JPH10333514A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the movement of toner, to easily recover/remove reversely polarized toner in the toner remaining after transfer is performed as well and to enhance the recovery capacity of a cleaning roller by allowing plural cleaning rollers to which a cleaning bias is applied to contact with a photoreceptor drum, at rotational speeds different from each other. SOLUTION: A cleaning device 100 consists of the cleaning rollers 110a and 110b which come into contact with the photoreceptor drum 10 and rotate in the same direction as the rotational direction of the drum 10. Then, a toner recovering bias having a polarized opposite to that of the toner is applied to the cleaning rollers 110a and 110b from a common cleaning bias E1, to recover negatively polarized toner remaining on the drum 10, after the transfer is performed. In such a case, the small- and large-diameter cleaning rollers 110a and 110b arranged on the upstream and downstream sides in the rotational direction of the drum 10 respectively are forcedly rotated with respect to the rotary drum 10, at the rotational speeds different for each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., which forms an image by arranging a charging means, an image exposing means, a developing means and the like around an image forming body. The present invention relates to an image forming apparatus of the type.

[0002]

2. Description of the Related Art Conventionally, as one type of an electrophotographic image forming apparatus, a charging means, an image exposing means and a developing means are arranged around an image forming body, and the charging of the image forming body by the charging means and image exposure are performed. An image forming apparatus is used in which a latent image is formed on an image forming body by means of an image exposing means, and the latent image is formed by contact reversal development by a developing means.

On the other hand, in order to effectively use the toner, after the image formation, the transfer residual toner remaining on the image forming body is cleaned by a cleaning means, and the cleaning toner is conveyed to a developing means using a screw pipe or the like. A toner recycling method for reuse in the process is generally used. However, since the mechanism of the toner recycling method of transporting the cleaning toner using the screw pipe is complicated, a roller-shaped member is used as the cleaning means, and the transfer residual toner in the image area on the image carrier is temporarily removed from the image forming body. The toner on the cleaning means is discharged (adhered) again to the image forming body in the non-image area and transported to the developing means. The developing means transfers the toner on the image forming body to the inside of the developing means. JP-A-8-166750, JP-A-8-166750,
Nos. -152832, 8-6454 and 6-
No. 51672 is proposed.

[0004]

However, in the cleaning means proposed above, the transfer residual toner on the image forming body has a strong adhesion to the image forming body, and the transfer residual toner on the cleaning means can be collected well. Or not
There is a problem in that the toner (adhered toner) discharged from the cleaning unit to the image forming body has a strong adhesive force to the image forming body, and the toner is not properly collected from the image forming body by the developing unit.

The present invention solves the above-mentioned problems, and recovers the transfer residual toner on the image forming body to the cleaning means, discharges the collected toner to the image forming body from the cleaning means, and discharges the recovered toner to the image forming body. It is an object of the present invention to provide an image forming apparatus in which toner adhered on an image forming body can be favorably collected by a developing unit.

Further, in the cleaning means proposed above, it is difficult to collect a large amount of toner by using a roller-shaped cleaning means, especially when a cleaning roller having a small diameter is used or when the image forming body is rotated. With high-speed, high-speed printers, the recovery capability becomes a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which can solve the above-mentioned problems and improve the collecting ability of a roller-shaped cleaning means.

Further, according to the recovery and discharge of the transfer residual toner using the cleaning means proposed above, there is a problem that the opposite polarity toner in the transfer residual toner is not recovered and the reverse polarity toner accumulates in the developing means. Occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which solves the above-mentioned problems and in which the opposite polarity toner in the transfer residual toner is collected and removed.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to transfer untransferred toner adhering on a rotating image forming body to the image forming body at a contact portion with the image forming body. In the image forming apparatus, once collected by the roller-shaped cleaning means rotating in the direction, and then discharged onto the image forming body again,
A plurality of cleaning units to which a cleaning bias for a cleaning unit for toner recovery or toner discharge is applied are provided, and the plurality of cleaning units have different rotation speeds and abut on the image forming body. (First invention).

[0011] Further, the object of the present invention is to provide an image forming apparatus in which transfer residual toner adhered to a rotating image forming body is brought into contact with the image forming body and rotates in the same direction as the image forming body at a contact portion with the image forming body. In an image forming apparatus which once collects toner into a roller-like cleaning means and discharges the toner onto the image forming body again, a plurality of cleaning means are provided, and the plurality of cleaning means have the same polarity but different toner collection or toner discharge values. A cleaning bias applied to a cleaning unit disposed upstream of the image forming body in the rotation direction of the image forming member in the cleaning units of the plurality of cleaning units when toner is collected. Value of V11
Is set to be lower than a value V12 of the cleaning unit cleaning bias applied to the cleaning unit disposed on the downstream side (second invention).

[0012] Further, the above object is to provide a transfer residual toner adhered to a rotating image forming body in contact with the image forming body and to rotate in the same direction as the image forming body at a contact portion with the image forming body. In an image forming apparatus that once collects in a roller-shaped cleaning unit and then discharges it onto the image forming body again, a plurality of cleaning units are provided, and a support roller that rotates in contact with the plurality of cleaning units is provided, This is achieved by an image forming apparatus wherein the plurality of cleaning units contact the support roller at a rotation speed different from the rotation speed of the support roller (third invention).

The object of the present invention is also to provide an image forming apparatus in which a transfer residual toner adhered to a rotating image forming body is brought into contact with the image forming body and rotates in the same direction as the image forming body at a contact portion with the image forming body. In an image forming apparatus which collects the toner once on a roller-shaped cleaning unit and then discharges the toner onto the image forming body again, a plurality of cleaning units are provided, and when the toner is collected from the image forming body, the plurality of cleaning units have different polarities. The fourth aspect of the present invention is achieved by an image forming apparatus characterized in that a cleaning bias for a cleaning unit is applied.

[0014]

Embodiments of the present invention will be described below. The description of the present application does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.

An image forming process according to an embodiment of the image forming apparatus of the present invention and the structure and function of each mechanism will be described with reference to FIGS. FIG. 1 is a sectional view of a laser printer showing an embodiment of the image forming apparatus of the present invention, and FIG. 2 is a view showing a first example of toner collection and discharge by a plurality of cleaning means. 3 is a diagram showing an operation range of a cleaning unit cleaning bias, FIG. 4 is a diagram showing a method of collecting untransferred toner to a developing unit, and FIG. 5 is a first example of a structure of the cleaning unit. FIG. 6 is a cross-sectional view showing second and third examples of the structure of the cleaning unit, and FIG.
FIG. 6 is a sectional view showing a second example of the structure of the cleaning means, and FIG. 6B is a sectional view showing a third example of the structure of the cleaning means.

1 to 4, the photosensitive drum 10 as an image forming body has a peripheral speed (linear speed) of 150 m, for example.
At a speed of m / sec, it is driven and rotated in the direction indicated by the arrow in FIG. 1 and is uniformly distributed by corona discharge of the same polarity as toner (minus polarity in this embodiment) on the peripheral surface by a scorotron charger 11 as a corona charger. After being charged, image exposure based on an image signal is performed by an exposure optical system 12 as image exposure means. The exposure optical system 12 rotationally scans laser light emitted from a laser light source (not shown) by a rotary polygon mirror 12b, and forms a latent image on the photosensitive drum 10 via an fθ lens 12c, a reflection mirror 12d, and the like.

A developing device 13 is provided as developing means for developing with a one-component developer or a two-component developer composed of toner or toner and carrier, and develops a latent image formed on the photosensitive drum 10. Is performed by the developing sleeve 13a that carries the developer. Development is development sleeve 1
The development is performed by contact reversal development in which a DC developing bias having the same polarity as the toner (in this embodiment, a negative polarity) is applied between the photosensitive drum 3a and the photosensitive drum 10. As the toner used for the developer, a spherical toner having high recovery efficiency of the transfer residual toner described later is preferably used.

A recording sheet P, which is a transfer material, is sent out from a paper feed cassette 15 serving as a transfer material storage means by a feed roller 15a, fed by a feed roller 15b, and conveyed to a timing roller 15c.

The recording paper P is synchronized with the toner image formed on the photosensitive drum 10 by the driving of the timing roller 15c, so that the driving roller 14d and the driven roller 1d are driven.
A transfer belt 14a, which is provided with a transfer belt 14a stretched between the transfer belt 4e and a tension roller 14i, is transferred to a nip portion (transfer area) 14b formed between the photosensitive drum 10 and the transfer belt 14a by a transfer belt device 14 as a transfer unit. The transfer device 14c is provided opposite to the photosensitive drum 10 with the transfer belt 14a interposed therebetween, and is applied with a transfer voltage of a polarity opposite to that of the toner (positive polarity in the present embodiment). Are collectively transferred onto the recording paper P.

If a corona transfer device directly facing the image forming member is used as the transfer means, the toner polarity is inverted by corona discharge with respect to the toner in the absence of the transfer material or the toner outside the transfer material even if the transfer material is present. (The positive polarity in the present embodiment), and the recovery of the transfer residual toner on the image forming body by a cleaning unit to which a bias having a polarity opposite to the toner described later (positive polarity in the present embodiment) is applied. Make it difficult. In the above-described transfer belt or transfer roller, the transfer belt or transfer roller is preferable because the toner outside the transfer material is transferred to the transfer unit side with the negative polarity without reversing the polarity, and the load on the cleaning unit is reduced. Used.

The recording paper P separated from the transfer belt device 14 by a separator 14h as a transfer material separating means is supplied to a fixing device 17 having a heating fixing roller 17a having a heater inside at least one of the rollers and a pressure roller 17b.
Is applied to the recording paper P by applying heat and pressure between the heating fixing roller 17a and the pressure roller 17b, and is discharged to the outside of the apparatus by the discharge roller 18. .

The toner remaining in the untransferred toner area on the peripheral surface of the photosensitive drum 10 after the transfer of the image forming area where the toner image is to be formed is removed by the light erasing device 16 as the erasing means.
Then, the potential level of the photosensitive drum 10 is reduced to substantially zero, and then the cleaning device 100 is reached.

The cleaning device 100 is provided in a cleaning casing 110d, and is constituted by two roller-shaped cleaning means which abut on the photosensitive drum 10 and rotate in the same direction as the rotating direction of the photosensitive drum 10 in the cleaning section. Is done. In the cleaning section, an upstream cleaning roller 110a as a cleaning unit is disposed on the upstream side in the rotation direction of the photoconductor drum 10, and a downstream cleaning roller 110b as a cleaning unit is disposed on the downstream side in the rotation direction of the photoconductor drum 10. Is done. The outer diameter of the upstream cleaning roller 110a is set smaller than the outer diameter of the downstream cleaning roller 110b.

The two cleaning means are connected to a cleaning roller cleaning bias E1 as a common cleaning means cleaning bias, and the respective cleaning rollers 110a and 110b are connected by the cleaning roller cleaning bias E1 in FIG.
A toner collection bias of a value V1 of about 300 to 1500 V having a polarity opposite to that of the toner indicated by the solid line (positive polarity in the present embodiment) is applied, and the negative transfer residual toner on the photosensitive drum 10 is removed from the cleaning roller 110.
a and 110b are collected on the outer peripheral surface. In order to completely recover the transfer residual toner in the transfer residual toner region, the toner recovery bias application region is formed to be slightly longer on both sides than the image forming region.

The potential level of the photosensitive drum 10 is reduced to substantially zero by the light neutralization of the light neutralizer 16, so that the electrostatic attraction of the transfer residual toner to the photosensitive drum 10 is weakened, and the transfer residual toner is easily moved. In addition, transfer to the cleaning rollers 110a and 110b to which a toner collection bias having a value V1 of a polarity (positive polarity) opposite to that of the transfer residual toner is applied is facilitated, and the collection efficiency is improved.

In the cleaning section, the photosensitive drum 10 rotated at the rotation speed S is changed.
Cleaning roller 1 disposed on the upstream side in the rotation direction 0
The rotational speed of the cleaning roller 110a is set to S1 and the rotational speed of the cleaning roller 110b disposed on the downstream side is set to S2. , And the cleaning unit rotates the cleaning rollers 110a and 110b in the same direction as the rotation direction of the photosensitive drum 10 at different rotational speeds.

A speed difference is provided between the rotation speeds of the cleaning rollers 110a and 110b and the rotation speed of the photosensitive drum 10, and the cleaning rollers 110a and 110b are deviated from the photosensitive drum 10 to forcibly drive and rotate the photosensitive drum 10.
The adhesion of the transfer residual toner is mechanically weakened to facilitate the movement of the toner. The speed difference between the cleaning rollers 110a and 110b with respect to the photosensitive drum 10 is 1 to 10
% Is preferred. That is, the rotation speed of the photoconductor drum 10 is S, the rotation speed of the cleaning roller 110a disposed on the upstream side in the rotation direction of the photoconductor drum 10 is S1, and the cleaning roller 110b is disposed on the downstream side in the rotation direction of the photoconductor drum 10. Assuming that the rotation speed of the motor is S2, 0.9 ≦ |
(S1-S) /S|≤0.99, 0.9≤ | (S2-
S) /S|≦0.99, and the cleaning roller 11
If the speed difference between the photosensitive drum 10a and the photosensitive drum 10b is less than 1%, the effect of weakening the adhesive force is not sufficient, and if it exceeds 10%, the speed difference is too large, and
Toner filming to 0 or toner scattering occurs.

Further, it is preferable that the rotation speed of one of the rollers is higher and the rotation speed of the other roller is lower than the rotation speed of the photosensitive drum 10, and that the rotation speed of the other roller is particularly high. The rotation speed S1 of the cleaning roller 110a is higher than the rotation speed S of the photosensitive drum 10, and the rotation speed S2 of the cleaning roller 110b disposed on the downstream side in the rotation direction of the photosensitive drum 10.
Is preferably smaller than the rotation speed S of the photosensitive drum 10 (S2 ≦ S ≦ S1). Cleaning roller 110 arranged upstream at a higher speed than photoconductor drum 10
a, the untransferred toner is extruded downstream, and the untransferred toner is extruded upstream by a cleaning roller 110 b arranged at a lower speed than the photosensitive drum 10, and the toner moves back and forth on the photosensitive drum 10. It is displaced in the direction, making recovery easier.

As described above, by causing the plurality of cleaning means to contact the image forming body at different rotational speeds, the toner is easily moved, and toner collection and toner discharge by the cleaning means are facilitated. Further, by reducing the speed difference between the cleaning means and the image forming body and slowly rubbing the image forming body with the cleaning means, the transfer residual toner on the image forming body is rubbed in the moving direction of the image forming body, Is weakened, the toner is shifted on the image forming body, the toner is easily moved, and the collection becomes easier.

Further, by increasing or decreasing the rotation speed of the plurality of cleaning means with respect to the rotation speed of the image forming body, a different force is applied to the toner so that the toner adheres to the image forming body and the cleaning means. And the toner is easily collected and discharged by the cleaning means. Particularly, the transfer residual toner is extruded to the downstream side by the cleaning means arranged at a higher speed than the image forming body, and the transfer residual toner is moved to the upstream side by the cleaning means arranged at a lower speed than the image forming body. The toner is extruded, and the toner moves on the image forming body in the front-rear direction, thereby facilitating the recovery. In particular, the rotation speed S1 of the cleaning unit disposed on the upstream side in the rotation direction of the image forming body is reduced. The rotation speed S is higher than the rotation speed S, so that the toner is entangled in the cleaning device, so that the inside of the device due to the toner falling down is prevented, and the cleaning device disposed on the downstream side in the rotation direction of the image forming body. Is smaller than the rotation speed S of the image forming body, the toner is drawn out to the upstream side of the image forming body. To prevent contamination of the charging means by the toner release.

Next, in the non-image forming area between the image forming areas after passing through the transfer residual toner area, the cleaning bias E1 for the cleaning roller applied to the cleaning rollers 110a and 110b is changed to the toner indicated by the dotted line in FIG. The toner discharge bias is switched to a toner discharge bias having a value V2 of about -300 to -1500 V to which the same polarity (minus polarity in the present embodiment) is applied, and the collected toner on the respective cleaning rollers 110a and 110b is discharged onto the photosensitive drum 10 ( Adhere). At this time, as shown in FIG. 3, the toner discharge bias application area from the start of the application of the toner discharge bias to the cleaning roller 110a to the stop of the application of the toner discharge bias to the cleaning roller 110b is:
This is between toner application bias application areas from the start of application of the toner collection bias to the cleaning roller 110a to the stop of application of the toner collection bias to the cleaning roller 110b, and is slightly higher than between image formation areas (non-image formation area). The length is set to be short so that all the collected toner on the cleaning rollers 110a and 110b is discharged (adhered) onto the photosensitive drum 10. At this time,
The photosensitive drum 10 is subjected to light elimination by the light eliminator 16. The potential level of the photosensitive drum 10 is reduced to substantially zero by the light elimination, thereby facilitating the adhesion of the discharged toner to the photosensitive drum 10.

As shown in FIG. 4A, a toner layer is formed on the photosensitive drum 10 whose potential level is substantially zero. The attached toner is attached to the photosensitive drum 10 with a negative polarity due to the toner discharge bias, and the potential level of the toner layer is approximately -50V.

Subsequently, the surface potential of the photosensitive drum 10 is applied to the photosensitive drum 10 to which the discharged toner is attached by a DC voltage of the same polarity as the toner (minus polarity in this embodiment) by a scorotron charger 11 as charging means. But-
When the recharging is performed at 750 V, as shown in FIG. 4B, the potential level on the surface of the photosensitive drum 10 is charged to, for example, about -650 V, and the potential level of the toner layer adhered becomes Due to the recharging, the voltage slightly increases to about -100V.

In this state, the discharged toner that has been recharged and adhered to the photosensitive drum 10 reaches the developing unit 13 and, as shown in FIG. 4C, has the same polarity as the toner lower than the photosensitive member potential (this embodiment). In the negative polarity) -100 ~
The photosensitive drum 10 is cleaned (recovered) from the photosensitive drum 10 by being rubbed by the developer on the developing sleeve 13a of the developing device 13 to which the -650 V cleaning developing bias is applied. At this time, even if all the toner is not collected, the toner is not used for the next image forming area, so that there is no problem in the image. The toner is attracted to the developing sleeve 13a by setting the cleaning developing bias equal to or lower than the developing bias used for reversal development during image formation.

The photosensitive drum 10 from which the residual toner has been removed by the cleaning device 100, the scorotron charger 11 and the developing device 13 is uniformly charged again by the scorotron charger 11, and enters the next image forming cycle.

Cleaning roller 1 in the above description
In the toner collection and toner discharge by 10a and 110b, the photoreceptor potential has irregularities if there is no light elimination by the light eliminator 16 as the charge elimination means. Not reduced. For this reason, photoremoval is performed to smooth the potential of the photoconductor, thereby enabling uniform and high recovery or discharge. This facilitates toner collection by the developing means. Further, since the toner is attracted to the photosensitive drum 10 by electrostatic electric force and does not stain the charging means at the time of recharging, a charging roller can be used as the charging means.

As a developing method, a two-component magnetic brush development, a one-component magnetic brush development or a one-component non-magnetic development is used so that the toner discharged by the cleaning means can be easily collected from the photosensitive drum 10 to the developing device 13. . Further, the toner used for the developer is preferably a spherical polymerized toner (spherical toner) capable of high image quality. Since the toner is spherical, the mechanical adhesion to the photosensitive drum 10 is small, and the electrostatic adhesion of the particles is also small. Adhesion is small, and it has higher recovery efficiency and higher discharge efficiency as compared with pulverized toner (irregular toner). Conventionally, when cleaning with a general rubber blade, it is possible to use a spherical toner that is more likely to be rubbed off than a blade.

In the above-described embodiment, the cleaning rollers 110a and 110b as the cleaning means have the mechanical characteristics of an appropriate contact pressure with the image forming body and the electric characteristics of providing the transfer residual toner with an adequate amount of charge. It becomes important.

As mechanical characteristics, the cleaning roller 1
Regarding the relationship between the contact pressure of the image forming members 10a and 110b and the collection efficiency, generally, as the contact pressure increases, the collection efficiency increases and the collection variation also decreases. However, when the contact pressure becomes excessive, partial cleaning failure occurs in the image forming area or at the end. This phenomenon is due to the fact that the toner layer is pressed against the surface of the photoreceptor drum 10 and the untransferred toner aggregates, thereby increasing the mechanical adhesion. In particular, it tends to occur when the pressure of the cleaning rollers 110a and 110b is too high, when the toner layer is thick, or when the toner fluidity is poor. For this reason, the cleaning rollers 110a and 110b, which are the cleaning means, need to have soft elastic characteristics that do not cause agglomeration of the untransferred toner, and have a function in which the electrical and mechanical characteristics shown in FIG. Is preferred. Reference numeral 111 denotes a metal shaft, 112 denotes a conductive sponge, 113 denotes a sponge rubber, 114 denotes a conductive layer, and 115 denotes a resistance layer covering the outer peripheral surface of the conductive layer 114.
0b is configured.

Further, since the cleaning loss is caused by a strong mechanical adhesive force, as described above, a speed difference is provided between the cleaning rollers 110a and 110b and the photosensitive drum 10, and the toner is moved in the moving direction of the photosensitive drum 10. To reduce the mechanical adhesive force between the photosensitive drum 10 and the transfer residual toner, thereby reducing cleaning omission. For example, when the speed of the photoconductor drum 10 is 150 mm / sec, if a speed difference of about several percent is provided, cleaning omission can be greatly reduced, and the speed of the photoconductor drum 10 becomes 80 to 350 mm / s.
In the case of ec, a speed difference of 1 to 10% is preferable as described above.

The cleaning roller 11 has electrical characteristics.
It is important to select the roller resistances 0a and 110b. If the roller resistance is too low, abnormal discharge occurs at the contact portion between the photosensitive drum 10 and the cleaning rollers 110a and 110b, and the concentration of current may cause the destruction of the photosensitive drum 10. If the roller resistance is low, the collection efficiency is significantly reduced in a high-temperature, high-humidity environment. This is because a low resistance roller tends to inject a reverse charge from the roller into the toner, and reduces the toner charge amount to weaken the electrostatic force. Conversely, in a high-resistance roller, the electric field applied to the toner is reduced, and the collection efficiency is reduced. Cleaning rollers 110a, 110b
Is 10 ⁸ to 10 ¹² Ω · cm.

The resistance value of the cleaning roller 110a, 110b or the recording paper P as a transfer material depends on the atmosphere.
It changes by an order of magnitude, and the recovery characteristics change accordingly. For this reason, stable recovery cannot be performed by constant voltage control with respect to environmental fluctuations. On the other hand, in the constant current control, stable recovery is performed with high resistance to environmental fluctuations. Alternatively, a method of performing a constant voltage control by selecting an applied voltage of the cleaning rollers 110a and 110b stored in a ROM table, for example, as an arithmetic process from an appropriate current value of the cleaning rollers 110a and 110b capable of excellent recovery may be adopted. It is possible.

As another structure of the cleaning means, as shown in FIG.
Thickness 5 mm, surface roughness Rz = 8 μm or less, hardness 30 to
A conductive urethane rubber 116 having a volume resistance of 10 ⁴ to 10 ¹⁰ Ω · cm is provided at 60 degrees (Asker C: measured by an Aska C rubber hardness meter), and a thickness of about 20 μm is formed on the outer peripheral surface of the urethane rubber 116. A roller provided with a semiconductive fluororesin coating layer 117 having a surface roughness Rz of 5 μm or less can be used as the cleaning rollers 110a and 110b.

As shown in FIG. 6B, an EP having a cell diameter of 100 to 200 μm is formed on the outer periphery of the metal shaft 111.
DM (ethylene propylene die)
nubber) A conductive powder is dispersed in a foam, and the hardness is 2
5 to 40 degrees (Asker C: measured by Aska C rubber hardness tester), volume resistance 10 ⁸ to 10 ¹² Ω · cm and outer diameter 17
It is also possible to use a roller having a one-layer configuration with a rubber layer 118 of mm as the cleaning rollers 110a and 110b.

FIGS. 5, 6A and 6
The rollers described in (B) can be used as the combination cleaning rollers 110a and 110b.

In the above embodiment, it is preferable that the total pressure of the cleaning roller as a cleaning means to the image forming body is maintained at 0.5 to 2 kg. Further, in order to prevent the toner from adhering to the cleaning roller at the time of a paper jam, before printing, the non-image forming area has a polarity (in the present embodiment, about −300) of the same polarity as the toner (minus polarity).
A toner discharge bias of a DC voltage of -1500 V is applied to the cleaning roller to electrostatically discharge the toner adhered to the image forming member from the cleaning roller. In addition, the above-described bias control allows a stable recovery characteristic to be obtained for various transfer materials and various environments. Environmental fluctuations, contamination of the image forming body, soft contact with the image forming body, electrical and mechanical damage of the image forming body, hysteresis loss, cleaning of the cleaning roller to ensure good recovery and discharge operation of the cleaning roller It is important to always obtain stability in consideration of the above, and it is preferable to provide a retracting mechanism for the cleaning roller in view of contamination of the image forming body or hysteresis loss.

A second example of toner collection and discharge by a plurality of cleaning means will be described with reference to FIGS. FIG. 7 is a diagram illustrating a second example of toner collection and discharge by a plurality of cleaning units.

The toner remaining in the untransferred toner area on the peripheral surface of the photoreceptor drum 10 after the transfer of the image forming area where the toner image is to be formed is removed by the light erasing device 16 as the erasing means.
Then, the potential level of the photosensitive drum 10 is reduced to substantially zero, and then the cleaning device 100 is reached.

The cleaning device 100 is provided in the cleaning casing 110d, and is constituted by two roller-shaped cleaning means which abut on the photosensitive drum 10 and rotate in the same direction as the rotating direction of the photosensitive drum 10 in the cleaning section. Is done. In the cleaning section, an upstream cleaning roller 110a as a cleaning unit is disposed on the upstream side in the rotation direction of the photoconductor drum 10, and a downstream cleaning roller 110b as a cleaning unit is disposed on the downstream side in the rotation direction of the photoconductor drum 10. Is done. The outer diameter of the upstream cleaning roller 110a is set smaller than the outer diameter of the downstream cleaning roller 110b.

As in the first example described with reference to FIG.
With respect to the photoconductor drum 10 rotated at the rotation speed S, the cleaning unit 110 sets the rotation speed of the cleaning roller 110a arranged on the upstream side in the rotation direction of the photoconductor drum 10 in the cleaning unit to S1, and the cleaning roller 110b arranged on the downstream side.
The rotation speed of the cleaning roller 110 is S2.
a, 110b, the cleaning rollers 110a,
The cleaning rollers 110a and 11b are forcibly driven by a gear G coupled to a gear (not shown) having the same diameter as that of the cleaning rollers 110a and 110b.
0b is rotated at a different rotation speed in the same direction as the rotation direction of the photosensitive drum 10 by the cleaning unit.

The rotational speed of the cleaning rollers 110a and 110b and the rotational speed of the photosensitive drum 10 are provided with a speed difference, and the cleaning rollers 110a and 110b are deviated from the photosensitive drum 10 to be forcibly driven to rotate.
The adhesion of the transfer residual toner is mechanically weakened to facilitate the movement of the toner. The speed difference between the cleaning rollers 110a and 110b with respect to the photosensitive drum 10 is 1 to 10
% Is preferred. That is, the rotation speed of the photoconductor drum 10 is S, the rotation speed of the cleaning roller 110a disposed on the upstream side in the rotation direction of the photoconductor drum 10 is S1, and the cleaning roller 110b is disposed on the downstream side in the rotation direction of the photoconductor drum 10. Assuming that the rotation speed of the motor is S2, 0.90 ≦ |
(S1-S) /S|≤0.99, 0.90≤ | (S2-
S) /S|≦0.99, and the cleaning roller 11
If the speed difference between the photosensitive drum 10a and the photosensitive drum 10b is less than 1%, the effect of weakening the adhesive force is not sufficient, and if it exceeds 10%, the speed difference is too large, and
Toner filming to 0 or toner scattering occurs.

Further, it is preferable that the rotation speed of one roller is higher and the rotation speed of the other roller is lower than the rotation speed of the photosensitive drum 10. The rotation speed S1 of the cleaning roller 110a is higher than the rotation speed S of the photosensitive drum 10, and the rotation speed S2 of the cleaning roller 110b disposed on the downstream side in the rotation direction of the photosensitive drum 10.
Is preferably smaller than the rotation speed S of the photosensitive drum 10 (S2 ≦ S ≦ S1). Cleaning roller 110 arranged upstream at a higher speed than photoconductor drum 10
a, the untransferred toner is extruded downstream, and the untransferred toner is extruded upstream by a cleaning roller 110 b arranged at a lower speed than the photosensitive drum 10, and the toner moves back and forth on the photosensitive drum 10. It is displaced in the direction, making recovery easier.

By bringing the plurality of cleaning means into contact with the image forming body at different rotational speeds, the toner is easily moved, and the toner collection and the toner discharge by the cleaning means are facilitated. Further, by reducing the speed difference between the cleaning means and the image forming body and slowly rubbing the image forming body with the cleaning means, the transfer residual toner on the image forming body is rubbed in the moving direction of the image forming body, The mechanical adhesion to the image forming body is shifted,
The toner is easy to move, making recovery easier.

Further, by increasing or decreasing the rotation speed of the plurality of cleaning means with respect to the rotation speed of the image forming body, a different force is applied to the toner so that the toner adheres to the image forming body and the cleaning means. And the toner is easily collected and discharged by the cleaning means. Particularly, the transfer residual toner is extruded to the downstream side by the cleaning means arranged at a higher speed than the image forming body, and the transfer residual toner is moved to the upstream side by the cleaning means arranged at a lower speed than the image forming body. The toner is extruded, and the toner moves on the image forming body in the front-rear direction, thereby facilitating the recovery. In particular, the rotation speed S1 of the cleaning unit disposed on the upstream side in the rotation direction of the image forming body is reduced. The rotation speed S is higher than the rotation speed S, so that the toner is entangled in the cleaning device, so that the inside of the device due to the toner falling down is prevented, and the cleaning device disposed on the downstream side in the rotation direction of the image forming body. Is smaller than the rotation speed S of the image forming body, the toner is drawn out to the upstream side of the image forming body. To prevent contamination of the charging means by the toner release.

Unlike the first example, the two cleaning means are connected to different cleaning means cleaning biases.

At the time of toner collection, the upstream cleaning roller 110a as a cleaning means is connected to a cleaning roller cleaning bias E2 as a cleaning means cleaning bias. A toner collection bias having a value V11 having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the cleaning roller 110a, and the transfer residual toner having a negative polarity on the photosensitive drum 10 is removed from the cleaning roller 110a.
The cleaning roller 110b on the downstream side, which is collected on the outer peripheral surface of the cleaning roller 110a, is connected to the cleaning bias E3 for the cleaning roller as the cleaning bias for the cleaning means.
Is applied to the cleaning roller 110 b, and the transfer residual toner of the negative polarity on the photosensitive drum 10 is removed from the cleaning roller 1.
It is collected on the outer peripheral surface of 10a. In order to completely recover the transfer residual toner in the transfer residual toner region, the toner recovery bias application region is formed to be slightly longer on both sides than the image forming region.

The potential level of the photosensitive drum 10 is reduced to substantially zero by the light neutralization of the light neutralizer 16, so that the electrostatic attraction of the transfer residual toner to the photosensitive drum 10 is weakened, and the transfer residual toner is easily moved. Further, the transfer to the cleaning rollers 110a and 110b to which the toner collection bias of the opposite polarity (positive polarity) V11 and V12 of the toner of the transfer residual toner is applied is facilitated, and the collection efficiency is improved.

Next, the cleaning biases E2 and E3 for the cleaning rollers applied to the cleaning rollers 110a and 110b in the non-image forming area between the image forming areas after passing the transfer residual toner area are indicated by dotted lines in FIG. The toner discharge bias is switched to a value V13 or V14 to which the same polarity as the toner (minus polarity in this embodiment) is applied, and the collected toner on the cleaning rollers 110a and 110b is discharged (adhered) onto the photosensitive drum 10. . At this time, as shown in FIG. 3, the toner discharge bias application area from the start of the application of the toner discharge bias to the cleaning roller 110a to the stop of the application of the toner discharge bias to the cleaning roller 110b is applied to the toner collection bias to the cleaning roller 110a. The interval between the toner collecting bias application areas from the start to the stop of the application of the toner collecting bias of the cleaning roller 110b is set to be slightly shorter than the interval between the image forming areas (non-image forming area).
All the collected toner on 110b is discharged (adhered) onto the photosensitive drum 10. At this time, the photosensitive drum 10 is further subjected to light neutralization by the light neutralizer 16. The potential level of the photosensitive drum 10 is reduced to substantially zero by the light elimination, thereby facilitating the adhesion of the discharged toner to the photosensitive drum 10.

In the above-described toner collection or toner discharge, when the toner is collected, the cleaning section of the cleaning unit applies a cleaning roller cleaning bias applied to the cleaning roller 110a disposed on the upstream side in the rotation direction of the photosensitive drum 10. The value V11 of the toner collecting bias of the cleaning roller E3 applied to the cleaning roller 110b disposed on the downstream side is set to the value V1 of the toner collecting bias of the cleaning roller E3.
2, the toner discharge bias value V13 of the cleaning roller cleaning bias E2 applied to the cleaning roller 110a disposed on the upstream side in the rotation direction of the photosensitive drum 10 is set in the cleaning section when the toner is discharged. , The toner discharge bias value V14 of the cleaning roller cleaning bias E3 applied to the cleaning roller 110b disposed on the downstream side.
Set lower than. Thus, at the time of toner collection, a large amount of toner is not collected at one time, and the transfer residual toner that could not be collected on the upstream side is collected by a high toner collection bias applied to the cleaning means on the downstream side. Applying a voltage higher than that of the cleaning means on the upstream side is not preferable because the toner and the image forming body are charged by the discharge. Further, at the time of discharging the toner, since the toner on the downstream side is discharged onto the discharged toner layer on the upstream side, it is preferable that the applied voltage of the cleaning means on the downstream side is higher than that on the upstream side.

The voltage value of the toner collecting bias V11 is preferably 0.3 to 0.7 times about 1/2 of the toner discharging bias value V12, and the toner collecting bias value V13 is the value of the toner collecting bias. It is preferable that the value of the toner collection bias V11 of the same polarity as the toner (negative polarity in this embodiment) is −300 to −1500 V, and the polarity opposite to the toner ( In the present embodiment, the value V13 of the toner discharge bias (positive polarity) is preferably +300 to +1500 V in order to perform good recovery and discharge.

As described above, the toner is moved by applying a cleaning bias for the cleaning means for collecting or discharging the toner having the same polarity and different values to the plurality of cleaning means and bringing the cleaning means into contact with the image forming member. This facilitates the collection and discharge of toner by the cleaning means. In particular, in the cleaning unit, the transfer residual toner on the image forming body is removed once by a cleaning unit arranged on the upstream side in the rotation direction of the image forming body, and further, the unremoved toner is arranged on the downstream side. It is completely removed by means. Further, by making the cleaning device cleaning bias of the cleaning device disposed on the downstream side in the rotation direction of the image forming member larger at the time of toner collection or toner discharge than the cleaning device cleaning bias of the cleaning device disposed on the upstream side, In particular, the toner not removed by the upstream cleaning means at the time of collection is removed by the downstream cleaning means, and also at the time of discharge, the toner from the downstream cleaning means is placed on the toner discharged by the upstream cleaning means. It is discharged well.

In the above example, the cleaning rollers 110a and 110b as cleaning means include:
A member having the same structure as that described with reference to FIGS. 5 and 6 is used.

A third example of toner collection and discharge by a plurality of cleaning means will be described with reference to FIGS. FIG. 8 is a diagram illustrating a third example of toner collection and discharge by a plurality of cleaning units.

The toner remaining in the untransferred toner area on the peripheral surface of the photoreceptor drum 10 after the transfer of the image forming area where the toner image is to be formed is removed by the light erasing device 16 as the erasing means.
And the potential level of the photosensitive drum 10 is reduced to substantially zero, and then the cleaning device 100a is reached.

The cleaning device 100a includes a light neutralizer 16 disposed therein and a cleaning casing 110.
d, two cleaning means in the form of rollers, which contact the photosensitive drum 10 and rotate in the same direction as the rotation direction of the photosensitive drum 10 in the cleaning section, and contact the two cleaning means. It is constituted by a support roller 110c which rotates in the same direction as the cleaning means at the contact portion. Photoconductor drum 1 in cleaning section
An upstream cleaning roller 110a as a cleaning unit is provided on the upstream side in the rotation direction of 0, and a downstream cleaning roller 110b as a cleaning unit is provided on the downstream side in the rotation direction of the photosensitive drum 10. The outer diameter of the upstream cleaning roller 110a is set smaller than the outer diameter of the downstream cleaning roller 110b.

The photosensitive drum 10 rotated at the rotation speed S
On the other hand, a cleaning roller 110a disposed on the upstream side in the rotation direction of the photosensitive drum 10 in the cleaning section
The rotation speed of the cleaning roller 110c is forcibly driven by the support roller 110c rotated while being in contact with the cleaning rollers 110a and 110b at the rotation speed S3, where S1 is the rotation speed of the cleaning roller 110b and S2 is the rotation speed of the cleaning roller 110b disposed on the downstream side. The photoconductor drums 1a and 110b are rotated at different rotational speeds by the cleaning unit.
0 is rotated in the same direction as the rotation direction.

As described with reference to FIGS. 2 and 7,
The rotation speed of the cleaning rollers 110a and 110b and the rotation speed of the photosensitive drum 10 are provided with a speed difference, and the cleaning rollers 110a and 110b are shifted from the photosensitive drum 10 to be forcibly driven to rotate so that the transfer residual toner on the photosensitive drum 10 is applied. The adhesive force is weakened mechanically to facilitate the movement of the toner. Cleaning roller 11 for photosensitive drum 10
The speed difference between 0a and 110b is preferably 1 to 10%.

That is, when the rotation speed of the photosensitive drum 10 is S,
Assuming that the rotation speed of the cleaning roller 110a disposed on the upstream side in the rotation direction of the photosensitive drum 10 is S1, and the rotation speed of the cleaning roller 110b disposed on the downstream side in the rotation direction of the photosensitive drum 10 is S2, 0.90 ≦ | (S
1−S) /S|≦0.99, 0.90 ≦ | (S2-S)
/S|≦0.99, and the cleaning roller 110
If the speed difference between the photosensitive drums 10a and 110b is less than 1%, the effect of weakening the adhesive force is not sufficient, and if it exceeds 10%, the speed difference is too large, and
Toner filming and toner scattering occur.

Further, it is preferable that the rotation speed of one of the rollers is higher and the rotation speed of the other roller is lower than the rotation speed of the photosensitive drum 10, and particularly, it is arranged upstream of the rotation direction of the photosensitive drum 10. The rotation speed S1 of the cleaning roller 110a is higher than the rotation speed S of the photosensitive drum 10, and the rotation speed S2 of the cleaning roller 110b disposed on the downstream side in the rotation direction of the photosensitive drum 10.
Is preferably smaller than the rotation speed S of the photosensitive drum 10 (S2 ≦ S ≦ S1). Cleaning roller 110 arranged upstream at a higher speed than photoconductor drum 10
a, the untransferred toner is extruded downstream, and the untransferred toner is extruded upstream by a cleaning roller 110 b arranged at a lower speed than the photosensitive drum 10, and the toner moves back and forth on the photosensitive drum 10. It is displaced in the direction, making recovery easier.

By bringing a plurality of cleaning means into contact with the image forming body at different rotational speeds, the toner is easily moved, so that toner collection and toner discharge by the cleaning means are facilitated. Further, by reducing the speed difference between the cleaning means and the image forming body and slowly rubbing the image forming body with the cleaning means, the transfer residual toner on the image forming body is rubbed in the moving direction of the image forming body, The mechanical adhesion to the image forming body is shifted,
The toner is easy to move, making recovery easier.

Further, by increasing or decreasing the rotation speed of the plurality of cleaning means with respect to the rotation speed of the image forming body, a different force is applied to the toner, and the adhesion of the toner to the image forming body and the cleaning means And the toner is easily collected and discharged by the cleaning means. Particularly, the transfer residual toner is extruded to the downstream side by the cleaning means arranged at a higher speed than the image forming body, and the transfer residual toner is moved to the upstream side by the cleaning means arranged at a lower speed than the image forming body. The toner is extruded, and the toner moves on the image forming body in the front-rear direction, thereby facilitating the recovery. In particular, the rotation speed S1 of the cleaning unit disposed on the upstream side in the rotation direction of the image forming body is reduced. The rotation speed S is higher than the rotation speed S, so that the toner is entangled in the cleaning device, so that the inside of the device due to the toner falling down is prevented, and the cleaning device disposed on the downstream side in the rotation direction of the image forming body. Is smaller than the rotation speed S of the image forming body, the toner is drawn out to the upstream side of the image forming body. To prevent contamination of the charging means by the toner release.

The speed difference between the cleaning rollers 110a and 110b with respect to the support roller 110c is also 1 to 1.
If the rotation speed of the support roller 110c is S3, the rotation speed of the photosensitive drum 10 is substantially equal to the rotation speed of the support roller 110c.
0.90 ≦ | (S1−S3) /S3|≦0.99, 0.
It is preferable that 90 ≦ | (S2−S3) /S3|≦0.99. Further, the rotation speed S3 of the support roller 110c is higher than the rotation speed of one of the cleaning units,
It is preferable that the rotation speed is lower than the rotation speed of the other cleaning unit.

When the plurality of cleaning means contact the support roller at different rotational speeds, the toner is easily moved, and the toner recovery and the toner discharge by the support roller and the cleaning means are facilitated.
Further, by reducing the speed difference between the cleaning means and the support roller and slowly rubbing the cleaning means with the support roller, the toner on the cleaning means is rubbed in the direction of movement of the support roller, and the mechanical adhesion to the cleaning means is reduced. The toner is weakened and displaced on the cleaning means, so that the toner is easily moved and the collection is made easier. In particular, by increasing or decreasing the rotation speed of the plurality of cleaning units with respect to the rotation speed of the support roller, a different force is applied to the toner, and the adhesion between the toner and the cleaning unit and the adhesion between the toner and the support roller are increased. To facilitate toner collection by the support roller and discharge of toner to the cleaning unit.

At the time of toner recovery or toner discharge, cleaning rollers 110a and 110 as cleaning means are provided.
As in the second example, different cleaning biases E2 and E3 for the cleaning roller are applied to the cleaning roller 0b as in the second example. A cleaning bias E4 is applied.

At the time of collecting the toner, the upstream cleaning roller 110a as the cleaning means is connected to the cleaning bias E2 for the cleaning roller as the cleaning bias for the cleaning means. A toner collection bias having a value V11 having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the cleaning roller 110a, and the transfer residual toner having a negative polarity on the photosensitive drum 10 is removed from the cleaning roller 110a.
The cleaning roller 110b on the downstream side as a cleaning means is connected to a cleaning bias E3 for a cleaning roller as a cleaning bias for the cleaning means.
Is applied to the cleaning roller 110 b, and the transfer residual toner of the negative polarity on the photosensitive drum 10 is removed from the cleaning roller 1.
It is collected on the outer peripheral surface of 10a. Further, it is connected to the cleaning bias E4 for the cleaning roller as the cleaning bias for the cleaning means, and has a value of the opposite polarity (positive polarity in this embodiment) to the toner indicated by the solid line in FIG. The cleaning roller 1 is driven by the support roller 110c to which the toner collection bias of V15 is applied.
The negative polarity toner on 10a and 110b is collected on the outer peripheral surface of support roller 110c. In order to completely recover the transfer residual toner in the transfer residual toner region, the toner recovery bias application region is formed to be slightly longer on both sides than the image forming region.

The potential level of the photosensitive drum 10 is reduced to substantially zero by the light neutralization of the light neutralizer 16, and the electrostatic attraction of the transfer residual toner to the photosensitive drum 10 is weakened, so that the transfer residual toner is easily moved. Further, the transfer to the cleaning rollers 110a and 110b to which the toner collection bias of the opposite polarity (positive polarity) V11 and V12 of the toner of the transfer residual toner is applied is facilitated, and the collection efficiency is improved.

Next, in the non-image forming area between the image forming areas after passing through the transfer residual toner area, the support roller 11
The cleaning bias E4 for the cleaning roller applied to 0c is a value V1 to which the same polarity (minus polarity in this embodiment) as the toner indicated by the dotted line in FIG. 8 is applied.
6. The support roller 110 is switched to the toner discharge bias of No. 6.
The collected toner (adhered toner) on c is discharged onto the cleaning rollers 110a and 110b. Further, the cleaning biases E2 and E3 for the cleaning rollers applied to the cleaning rollers 110a and 110b are set to the values V13 and V14 to which the same polarity (in the present embodiment, the negative polarity) is applied as the toner indicated by the dotted line in FIG. Switching to toner discharge bias
a, and the discharged toner (adhered toner) on 110b is discharged (adhered) onto the photosensitive drum 10. At this time, as shown in FIG. 3, the toner discharge bias application area from the start of the application of the toner discharge bias to the cleaning roller 110a to the stop of the application of the toner discharge bias to the cleaning roller 110b is applied to the toner collection bias to the cleaning roller 110a. The interval between the toner collection bias application areas from the start to the stop of the application of the toner collection bias of the cleaning roller 110b is set to be slightly shorter than the interval between the image forming areas (non-image forming area), and is set on the cleaning rollers 110a and 110b. All of the collected toner is discharged (adhered) onto the photosensitive drum 10. At this time, the photosensitive drum 10 is further subjected to light neutralization by the light neutralizer 16. The potential level of the photosensitive drum 10 is reduced to substantially zero by the light elimination, thereby facilitating the adhesion of the discharged toner to the photosensitive drum 10.

In the above-mentioned toner collection or toner discharge, at the time of toner collection, the cleaning section of the cleaning means applies a cleaning roller cleaning bias applied to the cleaning roller 110a disposed on the upstream side in the rotation direction of the photosensitive drum 10. The value V11 of the toner collecting bias of the cleaning roller E3 applied to the cleaning roller 110b disposed on the downstream side is set to the value V1 of the toner collecting bias of the cleaning roller E3.
2, the transfer residual toner that could not be recovered on the upstream side is recovered by a high toner recovery bias applied to the downstream cleaning means without recovering a large amount of toner at one time. The value V15 of the toner collection bias of the roller 110c is
b, which is larger than the toner collection bias value V12, so that the toner can be easily moved, and the cleaning rollers 110a, 1
10b facilitates toner collection to the support roller 110c.

At the time of discharging the toner, the cleaning unit changes the toner discharge bias value V13 of the cleaning roller cleaning bias E2 applied to the cleaning roller 110a disposed on the upstream side in the rotation direction of the photosensitive drum 10 to the downstream. The cleaning roller cleaning bias E3 applied to the cleaning roller 110b disposed on the side is set to be lower than the toner discharge bias value V14, and the voltage applied to the downstream cleaning means is set higher than the upstream side so that the upstream side has a higher voltage. To facilitate the discharge of the toner on the downstream side onto the discharged toner layer. Further, the toner discharge bias value V16 of the support roller 110c is used.
Is larger than the toner discharge bias value V13 of the cleaning roller 110b so that the toner can be easily moved.
a, 110b to facilitate discharge of toner.

As described above, the toner recovery ability of the cleaning means is improved by the support roller. In particular, good recovery is possible even when a small-diameter roller is used as the cleaning means or in a high-speed printer with a high rotation speed of the image forming body. Becomes Also, by increasing or decreasing the rotation speed of the plurality of cleaning means with respect to the rotation speed of the support roller, a different force is applied to the toner, thereby weakening the adhesion of the toner to the cleaning means, and collecting the toner by the support roller. To make it easier.

In the above example, the cleaning rollers 110a and 110b as cleaning means include:
A member having the same structure as that described with reference to FIGS. 5 and 6 is used.

A fourth example of toner collection and discharge by a plurality of cleaning means will be described with reference to FIGS. 9 and 3. FIG. 9 is a diagram illustrating a fourth example of toner collection and discharge by a plurality of cleaning units. This example is a method of collecting the opposite polarity toner contained in the transfer residual toner at the time of collecting the toner. This reverse polarity toner may be originally mixed in the developer, but also occurs when corona transfer is performed during transfer or when AC charge is removed from the image forming body by corona. In order to recover the toner of the opposite polarity, it is necessary to collect the roller with a bias having a polarity opposite to that of the toner.

The toner remaining in the untransferred toner area on the peripheral surface of the photoreceptor drum 10 after the transfer of the image forming area where the toner image is to be formed is removed by the light erasing device 16 as the erasing means.
And the potential level of the photosensitive drum 10 is reduced to substantially zero, and then the cleaning device 100b is reached.

The cleaning device 100b is provided in the cleaning casing 110d,
The cleaning unit includes two roller-shaped cleaning units that rotate in the same direction as the rotation direction of the photosensitive drum 10 in the cleaning unit. In the cleaning section, an upstream cleaning roller 110a as a cleaning unit is disposed on the upstream side in the rotation direction of the photoconductor drum 10, and a downstream cleaning roller 110b as a cleaning unit is disposed on the downstream side in the rotation direction of the photoconductor drum 10. Is done. The outer diameter of the upstream cleaning roller 110a is set smaller than the outer diameter of the downstream cleaning roller 110b. A cleaning device 210 for collecting the opposite polarity toner is disposed to face the cleaning roller 110b on the downstream side. The cleaning device 210 for collecting the reverse polarity toner rotates about the rotation support shaft 212 as a fulcrum, and abuts on the cleaning roller 110b. And a blade 211 capable of releasing the contact. The blade 211 is normally released from contact with the cleaning roller 110b, and is brought into contact with the cleaning roller 110b only when discharging toner, which will be described later.

As in the first example described with reference to FIG.
With respect to the photoconductor drum 10 rotated at the rotation speed S, the cleaning unit 110 sets the rotation speed of the cleaning roller 110a disposed on the upstream side in the rotation direction of the photoconductor drum 10 in the cleaning unit to the cleaning roller 110b disposed on the downstream side.
The rotation speed of the cleaning roller 110 is S2.
a, 110b, the cleaning rollers 110a,
The cleaning rollers 110a and 11b are forcibly driven by a gear G coupled to a gear (not shown) having the same diameter as that of the cleaning rollers 110a and 110b.
0b is rotated at a different rotation speed in the same direction as the rotation direction of the photosensitive drum 10 by the cleaning unit.

A rotation speed difference between the rotation speeds of the cleaning rollers 110a and 110b and the rotation speed of the photosensitive drum 10 is provided, and the cleaning rollers 110a and 110b are deviated from the photosensitive drum 10 to be forcibly driven to rotate.
The adhesion of the transfer residual toner is mechanically weakened to facilitate the movement of the toner. The speed difference between the cleaning rollers 110a and 110b with respect to the photosensitive drum 10 is 1 to 10
% Is preferred. That is, the rotation speed of the photoconductor drum 10 is S, the rotation speed of the cleaning roller 110a disposed on the upstream side in the rotation direction of the photoconductor drum 10 is S1, and the cleaning roller 110b is disposed on the downstream side in the rotation direction of the photoconductor drum 10. Assuming that the rotation speed of the motor is S2, 0.90 ≦ |
(S1-S) /S|≤0.99, 0.90≤ | (S2-
S) /S|≦0.99, and the cleaning roller 11
If the speed difference between the photosensitive drums 0a and 110b is less than 1%, the effect of weakening the adhesive force is not sufficient, and if it exceeds 10%, the speed difference is too large, and toner filming and toner scattering due to heat generation occur. .

It is preferable that the rotation speed of one of the rollers is higher and the rotation speed of the other roller is lower than the rotation speed of the photosensitive drum 10. The rotation speed S1 of the cleaning roller 110a is higher than the rotation speed S of the photosensitive drum 10, and the rotation speed S2 of the cleaning roller 110b disposed on the downstream side in the rotation direction of the photosensitive drum 10.
Is preferably smaller than the rotation speed S of the photosensitive drum 10 (S2 ≦ S ≦ S1). Cleaning roller 110 arranged upstream at a higher speed than photoconductor drum 10
a, the untransferred toner is extruded downstream, and the untransferred toner is extruded upstream by a cleaning roller 110 b arranged at a lower speed than the photosensitive drum 10, and the toner moves back and forth on the photosensitive drum 10. It is displaced in the direction, making recovery easier.

By bringing the plurality of cleaning means into contact with the image forming body at different rotational speeds, the toner is easily moved, and the toner collection and the toner discharge by the cleaning means are facilitated. Further, by reducing the speed difference between the cleaning means and the image forming body and slowly rubbing the image forming body with the cleaning means, the transfer residual toner on the image forming body is rubbed in the moving direction of the image forming body, The mechanical adhesion to the image forming body is shifted,
The toner is easy to move, making recovery easier.

Further, by increasing or decreasing the rotation speed of the plurality of cleaning means with respect to the rotation speed of the image forming body, a different force is applied to the toner so that the toner adheres to the image forming body and the cleaning means. And the toner is easily collected and discharged by the cleaning means. Particularly, the transfer residual toner is extruded to the downstream side by the cleaning means arranged at a higher speed than the image forming body, and the transfer residual toner is moved to the upstream side by the cleaning means arranged at a lower speed than the image forming body. The toner is extruded, and the toner moves on the image forming body in the front-rear direction, thereby facilitating the recovery. In particular, the rotation speed S1 of the cleaning unit disposed on the upstream side in the rotation direction of the image forming body is reduced. The rotation speed S is higher than the rotation speed S, so that the toner is entangled in the cleaning device, so that the inside of the device due to the toner falling down is prevented, and the cleaning device disposed on the downstream side in the rotation direction of the image forming body. Is smaller than the rotation speed S of the image forming body, the toner is drawn out to the upstream side of the image forming body. To prevent contamination of the charging means by the toner release.

The cleaning rollers 110a and 110b as two cleaning means are connected to different cleaning means cleaning biases. The cleaning roller 110b on the downstream side is connected to the cleaning bias E3 for the cleaning roller as the cleaning bias for the cleaning unit, as in the first to third examples, whereas the cleaning roller 110a on the upstream side is used as the cleaning bias for the cleaning unit. It is connected to the cleaning bias E5 for the cleaning roller.

At the time of collecting the toner, the cleaning roller 110a on the upstream side has the opposite polarity toner (positive polarity in this embodiment) and opposite polarity (positive polarity in this embodiment) indicated by the solid line in FIG. A reverse polarity toner collection bias of a value V21 of −300 to −1500 V (minus polarity) is applied, and the positive polarity toner included in the transfer residual toner on the photosensitive drum 10 is collected on the outer peripheral surface of the cleaning roller 110a. . The downstream-side cleaning roller 110b is connected to a cleaning roller cleaning bias E3 as a cleaning bias for the cleaning means as in the first to third examples. A toner collection bias of V12 of 300 to 1500 V having a polarity opposite to that of the transfer residual toner (positive polarity in the present embodiment) is applied to the cleaning roller 110b, and the negative transfer residual toner on the photosensitive drum 10 is applied. Is collected on the outer peripheral surface of the cleaning roller 110a. In order to completely recover the transfer residual toner in the transfer residual toner region, the toner recovery bias application region is formed to be slightly longer on both sides than the image forming region.

Next, the cleaning roller cleaning bias E3 applied to the cleaning roller 110b when the toner is discharged in the non-image forming area between the image forming areas after passing through the transfer residual toner area is indicated by a dotted line in FIG. V1 of a value of -300 to -1500 V to which the same polarity as the toner (minus polarity in the present embodiment) is applied
4, the collected toner on the cleaning roller 110b is discharged (adhered) onto the photosensitive drum 10. The cleaning bias E5 for the cleaning roller applied to the cleaning roller 110a is a floating line indicated by a dotted line in FIG. The bias is switched to the state of. At this time, the transfer residual toner of the negative polarity is applied to the cleaning roller 1 to which the bias of the positive polarity is applied.
After passing through 10a, it reaches the cleaning roller 110b.

In the above state, the blade 211 is brought into contact with the cleaning roller 110b, and the opposite polarity toner on the cleaning roller 110b is scraped off by the blade 211 and collected in the cleaning device 210 for collecting the opposite polarity toner. The recovery amount of the reverse polarity toner is as small as about several gr in 10,000 prints, and is replaced while being collected in the cleaning device 210 for reverse polarity toner recovery when the replacement life of the cleaning device 100b is 20,000 to 50,000. .

In the above, the cleaning roller 110b
When the toner is disposed downstream of the cleaning roller 110a, the opposite polarity toner adheres to the cleaning roller 110a when the toner is discharged, so that the opposite polarity toner cannot be collected.

In the above example, the cleaning rollers 110a and 110b as cleaning means include:
A member having the same structure as that described with reference to FIGS. 5 and 6 is used.

As described above, in addition to collecting and discharging the transfer residual toner on the image forming body, the reverse polarity toner mixed in the transfer residual toner can be collected well.

[0097]

According to the first aspect of the present invention, the plurality of cleaning means are brought into contact with the image forming body at different rotational speeds, so that the toner is easily moved, and the toner recovery and toner discharge by the cleaning means are facilitated. And let

According to the present invention, the residual toner on the image forming body moves by moving the image forming body by reducing the speed difference between the cleaning means and the image forming body and slowly rubbing the image forming body with the cleaning means. Direction, the mechanical adhesion to the image forming body is weakened, and the toner is displaced on the image forming body, so that the toner is easily moved and the collection is made easier.

According to the third to fifth aspects, the rotational speed of the plurality of cleaning means is increased or decreased with respect to the rotational speed of the image forming member, so that different forces are applied to the toner, and the toner image forming member is formed. And the adhesive force with the cleaning means is weakened, so that the toner can be easily collected and discharged by the cleaning means. Particularly, the transfer residual toner is extruded to the downstream side by the cleaning means arranged at a higher speed than the image forming body, and the transfer residual toner is moved to the upstream side by the cleaning means arranged at a lower speed than the image forming body. When the toner is extruded, the toner moves on the image forming body while being displaced in the front-rear direction, thereby making recovery easier.

In particular, according to the fourth aspect, the rotation speed S of the cleaning means disposed on the upstream side in the rotation direction of the image forming body.
By setting 1 to be higher than the rotation speed S of the image forming body, the toner is wound into the cleaning means, so that the inside of the apparatus due to the toner falling down is prevented.

In particular, according to the fifth aspect, the rotation speed S of the cleaning means disposed on the downstream side in the rotation direction of the image forming body.
By making 2 smaller than the rotation speed S of the image forming body, the toner is drawn out to the upstream side of the image forming body, thereby preventing the charging unit from being stained due to the discharge of the toner to the charging unit arranged further downstream.

According to the present invention, a plurality of cleaning means are applied with a cleaning bias for cleaning means for collecting or discharging toner having the same polarity and different values from each other, so that the cleaning means is brought into contact with the image forming member. In addition, the toner is easily moved, and the collection and discharge of the toner by the cleaning unit are facilitated. In particular, in the cleaning unit, the transfer residual toner on the image forming body is removed once by a cleaning unit arranged on the upstream side in the rotation direction of the image forming body, and further, the unremoved toner is arranged on the downstream side. It is completely removed by means. Further, by making the cleaning device cleaning bias of the cleaning device disposed on the downstream side in the rotation direction of the image forming member larger at the time of toner collection or toner discharge than the cleaning device cleaning bias of the cleaning device disposed on the upstream side, In particular, the toner not removed by the upstream cleaning means at the time of collection is removed by the downstream cleaning means, and also at the time of discharge, the toner from the downstream cleaning means is placed on the toner discharged by the upstream cleaning means. It is discharged well.

According to the ninth aspect, the toner collecting ability by the cleaning means is improved by the support roller.
In particular, good recovery is possible even when a small-diameter roller is used as the cleaning means or in a high-speed printer in which the rotation speed of the image forming body is high.

According to the tenth and eleventh aspects, the rotational speed of the plurality of cleaning means is increased or decreased with respect to the rotational speed of the support roller, so that different forces are applied to the toner. The adhesive force is weakened, and the toner is easily collected by the support roller.

According to the twelfth to fifteenth aspects, it is possible to collect the opposite polarity toner mixed in the transfer residual toner on the image forming body.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a laser printer showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating a first example of toner collection and discharge by a plurality of cleaning units.

FIG. 3 is a diagram illustrating an operation range of a cleaning bias for a cleaning unit.

FIG. 4 is a diagram illustrating a method of collecting transfer residual toner to a developing unit.

FIG. 5 is a side sectional view showing a first example of the structure of the cleaning unit.

FIG. 6 is a cross-sectional view showing second and third examples of the structure of the cleaning unit.

FIG. 7 is a diagram illustrating a second example of toner collection and discharge by a plurality of cleaning units.

FIG. 8 is a diagram illustrating a third example of toner collection and discharge by a plurality of cleaning units.

FIG. 9 is a diagram illustrating a fourth example of toner collection and discharge by a plurality of cleaning units.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 16 light eliminator 100, 100a, 100b cleaning device 110a, 110b cleaning roller 110c support roller 210 cleaning device E1, E2, E3, E4 for reverse polarity toner collection E5 Cleaning bias for cleaning roller

Claims (15)

[Claims] 1. A roller-shaped cleaning device that transfers untransferred toner adhering to a rotating image forming body in contact with the image forming body and rotates in the same direction as the image forming body at a contact portion with the image forming body. An image forming apparatus that once collects the toner and then discharges the toner onto the image forming body again. The image forming apparatus further includes a plurality of cleaning units to which a cleaning bias for a cleaning unit for toner collection or toner discharge is applied. An image forming apparatus having different rotation speeds and coming into contact with the image forming body. 2. The cleaning unit of the plurality of cleaning units, wherein the rotation speed of a cleaning unit arranged on the upstream side in the rotation direction of the image forming body is set to S1, and the rotation speed of the cleaning unit is arranged on the downstream side with respect to the rotation speed S of the image forming body. When the rotation speed of the cleaning means to be performed is S2, 0.90 ≦ | (S1-S) /S|≦0.99 0.90 ≦ | (S2-S) /S|≦0.99 The image forming apparatus according to claim 1, wherein: 3. The image forming apparatus according to claim 1, wherein one of the plurality of cleaning units has a rotation speed higher than the rotation speed of the image forming body, and the other rotation speed is lower than the rotation speed of the image forming body. An image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 1, wherein a rotation speed of the cleaning unit disposed upstream of the image forming body in the rotation direction is higher than a rotation speed of the image forming body.
The image forming apparatus according to claim 1. 5. The image forming apparatus according to claim 1, wherein a rotation speed of the cleaning unit disposed downstream of the image forming body is lower than a rotation speed of the image forming body.
The image forming apparatus according to claim 1. 6. A roller-shaped cleaning device for transferring untransferred toner adhering to a rotating image forming member, in contact with the image forming member and rotating in the same direction as the image forming member at a contact portion with the image forming member. A plurality of cleaning means provided in the image forming apparatus which once collects the toner and then discharges the toner onto the image forming body again; When the toner is collected, the cleaning unit of the plurality of cleaning units adjusts the value V11 of the cleaning unit cleaning bias applied to the cleaning unit disposed on the upstream side in the rotation direction of the image forming body. , A cleaning unit for cleaning means applied to a cleaning means disposed on the downstream side. An image forming apparatus, wherein the value is set to be lower than a value V12 of the ground. 7. When the toner is discharged, the cleaning unit of the plurality of cleaning units sets a cleaning unit cleaning bias value V13 applied to the cleaning unit disposed on the upstream side in the rotation direction of the image forming body, with the cleaning unit.
7. The image forming apparatus according to claim 6, wherein a value of a cleaning unit cleaning bias applied to the cleaning unit disposed downstream is set to be lower than a value V14. 8. V11 = (0.3-0.7) × (V1
8) The image forming apparatus according to claim 6, wherein V13 = (0.3 to 0.7) × (V14). 9. | V11 | = 300 to 1500 V, | V
13. The image forming apparatus according to claim 6, wherein 13 | = 300 to 1500 V. 10. A roller-shaped cleaning device for transferring untransferred toner adhering to a rotating image forming body in contact with the image forming body and rotating in the same direction as the image forming body at a contact portion with the image forming body. A plurality of cleaning means, and a support roller which rotates in contact with the plurality of cleaning means is provided, wherein the plurality of cleaning means are provided. An image forming apparatus, wherein the unit contacts the support roller at a rotation speed different from the rotation speed of the support roller. 11. The cleaning unit of the plurality of cleaning units, wherein the rotation speed of the cleaning unit arranged on the upstream side in the rotation direction of the image forming body is set to S1 and the downstream side is set to the rotation speed S3 of the support roller. Assuming that the rotation speed of the cleaning means is S2, 0.90 ≦ | (S1-S3) /S3|≦0.99 0.90 ≦ | (S2-S3) /S3|≦0.99 The image forming apparatus according to claim 10, wherein: 12. The rotation speed of the support roller is higher than the rotation speed of one of the plurality of cleaning means.
11. The rotation speed is lower than the other rotation speed.
Or the image forming apparatus according to 11. 13. A roller-shaped cleaning device for transferring untransferred toner adhering to a rotating image forming member, in contact with the image forming member and rotating in the same direction as the image forming member at a contact portion with the image forming member. A plurality of cleaning means provided in the image forming apparatus which once collects the toner and then discharges the toner onto the image forming body again; and when the toner is collected from the image forming body, the plurality of cleaning means have different polarities. An image forming apparatus, wherein a cleaning bias is applied. 14. When the toner is discharged to the image forming body, the cleaning units of the plurality of cleaning units perform
The cleaning unit cleaning bias applied to the cleaning unit disposed upstream in the rotation direction of the image forming body is set to a floating state, and the polarity of the cleaning unit cleaning bias applied to the cleaning unit disposed downstream is inverted. Claim 1 characterized by the following:
4. The image forming apparatus according to 3. 15. The image forming apparatus according to claim 13, wherein the cleaning unit of the plurality of cleaning units removes toner collected by a cleaning unit disposed upstream of the image forming body in the rotation direction. Image forming apparatus.