JP2001109315A - Electrophotographic recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To release and restore the press-contact between a heating roller and a pressure roller in a fixing device at the time of transportation and at the time of maintenance work with the small number of parts. SOLUTION: This recorder is provided with a pressure release lever 36 equipped with a cam 36a and a tilting operation part 36b for releasing the press-contact of the pressure roller 14 in front tilt and back tilt states, and restoring a press-contact state in a neutral state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording device, and more particularly, to a fixing device.

[0002]

2. Description of the Related Art An electrophotographic recording apparatus forms an electrostatic latent image by exposing a photosensitive member having a uniformly charged surface with a recorded image, and developing the electrostatic latent image with a developer to form a toner image. After the toner image is transferred to a recording sheet, the toner image is fixed on the recording sheet and discharged outside the apparatus.

Generally, a photosensitive belt or a photosensitive drum is used as a photosensitive member. The photoreceptor is driven so as to rotate at a constant speed, so that the surface is uniformly charged at a position facing the charger, and the uniformly charged surface is opposed to the exposure device to emit a light image or a laser beam. Irradiation forms an electrostatic latent image on the surface, and the surface on which the electrostatic latent image is formed is opposed to a developing device to develop the electrostatic latent image with a developer to form a toner image.

In an electrophotographic recording apparatus for recording a color image, an electrostatic latent image formed by exposure is formed separately for yellow, magenta, cyan, and black, and a developing device converts the electrostatic latent image into a toner of a corresponding color. Develop with. The toner images of each color are transferred so as to be superimposed on an intermediate transfer member (intermediate transfer drum) to complete a color toner image.

The recording paper on which the toner image is to be transferred is pulled out of the paper cassette, is brought into contact with a registration roller and waits, is fed out in synchronization with the conveyance timing of the completed toner image, and is transferred to the surface of the intermediate transfer body at the position of the transfer device. The transfer is performed from the intermediate transfer member to a recording sheet by contact.

The fixing of the toner image on the recording paper is performed by a heat fixing device using a heating roller (heat roller) and a pressure roller (backup roller). The heating roller and the pressure roller are rotated in a state in which a pressure contact portion (nip) is formed by pressing, and the recording paper on which the toner image is transferred is passed between the two rollers (nip) so as to pass the toner. Melts and fixes on recording paper.

The recording paper on which the toner image has been fixed is discharged outside the apparatus through a paper discharge roller, or drawn into a recording paper reversing path for recording on the back surface. In the recording paper reversal path,
The conveyance direction of the recording paper is reversed (the rear end is made to be the front end), and the front end is conveyed again to the position of the transfer device, whereby the back surface of the recording paper is brought into contact with the front surface of the intermediate transfer body, and Transfer the image. Then, the recording paper having the toner image transferred to the rear surface is again fixed to the recording paper through the fixing device, and then discharged outside the apparatus through a discharge roller.

As the recording paper, plain paper is generally used, but sometimes a transparent synthetic resin OHP sheet is used.

[0009]

A fixing device in such an electrophotographic recording apparatus is configured such that a heating roller and a pressure roller are pressed against each other and rotated in a state where a nip is formed, and a recording sheet passing between the rollers is provided. By heating and pressurizing the toner image, the toner image is melted and fixed on recording paper. Therefore, if the rotation of both rollers is stopped for a long period of time, the press contact portion is permanently deformed. Then, when permanent deformation occurs in the roller, in the subsequent fixing operation, unevenness in pressure and heating occurs in this permanently deformed portion, causing uneven fixing.

In the fixing device, in order to prevent permanent deformation of the pressure contact portion of the roller, the roller is stopped and does not rotate from the time of manufacture until the user starts using the roller. Since the length is undefined, during production (shipment), the pressure release piece is inserted to release the bearing of the pressure roller to release the pressure contact. At the start of use, the pressure release piece is removed to allow pressure contact. ing.

The fixing device is a portion where paper jam is likely to occur, and is provided with a pressure releasing lever for releasing the pressure contact between the rollers in order to remove the recording paper sandwiched between the rollers during maintenance work. I have. The pressure release lever can be tilted in the pressure release direction when the paper discharge cover is opened to release the pressure contact, and when the paper discharge cover is closed in a state where it is forgotten to return, the pressure release lever is released by the paper discharge cover. Is pushed back to return both rollers to the pressed state.

Therefore, the fixing device of the electrophotographic recording apparatus requires a pressure release piece and a pressure release lever to release the pressure contact between the heating roller and the pressure roller and return the pressure roller to the pressure contact state, thus increasing the number of parts. And uneconomical.

The fixing device is fixed to the frame of the electrophotographic recording device by screwing. However, since the fixing screw has a structure in which the fixing screw can be attached and detached from a lateral side of a rear portion of the body, assembly, maintenance and replacement are performed. Attach / detach work is troublesome.

An object of the present invention is to realize the release of pressure contact and the pressure contact between the heating roller and the pressure roller of the fixing device during transportation and maintenance work with a small number of parts.

Another object of the present invention is to facilitate the work of attaching and detaching the fixing device.

[0016]

According to the present invention, there is provided a fixing device for fixing a recording sheet on which a toner image has been transferred by passing the recording sheet between a heating roller and a pressure roller rotating in a pressure-contact state, and rotating the fixing member backward. An electrophotographic recording apparatus having a pressure release lever for operating the pressure roller against the heating roller and releasing the pressure, wherein the pressure release lever is tilted forward. And a cam and a tilting operation unit that release the pressure contact of the pressure roller in the backward tilt state and bring the pressure roller into the contact state in the neutral state.

The pressure release lever is capable of tilting rearward when the discharge cover is rotated rearward and opened, and is pressed against the discharge cover when the discharge cover is closed while tilted rearward. Being returned to a neutral state.

Further, the fixing device is provided with a detachable cleaning roller that contacts the heating roller, and the pressure release lever can be tilted forward with the cleaning roller removed. At the time of shipment, it was tilted forward.

Further, the present invention comprises a fixing device for fixing the recording paper on which the toner image has been transferred by passing the recording paper between a heating roller and a pressure roller rotating in a pressure-contact state, and fixing the fixing device to a frame. In the electrophotographic recording apparatus mounted on the apparatus mounting portion from above and fixed with set screws, the set screw is arranged along the side surfaces of both end covers and screwed to the fixing device mounting portion. I made it.

The set screw has a length exceeding the height of the end cover, is disposed in a recess formed on the outer surface of the end cover so as to extend in the vertical direction, and its head projects upward. So housed.

[0021]

FIG. 1 is a longitudinal sectional side view showing the basic structure of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention. The color electrophotographic recording apparatus uses a photosensitive belt 1 such that it rotates on a vertically long orbit at a constant speed.
Is uniformly charged by the charger 2 disposed around the rotation orbit, and is exposed by the exposure device 3 to form an electrostatic latent image corresponding to each color.

In the exposure apparatus 3 of the laser beam type, the light emission of the laser diode is controlled to flicker in accordance with the recording data, and the emitted laser beam is deflected by a rotating mirror so that the surface of the photosensitive belt 1 is exposed. Exposure is performed so as to repeatedly scan in a direction perpendicular to the direction of rotation of.

The electrostatic latent image formed on the surface of the photosensitive belt 1 is transferred to a developing device 4C of the developing device 4 corresponding to the electrostatic latent image.
(Cyan), 4M (magenta), 4Y (yellow), 4
By causing K (black) to advance and causing the developer carried on the developing roller to act on the photosensitive belt 1 to perform development, a toner image of each color is formed on the surface of the photosensitive belt 1.

The toner image of each color is transferred to the photosensitive belt 1
The toner image is repeatedly transferred so as to sequentially overlap the intermediate transfer drum 5 that is driven and rotated in synchronization with the image forming apparatus, thereby completing a color toner image on the surface of the intermediate transfer drum 5.

The recording paper 6 is stored and held in a paper cassette 7, one of which is extracted by a paper feed roller 8 and sent to a registration roller 9. The registration roller 9 receives the leading end of the recording paper 6 and makes it stand by. The registration roller 9 feeds out the recording paper 6 in synchronization with the rotation timing of the color toner image formed on the surface of the intermediate transfer drum 5. Press. In the process of forming a color toner image on the intermediate transfer drum 5, the transfer device 10 retracts and waits, advances during transfer, presses the recording paper 6 against the surface of the intermediate transfer drum 5, and generates a transfer bias electric field from the back surface. The transfer gives the color toner image on the surface of the intermediate transfer drum 5 to the recording paper 6.

The recording paper 6 to which the color toner image has been transferred is
The sheet is separated from the intermediate transfer drum 5 at a position past the transfer device 10 and is sent to the fixing device 11.

The fixing device 11 is provided with a fixing guide 12 for receiving the recording paper 6 toward a predetermined portion, a heating roller 13 and a pressure roller 14 which rotate while pressing and forming a nip. Heat roller 13 with paper 6
The toner image is heated and pressurized by being sandwiched and rotated between the roller and the pressure roller 14, melted and fixed on the recording paper 6, and sent out to the paper discharge conveyance path 15. The heating roller 13 has a built-in heater, and the pressure roller 14 has a built-in heater as necessary.

The cooling fan 16 ventilates the inside of the fixing device 11 and its surroundings so as to discharge the heated air outside the apparatus.

The paper discharge conveyance path 15 includes a switching lever 19 at a branch portion for switching the paper conveyance destination to the paper discharge tray 17 or the recording paper reversing mechanism 18 on the upper surface of the machine. Output tray 1
7 is provided with a discharge roller 2 at the end thereof.
0, and the discharge conveyance path 15 to the recording paper reversing mechanism 18
The opening b of the recording paper reversing mechanism 18 is open toward the entrance of the reversing conveyance path 21 of the recording paper reversing mechanism 18.

The paper discharge conveyance path 15 is provided with a first paper passage sensor 22 for detecting the recording paper 6 passing through the paper discharge conveyance path 15 between the fixing device 11 and the switching lever 19. Immediately after the recording tray 6, a discharge tray full sensor 23 for detecting the upper limit of the amount of recording paper 6 stored on the discharge tray 17 is provided. Second paper passage sensor 24 for detecting
Is provided. The first paper passage sensor 22 is installed as close to the fixing device 11 as possible,
Numeral 3 is installed so as to also respond to the recording paper 6 that passes through the paper discharge roller 20 and falls onto the paper discharge tray 17.

The recording paper reversing mechanism 18 further includes a number of transport rollers 25 and a transport guide 26, and sends out the inverted recording paper 6 toward the registration rollers 9.

FIG. 2 is an exploded perspective view showing a specific structure of the main body of the electrophotographic recording apparatus excluding the recording sheet reversing mechanism 18. The main body of the electrophotographic recording apparatus is provided with a developing unit removable cover 111 and a paper discharge cover 112 on a machine frame main body 110, and as shown in FIG.
The developing unit 4C-4K is opened by opening the developing unit detachable cover 111 by opening the developing unit detachable cover 111.
Is removable.

Reference numeral 39 denotes a lubricating oil tank.

FIG. 3 is a block diagram of a control system of the electrophotographic recording apparatus. A control device 201 configured using a microcomputer receives a recording instruction and recording data from the host 300 and executes electrophotographic recording control according to a preset control program.

The control unit 201 receives detection signals from the temperature sensor 203, the first paper passage sensor 22, the paper discharge tray full sensor 23, and the second paper passage sensor 24 via the input / output circuit 202, and Drive mechanism controller 204, charger controller 205, exposure device controller 206, transfer device controller 207, fixing device controller 208, cooling fan controller 2
09 is controlled.

Here, the temperature sensor 203 is connected to the fixing device 1.
1 is a non-contact type sensor for detecting the temperature of the heating roller 13 in FIG.

Various drive mechanism control units 204 drive the photosensitive belt 1 to rotate, advance and retreat the developing units 4C to 4K, drive the developing rollers, rotate / stop the sheet feed roller 8, rotate / stop the registration roller 9, and so on. Heating roller 13 of fixing device 11
In addition, it controls power supply to a motor, an electromagnetic clutch, and an electromagnetic solenoid for rotating the pressure roller 14, switching the switching lever 19, and rotating the discharge roller 20 and the transport roller 25.

The charger control unit 205 controls power supply to the charger 2 that uniformly charges the photosensitive belt 1.

The exposure device control section 206 controls the generation and deflection of an exposure beam (laser beam) from the exposure device 3.

The transfer unit control unit 207 controls the transfer unit 10
And the generation of a transfer electric field are controlled.

Further, the fixing device control section 208 controls power supply to a heater for heating the heating roller 13 in the fixing device 11.

The cooling fan controller 209 controls power supply to the cooling fan 16.

Upon receiving a recording instruction from the host 300, the control device 201 starts preparation control for electrophotographic recording.
In the preparation control, the control device 201 controls the fixing device 1
The heater for heating the first heating roller 13 is heated to heat the heating roller 13 to a predetermined temperature, the photosensitive belt 1 is rotationally driven to remove the residual toner, and the reference position is moved to the exposure position. To stabilize the deflection speed of the laser beam, activate the developing device 4 to stir the developer and uniformly adhere the developer to the surface of the developing roller so that the developing device is ready for development. The control units 204 to 209 are controlled so as to be separated from the transfer roller 5 and put on standby, and to start the cooling fan 16.

When the preparation is completed, the control device 20
1, when the reference position of the photosensitive belt 1 passes through a predetermined portion, the paper feed roller 8 is rotated to send out the recording paper 6 to the registration roller 9 to be on standby, while receiving the recording data from the host 300 and An electrostatic latent image is formed by exposing the surface of the photosensitive belt 1 by controlling the blinking of the laser diode.

When the photosensitive belt 1 is rotated so that the electrostatic latent image faces the developing device 4, one developing unit 4C (4M to 4K) corresponding to the electrostatic latent image is advanced, and the photosensitive belt is exposed to the developer. The drive mechanism control unit 204 is controlled so that the electrostatic latent image is developed by rubbing 1 to form a toner image.

The toner image on the photosensitive belt 1 is transferred to the intermediate transfer drum 5 when the photosensitive belt 1 rotates while contacting the intermediate transfer drum 5. The formation of the electrostatic latent image and the formation of the toner image are repeated for each color, and each toner image is repeatedly transferred so as to overlap on the intermediate transfer drum 5, thereby completing a color toner image on the surface of the intermediate transfer drum 5. .

The driving mechanism is controlled so that the recording paper 6 which has been kept on standby by the registration rollers 9 is fed out so as to synchronize with the transport timing when the completed color toner image on the surface of the intermediate transfer drum 5 reaches the part of the transfer unit 10. The unit 204 is controlled. Then, the transfer device 10 is advanced to press the recording paper 6 against the intermediate transfer drum 5 and to apply a transfer electric field, thereby transferring the color toner image on the intermediate transfer drum 5 to the recording paper 6. The unit 207 is controlled.

Recording paper 6 on which the color toner image has been transferred
Is separated from the intermediate transfer drum 5 after passing the transfer position, guided by the fixing guide 12, and enters the fixing device 11,
When passing between the heating roller 13 and the pressure roller 14, the toner image is fixed by being pressed and heated.

The recording paper 6 fixed by the fixing device 11 is sent out to a paper discharge conveyance path 15. The recording paper 6 sent out to the paper discharge conveyance path 15 is immediately detected by the first paper passage sensor 22, and thereafter, at the branch portion, the paper discharge conveyance path 15 a to the paper discharge tray 17 or the recording paper reversal by the switching lever 19. The process branches off to a paper discharge conveyance path 15b to the mechanism section 18.

The recording paper 6 that has advanced to the paper discharge conveyance path 15a to the paper discharge tray 17 is conveyed by the paper discharge rollers 20 and discharged onto the paper discharge tray 17. At this time, when the recording paper 6 comes out of the paper discharge roller 20, it touches the paper discharge tray full sensor 23 to activate the paper discharge tray full sensor 23, and falls on the paper discharge tray 17, so that the paper discharge tray is full. Sensor 2
3 and returns the paper discharge tray full sensor 23 to its original position. However, when the discharge tray 17 is full of the recording paper 6 discharged and accumulated, the falling amount of the recording paper 6 that has exited the discharge roller 20 decreases. The discharge tray full sensor 23 is kept operated and remains in operation (does not return).

Accordingly, the control device 201 recognizes at an early stage whether or not the recording paper 6 has left the fixing device 11 based on the detection signal from the first paper passage sensor 22, and subsequently, the discharge tray full sensor 23 , It can be recognized that the sheet has been discharged to the sheet discharge tray 17 based on the detection signal from. When the activated paper output tray full sensor 23 does not return, it can be recognized that the paper output tray 17 is full.

The recording paper 6 that has advanced to the paper discharge conveyance path 15b is
The sheet enters the reversing conveyance path 21 of the recording sheet reversing mechanism 18, is conveyed by the conveyance roller 25, and is
4 detects that the sheet is being conveyed through the reverse conveyance path 21.

Accordingly, the control device 201 recognizes at an early stage whether or not the recording paper 6 has left the fixing device 11 based on the detection signal from the first paper passage sensor 22,
Can be recognized based on the detection signal from the paper passage sensor 24 of the recording paper reversing mechanism 18.

Eventually, the control unit 201 makes a logical judgment of the detection signals of the first paper passage sensor 22, the paper discharge tray full sensor 23, and the second paper passage sensor 24, so that the recording paper 6 is fixed. It is determined whether or not the recording paper 6 has been discharged to the paper discharge tray 17 or the recording paper reversing mechanism 18 after passing through the apparatus 11, and the limit of the accumulation amount of the recording paper 6 discharged to the paper discharge tray 17 is monitored. be able to.

FIG. 4 is an enlarged longitudinal side view showing a fixing device and a paper discharge conveyance path in the electrophotographic recording apparatus.

The fixing guide 12 in the fixing device 11 is
On its surface, a plurality of beads 12a extending in the transport direction of the recording paper 6 are provided, and a rear edge 12a facing the heating roller 13 is provided.
b is formed flat. The rear edge 12 of the fixing guide 12
b approaches the heating roller 13 and the fixing device 11
Is guided so that the leading end of the recording paper 6 entering the roller 11 slides on the bead 12a and hits the heating roller 13. Then, the leading end of the recording paper 6 abuts on the heating roller 13, and advances along with the heating roller 13 along the heating roller 13 to move the heating roller 13 and the pressure roller 14.
When the recording paper 6 is pulled by being sandwiched between the pressure contact portions, the recording paper 6 is tensioned because the rear area of the recording paper 6 is sandwiched between the intermediate transfer drum 5 and the transfer device 10 and adheres to the intermediate transfer drum 5. . When the recording paper 6 is tensioned between the portion where the recording paper 6 is attached to the intermediate transfer drum 5 and the holding portion between the heating roller 13 and the pressure roller 14, the rear edge 12 b of the fixing guide 12 is moved to the heating roller 13.
Since the recording paper 6 is positioned so as to be close to the side, the back surface of the recording paper 6 is brought into strong contact with the rear end edge 12b of the fixing guide 12, and the recording paper 6 is bent so that the surface thereof becomes mountain-shaped.

At this time, if the bead 12a on the surface of the fixing guide 12 makes strong contact with the back surface of the bent recording paper 6,
The heat of the bead 12b, which has become hot, is transmitted to the recording paper 6 to cause uneven fixing.

Accordingly, in this embodiment, the recording paper 6 is attached to the intermediate transfer drum 5 and the heating roller 13
The fixing guide 1 is tensioned between the
The rear surface of the recording paper 6 is configured not to strongly contact the bead 12a of the fixing guide 12 even when the rear edge 12b is bent at the rear edge 12b. Such a configuration shortens the trailing edge of the bead 12a (increases the distance from the trailing edge 12b of the fixing guide 12) and / or reduces the bead 12a.
It can be realized by reducing the height (height) of a.

Such a fixing guide can also be applied to an electrophotographic recording apparatus in which a toner image formed on a photosensitive drum using a photosensitive drum is transferred to recording paper by a transfer device and sent to a fixing device.

A cleaning roller 27 for cleaning the surface of the heating roller 13 is rotatably attached to a cleaning case 28 to form a unit. The cleaning roller 27 is juxtaposed so as to contact the heating roller 13 and is detachably mounted from above. . Then, in the mounted state, the cleaning roller 27 is rotationally driven so as to slightly slip at a different peripheral speed with respect to the heating roller 13. The cleaning case 28 has a grip rib 28a projecting upward as a handle for attaching and detaching operation, and the grip rib 28a is provided with a ventilation hole 28b. The ventilation holes 28b reduce heat transfer to the upper edge portion gripped during attachment / detachment to reduce a rise in the temperature of the portion, and also facilitate the flow of warm air drawn by the cooling fan 16 through the temperature sensor 203. To

A non-contact type temperature sensor 203 for detecting the temperature of the heating roller 13 is provided on the cleaning roller 27 side so as to face the heating roller 13. The air heated by the heating roller 13 is drawn by the cooling fan 16, passes through the temperature sensor 203, and flows so as to bypass the cleaning case 28.
Since the region of the grip rib 28a protruding upward can pass through the ventilation hole 28b formed in the grip rib 28a, a relatively smooth flow can be formed.

A cleaning pad 29 for cleaning the surface of the pressure roller 14 is backed by a back plate 30 and attached by a leaf spring 31 so as to be in pressure contact with the surface of the pressure roller 14. As described above, if the lubrication of the surface of the pressure roller 14 is insufficient, the cleaning pad 29 slides intermittently and vibrates, causing noise.

The present inventors have determined that this vibration noise is caused by the vibration of the cleaning pad 29 caused by the resonance of the surrounding components, particularly the back plate 30 and the leaf spring 31, and in this embodiment, The configuration is such that a weight (not shown) is welded and attached to the back plate 30 to shift the resonance frequency with respect to the vibration of the cleaning pad to thereby prevent the generation of noise.

In order to prevent the fixing device 11 from overheating, a temperature fuse 32 is provided below the pressure roller 15.
Are connected in series to a power supply circuit to a heater for heating the heater.
As described above, the thermal fuse 32 is mounted on the support 33 made of synthetic resin.
When an insert screw is used, the connection of the insert screw is loosened and the fixing becomes unstable. Therefore, in this embodiment, as shown in FIGS.
A groove 33a into which the connection terminal plate 34 is inserted from the lateral direction;
A relief hole 33b for accommodating the protruding tip of a set screw 35 for fixing the terminal 32a of the thermal fuse 32 is formed in the connection terminal plate 34, and the connection terminal plate 34 inserted into the groove 33a is formed.
When the set screw 35 is screwed into the screw hole 34a and the terminal 32a is fixed, the distal end of the set screw 35 that penetrates through the screw hole 34a and protrudes downward is fitted into the relief hole 33b, thereby making connection. The terminal plate 34 was attached to the support 33 so as not to come off.

The heating roller 13 of the fixing device 11
As described above, if the pressing roller 14 is stopped for a long time in a state where the pressing roller 14 is pressed, the surface of the pressing roller 14 is permanently deformed. Further, the pressure contact of the pressure roller 14 is also released during maintenance work for removing the wound recording paper 6. In this embodiment, a pressure releasing lever 36 that tilts forward and backward is provided as shown in FIGS. 6 and 7 to release the pressure contact of the roller.

The fixing device 11 includes a heating roller 13 and a bearing 3.
The pressure roller 14 is supported so as to rotate in a stationary state by the pressure roller 7, and the pressure roller 14 is movably supported by a bearing 38, and is pressed against the heating roller 13 by a pressure contact spring (not shown). The pressure release lever 36 is attached so as to be tiltable concentrically with the bearing 37, and abuts a cam 36 a formed on the rotating peripheral edge with a bearing 38 that supports the pressure roller 14. When the pressure release lever 36 is tilted forward and backward, the cam 36a pushes the bearing 38 back against the pressing force of the pressing spring in each tilted state, pulls the pressing roller 14 away from the heating roller 13 and presses the pressing. When the pressure release lever 36 is returned to the neutral state, the bearing 38 is released so that the pressure roller 14 is pressed against the heating roller 14 by a spring.

The pressure release lever 36 is provided with a tilting operation portion 36b projecting upward for tilting operation. The forward and backward tilting of the pressure release lever 36 is performed by manually operating the tilting operation unit 36b.

At the time of the maintenance work, as shown in FIG. 7, the discharge cover 112 is opened to expose the fixing device 11, and the tilting operation section 36b is operated to tilt the pressure release lever 36 rearward so that the pressure roller 14 is rotated. Of the heating roller 13
Alternatively, the recording paper 6 wound around the pressure roller 14 can be easily removed. When the maintenance work is completed, the tilt release section 36b is operated to return the pressure release lever 36 to the neutral state, and then the discharge cover 112 is closed. Pressure release lever 36
When the paper output cover 112 is closed with the camera kept tilted backward, the contact portion 112a of the paper output cover 112 comes into contact with the tilt operation portion 36b, and the pressure release lever 36 is pushed back to the neutral state, and the pressure roller is pressed. 14 is pressed against the heating roller 13.

At the time of shipping, as shown in FIG. 6, the pressure release lever 36 is tilted forward to release the pressure contact. This is to prevent the pressure release lever 36 from being pushed back when the discharge cover 112 is closed when the pressure release lever 36 is tilted backward. The electrophotographic recording apparatus, when in use, uses the heating roller 1 of the fixing device 11.
Since the units of the cleaning roller 27 are mounted side by side above 3, the pressure release lever 36 is prevented from tilting backward. However, since the unit of the cleaning roller 27 is a replacement (consumable) part, it is packed in an unmounted state at the time of shipment. Therefore, at the time of shipping, the paper discharge cover 112 can be closed with the pressure release lever 36 tilted forward to release the pressure contact of the pressure roller 14. And at the time of use,
Return to the neutral squad indicated by the dashed line and return to the cleaning roller 27.
Install the unit.

The fixing device 11 configured as described above is similar to that shown in FIG.
As shown in FIG. 9 and FIG. 9, the set screw 42 is opened from the top by opening the paper discharge cover 112 of the machine frame main body 110 and placed on the fixing device mounting portion 113 along the side surfaces of the end covers 40 and 41 on both sides. , 43 are fixed to the fixing device mounting portion 113 by screwing. The set screws 42, 43 are formed to have a length exceeding the height of the end covers 40, 41, and the set screws 42, 43 are formed in concave portions 40a, 41a formed on the outer surfaces of the end covers 40, 41 so as to extend in the vertical direction.
Is disposed so that the head thereof is housed so as to protrude upward, thereby facilitating the attaching / detaching operation.

The recess 40a is formed at a corner of the end cover 40, and one side wall is omitted. In any case, on the side walls of the recesses 40a, 41a, the claws 40 facing each other with a space slightly smaller than the diameter of the body of the setscrew 42, 43.
By providing the set screws 42 and 43 by pushing the set screws 42 and 43 inside the claws 40 b and 41 b, when the fixing device 11 is removed, the set screws 4 and 43 are provided.
2, 43 can be prevented from being scattered.

As shown in FIG. 10, the paper discharge roller 20
The driving roller 46 is rotatably supported by a plurality of driving rollers 46 fitted on a roller driving shaft 45 and a spring member 47.
And a plurality of pressure rollers 48 respectively pressed against each other.
The pressure roller 48 has tapered end portions to form the small-diameter portion 4.
A rubber cylinder 48d is fitted around the outer periphery of the large-diameter portion of the substantially cylindrical core member 48c formed with 8a, 48b, and both ends of the rubber tube 48d are positioned around the small-diameter portions 48a, 48b and run inward. A space is formed, and there are burrs at both ends of the rubber cylinder 48d.
Is heated by bending the end of
Even if the HP sheet passes, a strong pressing force that damages the sheet is prevented from being generated.

In this embodiment, the driving roller 4
6 is made of chloroprene rubber with an outer diameter of 16 mm and a length of 2
The pressure roller 48 has a core member 48c having a large diameter portion having a diameter of 8 mm, 3 mm.
The minimum diameter of the small-diameter portions 48a and 48b is formed to 7 mm by resin molding using a taper having a length of 7 mm, and a rubber cylinder 48d is formed.
Is made of chloroprene rubber with an outer diameter of 10 mm and a hardness of Hs
= 70 ° cylindrical member.

[0074]

The present invention has a fixing device for fixing a recording sheet on which a toner image has been transferred by passing the recording sheet between a heating roller and a pressure roller which rotate in a pressure-contact state, and can be opened and closed by rotating backward. An electrophotographic recording apparatus having a pressure release lever for operating the pressure roller against the heating roller and releasing the pressure, wherein the pressure release lever is in a forward tilted state and a rearward tilted state. The cam and the tilting operation unit release the pressure contact of the pressure roller and bring it into the pressure contact state in the neutral state, so that the pressure contact between the heating roller and the pressure roller of the fixing device can be released and pressed during transportation and maintenance work. Can be realized with a small number of components.

Further, the present invention comprises a fixing device for fixing the recording paper on which the toner image has been transferred, by passing the recording paper between a heating roller and a pressing roller rotating in a pressure-contact state, and fixing the fixing device to a frame. In the electrophotographic recording apparatus mounted on the apparatus mounting portion from above and fixed with set screws, the set screw is arranged along the side surfaces of both end covers and screwed to the fixing device mounting portion. By doing so, the work of attaching and detaching the fixing device can be facilitated.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a basic configuration of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a specific configuration of a main body portion of a two-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention, excluding a recording sheet reversing mechanism.

FIG. 3 is a block diagram of a control system of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention.

FIG. 4 is a longitudinal sectional side view showing, in an enlarged manner, a fixing device and a sheet discharge conveyance path in a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention.

FIG. 5 is a longitudinal sectional side view of a thermal fuse in a fixing device of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention, and an exploded perspective view of a main part thereof.

FIG. 6 shows a fixing device of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention at the time of shipping.

FIG. 7 is a side view showing a state of a pressure release lever at the time of maintenance work in the fixing device of the double-sided recording type electrophotographic recording apparatus according to the embodiment of the present invention.

FIG. 8 is a side view showing an installation state of a fixing device of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention.

FIG. 9 is a plan view of a principal part showing an installation state of a fixing device of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention.

FIG. 10 is a front view showing a part of a discharge roller of a double-sided recording type electrophotographic recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive belt, 3 ... Exposure device, 4 ... Developing device, 5 ... Intermediate transfer drum, 10 ... Transfer device, 11 ... Fixing device, 12 ...
Fixing guide, 12a bead, 12b rear edge, 13
Heating roller, 14 ... Pressing roller, 15, 15a, 15b
... paper discharge transport path, 16 ... cooling fan, 17 ... paper discharge tray,
18 recording sheet reversing mechanism, 19 switching lever, 20
Discharge rollers, 21: reverse conveyance path, 22: first paper passage sensor, 23: discharge tray full sensor, 24: second paper passage sensor, 27: cleaning roller, 28: cleaning case, 28a: gripping rib , 28b ... vent hole, 29
... cleaning pad, 30 ... back plate, 31 ... leaf spring, 3
2: thermal fuse, 33: support, 33a: groove, 33b
... escape hole, 34 ... connection terminal board, 35 ... set screw, 36 ...
Pressure release lever, 36a: cam, 36b: tilt operation unit,
40, 41 ... end cover, 40a, 41a ... recess, 4
2, 43: set screw, 46: drive roller, 47: spring member, 48: pressure roller, 48a, 48b: small diameter portion, 48
c: core member, 48d: rubber cylinder, 110: machine frame body, 11
Reference numeral 2 denotes a discharge cover, 113 denotes a fixing device mounting portion, 201 denotes a control device, and 203 denotes a temperature sensor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Riki Hiraoka 1-1-1 Higashitaga-cho, Hitachi City, Ibaraki Prefecture Inside the Office Information Equipment Division, Hitachi, Ltd. (72) Inventor Katsuyoshi Onose Higashi Taga-machi, Hitachi City, Ibaraki Prefecture 1-1-1 1-1 F-term (reference) in Hitachi, Ltd. Office Information Equipment Division 2H033 AA02 AA23 AA36 BA49 BB01 BB28 BB35

Claims (6)

[Claims] A fixing device for fixing a recording sheet on which a toner image has been transferred by passing the recording sheet between a heating roller and a pressure roller rotating in a pressure-contact state; The fixing device is an electrophotographic recording apparatus including a pressure release lever that operates to press and release the pressure roller against the heating roller, wherein the pressure release lever presses in a forwardly inclined state and a rearwardly inclined state, respectively. An electrophotographic recording apparatus, comprising: a cam for releasing pressure contact of a roller and bringing the roller into a pressure contact state in a neutral state; and a tilt operation unit. 2. The pressure release lever according to claim 1, wherein the pressure release lever is pivotable rearward to be tiltable rearward in an open state and is closed when the discharge cover is closed in a state tilted rearward. An electrophotographic recording apparatus characterized in that the sheet is returned to a neutral state by being pushed by a discharge cover. 3. The fixing device according to claim 1, wherein the fixing device includes a detachable cleaning roller that contacts a heating roller, and the pressure release lever can be tilted forward with the cleaning roller removed. Electrophotographic recording device. 4. An electrophotographic recording apparatus according to claim 1, wherein said pressure release lever is tilted forward during shipping. 5. A fixing device for fixing a recording sheet on which a toner image has been transferred by passing the recording sheet between a heating roller and a pressure roller rotating in a pressure-contact state, and fixing the fixing device to a fixing device mounting portion of a frame. Wherein the set screw is arranged along the side surfaces of the end covers on both sides and screwed to the fixing device mounting portion. An electrophotographic recording device. 6. The end screw according to claim 5, wherein the set screw has a length exceeding the height of the end cover, and is disposed in a recess formed on the outer surface of the end cover so as to extend in the vertical direction. An electrophotographic recording apparatus characterized in that is accommodated so as to protrude upward.