JPH11143335A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which is improved in maintainability and excellent in reliability. SOLUTION: At the time of removing a carrying belt unit 12, a fixing unit 8 is pulled out from the rear part of a device, a machine screw is loosened from the rear part of the device to slide the carrying belt unit 12 in a direction perpendicular to the carrying direction of a transfer material, and the carrying belt unit 12 and a carrying belt base stay are positioned to remove a drive transmission coupling and pull out the carrying belt unit 12 to the rear of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine or the like using an electrophotographic system, and more particularly to a method of transferring a toner image to a transfer material and then fixing the transfer material. The present invention relates to an image forming apparatus provided with a transport unit that transports a sheet to a unit.

[0002]

2. Description of the Related Art Conventionally, as this type of image forming apparatus, for example, there are a copying machine, a printer, a facsimile machine and the like.

A copying machine generally has a function of reading an image of an original or the like and forms an image on a sheet based on the read image information. Some copiers have a function of inputting image information to be sent.

[0004] A printer is generally an external device,
For example, an image is formed on a sheet based on image information sent from an apparatus such as a computer, and a facsimile apparatus generally has a function of reading an image of a document,
Further, it has a communication function, sends read image information to the outside, and forms an image on a sheet based on information sent from the outside.

In these image forming apparatuses, a transfer material is provided on a transfer material.
After a development (toner image) formed on an image carrier such as a photoconductor drum is transferred, there is a device having a transfer device for transferring a transfer material to a fixing device for fixing a transferred unfixed image. .

Hereinafter, an image forming apparatus according to the related art provided with such a transport device will be described with reference to FIG. 9 and FIG.

FIG. 9 is a schematic sectional view of a monochrome laser printer according to the prior art, and FIG. 10 is a schematic sectional view of a monochrome copier according to the prior art.

First, a case of a black-and-white laser printer will be described as an example of an image forming apparatus with reference to FIG.

In FIG. 9, a transfer material (cut paper or the like) S sent from a cassette tray 107a by a half-moon-shaped pickup roller 107e is fed by a feed roller 107.
One sheet is separated by f and a pair of retard rollers 107g, conveyed to a conveying roller pair 107b, and reaches a registration roller pair 107d.

Thereafter, a pair of registration rollers 107d is rotated in accordance with rotation of a photosensitive drum 101 as an electrophotographic photosensitive member disposed in a process cartridge B serving as recording means.
Then, the transfer material S is conveyed, and the transfer roller 105 transfers the toner image on the photosensitive drum 101 onto the transfer material S.

The transfer material S conveyed by the nip portion between the photosensitive drum 101 and the transfer roller 105 is conveyed along a conveyance belt 112a, a flat conveyance guide rib 112b, and a fixing entrance guide 108c directed downward of the conveyance belt unit 112. Go.

Thereafter, the transfer material S is heated and pressed by the nip portion between the heating roller 108b and the pressure roller 108a, and the toner image on the transfer material S is fixed as a permanent image.
The sheet is conveyed along a conveyance guide rib 115 via a sheet discharge roller pair 113, and is discharged and stacked on a face down tray 110 at an upper portion of the apparatus main body by the sheet discharge roller pair 109.

Next, a case of a black-and-white copying machine as an example of the image forming apparatus will be described with reference to FIG.

The same components as those of the laser printer shown in FIG. 9 will be described with the same reference numerals.

As shown in FIG. 10, similarly to the laser printer, the transfer material S sent out from the cassette tray 107a by the pickup roller 107e is separated by a pair of a feed roller 107f and a retard roller 107g into one sheet. Transported to the pair 107b,
It reaches the registration roller pair 107d.

Thereafter, a registration roller pair 107d is rotated in accordance with rotation of a photosensitive drum 101 as an electrophotographic photosensitive member disposed in a process cartridge B serving as recording means.
, The toner image on the photosensitive drum 101 is transferred onto the transfer material S by the transfer device 105, and is conveyed by the flat conveyance belt 112a to be nipped by the nip portion of the fixing roller pair, and the face-up is performed. The sheets are discharged and stacked on the tray 117.

[0017]

However, in the case of the above-described prior art, the following problems have occurred.

Conventionally, the above-mentioned transport belt unit 112 is a mold integrally formed with the apparatus main body in a small apparatus, or is mounted on a frame of the apparatus main body in an apparatus of a medium or larger size from above or from the side. Since it was fixed with screws, it could not be easily removed to the outside of the device body.

Therefore, due to long-term use of the apparatus, the transport belt in the transport belt unit 112 is damaged, toner is scattered, the transport belt is stained by paper dust, or the like, and the drive transmission between the transport belt and the belt drive shaft is caused by these. There is a problem that it is very difficult to replace and clean the conveyor belt when the slippage occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide an image forming apparatus having improved reliability and improved maintenance.

[0021]

According to the present invention, in order to achieve the above object, a transfer means for transferring a toner image formed on an image carrier to a transfer material, and a toner image formed by the transfer means are provided. An image forming apparatus comprising: a transport unit that transports a transferred transfer material; and a fixing unit that fixes a toner image on the transfer material transported by the transport unit. The transport unit is freely detachable from the apparatus main body by removing the fixing unit from the apparatus.

Therefore, since the transport unit is detachable from the apparatus main body, the transport unit can be easily cleaned and replaced.

The transport unit includes a transport belt for transporting the transfer material, and a drive shaft for driving the transport belt, wherein the drive shaft is moved in a thrust direction with respect to a drive transmission unit provided on the apparatus main body side. Also, it is preferable that the connection and disconnection can be freely performed with a predetermined play in the radial direction.

According to this structure, since the backlash is provided, the displacement of the drive shaft with respect to the drive transmission means is absorbed.

It is preferable that the drive shaft and the drive transmitting means are configured to be freely connected and disconnected by a coupling structure.

When the transport unit is positioned by the positioning means for positioning the transport unit in the apparatus main body, the drive shaft may be simultaneously positioned at a position where the drive shaft is connected to the drive transmitting means.

By sliding the transfer unit in a direction perpendicular to the transfer material transfer direction, the connection between the drive shaft and the drive transmission means is released, and the transfer unit can be removed in the direction in which the fixing means has been removed. It should be possible.

It is preferable that the transport unit can be removed by passing through a space formed after removing the fixing unit.

[0029]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

An image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS.

In this embodiment, a four-color full-color laser beam printer will be described as an example of an image forming apparatus.

First, the overall configuration of the image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention.

As shown in the figure, the image forming apparatus A includes a drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) 1 as a first image carrier.

The photosensitive drum 1 is driven to rotate counterclockwise in FIG. 1 by a driving means (not shown).

A charging device 2 for uniformly charging the surface of the photosensitive drum 1 in order according to the direction of rotation of the photosensitive drum 1 irradiates a laser beam based on image information to irradiate the photosensitive drum 1 with an electrostatic charge. Exposure means 3 for forming a latent image, developing device 4 for attaching toner to the electrostatic latent image to develop it as a toner image, and second transfer means for transferring the toner image on photosensitive drum 1 to primary transfer An intermediate transfer unit 5 serving as an image carrier, a cleaning device 6 for removing post-transfer toner remaining on the surface of the photosensitive drum 1 after the primary transfer, and the like are provided.

Here, the photosensitive drum 1, the charging device 2, and the cleaning device 6 for removing toner are integrated into a cartridge to form a process cartridge B, which can be attached to and detached from the apparatus main body 14 of the image forming apparatus A. ing.

In addition, a recording medium (transfer material) S is fed toward the intermediate transfer unit 5 and a feeding means 7 for feeding the transfer material S, a toner image is formed on the transfer material S after the secondary transfer. A fixing device 8 as fixing means for fixing is provided.

Hereinafter, the photosensitive drum 1 will be described in detail.

The photosensitive drum 1 is formed, for example, on an outer peripheral surface of an aluminum cylinder having a diameter of 47 mm by an organic photoconductive layer (O
(PC photoreceptor).

The photosensitive drum 1 is rotatably supported at both ends by supporting members, and is rotated in the direction of the arrow by a driving force from a driving motor (not shown) being transmitted to one end. Driven.

The charging device 2 is described in, for example,
A so-called contact charging type as shown in JP-A-149669 can be used.

The charging member is a conductive roller formed in a roller shape. The roller is brought into contact with the surface of the photosensitive drum 1 and a charging bias voltage is applied to the roller by a power supply (not shown). And to uniformly charge the surface of the photosensitive drum 1.

The exposure means 3 has a polygon mirror 3a, and the polygon mirror 3a is irradiated with image light corresponding to an image signal by a laser diode (not shown).

The polygon mirror 3a is rotated at a high speed by a scanner motor (not shown), and selectively exposes the surface of the charged photosensitive drum 1 to the reflected image light via the imaging lens 3b and the reflection mirror 3c. To form an electrostatic latent image.

The developing device 4 accommodates a rotating body 4A rotatable around an axis 4d and four developing units mounted thereon, that is, toners of yellow, magenta, cyan, and black, respectively. Developing units 4Y, 4M, 4C, 4Bk
It has.

When the electrostatic latent image on the photosensitive drum 1 is developed, a predetermined developing device of a color to be attached to the electrostatic latent image is arranged at a developing position.

That is, a predetermined developing unit is stopped at a developing position facing the photosensitive drum 1 by the indexing rotation of the rotating body 4A, and the developing sleeve 4b of the developing unit is further provided with a minute gap (300 μm) with respect to the photosensitive drum 1. Then, the electrostatic latent image on the photosensitive drum 1 is developed.

This development is performed as follows.

First, the toner in the container of the developing device corresponding to the color to be developed is sent to the coating roller 4A by the feeding mechanism, and the rotating coating roller 4a and the toner regulating blade 4
By (c), a thin layer of toner is applied to the outer periphery of the rotating developing sleeve 4b, and charge is applied to the toner (frictional charging).

Then, by applying a developing bias between the developing sleeve 4b and the photosensitive drum 1 on which the electrostatic latent image is formed, toner is attached to the electrostatic latent image and developed as a toner image. Things.

The sleeve 4b of each of the developing devices 4Y, 4M, 4C, 4Bk is connected to a high-voltage power supply for each color development provided in the image forming apparatus main body 14 when each developing device is located at the developing position. The voltage is selectively applied for each color development.

The developing units 4Y, 4M, 4C, 4Bk
Are configured to be individually detachable from the rotating body 4A.

The intermediate transfer unit 5 serving as the second image carrier transfers a plurality of toner images, which have been primary-transferred sequentially from the photosensitive drum 1 and are superimposed, on the transfer material S collectively. Things.

The intermediate transfer body unit 5 has an intermediate transfer belt 5a running in the direction of arrow R5.

The intermediate transfer belt 5a of the present embodiment is a belt having a circumference of about 440 mm, and is stretched around three rollers of a driving roller 5b, a secondary transfer facing roller 5c, and a driven roller 5d.

Further, there is provided a pressing roller 5j which retreats so as to take a position where the intermediate transfer belt 5a is pressed against the photosensitive drum 1 close to the driven roller 5d and a position where the intermediate transfer belt 5a is separated from the photosensitive drum 1. I have.

The intermediate transfer belt 5a runs in the direction of arrow R5 by the rotation of the driving roller 5b.

Further, at a predetermined position outside the intermediate transfer belt 5a, there is provided a cleaning unit 5e which can be brought into contact with and separated from the surface of the intermediate transfer belt 5a. The remaining transfer material toner is removed.

The cleaning unit 5e brings the charging roller 5f into contact with the intermediate transfer belt 5a to give the toner a charge opposite to that at the time of transfer.

The toner to which the opposite charge is applied is electrostatically attached to the photosensitive drum 1 and then collected by a cleaning device 6 for the photosensitive drum 1 which will be described later.

The method of cleaning the intermediate transfer belt 5a is not limited to the above-described electrostatic cleaning, but may be a mechanical method such as a blade or a fur brush, or a method using both of them.

After the toner developed on the photosensitive drum 1 by the developing device 4 is primarily transferred to the intermediate transfer belt 5a, the cleaning device 6 is a so-called transfer remaining on the surface of the photosensitive drum 1 without being primary-transferred. This is to remove the residual toner.

In the cleaning device 6 shown in FIG. 6, the transfer residual toner is accumulated in the cleaning container 11a.

The feeding / conveying means 7 feeds the transfer material S to the image forming section, and stores a plurality of transfer materials S.

During image formation, the pickup roller 7e
(Half-moon roller), a feed roller 7f, and a retard roller 7g are driven and rotated in accordance with the image forming operation to separate and feed the transfer material S in the sheet cassette 7a one by one, and a guide plate by a transport roller pair 7b. 7c.

The leading end of the transfer material S abuts against the pair of registration rollers 7d and temporarily stops. After forming a loop, the rotation of the intermediate transfer belt 5a is synchronized with the image writing position, and the registration roller pair 7d transfers the image to the intermediate transfer body unit 5. It is re-fed.

The fixing device 8 fixes a plurality of toner images secondary-transferred onto the transfer material S. As shown in FIG. 1, the heating roller 8b which is driven and rotated, and the transfer material S And a pressure roller 8a for applying heat and pressure to the pressure roller 8a.

That is, the transfer material S that has passed through the secondary transfer roller 11 for collectively transferring the toner on the intermediate transfer belt 5 a is transported on the transport belt unit 12, and is transported by the fixing roller pair when passing through the fixing device 8. At the same time, heat and pressure are applied by the heating roller 8b.

Thus, the toner images of a plurality of colors are fixed on the surface of the transfer material S.

Next, the configuration of the transport belt unit, which is a feature of the present embodiment, will be described.

FIG. 3 is a schematic configuration diagram around a transport unit provided in the image forming apparatus according to the embodiment of the present invention.

As shown in FIG. 3, the transfer material S is a secondary transfer opposing roller 5C of the intermediate transfer unit 5 and a secondary transfer roller 5C.
n is discharged downward from the nip portion from the horizontal direction, so that the transport belt unit 1 is a transport unit.
The guide No. 2 is set in a direction of descending to a predetermined position along that direction, and thereafter, is set so as to guide the transfer material S upward toward the nip portion 8d of the fixing roller pair. It has a wide-angle V-shape.

At the valley of the V-shaped conveyance path, a drive shaft 20 for the conveyance belt is provided, and at the peak on the side of the secondary transfer roller 5n, the first driven shaft 21 of the first conveyance belt and the fixing device 8 The second driven shaft 22 of the second conveyor belt is provided at the peak on the side, and is rotatably attached to the conveyor belt table 12c.

FIGS. 4 and 5 are plan views of a transport unit provided in the image forming apparatus according to the embodiment of the present invention.

In FIG. 4, the central portion 20a of the drive shaft 20
Between the first driven shaft 21 and the central portion of the first driven shaft 21.
a (endless belt) is hung.

Further, both ends 20b of the drive shaft and the second driven shaft 2
The second conveyor belt 12b is hung between the two.

When a rotational driving force is applied to the drive shaft 20 in the direction of the arrow Y via the coupling 20c provided at one end of the drive shaft 20, the first transport belt 12a and the second transport belt 12b are transferred. S rotates in a direction to transport S to the fixing device 8 side.

As shown in FIG. 3 to FIG.
2c are provided with insertion ribs 30, 31, 32 and a boss 33, and are provided with positioning belts 35, 36, 37 provided in the cut-and-raised portion of the conveyor belt table stay 34, and the conveyor belt table 12c.
Are inserted until the end faces 30a and 32a of the insertion ribs abut on the cut-and-raised portions of the conveyor belt stay.

The boss 33 is fitted in a positioning groove 40 provided behind the conveyor belt table stay, and
2c is fixed to the conveyor belt stay 34 by a screw 38.

The insertion ribs 30, 31, 32,
Boss 33, positioning holes 35, 36, 37, positioning groove 4
Positioning means is constituted by 0 or the like.

At this time, the drive transmission means 20c provided at the end of the drive shaft 20 of the transport belt is in a state of being engaged with the drive transmission means provided on the apparatus main body side (FIGS. 4 and 6). .

FIG. 8 is an enlarged view of the drive transmitting means (coupling) portion of FIG.

Coupling 2 of drive shaft 20 of conveyor belt
0c has a cross-shaped rib structure, and a tip 39a of the drive gear 39 on the apparatus main body side is provided with a cross-shaped groove.

Then, when these are connected, as shown in FIG. 8, the coupling portion between the conveyor belt drive shaft 20 and the main body drive gear is provided with a play a and b in the thrust direction and the radial direction. The configuration is such that the positional deviation can be absorbed, and the positioning between the couplings is determined at the same time by the positioning of the conveyor belt table 12c.

When removing the conveyor belt unit 12,
As shown in FIG. 2, the fixing device 8 is pulled out from the rear of the apparatus,
Loosen the screw 38 from the rear of the apparatus, slide the conveyor belt unit 12 in the direction of the arrow shown in FIGS. 5 and 7, and position the conveyor belt unit 12 and the conveyor belt table stay.
By removing the drive transmission coupling and passing through the space created after the fixing unit 8 is removed, it is configured to be pulled out to the rear of the apparatus.

It should be noted that mounting can be easily performed in the reverse order.

As described above, if the fixing device 8 is removed from the apparatus main body, the transport belt unit 12 can be easily removed and can be easily attached, so that the transport belt unit 12 can be easily cleaned or replaced. Can be performed, and maintainability is improved.

[0088]

According to the present invention, since the transport unit is detachable from the apparatus main body, the transport unit can be easily cleaned, replaced, etc., so that the maintainability and reliability are improved.

If the drive shaft constituting the transport unit is configured to be freely connected and disconnected with a predetermined play in the thrust direction and the radial direction with respect to the drive transmission means provided on the apparatus main body side, Can be absorbed from the drive transmission means.

The drive shaft and the drive transmitting means can be freely connected and disconnected by a coupling structure.

When the transport unit is positioned in the apparatus main body by the positioning means and the drive shaft is positioned at a position where the drive shaft is connected to the drive transmission means, the unit can be easily attached and detached.

By sliding the transport unit in the direction perpendicular to the transport direction of the transfer material, the connection between the drive shaft and the drive transmitting means is released, and the transport unit can be removed in the direction from which the fixing means has been removed. .

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a state in which a fixing device of the image forming apparatus according to the embodiment of the present invention is removed.

FIG. 3 is a schematic configuration diagram around a transport unit provided in the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a plan view of a transport unit provided in the image forming apparatus according to the embodiment of the present invention.

FIG. 5 is a plan view of a transport unit provided in the image forming apparatus according to the embodiment of the present invention.

FIG. 6 is a rear view of a transport unit provided in the image forming apparatus according to the embodiment of the present invention.

FIG. 7 is a rear view of a transport unit provided in the image forming apparatus according to the embodiment of the present invention.

FIG. 8 is an enlarged view of a drive transmission means (coupling) portion in FIG. 4;

FIG. 9 is a schematic cross-sectional view of a black-and-white laser printer according to the related art.

FIG. 10 is a schematic sectional view of a black-and-white copying machine according to the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 5 Intermediate transfer body unit 8 Fixing device 12 Conveying belt unit 12a First conveying belt 12b Second conveying belt 20 Drive shaft 21 First driven shaft 22 Second driven shaft 30, 31, 32 Insertion rib 33 Boss 20c Coupling 38 Screw 39 Drive gear 39a Tip (of drive gear) 40 Positioning groove

Claims (6)

[Claims] A transfer unit configured to transfer a toner image formed on an image carrier onto a transfer material; a transfer unit configured to transfer a transfer material onto which the toner image has been transferred by the transfer unit; A fixing unit for fixing the toner image on the transfer material, wherein the fixing unit is provided detachably with respect to the apparatus main body, and the fixing unit is detached from the apparatus, whereby the transport unit is removed. An image forming apparatus characterized in that the image forming apparatus is also detachable from the apparatus main body. 2. The image forming apparatus according to claim 1, wherein the transport unit includes a transport belt that transports the transfer material, and a drive shaft that drives the transport belt. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to be freely connected and disconnected with a predetermined amount of play in a thrust direction and a radial direction. 3. The image forming apparatus according to claim 2, wherein the drive shaft and the drive transmission means are configured to be freely connected and disconnected by a coupling structure. 4. When the transport unit is positioned by a positioning means for positioning the transport unit in the apparatus main body, the drive shaft is simultaneously positioned at a position where the drive shaft is coupled to the drive transmitting means. Item 4. The image forming apparatus according to item 2 or 3. 5. A connection between the drive shaft and the drive transmission means is released by sliding the transfer unit in a direction perpendicular to a transfer material transfer direction, and the transfer unit is removed in a direction in which the fixing means is removed. The image forming apparatus according to claim 2, wherein the image forming apparatus is capable of performing the following. 6. The image forming apparatus according to claim 1, wherein the transport unit can be removed by passing through a space formed after removing the fixing unit.