JP2003091181A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an image forming apparatus and to improve efficiency to recover residual toner on a photoreceptor so as to prevent an abnormal image from being produced. SOLUTION: Transfer linear velocity is decided so that the linear velocity ratio of the linear velocity of the photoreceptor 1 on which a toner image is formed to the linear velocity of recording paper moving in a transfer nip part between the photoreceptor 1 and a transfer roller 7 by means of the roller 7 may be 1:1.01 to 1.03. Toner left after transfer is decreased to improve ability to recover the toner left after transfer on a developing roller 3. Furthermore, by using spherical toner (circularity is >=0.97) produced by a polymerization method and having a small particle size and high uniformity, the efficiency to transfer the toner to transfer paper is increased and nearly perfect transfer is realized. Thus, the toner left after transfer is decreased, so that the ability to recover the toner left after transfer on the developing roller is drastically improved, and the abnormal image caused by faulty cleaning is prevented.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a facsimile machine, a copying machine, a printer and the like, and has no cleaning mechanism for a transfer residual toner (developer) in an electrophotographic system. The present invention relates to an image forming apparatus called a cleanerless image forming apparatus. 2. Description of the Related Art In a conventional image forming apparatus using an electrophotographic system, a charged image carrier (photoconductor) is exposed to light according to an image signal by a laser or LED light source and statically. An electrostatic latent image is formed. Thereafter, the image is visualized by a developing unit that stores a developer (toner), the toner image is transferred by a transfer unit to a recording sheet of a material to be transferred, and the toner image transferred to the recording sheet passes through a fixing unit to form an image. finish. In the above process, the residual toner not transferred to the recording paper by the transfer means is cleaned by a cleaning device, and in the next charging step, the toner on the photoconductor is almost completely removed. However, the removal of toner by this cleaning is not complete, and a small amount of remaining toner comes into contact with the developing roller. In recent years, there has been a strong demand for downsizing of the apparatus. To meet this demand, for example, a single apparatus is used as a developing apparatus and a cleaning apparatus. Have been proposed that can simultaneously execute the same by the same means. As a result, it is possible to realize a device that is small in size and has no waste toner, eliminates a charging unit for collecting waste toner, and generates less ozone. This method is generally called a cleaner-less method, in which a single developing device develops the electrostatic latent image and cleans remaining toner after the transfer during the first passage of the electrostatic latent image. And at the same time. However, the cleaner-less image forming apparatus having such a configuration remains on the photoreceptor without being transferred to the recording paper after the image forming process due to the miniaturization. There is a problem that the toner may not be sufficiently collected in the developing and cleaning unit, and the toner on the photoreceptor that has not been completely collected is transferred to a recording sheet at the time of forming the next image, resulting in an abnormal image. Was. SUMMARY OF THE INVENTION The present invention is directed to solving the above-mentioned problems of the prior art, in which the size of the apparatus is reduced, the efficiency of collecting residual toner on the photoreceptor is improved, and the occurrence of abnormal images is prevented. It is an object to provide an image forming apparatus. In order to achieve this object, an image forming apparatus according to the present invention is directed to an image carrier for carrying an image and an electrostatic latent image formed on the image carrier. Developing means for supplying a developer to the electrostatic latent image to develop the electrostatic latent image, and simultaneously removing residual developer on the image carrier; and a developer visualized by the developing cleaning means. An image forming apparatus comprising: a transfer unit configured to transfer an image onto a transfer material, wherein a transfer speed of a transfer roller of the transfer unit and a linear velocity of the image carrier is used to transfer the developer image on the image carrier to the transfer material. The relationship between the linear speed of the transfer material and the linear speed of the image bearing member is defined as 1:
1.01 to 1.03, and a polymerized toner having a roundness of 0.97 or more is used as the developer. As a result, the transfer rate of the developer to the recording paper can be improved, the transfer residual toner can be reduced, the ability of the developing roller to recover the transfer residual developer can be improved, and a stable image can be obtained without the influence of the transfer residual developer. Quality can be obtained and the size of the device can be reduced. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the photoreceptor 1 is charged to a constant potential, and the potential decreases in an exposed portion irradiated with a light beam from a light source.
The charging brush roller 2 of the charging means has a function of charging the photoconductor 1 to a constant potential. The developing roller 3 irradiates a portion of the electrostatic latent image formed on the photoconductor 1, that is, a beam light. Toner (developer)
To form a toner image. The toner in the toner tank is supplied to the developing roller 3 by the toner replenishing roller 4. The agitator 5 prevents the toner in the toner tank from being agitated and hardened. It is preventing. Further, the developing blade 6 regulates the thickness of the toner layer on the developing roller 3 to a constant thickness, and applies a charge to the toner. The transfer roller 7 has a function of transferring the toner image formed on the photosensitive member 1 to recording paper. The operation of forming an image in the embodiment having the above-described configuration will be described with reference to FIG. The photoconductor 1 is charged to a constant voltage by the charging brush roller 2. A portion corresponding to the image signal is exposed by a light beam from an optical unit (not shown), and an electrostatic latent image is formed on the photoconductor 1. Thereafter, toner is adhered to the electrostatic latent image by the developing roller 3 in the developing and cleaning means to form a visualized toner image. The timing is controlled so that the leading end of the toner image on the photosensitive member 1 and the leading end of the recording paper coincide with each other on the recording paper conveyed from a paper feeding unit (not shown). The upper toner image is transferred to recording paper.
The recording paper onto which the toner image has been transferred is further sent to a fixing device (not shown), where the recording paper is pressed and heated, after which the formed image is fixed and discharged. Further, the photosensitive member 1 is not transferred to the recording paper side.
The transfer residual toner remaining on the surface is collected by the developing roller 3 at the developing nip formed at the contact portion between the developing roller 3 and the photosensitive member 1 by the amount of charge charged by the charging brush roller 2 that has passed first. Is done. At the same time, the developing roller 3 supplies toner to a portion of the electrostatic latent image formed on the photoreceptor 1 by the light beam to form a toner image. In the present embodiment, as shown in FIG. 1, the linear velocity of the photosensitive member 1 on which the toner image is formed
The linear velocity ratio between the linear velocity of the recording paper and the linear velocity of the recording paper moved by the transfer roller 7 at the transfer nip portion of the transfer roller 7 is 1: 1.01-1.
The transfer linear velocity is determined so that 03 (photoconductor linear velocity <recording paper linear velocity). As a result, the transfer rate of the toner to the recording paper can be improved, the transfer residual toner can be reduced, and the ability of the developing roller 3 to collect the transfer residual toner can be improved. Can be obtained. Here, the recovering ability of the developing roller between the two-component toner and the one-component toner will be described. The two-component system is a developer composed of a toner and a carrier, and the one-component system is a developer composed of only a toner. For this reason, the recovery ability of the one-component toner in the developing roller is larger than that of the two-component toner.
Therefore, it is suitable for the image forming apparatus to use a one-component toner having a high collecting ability in the developing roller, and it is possible to collect even if the amount of the transfer residual toner is large, and it is possible to collect the residual toner. A stable image quality can be obtained without any influence. Further, the toner can be classified into a “pulverization method” and a “polymerization method” according to the production method. The toner of the pulverization method is a powder having a particle diameter of about 10 μm (roundness of 0.97 or less). On the other hand, the toner of the polymerization method is manufactured by chemically aggregating and fusing the fine particle resin of the emulsion-polymerized product, the pigment and the wax, and easily making the particle diameter as small as 7 μm or less, and as small as several microns. And a highly uniform spherical toner (circularity of 0.97 or more) can be formed, and the particle size and composition become uniform. FIG. 2 is a diagram showing a comparison of the transfer ratio between the polymerized toner and the pulverized toner used in the present embodiment. As shown in FIG. 2, the transfer rate is significantly improved as compared with the conventional pulverized toner, and the transfer rate of the polymerized toner can be at least 98%. Based on the above, the linear velocity ratio between the photosensitive member and the recording paper is 1: 1.01 to 1.03, and the toner has a circularity of 0.
By using a polymerized toner of 97 or more, the transfer efficiency of the toner to the transfer paper is increased to achieve substantially perfect transfer, and the transfer residual toner is reduced, and the ability to collect the transfer residual toner in the developing roller can be greatly improved. In addition, it is possible to prevent occurrence of an abnormal image due to defective cleaning or the like. As described above, according to the present invention,
The size of the image forming apparatus can be reduced, the transferability can be improved, the transfer residual toner can be reduced, the ability of the developing roller to collect the transfer residual toner can be improved, and stable image formation can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a transfer rate between a polymerized toner and a pulverized toner used in the embodiment of the present invention. [Description of Signs] 1 Photoconductor 2 Charging brush roller 3 Developing roller 4 Supply roller 5 Agitator 6 Developing blade 7 Transfer roller

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Claims (1)

Claims: 1. An image carrier for carrying an image, a latent image forming means for forming an electrostatic latent image on the image carrier, and a developer supplied to the electrostatic latent image. An image forming apparatus including: a developing and cleaning unit that simultaneously develops and removes a residual developer on the image carrier; and a transfer unit that transfers a developer image visualized by the developing and cleaning unit to a material to be transferred. In order to transfer a developer image on the image carrier to a material to be transferred, the relationship between the linear speed of the image carrier and the linear speed of a material to be transferred by a transfer roller of the transfer unit is represented by an image carrier line An image forming apparatus, wherein a polymer toner having a circular speed of 0.97 or more is used as the developer at a speed of 1: 1.01 to 1.03 and a linear speed of a material to be transferred.