position. The upper position is a position where the transfer paper can be conveyed to an upper fixing section of the fixing device 200 described later, and the lower position is the fixing device 2.
00 is a position where the transfer paper can be conveyed to the lower fixing unit. The rotation state of the suction unit 100 to the upper and lower positions and the passage of the transfer paper in the suction unit 100 are detected by a suction unit position sensor 120 and a transfer paper sensor 121 described later. . Also, the suction unit 100
The rotation of the conveyor belt to the upper and lower positions and the rotation of the conveyor belt are performed, for example, by a cam unit provided on the lower surface side of the suction unit 100 or a suction unit drive described later provided with a solenoid (both not shown) and the like. This is performed by the mechanism 122.

As shown in FIG. 4, the fixing device 200 includes an upper heat roller 201 as a first fixing roller, a middle heat roller 202 as a second fixing roller, and a third A lower heat roller 203 as a fixing roller is provided. The middle heat roller 202 can move up and down, and is pressed against the upper heat roller 201 and the lower heat roller 203 alternatively. By pressing the middle heat roller 202 against the upper heat roller 201,
This press-contact portion is formed as an upper fixing portion (first fixing portion) which becomes a fixing portion for full-color copying. Further, when the middle heat roller 202 is pressed against the lower heat roller 203, the pressed portion is formed as a lower fixing portion (second fixing portion) serving as a fixing portion for monochrome copying. The upper heat roller 201 is made of silicon rubber, the middle heat roller 202 is made of Teflon, and the lower heat roller 203 is formed on the surface of each heat roller.
Are formed of silicon rubber or other suitable rubber. Note that the surface of the upper heat roller 201 is a very smooth surface in order to obtain high releasability from a three-layer color toner image for obtaining a full-color copy image.

Each of the heat rollers 201 to 203 has a hollow shape, and heater lamps 204 for heating are provided in these hollow portions. In addition, each heat roller 201
Thermistor 2 for detecting the surface temperature around ~ 203
05, a thermostat (not shown) for preventing overheating incorporated in a control circuit for supplying electricity to the heater lamps 204, and a cleaning roller 206 for removing toner and the like attached to the surfaces of the heat rollers 201 to 203. Are provided respectively.

The middle and lower heat rollers 202.2
Around the upper heat roller 201, there are provided peeling claws 207 for peeling the transfer paper from the roller surface. Oil application roller 208
Is provided. This oil application roller 208 applies silicon oil to the surface of the upper heat roller 201,
Adhesion of the color toner to the roller surface, that is, preventing the offset and securing the releasability of the color toner image,
This is for giving gloss to the full-color copy image.

An upper discharge conveyance path 41 is formed between the upper fixing section and the discharge roller 30, and a lower discharge conveyance path 42 is formed between the lower fixing section and the discharge roller 30. . The re-sending transport path 32 branches from the lower discharge transport path 42 and extends downward. The transport direction of the transfer paper discharged from the lower fixing unit is set to the lower discharge transport path at the branch of the transport paths 42 and 32. A switching gate 29 for switching between the path 42 and the retransmission path 32 is provided.

Next, a description will be given, with reference to FIG. 1, of a middle heat roller separation mechanism for moving the middle heat roller 202 up and down to separate the roller 202 from the upper and lower heat rollers 201 and 203.

Upper / middle and lower heat rollers 201/20
Reference numerals 2 and 203 denote upper / middle and lower holders 209 and 21 as fixing roller support members provided at both ends, respectively.
And 0.21 via a bearing (not shown) so as to be rotatable. These upper or lower holders 209-2
11, the cleaning roller 206
Are rotatably mounted in a state of being constantly in contact with the corresponding heat rollers 201 to 203. Each holder 2
Each of 09 to 211 has a connection shaft 21 at the end on the paper output side.
2 are swingably connected to a roller supporting base 213 as a fixing roller supporting base. On the other hand, the ends of the upper and lower holders 209 and 211 on the paper input side are pulled downward and upward by tension springs 214 and 214, respectively. The upper and lower holders 20
The engaging portion 209a
On the other hand, an engaging portion 213a that engages with the engaging portion 209a of the upper holder 209 to restrict downward rotation of the upper holder 209,
The lower holder 2 is engaged with the engagement portion 211a of the lower holder 211.
And a lock portion 213b for restricting the upward rotation of the lock 11.

The oil application roller 208 is rotatably held at one end of a roller holder 215. The roller holder 215 is rotatably connected to a roller support base 213 by a connecting shaft 215a in the vicinity of the central portion, and has a compression spring 216 and an eccentric cam 217 which constitute a separation / contact driving means together with the roller holder 215 at the other end. Are provided.
The compression spring 216 moves the roller holder 215 in a direction in which the oil application roller 208 is separated from the upper heat roller 201.
Is energizing. On the other hand, the eccentric cam 217 is driven and rotated by an oil application roller cam drive mechanism 254 described later, thereby rotating the roller holder 215 against the urging force of the compression spring 216, and moving the oil application roller 208 to the upper heat roller 201. Is to be pressed against.

At the end of the middle holder 210 on the paper input side, an opening 210a opening to the paper input side is formed.
An eccentric cam 219 is provided in the opening 210a. The eccentric cam 219 is formed on the cam shaft 218,
Together with the middle holder 210, it constitutes a separating and holding means. An interposing plate 220 is provided between the eccentric cam 219 and the upper edge portion 210b of the opening 210a.
The end on the paper output side is swingably connected to the middle holder 210 by a connection shaft 221. A screw 222 is screwed into an end portion of the interposing plate 220 on the paper entry side, passing through an upper edge 210b of the opening 210a. A compression spring 223 is arranged between the head of the screw 222 and the upper edge 210b,
The state in which the eccentric cam 219 is sandwiched between the interposed plate 220 and the lower edge 210c of the opening 210a from above and below is maintained. Accordingly, the rotation of the cam shaft 218, that is, the eccentric cam 219, moves the middle holder 210, that is, the middle heat roller 202, in the vertical direction, and thereby separates from the upper and lower heat rollers 201 and 203. The sliding contact between the eccentric cam 219 and the middle holder 210 in this case can be adjusted by rotating the screw 222. The upper and lower heat rollers 201
The separation / contact state of the middle heat roller 202 with respect to the central heating roller 203 is determined by a separation / contact sensor 224.2 provided on the roller support base 213.
It is detected at 25.

The above and below heat rollers 201 and 2
Numeral 03 is driven to rotate by a heat roller driving mechanism 245 as a fixing roller driving unit shown in FIG. The heat roller driving mechanism 245 has an input gear 232 on an input shaft 231 to which a driving force is transmitted from a heat roller driving motor 253 described later. And the intermediate gear 24
One. This intermediate gear 241 is
2 and the gear 238 are always engaged. Accordingly, the rotation of the input gear 232 in the clockwise direction in the figure is transmitted via the intermediate gear 241 and the gear 238 to the upper heat roller 20.
1 is transmitted. As a result, the upper heat roller 201 rotates clockwise, and when the middle heat roller 202 is pressed against this,
Rotates in the counterclockwise direction. As a result, the transfer sheet sent between the heat rollers 201 and 202 is sent toward the sheet discharge roller 30.

On the other hand, the input gear 232 always meshes with a gear 237 provided on the lower heat roller 203. Accordingly, the rotation of the input gear 232 is
Is also transmitted to the lower heat roller 203, whereby the lower heat roller 203 rotates in the counterclockwise direction, and when the middle heat roller 202 is pressed against the lower heat roller 203, the roller 202 rotates clockwise. As a result, the transfer sheet sent between the heat rollers 202 and 203 is sent toward the sheet discharge roller 30 in the same manner as described above.

As described above, the heat roller driving mechanism 2
Reference numeral 45 denotes a configuration in which the upper and lower heat rollers 201 and 203 are set as the driving side, and the middle heat roller 202 is set as the driven side. Further, since the gear 238 of the upper heat roller 201 is always meshed with the input gear 232 via the intermediate gear 241, the gear 238 always rotates clockwise by the driving force from the heat roller driving motor 253. Therefore, when the oil application roller 208 is pressed against the upper heat roller 201 by an oil application roller cam driving mechanism 254 described later, the oil application roller 208 rotates in a counterclockwise direction. As a result, the silicone oil can be applied over the entire circumference of the upper heat roller 201 at any time after the power of the copying machine is turned on.

The cam shaft 218 is driven to rotate by a cam drive mechanism 246 shown in FIG. The cam drive mechanism 246 is configured by meshing an input gear 242c of a spring clutch 242 provided on a cam shaft 218 with the intermediate gear 241. Spring clutch 24
2, two locking projections 242a.2, as shown in FIG.
42b is located at a position facing 180 °, and the locking projections 242a and 242b are attached to the operating portion 24 of the solenoid 243.
3a is detachable. Then, as shown in the figure, when the operating portion 243a engages with one of the locking projections 242b, the maximum eccentric portion of the eccentric cam 219 drives the middle holder 210 downward, and the middle heat roller 202
Moves to the position where the lower fixing section is formed, and the lower heat roller 2
03. On the other hand, when the operating portion 243a engages with the other locking projection 242a as shown in FIG. 7, the maximum eccentric portion of the eccentric cam 219 drives the middle holder 210 upward, and moves the middle heat roller 202 upward. It moves to a position where a fixing section is formed and is pressed against upper heat roller 201. The pressing force of the middle heat roller 202 against the upper and lower heat rollers 201 and 203 can be adjusted by replacing the extension spring 214 or changing the stop position of the eccentric cam 219 shown in FIG.

Further, as shown in FIG. 8, the copying machine is provided with a control device 251 composed of, for example, a microcomputer for controlling the suction unit 100 and the fixing device 200. This control device 251
Are the contact sensors 224 and 225, thermistor 20
5. In addition to the suction unit position sensor 120 and the transfer paper sensor 121, based on input from various input keys and the like,
As described later, the heat roller drive motor 253, the suction unit drive mechanism 122, the solenoid 243, the heater lamp 204, the oil application roller cam drive mechanism 254
And the like. The oil application roller cam drive mechanism 254 has, for example, the same configuration as the cam drive mechanism 246 described above.

In the above configuration, when the power switch (not shown) of the copier is turned on, the heater lamps 204 of the fixing device 200 are turned on, and other predetermined initial operations are performed. Becomes At this time, for example, as shown in FIG. Is done.
Therefore, in the cam drive mechanism 246 of the fixing device 200, as shown in FIG.
2b. The heat roller drive mechanism 24
5, the upper heat roller 201 rotates clockwise and the lower heat roller 203 rotates counterclockwise. The oil application roller 208 is driven by an oil application roller cam drive mechanism 254 to drive the upper heat roller 2.
01, thereby rotating counterclockwise and heated together with the upper heat roller 201. Accordingly, the silicone oil impregnated in the oil application roller 208 is appropriately heated, the viscosity is reduced, and the silicon oil is uniformly applied to the surface of the upper heat roller 201. This state is maintained in the standby state.

Next, a full-color copying operation will be described. When a copy start button (not shown) is turned on after a full-color copy selection key (not shown) is turned on, the control device 251 causes the cam drive mechanism 246 to shift from the state shown in FIG. 24
Solenoid 243 for one of the two locking projections 242b.
After the engagement of the operating portion 243a is released and the spring clutch 242 rotates by 180 °, the operating portion 243a is engaged with the other locking projection 242a as shown in FIG. With this rotation, the eccentric cam 219 is rotated by 180 °, and as shown in FIG. It switches to the pressure contact state. This state is detected by the ON operation of the separation sensor 224 and the OFF operation of the separation sensor 225.
Since the pressing operation of the oil application roller 208 against the upper heat roller 201 has already been performed in the initial operation when the copier is in the standby state, the surface of the upper heat roller 201 Oil is evenly applied.

In the above state, the upper holder 2
09 is slightly pushed counterclockwise by the middle heat roller 202, so that the upper heat roller 201 is held at a position slightly higher than when it is separated from the middle heat roller 202. On the other hand, the lower holder 211
Rotation in the counterclockwise direction by the tension spring 214
The lower heat roller 203 is controlled by the engagement between the engagement portion 211a and the engagement portion 213b.
02 is maintained in a state where it is spaced apart from F.02.

The rotation of the input gear 232 in the heat roller driving mechanism 245 in the clockwise direction causes the upper heat roller 201 to rotate in the clockwise direction and the middle heat roller 202 to rotate in the counterclockwise direction. Further, the suction unit 100 is driven by the suction unit driving mechanism 122 to be rotated to the upper position, and the transport belt is moved around.

When the above operation is completed, the surface of the photosensitive member 8 rotating in the direction B is uniformly charged by the charging charger 9 as shown in FIG. (Not shown) a first scan is performed. The reflected light from the original is radiated through a blue color separation filter 7a and a slit (not shown) to an exposure point on the surface of the photoconductor 8 between the charger 9 and the inter-image eraser (not shown). Then, the photoconductor 8 is exposed to form an electrostatic latent image. Next, the potential of the non-image area on the photoreceptor 8 is removed by the inter-image eraser. Thereafter, the above-described electrostatic latent image is developed with the yellow toner in the yellow developing tank 11 to form a yellow toner image.

Next, the yellow toner image on the surface of the photoconductor 8 is transferred to the first transfer roller 21 to which a high negative voltage is applied.
As a result, the image is transferred onto the transfer belt 17 circulating in the direction C. The residual toner on the surface of the photoconductor 8 is removed by the cleaning device 15, and the residual potential on the surface of the photoconductor 8 is removed by the charge removing device 16.

When the above-described series of operations is completed, the photosensitive member 8 is charged again by the charging charger 9, and the original is scanned by the exposure optical system 4 for the second time. In this case, a green color separation filter 7a is used, and the electrostatic latent image formed on the photoconductor 8 is developed with magenta toner in the magenta developing tank 12. The magenta toner image formed on the surface of the photoconductor 8 is transferred by the first transfer roller 21 so as to be superimposed on the previous yellow toner image on the transfer belt 17. Thereafter, similarly, the third scanning by the exposure optical system unit 4 using the red color separation filter 7a is performed, and the cyan developing tank 13
A cyan toner image is formed on the photoconductor 8 by the development with the cyan toner. This cyan toner image is transferred to the transfer belt 1
7 is transferred onto the magenta toner image.

Next, the second transfer roller 22, which has been separated from the transfer belt 17 in the operation up to now, is pressed against the transfer belt 17, and the second transfer roller 22
Is applied to the transfer paper conveyed from the paper feed cassette 25 or the paper feed tray 26 through the registration rollers 24, the three-layered color toner on the transfer belt 17 is applied. The image is transferred.

The transfer paper on which the color toner image has been transferred is conveyed to the upper fixing portion between the upper heat roller 201 and the middle heat roller 202 in the fixing device 200 by the suction unit 100 rotated to the upper position. . In the upper fixing section, the three-layer color toner image on the transfer paper is heated and melted by the upper and middle heat rollers 201 and 202, the temperature of which is adjusted to a predetermined temperature by the heater lamp 204, and is fixed on the transfer paper. At this time, since silicon oil is supplied from the oil application roller 208 to the surface of the upper heat roller 201, the offset of the color toner image to the upper heat roller 201 is prevented, and the gloss of the full-color copy image on the transfer paper is reduced. Granted. The transfer paper discharged from the upper fixing unit is discharged to the outside of the fixing device 200 through the upper discharge conveyance path 41, and is discharged onto the discharge tray 31 by the discharge rollers 30.

When a predetermined time has elapsed from the end of the above-described full-color copying, the copying machine shifts to a standby state. Therefore, each unit such as the middle heat roller 202 and the suction unit 100 is held in the above-described standby state.

Next, the monochrome copying operation will be described.
When the copy start button (not shown) is turned on after the black-and-white copy selection key (not shown) is turned on from the state in which the full-color copy is possible, the control device 251 causes the cam drive mechanism 246 to operate as shown in FIG. 7, the engagement of the operating portion 243a of the solenoid 243 with the locking projection 242a of the spring clutch 242 is released, and after the spring clutch 242 rotates 180 °,
As shown in FIG. 6, the operating portion 2
43a engage. Therefore, as shown in FIG. 1, the middle holder 210 is driven downward by the maximum eccentric portion of the eccentric cam 219, and the middle heat roller 202 is moved to the lower heat roller 203.
, While the upper heat roller 201 is separated from the middle heat roller 202.

Further, when the input gear 232 of the heat roller driving mechanism 245 rotates clockwise, the lower heat roller 203 rotates counterclockwise and the middle heat roller 202 rotates clockwise. Further, the suction unit 100 is driven by the suction unit driving mechanism 122 to rotate to the lower position, and the transport belt moves around.

When the copy start button is turned on after the black-and-white copy selection key is turned on in the standby state, the operation directly proceeds to the copy operation without performing the above operations.

When the above operation is completed, the surface of the photosensitive member 8 rotating in the direction B is uniformly charged by the charging charger 9 as shown in FIG. (Not shown).
The reflected light from the document is guided to the exposure optical system 4 and irradiated on the photoconductor 8 without passing through the color separation filter 7a and a slit (not shown), and an electrostatic latent image is formed on the photoconductor 8. You. Thereafter, the above-described electrostatic latent image is developed with black toner in the black developing tank 10, and the black toner image thus formed is transferred onto the transfer belt 17,
Further, the image is transferred to transfer paper.

The transfer paper onto which the black toner image has been transferred is transferred to the suction unit 1 which has been rotated downward.
00, the middle heat roller 20 in the fixing device 200
The sheet is conveyed to a lower fixing section between the second heat roller 203 and the lower heat roller 203. In the lower fixing section, the black toner image on the transfer paper is heated and melted when passing between the middle and lower heat rollers 202 and 203, and is fixed on the transfer paper.

Here, in the case of single-sided copying, the above-mentioned switching gate 29 is located at a position for guiding the transfer sheet toward the discharge roller 30, and the transfer sheet passes through the lower discharge conveyance path 42 from the lower fixing section. After passing, the discharge tray 30 is driven by the discharge roller 30.
It is discharged on 1.

On the other hand, in the case of double-sided copying, the switching gate 29 is switched to a position for guiding the transfer sheet in the direction of the re-feeding conveyance path 32, whereby the transfer sheet discharged from the lower fixing unit passes through the re-feeding conveyance path 32. Is sent to the above-mentioned intermediate tray. After that, the transfer paper on the intermediate tray is conveyed in a state of being turned upside down to the registration roller 24 through the retransmission conveyance path 35.

A black toner image for a new document on the document placing table 3 is formed on the inverted transfer paper by the same operation as described above, and this black toner image is heated and melted by the lower fixing unit. Is established. afterwards,
The sheet is guided toward the discharge roller 30 by the switching gate 29, and is discharged onto the discharge tray 31 by the discharge roller 30.

As described above, in this copying machine, the upper and lower heat rollers 201 and 203 are driven on the driving side, and the middle heat roller 202 is driven on the driven side. For this reason, in particular, since the upper heat roller 201 is constantly rotating, the oil application roller 208 is driven by the oil application roller cam drive mechanism 254 at any time after the power of the copying machine is turned on, and the upper heat roller 201 is driven. The upper heat roller 20 is brought into pressure contact with the roller 201.
A rotation operation accompanying the rotation of 1 and an increase in temperature occur. For this reason, the viscosity of the silicone oil impregnated in the oil application roller 208 can be appropriately reduced. As a result, silicone oil can be uniformly applied to the surface of the upper heat roller 201, so that the best fixing operation can be performed in the upper fixing section, and a high-quality full-color copy image can be obtained. Also, since the upper heat roller 201 is constantly rotating and the surface of the roller is uniformly coated with silicone oil, immediately after the use of the lower fixing unit for black-and-white copying, the upper fixing unit for full-color copying is used. The copier can be used, and the operability of the copying machine can be improved.

Embodiment 2 Another embodiment of the present invention will be described below with reference to FIGS. 9 and 10. For the sake of convenience, members having the same functions as those shown in the drawings of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the copying machine of this embodiment, as shown in FIG. 9, the oil application roller 208 is rotatably held by a roller supporting base 313 as a fixing roller supporting base. Therefore, the oil application roller 208 in the fixing device 300 of this embodiment is not provided with the separation / contact driving means such as the oil application roller cam drive mechanism 254 shown in the first embodiment.

An oil application roller 308 impregnated with silicone oil is provided around the lower heat roller 203. The oil application roller 308 applies a small amount of silicone oil to the surface of the lower heat roller 203 to prevent the black toner from adhering to the roller surface, that is, to prevent the offset, thereby ensuring the releasability of the black toner image and the lower heat roller 203. This is for reducing the wear and the like of the roller 203 and improving the durability. In this embodiment, the cleaning rollers 206a and 206b are also rotatably attached to the roller support base 313.

Upper or lower heat rollers 201-203
Are rotatably supported by upper, middle, and lower holders 309, 310, and 311 as fixing roller support members provided at both ends of each of the heat rollers 201 to 203, respectively. Each of the holders 309 to 311 has an end on the paper output side connected to the roller support base 31 by a connecting shaft 312.
3 is swingably connected. Upper and lower holder 30
The ends on the paper entry side of the sheet 9/311 are pulled downward and upward by tension springs 214 and 214, respectively.
On the other hand, while the roller support base 313 is formed, the engaging portion 313a that engages with the engaging portion 309a to restrict the downward rotation of the upper holder 309, and the engaging portion 311a A locking portion 313b that engages and restricts upward rotation of the lower holder 311 is formed.

At the end of the middle holder 310 on the paper entry side, an opening 310a opening to the paper entry side is formed, and an eccentric cam 219 is arranged in this opening 310a. The eccentric cam 219 is formed on the cam shaft 218, and constitutes a separating and holding means together with the middle holder 310. Eccentric cam 21
9 is an upper edge 310b and a lower edge 31 of the opening 310a.
0c. Therefore, the camshaft 21
8, that is, the rotation of the eccentric cam 219,
0, that is, the middle heat roller 202 moves in the vertical direction, and comes into contact with the upper and lower heat rollers 201 and 203.

Then, as shown in FIG.
9, the lower edge 310c of the opening 310a
Is pressed down and the middle holder 310 is driven downward to form a lower fixing portion between the middle and lower heat rollers 202 and 203. The lower holder 311 is pushed by the middle heat roller 202 and slightly clockwise. Therefore, the lower heat roller 203 moves slightly lower than when it is separated from the middle heat roller 202, and is pressed against the oil application roller 308 and the cleaning roller 206b. On the other hand, the upper holder 309
4 is regulated by the engagement between the engagement portion 309a and the engagement portion 313a, so that the upper heat roller 201 is separated from the middle heat roller 202, the oil application roller 208, and the cleaning roller 206a. It is held in the state where it was done.

On the other hand, as shown in FIG.
9, the upper edge 310b of the opening 310a
Is pushed up, the middle holder 310 is driven upward to form an upper fixing portion between the upper and middle heat rollers 201 and 202, and the upper holder 309 is pushed by the middle heat roller 202 and slightly counterclockwise. Since the upper heat roller 201 rotates in the rotation direction,
Is moved slightly higher than when it is separated from it, and is pressed against the oil application roller 208 and the cleaning roller 206a. On the other hand, the lower holder 311
14 rotates in the counterclockwise direction.
The lower heat roller 203 is held in a state where it is separated from the middle heat roller 202, the oil application roller 308, and the cleaning roller 206b. Thus, when the middle heat roller 202 is pressed against the upper and lower heat rollers 201 and 203, the oil application rollers 208 and 3
08 and the cleaning rollers 206a and 206b are in pressure contact with each other, and when they are separated from the middle heat roller 202, they are also kept separated from the oil application rollers 208 and 308 and the cleaning rollers 206a and 206b. I have. Other configurations are the same as those of the first embodiment.

In the above configuration, when a power switch (not shown) of the copying machine is turned on, a predetermined initial operation is performed in the fixing device 300 or the like, and the copying machine enters a standby state. At this time, for example, as shown in FIG.
The lower edge 310c of the opening 310a is pushed down by the maximum eccentric portion of the opening, the middle holder 310 is driven downward, the middle heat roller 202 is pressed against the lower heat roller 203, and the upper heat roller 201 is 20
2 is kept in a state of being separated from the second. At this time, the lower heat roller 203 is held in pressure contact with the oil application roller 308 and the cleaning roller 206b, while the upper heat roller 201 is
Also, it is held in a state separated from the cleaning roller 206a. Further, the lower heat roller 203 rotates counterclockwise, and accordingly, the middle heat roller 202 rotates clockwise, respectively. The suction unit 100 is driven by the suction unit driving mechanism 122 and is turned to a lower position.

Next, a full-color copying operation in this embodiment will be described. After a full-color copy selection key (not shown) is turned on and then a copy start button (not shown) is turned on, as shown in FIG.
19 rotates by 180 °, so that the middle heat roller 2
02 switches to a state of pressing against the upper heat roller 201. At this time, the upper heat roller 201 is also in pressure contact with the oil application roller 208 and the cleaning roller 206a, while the lower heat roller 203 is separated from the middle heat roller 202 and is also separated from the oil application roller 308 and the cleaning roller 206b. Also separate. Further, the upper heat roller 201 rotates clockwise, and accordingly, the middle heat roller 202 rotates counterclockwise. In addition, the suction unit 100
Is driven by the suction unit driving mechanism 122 to be rotated to the upper position, and the transport belt moves around.

When the above operation is completed, the first embodiment is completed.
In the same manner as described above, full-color copying is performed. When a predetermined time has elapsed from the end of the above-described full-color copy, the copying machine shifts to the standby state, and accordingly, the middle heat roller 202 and the suction unit 1
Each means such as 00 is returned to the above-described standby state.

On the other hand, when the black-and-white copy selection key (not shown) is turned on from the state where the full-color copy is possible, and then the copy start button (not shown) is turned on, the eccentric position is shifted to the position shown in FIG. The cam 219 rotates by 180 °, whereby the middle heat roller 202 switches to a state in which the middle heat roller 202 is pressed against the lower heat roller 203. At this time, the lower heat roller 203 is also in pressure contact with the oil application roller 308 and the cleaning roller 206b, while the upper heat roller 201 separated from the middle heat roller 202 is also separated from the oil application roller 208 and the cleaning roller 206a. It is held in the state where it was done. Also, the lower heat roller 203 rotates counterclockwise,
Along with this, the middle heat rollers 202 rotate clockwise, respectively. The suction unit 100 is driven by the suction unit drive mechanism 122 to rotate to a lower position, and the transport belt moves around.

When the copy start button is turned on after the black-and-white copy selection key is turned on in the standby state, the operation directly proceeds to the copy operation without performing the above operations. When the above operation is completed, black-and-white copying is performed as in the first embodiment.

As described above, in this embodiment, the upper and lower heat rollers 201 and 203 are
Is pressed, the oil application roller 208
308 and the cleaning rollers 206a and 206b are in pressure contact with each other, and when they are separated from the middle heat roller 202, they are also kept separated from the oil application rollers 208 and 308 and the cleaning rollers 206a and 206b. I have. in this way,
Even if the oil application rollers 208 and 308 and the cleaning rollers 206a and 206b are not provided with dedicated separation and contact driving means, the switching between the upper and lower heat rollers 201 and 203 can be performed. It is possible to reduce the size, simplify the structure of the device, simplify the structure, and reduce the cost. In addition, since the heat rollers 201 and 203 are not always kept in sliding contact with each other, but are switched to a separated state as appropriate, the oil application rollers 208 and 30
8. Wear of the cleaning rollers 206a and 206b and the upper or lower heat rollers 201 to 203 can be reduced.

In this embodiment, the upper and lower heat rollers 201 and 203 are driven on the driving side,
Although the configuration in which the second heat roller 2 is driven and driven to rotate is described as an example, the same effect can be obtained in a configuration where the middle heat roller 202 is the driving side and the upper and lower heat rollers 201 and 203 are the driven side.

Third Embodiment Still another embodiment of the present invention will be described below with reference to FIGS. For the sake of convenience, members having the same functions as those shown in the drawings of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 11, in the fixing device 400 in the copying machine of the present embodiment, the lower heat roller 203 and the cleaning roller 206 are in contact with each other.
Each is rotatably supported by the lower holder 403.
The lower holder 403 has an end on the paper input side swingably connected to the roller support base 401 by a connection shaft 412, while an end on the paper output side is pulled upward by a tension spring 214. The tension spring 214 urges the lower heat roller 203 so as to be constantly pressed against the middle heat roller 202. Accordingly, the fixing device 400 of the copying machine is used.
Has a configuration in which a lower fixing portion for black-and-white copying is always formed.

On the other hand, the upper heat roller 201 is rotatably held by an upper holder 402 serving as a fixing roller supporting member. While the end on the paper output side is connected to a tension spring 214.
Is pulled downward. Also, the upper holder 40
2, a cam receiving plate 402a is formed at the end portion on the paper input side, and an eccentric cam 219 which is in sliding contact with the cam receiving plate 402a is arranged on the cam receiving plate 402a. The eccentric cam 219 is formed on the cam shaft 218, and constitutes a separation and holding means together with the upper holder 402.
The upper holder 402, that is, the upper heat roller 201 moves in the up-down direction, and causes a separation / contact operation with the middle heat roller 202.

Around the upper heat roller 201, a cleaning roller 206 and an oil application roller 208 are provided. The cleaning roller 206 is disposed on the paper exit side of the upper heat roller 201 and
06 cleaning roller holders 4 provided at both ends
04 is rotatably held. The end of the cleaning roller holder 404 on the paper output side is swingably connected to the upper holder 402 by a connection shaft 412, while the end on the paper input side is pulled downward by a tension spring 214. . An engagement portion 404a is formed at the end of the cleaning roller holder 404 on the paper output side, and the roller support base 401 is engaged with the engagement portion 404a to move the cleaning roller holder 404 downward. A locking portion 401a for restricting rotation is formed.

The oil application roller 208 is disposed on the paper input side of the upper heat roller 201,
08 oil application roller holder 40 provided at both ends
5 rotatably held. The oil application roller holder 405 has its end on the paper input side swingably connected to the upper holder 402 by a connection shaft 412, while its end on the paper output side is pulled downward by a tension spring 214. . An engagement portion 405a is formed at the end portion of the oil application roller holder 405 on the paper input side, and the oil application roller holder 405 is engaged with the engagement portion 405a to be below the oil application roller holder 405. A locking portion 401b for restricting rotation to the right is formed.

The separation / contact operation of the cleaning roller 206 and the oil application roller 208 with respect to the upper heat roller 201 occurs with the separation / contact operation of the upper heat roller 201 with respect to the middle heat roller 202. That is, the eccentric cam 219
Rotates, and the cam receiving plate 402a is pushed down by the maximum eccentric portion of the eccentric cam 219 to rotate the upper holder 402 upward.
5a are locking portions 401a and 40 of the roller support base 401.
1b, the downward rotation of the cleaning roller holder 404 and the oil application roller holder 405 is restricted. As a result, the cleaning roller 206 and the oil application roller 208 are held at positions separated from the upper heat roller 201. On the other hand, the pressing down of the cam receiving plate 402a by the maximum eccentric portion of the eccentric cam 219 is released,
When the upper holder 402 is rotated downward by the tension spring 214, the locking portions 401a and 4a of the roller support base 401 are rotated.
01b and the engaging portions 404a and 405a of the cleaning roller holder 404 and the oil application roller holder 405 are released, whereby the cleaning roller holder 404 and the oil application roller holder 405 rotate downward, and the upper heat It is pressed against the roller 201.

In this embodiment, as shown in FIG. 13, the rotation of the eccentric cam 219 is performed by the suction unit drive motor 104 provided in the suction unit drive mechanism 122. The transmission system of the driving force will be described below.

The suction unit 100 has a configuration in which the conveyor belts 101 are supported by a drive shaft 102 on the paper input side and a driven shaft 103 on the paper output side. The suction unit drive mechanism 122 includes a suction unit drive motor 104, a drive shaft 102, and a driven shaft 10
3, and a cam mechanism (not shown) provided on the lower surface side of the suction unit 100.
Then, as the drive shaft 102 is rotated by the driving force transmitted from the suction unit drive motor 104, the transport belts 101 move around in the direction D in the drawing. Further, the driven shaft 103 is rotatably supported at an end on the paper output side of a suction frame 106 mounted to be vertically movable about the drive shaft 102 side. The rotation of the suction unit 100 to the upper and lower positions depends on the driving force from the suction unit drive motor 104.
0 is transmitted to a cam mechanism or the like provided on the lower surface side of O.

The suction unit drive motor 10
Pulley 10 which rotates in the direction of the arrow in FIG.
5 is transmitted to the pulley 109 provided at one end of the cam shaft 218 via the timing belt 105a, the pulley 107 provided at one end of the roller support base 401, and the timing belt 108. , The camshaft 218 is rotated. The camshaft 218 is provided with a spring clutch 110. The spring clutch 110 has two locking projections 110a and 11
0b at positions 180 ° opposite to each other.
An operating portion 111a of a solenoid 111 provided at one end of a roller support base 401 can be engaged with and disengaged from 10a and 110b. And, the above-mentioned operation part 111a
Is engaged with one of the locking projections 110a, the cam receiving plate 402a is pushed down by the maximum eccentric portion of the eccentric cam 219, the upper holder 402 is driven upward, and the upper heat roller 201 is moved to the middle heat roller 202. On the other hand, when the operating portion 111a is engaged with the other locking projection 110b, the pressing of the cam receiving plate 402a by the maximum eccentric portion of the eccentric cam 219 is released, and the tension spring 214
(FIG. 11) causes the upper holder 402 to rotate downward,
The upper heat roller 201 presses against the middle heat roller 202. The above-described cam drive mechanism 445, upper holder 402, eccentric cam 219, and suction unit drive motor 10
4 constitutes a separation / contact driving means, and the other configuration is the same as that of the first embodiment.

In the above configuration, when the power switch (not shown) of the copier is turned on, the heater lamps 204 of the fixing device 400 are turned on and other predetermined initial operations are performed, and the apparatus enters a standby state. . At this time, as shown in FIG. 11, the cam receiving plate 402a is pushed down by the eccentric cam 219 of the cam drive mechanism 445. As a result, the upper heat roller 201 is separated from the middle heat roller 202, and the cleaning roller 206 and the oil The roller 208 is held in a state separated from the upper heat roller 201.

In the above state, when the full-color copy selection key (not shown) is turned on and then the copy start button (not shown) is turned on, the eccentric cam 219 is turned off.
12, the upper holder 402 is driven downward to press the upper heat roller 201 against the middle heat roller 202, and the cleaning roller 206 and the oil application roller 208 are also moved upward as shown in FIG. The state is switched to the state of being pressed against the heat roller 201. The lower heat roller 203 is held while being pressed against the middle heat roller 202.

The rotation of the middle heat roller driving mechanism (not shown) causes the middle heat roller 202 to rotate counterclockwise and the upper heat roller 201 to rotate clockwise. Further, the suction unit 100 is driven by a cam mechanism (not shown) or the like to be rotated to an upper position, and the transport belts 101 are moved around. When the above operation is completed, a full-color copy is performed as in the first embodiment. When a predetermined time has elapsed from the end of the full-color copy, the copying machine shifts to the standby state.

When the copy start button (not shown) is turned on after the black and white copy selection key (not shown) is turned on from the state where the full color copy is possible, the eccentric cam 219 is rotated by 180 °, The state is switched to the same state as the standby state shown in FIG. 11, and monochrome copying is performed. When the black-and-white copy selection key is turned on in the standby state, the copy operation is started without performing the above switching operation.

As described above, in the copying machine of the present embodiment, the middle and lower heat rollers 202 and 203 are always in pressure contact with each other, and the upper heat roller 201 comes into contact with and separates from the middle heat roller 202. . That is, the lower fixing portions for black and white copying are preferentially formed by the middle and lower heat rollers 202 and 203, and the upper heat roller 201 is pressed against the middle heat roller 202 to form an upper fixing portion during full color copying. For this reason, the heat roller separation / contact mechanism is simplified and the number of components is reduced, so that the apparatus can be downsized and the structure can be simplified, and the cost of the copying machine can be reduced.

Further, since the lower heat roller 203 is constantly pressed against the middle heat roller 202, when the heating of the upper or lower heat rollers 201 to 203 is restricted due to power consumption, for example, when the upper and middle heat rollers 201 to 203 are limited. Even when the temperature of the heat rollers 201 and 202 is adjusted and the temperature of the lower heat roller 203 is not adjusted,
It is possible to prevent the temperature of the lower heat roller 203 from lowering. Therefore, immediately after the use of the upper fixing section for full-color copying, the lower fixing section for black-and-white copying, which is the priority mode, can be used, and the operability of the copying machine can be improved.

In this embodiment, the copying machine in which the middle and lower heat rollers 202 and 203 are constantly pressed and the lower fixing portion for black and white copying is preferentially formed has been described. The same effect can be obtained also in a copying machine in which the upper fixing portion for full-color copying is preferentially formed by always pressing the upper and lower portions 201 and 202.

[0092]

According to the first aspect of the present invention, there is provided an electrophotographic apparatus comprising:
As described above, the first fixing roller is configured to fix a color toner image laminated in a plurality of layers on a sheet, while the second fixing roller is configured to fix at least a single layer toner image on a sheet. The first fixing unit is formed as a fixing unit for full-color image formation, while the second fixing unit is formed as a fixing unit for full-color image formation.
The fixing unit is formed as a fixing unit for forming a single-color image.
Of the third to third fixing rollers, the separating and fixing fixing roller forming the first and second fixing portions together with the other fixing roller is provided so as to be able to separate and move with respect to the other fixing roller.
A release agent supplying means for supplying a release agent for ensuring the releasability of the color toner to the fixing roller to the surface of the first fixing roller is provided so as to be able to move away from and contact with the first fixing roller. (1) While maintaining a state in which it is in pressure contact with another fixing roller in which a fixing section is to be formed and a state in which it is pressed in contact with another fixing roller in which a second fixing section is to be formed, Separation / contact holding means for separating the remaining fixing rollers other than the two fixing rollers from the second fixing roller, separation / contact driving means for separating the release agent supply means from / to the first fixing roller, A fixing roller driving unit that constantly drives the fixing roller to rotate.

Thus, at any point after the power of the electrophotographic apparatus is turned on, the release agent supply means can be heated together with the first fixing roller. Therefore, for example, the viscosity of the release agent impregnated in the release agent supply means can be reduced. Therefore, the release agent can be uniformly supplied to the surface of the first fixing roller, so that the best fixing operation can be performed in the first fixing unit, and a high-quality full-color image can be obtained. Further, since the first fixing roller is constantly rotating and the release agent is uniformly supplied to the roller surface, after the second fixing unit for forming a monochromatic image is used,
The first fixing unit for full-color image formation can be used immediately, and the operability of the electrophotographic apparatus can be improved.

In the electrophotographic apparatus according to the second aspect of the present invention, as described above, the first to third fixing rollers are supported by individual fixing roller supporting members, and the fixing roller supporting members are fixed. A fixing roller that is swingably supported by a roller support base and that supports the separation / contact fixing roller that forms the first and second fixing units together with other fixing rollers of the first to third fixing rollers. The support member is provided so as to be detachable from the fixing roller so that the fixing roller can move toward and away from the other fixing roller. A release agent supply unit that supplies a release agent to be secured to the surface of the fixing roller; and an adhering matter removing unit that cleans the fixing roller surface. You The fixing roller is provided on the fixing roller supporting base so as to be in pressure contact with the fixing roller forming the second fixing portion and to be separated from the remaining fixing roller not forming the fixing portion. Is held in a state in which it is in pressure contact with another fixing roller in which the first fixing section is to be formed and in a state in which it is pressed in contact with another fixing roller in which the second fixing section is to be formed. And a separation / holding means for separating the remaining fixing rollers other than the two fixing rollers in the pressed state from the second fixing roller / release agent supplying means and the attached matter removing means.

Thus, it is possible to separate and contact the first and third fixing rollers, respectively, without providing a special driving device or the like in the release agent supplying means and the attached matter removing means.
Therefore, the number of parts can be reduced, so that the fixing device can be downsized and the structure can be simplified, and the cost of the electrophotographic apparatus can be reduced. Further, since the contact and separation can be performed, it is possible to reduce the wear and the like of the release agent supply unit, the attached matter removing unit, and the first and third fixing rollers.

Further, the electrophotographic apparatus according to the third aspect of the present invention includes the first to third fixing rollers as described above.
The two fixing rollers that form the first fixing unit or the second fixing unit are constantly pressed against each other, and the separation and fixing roller that forms the remaining fixing unit other than the above-described fixing unit together with the other fixing rollers that are in the pressed state is different. The fixing roller is provided so as to be capable of moving away from the fixing roller, and is separated from the other fixing roller in which the fixing roller is pressed against another fixing roller that should form the fixing section and the other fixing roller that does not form the fixing section. This is a configuration including separation and holding means for holding in a state.

Thus, for example, when the first and second fixing rollers forming the first fixing section are constantly pressed, the remaining third fixing roller forms the second fixing section when forming the second fixing section. When the second and third fixing rollers forming the second fixing section are constantly pressed against the fixing roller, the remaining first fixing roller is connected to the first fixing section. Is formed to move toward and away from the second fixing roller. For this reason, the separating and holding means is simplified and the number of components is reduced, so that the fixing device can be downsized and the structure can be simplified, and the cost of the electrophotographic apparatus can be reduced.

Further, from the viewpoint of power consumption, the first to third
In the case where the heating of the fixing roller is limited, even when the temperature of one of the two fixing rollers is not adjusted, the temperature of the other fixing roller that is in pressure contact with the other is fixed. The heat can prevent the temperature of the fixing roller whose temperature has not been adjusted from decreasing. Therefore, when the first and second fixing rollers are constantly pressed against each other, the first fixing unit can be used immediately after the use of the second fixing unit, and the second and third fixing rollers are always used. When pressed, the second fixing unit can be used immediately after the use of the first fixing unit, so that the operability of the electrophotographic apparatus can be improved.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a schematic front view showing a fixing device in a partial cross section during black-and-white copying and in a standby state.

FIG. 2 is a schematic front view showing a partial cross section of the fixing device during full-color copying of the fixing device.

FIG. 3 is a configuration diagram of a copying machine main body in a copying machine including the above-described fixing device.

FIG. 4 is an overall configuration diagram of the fixing device shown in FIG. 1, except for a medium heat roller separating mechanism.

FIG. 5 is a schematic perspective view showing a heat roller driving mechanism and a cam driving mechanism in the fixing device.

FIG. 6 is a schematic front view showing the operation of the cam drive mechanism at the time of monochrome copying.

FIG. 7 is a schematic front view showing the operation of the cam drive mechanism at the time of full-color copying.

FIG. 8 is a block diagram showing a configuration of a main part of a control system provided in the copying machine shown in FIG. 3;

FIG. 9 shows another embodiment of the present invention, and is a schematic front view showing a fixing device in a partial cross section during black and white copying and in a standby state.

FIG. 10 is a schematic front view showing a partial cross section of the fixing device during full-color copying of the fixing device.

FIG. 11 is a schematic front view showing a fixing device in a black and white copy mode and in a standby state in a partial cross section, according to still another embodiment of the present invention.

FIG. 12 is a schematic front view showing a partial cross section of the fixing device during full-color copying of the fixing device.

FIG. 13 is a schematic perspective view showing a configuration of a main part of the fixing device and a suction unit.

FIG. 14 is a schematic perspective view showing a heat roller driving mechanism and a cam driving mechanism in a fixing device of a conventional copying machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Copier main body 100 Suction unit (sheet conveying device) 200 Fixing device 201 Upper heat roller (First fixing roller, Separating / fixing roller) 202 Medium heat roller (Second fixing roller, Separating / fixing roller) 203 Lower heat roller ( Third fixing roller, separation / contact fixing roller) 204 Heater lamp 205 Thermistor 206 Cleaning roller (adhesion removing means) 208 Oil application roller (release agent supplying means) 209 Upper holder (Fixing roller support member) 209a Engaging section 210 Medium holder (Fixing roller support member, separation / contact holding means) 211 Lower holder (fixing roller support member) 211a Engagement section 213 Roller support base (fixing roller support base) 213a Locking section 213b Locking section 214 Extension spring 215 Roller holder (separation) Contact drive means) 216 Compression spring Moving means) 217 Eccentric cam (separation / contact driving means) 219 Eccentric cam (separation / contact holding means) 245 Heat roller driving mechanism (fixing roller driving means) 246 Cam driving mechanism (separation / contact holding means) 251 Controller 254 Oil application roller cam driving Mechanism (separation driving means) 300 Fixing device 309 Upper holder (fixing roller support member) 310 Medium holder (fixing roller support member, separation and holding means) 311 Lower holder (fixing roller support member) 313 Roller support base (fixing roller support) Substrate) 400 Fixing device 401 Roller support base (fixing roller support base) 402 Upper holder (fixing roller support member) 402a Cam receiving plate 445 Cam drive mechanism (separation / contact holding means)

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiaki Masuda 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Hidetoshi Kaneko 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Shuichi Yoshinaka 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Yasunori Kawai 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-2-1633783 (JP, A) JP-A-2-191979 (JP, A) JP-A-2-126271 (JP, A) JP-A-3-134693 (JP, A) JP-A-4 −52674 (JP, A) Japanese Utility Model Application Hei 2-73667 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 13/01 G03G 13/20 G03G 15/01 G03G 15/20

Claims (3)

(57) [Claims] A first fixing roller provided between the first fixing roller and the second fixing roller;
A fixing device in which a fixing portion is formed, a second fixing portion is formed in a pressure contact portion between the second fixing roller and the third fixing roller, and a sheet conveyed to each fixing portion is sent in a discharge direction by rotation of the fixing roller; In the electrophotographic apparatus, the first fixing unit and the second fixing unit each include a sheet conveying device that conveys a sheet on which an unfixed toner image is formed, wherein the first fixing roller includes a plurality of layers. While the color toner image laminated on the sheet can be fixed on the sheet,
The second fixing roller is configured to fix at least a single-layer toner image on a sheet. The first fixing section is formed as a fixing section for full-color image formation, while the second fixing section is formed as a single-color image formation. Of the first and third fixing rollers, the separating and contacting fixing roller forming the first and second fixing units together with the other fixing roller is separated and moved with respect to the other fixing roller A release agent supply means for supplying a release agent for ensuring the releasability of the color toner to the first fixing roller to the surface of the first fixing roller, the release agent supply means being provided so as to be able to move away from and contact with the first fixing roller; Is held in a state where it is pressed against another fixing roller where the first fixing unit is to be formed and a state where it is pressed against another fixing roller where the second fixing unit is to be formed. , Crimped A separation / contact holding unit for separating the remaining fixing rollers other than the above-mentioned two fixing rollers from the second fixing roller, a separation / contact driving unit for separating the release agent supply unit from / to the first fixing roller, And a fixing roller driving unit for constantly driving the first fixing roller to rotate. 2. The image forming apparatus according to claim 1, further comprising a first fixing roller and a third fixing roller.
A fixing device in which a fixing unit is formed, a second fixing unit is formed in a pressure contact portion between the second fixing roller and the third fixing roller, and a sheet conveyed to each fixing unit is sent in a discharge direction by rotation of the fixing roller; In the electrophotographic apparatus, the first fixing unit and the second fixing unit each include a sheet conveying device that conveys a sheet on which an unfixed toner image is formed, wherein the first to third fixing rollers are Each fixing roller support member is supported by an individual fixing roller support member, and the fixing roller support member is swingably supported by a fixing roller support base,
Among the first to third fixing rollers, a fixing roller supporting member that supports the detaching fixing roller that forms the first and second fixing units together with the other fixing roller is such that the detaching fixing roller is connected to the other fixing roller. A release agent supply is provided near the first and third fixing rollers so as to move away from and to move away from the first and third fixing rollers. Means, and an adhering matter removing means for cleaning the surface of the fixing roller, wherein the releasing agent supplying means and the adhering matter removing means are provided with respect to the fixing roller forming the first and second fixing portions. The fixing roller is provided on the fixing roller supporting base so as to be pressed against and separated from the remaining fixing roller that does not form a fixing section, and the separation fixing roller should form a first fixing section. Other fixing ro And a state in which it is pressed against another fixing roller that is to form the second fixing unit, and at this time, the remaining fixing rollers other than the two fixing rollers in the pressed state are removed. An electrophotographic apparatus comprising: a separation / holding unit that separates from a second fixing roller, a release agent supplying unit, and an attached matter removing unit. 3. A fixing device comprising a first fixing roller and a third fixing roller.
A fixing device in which a fixing unit is formed, a second fixing unit is formed in a pressure contact portion between the second fixing roller and the third fixing roller, and a sheet conveyed to each fixing unit is sent in a discharge direction by rotation of the fixing roller; In the electrophotographic apparatus, the first fixing unit and the second fixing unit each include a sheet conveying device that conveys a sheet on which an unfixed toner image is formed. The two fixing rollers that form the first fixing unit or the second fixing unit are constantly pressed against each other, and the separation and fixing roller that forms the remaining fixing unit other than the above-described fixing unit together with the other fixing rollers that are in the pressed state is different. The fixing roller is provided so as to be able to move away from the fixing roller, and is separated from the other fixing roller in which the fixing roller is not in contact with the fixing roller where the fixing roller is to be formed. State and hold on Electrophotographic apparatus characterized in that it comprises a contact holding means.