JP2002123091A - Toner scattering preventing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the trouble that toner scattering occurs in an intermediate transfer belt system. SOLUTION: This image forming device is equipped with a roller 3 arranged proximately to the rear surface of an intermediate transfer belt 102 on an opposite side to the surface thereof to which the toner image is transferred, and having an electromagnetic function turned on/off in specified timing by rotating in a reverse direction to the moving direction of the belt 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner scattering prevention device for an image forming apparatus for transferring a toner image from an image carrier to an intermediate transfer belt, and an image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art In an image forming apparatus employing an intermediate transfer belt system for transferring a toner image from an image carrier to an intermediate transfer belt, an image carrier, a developing device, a cleaning device,
When the intermediate transfer belt and the toner are replaced, there is a problem that the toner peels and drops due to a part of transfer failure or the like, and contaminates the inside of the apparatus as scattered toner.

[0003] Regarding such problems, mechanical and
As technology to electrically prevent toner scattering,
Japanese Patent Application Laid-Open No. 4-274263 discloses a technique for preventing toner scattering occurring on an image carrier. In this technique, a tray for receiving toner falling from an image carrier is provided, and the toner is moved in a direction away from the image carrier.

In Japanese Patent Application Laid-Open No. 4-126261, a toner guide plate is provided in an apparatus, and the material of the toner guide plate is made to have a property of being hardly triboelectrically charged.
A technique that has an effect of suppressing toner adhesion and scattering is described. Japanese Utility Model Application Laid-Open No. 2-98359 describes a technique for preventing toner scattering from a developing device.
JP-A-2-15289, JP-A-2-15290 and JP-A-2-27388 describe a technique for preventing toner from scattering from a cleaning device.

[0005] Further, a toner scattering prevention device used in an image forming apparatus of a system for transferring a toner image formed on an image carrier to a recording material via an intermediate transfer belt, for preventing toner scattering from the intermediate transfer belt. In the above, there has been proposed a toner scattering prevention device having a roller which is installed close to the back side of the surface of the intermediate transfer belt on which the toner image is transferred and which can rotate in the direction opposite to the moving direction of the intermediate transfer belt. ing.

[0006]

The above technique has the following problems. In recent years, image forming apparatuses employing an intermediate transfer belt system are becoming mainstream in order to reduce the problem of ozone generation due to discharge. In the apparatus employing the intermediate transfer belt system, not only toner scattering occurs at the contact portion between the image carrier and the developing device and the cleaning device, but also toner scattering at the contact portion between the image carrier and the intermediate transfer belt. In addition, the movement of the intermediate transfer belt causes scattering of the toner captured by the air boundary layer generated on the surface layer of the intermediate transfer belt, and these scattered toners are widely diffused inside the apparatus, resulting in malfunction of various sensors. Has occurred.

In the above prior art, only toner scattering at a contact portion between an image carrier, a developing device, and a cleaning device is prevented, and the problem of toner scattering in an image forming apparatus employing an intermediate transfer belt system, that is, However, the problem of scattering of the toner captured by the air boundary layer generated on the surface of the intermediate transfer belt due to the movement of the intermediate transfer belt cannot be solved. Further, in the toner scattering prevention device,
There is a problem that a sufficient dust collecting effect cannot be expected by the roller, and the toner that has not been collected is scattered inside the apparatus by the rotation of the roller.

According to the first aspect of the invention, it is possible to prevent the toner captured by the air boundary layer generated on the surface layer of the intermediate transfer belt by the movement of the intermediate transfer belt from scattering.
An object of the present invention is to provide a toner scattering prevention device which can easily and at low cost solve the problem of toner scattering in an image forming apparatus employing an intermediate transfer belt system. A second object of the present invention is to provide a toner scattering prevention device capable of realizing an effective layout for achieving the object of the first invention.

A third object of the present invention is to provide a toner scattering prevention apparatus which can reuse scattered toner from the viewpoint of recycling. An object of the invention according to claim 4 is to provide a toner scattering prevention device which can surely collect scattering toner. A fifth object of the present invention is to provide a toner scattering prevention device capable of suppressing a reduction in a toner scattering prevention effect that occurs under a condition in which the moving speed of the intermediate transfer belt is high.

It is another object of the present invention to provide a toner scattering preventing apparatus which can reduce the problem of toner accumulation which occurs in continuous operation for a long time. According to the ninth aspect of the present invention, the problem of toner scattering when the intermediate transfer belt system is adopted can be easily and inexpensively solved, and the air boundary layer generated on the surface of the intermediate transfer belt by the movement of the intermediate transfer belt can be used. An object of the present invention is to provide an image forming apparatus that can prevent scattering of captured toner.

[0011]

According to a first aspect of the present invention, there is provided a toner scattering prevention device for an image forming apparatus for transferring a toner image from an image carrier to an intermediate transfer belt. It has an electromagnet function that is arranged close to the back surface of the belt opposite to the surface on which the toner is transferred, and is turned on / off at a predetermined timing by rotating in a direction opposite to the moving direction of the intermediate transfer belt. It has a roller.

According to a second aspect of the present invention, in the toner scattering prevention device according to the first aspect, a part of the surface of the electromagnet roller enters an air boundary layer generated as the intermediate transfer belt moves. The electromagnet roller is provided. According to a third aspect of the present invention, in the toner scattering prevention device according to the first aspect, a toner dust box provided below the roller is provided.

According to a fourth aspect of the present invention, there is provided the toner scattering prevention device according to the third aspect, further comprising a case for sealing the roller and the toner dust box except for an upper surface of the roller. According to a fifth aspect of the present invention, in the toner scattering prevention device of the fourth aspect, an air vent is provided in the case so that the internal pressure and the external pressure of the case are equal.

According to a sixth aspect of the present invention, there is provided the toner scattering prevention apparatus according to the first aspect, further comprising a vibrating means for applying vibration to the roller. The invention according to claim 7 is
4. The toner scattering prevention device according to claim 3, wherein a predetermined inner surface of the toner dust box has a polarity opposite to a charging polarity of the toner on the image carrier.

According to an eighth aspect of the present invention, in the toner scattering prevention device of the third aspect, a vibration applying means for applying vibration to the toner dust box is provided. According to a ninth aspect of the present invention, there is provided the toner scattering prevention device according to any one of the first to eighth aspects.

[0016]

FIG. 2 shows a first embodiment of the present invention. The first embodiment is an embodiment of an image forming apparatus having a toner scattering prevention device, and in an image forming apparatus employing an intermediate transfer belt system, a side of the intermediate transfer belt opposite to a surface to which toner is transferred. Placed close to the back,
The image forming apparatus includes a toner scattering prevention device having a roller having an electromagnet function (hereinafter, referred to as an electromagnet roller) which rotates in a direction opposite to the direction of movement of the intermediate transfer belt and is turned on / off at a predetermined timing.

As shown in FIG. 2, for example, a drum-shaped photoreceptor 101 is used as a photoreceptor as an image carrier, and the photoreceptor 101 is driven to rotate in a direction indicated by an arrow by a driving unit (not shown). The photoreceptor 101 is uniformly charged by a charging unit (not shown) and then exposed by an exposure unit (not shown) to form an electrostatic latent image. The electrostatic latent image on the photoreceptor 101 is developed into a toner image by a developing unit 106 as a developing unit.
A toner image forming unit 6 forms a toner image on the photoconductor 101.

The toner image on the photosensitive member 101 is transferred to the transfer unit 10
At 0, the image is transferred to the intermediate transfer belt 102 by an intermediate transfer charger 103 as a transfer unit. The intermediate transfer belt 102 is stretched over a plurality of rollers 107 to 111 and comes into contact with the photoconductor 101.
The intermediate transfer belt 102 is rotated in the direction of the arrow at the same peripheral speed as the photoconductor 101 by rotating the driving roller out of 07 to 111.

A bias is applied to the back surface of the intermediate transfer belt 102 by the intermediate transfer charger 103 so that the photosensitive member 1
01 is applied with a potential having a polarity opposite to that of the toner on the intermediate transfer belt 1.
02 is transferred to the surface. The toner image on the intermediate transfer belt 102 is transferred to a sheet 105 as a transfer material fed from a sheet feeding device (not shown) by a transfer unit (not shown), and the sheet 105 is fixed by a fixing device (not shown) and discharged. You. The photoreceptor 101 is cleaned by a cleaning device (not shown) after transferring the toner image to remove the residual toner, and the intermediate transfer belt 102 is cleaned by a cleaning device having a cleaning blade 104 after the toner image is transferred onto the paper 105 to remove the residual toner. Is done.

In such an image forming operation, the toner 1 is adhered to the photosensitive member 101 by the developing unit 106. The toner 1 on the photoconductor 101 is transferred to the intermediate transfer charger 1
03, a bias is applied to the back surface of the intermediate transfer belt 102, and a potential having a polarity opposite to the charging polarity of the toner on the photoconductor 101 is given.
Is transferred to the surface of At this time, a part of the toner 1 becomes scattered toner 2 and is captured in an air boundary layer generated on the surface layer of the intermediate transfer belt 102 generated as the intermediate transfer belt 102 moves.

FIG. 1 shows a toner scattering prevention device according to the first embodiment. This toner scattering prevention device has an electromagnet roller 3, and the electromagnet roller 3 is
From the position where the toner image is transferred to the intermediate transfer belt 102 in the moving direction of the intermediate transfer belt 102, and the position upstream of the position where the toner image is transferred from the intermediate transfer belt 102 to the paper 105 in the moving direction of the intermediate transfer belt 102. Installed in The intermediate transfer belt 102 moves from left to right in FIG. 1, and the toner 1 is transferred from the photoconductor 101 to the surface. An air boundary where a part of the scattered toner 2 generated due to transfer failure at the contact portion between the photoconductor 101 and the intermediate transfer belt 102 is generated on the surface layer (air) of the intermediate transfer belt 102 as the intermediate transfer belt 102 moves. The air boundary layer moves with the intermediate transfer belt 102 while being captured by the layer.

The electromagnet roller 3 is disposed close to the back surface of the intermediate transfer belt 102 opposite to the surface on which the toner 1 is transferred, and rotates in a direction opposite to the moving direction of the intermediate transfer belt 102, The scattered toner 2 captured by the air boundary layer on the surface of the intermediate transfer belt 102 is captured by the air boundary layer generated by the electromagnet roller 3 and is separated from the air boundary layer on the surface of the intermediate transfer belt 102. Moreover, the scattered toner 2 is charged by the electromagnetic field generated by the electromagnet roller 3, is attracted to and comes into contact with the electromagnet roller 3, and adheres to the surface of the electromagnet roller 3.

It is desirable that the electromagnet roller 3 does not contact the intermediate transfer belt 102. This is to suppress the adverse effect on the image formation due to the vibration due to the rotation of the electromagnet roller 3. The electromagnet roller 3 and the intermediate transfer belt 102 are separated by a certain distance in the roller axis direction. Thereby, the phenomenon that the scattered toner 2 floats inside the apparatus due to the movement of the intermediate transfer belt 102 can be suppressed. Note that scraping off the scattered toner 2 captured by the surface air boundary layer of the intermediate transfer belt 102 with the electromagnet roller 3 may adversely affect the formed image, which may cause a problem. The electromagnet roller 3 is arbitrarily turned on / off by means for turning on / off the electromagnet function (electromagnetic field generation). When the electromagnet function is turned off, the electromagnet function does not generate an electromagnetic field and the scattered toner 2 attached to the surface falls by gravity. By doing so, it is easy to collect the scattered toner 2.

According to the first embodiment, the intermediate transfer belt 102 is disposed close to the rear surface of the intermediate transfer belt 102 opposite to the surface on which the toner 1 is transferred, and has a direction opposite to the moving direction of the intermediate transfer belt 102. And the roller 3 having an electromagnet function that is turned on and off at a predetermined timing by rotating the intermediate transfer belt, so that the toner caught by the air boundary layer generated on the surface of the intermediate transfer belt by the movement of the intermediate transfer belt is reliably captured. Thus, it is possible to easily and at low cost solve the problem of toner scattering in an image forming apparatus employing an intermediate transfer belt system. In addition, the scattered toner can be sent to another recycling process.

FIG. 3 shows a toner scattering prevention device according to a second embodiment of the present invention. In the second embodiment, the second
In the first embodiment, the electromagnet roller 3 is installed so that a part of the surface of the electromagnet roller 3 enters the air boundary layer 4 generated as the intermediate transfer belt 102 moves.

The thickness of the air boundary layer 4 generated with the movement of the intermediate transfer belt 102 is

[0027]

(Equation 1)

Is the distance h given by Here, x is the distance from the end of the intermediate transfer belt 102, v is the kinematic viscosity of air, and U is the moving speed of the intermediate transfer belt 102. In the second embodiment, the electromagnet roller 3 is arranged such that the surface (upper surface) of the electromagnet roller 3 is located at a position separated from the surface (lower surface) of the intermediate transfer belt 102 by a distance smaller than the distance h.

In general, when a planar object moves in the air in a direction parallel to the surface of the object, an air boundary layer represented by the distance h in the above equation is generated on the surface layer. Here, x is the distance from the end of the object, v is the kinematic viscosity of air, and U is the moving speed of the object. When the moving distance of the object is 0.01 m and the moving speed of the object is 1 m / s, the size of the air boundary layer generated is about 1
mm. The air boundary layer generated by the intermediate transfer belt 102 indicates an area affected by the movement of the intermediate transfer belt 102. At this time, it is desirable that the distance between the electromagnet roller 3 and the intermediate transfer belt 102 is not more than the thickness h of the air boundary layer generated by the intermediate transfer belt 102. This is because the toner 2 scattered by the intermediate transfer belt 102 is captured by the electromagnet roller 3 in the air boundary layer.

According to the second embodiment, in the first embodiment, a part of the surface of the electromagnet roller 3 is set so as to enter the air boundary layer 4 generated as the intermediate transfer belt 102 moves. Since the electromagnet roller 3 is provided, an effective layout for achieving the object of the first embodiment can be realized, and the apparatus becomes more compact.

FIG. 4 shows a toner scattering prevention device according to a third embodiment of the present invention. In the third embodiment, of the scattered toner 2 trapped in the air boundary layer generated on the surface of the intermediate transfer belt 102 in the first embodiment, the intermediate transfer belt 10 is rotated by the rotation of the electromagnet roller 3.
A toner dust box 5 is provided for receiving the toner that is separated from the air boundary layer of the two outer layers and falls below the electromagnet roller 3.

In general, the electromagnet roller 3 is not energized when not in operation, and the electromagnet function is turned off. In such a case, the scattered toner 2 captured and adhered on the electromagnet roller 3 drops due to the effect of gravity. A toner dust box 5 is provided immediately below the electromagnet roller 3, and the scattered toner 2 dropped from the electromagnet roller 3 is received by the toner dust box 5 and collected.

According to the third embodiment, since the toner dust box 5 provided below the electromagnet roller 3 is provided, the scattered toner 2 caught by the electromagnet roller 3 during operation is collected when the toner is not operated. By being collected in the dust box 5,
The scattered toner 2 can be reused.

FIG. 5 shows a toner scattering prevention device according to a fourth embodiment of the present invention. In the fourth embodiment, in the third embodiment, the toner scattering prevention device is configured such that the electromagnet roller 3 and the toner dust box 5 are sealed (shielded) by the case 6 except for the upper surfaces thereof. It is. Therefore, of the scattered toner 2 scraped off by the electromagnet roller 3 from the air boundary layer 4 generated by the movement of the intermediate transfer belt 102 and the scattered toner 2 dropped from the electromagnet roller 3, the dust is collected in the toner dust box 5. The scattered toner 2 that has not been scattered does not scatter to the outside of the case 6, but is eventually captured by the air boundary layer generated by the movement of the electromagnet roller 3 and collected in the toner dust box 5, so that it is surely collected. Captured by

As described above, according to the fourth embodiment, since the case 6 for sealing the electromagnet roller 3 and the toner dust box 5 except for the upper surface of the electromagnet roller 3 is provided, the scattered toner is reliably collected. can do.

FIG. 6 shows a toner scattering prevention device according to a fifth embodiment of the present invention. In the fifth embodiment, in the fourth embodiment, the toner scattering prevention device is
Fine air vent 7 so that the internal pressure of the air becomes the same as the atmospheric pressure
Is provided at the lower part of the case 6. Therefore, the internal pressure of the case 6 is always equal to the atmospheric pressure. Thereby, it occurs when the moving speed of the intermediate transfer belt 102 is extremely high.
It is possible to avoid the problem that the internal pressure in the case 6 is increased and the scattered toner 2 is not properly collected in the toner collection box 5.

As described above, according to the fifth embodiment, since the air vent 7 is provided in the case 6 so that the internal pressure and the external pressure of the case 6 become the same, the condition that the moving speed of the intermediate transfer belt is high can be obtained. Can be prevented from being reduced in the toner scattering prevention effect.

FIG. 7 shows a toner scattering prevention device according to a sixth embodiment of the present invention. In the sixth embodiment, the toner scattering prevention device according to the first embodiment is different from that of the first embodiment in that
Is provided with a piezoelectric element 8 disposed in contact with the piezoelectric element 8. The piezoelectric elements 8 are installed at both ends of the shaft of the electromagnet roller 3 so as not to hinder the rotation of the electromagnet roller 3.

The piezoelectric element 8 is provided so as to be capable of coming into contact with and separating from the electromagnet roller 3. The piezoelectric element 8 is brought into contact with the electromagnet roller 3 only by non-operation by means of an unillustrated separation / separation means to apply vibration to the electromagnet roller 3. It is desirable to have a structure separated from the electromagnet roller 3 by means. By applying vibration to the electromagnet roller 3 from the piezoelectric element 8, the electromagnet roller 3
It is possible to drop the scattered toner 2 attached to the surface of the device from the electromagnet roller 3. Accordingly, excessive scattering toner 2 on the surface of the electromagnet roller 3, which is a problem that occurs when the toner scattering prevention device is operated for a long time,
It is possible to suppress the toner scattering prevention effect from being reduced due to the accumulation of the toner, and to maintain the toner scattering prevention effect for a long time.

As described above, according to the sixth embodiment, the piezoelectric element 8 as a vibration means for applying vibration to the electromagnet roller 3 is used.
The electromagnetic roller 3
Can be reduced.

FIG. 8 shows a toner scattering prevention device according to a seventh embodiment of the present invention. In the seventh embodiment, in the third embodiment, the toner scattering prevention device is different from the third embodiment in that, for example, the bottom surface of the inner surface of the toner dust box 5 has a polarity opposite to the charging polarity of the toner on the photoconductor 101. Is what it is.
In this case, the toner on the photoconductor 101 is negatively charged, and the inner surface of the toner dust box 5 is positively charged.
As a result, the scattered toner 2 is easily attracted to the toner dust box 5, and the scattered toner 2 can be more effectively collected.

As described above, according to the seventh embodiment, the predetermined inner surface of the toner dust box 5 is provided with the photosensitive member 10 as an image carrier.
Since the toner has a polarity opposite to the charging polarity of the toner, the scattering toner can be collected more effectively, and the problem of toner accumulation occurring in the electromagnet roller during continuous operation for a long time can be reduced. .

FIG. 9 shows a toner scattering prevention device according to an eighth embodiment of the present invention. In the eighth embodiment, in the third embodiment, the toner scattering prevention device is provided with a piezoelectric element 9 as a vibration means for applying vibration to the toner dust box 5. The piezoelectric element 9 can arbitrarily apply vibration to the toner dust box 5 by contacting the lower surface of the toner dust box 5. When vibration is applied from the piezoelectric element 9 to the toner dust box 5, the toner dust box 5
The scattered toner 2 inside is well collected so that the upper surface is substantially flat.

As a result, it is possible to suppress a decrease in the toner scattering prevention effect due to excessive accumulation of the scattering toner 2 on the surface of the toner dust box 5, which is a problem that occurs when the toner scattering preventing device is operated for a long time. The effect of preventing toner scattering for a long time can be maintained. Further, the toner recycling effect is also increased. As described above, according to the eighth embodiment, the piezoelectric element 9 as a vibrating means for applying vibration to the toner dust box 5 is provided.
Is provided, it is possible to reduce the problem of toner accumulation that occurs in the case of continuous operation for a long time.

[0045]

As described above, according to the first aspect of the present invention, it is possible to prevent the toner trapped by the air boundary layer generated on the surface layer of the intermediate transfer belt by the movement of the intermediate transfer belt from scattering. The problem of toner scattering in an image forming apparatus employing the transfer belt method can be easily and inexpensively solved. According to the second aspect of the present invention, an effective layout can be realized to achieve the object of the first aspect of the present invention.

According to the third aspect of the invention, the scattered toner can be reused from the viewpoint of recycling.
According to the fourth aspect of the present invention, it is possible to reliably collect the scattered toner. According to the fifth aspect of the invention, it is possible to suppress a reduction in the toner scattering prevention effect that occurs under the condition that the moving speed of the intermediate transfer belt is high.

According to the sixth to eighth aspects of the present invention, it is possible to reduce the problem of toner accumulation that occurs during long-time continuous operation. According to the ninth aspect of the present invention, the problem of toner scattering when the intermediate transfer belt system is adopted can be easily and inexpensively solved, and the boundary of the air generated on the surface of the intermediate transfer belt due to the movement of the intermediate transfer belt. The scattering of the toner captured by the layer can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a toner scattering prevention device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the whole of the first embodiment.

FIG. 3 is a cross-sectional view illustrating a toner scattering prevention device according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a toner scattering prevention device according to a third embodiment of the present invention.

FIG. 5 is a sectional view illustrating a toner scattering prevention device according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing a toner scattering prevention device according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view showing a toner scattering prevention device according to a sixth embodiment of the present invention.

FIG. 8 is a sectional view showing a toner scattering prevention device according to a seventh embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating a toner scattering prevention device according to an eighth embodiment of the present invention.

[Explanation of symbols]

 102 Intermediate transfer belt 3 Electromagnet roller 5 Toner dust box 6 Case 7 Air vent 8, 9 Piezoelectric element

Claims (9)

[Claims] An image forming apparatus for transferring a toner image from an image bearing member to an intermediate transfer belt, wherein the intermediate transfer belt is disposed close to a back surface opposite to a surface on which toner is transferred. And a roller having an electromagnet function that rotates in a direction opposite to the moving direction of the intermediate transfer belt and is turned on / off at a predetermined timing. 2. The toner scattering prevention device according to claim 1, wherein the electromagnet roller is disposed such that a part of the surface of the electromagnet roller enters an air boundary layer generated as the intermediate transfer belt moves. A toner scattering prevention device characterized by the above-mentioned. 3. The toner scattering prevention device according to claim 1, further comprising a toner dust box provided below said roller. 4. The toner scattering prevention device according to claim 3, further comprising a case for sealing the roller and the toner dust box except for an upper surface of the roller. 5. The toner scattering prevention device according to claim 4, wherein an air vent is provided in the case so that the internal pressure and the external pressure of the case become equal. 6. The toner scattering prevention device according to claim 1, further comprising a vibrating means for applying vibration to said roller. 7. The toner scattering prevention device according to claim 3, wherein a predetermined inner surface of the toner dust box has a polarity opposite to a charging polarity of the toner on the image carrier. Toner scattering prevention device. 8. The toner scattering prevention device according to claim 3, further comprising a vibrating means for applying vibration to the toner dust box. 9. An image forming apparatus comprising the toner scattering prevention device according to claim 1.