JP2788378B2 - 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 in which a fixing unit is formed.

[0002]

2. Description of the Related Art As a conventional copying machine as an electrophotographic apparatus, as shown in FIG. 16, a fixing device 914 has heat rollers 914a and 914a as two upper and lower fixing rollers.
14b is known. This copying machine is capable of black-and-white and full-color copying.
The light source lamp 902 scans the original placed on the original placing table 903, and exposes the photosensitive member 905 with the reflected light from the original guided through the filter 904, thereby forming the static electricity formed on the photosensitive member 905. The latent image is transferred to the developing device 9
06 to 908 or the black toner of the developing device 909, and the toner image is transferred via the intermediate transfer belt 910 onto a sheet supplied from any of the sheet cassettes 911 to 913. The power is supplied to the fixing device 914. In the fixing device 914, the upper and lower heat rollers 914a and 914b are pressed against each other, and the toner of the toner image is melted by a fixing unit formed between the heat rollers 914a and 914b, and the toner image is formed. Is fixed on the sheet.

By the way, as described above, in the configuration of the fixing device 914 having only two heat rollers 914a and 914b, the fixing device 914 is not used due to the relationship between the material of the heat rollers 914a and 914b and the material of the sheet adapted thereto. The range of possible sheet types has been reduced.

On the other hand, Japanese Patent Laid-Open Publication No. Sho 51-98036 discloses that a fixing device is provided with three upper, middle and lower heat rollers, and a first fixing portion is formed between the upper and middle heat rollers. And the second between the middle and lower heat rollers.
A fixing device has been proposed in which a fixing unit is formed and a sheet conveying device for conveying a sheet to the first and second fixing units is moved according to the fixing unit to be used. According to such a configuration, by appropriately selecting the material of the upper, middle, and lower heat rollers, the first and second fixing units can be used.
It can handle sheets made of various materials such as paper, labels, mylar, and polycarbonate.

[0005]

However, in a copying machine having a fixing device having three heat rollers as in the latter case, no consideration is given to the processing when a sheet jam occurs in the fixing device. Therefore, not only is it difficult to perform the sheet clogging process, but also because the sheet is torn in the middle due to excessive processing, which leads to a situation where more time is required. Accordingly, it is an object of the present invention to provide a copying machine having an appropriate sheet jam processing mechanism in a configuration having three heat rollers.

[0006]

According to the present invention, there is provided an electrophotographic apparatus comprising:
Fixing rollers are arranged from above to below, and at least one of the three fixing rollers is formed so as to be detachable from and separated from other fixing rollers. The contact / fixing roller is pressed against another fixing roller by a separating / moving unit, and the first fixing unit is provided at the pressure contact portion between the first fixing roller and the second fixing roller, and the second fixing roller and the third fixing roller are provided at the third contact roller.
Forming a second fixing portion at a pressure contact portion with the fixing roller,
A fixing device that feeds the sheet conveyed to each fixing unit in a discharge direction by rotation of a fixing roller, and a movably formed sheet conveyance moving unit are moved by a moving unit position moving unit to the first fixing unit and the second fixing unit. By moving to the section
An electrophotographic apparatus comprising: a sheet conveying device that conveys a sheet on which an unfixed toner image is formed to each fixing unit.
A sheet jam detecting unit for detecting a sheet jam in the first fixing unit and the second fixing unit; and a fixing unit having a sheet jam when the sheet jam is detected by the sheet jam detecting unit. Control means for controlling the separation / contact driving means and the moving part position moving means so that the fixing / separating fixing roller is separated from the other fixing roller with which the pressing roller is pressed and the sheet conveying moving part is moved downward; Are provided.

[0007]

According to the above arrangement, when the sheet jam detecting means detects a sheet jam in the first fixing section or the second fixing section, the separation / contact fixing roller forming the fixing section in which the sheet jam occurs is operated. The sheet is moved away from the other fixing roller that is in pressure contact, and the sheet conveyance moving unit moves downward. Accordingly, in the conventional apparatus in which the above-described operation is not performed, when a sheet jam occurs near the first and second fixing units, for example, the pressure direction of the second fixing roller is changed by a manual operation, Similarly, a manual operation was required to move the sheet conveying / moving unit to open the sheet carry-in side of the first and second fixing units. However, in this apparatus, the pressure on the jammed sheet is automatically increased. At the same time, the space for the sheet jam processing is automatically secured, so that the work for sheet jam processing is facilitated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. A full-color copying machine as an electrophotographic apparatus in the present embodiment (hereinafter simply referred to as a copying machine)
As shown in FIG. 2, the apparatus includes a copying machine main body 1 and a reverse retransmission unit 2 provided below the copying machine main body 1.

As shown in FIG. 3, the copying machine body 1 has a document table 3 made of hard transparent glass on its upper surface, and an exposure optical system 4 below the document table 3. . The exposure optical system section 4 includes a lamp unit 5 that scans a document (not shown) placed on the document table 3 while irradiating the document with light, and a plurality of light guides that guide reflected light from the document to the photoconductor 8. And a lens unit 7 arranged in the optical path of the reflected light.

A charging charger 9 for charging the surface of the photoconductor 8 to a predetermined potential is provided on the outer periphery of the photoconductor 8, and an inter-image eraser (from the charging charger 9 in the rotation direction of the photoconductor 8). (Not shown), 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 above-mentioned intermediate transfer device 14 is provided with the transfer belt 1.
7, rollers 18 and 19 for supporting the transfer belt 17
20, the transfer belt 17 is brought into pressure contact with the photoconductor 8,
A first transfer roller 21 for transferring the toner image formed on the surface to the transfer belt 17, and a second transfer for pressing the toner image on the surface of the transfer belt 17 onto the sheet when the toner image is transferred to the sheet by pressing the roller 20. A roller 22 and a cleaning device 23 for removing residual toner 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 paper to the intermediate transfer device 14 at a predetermined timing are provided. In the vicinity of the paper feed tray 25 and the paper feed tray 26, a paper feed roller 27 and transport rollers 28 are provided.

In the sheet output direction from the intermediate transfer device 14, a suction unit 100 as a sheet conveying device for conveying a sheet, a fixing device 200, a switching gate 29, and a sheet discharge sensor (not shown) for detecting sheet discharge. , A paper discharge roller 30 and a paper discharge tray 31 are provided. The switching gate 29 switches the transport direction of the sheet output from the fixing device 200 between the direction of the discharge roller 30 and the lower transport path 32.

As shown in FIG. 2, the transport path 32 is
It extends to the intermediate tray 33 of the reversing and resending unit 2,
The sheet processed by the fixing device 200 is transported, and the sheet is placed on the intermediate tray 33 with the surface on which the toner image is formed facing upward.
It discharges to the top. The paper sent by the transport path 32 is stacked on the intermediate tray 33, and the paper is sent to the transport path 35 by the paper feed roller 34. The transport path 35 reverses the sheet sent from the intermediate tray 33 and transports the sheet to the registration roller 24.

The above-mentioned suction unit 100 is similar to that shown in FIG.
As shown in FIG. 2, two transport belts 101 are supported by a drive shaft 102 on the paper input side and a driven shaft 103 on the paper output side, and the drive shaft 102 is connected to a belt drive motor 252 described later.
The paper rotates in the direction D, which is the direction in which the paper is conveyed, by being rotated by the power transmitted from the printer. The drive shaft 102 includes a back plate 104 and a front plate 1.
The driven shaft 103 is rotatably supported by a discharge side end of the suction plate 106. The suction plate 106 is mounted so as to be able to move up and down around the drive shaft 102 side.
Is provided. An opening 106a is formed between the conveyor belts 101 in the suction plate 106, and a rod 108a of a sheet sensor 108 serving as a sheet jam detecting unit projects from the opening 106a. A paper jam is detected by an ON operation for more than a time.

A cam shaft 109 is rotatably supported by the rear plate 104 and the front plate 105 below the suction case 107, and a portion of the cam shaft 109 corresponding to the lower surface of the suction case 107. In
Two eccentric cams 110, 110 eccentric in the same direction are provided. An idle shaft 111 is provided on the back plate 104 in the vicinity of the cam shaft 109, and a timing belt 114 is hung between the sprockets 112 and 113 provided on the idle shaft 111 and the drive shaft 102. A gear 115 provided on the idle shaft 111 is engaged with an input gear 116c of a spring clutch 116 provided on the cam shaft 109. Thus, the rotation of the drive shaft 102 is transmitted to the cam shaft 109 via the sprocket 113, the timing belt 114, the sprocket 112, the idle shaft 111, the gear 115, and the spring clutch 116, and the eccentric cams 110 and 11
The lower surface of the suction case 107 is pushed by 0, so that the sheet conveyance moving unit 121 moves up and down.
Note that the sheet conveyance moving unit 121 includes a vertically moving part such as the suction plate 106 and the conveyance belts 101.

The spring clutch 116 is provided as shown in FIG.
As shown in FIG. 6 and FIG.
16b at a position deviated by 180 °.
Actuator 1 of solenoid 117 for 16a and 116b
17a is detachable. Spring clutch 1
16, the operating portion 117a is provided with locking projections 116a and 116b.
When this is engaged, the internal spring is released so that the drive is not transmitted to the camshaft 109. And
As shown in FIG. 5, when the operating portion 117a engages with the locking protrusion 116b, the minimum eccentric portion of the eccentric cam 110 comes into contact with the suction case 107, so that the sheet conveying / moving portion 121 is fixed to the second fixing portion. When the operating portion 117a is engaged with the locking protrusion 116a as shown in FIG. 6 while moving to the lower position as the sheet transport position, the largest eccentric portion of the eccentric cam 110 comes into contact with the suction case 107. Accordingly, the sheet conveyance moving unit 121 is set to move to the upper position as the first fixing unit sheet conveyance position. Note that this upper position corresponds to a fixing device 2 described later.
00 is a position where the sheet can be conveyed to the upper fixing unit as the first fixing unit, and the lower position is a position where the sheet can be conveyed to the lower fixing unit as the second fixing unit in the fixing device 200.

A belt position sensor 118 comprising a microswitch for detecting a state in which the conveyor belts 101 have moved to an upper position and a lower position is provided below the sheet conveyance moving unit 121. The ON operation is performed when the transfer unit 121 is positioned below.

As shown in FIG. 1, the fixing device 200 includes an upper heat roller 201 serving as a first fixing roller, a middle heat roller 202 serving as a second fixing roller, and a third fixing roller provided in parallel in a vertical direction. Lower heat roller 20
3 is provided. The upper heat roller 201 and the middle heat roller 202 are pressed against each other, and the middle heat roller 202 and the lower heat roller 203 are pressed against each other. The upper fixing portion formed at the pressed portion between the upper heat roller 201 and the middle heat roller 202 is used for full-color copying. It becomes the fixing section and the middle heat roller 20
A lower fixing portion formed at a pressure contact portion between the second heat roller 203 and the lower heat roller 203 is a fixing portion for black and white copying. Therefore,
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 made 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 toner image for obtaining a full-color image.

Each of the heat rollers 201 to 203 has a hollow shape, and a heater lamp 20 for heating is provided in the hollow portion.
4 are provided. Around the upper and lower heat rollers 201 to 203, a thermistor 205 for detecting the surface temperature thereof, a thermostat (not shown) for preventing overheating incorporated in a circuit of the heater lamp 204, and a surface of the heat rollers 201 to 203 A cleaning roller 206 for removing toner and the like adhered to the sheet is provided. Further, around the middle and lower heat rollers 202 and 203, peeling claws 207 for peeling the paper from the roller surface are provided.
Is provided, while around the upper heat roller 201,
Oil application roller 208 impregnated with silicon oil
Is provided. This oil application roller 208 applies silicon oil to the surface of the upper heat roller 201,
The purpose is to prevent adhesion of the color toner to the surface of the heat roller, that is, offset, to secure the releasability of the color toner image, and to impart gloss to the full-color copy image.

In order to form the upper fixing section and the lower fixing section, in the present embodiment, the middle heat roller 202 is moved up and down to move the middle heat roller 202 up and down. A mechanism that separates from and contacts 201 and 203 is adopted. Next, this heat roller separation / contact mechanism will be described with reference to FIG.

Upper, middle and lower heat rollers 201 and 20
Reference numerals 2 and 203 denote heat rollers 201 to 20 respectively.
3, upper and middle holders 209.
210 and 211 are rotatably held via bearings (not shown). These upper or lower holders 209-
211, the cleaning roller 20
6 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, it is swingably connected to the roller support base 213. On the other hand, the paper input side ends of the upper and lower holders 209 and 211 are urged downward and upward by a tension spring 214, respectively. The upper and lower holders 209 and 211 have engagement portions 209a and 211a formed at the paper entry side ends, while the roller support base 213 is engaged with the engagement portions 209a to move downward. Locking portion 213a for regulating the rotation of the upper holder 209, and the lower holder 2 which is engaged with the engaging portion 211a and moves upward.
An engagement portion 213b for regulating the rotation of the motor 11 is formed.

The oil application roller 208 is a roller holder 2
15 is rotatably held at one end thereof. The roller holder 215 is pivotally connected to a roller support base 213 in the vicinity of the center by a connection shaft 215a. The other end of the roller holder 215 has a compression spring 216 and an eccentric cam 2.
17 are provided. The compression spring 216 urges the roller holder 215 to rotate in a direction to separate the oil application roller 208 from the upper heat roller 201. On the other hand, the eccentric cam 217 is driven and rotated by an oil application roller cam driving mechanism 254 described later,
The roller holder 215 is rotated against the urging force of the compression spring 216, and the oil application roller 208 is moved to the upper heat roller 2
01.

The middle holder 210 for supporting the middle heat roller
An opening 210a that opens toward the paper input side is formed at an end of the paper input side, and a cam shaft 218 and an eccentric cam 219 are arranged in this opening 210a. The cam shaft 218 is supported by a support member (not shown) and rotates at a fixed position. An interposed plate 220 is provided between the eccentric cam 219 and the upper edge 210b of the opening 210a, and the interposed plate 220 swings at the paper output side end by the roller support base 213 by the connection shaft 221. They are freely connected. The upper edge 21 of the opening 210 a
A screw 222 is screwed through Ob. A compression spring 223 is disposed between the head of the screw 222 and the upper edge 210b. Therefore, the rotation of the cam shaft 218, that is, the eccentric cam 219 causes the middle holder 210, that is, the middle heat roller 202 to move in the vertical direction, and comes into contact with 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 contact state of the middle heat roller 202 with respect to the upper and lower heat rollers 201 and 203 is determined by the separation sensor 2 provided on the roller support base 213.
24 and 225. That is, when the middle heat roller 202 and the upper heat roller 201 are in contact with each other, the separation sensor 224 is turned on. On the other hand, when the middle heat roller 202 and the lower heat roller 203 are in contact, the separation sensor 225 is set. Is turned on.

The above and below heat rollers 201 and 2
03, the middle heat roller 202 is driven and the upper and lower heat rollers 201 and 203 are driven. The middle heat roller 202 and the cam shaft 218
Are driven by a heat roller driving mechanism 245 and a cam driving mechanism 246 shown in FIG.

The heat roller driving mechanism 245 is connected to the input shaft 2 to which the driving force is transmitted from the heat roller driving motor 253.
31 has an input gear 232, and between the input gear 232 and a gear 238 provided on the middle heat roller 202,
Gears 233 to 237 are provided. Gears 234 to 236
As shown in FIGS. 10 and 11, the gear 234 is rotatably supported by a gear support plate 239 that rotates about a gear 233. The gears 234 and 235 are always meshed with the gear 233. An operation protrusion 239a is formed on the gear support plate 239, and the rod 240a of the solenoid 240 is connected to the operation protrusion 239a.

As shown in FIG. 7, when the middle heat roller 202 is pressed against the lower heat roller 203 as shown in FIG.
a is controlled to advance. In this case, the gear support plate 239 rotates clockwise and the gear 234
The gear 236 separates from the gear 237.
Therefore, the rotation of the input gear 232 in the clockwise direction is transmitted to the middle heat roller 202 via the gears 233, 234, 237, 238, and the middle heat roller 202 rotates clockwise and the lower heat roller 203 rotates. The paper rotates in the counterclockwise direction, and the paper between the heat rollers 202 and 203 is sent out toward the paper discharge roller 30. The solenoid 240 is connected to the middle heat roller 2 as shown in FIG.
11 is pressed against the upper heat roller 201, FIG.
As shown in (2), the rod portion 240a is controlled to retreat. In this case, the gear support plate 239 rotates counterclockwise, the gear 236 meshes with the gear 237, and the gear 234 separates from the gear 237. Therefore, the rotation of the input gear 232 in the clockwise direction is controlled by the gears 233, 235.2,
36, 237 and 238 to the middle heat roller 202, the middle heat roller 202 rotates counterclockwise and the upper heat roller 201 rotates clockwise, and the paper between the two heat rollers 202 Is sent out toward the paper discharge roller 30.

In the cam drive mechanism 246, as shown in FIG. 9, an input gear 232 meshes with a gear 241, and this gear 241 meshes with an input gear 242c of a spring clutch 242 provided on a cam shaft 218. I have. The spring clutch 242 is shown in FIGS.
As shown in FIG. 3, two locking projections 242a and 242b are provided at positions shifted by 180 °, and these locking projections 242a and 242b are provided.
The operating part 243a of the solenoid 243 can be disengaged from the 242b. And the above-mentioned operation part 243a
12, when engaged with the locking projection 242b, the maximum eccentricity of the eccentric cam 219 causes the middle holder 2
10 is driven downward to move the middle heat roller 202 to the lower fixing unit position as the second fixing unit position pressed against the lower heat roller 203, while the operating unit 243a moves to the lower fixing unit position in FIG.
As shown in FIG. 3, when the middle holder 210 is engaged with the locking projection 242 a, the largest eccentric portion of the eccentric cam 219 drives the middle holder 210 upward, so that the middle heat roller 202 is pressed against the upper heat roller 201. It moves to the upper fixing unit position as the fixing unit position. The middle heat roller 202 with respect to the upper and lower heat rollers 201 and 203
Can be changed by replacing the tension spring 214 shown in FIG. 11 or changing the stop position of the eccentric cam 219.

Further, as shown in FIG.
The control unit 251 includes, for example, a microcomputer for controlling the suction unit 100 and the fixing device 200. The control device 251 is provided with a heat roller driving motor 253, based on the input from the belt position sensor 118, the paper sensor 108, the separation / contact sensors 224 and 225, and various input keys and the like, as described later. Belt drive motor 252, solenoid 1
17, 240, 243, the heater lamp 204, the operation of the oil application roller cam drive mechanism 254, and the like. The oil application roller cam drive mechanism 254 has the same configuration as the drive mechanism of the eccentric cam 110 in the suction unit 100, for example.

In the above configuration, first, a full-color copying operation in a copying machine 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 2
Under the control of 51, in the heat roller driving mechanism 245, as shown in FIG. 11, the rod portion 240a of the solenoid 240 retreats, and the gear 236 meshes with the gear 237, while the gear 234 separates from the gear 237. Therefore,
The clockwise rotation of the input gear 232 causes the middle heat roller 202 to rotate counterclockwise and the upper heat roller 201 to rotate clockwise. Further, the oil application roller 208 is pressed against the upper heat roller 201.

In the suction unit 100, as shown in FIG. 6, an operating portion 117a of a solenoid 117 is engaged with a locking projection 116a of a spring clutch 116. Accordingly, the sheet conveying / moving unit 121 is driven upward by the maximum eccentric portion of the eccentric cam 110 and is held at the upper position. This state is caused by the O
It is detected by the FF operation.

Thereafter, as shown in FIG. 3, the surface of the photoconductor 8 rotating in the direction B is uniformly charged by the charging charger 9 and the first scanning of the original on the original table 3 by the exposure optical system unit 4. Is performed. The reflected light from the original is
The light is irradiated to an exposure point on the surface of the photoconductor 8 between the charger 9 and the inter-image eraser (not shown) via a blue color separation filter (not shown) and a slit (not shown). 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 electrostatic latent image is developed by the yellow developing tank 11 to form a yellow toner image.

Next, the yellow toner image on the surface of the photoreceptor 8 is transferred to the transfer belt 17 circulating in the direction C by the first transfer roller 21 to which a negative high voltage is applied. 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 unit 4 for the second time. In this case, a green color separation filter 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 is performed, and the cyan toner image is developed on the photoconductor 8 by the development with the cyan toner in the cyan developing tank 13. It is formed. This cyan toner image is transferred onto the magenta toner image on the transfer belt 17.

Next, the second transfer roller 22, which has been separated from the transfer belt 17 in the above operation,
7, and a negative voltage higher than the surface potential of the transfer belt 17 is applied to the second transfer roller 22, so that the second transfer roller 22 is conveyed from the sheet cassette 25 or the sheet tray 26 via the registration roller 24. The three-layer toner image on the transfer belt 17 is transferred to the paper.

The sheet on which the toner image has been transferred is conveyed by the conveying belts 101 of the suction unit 100 to the upper fixing section formed at the press contact portion between the upper heat roller 201 and the middle heat roller 202. In the upper fixing section, the three-layer color toner image on the paper is heated and melted by the upper and middle heat rollers 201 and 202, and is fixed on the paper. At this time, the upper heat roller 2
Since 01 is supplied with silicone oil from the oil application roller 208, offset of the toner image to the upper heat roller 201 is prevented, and gloss is given to the full-color toner image on the paper.

Next, the sheet discharged from the fixing device 200 is discharged onto a discharge tray 31 by a discharge roller 30. At this time, the discharge of the sheet is detected by a sheet discharge sensor.

Next, the black-and-white copying operation of the copying machine will be described. When the copy start button 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 heat roller driving mechanism 245 is controlled by the control device 251 as shown in FIG. As shown, the rod portion 240 of the solenoid 240
a advances and the gear 234 meshes with the gear 237,
The gear 236 moves away from the gear 237. Accordingly, the rotation of the input gear 232 in the clockwise direction causes the middle heat roller 202 to rotate in the clockwise direction and the lower heat roller 203 to rotate.
Rotates counterclockwise. The oil application roller 208 is separated from the upper heat roller 201.

In the suction unit 100, the operating portion 1 of the solenoid 117 with respect to the locking projection 116a of the spring clutch 116 is changed from the state shown in FIG.
17a is released, and then, as shown in FIG.
The operating portion 117a is engaged with the locking projection 116b.
Therefore, the sheet transporting section 121 rotates downward and is held at the lower position.

Thereafter, the surface of the photoconductor 8 is uniformly charged by the charging charger 9, and the exposure optical system 4 scans the original on the original table 3. The reflected light from the original is guided to the exposure optical system unit 4 without passing through the color separation filter and the slit, and is irradiated on the photoconductor 8.
An electrostatic latent image is formed on the image. Thereafter, the above-described electrostatic latent image is developed by the black developing tank 10, and the black toner image thus formed is transferred to the transfer belt 17 and further transferred to paper.

The sheet on which the toner image has been transferred is conveyed by the conveying belts 101 of the suction unit 100 to the lower fixing section formed at the press contact portion between the middle heat roller 202 and the lower heat roller 203, where the toner image is transferred. Is fixed on the paper.

Here, in the case of one-sided copying, the switching gate 29 operates so as to guide the sheet toward the discharge roller 30, and the sheet discharged from the fixing device 200 is discharged by the discharge roller 30. The paper is discharged onto the paper tray 31.

On the other hand, in the case of double-sided copying, the switching gate 29 operates so as to guide the sheet in the direction of the conveyance path 32, and the sheet discharged from the sheet discharge roller 30
Is discharged onto the intermediate tray 33. Thereafter, the paper on the intermediate tray 33 is transported by the paper feed roller 34 to the transport path 35.
And is reversed by the transport path 35 to reach the registration roller 24.

Next, the surface of the photoreceptor 8 is charged
The scanning is performed by the exposure optical system unit 4 on the document placed on the document placing table 3 upside down.
Next, a toner image is transferred to the back surface of the sheet by the same operation as described above, and the toner image is fixed on the sheet by the lower fixing unit. Thereafter, the sheet is guided toward the sheet discharge roller 30 by the switching gate 29, and is discharged onto the sheet discharge tray 31 by the sheet discharge roller 30.

The operation of the suction unit 100 when a paper jam is detected by the paper sensor 108 during full-color copying and black-and-white copying will be described with reference to the flowchart of FIG. When the paper sensor 108 is turned ON for a predetermined time or more and detects a paper jam (S1),
It is determined whether the copy is a full color copy or a black and white copy (S
2). In the case of full color copy, S3 is executed,
In the case of monochrome copying, S8 is executed. Note that S1
If no paper jam is detected in step S11, a normal fixing process is performed (S11).

In S2, when it is determined that full color copying is being performed, and S3 is executed, the upper heat roller 20
The middle heat roller 202 that has been in pressure contact with 1 is separated from the upper heat roller 201 and is pressed into contact with the lower heat roller 203. The downward movement of the middle heat roller 202 is achieved by transmitting the driving force of the heat roller driving motor 253 via the cam mechanism 246 to rotate the spring clutch 242 and to operate the operating section 24 of the solenoid 243.
3a is connected to the locking projection 242a of the spring clutch 242.
From the locking projection 242b.

Further, from the upper position where the sheet transporting / moving unit 121 transports the sheet to the upper fixing unit for color copying,
The sheet is moved to a lower position where the sheet is conveyed to the lower fixing section for monochrome copying (S4). The movement of the sheet conveying / moving unit 121 to such a lower position applies the driving force of the belt driving motor 252 to the driving shaft 102, the sprocket 113, the timing belt 114, the sprocket 112, and the idle shaft 1.
11, the transmission is transmitted to the camshaft 109 via the gear 115 and the spring clutch 116, thereby rotating the spring clutch 116 to move the operating portion 117a of the solenoid 117 to the locking projection 116a of the sprig clutch 116.
And is engaged with the locking projection 116b.

Thereafter, when the paper sensor 108 is turned off and the elimination of the paper jam is detected (S5), the middle heat roller 202 is again pressed against the upper heat roller 201 (S5).
6) The sheet conveying / moving unit 121 is moved to the original upper position (S7), and normal processing is performed (S11). In addition,
The upward movement of the middle heat roller 202 is achieved by transmitting the driving force of the heat roller drive motor 253 via the cam mechanism 246 to rotate the spring clutch 242 and to move the operating portion 243a of the solenoid 243 to a spring. This is performed by an operation of separating from the locking projection 242b of the clutch 242 and engaging with the locking projection 242a.

On the other hand, if it is determined in S2 that black-and-white copying is being performed and S8 is executed, the lower heat roller 20
The middle heat roller 202 that has been in pressure contact with 3 is separated from the lower heat roller 203 and is in pressure contact with the upper heat roller 201.

Thereafter, when the paper sensor 108 is turned off and the elimination of the paper jam is detected (S9), the middle heat roller 202 is again pressed against the lower heat roller 203 (S9).
10) Normal processing is performed (S11).

As described above, in the copying machine, when a paper jam occurs in the fixing unit during the copying operation, the middle heat roller 202 separates from the heat roller forming the fixing unit, and the lower heat roller forms the fixing unit. While being pressed against the heat roller, the sheet conveying / moving unit 121 is lowered to a lower position to open the paper entry side of the fixing unit where the paper jam has occurred, to secure a space for paper jam processing, The pressure between them is released. Moreover, it is performed automatically. Therefore, the paper jam processing can be easily performed, and the paper is not broken in the middle as in the related art, and the processing does not require much time.

The fixing device 200 is arranged such that the upper and lower heat rollers 201 and 203 are
May be moved toward and away from each other. In this case,
For example, the upper and lower heat rollers 201 and 203 are driven in the direction of pressing against the middle heat roller 202 by a compression spring or a tension spring, while the upper and lower heat rollers 201 and 203 are moved by the eccentric cams.
2 can be separated.

The movement of each of the heat rollers 201 to 203 can be performed by means other than the above eccentric cam, for example, a solenoid.

In this embodiment, the middle heat roller 202 is a drive roller and the upper and lower heat rollers 201
Although 203 is a driven roller, the middle heat roller 202 is a driven roller, and the upper and lower heat rollers 201
203 may be a drive roller. In this case, the heat roller driving mechanism 245 connects the upper and lower heat rollers 2.
01 and 203 are provided individually.

Further, the sheet sensor 108 provided on the upper surface of the suction unit 100 is used as the sheet jam detecting means in the present embodiment. For example, a plurality of sheet detecting sensors provided in the copying machine main body 1 are used. By setting the time required for the fixing process in advance using a sheet discharge sensor, it is also possible to detect a paper jam.

Further, the suction unit 10 of the present embodiment
0, the sheet transport moving unit 121 moves only to the upper position and the lower position, but is not limited to this. For example, the sheet transport moving unit 121 may be moved further below the lower position. Accordingly, a configuration in which the paper jam processing is more easily performed can be achieved.

[0057]

As described above, in the electrophotographic apparatus of the present invention, the first to third three fixing rollers are arranged from above to below, and at least one of these three fixing rollers is provided. A roller is formed so as to be able to be separated from and brought into contact with another fixing roller, and the separation and fixing roller formed so as to be able to be separated is brought into pressure contact with another fixing roller by means of separation and moving means.
The first fixing portion is provided at the pressure contact portion between the fixing roller and the second fixing roller, and the second fixing portion is provided at the pressure contact portion between the second fixing roller and the third fixing roller.
A fixing device that forms a fixing unit and feeds the sheet conveyed to each fixing unit in the discharge direction by rotation of the fixing roller, and a movably formed sheet conveyance moving unit are moved by the moving unit position moving unit. An electrophotographic apparatus comprising: a sheet conveying device configured to convey a sheet having an unfixed toner image formed on each fixing unit by moving the fixing unit to the first fixing unit and the second fixing unit; Fixing unit and second
A sheet jam detecting unit for detecting a sheet jam in the fixing unit, and the separation / contact fixing roller forming a fixing unit in which the sheet is jammed are pressed when the sheet jam is detected by the sheet jam detecting unit. Control means for controlling the separation / contact driving means and the moving part position moving means is provided so as to be separated from other fixing rollers and so that the sheet conveying moving part moves downward. .

Thus, when a sheet jam occurs near the first fixing unit and the second fixing unit, a space for sheet jam processing is automatically secured on the sheet conveying side of the fixing unit where the sheet jam has occurred. In addition, since the pressure on the jammed sheet is automatically released, there is an effect that the jamming of the sheet can be easily performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration near a fixing device in a copying machine according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of the copying machine.

FIG. 3 is an enlarged view of a copying machine main body of the copying machine.

FIG. 4 is a perspective view of a suction unit provided in the copying machine.

FIG. 5 is a schematic front view showing a state in which a sheet conveyance moving unit of the suction unit is held at a lower position.

FIG. 6 is a schematic front view showing a state in which a sheet conveyance moving unit of the suction unit is held at an upper position.

FIG. 7 is a schematic front view showing a fixing device in black and white copying in the copying machine in a partial cross section.

FIG. 8 is a schematic front view showing, in partial cross section, a fixing device at the time of full color copying in the copying machine.

FIG. 9 is a schematic perspective view showing a heat roller driving mechanism and a cam driving mechanism in the fixing device.

FIG. 10 is a schematic front view showing the operation of the heat roller driving mechanism during black-and-white copying.

FIG. 11 is a schematic front view showing the operation of the heat roller driving mechanism during full-color copying.

12 is a schematic front view showing the operation of the cam drive mechanism shown in FIG. 9 during black and white copying.

FIG. 13 is a schematic front view showing the operation of the cam drive mechanism shown in FIG. 9 during full-color copying.

FIG. 14 is a block diagram showing a configuration of a main part of a control system provided in the copying machine.

FIG. 15 is a flowchart showing a process when a paper jam occurs under the control of a control device in the copying machine.

FIG. 16 is an overall configuration diagram showing a conventional copying machine.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 suction unit (sheet conveying device) 108 paper sensor (sheet jam detection unit) 118 belt position sensor 121 sheet conveying moving unit 200 fixing device 201 upper heat roller (first fixing roller) 202 medium heat roller (second fixing roller / separation) Contact roller) 203 lower heat roller (third fixing roller) 251 controller 252 belt drive motor 253 heat roller drive motor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomiyuki Ishikawa 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-51-98036 (JP, A) JP-A-2 -191979 (JP, A) JP-A-2-1633783 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/20

Claims (1)

(57) [Claims] A first fixing roller and a third fixing roller are disposed from above to below, and at least one of the three fixing rollers is detachable from and separate from other fixing rollers. The detachable fixing roller formed so as to be detachable is pressed against another fixing roller by a separating and moving means, and the first fixing roller is pressed into contact with 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; The sheet conveyance moving unit formed so as to be movable is moved to the first fixing unit and the second
An electrophotographic apparatus comprising: a sheet conveying device configured to convey a sheet on which an unfixed toner image is formed to each fixing unit by moving the fixing unit to a fixing unit. A sheet jam detecting means for detecting a sheet jam in the sheet jamming portion, and when the sheet jam is detected by the sheet jam detecting means, the separation / fixing roller forming the fixing portion causing the sheet jam is in pressure contact with the sheet. Control means for controlling the separation / contact driving means and the moving part position moving means so as to be separated from the fixing roller and so that the sheet conveying moving part moves downward. Electrophotographic equipment.