JP3170411B2 - Image forming device - Google Patents

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 utilizing an electrophotographic system or an electrostatic recording system, and more particularly to a cylindrical transfer material for transferring a toner image formed on an image carrier. The present invention relates to an image forming apparatus that carries the toner image on a body and conveys the toner image to a transfer section.

[0002]

2. Description of the Related Art FIG. 4 shows an example of such an image forming apparatus.
FIG. 4 is a configuration diagram showing a multicolor laser beam printer.

The laser beam printer has a photosensitive drum 4a rotatably supported as an image carrier and rotating in the direction of the arrow. Around the photosensitive drum 4a, a primary charger 4b for uniformly charging the photosensitive drum 4a, a laser scanner unit 10 for irradiating image information on the photosensitive drum 4a and forming a latent image on the photosensitive drum 4a, a photosensitive drum A rotary developing device 5 having a plurality of developing units 5Y, 5C, 5M, and 5K for developing a latent image formed on 4a to visualize it as a toner image, and a paper feed for feeding a transfer material 2 for transferring the toner image Device 1 and photosensitive drum 4a that carries fed transfer material 2
And a transfer drum 3 that conveys the sheet to a transfer section opposed to the transfer section.

[0006] The toner image formed on the photosensitive drum 4 a is carried on the transfer material 2 carried on the transfer drum 3 in the transfer section. The transfer of the photosensitive drum 4a is completed.
After the toner remaining on the surface is removed by the cleaner 4c, the toner is again subjected to the next image forming step. By repeating this image forming process for a plurality of colors, a color image in which toner images of a plurality of colors are sequentially superimposed and transferred on the transfer material 2 on the transfer drum 3 is obtained. Thereafter, the transfer material 2 is separated from the transfer drum 3 by weakening the electrostatic attraction force by the separation charger 11, sent to the fixing device 6, where the toner image is fixed there, and then discharged outside the printer.

[0005] The loading of the transfer material 2 on the transfer drum 3 will be described with reference to FIG. A gripper 3 for gripping the leading end of the transfer material 2 is provided at a predetermined position on the outer peripheral surface of the transfer drum 3.
f, and an electrostatic attraction roller 30 is provided below the transfer drum 3 so as to be able to freely contact and separate therefrom. The transfer material 2 fed from the sheet feeding device 1 is supplied to the transfer drum 3 while being guided by a guide member 3t provided in front of the suction roller 30, and the leading end is gripped by the gripper 3f.

The transfer material 2 with the leading end gripped is conveyed with the rotation of the transfer drum 3 and enters a position between the suction roller 30 and the transfer drum 3. The suction roller 30 sandwiches the transfer material 2 between the transfer drum 3 and presses against the outer peripheral surface of the transfer drum 3, and rotates with the rotation of the transfer drum 3. The transfer material 2 is electrostatically attracted to the outer peripheral surface of the transfer drum 3 by the voltage applied in between. When a voltage is applied to the attraction roller 30, an attraction charge is induced on the transfer material 2, which is a dielectric, and on the dielectric layer on the surface of the transfer drum 3. Adsorbed.

[0007]

As described above, since a voltage is applied to the attraction roller 30 for adsorbing the transfer material, the transfer drum 3 and the transfer drum 3 are connected to each other in order to prevent electric leakage with other portions of the apparatus. The suction roller 30 is rotatably accommodated in a holder 31 made of an insulating material whose opposing portion is opened.

In order to prevent the suction roller 30 from contacting the gripper 3f, rollers 32 are attached to both ends of the suction roller 30. When the rollers 32 come into contact with both ends of the transfer drum 3, the suction roller 30 does not contact the gripper 3 f provided on the outer peripheral surface of the transfer drum 3 to be slightly retracted. Since the roller 32 is rotatably mounted on the suction roller 30, the gripper 3
When the portion f passes through the location of the suction roller 30, the suction roller 30 that does not contact the suction roller 30 does not rotate.

However, in a state where the corner of the transfer material 2 that is not gripped by the gripper 3f is raised, the suction roller 30
In this case, since the suction roller 30 is not rotating, the corner of the transfer material is caught by the suction roller 30 and, as indicated by reference numeral 2a in FIG. Breaking may occur. This tendency is particularly strong when the main body of the suction roller 30 is formed of a conductive sponge or the like.

If the transfer material 2 enters the suction roller 30 in a state where the corners of the transfer material 2 are greatly deformed due to some abnormality in the paper feeding and conveying system, the transfer material is caught on the holder 31 of the suction roller 30 and similarly. Ear breaks may occur, and in the worst case, a jam (paper jam) may occur, and transfer of the transfer material may be stopped.

A similar problem is that the transfer drum 3 has a gripper 3
This is also caused when the transfer material 2 is carried on the transfer drum 3 only by the suction charging by the suction roller 30 without f.

An object of the present invention is to provide an image forming apparatus in which a corner of a transfer material is deformed, or a corner of a transfer material gripped by a gripping member is lifted, and a portion of a suction roller disposed close to a transfer material carrier is provided. It is an object of the present invention to provide an image forming apparatus capable of preventing the transfer material from being bent or jammed even when the transfer material enters.

[0013]

The above object is achieved by an image forming apparatus according to the present invention. In summary, according to one aspect of the present invention, a cylindrical transfer material carrier, and the transfer material is brought into contact with the transfer material carrier via a transfer material and rotated by the rotation of the transfer material carrier. An image forming apparatus comprising: a cylindrical conductive material suction means for electrostatically adsorbing on the outer peripheral surface of a body, wherein the suction means includes rollers at both end portions thereof in contact with both end portions of the transfer material carrier. The roller is rotatably mounted integrally with the suction means, and the suction means is accommodated in a holder for rotatably supporting and covering the suction means, and the transfer material is held in the holder by the suction means and the transfer material carrier. An image forming apparatus is provided, wherein a guide piece for guiding in the direction of the abutting portion of the body is provided.

According to another aspect of the present invention, a transfer material having a cylindrical shape and a transfer material are contacted with the transfer material support via a transfer material, and the transfer material is rotated by the rotation thereof. An image forming apparatus comprising: a cylindrical conductive material suction means for electrostatically adsorbing on an outer peripheral surface of a carrier; wherein the suction means has rollers on both ends thereof which contact both ends of the transfer material carrier. The roller is rotatably mounted on the suction means, and the suction means is accommodated in a holder rotatably supporting and covering the suction means, and the transfer material is transferred to the holder by the suction means and the transfer material. An image forming apparatus is provided in which a guide piece that guides in the direction of a contact portion of a carrier is provided.

In any of the image forming apparatuses described above, the transfer material carrier may have a gripping member for gripping the leading end of the transfer material at one position on the outer peripheral surface.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the overall configuration of an image forming apparatus according to the present embodiment will be schematically described. Since the mechanical configuration of the entire apparatus is basically the same as the conventional image forming apparatus shown in FIG. 4, it will be described below with reference to FIG.

The image forming apparatus has a photosensitive drum 4a as an image carrier. The photosensitive drum 4a has a rotating shaft rotatably supported in the image carrier unit 4. It is rotationally driven in the direction of the arrow by the gear train. Around the photosensitive drum 4a, a primary charging device 4b, a cleaner 4c, a laser scanner unit 10, a rotary developing device 5 having a plurality of developing devices 5Y, 5C, 5M, and 5K,
It includes a sheet feeding device 1 and a transfer drum 3.

The primary charger 4b is disclosed in Japanese Patent Laid-Open No. 63-1496.
No. 69, which employs a so-called contact charging method, which includes a conductive roller. The conductive roller is brought into contact with the photosensitive drum 4a and a voltage is applied to the roller. Thus, the surface of the photosensitive drum 4a is uniformly charged.

The laser scanner section 10 has a laser diode (not shown), which receives an image signal, generates image light corresponding to the image signal, and irradiates the image light to the polygon mirror 10a. The polygon mirror 10a is rotated at a high speed by a scanner motor and reflects image light, and the reflected image light is
b and the image carrier unit 4 via the reflection mirror 10c.
Are selectively irradiated onto the photosensitive drum 4a from the exposed portion to form an electrostatic latent image on the photosensitive drum 4a.

The rotary developing device 5 has developing units for each color, that is, developing units 5M, 5C, 5Y and 5K provided with magenta, cyan, yellow and black toners. These four-color developing devices 5M to 5K are rotatably arranged around a rotation shaft 5e, and each of the developing devices 5M to 5K is linked to a rotation gear disposed on the outer periphery of a revolving gear. By rotating the center, the posture is maintained constant.

At the time of image formation, each of the developing units 5M to 5K
Rotates around the shaft 5e, and when a developing device of a color corresponding to the latent image on the photosensitive drum 4a, for example, a magenta developing device 5K, stops at a developing position facing the photosensitive drum 4a, there is a developing sleeve of the developing device 5K. After the photosensitive drum 4a is positioned so as to face the photosensitive drum 4a with a small gap (about 300 μm), the latent image on the photosensitive drum 4a is developed by the toner contained in the developing container.

In the developing device 5M for performing the development, the toner in the developing container is fed to the coating roller 5a by a feeding mechanism, and the toner is supplied to the developing sleeve 5b by the rotation of the coating roller 5a, and the developing sleeve by the blade 5c. By regulating the layer thickness of the toner on the developing sleeve 5b, a thin layer of the toner having a predetermined thickness is applied and formed on the rotating developing sleeve 5b, and a triboelectric charge is given to the toner.

At the time of development, a developing bias is applied between the developing sleeve 5b and the photosensitive drum 4a, whereby the toner on the developing sleeve 5b transfers corresponding to the latent image on the photosensitive drum 4a, and the latent image is developed. This is visualized as a toner image. The developing sleeve 5b of each of the developing devices 5M to 5K is
When the developing device is rotationally moved to the developing position, it is connected to a high-voltage power supply for developing each color provided in the apparatus main body 9, and a developing bias of a voltage selected for each color is applied to the developing sleeve 5b. .

The paper feeding device 1 has a paper feeding cassette 1 a containing a transfer material 2, and the cassette 1 a is loaded on the bottom of the apparatus main body 9. At the time of image formation, the cassette 1
The paper feed roller 1b disposed near the exit of the sheet feeder 1a rotates according to the image forming operation, and the transfer material 2
Are separated one by one and fed toward the transfer drum 3. The transfer material 2 is fed to the transfer drum 3 via the registration roller 1e while being guided by the guide plate 1c at the exit of the cassette 1a.

The transfer drum 3 winds the fed transfer material 2 and transfers the toner images of the respective colors sequentially formed on the photosensitive drum 4 a onto the transfer material 2.
The transfer material 2 is rotated in the direction of the arrow at the same speed as the peripheral speed of a, and is conveyed toward the image transfer section facing the photosensitive drum 4a.

At a predetermined position on the outer peripheral surface of the transfer drum 3, a gripper 3f for gripping the leading end of the transfer material 2 fed from the paper feeding device 1 is provided. An electrostatic attraction roller 30 is provided so as to be able to freely contact and separate. The transfer material 2 fed from the sheet feeding device 1 is supplied to the transfer drum 3 while being guided by a guide member 3t provided in front of the suction roller 30, and the leading end is gripped by the gripper 3f.

The transfer material 2, whose leading end is gripped, is conveyed with the rotation of the transfer drum 3 and rushes into a portion between the suction roller 30 and the transfer drum 3. The suction roller 30 sandwiches the transfer material 2 between the transfer drum 3 and presses the transfer material 2 against the outer peripheral surface of the transfer drum 3. The transfer material 2 is electrostatically attracted to the outer peripheral surface of the transfer drum 3 by the voltage applied in between. When a voltage is applied to the attraction roller 30, an attraction charge is induced between the transfer material 2, which is a dielectric material, and the dielectric layer on the surface of the transfer drum 3. Adsorbed.

The fixing device 6 includes a pressure roller 6 that is driven to rotate.
a, and a fixing roller 6b that presses the transfer material 2 to apply heat and pressure thereto. The transfer material 2 peeled off from the transfer drum 3 and sent to the fixing device 6 passes through the fixing device 6 by being transported by the pressure roller 6a, and at the same time, receives heat and pressure from the fixing roller 6b when passing therethrough. The toner image is fixed. The cleaning member 6c is in contact with the fixing roller 6b, and the toner attached to the fixing roller 6b is removed by the cleaning member 6c.

The cleaner 4c is for cleaning and removing the toner remaining on the photosensitive drum 4a after transferring the toner image on the photosensitive drum 4a onto the transfer material 2. In this example, the waste toner removed by the cleaner 4c is conveyed to a waste toner container (not shown) attached to a side surface of the apparatus main body 9 and collected. The transport of the waste toner is performed by a transport screw 4d in the unit 4 inserted into the waste toner container.
Done by A waste toner container that is full of waste toner is removed and replaced.

In FIG. 4, reference numeral 3n denotes a charge removing roller for removing charge from the surface of the transfer drum 3.

The image forming operation of the image forming apparatus having the above configuration will be described. First, the feed roller 1b shown in FIG. 4 is driven to rotate to separate the transfer material 2 in the sheet cassette 1a. To the transfer drum 3. The transfer drum 3 rotates in the direction of the arrow in the figure, grips the leading end of the transfer material 2 fed thereto with the gripper 3f, and electrostatically attracts the transfer material 2 to its peripheral surface by the action of the attraction roller 30.

In synchronization with the rotation of the transfer drum 3, the photosensitive drum 4a is driven to rotate in the direction of the arrow in FIG.
Thus, the surface of the photosensitive drum 4a is uniformly charged, and the scanner unit 10 irradiates the image light of the magenta image to form a latent image of the magenta image on the photosensitive drum 4a. Simultaneously with the formation of the latent image, the magenta developing device 5M is driven to apply a developing bias having the same polarity as the charging polarity of the photosensitive drum 4a and substantially the same potential so that the magenta toner adheres to the latent image formed on the photosensitive drum 4a. When the latent image is developed by applying the voltage, a magenta toner image is formed on the photosensitive drum 4a. When a transfer voltage of magenta toner reverse polarity is applied to the transfer drum 3 via the shaft 3e, the magenta toner image on the photosensitive drum 4a is transferred onto the transfer material 2 held on the transfer drum 3.

When the transfer of the magenta toner image is completed as described above, the next developing units 5C, 5Y and 5K rotate and are sequentially positioned at the developing positions opposed to the photosensitive drum 4a, and similarly, cyan and yellow. The formation of a black latent image, the development, and the transfer of the toner image onto the transfer material 2 are sequentially performed, and a color image in which four color toner images are superimposed on the transfer material 2 is formed.

Transfer material 2 after transfer of four color toner images
Is separated from the transfer drum 3 by a transfer material separating member 3u and sent to a fixing device 6, where the toner image is fixed by the fixing device 6, and then discharged to a discharge tray 8 on a cover provided on an upper portion of the apparatus main body. The sheet is discharged by the roller 7, and a series of image forming operations ends here. The transfer drum 3 from which the transfer material 2 has been separated is subjected to surface charge elimination by the charge elimination roller 3n, and is initialized to a potential, so as to be ready for the next transfer material adsorption.

Next, the detailed structure and operation of the suction roller in the present invention will be described in detail with reference to FIG.

In FIG. 1, the suction roller 30 is
0a and a conductive sponge layer 30b coated thereon. Adsorption rollers 30 are provided at both ends of the core bar 30a.
A roller 32 is attached to prevent the contact with the gripper 3f. The roller 32 is made of a material that does not cause significant slippage when it comes into contact with the end of the transfer drum 3, for example, rubber. In order to prevent electric leakage from the other parts of the apparatus, the roller 3 is placed in a holder 31 made of an insulating material having an open part facing the transfer drum 3.
The entirety of the suction roller 30 including the roller 2 is rotatably housed and covered.

In the present embodiment, the roller 32 is
The roller 32 is integrally fixed to the core metal 30a, and the roller 32 rotates integrally with the suction roller 30.

Accordingly, when the attraction roller 30 is brought into contact with the transfer drum 3 for electrostatic attraction of the transfer material 2, the attraction roller 3
0 indicates that the conductive sponge layer 30b contacts the transfer drum 3, the roller 32 contacts both ends of the transfer drum 3, and the suction roller 30 and the roller 32 rotate according to the rotation of the transfer drum 3. . When the gripper 3f reaches the position of the suction roller 30 due to the rotation of the transfer drum 3, the gripper 3f is slightly retracted and provided on the outer peripheral surface of the transfer drum 3.
f. At this time, the roller 32 is
Since the roller 32 is fixedly installed on the core 32 a, the suction roller 30 also rotates together with the roller 32.

Therefore, even if the corners of the transfer material 2 gripped by the gripper 3f are raised, the transfer material 2 will protrude into the suction roller 30 rotating in the transport direction. Corners are not caught by the suction roller 30, and the occurrence of edge breaks at the corners is prevented.

In the above description, the suction roller 30 and the roller 32 are separately formed and integrated, but the roller 32 is made of the same material as the conductive sponge layer 30b of the suction roller 30, and the conductive roller 30 is formed on the core metal 30a. The sponge layer 30b and the roller 32 may be molded together. A similar effect is obtained, and there is also an advantage that the configuration of the suction roller 30 having the rollers is simplified.

Another embodiment of the present invention will be described.

FIG. 2 is a view showing a suction roller according to another embodiment of the present invention, and FIG. 3 is a view showing the configuration of an image forming apparatus incorporating the suction roller of FIG. In the present embodiment, the rollers 32 at both ends of the suction roller 30 are, as in the prior art,
Is mounted on the suction roller 30 for rotation.
A major feature is that a plurality of transfer material guide ribs 31a are formed on the transfer material entry side of the holder 31 that supports the transfer material. The mechanical configuration of the entire image forming apparatus is basically the same as that of the conventional image forming apparatus shown in FIG. 3, the same reference numerals as those shown in FIG. 4 indicate the same members.

Transfer material 2 whose end is gripped by gripper 3f
However, when the sheet enters the suction roller 30 in a state in which the corner is largely deformed due to some abnormality in the paper feed conveyance system, the transfer material is caught on the holder 31 of the suction roller 30, and similarly, the ear breakage occurs. In the case of (1), a jam (paper jam) may occur and the transfer of the transfer material may be stopped. In this embodiment, since the transfer material guide ribs 31a are formed on the transfer material entry side of the holder 31, the transfer material 2 enters the nip portion between the suction roller 30 and the transfer drum 3 without contacting the guide ribs 31a in a normal state. However, if the corner portion is greatly deformed and enters, the corner portion is
Deformation is corrected by contacting the transfer roller 1a, and enters the nip portion between the suction roller 30 and the transfer drum 3 while being guided.

Therefore, even if the corner of the transfer material 2 is greatly deformed and enters the suction roller 30, it is possible to prevent the occurrence of a broken ear or a jam.

Although the embodiments of the present invention have been described above, the above embodiments and the present embodiment may be carried out independently or in combination.
When used together, the effect of preventing the transfer material from breaking the ears and the like is further improved.

[0046]

As described above, according to the present invention, the transfer material is transferred to the cylindrical transfer material support while the transfer material is in contact with the transfer material support via the transfer material and is rotated by the rotation thereof. An image forming apparatus comprising: a cylindrical conductive material suction means for electrostatically adsorbing on an outer peripheral surface of a material carrier; (A) the suction means abuts both ends of the transfer material carrier at both ends thereof A roller, and the roller is rotatably mounted integrally with the suction means, and the suction means is accommodated in a holder which rotatably supports and covers the suction means, and holds the transfer material in the holder with the suction means and the transfer material carrier. Or (B) the suction means is provided with rollers at both ends thereof which are in contact with both ends of the transfer material carrier, and the rollers are suction means. It is installed rotatably on the It is housed in a holder that rotatably supports and covers, and the holder is provided with a guide piece that guides the transfer material in the direction of the abutting portion between the suction means and the transfer material carrier, so that the gripper grips the transfer material. Even if the transferred transfer material enters the suction roller in a state in which the transfer material is greatly deformed, it is possible to prevent the transfer material from being caught on the holder, thereby preventing the transfer material from being bent or jammed. .

[0047]

[Brief description of the drawings]

FIG. 1 is a plan view showing a suction roller in an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating a suction roller in another embodiment of the image forming apparatus of the present invention.

FIG. 3 is a configuration diagram illustrating an image forming apparatus including the suction roller of FIG. 2;

FIG. 4 is a configuration diagram illustrating a conventional image forming apparatus.

FIG. 5 is a perspective view showing a state near a transfer drum installed in the image forming apparatus of FIG. 4;

[Explanation of symbols]

 Reference Signs List 3 transfer drum 3f gripper 30 suction roller 30a core metal 30b conductive sponge layer 31 holder 31a guide rib 32 roller

Claims (4)

(57) [Claims] 1. A transfer material having a cylindrical shape, which abuts on the transfer material support via a transfer material and is rotated by the rotation of the transfer material while rotating the transfer material on the outer peripheral surface of the transfer material support. In an image forming apparatus comprising: a cylindrical conductive material suction means for performing electroadsorption, the suction means includes, at both ends thereof, rollers which are in contact with both ends of the transfer material carrier, and the rollers include the suction means. The suction means is rotatably installed integrally, and is housed in a holder which rotatably supports and covers the suction means, and transfers the transfer material to the holder in a contact portion direction between the suction means and the transfer material carrier. An image forming apparatus provided with a guide piece for guiding. 2. The image forming apparatus according to claim 1, wherein the transfer material carrier has a gripping member for gripping a leading end of the transfer material at a position on an outer peripheral surface. 3. A cylindrical transfer material carrier, and the transfer material rests on the outer peripheral surface of the transfer material carrier while being in contact with the transfer material carrier via the transfer material and being rotated by the rotation thereof. In an image forming apparatus comprising: a cylindrical conductive material suction means for performing electroadsorption, the suction means includes a roller at both ends thereof in contact with both ends of the transfer material carrier, and the roller includes the suction means. Is installed rotatably in the, and said adsorption means,
The transfer member is rotatably supported and accommodated in a holder that covers the transfer member, and the holder is provided with a guide piece that guides the transfer material toward the contact portion between the suction unit and the transfer material carrier. Image forming apparatus. 4. The image forming apparatus according to claim 3, wherein the transfer material carrier has a gripping member for gripping a leading end portion of the transfer material at a position on an outer peripheral surface.