JPH11109746A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a developing device capable of prolonging the life of a developing sleeve by forming a part abutted on the sleeve, of metal constituted so that the difference between the coefficients of linear expansion of the metal and the sleeve is <= a specific value and making thermal conductivity higher than that of the metal of which a part not abutted on the sleeve is formed. SOLUTION: The developing device 2 has the developing sleeve 2a, the surface of the developing device 2 is coated with a resin layer including conductive grains, etc., and a flange for supporting the developing sleeve 2a consists of two or more kinds of metallic members. Then, the part abutted on the sleeve of the flange, out of the part constituting the flange is formed of the metal constituted so that the difference between the coefficients of linear expansion of the metal and the sleeve is <= 5 (K<1> ) and the thermal conductivity is higher than that of the metal of which the part not abutted on the sleeve, of the flange is formed. By such a constitution, a high-quality image not having a hot image and an irregularity in the pitch of the sleeve can be provided, the resistance to wear of the flange is improved and the developing device whose life is prolonged can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for forming a latent image on an electrostatic latent image carrier by an electrophotographic method or the like to visualize the electrostatic latent image. Related to developing devices such as printers and copiers.

[0002]

2. Description of the Related Art Conventionally, a developer has a charging means for uniformly charging an electrostatic latent image carrier, an exposure means for forming an electrostatic latent image, and a developing means for visualizing the electrostatic latent image. 2. Description of the Related Art An image forming apparatus is known in which an image is transferred to a transfer material by a transfer device, and a residual developer on the electrostatic latent image carrier is removed by a cleaning device. This will be described with reference to FIG. The image forming apparatus has, for example, a photosensitive drum 1 as an electrostatic latent image carrier. The photosensitive drum 1 has a photoconductive layer such as OPC or a-Si on its surface and is rotated clockwise. The surface of the photosensitive drum 1 is uniformly charged to, for example, −500 V by the primary charger 3. Next, an image exposure 12 is performed to form an electrostatic latent image on the photosensitive drum 1. As the image exposure 12, for example, analog exposure, a semiconductor laser, or an LED array is used. Next, regular development or reversal development is performed by the developing device 2 to visualize it as a toner image. Thereafter, the toner image is transferred by the transfer charger 4 to the transfer material that advances in the direction of the arrow, and is sent to the fixing device 7 to fix the toner image to obtain a fixed image. In recent years, digitalization has progressed, and higher image quality and higher durability have been demanded. Therefore, for the purpose of eliminating a ghost image generated at the sleeve cycle also as a developing device, a film mainly made of resin is formed on the sleeve of the developer carrier,
Prevents charging of developer tribo.

[0003] A developing device that visualizes an electrostatic latent image formed on an electrostatic latent image carrier using a developing device in which the surface of the developer carrier is coated as described above is known. .

[0004]

However, the above conventional example has the following problems.

When both the developing sleeve and the flange are made of SUS, the cost is increased due to the material cost. When a-Si is used as a photosensitive member in a high-speed machine, a heater is inserted inside the a-Si drum as a measure against image flow in a high temperature / high humidity (30 ° C./80%) environment. The surface is heated to around 40 ° C, while the opposite surface is at room temperature 25 ° C due to poor heat conduction of SUS
Therefore, the SUS sleeve is eccentric due to heat, and as a result, an image of uneven sleeve pitch is generated.

Further, both the developing sleeve and the flange are made of Al.
In this case, there is no unevenness of the sleeve pitch because there is almost no eccentricity due to heat because of good heat conduction. However, if the flange is made of Al, the abrasion resistance of the shaft is poor and the life of the developing carrier is not one million sheets. The shaft of the flange shortened the life of the developer carrier. Further, in a sleeve driving portion (sleeve flange shaft portion) or a gap holding portion between the sleeve and the photosensitive member, which is connected by a high-speed motor, when the temperature rise of the flange shaft portion caused by the high-speed rotation is transmitted to the image area portion of the sleeve, the toner characteristic is reduced. Deterioration due to heat was promoted, which appeared as a decrease in image density.

When a film is heated to 100 ° C. or higher to form a film on the surface of the developer carrying member, and the material of the dried flange is different from the material of the flange (for example, SUS and Al), the sleeve is not heated when heated. Since the linear expansion coefficients of the two at the joint of the flange are different, a gap is created even when joined by adhesive, caulking, press-fitting, etc. After cooling, a gap is created and the joining force is weakened, and the standard torque value becomes 200 kgf. On the other hand, when the developing device is rotated, the flange and the sleeve come off, and the image is not displayed.

Further, even if the developing sleeve is made of Al and the flange is made of SUS, the fitting of the joint is made negative and the screw is forcibly screwed in, the torque of the sleeve and the flange after the heating of the developer carrier is inevitably reduced. In addition, when a developing bias is applied to the developer carrying member in order to form an image by swelling both end portions (joining portions) of the sleeve, the gap between the drum and the developer carrying member becomes small at both ends, thereby causing leakage. Had occurred.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a charging device for uniformly charging an electrostatic latent image carrier, an exposure device for forming an electrostatic latent image, and a developing device for visualizing the electrostatic latent image. Achieves high-quality images without sleeve pitch unevenness, satisfies the required torque when rotating the developer carrier, improves the abrasion resistance of the flange, and prevents the temperature rise in the image area of the sleeve to maintain the density. It is an object of the present invention to provide a developing device which can be used and has a long life of a developer carrying member.

[0010]

SUMMARY OF THE INVENTION The present invention provides a charging means for uniformly charging an electrostatic latent image carrier, an exposure means for forming an electrostatic latent image, and a developing means for visualizing the electrostatic latent image. In the apparatus, the developing device has a magnet roll composed of a plurality of magnetic poles and a developer carrier composed of a non-magnetic sleeve that covers the outer periphery thereof, and a resin layer containing conductive particles or metal on the surface of the developer carrier. The flange that coats the plating layer and supports the developer carrier is made of two or more types of metal members. Of the parts that make up the flange, the part that contacts the sleeve of the flange is the linear expansion coefficient. difference constitutes from 5 (K ^-1) or less of the metal, and relates to a developing apparatus wherein the thermal conductivity is greater than the metal constituting the portion that does not contact the sleeve of the flange.

According to the present invention having the above-described structure, it is possible to realize a high-quality image without ghost images or sleeve pitch unevenness, satisfy the required torque when the developer carrier is rotated, and improve the abrasion resistance of the flange to improve the developer. A developing device having a long life of the carrier can be provided.

Further, in a sleeve driving portion (sleeve flange shaft portion) connected by a high-speed motor or a gap holding portion between the sleeve and the photosensitive member, a temperature rise of the flange shaft portion caused by high-speed rotation is transmitted to the image area portion of the sleeve. And a developing device capable of maintaining the density by preventing the temperature of the image portion of the sleeve from rising.

When the flange is made of three or more kinds of metal, the linear expansion coefficient is reduced in the order of increasing the distance from the sleeve, so that the joint between the sleeve and the flange is further strengthened. It is possible to provide a developing device in which the torque during rotation of the agent carrier is maintained and there is no rotation unevenness.

The conductive resin layer formed on the surface of the developer carrying member is characterized in that the resin layer is made of an epoxy resin or a phenol resin and contains TiO ₂ or crystalline graphite. A developing device can be provided.

The method of bonding the metal constituting the flange for supporting the developer carrying member is welding, or after forming a metal shaft, another metal is poured into a mold and cooled to perform die casting. Accordingly, it is possible to provide a developing device in which the joining between the sleeve and the flange is further strengthened, the torque during the rotation of the developer carrier is maintained, and the rotation is not uneven.

Further, since the method of bonding the metal forming the flange supporting the developer carrying member is knurling, the joining between the sleeve and the flange is further strengthened, and the torque during rotation of the developer carrying member is maintained. It is possible to provide a low-cost developing device while preventing rotation unevenness.

Further, the metal constituting the flange for supporting the developer carrying member is different in the kind of metal at the joint portion between the shaft portion of the developer carrying member and the sleeve, so that the joint between the sleeve and the flange is further strengthened. In addition, it is possible to provide a low-cost and simple developing device while maintaining torque during rotation of the developer carrying member so as to prevent rotation unevenness.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] In this embodiment, a digital copying machine using an a-Si drum as a photosensitive member in the image forming system shown in FIG. 7 will be described. The surface of the photosensitive drum 1 is uniformly charged to +500 V by the primary charger 3. Next, PWM at 600 dpi with a semiconductor laser having a wavelength of 680 μm.
To form an electrostatic latent image on the photosensitive drum 1. Next, the image is reversely developed by the developing device 2 and is visualized as a toner image. The developer performs jumping development using a positive magnetic one-component toner. The developing bias is 200
A bias voltage obtained by superimposing a DC voltage of +400 V on an AC voltage of 0 Hz, 1500 Vpp, and 50% duty is applied. S-Bgap is 250 μm, S-Dgap is 250 μm
μm. After that, total current + 200μ with post charger
After the flow A, the toner image is charged, the toner image is transferred to the transfer material advancing in the direction of the arrow by the transfer charger 4 and sent to the fixing device 7 to fix the toner image. The developing device 2 has a configuration shown in FIG.
Now, the developing sleeve will be described.

As shown in FIG. 8, the developing sleeve uses 20 mm Al as a sleeve tube, has a wall thickness of 0.8 mm, and has a thermosetting epoxy resin, TiO ₂ and carbon on its surface in a ratio of 100: 40. : A film mixed at a ratio of 3 is prepared. The structure of the film is based on sleeve ghost, charge imparting property to toner, durability, and film uniformity (dispersibility of conductive material).
The ratio between the resin B and the conductive member (carbon, TiO ₂ , graphite, etc.) P is preferably P / B = 1 / 1.0 to 3.0.
The film thickness is preferably 5 to 20 μm for the above items. This is to eliminate charge-up of toner charge in order to reduce sleeve ghost. After the above-mentioned film is applied to the developing sleeve, the film is dried by heating at 170 ° C. for 40 minutes using a dryer. After forming a film on the sleeve tube, a method of attaching a magnet roll and attaching a flange is also conceivable, but it is very difficult to suppress the runout of the sleeve to 20 μm, so a method of coating the assembled sleeve is used. Take. When high image quality is assumed in a digital image forming apparatus as in the present case, the above-mentioned coat is indispensable in order to prevent a ghost image due to the sleeve.

Further, since the high-speed machine uses a highly durable a-Si photosensitive drum and is equipped with a drum heater to prevent image flow in a high humidity environment, the drum-facing surface of the developing sleeve is thermally expanded. The deflection of the sleeve became large, and as a result, the sleeve pitch became uneven in the halftone image. This is particularly bad for SUS sleeves with poor heat conduction. On the other hand, Al with good heat conductivity is greatly reduced. However, when the Al sleeve blank is used with the flange being the conventional SUS, even if a strong adhesive is used at the joint between the sleeve and the flange when heat is applied in the drying step in producing the coat, Table 1 Al of the sleeve as shown in
The coefficient of linear expansion between SUS and the flange is different from that of SUS, Al expands easily, SUS hardly expands, a gap is formed, the strength of the joint decreases, and the rotation torque is low due to durability in the image forming apparatus. And the flange had come off. Also, if the fitting of the flange and the sleeve is mechanically negative and the SUS flange is forcibly screwed into the Al tube, the sleeve tube at the screwed position will bulge and both ends of the sleeve will bulge. A leak image occurs due to the approaching distance. On the other hand, if the flange is made of Al, the shaft portion will be shaved due to friction at the bearing portion supporting the shaft during durability, and the bearing will not be able to be taken out at the time of periodic replacement of the sleeve, making it impossible to replace it.

Table 2 summarizes the above and shows a comparison between the configurations.

[0022]

[Table 1]

[0023]

[Table 2]

Therefore, in this embodiment, the sleeve blank (2A-
0) using A6063 of Al, and the flange is shown in FIG.
As shown in (a) and (b), the flange shaft (2A-2) is SU
After forming a SUS shaft, the SUS shaft was put into a flange mold, and the 2A-1 portion was die-cast in A201.
7 and metal bonding. In this way, by using a metal having the same or similar (thermal linear expansion coefficient) as that of the sleeve tube, the torque of the joint due to the difference in thermal expansion does not decrease even after heating (170 ° C.) during coating drying. (Because Al has a higher linear expansion coefficient in the SUS flange than the Al sleeve, a gap is created during heating and the torque is reduced; see the following (a) and (b)). High-speed digital high-quality developing device that has 1,000,000 sheets of durability and has no sleeve pitch unevenness or sleeve ghost as images (No. (c) below). (See (d) below). In addition, a sleeve drive unit (sleeve flange shaft) connected by a high-speed motor
Alternatively, when the temperature rise of the flange shaft portion caused by the high-speed rotation is transmitted to the image area portion of the sleeve in the gap holding portion between the sleeve and the photoreceptor, deterioration of the toner characteristics due to heat is promoted, and this appears as a decrease in image density. However, by adopting the configuration of the present embodiment, by using a material in which the thermal conductivity of the flange shaft portion is smaller than that of the sleeve portion, the temperature of the image portion of the sleeve is increased by the temperature rise from the end portion peculiar to the high-speed machine. As a result, the temperature of the toner was raised to prevent a decrease in density due to thermal deterioration of the toner.

(A) Al sleeve + SUS flange Before heating Torque after heating (kg · cm) 300 or more 63 to 245 Flare (difference) 0 60 μm (b) Al sleeve + SUS flange (fit) Before heating Torque (kg · cm) before heating cm) 300 or more 170 to 368 Flare (difference) 06 μm Swelling of pipe end 36 μm 36 μm (c) Al sleeve + Al flange Before heating After heating Torque (kg · cm) 300 or more 300 or more Flare (difference) 0 3 μm Flange wear × Example (d) Al sleeve + (Al + SUS) flange Before heating After heating Torque (kg · cm) 300 or more 300 or more Flare (difference) 0 3 μm Swelling of pipe end 10 μm 10 μm Flange wear ○

The preferable difference between the thermal conductivity and the difference between the linear expansion coefficients is caused by the torque resistance (standard 200 kgf) of the sleeve and the flange and the temperature rise at the end (flange shaft) as shown in Tables 3 and 4. From the viewpoint of thermal development property lowering (density lowering) of the toner, a thermal conductivity difference of 50 W / m. It is preferably within K and within 5K ^{-1 of the} difference in linear expansion coefficient.

In the present invention, the thermal conductivity is JIS R
1611 (laser flash method).

In the present invention, the linear expansion coefficient is JIS K
6911.

[0029]

[Table 3]

[0030]

[Table 4]

[Embodiment 2] The image forming apparatus is the same as that of Embodiment 1, but is an analog machine of 80 sheets, an image is formed by analog exposure, and a negative toner (6 μm) is used as a toner. A total current of -250 μA flows through the post charger to charge and transfer the toner image. Sleeve is 30φ
A6063 was used for the Al sleeve base tube. The thickness is set to 0.8 mm, and a film in which an epoxy resin, TiO ₂ and carbon are mixed at a ratio of 100: 40: 3 is produced on the surface.

In this embodiment, the flange is made of three kinds of metals in order to minimize stress distortion caused by thermal expansion during drying of the coat of the developing sleeve due to difference in linear expansion. The A2017 of Al of FIG. 2 (2A-3) is used on the most sleeve side, and the SUS having about half the coefficient of linear expansion due to heat is used.
Instead of directly joining (see Table 1), in the present embodiment, as shown in FIG.
6.2 × 10 ⁻⁶ (K ⁻¹ )). The production method was die-cast. And 2A-5 SU on 2A-4
I put the cap of S.

As described above, by forming the flange from a plurality of metals and arranging the flanges in such a manner that the linear expansion coefficient becomes smaller in the order of increasing the distance from the sleeve, the stress distortion, torque and space due to heating during drying are reduced. The change in precision of the joint can be reduced. The SUS cap was made from SUS304. In this way, even after heating (170 ° C.) at the time of drying the coat, the torque of the joint due to the difference in thermal expansion does not decrease, and the shaft of the flange after the endurance does not scrape. It was possible to provide a digital high-quality image developing device having high durability and having no sleeve pitch unevenness and sleeve ghost as an image in a high-speed machine.

[Embodiment 3] The image forming apparatus is the same as that of Embodiment 1, and the description of the image forming process is omitted. In this embodiment, the surface of the sleeve is coated with a thermosetting phenol resin, conductive graphite, and carbon in a composition ratio of 100: 45: 5. The material of the sleeve is A2011 of Al. As shown in FIG. 3, the flange is attached to the shaft (2A-7) of SUS303 and the flange portion (2A-6) of Al by knurling to secure the torque at the joint. ,
The wear resistance of the flange shaft was guaranteed.

By adopting this structure, the manufacturing cost is further reduced, the manufacturing is easy, and the durable life of one million sheets is obtained.
As a picture, a digital high-quality developing device free of sleeve pitch unevenness and sleeve ghost could be provided in a high-speed machine.

[Embodiment 4] The image forming apparatus is the same as that of Embodiment 1, and the description of the image forming process is omitted. In this embodiment, the surface of the sleeve is coated with a film of phenol resin, conductive graphite and carbon in a composition ratio of 100: 45: 5. The sleeve tube is A6063 and its surface is FGB # 3
The surface is adjusted to Rz 3.5 μm with 00 (Fine Glass Beads) and then coated. In this embodiment, as shown in FIGS. 4-1 and 4-2, the SUS portion (2A-9) of the flange shaft is increased in both flanges to increase stability and durability during rotation of the sleeve during development. I made it. SUS part (SUS303) and Al part (S2017)
(2A-8) is a method in which a shaft is produced by a die casting method,
And are joined by metal bonding.

With this configuration, a digital high-quality image developing apparatus which has stability during rotation of the developing sleeve, has a long service life of one million sheets, and has no sleeve pitch unevenness and no sleeve ghost as an image can be used in a high-speed machine. Could be provided.

[Embodiment 5] The image forming apparatus is the same as that of Embodiment 1, and the description of the image forming process is omitted. In this embodiment, the surface of the sleeve is coated with a film of phenol resin, conductive graphite and carbon in a composition ratio of 100: 45: 5. The sleeve tube is A6063 and its surface is FGB # 3
The surface is adjusted to Rz 3.5 μm with 00 (Fine Glass Beads) and then coated. In this embodiment, as shown in FIG. 5, an Al flange (A6063)
2A-11 was prepared first, and 2A-1 was added to the shaft part.
1 SUS cap (SUS305).

According to this configuration, the manufacturing method is simpler and the configuration is simpler, so that it is inexpensive, has stability during rotation of the developing sleeve, has a long life of 1 million sheets,
As a picture, a digital high-quality developing device free of sleeve pitch unevenness and sleeve ghost could be provided in a high-speed machine.

[Embodiment 6] In this embodiment, the same system as that of the first embodiment is used, and A201 of Al is attached to the flange (2A-1).
7. SUS304 was used for the shaft (2A-2). The feature of this embodiment is that the configuration of the flange of the present invention is applied to a metal-plated sleeve.

In this embodiment, a Ni-plated sleeve is used. This is the case where the toner is a positive toner and the image characteristics of the printer are better (density, fog, sharpness, etc.) when plated with metal in accordance with the properties of the toner.

In particular, in high-speed copiers and printers, durability and temperature rise are serious problems. Therefore, plating is applied to the sleeve to improve image characteristics and durability, and to solve all problems of flange durability, reliability and temperature. This application of the flange configuration in a metal-plated development system in this respect was particularly effective.

[0043]

As described above, according to the present invention,
A developing device that realizes high-quality images without ghost images and sleeve pitch unevenness, satisfies the required torque when rotating the developer carrier, improves the wear resistance of the flange, and has a long life of the developer carrier. Made it possible to provide.

In a sleeve driving section (sleeve flange shaft section) connected by a high-speed motor or a gap holding section between the sleeve and the photosensitive member, the temperature rise of the flange shaft section caused by high-speed rotation is transmitted to the image area of the sleeve. And a developing device capable of maintaining the density by preventing the temperature of the image portion of the sleeve from rising.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a flange of a developing device for explaining a first embodiment.

FIG. 2 is a configuration diagram of a flange of a developing device for explaining a second embodiment.

FIG. 3 is a configuration diagram of a flange of a developing device for explaining a third embodiment.

FIG. 4 is a configuration diagram of a flange of a developing device for explaining a fourth embodiment.

FIG. 5 is a configuration diagram of a flange of a developing device for explaining a fifth embodiment;

FIG. 6 is a diagram illustrating a developing device.

FIG. 7 is a diagram for explaining a conventional example and a first embodiment.

FIG. 8 is a diagram illustrating a developing sleeve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drum photosensitive body (electrostatic latent image carrier) 2 Developing device 2a Developing sleeve 2b Developing device first stirring 2c Developing device second stirring 2A-1 to 2A-12 Flange 3 Primary charger 4 Transfer charger 5 Separation charger Reference Signs List 6 Cleaning device 7 Fixing device 8 Reuse toner transport pipe 9 Toner hopper 10 Post charger 11 Static eliminator 12 Image exposure 22 Toner hopper magnet roller

Claims (7)

[Claims] 1. A charging device for uniformly charging an electrostatic latent image carrier, an exposure device for forming an electrostatic latent image, and a developing device for visualizing the electrostatic latent image, wherein the developing device includes a plurality of magnetic poles. And a developer carrier comprising a non-magnetic sleeve covering the outer periphery of the magnet roll, wherein a surface of the developer carrier is coated with a resin layer or a metal plating layer containing conductive particles, and the developer The flange that supports the carrier is made of two or more types of metal members, and the part of the flange that makes contact with the sleeve has a difference between the sleeve and the coefficient of linear expansion of 5%.
(K ^-1 ) A developing device comprising the following metal and having a higher thermal conductivity than a metal constituting a portion of the flange not in contact with the sleeve. 2. The developing device according to claim 1, wherein when the metal member constituting the flange is composed of three or more kinds, the linear expansion coefficient decreases in the order of increasing the distance from the sleeve. . 3. A conductive resin layer formed on the surface of the developer carrying member is characterized in that an epoxy resin or a phenol resin is used as a resin layer, and the resin layer contains TiO ₂ or crystalline graphite. The developing device according to claim 1. 4. A method of joining a metal constituting a flange supporting the developer carrying member by welding, or after forming a metal shaft, pouring another metal into a mold, cooling, and joining by die casting. 4. The method according to claim 1, wherein:
The developing device according to any one of the above. 5. The developing device according to claim 1, wherein the method of joining the metal forming the flange supporting the developer carrier is knurling. 6. The metal constituting the flange for supporting the developer carrying member is different in metal type between a shaft portion of the flange of the developer carrying member and a joint portion with the sleeve. 6. The developing device according to any one of claims 1 to 5. 7. The linear expansion coefficient difference between the metal of the portion of the flange that contacts the sleeve and the sleeve is 5 (K ⁻¹ ) or less, and the metal of the portion of the flange that contacts the sleeve is:
The developing device according to any one of claims 1 to 6, wherein the thermal conductivity of the flange is not less than 50 (W / mK) than the metal of the portion not in contact with the sleeve.