JP2667160B2 - Electrophotographic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus using a so-called Carlson process for copying an original image on plain paper, and more particularly, to a belt means made of a semiconductor material capable of retaining electric charges. The present invention provides a new electrophotographic apparatus having a transfer device that can stably transfer a toner image using the image forming apparatus. 2. Description of the Related Art The development of a transfer and transport device having good transferability and paper-passing properties is indispensable for realizing a stable copy function. Hereinafter, an example of an electrophotographic apparatus having a conventional transfer and transport device will be described with reference to the drawings. FIG. 5 is a front view showing the configuration of a conventional electrophotographic apparatus having a transfer and transport device. In FIG. 5, reference numeral 10 denotes a rotatable photosensitive member serving as an electrostatic latent image carrier, reference numeral 12 denotes a first charger for applying a charge to the photosensitive member 10, and reference numeral 14 denotes an electrostatic latent image on the photosensitive member 10. A developing device for supplying toner particles, a paper feeder 16 for supplying copy paper in the direction of the photoconductor 10, a copy paper 17 and a toner 18 for copy paper 17 supplied by the paper feeder 16. A second charger 20 for applying a charge having a polarity opposite to that of the particles, 20 is an AC charger to which an AC voltage is applied to remove electricity from the copy paper 17 charged by the second charger, and 22 is sent out from the photoreceptor 10 A transport belt 24 for carrying the copy sheet 17 is a fixing device for fixing the toner on the copy sheet 17 to the copy sheet 17. In FIG. 6, after the charge is uniformly applied to the rotating photoconductor 10 by the first charger 12, the original surface image is exposed through a required optical system (not shown) so that the surface of the photoconductor 10 is exposed. Then, an electrostatic latent image corresponding to the document surface image is formed. By supplying the electrostatic latent image on the surface of the developing device 10, the electrostatic latent image on the photoreceptor 10 is developed and visualized. The paper feeding device 16 supplies the copy sheet 17 in the direction of the photoconductor 10 in synchronization with the rotation of the photoconductor 10. The second charger 18 applies a uniform charge to the copy sheet 17 in conjunction with the operation of the sheet feeding device 16. Copy paper 17 by the second charger 18
Has a polarity opposite to the charging polarity of the toner particles attached to the photoconductor 10, and the charged copy paper 17 resists the surface of the photoconductor 10 and electrostatically charges. The toner particle image adhered to the surface of the photoconductor 10 and charged while being attracted is electrostatically transferred onto the copy paper 17. The AC charger 20 removes static electricity from the copy paper 17 electrostatically attracted to the surface of the photoconductor 10 and separates the copy paper 17 from the photoconductor 10 by utilizing the mechanical rigidity of the copy paper 17. Works in sync with. As the photoconductor 10 rotates, it is sent in the direction of the conveyor belt 22 while being separated from the photoconductor 10. The conveyor belt usually has an opening at a portion facing the copy sheet 17, and is configured to suck air through a fan (not shown) through the opening. The copying paper 17 is attracted to the surface of the conveyor belt 22 by the suction force of the fan, and the copying paper 17
And send it to The fixing device 24 inserts the copy sheet 17 sent by the conveyor belt 22 between two rollers,
By applying heat and pressure, the toner particles on the copy sheet 17 are melted and pressed, and the copy sheet 17 is discharged out of the apparatus while being fixed on the copy sheet. In the above-described conventional electrophotographic apparatus, a second charger 18 for providing a charge necessary for transferring a toner particle image onto a copy sheet 17 and an AC charger for erasing and removing the upper charge provided by the second charger 18 are provided. It is common to use a Colontron utilizing corona discharge for the 20 and, furthermore, the second charger 18 and the AC charger 20 are often provided close to each other due to their functions, as shown in FIG. In many cases, the charging area of the second charger 18 and the static elimination area of the AC charger 20 partially overlap each other. Problems to be Solved by the Invention In the above-described conventional electrophotographic apparatus, the toner particle image on the photoreceptor 10 is transferred to a copy sheet 17, and the copy sheet 17 is fixed to a fixing device.
There are the following problems with sending to the 24 position. First, in order to transfer the toner particle image on the photoreceptor 10 to the copy sheet 17, the copy sheet 17 needs to have an electric charge, while in order to separate the copy sheet 17 from the photoreceptor, Incorrect transfer of the toner particle image due to the necessity of performing the contradictory action that the copy paper 17 needs to be sufficiently neutralized in a very close portion, or the transfer of the copy paper 17 from the photoconductor 10 This is the occurrence of separation failure.
That is, in order to perform the transfer reliably, the voltage applied to the second charger 18 may be increased to increase the charge applied to the copy sheet 17, but then the charge removal of the copy sheet 17 by the AC charger 20 becomes insufficient. There is a danger that the copy paper 17 will not separate from the photoreceptor 10 and will roll up while adsorbed on the photoreceptor 10, and conversely, the action of the AC charger 20 must be strengthened to prevent such separation failure. Then AC Charger 20
Of the second charger 18 extends to the charging range of the second charger 18, the charging of the copy paper 17 by the second charger 18 becomes insufficient, and the transfer of the toner particle image on the photoconductor 10 to the copy paper 17 is impaired. Will be. To perform good transfer of the toner image and reliable separation of the copy paper 17 from the photoreceptor 10, it is necessary to adjust the strength of the action between the second charger 18 and the AC charger 20, but the stable area is narrow. Adjustment work is difficult. Second, the copy sheet 17 holds the charge required to transfer the toner particle image on the photoreceptor 10.
Is a problem caused by direct contact with the photoconductor 10. As described above, the second charger 18 for applying a charge to the copy sheet 17 and the AC charger 20 for removing the charge on the copy sheet 17
Are provided in close proximity to each other, so that the copy paper 17 has a second charger 18 as a charge supply source and an AC charger as a charge absorption source.
The sheet acts as an electric resistor connecting to the charger 20, and the magnitude of the electric resistance of the copy sheet 17 changes the amount of electric charge held by the copy sheet 17. Therefore, in order for the copy sheet 17 to have the required charge required for transfer,
Although it is necessary to adjust the amount of charge applied to the second charger 18 according to the magnitude of the electric resistance of 17, the type of copying paper used in the electrophotographic apparatus is not one type, and the electric resistance value is not constant. Furthermore, about one kind of copy paper,
It is well known that the electrical resistance greatly changes depending on the environment in which it is placed, especially the humidity conditions, and it is extremely difficult to maintain good toner image transfer in all environments for all types of copy paper. It is.
Further, in order to transfer the toner image, it is usually necessary to apply an electric charge whose surface potential of the copy paper 17 exceeds 2 KV. However, the copy paper 17 having such a high electric potential is a photoreceptor 10.
There is a possibility that dielectric breakdown of the photosensitive layer of the photoreceptor 10 occurs from a place where the photosensitive layer is in direct contact, and the photosensitive layer is damaged. Third, the force that separates the copy sheet 17 that has been charged by the second charger 18 and is electrostatically attracted to the photoreceptor 10 from the photoreceptor 10 depends on the mechanical rigidity of the copy sheet 17 itself. The problem is that the AC charger 20 removes the charge of the copy sheet 17 but does not apply a force for positively separating the copy sheet 17 from the photoconductor 10.
Therefore, when using thin, low-rigidity copy paper,
Even if a small amount of electric charge remains on the copy sheet, there is a high risk that poor separation of the copy sheet from the photoreceptor 10 will occur and a paper jam will occur. Further, since the copy sheet 17 is separated from the photoreceptor 10 by the rigidity of the copy sheet itself, a certain time determined by the rigidity of the copy sheet is required for separation. Therefore, the photoconductor 10
When the rotation speed of the copy paper 17 is high, the separation speed of the copy paper 17 becomes relatively slow, and the risk of separation failure occurring and paper jams increases. Fourth, since the transport force of the transport belt 22 for transporting the copy sheet 17 is generated by the suction force of the fan and the size of the opening provided in the transport belt 22, it is not necessarily strong enough. Due to the problem caused, sufficient paper conveyance force cannot be obtained for copy paper with a small empty area, such as copy paper with a small area or curled copy paper, and the copy paper cannot be transported to the fixing device 24 and paper jams often occur. . In view of the above problems, the present invention does not require an AC charger for static elimination, can perform good toner image transfer irrespective of the type of copy paper and environmental conditions in which it is placed, and forcibly exposes the copy paper after transfer. An electrophotographic apparatus provided with a new electrostatic transfer / transport device having a force of separating, holding and transporting from a body. Means for Solving the Problems In order to solve the above problems, the present invention provides an electrostatic latent image carrier, a developing unit for supplying charged toner to the electrostatic latent image carrier, and an electrostatic latent image carrier. Close to the image carrier and the specific resistance is 10
^A resistance layer made of a material of ¹⁰ to 10 ¹³ Ωcm and a specific resistance of 10
An endless belt means having a surface layer of a material of ¹⁰ Ωcm or more and made of a material from which toner is easily released, and a downstream side of a contact area between the electrostatic latent image carrier and the belt means in a copying paper supply direction. And a conductive grounding means which is disposed in the belt means from the inside, and a copy sheet is applied to the belt means at a portion immediately before the copy sheet supply direction in a contact area between the electrostatic latent image carrier and the belt means. Pressing means for pressing, and charge applying means for supplying an electric charge having a polarity opposite to the charging polarity of the toner to the belt means and disposed near the contact area inside the belt means, wherein the belt is provided on the grounding means. Means for mitigating the charge held by the means, transferring the toner with an electrostatic force acting on the copy sheet by the charge held by the belt means, and transferring the copy sheet to the electrostatic latent by the electrostatic force. Image bearer An electrophotographic apparatus characterized by being separated from a holding body. Further, the electrophotographic apparatus is characterized in that the charge applying means is a corona discharger. Further, the electrophotographic apparatus is characterized in that the resistance layer of the belt means is made of an elastic material, and the toner adhered to the surface is removed by a cleaning blade. further,
The electrophotographic apparatus is characterized in that the surface layer of the belt means is made of a material containing a fluorine resin. According to the present invention, the charge applying means has a configuration in which the charge applying means has a resistance of at least 10 ¹⁰ to 10 ¹³ Ω-cm in the vicinity of the vicinity of the belt means and the toner particle conveying means. By applying an electric charge to the first layer, the electric charge induced by the electrostatic induction of the copy sheet and the electric charge of the first layer of the belt means are not directly applied to the copy sheet fed by the sheet feeding means. The copying paper is attracted and conveyed onto the belt means by electrostatic attraction with a true charge. However, in the method using the belt, since the belt unit comes into contact with the electrostatic latent image carrier, contamination by toner cannot be avoided, and a cleaning unit is practically necessary. The cleaning unit removes the toner. A material such as a cleaning blade and a material that easily separates from the toner including a fluororesin is provided on the surface of the belt means. In this case, the material provided on the surface of the belt means may deteriorate not only the toner but also the adhesion to the copy paper. For this reason, the copy sheet may not be smoothly inserted into the contact area between the electrostatic latent image carrier and the belt means, causing paper wrinkling. In order to solve this inconvenience, in the present invention, the copy sheet is pressed against the belt means by the pressing member and electrostatically attracted before the copy sheet reaches the contact area between the electrostatic latent image carrier and the belt means. Since the belt is composed of the resistance layer and the surface layer, the charge applied to the belt means moves from the contact area toward the grounded member, and the copy sheet is also static in the contact area between the pressing member and the belt means. It can be electrically polarized and can be attracted to the belt means. Further, when the belt means is made of an elastic body, there is an advantage that the electrostatic latent image carrier and the belt means can be more securely adhered to each other. However, in this case, it is effective to remove the toner by a cleaning blade or the like, so that it is effective to provide a surface on which the toner is easily released on the surface of the belt means. By pressing the copy sheet against the belt means by the pressing member before the copy sheet is inserted into the contact area, good transfer and separation can be performed. As described above, when the copy sheet is electrostatically attracted to the belt means by the pressing member before the transfer, the transfer of the toner image and the separation of the copy sheet are reliably performed without generating wrinkles of the copy sheet. Embodiment An embodiment of the present invention will be described below with reference to the drawings for an electrophotographic apparatus. FIG. 1 is a front view showing the structure of an electrophotographic apparatus according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a main portion of the electrophotographic apparatus according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a partial front view for explaining a toner particle transfer operation of the electrophotographic apparatus. 1 and 2, reference numeral 10 denotes a rotatable photoconductor as an electrostatic latent image carrier, 11 denotes a grounded conductor provided on the back surface of the photoconductor 10, and 12 denotes a charge on the photoconductor 10. A first charger 14 for applying the toner, a developing device 14 for supplying charged toner particles to the electrostatic latent image on the photoconductor 10, and a photoconductor 16
A paper feeder for supplying copy paper in the direction of 10, 17 is copy paper, 276 is a transport belt as an endless belt means for transporting the paper 17 supplied by the paper feeder 16,
Reference numeral 28 denotes a driving roller that is driven to rotate to drive the transport belt, 30 denotes a rotatable ground roller in which a portion that contacts the inside of the transport belt 26 is a conductive portion made of an electrical conductive material, and 31 denotes a ground roller. A grounding spring for grounding the conductor portion of the roller, 32 is a winding roller for bringing the transport belt 26 into contact with the photosensitive member 10 at a required winding angle, and 34 is a charge applying means for applying an electric charge to the transport belt 26. A transfer charger 36 is a cleaning device for cleaning the surface of the transport belt 26, and 46 is a pressing member. The operation of the electrophotographic apparatus configured as described above will be described below. In FIG. 1, after the charge is uniformly applied to the rotating photoconductor 10 by the first charger 12,
By exposing the document surface image via a required optical system (not shown), an electrostatic latent image corresponding to the document surface image is formed on the photoconductor 10. Numeral 14 charges the toner particles substantially uniformly, and supplies the toner particles to the surface of the photoconductor 10, thereby developing the electrostatic latent image on the photoconductor 10 into a visible image. The paper feeding device 16 supplies the copy sheet 17 in the direction of the photoconductor 10 in synchronization with the rotation of the photoconductor 10.
The driving roller 28 is driven to rotate in conjunction with the sheet feeding device 16, and at the same time, the transfer charger 34 supplies electric charges to the transport belt 26. The transfer charger 34 is a corona discharge device formed by stretching a thin dangsten wire as a discharge body, and is disposed so that the photoconductor 10 and the discharge surface face each other through a contact point between the photoconductor 10 and the conveyor belt 26. It is configured to generate a corona by using the grounded conductor portion 11 provided on the back surface of the photoconductor 10 as a counter electrode and to apply a charge to the conveyor belt 26 in the vicinity of the contact portion with the photoconductor 10. Have been. At this time the winding roller
If 32 is made of a grounded conductor material, the winding roller 32
Can also act as a counter electrode for the discharge of the transfer charger 34, and the amount of charge that the transfer charger 34 applies to the transport belt 26 can be controlled. Since the conveyor belt 26 is made of a semiconductor material having an electric resistance of 10 ¹⁰ to 10 ¹³ Ω-cm, even if the ground roller 30 is provided, or the winding roller 32 is formed of a grounded conductive material, the electric power is not supplied. It acts as a stable resistor connecting the transfer charger 34 as a source and the ground roller 30 and the winding roller 32 as a charge relaxation source, and stably holds the power supplied from the transfer charger 34. According to measurement, transfer charger 34
When the voltage applied to the transfer belt 26 is +6.5 KV, the surface potential of the transport belt 26 is in the range of 2.5 VK to 3
kv can be obtained. The transport belt 26 is composed of a resistance layer for the purpose of retaining electric charges and a surface layer for enhancing the releasing effect of the toner. In this case, due to the effect of the surface layer of the transport belt 26, the adhesion to the copy paper 17 as well as the toner may be impaired.
For this reason, inconveniences such as paper wrinkles occur when the copy sheet 17 is nipped in the contact area between the photoconductor 10 and the conveyor belt 26. In order to avoid this, the copy sheet 17 is transported with the electric charge given from the transfer charger 34 by the pressing member 46 provided immediately before being inserted into the close place where the photoreceptor 10 and the transport belt 26 are separated. The transfer belt 26 is pressed by the belt 26, causes polarization by electrostatic induction, and is transported in close contact with the surface of the transport belt 26. The movement of the toner particles on the photoreceptor 10 to the copy sheet 17 is performed by a true charge of the transport belt 26 or an electrostatic attraction between the polarization charge of the copy sheet 17 and the charge of the toner particles. The copy paper pressing member 46 is effective in increasing the adhesion between the copy paper 17 and the conveyor belt 26, ensuring separation of the photoconductor 10 and the copy paper 17 and maintaining good transferability. is there. FIG. 3 shows the transfer operation of the toner particles.
In FIG. 3, electric charges are given to the transport belt 26 by the transfer charger 34. This charge polarizes the copy sheet 17 to generate an electrostatic attraction between the true charge on the transport belt 26 and the polarization charge of the copy sheet 17, and the copy sheet 17 is attracted to the transport belt 26. The charged toner particles on the photoconductor 10
Is attracted in the direction of the transport belt 26 by electrostatic attraction between the true charge on the transport belt or the polarized charge of the copy sheet 17 near the contact point between the transfer belt 26 and When selenium is used as the photoreceptor 10 to be transferred, it is normal that the surface potential is charged until the surface potential becomes about 800 V, and in order to overcome the selenium surface potential and transfer the toner particles, the transfer belt 26 is used. Although a surface potential of 2 KV or more is required, a high potential of 2.5 KV to 3 KV can be obtained with the transport belt of the present embodiment, and good transfer can be realized as described above. As described above, the force for transferring the toner particles on the photoreceptor 10 to the copy paper 17 is generated by the charge applied to the transport belt 26. Therefore, if the electric resistance value of the transport belt 26 is determined, stable transfer of toner particles can be maintained regardless of the type of the copy sheet 17 to be used and the environment where the copy sheet 27 is placed. Furthermore, since an AC charger for removing charge from copying paper as in the conventional example is not required and there is no component that hinders the transfer function, stable transfer of toner particles can be performed. The copy paper 17 on which the toner particles have been transferred and held from the surface of the photoreceptor 10 is conveyed in accordance with the drive of the conveyance belt 26 and is sent to the fixing device 24 while being separated from the conveyance belt 26 at the position of the ground roller 30. The transport belt 26 from which the copy paper 17 has been separated is cleaned by a cleaning device 36, and driven again to the toner particle transfer position. As the cleaning device, a method used for cleaning the photoreceptor 10 can be used, and a cleaning blade, a fur brush, and the like are useful. In the embodiment shown in FIG. 1, a cleaning blade 38 is used. The cleaning blade 38 is made of an elastic material on the back surface of the conveying belt 26 with which the cleaning blade 38 contacts, and the surface is made of a material having a small sliding resistance with the conveying belt 26. By providing the support member 40,
The state of contact of the cleaning blade 38 with the conveyor belt 26 is guaranteed, and the driving load of the conveyor belt 26 is prevented from increasing. What is important here is that the conveyor belt 26 is made of a semiconductor material having an electric resistance of 10 ¹⁰ to 10 ¹³ Ω-cm. As described above, the conveyor belt 26 needs to have a surface potential of 2 KV or more in the vicinity of the contact portion with the photoconductor 10 in order to transfer the toner particles on the photoconductor 10 to the copy sheet 17, but at the same time, After passing through the vicinity of the contact position with the photoconductor 10, it is desirable to gradually relax the retained charge. One of the reasons is that the copy paper 17 that is adsorbed and conveyed by the conveyance belt 26 must be separated from the conveyance belt 26 at the position of the ground roller 30 and sent to the fixing device 24, but is conveyed at the position of the ground roller 30. If the belt 26 still holds a high charge amount, it is difficult to separate the copy sheet 17 from the transport belt 26. Also, conveyor belt
As long as 26 performs the function of transferring to the charged toner particles, it is inevitable that the charged toner particles adhere to the surface thereof.Therefore, a cleaning device 36 is provided to clean the surface of the transport belt 26. However, if the transport belt 26 has a high charge and a strong electrostatic attraction acts between the transport belt 26 and the toner particles, it becomes difficult to stably separate and remove the toner particles from the surface of the transport belt 26. For example, if the contact pressure of the cleaning blade 38 on the transport belt 26 is increased, cleaning becomes possible, but the transport belt 26
The frictional resistance between the transfer belt 26 and the cleaning blade 38 increases, and the driving load of the transfer belt 26 increases. This causes problems such as shortening. If the transport belt 26 is made of a material having a low electrical resistance of 10 ⁹ Ω-cm or less, the ground roller 30
As a result, the electric charge required for transfer is not obtained on the surface of the conveyor belt 26. Ground roller 30
It is possible to raise the surface potential of the transport belt 26 to a required value by grounding through a high resistance of about 10 ⁸ Ω, but this reduces the charge from the transport belt 26 via the ground roller 30. This is disadvantageous because the risk of occurrence of the above-described problem increases. Also, if the electrical resistance of the transport belt 26 is reduced, the interface resistance with the copy paper 17 decreases, so that the true charge of the transport belt 26 is applied to the copy paper 17 and the copy paper 17 has the same polarity charge as the transport belt 26. As a result, it has been observed that the suction force between the copy sheet 17 and the transport belt 26 is reduced to cause a separation failure between the copy sheet 17 and the photoconductor 10 and a transport failure of the copy sheet 17, which is not suitable for practical use. Conversely, when the transport belt 26 is made of a material having a high electrical resistance of 10 ¹⁴ Ω-cm or more, the surface potential of the transport belt 26 is sufficiently high, but the electric charge from the setting roller 30 is extremely small. In addition to the above-described problem, the transfer charger 34 is
There is a problem that the surface power of the conveyor belt 26 gradually rises as the charge is added from the surface, and finally there is a risk of causing a dielectric breakdown of the photoconductor 210 in the vicinity of the contact portion with the photoconductor 10. Not suitable for practical use. As described above, in the present embodiment, the transport belt 26 is set to 10 ¹⁰ to 10
It is essential to use a semiconductor material having an electrical resistance of ¹³ Ω-cm. Further, the ground roller 30 is useful for alleviating the electric charge of the conveyor belt 26. In the present embodiment, this is also used as a driving means for stretching and driving the transport belt 26 to simplify the configuration of the apparatus, but of course, it may be provided separately from the drive means for the transport belt 16. In addition to the ground roller, use other than having a charge removing function such as a so-called charge removing brush can be considered. In this embodiment, a corona discharger is used as the transfer charger 34. There is also a method of applying a charge by energizing the conductive brush by bringing a conductive brush into contact with the conveyor belt 26 and applying a voltage to the conductive brush. When it is lowered, current flows too much from the scratched part, so-called leakage occurs, and it is difficult to maintain stable charge application, and in extreme cases, there is a risk of damaging the photoreceptor 10 and there is a risk of practical use Has a problem. When a corona discharger is used as the transfer charger 34, the conductor 11 on the back surface of the photoconductor 10 can be used as a counter electrode for corona discharge. The fact that the conveyor belt 26 is interposed between the transfer charger 34 and the photoconductor 10 does not impair the function of the corona discharger. Of course, it is possible to positively provide another counter electrode other than the conductor portion 11 on the back surface of the photoconductor 10 to adjust and control the operation of the corona discharger. In order to apply electric charges to the transport belt 26 near the contact point, it is convenient to dispose the transfer charger 34 so as to substantially face the conductor 11 of the photoconductor 10 via the transport belt 26. The corona discharger is effective in supplying electric charges to a portion close to the conveying belt 26 with a pressing means for electrostatically adhering a copy sheet 17 to the conveying belt 26, which will be described later. Further, in the present embodiment, the transport belt 26 is provided so as to partially contact the photoconductor 10, but the transport belt 26 and the photoconductor 10 do not necessarily need to be in contact with each other. The transfer of the toner particles is performed even if the toner particles are separated with a gap. At this time, since the copy sheet 17 is provided with an auxiliary means for pressing and contacting the transfer belt 26, the adhesion between the charged transfer belt and the copy sheet 17 is improved, and the transfer of toner particles and the copy sheet The separability from the photoreceptor of 17 and the transportability are improved. FIG. 4 is a main part front view showing a configuration using the transport belt 26 in which the resistance layer and the surface layer are laminated. In FIG. 4, the conveyor belt 26 is composed of a base layer 42 as a first resistance layer made of a semiconductor material having an electric resistance of 10 ¹⁰ to 10 ¹³ Ω-cm and a material having an electric resistance of 10 ¹⁰ Ω-cm or more. It has a surface layer 44 as a second layer, and the other structure is the same as that of the embodiment of FIGS. 1 and 2. The base layer 42 acts as a resistor connecting between the transfer charger 34 as a charge supply source and the ground roller 30 as a charge relaxation source, and is supplied from the transfer charger 34, similarly to the transport belt 26 in the above-described embodiment. The electric charge is stably held, and a potential necessary for transferring the toner particles on the photoconductor 10 is generated. The surface layer 44 is provided on the surface of the expected layer 42 on the side where the copy paper 17 is adsorbed, and is set to 10 ¹⁰ Ω-cm so as to effectively prevent the transfer to the charge copy paper 17 of the base layer 42. It has the above resistance. As described above, if the surface layer 44 has a resistance value equal to or more than the minimum resistance value of the base layer 42 of 10 ¹⁰ Ω · cm, the electric charge held by the base layer 42 is
The transfer belt 26 and the copy sheet 17 can be prevented from being injected into the copy sheet 17, and the transfer belt 26 and the copy sheet 17 do not cause electrostatic repulsion due to holding the same polarity charge, so that a good copy sheet 17 from the photoconductor 10 can be prevented. Separation performance can be obtained. The surface layer 44 is polarized by the true electric charge of the base layer 42, and generates an electrostatic attraction between the similarly polarized copy paper 17 and the polarized electric charge.
Is adsorbed and held on the surface layer. The toner particles on the photoreceptor 10 are attracted in the direction of the transport belt 26 by electrostatic attraction between the true charge of the base layer 43, the surface layer, and the polarization charge of the copy sheet 17, and are adsorbed on the surface layer 44 of the transport belt 26. Is transferred onto a copy sheet that has been processed. As long as the surface layer 44 has a resistance of 10 ¹⁰ Ω-cm or more, the effect of the present invention is not impaired at all, and thus the surface layer 44 is basically added to the base layer which must function as an electric resistor. By doing so, other effects can be produced. The surface layer 44 is made of a material having a low coefficient of friction with a small sliding resistance with the cleaning blade 38, thereby reducing the load at the time of driving the transport belt 26 and extending the operating life of the transport belt 26 and the cleaning blade 38. Can be. Further, by forming the surface layer 44 from a material having good releasability from toner particles, additional effects such as improvement in stability of the cleaning operation can be obtained. As a material of such a surface layer 44, polyamide, fluororesin, or the like is effective. The surface layer 44 as described above, by applying and drying a liquid paint containing the resin as described above on the surface of the base layer 42,
Alternatively, it can be formed by bonding and holding a layer on a film made of the above-mentioned material to the surface of the base layer 42. Since the conveyor belt 26 is a belt transmission driven by a driving unit, it is desirable from the viewpoint of driving stability that both the base layer 42 and the surface layer 44 are elastic bodies having elasticity. In the case of an inelastic body having no elasticity, the parallelism of the setting of the drive roller 28 and the ground roller 30 or the accuracy of the peripheral length difference between the left and right of the transport belt 26 must be increased to improve the transport belt 26.
And the drive becomes unstable. Effect of the Invention As described above, the present invention provides an electrostatic latent image carrier, developing means for supplying charged toner to the electrostatic latent image carrier, and a specific resistance close to the electrostatic latent image carrier and having a specific resistance. 10 ¹⁰ to 10 ¹³ Ωcm
Endless belt means in which a resistance layer made of the above material and a surface layer made of a material having a specific resistance of 10 ¹⁰ Ω · cm or more and easy to release the toner are laminated, and the electrostatic latent image carrier and the belt A conductive grounding means disposed downstream of the contact area with the means in the copy paper supply direction and supporting the belt means from the inside; and a conductive grounding means immediately before the copy paper supply direction in the contact area between the electrostatic latent image bearing and the belt means. A pressing unit that presses a copy sheet against the belt unit in the proximity unit; and a charge applying unit that supplies an electric charge having a polarity opposite to the charging polarity of the toner to the belt unit and is disposed inside the belt unit and near the contact area. Means for reducing the charge held by the belt means on the ground means, transferring the toner with electrostatic force acting on the copy sheet by the charge held by the belt means, and Stillness An electrophotographic apparatus, wherein the copy sheet is separated from the electrostatic latent image carrier by electric power, further, an electrophotographic apparatus, wherein the charge applying means is a corona discharger, An electrophotographic apparatus, wherein the resistance layer of the belt means is made of an elastic body, and toner adhered to the surface is removed by a cleaning blade; and the surface layer of the belt means is made of a material containing a fluororesin. According to the electrophotographic apparatus, a good copy image without image disturbance can be obtained.
When the copy sheet is electrostatically attracted to the belt means by the pressing member until the copy sheet reaches the contact area between the electrostatic latent image carrier and the belt means, the surface of the belt means can easily release the toner image, for example. , A good copy image can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing a configuration of an electrophotographic apparatus according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a main part of the electrophotographic apparatus according to the embodiment of the present invention, FIG. FIG. 4 is a partial front view for explaining the transfer operation of the toner particles of the electrophotographic apparatus in the embodiment of the present invention, FIG. 4 is a front view showing the structure of the belt means in the embodiment of the present invention, and FIG. FIG. 1 is a front view illustrating a configuration of an example of an electrophotographic apparatus. 10 photoconductor, 11 conductor, 12 charger No. 1,
14 ... Developer, 16 ... Paper feeder, 17 ... Copy paper, 18 ...
... No. 2 charger, 20 ... AC charger, 22 ... Conveyor belt, 24 ... Fixer, 26 ... Conveyer belt, 28 ... Drive roller, 30 ... Ground roller, 31 ... Ground spring, 32 ... Winding roller 34 Transfer charger 36 Cleaning device 38 Cleaning blade 40 Supporting member 42 Base layer 44 Surface layer 46 Pressing member.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Akira Kumon               1006 Kadoma Kadoma Matsushita Electric Industrial               Inside the corporation                (56) References JP-A-54-58034 (JP, A)                 JP-A-57-172369 (JP, A)

Claims (1)

(57) [Claims] An electrostatic latent image carrier, developing means for supplying charged toner to the electrostatic latent image carrier, and a material having a specific resistance of 10 ¹⁰ to 10 ¹³ Ωcm close to the electrostatic latent image carrier. Endless belt means in which a resistance layer having a specific resistance of 10 ¹⁰ Ωcm or more and a surface layer made of a material from which toner is easily released is laminated, and the electrostatic latent image carrier and the belt means are A conductive grounding means disposed downstream of the contact area in the copy paper supply direction and supporting the belt means from the inside, and a proximity portion of the contact area between the electrostatic latent image carrier and the belt means immediately before the copy paper supply direction. A pressing unit for pressing a copy sheet against the belt unit; and a charge applying unit that supplies a charge having a polarity opposite to the charging polarity of the toner to the belt unit and is disposed inside the belt unit and near the contact area. And the belt means is held by the grounding means. The toner is transferred by the electrostatic force acting on the copy sheet by the charge held by the belt means, and the copy sheet is transferred from the electrostatic latent image carrier by the electrostatic force. An electrophotographic apparatus characterized by being separated. 2. 2. An electrophotographic apparatus according to claim 1, wherein said charge applying means is a corona discharger. 3. 2. The electrophotographic apparatus according to claim 1, wherein the resistance layer of the belt means is made of an elastic material, and the toner attached to the surface is removed by a cleaning blade. 4. 2. The electrophotographic apparatus according to claim 1, wherein the surface layer of the belt means is made of a material containing a fluorine resin.