JP2002072618A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device being free from breakage of transfer material S by an electrostatic attracting roller 22, damage to component adjacent thereto or the like, when an electrostatic transfer belt 11 is retreated from a transferring part at the time of eliminating a jamming in a transferring part, or replacing a processing cartridge 7. SOLUTION: This image forming device is provided with plural photoreceptor drums 1 respectively arranged in the vertical direction, an electrostatic transfer belt 11 being held in contact with the photoreceptor drum 1 for transporting the transfer material S and the statically attracting roller 22 being held in contact with the static transfer belt 11 for statically attracting the transfer material S to the static transfer belt 11. The static transfer belt 11 is disposed attachably/detachably to/from the image forming device main body, and the static attracting roller 22 is disposed on the image forming device main body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine or a color printer employing an electrophotographic system.

[0002]

2. Description of the Related Art Conventionally, there is an image forming apparatus in which a plurality of photosensitive drums are arranged in a line. Such image forming apparatuses are roughly classified into a horizontal arrangement in which a plurality of photosensitive drums are arranged horizontally. There is a vertical arrangement configuration arranged in the vertical direction.

[0003] These features are that the horizontal arrangement has a small height but a large installation area, and the vertical arrangement has a small installation area but a high height.

[0004] In consideration of the recent desktop orientation, the number of manufacturers providing image forming apparatuses is increasing in consideration of the demand for image forming apparatuses having a vertically arranged configuration with a small installation area.

Here, a conventional image forming apparatus will be described with reference to the drawings. FIG. 3 is a longitudinal sectional view showing the entire configuration of a conventional image forming apparatus.

The image forming apparatus shown in FIG. 1 includes photosensitive drums 34 (34a, 34b, 34c, 34d) arranged in a vertical direction. Each photosensitive drum 34 is driven to rotate counterclockwise in the figure by a driving unit (not shown).

Around the photosensitive drums 34, charging rollers 35 (35a, 35b, 35c, 35d) for uniformly charging the surfaces of the photosensitive drums 34 in order according to the rotation direction, and a laser beam based on image information And irradiates each photosensitive drum 34
Scanner unit 36 (36a, 36a) for forming an electrostatic latent image on
b, 36c, 36d), a developing device 37 (37a, 37b, 37c, 37) for attaching toner to the electrostatic latent image and developing it as a toner image
d) an electrostatic transfer roller 38 (38a, 38b, 38c, 38d) for transferring the toner image on each photosensitive drum 34 to the transfer material S;
A cleaning device 39 (39a, 39b, 39c, 39) for removing transfer residual toner remaining on the surface of each photosensitive drum 34 after the transfer.
d) and the like are provided.

Here, each photosensitive drum 34 and each charging roller
35, each developing device 37 and each cleaning device 39 are integrally formed as a cartridge, and the process cartridge 40 (40a, 40a
b, 40c, and 40d), and an electrostatic transfer belt 41 that circulates and moves so as to face and contact all the photosensitive drums.

The electrostatic transfer belt 41 includes a belt drive roller 4
2, supported by four rollers, that is, driven rollers 43a and 43b and a tension roller 44, for electrostatically adsorbing the transfer material S to the outer peripheral surface on the left side in the figure, and bringing the transfer material S into contact with each photosensitive drum 34 Circular moves. As a result, the transfer material S is conveyed to the transfer position by the electrostatic transfer belt 41, and the toner image on each photosensitive drum 34 is transferred.

Each of the electrostatic transfer rollers 38 is arranged in parallel at a position in contact with the inside of the electrostatic transfer belt 41 and opposed to each of the four photosensitive drums 34. A positive charge is applied to the transfer material S from each of the electrostatic transfer rollers 38 via the electrostatic transfer belt 41, and an electric field generated by the charge causes each photosensitive drum to be charged.
The negative toner image on each photosensitive drum 34 is transferred to the transfer material S in contact with the transfer member 34.

The feeding means 45 supplies the transfer material S to the process cartridge 40 and a transfer portion for transferring the toner image to the transfer material S.
And a plurality of transfer materials S are stored in a feed cassette 46.

At the time of image formation, a feed roller 47 (half moon roller) and a retard roller pair 48 are driven and rotated in accordance with the image forming operation to separate and feed the transfer material S in the feed cassette 46 one by one. The leading end of the transfer material S abuts against the registration roller pair 49, temporarily stops, forms a loop, and synchronizes the rotation of the electrostatic transfer belt 41 and the image writing position with the registration roller pair 49 to the electrostatic transfer belt 41. It is fed.

The fixing means 50 fixes the toner image transferred to the transfer material S, and comprises a rotating heating roller 51.
a, and a pressure roller 51b which presses the transfer material S to apply heat and pressure to the transfer material S.

That is, the transfer material S onto which the toner image on each photosensitive drum 34 has been transferred is conveyed by a pair of fixing rollers 51 (51a, 51b) when passing through the fixing means 50, and is heated by the pair of fixing rollers 51. And pressure. As a result, the toner image is fixed on the surface of the transfer material S.

Next, as an image forming operation, the process cartridge 40 is sequentially driven in accordance with the image forming timing, and the photosensitive drum 34 is rotated counterclockwise in accordance with the drive. Then, each scanner unit 36 corresponding to each process cartridge 40 is sequentially driven.

By this driving, each charging roller 35 applies a uniform charge to the peripheral surface of each photosensitive drum 34, and each scanner unit 36 exposes the peripheral surface of each photosensitive drum 34 according to an image signal. Then, an electrostatic latent image is formed on the peripheral surface of each photoconductor drum. Further, developing rollers 52 (52a, 52a) in each developing device 37 are provided.
b, 52c, 52d) transfer (transfer) the toner to the low potential portion of the electrostatic latent image to form (develop) a toner image on the peripheral surface of each photosensitive drum 34.

When the leading end of the toner image on the peripheral surface of the photosensitive drum 34a at the most upstream position is rotated and conveyed to a point facing the electrostatic transfer belt 41, the image forming start position of the transfer material S is located at the point facing the point. The registration roller pair 49 starts rotating so that the transfer material S is fed to the electrostatic transfer belt 41 so that the two values coincide.

The transfer material S is pressed between the electrostatic transfer belt 41 and the electrostatic attraction roller 53 by being pressed between the electrostatic transfer belt 41 and the electrostatic attraction roller 53 while being sandwiched between the electrostatic attraction roller 53 and the electrostatic transfer belt 41. By applying a voltage therebetween, electric charges are induced in the transfer material S, which is a dielectric, and the dielectric layer of the electrostatic transfer belt 41 so that the transfer material S is electrostatically attracted to the outer periphery of the electrostatic transfer belt 41. Make up. As a result, the transfer material S is stably adsorbed to the electrostatic transfer belt 41 and is conveyed to the most downstream transfer unit.

While being conveyed in this manner, the toner image on each photosensitive drum 34 is sequentially transferred onto the transfer material S by the electric field formed between each photosensitive drum 34 and each electrostatic transfer roller 38.

The transfer material S onto which the toner image has been transferred is separated from the electrostatic transfer belt 41 by the curvature of the belt drive roller 42 and is conveyed to the fixing means 50. After the toner image is thermally fixed by the fixing unit 50, the transfer material S
Is discharged onto the discharge tray 55 with the image forming surface down.

[0021]

However, in the above-mentioned prior art, in the in-line system in which the photosensitive drums are arranged in a vertical direction, the electrostatic transfer belt is used when the jam is removed in the transfer section or when the process cartridge is replaced. Although it is necessary to retreat from the transfer portion of the process cartridge, if the transfer material S remains in the holding portion between the electrostatic transfer belt and the electrostatic attraction roller, if the transfer material S breaks or There is a possibility that the damaged parts may be damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to retreat an electrostatic transfer belt from a transfer unit when performing jam processing in a transfer unit or replacing a process cartridge. It is an object of the present invention to provide an image forming apparatus in which the transfer material S is not broken by the electrostatic attraction roller or the components are not damaged by the breakage.

[0023]

In order to achieve the above object, a typical configuration according to the present invention comprises a plurality of image carriers which are arranged in a vertical direction, and transports a transfer material in contact with the image carriers. An electrostatic transfer belt, and an electrostatic attraction roller that abuts the electrostatic transfer belt and electrostatically attracts a transfer material to the electrostatic transfer belt, wherein the electrostatic transfer belt is an image forming apparatus main body. The image forming apparatus is characterized in that it is configured to be more detachable and the electrostatic attraction roller is disposed on the image forming apparatus main body side.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the drawings.

First, the overall configuration of the image forming apparatus will be briefly described with reference to FIG. FIG. 2 is a longitudinal sectional view showing the entire configuration of the image forming apparatus according to the present invention. In the first embodiment, a full-color laser beam printer, which is one mode of an image forming apparatus, will be described.

The image forming apparatus shown in FIG. 1 has a photosensitive drum 1 (1a, 1b,
1c, 1d). Each photosensitive drum 1 is driven to rotate counterclockwise in FIG.

Around each photoconductor drum 1, a charging roller 2 (2a, 2b, 2c, 2d) for uniformly charging the surface of each photoconductor drum 1 in order according to the rotation direction, and a laser beam based on image information And irradiates each photosensitive drum 1
The scanner unit 3 (3a, 3a, 3a, 3
b, 3c, 3d), a developing device 4 (4a, 4b, 4c, 4c) for attaching toner to the electrostatic latent image and developing it as a toner image
d) an electrostatic transfer roller 5 (5a, 5b, 5c, 5d) for transferring the toner image on each photosensitive drum 1 to the transfer material S;
A cleaning device 6 (6a, 6b, 6c, 6) for removing transfer residual toner remaining on the surface of each photosensitive drum 1 after transfer
d) and the like are provided.

Here, each photosensitive drum 1, each charging roller 2, each developing device 4, and each cleaning device 6 are integrally formed as a cartridge, and the process cartridges 7 (7a, 7a) are formed.
b, 7c, 7d).

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

Each photosensitive drum 1 is formed by applying an organic photoconductor layer (OPC photosensitive member) to an outer peripheral surface of an aluminum cylinder having a diameter of, for example, 30 mm. Photoconductor drum 1
Is rotatably supported at both ends by a support member, and is driven to rotate counterclockwise in FIG. 1 by transmitting a driving force from a driving motor to one end.

A charging device of a contact charging type can be used. The charging member is a conductive roller formed in the shape of a roller. The charging roller 2 is brought into contact with the surface of each photosensitive drum 1, and a charging bias voltage is applied to this roller to thereby charge each photosensitive drum 1. The surface is charged uniformly.

Each scanner unit 3 is arranged in a substantially horizontal direction of each photosensitive drum 1, and image light corresponding to an image signal is rotated at a high speed by a scanner motor (not shown) by a laser diode (not shown). The light is irradiated to the polygon mirror 8 (8a, 8b, 8c, 8d).

The image light reflected on each polygon mirror 8 is
The surface of each charged photosensitive drum 1 is selectively exposed through each of the imaging lenses 9 (9a, 9b, 9c, 9d) to form an electrostatic latent image.

The developing devices 4a, 4b, 4c, and 4d respectively store yellow, magenta, cyan, and black toners.

A circulating electrostatic transfer belt 11 is provided so as to face and contact all the photosensitive drums 1. The electrostatic transfer belt 11 is a belt composed of a film-like member having a peripheral length of about 780 mm and a thickness of 150 μm having a volume resistivity of 10 ¹¹ to 10 ¹⁴ Ω · cm.

The electrostatic transfer belt 11 is supported by four rollers in the vertical direction. The transfer material S is electrostatically attracted to the outer peripheral surface on the left side of the drawing to make the transfer material S contact the electrostatic transfer belt 11. Circular moves. Thereby, the transfer material S is transferred to the electrostatic transfer belt.
The toner image on each photosensitive drum 1 is transferred to the transfer position by 11.

The electrostatic transfer belt 11 contacts the inside of the
Each electrostatic transfer roller 5 is provided in parallel at a position facing each of the photosensitive drums 1. A positive charge is applied from each of the electrostatic transfer rollers 5 to the transfer material S via the electrostatic transfer belt 11, and an electric field generated by the charge causes the transfer material S in contact with each of the photosensitive drums 1 to charge the photosensitive material S with the photosensitive material. The negative toner image on the body drum 1 is transferred.

The electrostatic transfer belt 11 is a belt drive roller 1
2. It is stretched over four rollers, that is, driven rollers 13a and 13b and a tension roller 14, and rotates clockwise in the figure. As a result, the electrostatic transfer belt 11 circulates and a toner image is transferred onto the transfer material S while the transfer material S is being conveyed from the driven roller 13a side to the belt drive roller 12 side.

The feeding means 15 feeds the transfer material S to a transfer section for transferring the transfer material S, and a plurality of transfer materials S are stored in a feed cassette 16.

At the time of image formation, the feed roller 17 (half-moon roller) and the retard roller pair 18 are driven and rotated in accordance with the image forming operation to separate and feed the transfer material S in the feed cassette 16 one by one. The leading end of the transfer material S collides with the registration roller pair 19, temporarily stops, forms a loop, and synchronizes the rotation of the electrostatic transfer belt 11 with the image writing position, and the registration roller pair 19 causes the transfer to the electrostatic transfer belt 11. It is fed.

The fixing means 20 fixes the toner image transferred to the transfer material S, and comprises a rotating heating roller 21.
a, and a pressure roller 21b which presses the transfer material S to apply heat and pressure to the transfer material S.

That is, the transfer material S onto which the toner image on each photosensitive drum 1 has been transferred is conveyed by the fixing roller pair 21 (21a, 21b) when passing through the fixing means 20, and is heated by the fixing roller pair 21. And pressure. As a result, the toner image is fixed on the surface of the transfer material S.

Next, as an image forming operation, the process cartridges 7 are sequentially driven in accordance with the image forming timing, and the photosensitive drum 1 is rotated counterclockwise in accordance with the driving. Then, each scanner unit 3 corresponding to each process cartridge 7 is sequentially driven.

By this driving, each charging roller 2 applies a uniform electric charge to the peripheral surface of each photosensitive drum 1, and each scanner unit 3 exposes the peripheral surface of each photosensitive drum 1 according to an image signal. Then, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 1. Further, the developing roller 10 (10a, 10a) in each developing device 4
b, 10c and 10d) transfer (transfer) the toner to the low potential portion of the electrostatic latent image to form (develop) a toner image on the peripheral surface of each photosensitive drum 1.

At the timing when the leading end of the toner image on the peripheral surface of the photosensitive drum 1a at the most upstream position is rotated and conveyed to a point opposed to the electrostatic transfer belt 11, the image forming start position of the transfer material S is set at the opposed point. , The pair of registration rollers 19 starts rotating and feeds the transfer material S to the electrostatic transfer belt 11.

The transfer material S is pressed between the electrostatic transfer belt 11 and the electrostatic attraction roller 22 by being pressed between the electrostatic transfer belt 11 and the electrostatic attraction roller 22 while being sandwiched between the electrostatic attraction roller 22 and the electrostatic transfer belt 11. By applying a voltage therebetween, electric charges are induced in the transfer material S, which is a dielectric, and the dielectric layer of the electrostatic transfer belt 11 so that the transfer material S is electrostatically attracted to the outer periphery of the electrostatic transfer belt 11. Make up. Thereby, the transfer material S is stably adsorbed on the electrostatic transfer belt 11 and is conveyed to the most downstream transfer unit.

While being conveyed in this manner, the toner image on each photosensitive drum 1 is sequentially transferred onto the transfer material S by the electric field formed between each photosensitive drum 1 and each electrostatic transfer roller 5.

The transfer material S onto which the toner image has been transferred is separated from the electrostatic transfer belt 11 by the curvature of the belt drive roller 12 and is conveyed to the fixing means 20. After the toner image is thermally fixed by the fixing unit 20, the transfer material S
As a result, the sheet is discharged onto the discharge tray 24 with the image forming surface facing down.

Further, the configuration of the electrostatic transfer belt unit 25 and the electrostatic attraction roller 22 will be described in detail with reference to FIG.

FIG. 1 is a perspective view of an image forming apparatus having a vertical arrangement according to the present invention.

In the electrostatic transfer belt unit 25, the electrostatic transfer belt 11 includes the belt driving roller 12, the driven rollers 13a, 13
b, supported by the support frame 26 in a state of being stretched over four rollers of the tension roller 14.

The belt driving roller 12 and the driven roller
Bearings 27a, 27b, 27c and 27d are pivotally supported at both ends of the support frame 13a, and are supported by a support frame 26 with their outer peripheral surfaces exposed. Rotation shafts 28a and 28b Is provided.

Rotary bearings 29a and 29b are provided in the main body of the image forming apparatus.
, And has a slight play with respect to the rotating shafts 28a and 28b to rotatably support the electrostatic transfer belt unit 25. With this configuration, the electrostatic transfer belt 11 can have a position where it contacts the electrostatic attraction roller 22 (contact position) and a position where it separates (retreat position).

The belt driving roller 12 and the driven roller 13
The respective bent portions 30a, 30b, 30c of the main body side plate are located at positions corresponding to the respective bearings 27a, 27b, 27c, 27d pivotally supported by a.
30d (30c and 30d are not shown) are formed.

When the electrostatic transfer belt unit 25 is stored in the image forming apparatus, the shaft ends of the belt driving roller 12 and the driven roller 13a are guided by the operation of bringing the electrostatic transfer belt unit 25 close to the image forming apparatus main body. 31a, 31b, 31
The belt driving roller 12 and the driven roller are guided by an urging member (not shown) while being guided by c and 31d (31c and 31d are not shown).
Both shaft ends of 13a are urged, and each bearing 27a, 27b,
27c and 27d are bent portions 30a, 30b, 30c and 30 of the main body side plate.
It is positioned by hitting d. Further, a handle portion 32 is formed on the support frame 26, and serves as a clue for opening / closing and attaching / detaching the electrostatic transfer belt unit 25.

Next, the electrostatic attraction roller 22 is disposed on the image forming apparatus main body side, and swings in grooves 33a, 33b (33b is not shown) formed in guides 31b, 31d (31d is not shown). It is arranged. Further, it is biased and supported on the electrostatic transfer belt 11 side. The electrostatic attraction roller 22 is locked at a position separated from the electrostatic transfer belt 11 at the retracted position of the electrostatic transfer belt 11 by the guides 31b and 31d.

With the above arrangement, when the electrostatic transfer belt 11 is retracted from the transfer portion of the process cartridge 7 in the case of jam clearance in the transfer portion or replacement of the process cartridge 7, the transfer material S is transferred to the electrostatic transfer belt 11. And electrostatic suction roller
The transfer material S is not broken even if it remains in the holding portion between the transfer material S and the transfer material S.

(Other Embodiments) In the above-described first embodiment, the electrostatic transfer belt 11 is configured to be detachable by rotating with respect to the image forming apparatus main body. However, the present invention is not limited to this. Instead, for example, a configuration may be adopted in which the electrostatic transfer belt 11 can be detached by attaching and detaching it to and from the image forming apparatus.

In the first embodiment described above,
The image forming apparatus having four image carriers has been described as an example, but the present invention is not limited to this, and the image carrier may be one image carrier.
The present invention can also be applied to an image forming apparatus having a plurality other than one or four.

[0060]

As described above, according to the present invention, the electrostatic transfer belt is configured to be detachable from the image forming apparatus main body, and the electrostatic attraction roller is disposed on the image forming apparatus main body side. When the electrostatic transfer belt is retracted from the transfer unit when the jam is removed in the transfer unit or when the image carrier is replaced, the transfer material may be broken by the electrostatic attraction roller or the parts may be damaged due to the retraction. Absent.

[Brief description of the drawings]

FIG. 1 is a perspective view of an image forming apparatus having a vertical arrangement according to the present invention.

FIG. 2 is a longitudinal sectional view showing the entire configuration of the image forming apparatus according to the present invention.

FIG. 3 is a longitudinal sectional view showing the entire configuration of a conventional image forming apparatus.

[Explanation of symbols]

 S ... transfer material 1 ... photosensitive drum 2 ... charging roller 3 ... scanner unit 4 ... developing device 5 ... electrostatic transfer roller 6 ... cleaning device 7 ... process cartridge 8 ... polygon mirror 9 ... imaging lens 10 ... developing roller 11 ... Electrostatic transfer belt 12: belt drive rollers 13a, 13b: driven roller 14: tension roller 15: feeding section 16: feeding cassette 17: feeding roller 18: retard roller pair 19: registration roller pair 20: fixing means 21 ... Fixing roller pair 22 ... Electrostatic suction roller 23 ... Discharge roller pair 24 ... Discharge tray 25 ... Electrostatic transfer belt unit 26 ... Support frame 27a, 27b, 27c, 27d ... Bearing 28a, 28b ... Rotating shaft 29a, 29b ... Rotating bearing 30a, 30b, 30c, 30d: Bent portions 31a, 31b, 31c, 31d: Guides 32: Handles 33a, 33b: Grooves

Claims (2)

[Claims] A plurality of image carriers arranged in a vertical direction, an electrostatic transfer belt in contact with the image carrier and transporting a transfer material, an abutment with the electrostatic transfer belt, and the transfer material An electrostatic attraction roller for electrostatic attraction to an electrotransfer belt, wherein the electrostatic transfer belt is configured to be detachable from the image forming apparatus main body, and the electrostatic attraction roller is disposed at the image forming apparatus main body side. An image forming apparatus, comprising: 2. The electrostatic transfer belt may be configured to have a contact position for contacting the electrostatic attraction roller and a retracted position at a distance from the electrostatic attraction roller, and the electrostatic attraction roller is attached to the electrostatic transfer belt side. The image forming apparatus according to claim 1, wherein the image forming apparatus is urged and locked at a position separated from the electrostatic transfer belt at a retracted position of the electrostatic transfer belt.