JP2006259006A - Noncontact type charging roller, regenerating method for noncontact type charging roller, charging device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noncontact type charging roller capable of ensuring a charging gap with high accuracy and maintaining a satisfactory charging function for a long time, and to provide a regenerating method for the noncontact type charging roller. <P>SOLUTION: The conductive support 11 is formed from a stainless steel rod, the outside-diameter surface is hardened by baking, and variations in outside diameter of the surface is regulated by a centerless grinding process. A resistance adjustment layer 13 is formed on the surface of the conductive support 11. A protective layer 14 in which color is developed by the addition of a coloring agent is formed on the surface of the resistance adjustment layer 13 by spray coating. Further, the surface is polished with wrapping film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-contact charging roller that charges the surface of an image carrier in a non-contact manner, a method for reproducing (recycling) the same, a charging device including the non-contact charging roller, a copying machine including the charging device, a printer, The present invention relates to an image forming apparatus such as a facsimile or a plotter.

In a charging device used in an electrophotographic image forming apparatus such as a copying machine or a laser printer, charging is performed at a low voltage to suppress the generation of ozone and nitrogen oxide, the image forming apparatus is downsized, and the power source is low. For the purpose of cost reduction, a contact-type charging roller in which the outer diameter of the charging roller is made small and the charging potential application surface is in contact with the photosensitive member is often used.
The charging potential application surface of the contact-type charging roller is likely to become dirty due to adhesion of paper dust on the recording paper or toner remaining on the surface of the photosensitive member, and causes uneven charging. .
For this reason, non-contact type charging rollers that are less likely to become contaminated and have a relatively low maintenance frequency have been used.

However, the small-diameter non-contact type charging roller has a drawback that the rigidity is lowered because the metal shaft that is the conductive support in the central portion is also formed to be relatively thin. The variation in the charging gap formed by is likely to cause uneven charging by changing the charging potential to the photosensitive member.
For this reason, there is a tendency to increase the AC bias voltage to be superimposed on the DC voltage applied to the charging roller in order to prevent charging unevenness, the corona discharge becomes strong, and the charged potential application surface is easily damaged by the sputtering action.
Further, in the non-contact type charging roller, in order to achieve the low voltage charging equivalent to that of the contact type charging roller, the photosensitive member is charged by making the charging gap close to about 50 μm.

For this purpose, the dimensional accuracy of the members constituting the roller must be maintained with high accuracy, but it is difficult to ensure due to the reduction in rigidity, and problems such as narrowing of the charging gap are likely to occur. For this reason, it is not possible to maintain a constant charging gap reflecting the set gap, the toner remaining on the photoreceptor adheres to the charging potential application surface and is welded by strong corona discharge, and the discharge is not normally performed. The charged potential of the portion is changed, and the part is replaced before the lifetime of the part and the entire conductive support is discarded.
In view of such a situation, it has been proposed to regenerate and use the charged potential application surface for the purpose of protecting the global environment and reducing component costs.

For example, JP-A-8-171264 discloses a method for regenerating a charging member having at least two layers on a conductive support. This regeneration method is characterized by having a step of removing a surface layer to be a charged potential applying surface by mechanical polishing and a step of forming a layer on the polished surface.
Japanese Patent Laid-Open No. 8-137188 discloses a method in which a recovered charging roller is air blowed without removing a part of its surface, and a coating layer serving as a charged potential application surface is formed and regenerated. Yes.
Japanese Patent Application Laid-Open No. 2004-109688 discloses a method of reclaiming the recovered contact-type charging roller surface by washing with water and then heat-treating at 150 to 200 ° C.

JP-A-8-171264 JP-A-8-137188 JP 2004-109688 A

The method of regenerating the charging member varies depending on how it is used in the image forming apparatus, and a method peculiar to the charging member is required for efficient regeneration. In the mechanical polishing method described in Patent Document 1, since the conductive support is processed with a large amount of bending due to processing resistance, the center portion of the shaft is processed to be thick, and it is difficult to accurately process shaft runout. In the case of the contact type that does not require much, there is no problem, but it has not been possible to use it in the non-contact type that requires a highly accurate charging gap.
The method described in Patent Document 2 is to cover the resistance variation caused by toner or paper dust adhering to the surface of the charging roller with a coating layer, and the contact amount with a small use amount of about 3,000 to 3,000 images is formed. Although it can be used for a charging roller, a non-contact charging roller with a usage amount of 20,000 to 30,000 images tends to cause unevenness in resistance, and as a reproduction method, Absent.
The method described in Patent Document 3 is to remove a toner or paper powder adhering to the contact-type charging roller, and is used for a contact-type charging roller having a small number of image forming sheets of 2,000 to 3,000 sheets. However, it is not suitable as a regeneration method when the protective layer on the charged potential application surface is damaged by the sputtering action, such as a non-contact type charging roller having a usage amount of 20,000 to 30,000 images. Absent.

  The present invention can ensure a charging gap with high accuracy and maintain a good charging function for a long period of time, a regenerating method thereof, a charging device having the non-contact charging roller, and the charging device The main object is to provide an image forming apparatus having

  In order to achieve the above object, according to the first aspect of the present invention, in the non-contact charging roller formed by forming a resistance adjusting layer on the conductive support and forming a protective layer on the surface of the resistance adjusting layer, The conductive support is cured by quenching.

  According to a second aspect of the present invention, in the non-contact type charging roller according to the first aspect, the protective layer is formed of a material to which a colorant is added and can be distinguished from the resistance adjusting layer by visual observation.

  According to a third aspect of the present invention, in the method for regenerating a non-contact type charging roller, the protective layer of the non-contact type charging roller according to the second aspect is removed to form a resistance adjusting layer surface, and the resistance adjusting layer A protective layer is formed again on the surface of the film.

  According to a fourth aspect of the present invention, in the non-contact type charging roller, a thermoplastic support containing an ionic conductive polymer compound is coated on a conductive support that has been cured by quenching by injection molding to provide resistance. The adjustment layer is formed by forming a protective layer made of a thermoplastic resin composition in which conductive fine particles are dispersed on the surface of the resistance adjustment layer.

  According to a fifth aspect of the present invention, in the non-contact type charging roller according to the fourth aspect, the protective layer is removed by turning to form a resistance adjusting layer surface, and the protective layer is formed again and regenerated. It is characterized by.

  According to a sixth aspect of the present invention, in the non-contact type charging roller according to the fifth aspect, 1 to 5 W% of a colorant is added to the protective layer to develop a color.

  According to a seventh aspect of the present invention, in the non-contact charging roller according to the fifth aspect, the colorant added to the protective layer is an organic or inorganic pigment.

  In the invention according to claim 8, in the non-contact type charging roller according to claim 5, the cutting edge shape of the cutting tool used for turning is a nose R1-5 mm, a dent angle 5-10 °, a squeeze angle 10-20 °. The roughness of the blade surface is 0 to 0.2 [mu] m, and the cutting blade ridge formed by the blade surface is regenerated using a diamond bit with a radius of 0 to 2 [mu] m.

  According to a ninth aspect of the present invention, in the non-contact type charging roller according to the fifth aspect, the surface roughness of the resistance adjusting layer from which the protective layer is removed is 0.8 to 1.5 μm Rz (JIS B 0601 1994). ), And the outer diameter runout is formed in the range of 0 to 5 μm.

  According to a tenth aspect of the present invention, in the non-contact type charging roller according to the eighth aspect, a protective layer having a thickness of 5 to 10 μm is formed on the surface of the resistance adjusting layer by spray coating, and the outer diameter fluctuation is 0 to 0. It is formed in the range of 5 μm.

  According to an eleventh aspect of the present invention, in the non-contact type charging roller according to the ninth aspect, the protective layer that is formed again has a different color density as the amount of the colorant added is increased or decreased.

  According to a twelfth aspect of the present invention, in the non-contact charging roller according to the tenth aspect, the surface of the protective layer formed by spray coating is polished with a wrapping film, and the surface roughness is 0.5 to 1. It is characterized by being formed to 0.0 μm Rz (JIS B 0601 1994).

  According to a thirteenth aspect of the present invention, in the non-contact charging roller according to the fifth aspect, the conductive support is any one of SUS440A, SUS440B, SUS440C, and SUS440F described in a stainless steel rod (JIS G 4303 1998). And the outer diameter of the conductive support is hardened by induction hardening to a hardness HRC of 54 to 65 and a quenching depth of 0.8 to 2.5 mm. Is centerless ground so that the outer diameter runout is in the range of 0 to 5 μm.

  According to the fourteenth aspect of the present invention, a non-contact for applying a charging potential to the image carrier pair by forming a charging gap in a range that is in contact with both ends of the image carrier of the image forming apparatus and becomes a charging surface of the image carrier. A charging device having a charging roller, wherein the charging roller is a non-contact charging roller according to claim 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13. 3. A non-contact type charging roller regenerated by the method described in 3.

  According to a fifteenth aspect of the present invention, in the image forming apparatus having a charging device for charging the surface of the image carrier, the charging device is the charging device according to the fourteenth aspect.

According to the first aspect of the present invention, it is possible to suppress a decrease in rigidity due to a reduction in the diameter of the conductive support, and to reduce variations in the charging gap.
According to invention of Claim 2, the removal operation | work of a protective layer can be performed easily.
According to the third aspect of the present invention, regeneration by removing the protective layer can be performed easily and with high accuracy.
According to the fourth aspect of the present invention, it is possible to suppress a decrease in rigidity due to a reduction in the diameter of the conductive support and to reduce variations in the charging gap.

According to the fifth aspect of the present invention, even if the protective layer is formed again, the mechanical accuracy such as shaft runout is not deteriorated. Therefore, the superimposed AC bias voltage can be increased to correct the charging unevenness. Can be used without replay.
According to the sixth aspect of the present invention, the cutting resistance can be lowered, so that the shaft can be less bent, and the surface of the resistance adjustment layer can be formed and regenerated by removing the protective layer with high accuracy.

According to the seventh aspect of the present invention, it becomes a standard of the film thickness when removing the protective layer, and it can be reproduced with the turning allowance of the resistance adjusting layer being minimized.
According to the eighth aspect of the present invention, the turning allowance of the resistance adjusting layer is minimized without losing the color due to the decomposition by corona discharge and without losing the standard of the film thickness when removing the protective layer. Can be played.
According to the ninth aspect of the invention, it is possible to reproduce and use without increasing the superimposed AC bias voltage in order to correct charging unevenness.
According to the tenth aspect of the present invention, the film thickness can be formed without sagging or accumulation of the protective layer coating solution, and reproduction is performed without increasing the superimposed AC bias voltage to correct charging unevenness. Can be used.

According to the eleventh aspect of the present invention, it is possible to confirm the number of times of reproduction, and it is possible to prevent an excessive increase in the thickness of the resistance adjusting layer and an increase in the charging potential on the photosensitive member.
According to the twelfth aspect of the present invention, it is possible to suppress a minute abnormal discharge to the photosensitive member and roughness of the image to be formed.
According to the invention described in claim 13, the diameter of the central portion in the axial direction is small due to the bending of the conductive support when the protective layer is removed, and the turning allowance is reduced by turning without deteriorating the accuracy of the shaft runout. Reproduction can be performed with a small amount, and when the charging gap is formed, the gap is not narrowed and can be reproduced and used without increasing the superimposed AC bias voltage in order to correct charging unevenness.
Therefore, the generation amount of ozone and nitrogen oxide is not increased, and the image flow and the contamination of the indoor environment where the image forming apparatus is installed are not increased.
According to the invention described in claim 14, in the charging device, the effect described in claim 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 can be obtained.
According to the invention described in claim 15, in the image forming apparatus, the effect described in claim 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 can be obtained. . Moreover, component cost can be suppressed and the environmental load on component formation can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 16 (excluding FIG. 2).
First, the outline of the configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG. This image forming apparatus is a color image forming apparatus that uses a function-separated organic photoconductor and uses the Carlson process. The toner image forming unit 51 for each color of cyan, magenta, yellow, and black is moved in the moving direction of the transfer belt 58. Are arranged sequentially. In FIG. 15, reference numerals 60 and 61 denote paper feed cassettes, 62 denotes a registration roller pair, 63 denotes an ADF (automatic document feeder), and 64 denotes a manual feed tray.
The toner image forming unit 51 on the most downstream side in the moving direction of the transfer belt 58 will be described as a representative. As shown in FIG. 16, a cylindrical function-separated organic photoconductor 52 having an outer diameter of 30 mm to 100 mm is mainly used. A charging unit 53, an optical writing unit 54, a developing unit 55, and a cleaning unit 56 are disposed on the outer periphery.

The surface of the function-separated organic photoconductor 52 serving as an image carrier is charged with a positive or negative voltage of 600 to 800 V by the charging roller 59, and a latent image is formed by the laser beam 510. A visible image is formed by electrostatically attaching toner to the latent image by the developing member 511.
The toner image is electrostatically transferred onto the recording paper 512 by the transfer member 513, and the recording paper 512 on which the image has been transferred is conveyed to the fixing unit 514 and fixed by heating and pressing the toner image at about 160 to 200 ° C. .

In recent years, a method for charging a photoconductor of an image forming apparatus such as a copying machine or a laser printer has been proposed in order to reduce the size of the charging device and save space, and to reduce the amount of ozone generated when a charged potential is applied to the photoconductor. In addition, a proximity roller charging method that enables low voltage charging is employed.
In this proximity roller charging method, the roller surface layer is made of conductive rubber having a thickness of 1 to 2 mm in which a conductive agent such as carbon black is dispersed and mixed, and its resistance value is used to prevent charging unevenness during image formation. Is controlled to 10 ⁸ to 10 ⁹ Ωcm, and a contact-type charging roller that makes contact with the photoconductor without making a gap by using its elasticity is charged at a low voltage.
Alternatively, the surface of the conductive support is coated by 0.5 to 1 mm by injection molding with an ABS resin containing an ion conductive polymer compound such as polyether ester amide and having a resistance value controlled to 10 ⁸ to 10 ⁹ Ωcm. Then, a resistance adjusting layer is formed, and a protective layer made of a thermoplastic resin composition in which conductive fine particles such as tin oxide are dispersed is sequentially formed on the surface of the resistance adjusting layer, and gap holding members are used at both ends of the photoreceptor. A non-contact type charging roller that is brought into contact with each other and is brought into close contact with a gap of 30 to 100 μm so as not to come into contact with the photoreceptor is charged with a low voltage.

(Causes of damage to the charging potential application surface of the charging roller)
As shown in FIG. 10, in the non-contact type charging roller 211, a metal shaft member is used as a conductive support for applying a charging voltage. In this shaft member, a bearing portion 20, a voltage application bearing portion 21, and a covering portion 22 having an outer diameter of φ10 to 12 mm are integrally formed. On the peripheral surface of the covering portion 22, a polyether ester amide or the like is formed. A resistance adjustment layer 23 having a volume resistance value of 10 ⁸ to 10 ⁹ Ωcm of ABS resin, which is a thermoplastic resin containing an ion conductive polymer compound, is coated and molded to a thickness of 0.5 to 1 mm by injection molding.

On the surface of the resistance adjustment layer 23, there is a protective layer 24 having a volume resistance of 10 ¹¹ to 10 ¹² Ωcm made of a thermoplastic resin composition having a thickness of 0.3 to 0.6 μm and in which conductive fine particles of tin oxide are dispersed. Is formed.
In the non-contact type charging roller, the gap forming members 25 and 26 are covered to form a gap by making contact with both end portions of the photoreceptor, and a desired charging gap is formed.
The thickness of the gap forming members 25 and 26 is usually about 50 to 60 μm in order to reduce the applied voltage in order to suppress the amount of ozone generated. Teflon (registered trademark) tape or heat-shrinkable Teflon (registered trademark) is used. ) It is formed by coating a tube or the like.

As shown in FIG. 11, the non-contact type charging roller 211 shown in FIG. 10 is used to abut against both ends of the photosensitive member 212 of the image forming apparatus, and the charging gap 28 is placed in the range of the charging surface 27 of the photosensitive member 212. , 29, 210, the charging gap 29 in the central portion in the axial direction of the photosensitive member 212 tends to be narrow.
The charged potential changes at 5 to 10 V per 1 μm of the narrowing amount, and a defect that causes unevenness or roughness during image formation is likely to occur.
This is because the metal shaft member of the non-contact type charging roller 211 is reduced in size in order to reduce the size of the image forming apparatus and the mechanical strength in the axial direction is lowered. However, depending on the accuracy formed by the non-contact type charging roller 211 and the photosensitive member 212, the central portion in the axial direction is about 5 to 10 μm from the beginning with respect to the charging gap of 50 to 60 μm set in the central portion in the axial direction. There is a tendency that the charging gap 29 of the portion tends to become narrow.

Further, the axial runout of the covering portion 22 of the metal shaft member is likely to occur at 10 to 20 μm at the central portion in the axial direction of the non-contact type charging roller 211. If the non-contact type charging roller 211 is formed as it is, the charging gap with the photoconductor 212 is increased. Becomes narrower with rotation.
If the charging gap is set to 50 μm, the charging gap 29 at the central portion in the axial direction is about 20 to 35 μm at the time of the minimum narrowness, and contacts with the remaining toner and adheres to the central portion of the non-contact type charging roller 211 and is contaminated. The adhering toner is fused by corona discharge.
The width of the charging gap 29 in the central portion has a large influence on the formation of the charging gap if the mechanical strength in the axial direction of the metal shaft member is lowered, and the AC bias voltage is superimposed to prevent charging unevenness. The surface of the charging roller is damaged by corona discharge by raising (Vp-p).

In the non-contact type charging roller, when correcting the charging unevenness without correcting the shape and accuracy in the linearity of the shaft, the AC bias voltage (Vp superimposed) to correct the charging unevenness is corrected. -P) is about -2000 to -2400V for -800V charging, and the surface of the charging roller is discharged at a high voltage.
As a result, the degree of decomposition and wear of the resin component that becomes the binder of the protective layer on the outermost surface is increased due to the sputtering action of ions and electrons generated, and the roughness of the formed image is generated. It is forced to exchange.
In addition, the degree to which the surface of the organic photoreceptor is damaged by collision of generated ions and electrons is increased, and the lifetime is shortened due to decomposition and wear of the resin forming the photosensitive layer. In addition, since the discharge is performed at a high voltage, the amount of ozone and nitrogen oxide generated increases, and the indoor environment where the image forming apparatus is installed is contaminated with odors.

(Configuration and Regenerating Method of Non-Contact Charging Roller of the Present Invention)
Therefore, in the present embodiment, in order to accurately form the axial runout of the surface to which the charging potential of the non-contact type charging roller is applied, first, the conductive support is made of a stainless steel rod, as described in (JIS G 4303 1998). Any one of SUS440A, SUS440B, SUS440C, and SUS440F is used, the outer diameter is φ10 to 12 mm, the outer diameter surface of the conductive support is cured by quenching, and the hardness is in the range of HRC54 to 65 The surface formed on the surface is formed with an outer diameter runout of 0 to 5 μm by centerless grinding.
The surface of the formed conductive support is coated with an ABS resin containing an ion conductive polymer compound containing an ion conductive polyether ester amide component with a thickness of 0.5 to 1 mm by injection molding, and turning. By processing, the surface roughness is 0.8 to 1.5 μm Rz (JIS B 0601 1994) and the outer diameter runout is 0 to 5 μm to form a resistance adjustment layer.

On the surface of the resistance adjusting layer, there is provided a protective layer made of a thermoplastic resin composition in which conductive fine particles of a curing agent and tin oxide are dispersed in a ceramic resin containing a fluororesin component and a polysiloxane component in an acrylic or polyurethane skeleton. The film is sequentially formed by spray coating at a thickness of 10 μm, and the surface is further polished with a wrapping film to adjust the surface roughness to 0.5 to 1.0 μm Rz (JIS B 0601 1994).
Even in this non-contact type charging roller, the thermoplastic resin composition on the outermost surface of the protective layer is damaged by corona discharge over time, roughening the surface roughness and causing roughness in image formation. Also, when a large amount of the same image is taken, reproduction is necessary because the toner is fused to the outermost surface of the protective layer corresponding to the toner image forming portion.

(Bending amount of metal shaft member that is a conductive support)
A thin line in the graph of FIG. 12 is a graph obtained by measuring the amount of deflection of a metal shaft member of a commonly used non-contact type charging roller. The shaft member made of SUS having an outer diameter of 8 to 12 mm and a length of 340 mm. When the center part of the material is pressed at 0.5 to 3N, a deflection of 5 to 80 μm occurs.
The amount of this bending is larger in the shaft member 30 of φ8 mm than the shaft member 31 of φ10 mm and the shaft member 32 of φ12 mm, and when used at a length of 340 mm as the shaft member used in the image forming apparatus, the mechanical strength is increased. It is difficult to process, and the central part escapes, and it is assumed that the diameter is increased or the shaft is swung. This causes a narrowing of the charging gap.

Actually, a SUS shaft member having a diameter of 8 mm and a length of 340 mm, in which the charging roller is formed, has an axial diameter increase of 10 to 15 μm and an axial runout of 15 to 20 μm. In addition, the charging gap cannot be maintained, and problems such as toner adhering to the narrowed portion occur.
In order to prevent charging unevenness, the superimposed AC bias voltage (Vp-p) must be raised to -2000 to -2400 V, and strong discharge is performed to roughen the surface roughness of the protective layer of the charging roller. As a result, roughness in the image formed by the image forming apparatus has occurred, causing problems such as damage to the surface of the organic photoreceptor.
For this reason, the use of a shaft member having a diameter of 10 to 12 mm facilitates ensuring the mechanical accuracy of the charging roller and improves the productivity.

In the graph of FIG. 12, the thick line indicates that the material of the metal shaft member is a martensitic SUS shaft member (described in JIS Handbook 1999 Iron and Steel I), which is described in JIS G 4303 (1998) stainless steel rod. A material of SUS440 (SUS440A, SUS440B, SUS440C, SUS440F) is used, and an outer diameter of φ8-12 mm is subjected to induction hardening with a quenching depth of 0.8-2.5 mm, and its hardness is HRC54-65. The amount of bending of the metal shaft member is measured.
The φ8 SUS440 hardened material 33 has a bending amount of 10 to 20 μm lower than that of the φ8 SUS material 30, but it can be seen that the bending amount is also large and inconvenient as a metal shaft member of the charging roller. .

The φ10 SUS440 hardened material 34 has a 5 to 10 μm bending amount lower than that of the φ10 SUS material 31. Similarly, the φ12 SUS440 hardened material 35 is 3 to 3 times smaller than the φ12 SUS material 32. It can be seen that the amount of deflection of 7 μm decreased and the shaft strength increased.
In this way, the outer diameter surface is induction hardened with a quenching depth of 0.8 to 2.5 mm, and the hardness of any of SUS440A, SUS440B, SUS440C, and SUS440F described in a stainless steel rod (JIS G 4303 1998) is HRC54. If a charging roller is formed using a metal shaft member that has been cured to ˜65 and has increased shaft strength, the increase in strength does not deteriorate the accuracy during machining and ensures a set charging gap. It is easy to rotate, and even when the protective layer is turned, there is little bending and the turning allowance can be minimized, so that it is possible to regenerate multiple times.

(Regeneration processing of protective layer of non-contact charging roller)
FIG. 1 shows a layer structure of a reproducible non-contact charging roller 123A in the present embodiment. The overall configuration is the same as that shown in FIG.
The non-contact type charging roller 123A has a hardened hardening layer 12 in which a hardening treatment with a hardening depth of 0.8 to 2.5 mm is performed on the surface of the metal shaft member 11 as a conductive support by induction hardening. The outer diameter runout is 0 to 5 μm by the less grinding process, and the resistance adjusting layer 13 and the protective layer 14 are formed thereon.
The protective layer 14 has a thickness of 5 to 10 μm, and is colored by adding 1 to 5 W% of an organic or inorganic pigment as a colorant.
In the conventional non-contact type charging roller, as shown in FIG. 2, a metal shaft member 15 that is not subjected to curing treatment is used, and the resistance adjusting layer 16 contains an ion conductive polymer compound such as polyether ester amide. A thermoplastic resin such as ABS resin is coated by injection molding to give a milky white color.
Further, the protective layer 17 contains 50 to 70 W% of white stannic oxide as conductive fine particles dispersed in a translucent thermoplastic resin composition such as a fluororesin or a urethane resin, and also exhibits a milky white color. Therefore, the boundary between the resistance adjustment layer 16 and the protective layer 17 is not clear enough to be visually confirmed. For this reason, when it is going to remove the protective layer 17 completely, it will process by a large turning allowance.

However, as shown in FIG. 11, the gear 213 of the non-contact type charging roller 211 and the gear 214 of the photosensitive member 212 are meshed to transmit rotation, and further, the gear shaft distance 215 is ensured to ensure a charging gap. Is increased by 0.1 to 0.2 mm, and the gears are meshed with backlash. Therefore, if the turning allowance is increased, the gear center distance 215 is reduced and the backlash is eliminated. Since the gear side is lifted and a charging gap cannot be secured, it is impossible to take a large amount of turning allowance.
The thickness of the resistance adjustment layer 13 is 0.5 to 1 mm. However, removing 50 μm or more also increases the charging potential of the photosensitive member. Similarly, a turning allowance is used to remove the protective layer 14. Can't take much.

Therefore, in order to minimize the turning allowance, the protective layer 14 is colored by adding 1 to 5 W% of an organic or inorganic pigment as a colorant, and the removal state is easily confirmed by visual inspection in the turning process. It can be so. Further, in the process of producing a large number, the outer diameter of the resistance adjusting layer 13 is defined and the dimensional tolerance is narrowed.
Usually, when the outer diameter of the protective layer 14 is φ12 mm, the outer diameter of the metal shaft member 11 is φ10 mm, the thickness of the resistance adjustment layer 13 is about 1 mm, and the outer diameter is φ11.9 ± 0.1 m. However, the outer diameter is suppressed to about φ11.9 ± 0.01m, the accuracy is kept high, the protective layer 14 is formed to 5 to 10 μm, and the conditions that can be easily regenerated at the time of reprocessing are incorporated. deep.
Furthermore, what is required at this time is the accuracy of the shaft runout of the metal shaft member 11, and in order to improve the accuracy, hardening treatment by quenching is performed, and the mechanical strength of the metal shaft member 11 can be increased and regenerated. Create the appropriate conditions.

  The metal shaft member 11 is any one of SUS440A, SUS440B, SUS440C, and SUS440F described in a stainless steel rod (JIS G 4303 1998), and has an outer diameter of φ10 to 12 mm. The outer diameter surface of 11 is hardened by a high-frequency quenching depth of 0.8 to 2.5 mm, the hardness is in the range of HRC 54 to 65, and the surface of the outer diameter surface of the metal shaft member 11 is removed by centerless grinding. The diameter runout is set to 0 to 5 μm, the outer diameter is held, the bearing portion 20 and the voltage application bearing portion 21 are turned, and the coaxiality is set to 0 to 5 μm so that the condition can be further regenerated. Can do.

FIG. 3 shows a non-contact condition in which a resistance adjusting layer 13 and a protective layer 14 are formed on a metal shaft member 11 whose shaft runout has become highly accurate due to quenching and centerless grinding, and has a reproducible condition. A method for turning the protective layer 14 of the charging roller is shown, and a cutting tool for cutting uses a diamond cutting tool capable of forming a sharp edge in order to keep cutting resistance low.
Using a straight-sword diamond tool, the cutting edge has a nose radius of 1 to 5 mm, a dent angle of 5 to 10 °, a squeeze angle of 10 to 20 °, and a roughness of the blade surface of 0 to 0.2 μm. A cutting tool 18 having a round radius of 0 to 2 μm is used.
Using this cutting tool 18, a bearing for applying voltage to a non-contact type charging roller by a spindle chuck 19 (air balloon chuck manufactured by Fujii Seimitsu Kogyo Co., Ltd.) of a synchronous rotary type turning apparatus (RL600 model manufactured by Egro Co., Ltd.) The outer diameter of 21 is clamped, the outer diameter of the bearing portion 20 is clamped by a tail shaft chuck 110 (air balloon chuck manufactured by Fujii Seimitsu Kogyo Co., Ltd.), the synchronous rotation drive of 5000 to 6000 rpm is applied to the main shaft and the tail shaft, and the protective layer 14 Rotating feed 0.1mm / rev, cutting depth 5-10μm, moving the tool post 111 with the cutting tool 18 mounted, roughing, finishing with the same cutting depth 3-5μm, and coloring coloring The surface of the resistance adjusting layer 13 regenerated by removing the layer 14 and its roughness 0.8 to 1.5 μm Rz (JIS B 0601 1994) are obtained. .

The resistance adjustment layer 13 under the protective layer 14 is molded using an ABS resin containing an ion conductive polymer compound such as polyether ester amide and is milky white. Therefore, the protective layer 14 colored with a colorant is formed. If it remains, the processing residue can be easily confirmed.
For this reason, it is easy to determine whether processing is possible, and processing can be performed with a minimum processing cost.
As shown in FIG. 4, the turning process is performed by blowing compressed air from the air nozzle 112 to the tip of the blade 113 in order to suppress heat generation and guide chips to the suction device.
The cutting tool 113 for turning is attached with the squeeze surface 114 facing downward and suctioning chips with the lower hood 115 to prevent the chips from adhering to and getting caught on the surface of the workpiece. A chip suction speed corresponding to the cutting speed is secured and the chip is sucked by the chip collecting device 116, and the chip is stored in a box 117, compressed and collected.

Processing of the resistance adjustment layer 13 using an ABS resin containing an ion conductive polymer compound such as polyether ester amide can be performed at a high processing speed by using a turning process using a diamond blade 18. Further, by sharpening the shape of the cutting edge of the cutting tool 18, it becomes possible to suppress the processing resistance as compared with grinding, and it is possible to suppress the increase in the outer diameter of the central portion in the axial direction of the non-contact type charging roller.
In addition, since the heat generation is less than that of the grinding method, it is possible to perform processing that does not require a cutting fluid, and is a method suitable for regenerating the resistance adjustment layer 13 that easily absorbs moisture and easily changes its electric resistance.

FIG. 5 shows a method of forming the protective layer 14 again by spray coating on the surface of the resistance adjusting layer 13 from which the protective layer 14 has been removed.
Masking jigs 118 and 119 for forming a moisture absorption preventing shape of the resistance adjustment layer 13 are attached to the outer diameters of the voltage application bearing portion 21 and the bearing portion 20 of the non-contact type charging roller and clamped, and the main shaft 120 has a speed of 100 to 300 rpm. Give rotational drive.
Thermoplastic resin composition in which a resin composition containing a fluororesin component, a polysiloxane component and ceramics and a curing agent and conductive fine particles of tin oxide of 0.3 to 0.6 μm are dispersed in a polyurethane or acrylic skeleton from a spray nozzle 121. The protective layer solution to which 1 to 5 W% of phthalocyanine blue was added as a product and a coloring pigment was sprayed to a film thickness of 5 to 10 μm by baking at 100 to 130 ° C. for 30 minutes, as shown in FIG. The reproduction protective layer 122 that is colored is formed.
The regeneration protection layer 122 increases or decreases the amount of the colorant added to have a different color density so that the regeneration use limit can be determined by confirming the number of regenerations.

In FIG. 7, the surface of the non-contact type charging roller 123B on which the regeneration protection layer 122 is formed is polished with a wrapping film tape 124 having a particle size of 3000 to 8000, and a protrusion 125 (dendritic shape is present by spray coating). 8) and a reproduction protective layer surface 126 (see FIG. 9) having a surface roughness adjusted to 0.5 to 1.0 μm Rz (JIS B 0601 1994), thereby forming an image caused by charging. It is possible to obtain a stable surface that hardly causes roughness and abnormal discharge.
Thereafter, the charging gap forming members 25 and 26 are covered at both ends to complete a non-contact type charging roller having a reproduction protective layer.

Next, a comparative experiment result of the charging potential on the photosensitive member between the protective layer recycled product non-contact type charging roller and the new protective layer non-contact type charging roller will be described. FIG. 13 is a configuration diagram of the charged potential measuring apparatus.
The non-contact type charging roller 40 in the present embodiment is arranged with a charging gap of 50 μm, a function-separated organic photoconductor 41 is used as a member to be charged, and its layer structure is a substrate (aluminum φ30 mm), an undercoat layer of 5 μm. (Melamine alkyd resin, oxidized Ti dispersion), charge generation layer 0.5 μm (titanyl phthalocyanine + butyral resin), charge transport layer 30 μm (polycarbonate resin, charge generator stilbene series).
The equipment used for the measurement is a high-voltage power supply 42 (FLUKE 415B 0 to ± 3 KV), a surface potential meter 43 (TREK 344), a surface potential meter probe 44 (measurement interval about 1 mm), and a recorder 45 (GRAPHTEC SERVO 150).
The function-separated organic photoconductor 41 is rotated at a linear speed of 235 mm per second, and the charged potential on the surface is removed by using a conductive static elimination brush 46.

FIG. 14 is a measurement chart comparing the charge potentials on the function-separated organic photoconductor 41 between the protective layer recycled product non-contact type charging roller and the new protective layer non-contact type charging roller. The applied voltage value 47 of the new protective layer non-contact type charging roller required for the surface potential of −800 V to the function-separated organic photoconductor 41 is DC-1640 V, and the applied voltage value 48 of the non-contact type charging roller of the protective layer recycled product. Is DC-1650VV.
DC-1650V was continuously applied for 2.5 minutes to the protective layer recycled product non-contact type charging roller, and the change in the charging potential 49 to the function-separated organic photoconductor 41 was confirmed. stable.
Further, the charged potential 410 applied to the function-separated organic photoconductor 41 when applied for 4.5 minutes continuously is stable without fluctuation, and it is possible to remove the protective layer and use it without any problem in terms of charging characteristics. I know that there is.
Table 1 shows comparison data between a non-contact type charging roller (recycled product of a protective layer) (Example), a new non-contact type charging roller (Comparative Example) and a conventional product.

  As shown in Examples 1 and 2 in Table 1, the AC bias voltage (Vp-p) that is superimposed to prevent charging unevenness within the image unevenness limit, It is in the range of -1600 to 1800V with respect to the charged potential of -800V of the function-separated organic photoconductor, and is in the same range as the new protective layer of the comparative example. do not do.

  The charging device incorporating the non-contact type charging roller in which the protective layer of the present invention is regenerated, particularly applies an AC bias voltage (Vp-p) to give a desired charging potential to the photoreceptor and prevent charging unevenness. If the charging device can be applied with a charging potential without increasing it, and there is no occurrence of roughness in image formation, and the charging device of an image forming apparatus that forms black and white and color images, the component cost is reduced. In addition, the energy for processing and forming can be reduced, so that it is possible to cope with the environment.

  Applicability of the present invention includes a method for reproducing an image electrostatic transfer roller.

It is sectional drawing of the non-contact-type charging roller which can be recycled in this invention. It is sectional drawing of the conventional non-contact-type charging roller which can be reproduced | regenerated. It is a figure which shows the turning method of the protective layer of the non-contact-type charging roller which can be recycled in this invention. It is a figure which shows the chip | tip collection | recovery apparatus in turning. It is a figure which shows the method of spray-applying a protective layer again on the surface of a resistance adjustment layer. It is sectional drawing of the non-contact-type charging roller which has a reproduction | regeneration protection layer. It is a figure which shows the method of grind | polishing the surface of the non-contact-type charging roller with which the protective layer was reproduced | regenerated. It is a figure which shows the surface property before grinding | polishing of a protective layer. It is a figure which shows the surface property after grinding | polishing of a protective layer. It is a figure which shows the basic composition of a non-contact-type charging roller. It is a figure which shows the positional relationship of a non-contact-type charging roller and a photoreceptor. It is a graph which shows the comparison of the deflection amount of the shaft member of a non-contact-type charging roller. It is a block diagram of a charging potential measuring device. It is a comparison chart of charging potential. 1 is a schematic configuration diagram of an image forming apparatus. FIG. 3 is an enlarged view of one toner image forming unit in the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Metal shaft member as an electroconductive support body 13 Resistance adjustment layer 14 Protection layer before reproduction | regeneration 53 Charging unit as a charging device 18 Cutting tool 122 Protection layer after reproduction | regeneration 123A, 123B Non-contact-type charging roller 124 Wrapping film

Claims (15)

In a non-contact type charging roller in which a resistance adjusting layer is formed on a conductive support and a protective layer is formed on the surface of the resistance adjusting layer.
A non-contact charging roller, wherein the conductive support is cured by quenching. The non-contact charging roller according to claim 1,
The non-contact type charging roller, wherein the protective layer is formed of a material to which a colorant is added, and can be distinguished from the resistance adjusting layer by visual observation.   The non-contact type charging roller according to claim 2, wherein the protective layer is removed to form a resistance adjusting layer surface, and the protective layer is formed again on the surface of the resistance adjusting layer. How to play.   On a conductive support cured by quenching, a thermoplastic resin containing an ionic conductive polymer compound is coated by injection molding to form a resistance adjusting layer, and conductive fine particles are dispersed on the surface of the resistance adjusting layer. Non-contact charging roller formed by forming a protective layer made of the thermoplastic resin composition. The non-contact charging roller according to claim 4,
A non-contact charging roller, wherein the protective layer is removed by turning to form a resistance adjusting layer surface, and the protective layer is formed again and regenerated. In the non-contact charging roller according to claim 5,
A non-contact type charging roller characterized in that a colorant is added to the protective layer in an amount of 1 to 5 W% to develop a color. In the non-contact charging roller according to claim 5,
A non-contact charging roller, wherein the colorant added to the protective layer is an organic or inorganic pigment. In the non-contact charging roller according to claim 5,
The cutting edge shape of the cutting tool used for turning is a nose R 1 to 5 mm, a dent angle 5 to 10 °, a squeeze angle 10 to 20 °, and the roughness of the blade surface is 0 to 0.2 μm. A non-contact type charging roller which is regenerated using a diamond cutting tool having a round radius of 0 to 2 μm. In the non-contact charging roller according to claim 5,
The resistance adjustment layer from which the protective layer has been removed has a surface roughness of 0.8 to 1.5 μm Rz (JIS B 0601 1994) and an outer diameter runout of 0 to 5 μm. Contact charging roller. The non-contact charging roller according to claim 8,
A non-contact type charging roller, wherein a protective layer having a thickness of 5 to 10 [mu] m is formed on the surface of the resistance adjusting layer by spray coating, and an outer diameter fluctuation is in a range of 0 to 5 [mu] m. The non-contact charging roller according to claim 9,
The non-contact type charging roller, wherein the protective layer formed again has a different color density as the amount of colorant added is increased or decreased. The non-contact charging roller according to claim 10,
The surface of the protective layer formed by spray coating is polished by a wrapping film and has a surface roughness of 0.5 to 1.0 μm Rz (JIS B 0601 1994). roller. In the non-contact charging roller according to claim 5,
The conductive support is any one of SUS440A, SUS440B, SUS440C, and SUS440F described in a stainless steel rod (JIS G 4303 1998), and has an outer diameter of φ10 to 12 mm. The diameter surface is hardened by induction hardening to a hardness HRC of 54 to 65 and a quenching depth of 0.8 to 2.5 mm, the outer diameter surface is centerless ground, and the outer diameter runout is in the range of 0 to 5 μm. Non-contact charging roller characterized by In a charging device having a non-contact type charging roller that is in contact with both end portions of an image carrier of an image forming apparatus and forms a charging gap in a range that becomes a charging surface of the image carrier to apply a charging potential to an image carrier pair.
The said charging roller was regenerated by the non-contact type charging roller according to claim 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or the method according to claim 3. A charging device which is a non-contact charging roller. In an image forming apparatus having a charging device for charging the surface of an image carrier,
An image forming apparatus, wherein the charging device is the charging device according to claim 14.

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