JP4723950B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that has a plurality of image carriers and secondary transfer a superposed toner image obtained by sequentially transferring toner images on the plurality of image carriers onto an intermediate transfer member collectively onto a transfer material. .

In a color image forming apparatus having an intermediate transfer member such as an intermediate transfer belt, toner and a primary transfer roller made of a foamed resin material are disposed on the back surface of the intermediate transfer member facing the image carrier (photosensitive member). By applying a voltage of reverse polarity, the toner image on the image carrier is transferred onto the intermediate transfer member, and then the toner images of the respective colors are overlapped in the same manner onto the paper as a transfer material at the secondary transfer portion. It is configured to transcribe.
Primary transfer rollers with a foamed resin material on the surface are widely used because they can be manufactured at low cost, but because the surface has fine irregularities, transfer unevenness occurs due to unevenness of the surface of the foamed resin material. There is a problem of end up.
In addition, foreign matter such as dust and dust including fine powders such as developer and paper dust enter and remain attached to the recesses on the surface of the primary transfer roller. If foreign matter adheres to the foamed resin material recess on the surface of the primary transfer roller, when a voltage is applied to the primary transfer roller in order to transfer the toner image on the image carrier onto the intermediate transfer belt, The applied voltage causes the current flowing in the primary transfer portion to concentrate on the foreign matter described above, and discharge occurs at the foreign matter attachment portion, resulting in disturbance of the toner image and image defects such as dust and omission. There is a problem of end.
Therefore, for example, in the technique described in Patent Document 1, a powder application roller is provided so as to abut the transfer roller, and a material obtained by pulverizing a material having the same characteristics as the transfer roller member using the powder application roller is formed on the surface of the transfer roller. It is applied to eliminate unevenness on the surface of the transfer roller to prevent uneven transfer.
Further, for example, in the technique described in Patent Document 2, the powdered resin recess on the surface of the primary transfer roller is filled with a lubricating powder, and foreign substances such as developer and paper powder enter the resin foam recess on the surface of the primary transfer roller. Prevent entry.
Japanese Patent Application Laid-Open No. 07-191525 JP 2004-101755 A

However, in the case of the technique described in Japanese Patent Application Laid-Open No. 07-191525, when the powder to be applied is consumed, it becomes necessary to refill the powder or replace the powder application mechanism, resulting in an increase in cost. In addition, it is not preferable in terms of environment.
In the case of the technique described in Japanese Patent Application Laid-Open No. 2004-101755, the powder filled in the concave portion gradually falls due to vibration and load as the image forming apparatus continues to operate, and foreign matter adheres to the concave portion. It will come in. Although it is possible to prevent foreign matter from adhering to the primary transfer roller at the initial operation of the image forming apparatus, it becomes impossible to suppress the adhesion of foreign matter over time, and it is necessary to replace the primary transfer roller. It will be up.
In the present invention, when the powder is applied to the surface of the primary transfer roller made of the foamed resin material by the powder application mechanism, it is necessary to refill the powder or replace the application mechanism when the applied powder is consumed. An object of the present invention is to provide a non-image forming apparatus.

In order to achieve the above object, according to the first aspect of the present invention, a toner image of each color is formed on a plurality of image carriers, and a voltage is applied to a primary transfer roller whose surface is made of a foamed resin material. A potential is generated in the intermediate transfer member, and a potential difference is created between the intermediate transfer member and the image carrier in contact with the intermediate transfer member, so that toner images on a plurality of image carriers are sequentially transferred onto the intermediate transfer member. An image forming apparatus that performs secondary transfer of a superposed toner image formed by transfer onto a transfer material collectively includes a toner application mechanism that applies toner to a primary transfer roller.
According to a second aspect of the present invention, in the first aspect, the toner application mechanism includes an application brush.
According to a third aspect of the present invention, in the first or second aspect, the particle size of the toner applied from the toner application mechanism to the primary transfer roller is smaller than the concave portion on the surface of the primary transfer roller.
According to a fourth aspect of the invention, there is provided the cleaning mechanism according to the first, second or third aspect, further comprising a cleaning mechanism for collecting the toner applied to the surface of the primary transfer roller by the toner application mechanism.
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the toner is applied to the surface of the primary transfer roller only during the time for transferring the toner image from the image carrier onto the intermediate transfer member. And a control means for controlling the toner application mechanism.
A sixth aspect of the present invention is the vibration according to any one of the first to fifth aspects, wherein the toner application mechanism vibrates so that the adhesion force of the toner applied to the surface of the primary transfer roller is increased by the toner application mechanism. A device is provided.
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the toner application mechanism is a recovered toner application mechanism that applies the toner recovered during image formation to the primary transfer roller. And

  According to the present invention, since the toner application mechanism is disposed on each primary transfer roller and the toner existing in the machine is applied to the surface of the foamed resin material of the primary transfer roller, the cost of the applied powder can be reduced. In addition, since there is no need to fill the coated powder, maintenance can be omitted.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. A toner image of each color is formed on a plurality of image carriers, a voltage is applied to a primary transfer roller whose surface is made of a foamed resin material to generate a potential on the intermediate transfer member, and the intermediate transfer member and the intermediate transfer member By creating a potential difference between the image carriers that are in contact with each other, the toner images on the plurality of image carriers are sequentially transferred onto the intermediate transfer member, and the toner images are superimposed. An image forming unit 1 that performs secondary transfer all at once is shown.
FIG. 2 is a detailed configuration diagram of the image forming unit shown in FIG. Only the configuration related to the present invention will be described together with its configuration and operation. In FIG. 2, first, a toner image formed on the image carrier 101 of the first color is applied to the back surface of the intermediate transfer belt 501 by a primary transfer roller 601 to apply a primary transfer bias having a polarity opposite to that of the toner to the intermediate transfer belt. The toner images on the image carriers 102 to 104 for the second and subsequent colors are similarly transferred onto the intermediate transfer belt 501 in a similar manner.
In the secondary transfer portion where the intermediate transfer belt 501 is sandwiched between the secondary transfer roller 600 and the opposing roller 502, a secondary transfer voltage is applied from the secondary transfer roller 600 to the paper as the transfer material, and the toner image is superimposed on the paper. (Color toner image) is transferred. Recovered toner application mechanisms 701 to 704 are disposed on the primary transfer rollers 601 to 604, respectively. Further, primary transfer portions are formed by portions of the image transfer members 101 to 104, the intermediate transfer belt 501, and the primary transfer rollers 601 to 604 that are in contact with the back surface of the intermediate transfer belt 501.
Each of the above components is controlled by a control means (CPU) (not shown).

3 to 6 are main part configuration diagrams of the image forming apparatus according to the first to fourth embodiments of the present invention. The primary transfer rollers 601 to 604 are processed by adhering a soft foamed resin material 6002 such as urethane around a metal shaft 6001 in a roller shape as shown in FIGS. The transfer belt 501 and the foamed resin material 6002 are configured to come into contact with each other, so that a primary transfer nip can be sufficiently secured.
The toner images formed on the image carriers 101 to 104 are moved from the image carriers 101 to 104 onto the intermediate transfer belt 501 by the voltage applied to the primary transfer rollers 601 to 604 at the primary transfer portion. Is done. The configuration of FIGS. 3 to 6 will be described later.
FIG. 7 is a schematic view showing a part of the surface of the primary transfer roller. The surface of the transfer roller has a fine recess 6006. Since the surface of the foamed resin material 6002 has irregularities, minute foreign matters are likely to adhere to the foamed resin material 6002.
8 to 10 are schematic views showing an enlarged portion A of FIG. While the image forming apparatus repeats the image forming operation, the foreign matter 6003 adheres from the inside and outside of the image forming apparatus to the surface of the primary transfer rollers 601 to 604 (particularly in the concave portion 6006). Assuming that a foreign material 6003 having a lower resistance than the resistance of the foamed resin material 6002 of the primary transfer rollers 601 to 604 adheres to the surface of the primary transfer rollers 601 to 604, the image transfer body 101 to 104 transfers the intermediate transfer belt during image formation. When the toner image is transferred onto the toner image 501, when the foreign material 6003 comes before and after the contact portion with the intermediate transfer belt 501, an overcurrent flows in the foreign material 6003 adhesion portion due to the voltage applied to the primary transfer rollers 601 to 604. As a result, a discharge phenomenon occurs (see FIG. 9). When the discharge phenomenon occurs, the toner image transferred onto the intermediate transfer belt 501 is disturbed, and abnormal image portions such as dust and omission are generated in the toner image.
Therefore, in the present invention, as shown in FIGS. 3 to 6, the primary transfer rollers 601 to 604 are provided with recovered toner application mechanisms 701 to 704 for applying the toner 7002 recovered during image formation. The collected toner application mechanisms 701 to 704 can store the toner 7002 therein.

In the first embodiment shown in FIG. 3, the recovered toner application mechanisms 701 to 704 are provided with a roller-shaped application brush 7001. The collected toner 7002 includes toner stored in toner collecting mechanisms (cleaning devices) 301 to 304 (FIG. 1) for collecting toner remaining on the image bearing members 101 to 104 at the time of image formation, and an intermediate transfer belt 501. The toner is stored in a toner collecting mechanism 520 that collects the remaining toner, and these toners constitute a toner storage unit (collected toner applying mechanisms 701 to 704) of the collected toner applying mechanisms 701 to 704 using a pump or the like. Case).
The application brush 7001 has various conditions such as the length, thickness, density, material, shape, rotational speed, rotational direction, contact condition, etc. of the hair so that the toner 7002 can be uniformly applied in the axial direction of the primary transfer rollers 601-604. Has been determined. Since the toner is rubbed with the application brush 7001, the adhesion force of the toner to the primary transfer roller can be improved.
The toner 7002 has a higher resistance than the 7th to the 9th power of the resistance value 10 of the foamed resin material 6002 constituting the primary transfer rollers 601 to 604. By the toner application by the recovered toner application mechanisms 701 to 704, the foamed resin material 6002 having a recess (cell diameter) of about 100 to 300 μm is filled with toner having a particle diameter of 1 to 10 μm.
In this embodiment, the collected toner is used for applying the primary transfer rollers 601 to 604, but a new toner may be used. At that time, the new toner is conveyed from the new toner storage unit storing the new toner to the toner storage unit of the collected toner application mechanisms 701 to 704 by a pump or the like.
The recovered toner application mechanism 701 to 704 applies a toner having a particle diameter smaller than the cell diameter to each surface of the primary transfer rollers 601 to 604 so that the cell diameter is filled and the primary transfer roller surface 6004 (FIG. 8 to FIG. 8). FIG. 10) is covered with toner in a film shape, and the surfaces of the primary transfer rollers 601 to 604 are smoothed.

Further, even if foreign matter 6003 such as dust or dust adheres to the surface of the primary transfer rollers 601 to 604 as shown in FIG. 10, the foreign matter 6003 is covered by the toner applied by the recovered toner application mechanisms 701 to 704 in the same manner. Also, the surfaces of the primary transfer rollers 601 to 604 are smoothed. Since the surfaces of the primary transfer rollers 601 to 604 are covered with toner, the resistance value becomes uniform, and the current flows uniformly when a voltage is applied at the primary transfer portion.
Using an image forming apparatus in which an abnormal image (image missing: an image having a small amount of toner adhesion in a toner image and looking like a spot) is generated due to a foreign matter actually attached to the primary transfer rollers 601 to 604, After applying toner onto the surfaces of the primary transfer rollers 601 to 604, an image was taken out and verified. It was confirmed that the abnormal image generated before applying the toner is not generated by applying the toner to the surface of the primary transfer rollers 601 to 604.
Here, the recovered toner application mechanism 701 is applied to the primary transfer rollers 601 to 604 only when a voltage is applied to the primary transfer rollers 601 to 604 to move the toner image from the image carriers 101 to 104 onto the intermediate transfer belt 501. A contact / separation mechanism that performs a contact / separation operation by a solenoid or the like so as to be able to contact ˜704 and control to perform the contact / separation operation in accordance with the toner application timing can suppress the toner application consumption.

In the second embodiment shown in FIG. 4, the primary transfer rollers 601 to 604 are provided with cleaning toner application mechanisms 701 to 704 and cleaning mechanisms 801 to 804. The cleaning mechanisms 801 to 804 are provided such that a blade 8001 that scrapes off excess toner applied to the primary transfer roller surface 6004 is in contact with the primary transfer rollers 601 to 604. It is housed in cleaning mechanisms 801-804. The toner can be reused by providing means such as a pump for conveying the toner collected in the cleaning mechanisms 801 to 804 to the collected toner application mechanisms 701 to 704.
By arranging the cleaning mechanisms 801 to 804 on the primary transfer rollers 601 to 604, the application amount of toner applied to the primary transfer rollers 601 to 604 from the collected toner application mechanisms 701 to 704 is always not excessive. It can be stabilized.
In the third embodiment shown in FIG. 5, the collected toner application mechanisms 701 to 704 include a vibration device 7003. The vibration device 7003 can generate vibrations in the primary transfer roller axial direction in the collected toner application mechanisms 701 to 704 using a motor or a solenoid.
Since the collected toner application mechanisms 701 to 704 are vibrated by the vibration device 7003, the toner can be rubbed against the primary transfer roller surface 6004, and the adhesion force of the toner to the primary transfer rollers 601 to 604 can be improved. .
In the fourth embodiment shown in FIG. 6, the collected toner application mechanisms 701 to 704 are installed on the upper portions of the primary transfer rollers 601 to 604, and a plurality of supply holes 7010 are formed at the bottom facing the primary transfer rollers 601 to 604. Is formed. The collected toner drops onto the surface of the primary transfer rollers 601 to 604 from the replenishment hole 7010 due to gravity and vibrations caused by the operation of the main body, so that the toner can be applied onto the surfaces of the primary transfer rollers 601 to 604.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. The detailed block diagram of the image creation part shown in FIG. 1 is a main part configuration diagram of an image forming apparatus according to a first embodiment of the present invention; FIG. 5 is a main part configuration diagram of an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a main part configuration diagram of an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a configuration diagram of a main part of an image forming apparatus according to a fourth embodiment of the present invention. FIG. 3 is a schematic diagram showing a part of the surface of a primary transfer roller. The schematic diagram which expanded and represented the A section of FIG. 3 (the 1). The schematic diagram which expanded and represented the A section of FIG. 3 (the 2). The schematic diagram which expanded and represented the A section of FIG. 3 (the 3).

Explanation of symbols

101-104 Image carrier, 501 Intermediate transfer belt (intermediate transfer member), 601-604 Primary transfer roller, 6002 Foamed resin material, 6006 Recess, 701-704 Collected toner application mechanism (toner application mechanism), 7001 Application brush, 7003 Vibration device, 801 to 804 cleaning mechanism, 8001 blade

Claims (7)

  A toner image of each color is formed on a plurality of image carriers, a voltage is applied to a primary transfer roller whose surface is made of a foamed resin material to generate a potential on the intermediate transfer member, and the intermediate transfer member and the intermediate transfer member By creating a potential difference between the image carrier and the image carrier that is in contact with each other, the toner images on the plurality of image carriers are sequentially transferred onto the intermediate transfer member, and the superimposed toner images formed on the transfer material are collectively An image forming apparatus for secondary transfer, comprising a toner application mechanism for applying toner to a primary transfer roller.   The image forming apparatus according to claim 1, wherein the toner application mechanism includes an application brush.   3. The image forming apparatus according to claim 1, wherein a particle diameter of toner applied to the primary transfer roller from the toner application mechanism is smaller than a concave portion on a surface of the primary transfer roller.   The image forming apparatus according to claim 1, further comprising a cleaning mechanism that collects toner applied to the surface of the primary transfer roller by the toner application mechanism.   2. A control unit for controlling a toner application mechanism so as to apply toner onto the surface of the primary transfer roller only during a time for transferring a toner image from the image carrier onto the intermediate transfer member. The image forming apparatus according to any one of 1 to 4.   6. The apparatus according to claim 1, further comprising a vibration device that vibrates the toner application mechanism so that the adhesion force of the toner applied to the surface of the primary transfer roller is increased by the toner application mechanism. The image forming apparatus described in the item. The image forming apparatus according to claim 1, wherein the toner application mechanism is a recovered toner application mechanism that applies the toner recovered during image formation to the primary transfer roller.

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