JP3024125B2 - Cleaning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning apparatus for removing a developer such as toner adhered to an image carrier such as a photoreceptor after transfer in an image forming apparatus such as an electrophotographic copying machine.

[0002]

2. Description of the Related Art Conventionally, as a cleaning device in an image forming apparatus such as an electrophotographic copying machine, a cleaning blade made of an elastic material such as rubber is used, and one edge of the cleaning blade is attached to the surface of an image carrier such as a photoconductor. A configuration in which a developer such as a toner adhered to a surface is removed by contact is well known. The advantages of this cleaning device are that the configuration is simple, the cost is low, and the toner can be removed efficiently.

However, in this method, it is necessary to stably bring the contact edge of the cleaning blade into contact with the surface of the image carrier with a uniform pressure for a long period of time. However, the toner is fused to the edge and paper dust is caught. In addition, poor cleaning is likely to occur due to chipping of the edge due to deterioration of the blade material. Also, in a system that uses a toner having an extremely small particle diameter to improve the image quality, the adhesion of the toner adhered to the surface of the image carrier after transfer increases with the increase of the van der Waals force. Since the pressure is extremely high, when this method is used, the contact pressure of the blade must be set high. Therefore, there is a disadvantage that the blade is easily turned up due to the frictional force between the blade and the surface of the image carrier.

[0004] As an effective cleaning method in a system using a small particle diameter toner as described above, for example, a method disclosed in Japanese Patent Application Laid-Open No. 1-312578 is known. This is provided with an auxiliary brush 32 that rotates in contact with the image carrier at the upstream portion of the cleaning blade 31 as shown in FIG. 11, and as described above, the surface of the image carrier is caused by van der Waals force or the like. The toner adhered firmly is once peeled off from the surface of the image carrier by the mechanical force generated by the rotational contact of the brush, so that the adhesive force is weakened and the toner is easily cleaned by the cleaning blade. In the case of this method, there is an advantage that the cleaning of the small particle diameter toner can be performed without setting the contact pressure of the blade so high as compared with the method using only the cleaning blade.

In general, a toner further has a particle diameter (an average particle diameter of about 1 to 50 nanometers) called an external additive for ensuring powder fluidity, chargeability, transferability, and cleaning property. Of small substances are mixed. Since the mixing amount of the external additive is determined by the specific surface area of the toner, the smaller the particle size of the toner, the larger the mixing amount of the external additive. Further, it goes without saying that the more the toner is consumed during the image formation, the more the external additive reaches the cleaning unit. For example, in a system in which four color toners are sequentially developed to form a full-color image, since there are many photographic originals and the like, the amount of toner consumed is about 10 times or more that of a normal black and white original. In such a system, the amount of the external additive is very large.

In the above-described system, in the above-described blade cleaning system or the cleaning system in which the auxiliary brush and the cleaning blade are combined, a very small external additive is aggregated at the blade edge portion, and the blade is moved when the image carrier is moved. With the vibration of the edge (so-called stick-slip development), the agglomerated external additives adhere to the surface of the image carrier, causing serious image quality defects such as filming.

As a means for solving such a technical problem, a cleaning method using a belt-shaped cleaning member, that is, a so-called web is conventionally well known.
Among them, Japanese Patent Application Laid-Open No. Sho 60-6977 describes an apparatus in which a belt is brought close to the surface of an image carrier, a bias having a polarity opposite to that of toner is applied to the belt, and an ultrasonic vibration is applied to the image carrier. I have. According to this method, the toner can be removed quite efficiently, and further, since the toner and the external additive are not pressed against the surface of the image carrier, there is no sticking of the toner and the external additive to the surface of the image carrier. However, in this method, it is difficult to completely remove a very large amount of the external additive having a strong adhesive force as described above, so that the external additive accumulates on the image carrier with the repetition of image formation. Also, the image quality is deteriorated.

Japanese Unexamined Patent Publication (Kokai) No. 3-196083 discloses a belt 34 as shown in FIG. 12, wherein a part of the material is made of an ultrafine fiber fabric having a diameter of 15 μm or less. According to this method, it is possible to sufficiently clean even if the particle diameter of the toner is small, but when the amount of toner reaching the cleaning device is large, the function may not be sufficiently performed. . For example,
In a system in which a full-color image is formed by sequentially developing toners of the four colors as described above, the amount of toner consumed is about 10 times or more that of a normal black-and-white document due to photographic development and the like. . Therefore, the toner overflows at the contact portion of the belt with the surface of the image carrier, and a part of the toner may pass through the belt or adhere to the image carrier.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and even if a large amount of toner having a small particle diameter always enters a cleaning device, the toner is reliably removed from the surface of the image carrier. An object of the present invention is to provide a cleaning device that maintains good image quality for a long period by removing the external additives and fixing the external additives to the surface of the image carrier.

[0010]

That is, as shown in FIG. 1, the present invention relates to a cleaning apparatus for cleaning the surface of an image carrier, wherein the cleaning device comprises a conductive material disposed close to the surface of the image carrier. A first roll member 11, a second roll member 12 formed of an elastic material provided downstream of the image carrier in the moving direction, and an endless belt stretched over the first and second roll members. Cleaning belt 3 and a bias applying means 4 for applying a bias having a polarity opposite to the polarity of the toner to the first roll member, and the portion of the cleaning belt extending over the first roll member is provided on the surface of the image carrier. The cleaning belt, which is held in a non-contact manner with a predetermined gap with respect to the second roller member, is brought into contact with the surface of the image carrier at a predetermined pressure, and the cleaning belt is brought into contact with the surface of the image carrier. The dynamic direction is characterized in driven it to move in the opposite direction.

Further, in order to perform cleaning more effectively, a removing roll 6 for removing extraneous matter such as toner adhered to the cleaning belt 3 after cleaning.
It is preferable to provide a bias applying unit 5 for applying a bias having a polarity opposite to the polarity of the toner to the removing roll 6 and the cleaning belt 3. Thus, the removal roll 6 is brought into contact with the surface of the cleaning belt 3,
By applying a bias having a polarity opposite to the polarity of the toner by the bias applying means 5, the toner and external additives on the surface of the cleaning belt 3 are removed.

Further, the surface of the cleaning belt 3 is constituted by a brush made of a conductive fiber, and the cleaning belt 3 spanning the second roll member is brought into contact with the surface of the image carrier 1 with a predetermined interference amount. Is preferred. Here, the amount of interference means that when the second roll member 12 is gradually approached to the image carrier 1, the second roll member 12 contacts the surface of the cleaning belt 3 or the tip of the brush fiber and the surface of the image carrier. Is expressed as the distance moved toward the image carrier from the point where the contact has started.

An electric field may be generated between the second roll member 12 and the image carrier 1 by making the surface of the cleaning belt 3 conductive.

[0014]

According to the construction described above, an electric field is generated between the first roll member 11 and the image carrier 1 by the bias applying means 4 via the cleaning belt 3, and most of the toner As a result, it flies from the surface of the image carrier 1 to the first roll member 11 and is captured by the cleaning belt 3.

At this time, on the surface of the image carrier 1, a small amount of the remaining toner and many external additives having a small particle diameter are present, and these are added to the image carrier 1 at the second roll member 12. Is mechanically removed while receiving a certain degree of pressure by the cleaning belt 3 in contact with the cleaning belt 3. further,
When the bias applying means 5 and the removing roll 6 are used,
An electric field is formed between the cleaning belt 3 and the removal roll 6, whereby the attached matter such as the toner attached to the cleaning belt 3 is electrostatically removed.

As described above, the removal roll 6 is brought into contact with the surface of the cleaning belt 3 and a bias having a polarity opposite to the polarity of the toner is applied by the bias applying means 5 so that the toner or the external additive on the surface of the cleaning belt 3 is removed. The agent is removed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments shown in the accompanying drawings. FIG. 2 schematically shows a configuration of a digital color electrophotographic copying machine including a cleaning device according to a first embodiment of the present invention. In FIG. 1, a digital color electrophotographic copying machine includes a photoreceptor 21, a charger 22, an exposure unit 23, a developing rotary 24 using a two-component developer including a toner and a carrier, and a transfer roll 2.
5, a fixing device 26, and a cleaning device 10.

In this embodiment, first, the surface of the photoconductor 21 is uniformly charged by the charger 22. The exposure unit 23 irradiates light to remove the charged electric charge in the illuminated portion, thereby forming an electrostatic latent image. For example, in this digital color electrophotographic copying machine, an organic photoconductor is used as the photoconductor 21 and a laser beam is used as the exposure device 23. Thereby, the surface of the photoconductor 21 is given a negative charge by the charger 22,
A digital latent image is formed in a dot shape by the laser beam light, and a toner is applied to a portion irradiated with the laser beam light by the developing device 24 to be visualized. The developing rotary 24 is
241 for yellow, 242 for magenta, 24 for cyan
3, the developing units for the four colors of 244 for black are sequentially opposed to the surface of the photoconductor 21 by a rotary method. In this case, a negative bias is applied to each developing device, and so-called reversal development is performed.

Next, the recording paper 2 coming out of the paper cassette 28
9 arrives at the transfer corotron 30 while being electrostatically attracted to the transfer roll 25, and the transfer corotron 30 gives a charge of a polarity opposite to that of the toner from the back side of the transfer roll 25 and the recording paper 29, and the toner image is formed by the electrostatic force. Is transferred to the recording paper 29. Recording paper 2 on this transfer roll 25
No. 9 is held in a state of being attracted to the transfer roll 25 until all the transfer of the predetermined color is completed. For example, 4
In the full-color mode, the recording paper 29 passes through the transfer corotron 30 four times while adsorbing on the transfer roll 25. After all the transfer is completed, the toner image on the recording paper 29 is heated or pressed to apply
9 to form a permanent image. On the other hand, the toner T remaining on the photoconductor 21 without being transferred is removed by the cleaning device 10, and the next cycle is repeated again.

FIG. 3 is a schematic enlarged view of the cleaning device used in the first embodiment. In FIG. 1, the cleaning belt 3 includes a photosensitive member 2 at a second roll member 12.
By contacting the surface of the photoreceptor 21 at the first roll member 11 and keeping the surface of the photoreceptor 21 out of contact with the surface of the photoreceptor 21 and moving in the opposite direction (arrow B) to the moving direction (arrow A) of the photoreceptor 21, The transfer residual toner 51 on the photoreceptor surface is removed, and then the scraper 8 contacts the cleaning belt 3 to remove the toner from the cleaning belt 3.

Further, in this embodiment, a bias is applied to the first roll member 11 by the bias applying means 4. More specifically, a stainless steel roll having an outer diameter of 15 mm is used as the first roll member 11, and a 3 mm thick rubber material is attached to a stainless steel shaft having an outer diameter of 9 mm as the second roll member. Is used. Examples of the rubber material include those having elasticity such as polyurethane, silicon, and fluororubber. The rubber hardness is 30 to 8 in JIS-A hardness.
It is possible to use the one at 0 °.

The cleaning belt 3 may be a sheet made of conductive fibers such as polypropylene, nylon, polyester, and polystyrene. As for the degree of conductivity, the volume resistance value of a single fiber is 10 ¹⁰ Ωcm
The following is preferred. The first roll member 11
The cleaning belt 3 is held at a fixed distance from the surface of the photoreceptor 21 by a shaft support mechanism (not shown). The distance at this time is preferably in the range of 0.1 mm to 5 mm.
Preferably, the range is 0.5 mm to 1.5 mm.

Further, the cleaning belt 3 at the second roll member 12 is pressed against the surface of the photoconductor 21 by a pressing mechanism (not shown). At this time, the amount of interference with the surface of the photoreceptor 21 is preferably in the range of 0.1 mm to 5 mm, and more preferably in the range of 0.5 mm to 1.5 mm.
Further, the cleaning belt 3 is preferably moved in the direction of arrow B at a speed of 0.1 to 2 times the moving speed of the photoconductor 21 at the second roll member 12, and
Preferably, the speed is 0.5 to 1 times.

In the present embodiment, the bias applied to the first roll member 11 is preferably from +50 V to +500 V, more preferably from +100 V to +300 V, since the polarity of the toner is negative. FIG. 4 shows a second embodiment of the cleaning device to which the present invention is applied. The cleaning belt 3 is also stretched over the opposing roll 13, and the removing roll 6 is brought into contact with the cleaning belt 3 at the position of the opposing roll 13. The bias is applied to each of the roll member 11 and the removal roll 6. In the figure,
As the removing roll 6, an aluminum roll having an outer diameter of 10 mm and the surface of which is insulated is used. As the surface insulating treatment, alumite treatment or Teflon treatment is preferable.

The bias applied to the removing roll 6 has the same polarity as the bias of the first roll member 11 and preferably has a higher value. In the present embodiment, the bias of the first roll member 11 is preferably set to be higher than +50 V to +500 V, and more preferably, higher than +100 V to +300 V. Further, the rotational movement speed of the removing roll 6 is preferably about 0.5 to 2 times the moving speed of the cleaning belt 3 at the contact position with the cleaning belt 3, in a ratio thereof.
The direction is the same as that of the cleaning belt 3.

In addition, the materials and the moving direction of the first roll member 11, the second roll member 12, and the cleaning belt 3, the positional relationship with the photosensitive member 21, the bias, and the like are the same as those in the first embodiment. In this case, the toner on the cleaning belt 3 can be effectively electrostatically cleaned by biasing the removing roll 6 with the bias applying unit 5.

FIG. 5 shows a third embodiment of the cleaning apparatus to which the present invention is applied.
In this embodiment, the surface is formed of a conductive brush as shown by the arrow, and the other configuration is the same as that of the second embodiment. The brush portion of the cleaning belt 7 is made of conductive fiber such as polypropylene, nylon, etc.
It has a denier thickness and a fiber length of 3 to 7.5 mm. In this case, the brush fibers may be planted on the base fabric by a so-called U-weave, a W-weave, or a loop-like weave.

In this case, the brush fibers on the cleaning belt at the second roll member 12
The surface is contacted with an interference amount of 0.5 mm to 1.5 mm, and the interference amount can be arbitrarily set within this range, so that the allowable value at the time of setting can be extended. Next, Examples 1, 2 and 3
11 and a conventional cleaning device (comparative example) shown in FIG. 11 were mounted on a commercially available copying machine (A color 635, manufactured by Fuji Xerox Co., Ltd.) and
A copy confirmation test of 000 sheets was performed.

In this test, an organic photoreceptor (outer diameter 84 mm) having sensitivity to infrared light was used as the photoreceptor. The process speed is 160 mm / sec. Further, as a developer, a color toner (average particle diameter of each color is 7 μm) in which yellow, magenta, cyan and black pigments are dispersed;
Ferrite carriers mixed with each other at a ratio of about 8% by weight were used. The charge amount of the toner at this time was about -20 μC / g. The surface potential at the developing position of the photoreceptor was set at about -200 V in the image area, about -600 V in the non-image area, and the developing bias was set at about -500 V.

The conditions in each embodiment are as shown in Table 1 below. The conventional cleaning device shown in FIG. 6 as a comparative example is a cleaning device using a brush 32 and a blade 31, which is disclosed in Japanese Patent Application Laid-Open No. Hei 1-312578. The condition is that the brush 32 is made of nylon, denier 10d (160/16), density 48,000 pcs / inch ² ,
A pile height of 6.5 mm and an outer diameter of 20 mm were used.
The rotation speed was implemented at 220 rpm. The blade 31 was made of urethane (238707 manufactured by Hokushin Kogyo KK) and had a thickness of 2 mm and a free length of 10 mm.

[0031]

[Table 1] Table 2 shows the cleaning performance for every 10,000 sheets and the presence or absence of white spots in the copy due to the adhesion of the toner or the external additive to the surface of the photoreceptor. According to these results, the cleaning apparatuses of Examples 1, 2 and 3 were all better than the cleaning apparatuses of the comparative examples.

[0032]

[Table 2] By the way, the conventionally existing removing member 3 shown in FIG.
In the cleaning device using the cleaning device 3, the blade 31 scrapes off the toner, and the brush 32 rotates to contact the surface of the photoconductor 21 to clean the surface of the photoconductor. Thereafter, the removing member 33 contacts the brush 32. Thus, the toner is removed from the brush 32.

[0033]

As described above, according to the present invention, the conductive cleaning belt is placed on the surface of the image bearing member.
The cleaning belt at the upstream portion is kept out of contact with the surface of the image carrier with respect to the moving direction of the surface of the image carrier, and the cleaning belt at the downstream portion is brought into contact with the surface of the image carrier, and a bias is applied. After removing most of the toner lightly by electrostatic force without pressing most of the toner against the surface of the image carrier, further remove the remaining toner and external additives from the surface of the image carrier by mechanical force. Can be
As a result, filming due to the adhesion of toner and external additives to the surface of the image carrier and the phenomenon of scratching the surface of the image carrier can be eliminated, and good image quality can be maintained for a long time. Since most of the toner has already been removed at the upstream part, an expensive 15 μm
It is not necessary to use the following ultra-fine fiber knitted fabric, and the cost can be reduced.

Further, after the image carrier is cleaned, a removing roll is provided to remove the adhered matter such as toner attached to the cleaning belt, and a bias having a polarity opposite to the polarity of the toner is applied to the removing roll and the cleaning belt. By providing the bias applying means for performing the cleaning, the cleaning belt can be always kept in a clean state, and the cleaning performance of the surface of the image carrier can be more reliably performed, so that more excellent image quality can be maintained for a long time. Also, in this case,
Since it is not necessary to generate a large load on the cleaning belt, it is possible to prevent a reduction in the driving torque of the cleaning belt, uneven tension, twisting of the belt, and the like.

Further, the surface of the cleaning belt is constituted by a brush made of conductive fibers, and the cleaning belt at the downstream portion is brought into contact with the surface of the image carrier with a predetermined amount of interference, whereby the amount of interference is reduced by the brush fiber. Can be arbitrarily set by the length of, so that the allowable width at the time of setting can be expanded.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a cleaning device according to the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of an electrophotographic copying machine including a cleaning device according to a first embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a basic configuration of a cleaning device according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a basic configuration of a cleaning device according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a basic configuration of a cleaning device according to a third embodiment of the present invention.

FIG. 6 is a schematic view showing an example of a conventional cleaning device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image carrier 3 cleaning belt 4, 5 bias applying means 6 removal roll 11 first roll member 12 second roll member

Continuation of the front page (56) References JP-A-57-64275 (JP, A) JP-A-60-6977 (JP, A) JP-A-60-6976 (JP, A) JP-A-1-312578 (JP) , A) JP-A-3-196083 (JP, A) JP-A-62-294884 (JP, A) JP-A-57-57464 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB) G03G 21/10-21/12 G03G 13/14-13/16 G03G 15/14-15/16 103

Claims (3)

(57) [Claims] 1. A cleaning device for a surface of an image carrier, comprising: a first roll member made of a conductive material disposed close to the surface of the image carrier; A second roll member made of an elastic material, an endless cleaning belt stretched over the first and second roll members, and a bias having a polarity opposite to the polarity of the toner on the first roll member. And a bias applying means for applying a bias voltage, and a portion of the cleaning belt extending over the first roll member is held in a non-contact manner with a predetermined gap with respect to the surface of the image carrier, and is fixed to the second roll member. A portion of the cleaning belt to be bridged is brought into contact with the surface of the image carrier at a predetermined pressure, and the cleaning belt is driven so as to move in a direction opposite to a moving direction of the surface of the image carrier. Device. 2. A cleaning device according to claim 1, further comprising: a cleaning roller for cleaning the surface of the image carrier after removing the toner and the like, and applying a bias having a polarity opposite to that of the toner to the cleaning roller. 2. The cleaning apparatus according to claim 1, further comprising a bias applying unit for performing the cleaning. 3. The surface of the cleaning belt is formed of a brush made of conductive fibers, and the cleaning belt stretched over a second roll member is in contact with the surface of the image carrier with a predetermined interference amount. The cleaning device according to claim 1, wherein: