JPH09330003A - Cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device by which much more toner on a cleaning roller is removed and whose toner removing performance is improved. SOLUTION: This cleaning device is equipped with the cleaning roller 23 which is rotated while being pressed to a photo-receptor 1 and triboelectrifies the toner left after transfer where positive and negative polarities coexist so as to make its polarity the same as the toner after developing, whereby the toner on the photoreceptor may be removed; bias rollers 24 and 26 rotating in contact with the roller 23 and removing the toner on the roller 23; a means 30 for impressing specified voltage on the rollers 23, and 24 and 26; and scraping members 25 and 27 removing the toner on the rollers 24 and 26. In such a case, two bias rollers 24 and 26 are provided and further the voltage having the positive polarity and negative polarity is impressed on two rollers 24 and 26. Thus, the toner having the different polarities on the roller 23 is selectively recovered by the rollers 24 and 26, and the toner removing performance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to a cleaning roller for cleaning transfer residual toner on an image carrier such as a photoconductor. The present invention relates to a cleaning device of the type that is removed by.

[0002]

2. Description of the Related Art In a cleaning device used in an electrophotographic image forming apparatus such as a copying machine, a printer or a facsimile, a cleaning device of a type that removes transfer residual toner on an image bearing member such as a photoconductor with a cleaning roller is known. Are known. For example, in Japanese Patent Laid-Open No. 60-57879, an elastic roller that rotates while being pressed against the surface of a recording medium to remove toner and a core metal of the elastic roller that rotates while making contact with the elastic roller are disclosed. A bias roller to which a voltage is applied, and a member for removing toner from the peripheral surface of the bias roller. The voltage applies an electric field of polarity and strength with which the charged toner is attracted to the bias roller. There is disclosed a cleaning device characterized by being set and by positively charging the toner by a precharger. Further, Japanese Patent Laid-Open No. 62-67578 discloses a cleaning device which removes toner remaining on a recording medium by means of a sponge roller provided so as to slide on the recording medium, facing the sponge roller. , A collecting roller made of metal or semiconductor that holds a slight gap or a weak contact state, a power supply for supplying a DC bias voltage having a polarity opposite to the charging polarity of toner to the collecting roller, and cleaning the collecting roller. There is disclosed a cleaning device having means for collecting toner.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the cleaning device disclosed in Japanese Patent Laid-Open No. 57879, when the transfer residual toner is removed from the photosensitive member by the elastic roller and the toner on the elastic roller is attracted to the bias roller by providing an electric field between the elastic roller and the bias roller. , The toner on the elastic roller after passing through the bias roller without being completely adsorbed may adhere to the photoconductor again when it encounters the photoconductor again, and it is carried to the charging section and the charging roller is soiled. . Further, since the transfer residual toner is charged to one polarity by the precharger prior to cleaning, there is a problem that ozone is generated and the environment is adversely affected.

Further, in the cleaning device described in Japanese Patent Laid-Open No. 62-67578, when the transfer residual toner is removed from the photosensitive member by the sponge roller, all the transfer residual toner is triboelectrically charged and the toner polarity after development is increased. Is not
It is electrically and mechanically transferred onto the sponge roller. Then, since the toner on the sponge roller is collected by the collecting roller, when a DC voltage having a polarity opposite to that of the toner after development is applied and electrically attracted, the toner having the other polarity remains on the sponge roller. In this state, when the recovered residual toner encounters the photoconductor again, the remaining toner of the opposite polarity is transferred to the photoconductor, and is carried to the charging section, thus contaminating the charging roller.

The present invention has been made to solve the above-mentioned drawbacks of the prior art. When the toner collected on the cleaning roller encounters the photoconductor again without the generation of ozone, the photoconductor is regenerated. An object of the present invention is to provide a cleaning device having improved toner removal performance, which can eliminate problems such as dirt on the charging roller without sticking to the charging roller.
And

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 rotates while being pressed by an endless image carrier, and a transfer residue in which positive (+) and negative (-) polarities are mixed. A cleaning roller composed of a conductive member that removes toner on the image carrier by frictionally charging the toner to make it polar after development, and a voltage is applied to the cleaning roller to clean the toner on the image carrier. A means for forming an electric field toward the roller, a bias roller for rotating in contact with the cleaning roller to remove toner on the cleaning roller, and a voltage for transferring the toner on the cleaning roller to the bias roller. A cleaning device comprising means for applying to the bias roller and a scraping member for removing the toner on the bias roller. Te, in which the bias roller which rotates in contact with the cleaning roller and two provided comprising configuration. That is, in the cleaning device according to the first aspect, since two bias rollers that rotate in contact with the cleaning roller are provided, the toner on the cleaning roller is collected by the bias roller on the upstream side in the rotation direction of the cleaning roller, The toner that cannot be completely collected can be collected by the bias roller on the downstream side.

According to a second aspect of the present invention, in the cleaning apparatus according to the first aspect, the applied voltages to the two bias rollers are "+ polarity" and "-polarity". That is, in the cleaning device according to claim 2, since the voltages of "+ polarity" and "-polarity" are applied to each of the two bias rollers provided, the cleaning roller is composed of two bias rollers. The toners having different polarities can be selectively collected.

According to a third aspect of the present invention, in the cleaning device according to the first aspect, the voltage applied to the two bias rollers has a polarity opposite to that of the toner after development from the upstream side in the rotation direction of the cleaning rollers. , And then “having the same polarity as the toner after development”. That is, in the cleaning device according to the third aspect, the voltage applied to the two bias rollers is “reverse polarity to the toner after development (for example, + polarity)” from the upstream side in the rotation direction of the cleaning roller, and then “development”. Since the toner has the same polarity (for example, −polarity) as the post-toner, “the toner having the opposite polarity (+ polarity) after the development” contained in the large amount of toner on the cleaning roller has almost all the toner amount after removal. Almost all "-polarity toner" is collected by the downstream side bias roller from the amount after the upstream side bias roller collects more than half, so almost all "developed toner and reverse polarity (+ polarity) toner" Can be collected.

According to a fourth aspect of the present invention, in the cleaning device according to the first aspect, among the two bias rollers provided, the applied voltage to the bias roller provided on the upstream side in the rotation direction of the cleaning roller is " The toner having the same polarity as the toner after development has a voltage such that an electric field directed to the bias roller is generated. Further, in the invention of claim 5, the cleaning is performed among the two bias rollers provided. The voltage applied to the bias roller provided on the downstream side in the rotational direction of the roller is characterized by a voltage such that an electric field of "toner having a polarity opposite to that of the toner after development" is generated toward the bias roller. That is, in the cleaning device according to the fourth aspect, the applied voltage of the bias roller provided on the upstream side in the rotation direction of the cleaning roller is “toner having the same polarity as the toner after development”.
The toner having the same polarity as the toner after development can be recovered from the toner on the cleaning roller, since the voltage is such that an electric field is generated toward the bias roller.
In the cleaning device described above, the voltage applied to the bias roller provided on the downstream side in the rotation direction of the cleaning roller is such a voltage that "a toner having a polarity opposite to that of the toner after development" causes an electric field toward the bias roller. It is possible to collect the toner remaining on the cleaning roller and having a polarity opposite to that of the toner after development. Therefore, according to the constitutions of claims 4 and 5, almost all the toner on the cleaning roller can be collected.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a schematic configuration diagram of a printer (or a printer section of a copying machine or a facsimile) showing an example of an image forming apparatus equipped with the cleaning device of the present invention. Reference numeral 1 in the figure is an image carrier. A certain photosensitive drum, 2 is a charging roller for charging the photosensitive drum 1, 3 is a power source for a charging roller for applying a predetermined voltage to the charging roller 2, 4 is a laser light source, an optical deflector, and imaging optics. Laser light from an optical writing device for forming an electrostatic latent image by optical writing on the photosensitive drum, which is composed of a system and the like, 5 is a developing roller of a developing device for developing the electrostatic latent image on the photosensitive drum,
Reference numerals 6 and 7 denote a left screw and a right screw for conveying and stirring the developer, 8 a doctor for regulating the amount of the developer on the developing roller, 9 and 10 a lower case and an upper case of the developing device, and 11 a developing roller 5 A developing roller power source for applying a predetermined developing bias voltage to the developing roller, and 12 and 13 are transfer sheets 16 fed from a sheet feeding unit (not shown) through a sheet feeding mechanism at a predetermined timing with toner on the photosensitive drum. Upper registration rollers and lower registration rollers that convey the image to the image transfer position, and 14 and 15 are an upper guide plate, a lower guide plate, and a lower guide plate that are installed in the transfer sheet conveyance path.
Reference numeral 7 denotes a transfer roller which is arranged at the toner image transfer position so as to face the photoconductor drum 1 and transfers the toner image on the photoconductor drum 16 onto the transfer paper 16, and 18 applies a predetermined transfer bias voltage to the transfer roller 17. Is a power source for the transfer roller, 19 is a paper discharging needle for discharging the transfer paper 16 to separate the transfer paper 16 after the toner image transfer from the photosensitive drum 1, and 20 is a predetermined voltage applied to the paper discharging needle 19. Power sources 21 and 22 for removing paper from paper are rollers and a paper transport belt for transporting the transfer paper 16 separated from the photosensitive drum 1 to a fixing device (not shown).

Further, reference numerals 23 to 30 in the drawing are constituent members of the cleaning device according to the present invention, and 23 is for rotating while being pressed by the photosensitive drum 1 to remove transfer residual toner on the photosensitive drum. Cleaning roller made of a conductive member, 24 is a lower bias roller that rotates in contact with the cleaning roller 23 to remove the toner on the cleaning roller 23, 25 is a lower bias blade that scrapes and removes the toner on the lower bias roller 24, 26 is an upper bias roller that rotates in contact with the cleaning roller 23 to remove the toner on the cleaning roller, 27 is an upper bias blade that scrapes off and removes the toner on the upper bias roller 26, and 28 is scraped by the bias blades 25 and 27. Toner that discharges the dropped toner to the transport section outside the cleaning device A screw, 29 is a case of the cleaning device (cleaning case), 30 is a power supply 30a for applying a predetermined bias voltage to the cleaning roller 23 to form an electric field so that the toner on the photosensitive drum 1 is directed to the cleaning roller 23. Laura 2
A power supply 30 for applying a voltage having a polarity to transfer the toner on the lower bias roller 24 to the lower bias roller 24.
b, a cleaning power source including a power source 30c for applying a voltage having a polarity to transfer the toner on the cleaning roller 23 to the upper bias roller 26. Further, reference numeral 31 is a discharge lamp for discharging the photosensitive drum 1 after cleaning.

The operation of the printer having the configuration shown in FIG. 1 will be described below. It should be noted that a series of image forming processes is performed here with an example of N / P. In FIG. 1, when a print button (not shown) of the operation unit is pressed, the charging roller 2, the developing roller 5, the transfer roller 17, the paper discharging needle 19, the cleaning roller 23, and the lower bias roller 2 shown in the drawing are pressed.
4, the upper bias roller 26, each power source 3, 11, 18,
A predetermined voltage is applied by each of 20, 30 (30a, 30b, 30c). Then, by a driving mechanism (not shown), the photosensitive drum 1, the charging roller 2, the developing roller 5, the left screw 6, the right screw, the transfer roller 17, the paper conveying roller 21, the cleaning roller 23, the lower bias roller 24, the upper bias roller 26, and the toner. Each of the transport screws 28 starts to rotate in a predetermined rotation direction.

Then, the photosensitive drum 1 is discharged by the discharging lamp 31, is uniformly negatively charged (for example -850 V) by the charging roller 2 which is rotating in contact, and a latent image is formed by the laser beam 4 from the optical writing device. (For example, the black solid potential is -1
50V) is applied. The latent image is developed by a magnetic brush formed by the developing roller 5 (for example, the applied voltage of the developing bias is −650V), and a toner image is formed on the photosensitive drum 1. Then, the toner image is the photosensitive drum 1.
The transfer paper 16 is fed from a paper feed mechanism (not shown) at the timing of reaching the transfer position between the transfer roller 17 and the transfer roller 17, and the upper registration roller 12 and the lower registration roller 13 synchronize with the leading edge of the image. The toner image is supplied to the transfer position, and the transfer roller 17 transfers the toner image onto the transfer paper 16 (for example, the transfer bias is +10 μA). After the transfer, the transfer paper 16 is separated from the photoconductor drum 1 by the charge removal by the paper charge removal needle 19, and is then transported by the paper transport belt 22. Then, the toner image is fixed through a fixing device (not shown), and a copy is made. The paper is ejected to a paper ejection tray or the like. On the other hand, after the transfer of the toner image, the transfer roller residual toner is removed from the photosensitive drum 1 by the cleaning roller 23 of the cleaning device, and the charge removal lamp 31 removes the charge.

Next, the operation of the cleaning device will be described in detail with reference to FIGS. 2 is a diagram showing the transition of the toner polarity from after the development to immediately after the cleaning roller 23 removes the toner from the photosensitive drum 1, and FIG. 3 shows the transfer residual toner 34 being frictionally charged by the cleaning roller 23. Shown in FIG. 4 is the cleaning roller 2.
FIG. 6 is a diagram showing a change in polarity after the toner on the photoconductor 3 is removed and before the photoconductor drum 1 is encountered again.

As shown in FIG. 2, almost all the developed toner 32 developed by the developing roller 5 has the "negative (-) polarity",
Since the transfer roller 17 performs the transfer by the "positive (+) electric field", the transfer residual toner 34 is transferred to the cleaning roller 23 in the state where the toners of both "+" and "-" are present. Then, as shown in FIG. 3, in the nip region composed of the photosensitive drum 1 and the cleaning roller 23 pressed, the transfer residual toner 34 in which both polarities of “+” and “−” are mixed.
Is triboelectrically charged to have the same polarity (-polarity) as the toner 32 after development, and a voltage having a polarity opposite to the toner polarity after development (for example, +20
(0 V) is transferred to the cleaning roller 23 to which it is applied and held. However, as shown in FIG. 3, all of the transfer residual toner 34 has the same polarity (-polarity) as the toner 32 after development due to frictional charging.
However, the polarity is slightly opposite (+) to the toner 32 after development.
As it is, it is mechanically removed by the cleaning roller 23 and transferred onto the cleaning roller 23. The surface potential of the photosensitive drum 1 after the transfer is about "0V".

Next, as shown in FIG. 4, the removed toner 35 containing a small amount of "+ polarity toner" on the cleaning roller 23 is positioned by the rotation of the cleaning roller 23 (positioned on the upstream side in the rotational direction of the cleaning roller 23). It is transferred to a lower bias roller 24 (which is a bias roller).
A voltage (+500) having a polarity opposite to that of the toner 32 after development is applied to the lower bias roller 24, and a toner having the same polarity as that of the toner 32 after development on the cleaning roller 23 ((500) is applied between the cleaning roller 23 and the lower bias roller 24. An electric field is formed such that (-polar toner) is directed toward the lower bias roller 24, and toner having the same polarity as the toner 32 after development (-polar toner) is selectively transferred to the lower bias roller 24.
After collecting the lower bias roller 24, the toner 37 transferred to the lower bias roller 24 is transferred to the lower bias blade 25 by the rotation of the lower bias roller 24, scraped off by the lower bias blade 25, dropped to the toner discharging screw 28, and discharged. It is discharged to the outside of the unit by the screw 28 and is recycled to the developing device via a not-shown conveying unit or is conveyed to a not-shown discharged toner storage unit.

On the other hand, the lower bias roller recovery residual toner 38 on the cleaning roller 23 after passing through the lower bias roller 24 does not transfer to the lower bias roller 24 and is slightly contained in the removed toner 35 as “+ polarity toner”. The remaining “−polarity toner” that cannot be collected by the bias roller 24 and is mixed is transferred to the upper bias roller 26 portion (which is a bias roller located on the downstream side in the rotation direction of the cleaning roller 23). A voltage having the same polarity as the toner 32 after development (for example, −
500 V) is applied, and between the cleaning roller 23 and the upper bias roller 26, toner having a polarity opposite to that of the developed toner 32 (+ polarity toner) slightly contained in the developed toner 32 on the cleaning roller 23 is the upper bias roller. Two
6 to form an electric field toward the upper bias roller 26.
After development, toner of opposite polarity to toner 32 (+ polarity toner)
Are selectively transferred. The toner 39 after collecting the upper bias roller transferred to the upper bias roller 26 is transferred to the upper bias blade 27 by the rotation of the upper bias roller 26, scraped off by the upper bias blade 27, and dropped to the toner discharge screw 28. The toner is discharged to the outside of the unit by the toner discharge screw 28, and is recycled to the developing device through a not-shown conveying section or is conveyed to a not-shown discharged toner storage section.

Toner 40 after collecting the upper bias roller on the cleaning roller 23 after passing through the upper bias roller 26
Is "-polar toner" that cannot be completely collected by the lower bias roller 24. Further, since the amount of “+ polarity toner” collected by the upper bias roller 26 is considerably smaller than that of “−polarity toner”, almost all of the upper bias roller 26.
Collected by Then, the upper bias roller recovery residual toner 40 having only “−polarity” again contacts the photosensitive drum 1, but the upper bias roller recovery residual toner 40 does not reattach to the photosensitive drum 1, and the cleaning roller 23 As a result, the next transfer residual toner 34 is removed from the photosensitive drum 1. That is, the “−polarity toner” on the cleaning roller 23 is a voltage (for example, +200) having a polarity opposite to that of the developed toner 32 applied to the cleaning roller 23.
Since the toner is adsorbed on the cleaning roller 23 by V), the toner is not redeposited on the photosensitive drum 1 and the next toner can be removed. Further, the recovery residual toner 40 on the cleaning roller 23 is also after being recovered by the two bias rollers 24 and 26 as described above, so that the next toner removal can be performed with a small amount. Therefore, the toner removal performance can be improved. Since the cleaning device of the present invention does not perform the precharger as in the prior art, it does not generate ozone and does not adversely affect the environment.

[0020]

As described above, in the cleaning device according to the first aspect, since the two bias rollers that rotate in contact with the cleaning roller are provided, the bias roller on the upstream side in the rotation direction of the cleaning roller. The toner on the cleaning roller can be collected with, and the toner that cannot be completely collected can be collected by the bias roller on the downstream side. Therefore, a larger amount of toner on the cleaning roller can be collected as compared with the conventional device. When the portion of the cleaning roller that has passed through the bias roller again meets the image bearing member, the toner does not redeposit and the toner removal performance can be improved. Therefore, it is possible to prevent problems such as dirt on the charging roller. In addition, no ozone is generated and the environment is not adversely affected.

According to the cleaning device of the second aspect, in addition to the configuration of the first aspect, voltages of "+ polarity" and "-polarity" are applied to each of the two bias rollers. The toners of different polarities after being removed from the cleaning roller after being removed from the image carrier can also be selectively collected by the two bias rollers, and the portion of the cleaning roller after passing through the bias roller meets the image carrier again. In this case, there is no re-adhesion of toner and the toner removal performance can be further improved. Therefore, it is possible to prevent problems such as dirt on the charging roller.

In the cleaning device according to a third aspect of the present invention, in addition to the structure of the first aspect, the voltage applied to the two bias rollers has a polarity opposite to that of the toner after development from the upstream side in the rotation direction of the cleaning roller. (For example, + polarity), and then “the same polarity as the toner after development (for example, −polarity)”, the polarity opposite to that of the toner after development (+ polarity) included in a large amount of toner on the cleaning roller.
The "toner" is selectively collected by the downstream bias roller from the amount after "-polar toner", which occupies most of the removed toner amount, is collected by the upstream bias roller by half or more. After development, opposite polarity to toner (+
(Polarity) toner ”can be collected, and when the portion of the cleaning roller after passing the bias roller encounters the image carrier again,
It is possible to further improve the toner removing performance without re-adhesion of the toner. Therefore, it is possible to prevent problems such as dirt on the charging roller.

In the cleaning device according to the fourth aspect, in addition to the configuration of the first aspect, the applied voltage of the bias roller provided on the upstream side in the rotation direction of the cleaning roller among the two provided bias rollers is " 6. The toner having the same polarity as that of the toner after development has a voltage such that an electric field is generated toward the bias roller, so that the toner having the same polarity as the toner after development can be recovered from the toner on the cleaning roller. In the cleaning device according to the first aspect, in addition to the configurations according to the first and fourth aspects, the applied voltage of the bias roller provided on the downstream side in the rotation direction of the cleaning roller is "toner having a polarity opposite to that of the toner after development" toward the bias roller. Since the voltage is such that an electric field is generated, it is possible to collect the toner remaining on the cleaning roller and having a polarity opposite to that of the toner after development. Therefore, according to the constitutions of claims 4 and 5,
The "toner having the same polarity as the toner after development" on the cleaning roller is collected by the bias roller on the upstream side, and the "toner having the opposite polarity to the toner after development" is collected on the bias roller on the downstream side. Almost all the toner can be collected, and then the portion of the cleaning roller after passing through the bias roller encounters the image carrier again, and the frictional charging of the toner when removing the transfer residual toner can be efficiently performed. The toner removal performance can be further improved. Therefore, it is possible to prevent problems such as dirt on the charging roller.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a printer (or a printer unit of a copying machine or a facsimile) showing an example of an image forming apparatus equipped with a cleaning device of the present invention.

FIG. 2 is a diagram for explaining the operation of the cleaning device according to the present invention, and is a diagram showing a transition of toner polarity from after development until immediately after the cleaning roller removes toner from the photosensitive drum.

FIG. 3 is a diagram for explaining the operation of the cleaning device according to the present invention, showing how the transfer residual toner is frictionally charged by the cleaning roller.

FIG. 4 is a diagram for explaining the operation of the cleaning device according to the present invention, and is a diagram showing a change in polarity from after removal of toner on the cleaning roller to before encountering the photosensitive drum again. .

[Explanation of symbols]

 1 Photoreceptor Drum (Image Carrier) 2 Charging Roller 5 Developing Roller 16 Transfer Paper 17 Transfer Roller 19 Paper Eliminating Needle 22 Paper Conveying Belt 23 Cleaning Roller 24 Lower Bias Roller 25 Lower Bias Blade (Scraping Member) 26 Upper Bias Roller 27 Upper bias blade (scraping member) 28 Toner discharge screw 29 Cleaning case 30 Cleaning power source 30a Cleaning roller power source 30b Lower bias roller power source 30c Upper bias roller power source 31 Elimination lamp 32 Developed toner 34 Transfer residual toner 35 Toner after removal 36 Triboelectrically charged toner 37 Toner after collecting lower bias roller 38 Toner remaining after collecting lower bias roller 39 Toner after collecting upper bias roller 40 Upper toner remaining after collecting bias roller

Claims (5)

[Claims] 1. An endless image carrier rotates while being pressed,
A cleaning roller including a conductive member that removes the toner on the image carrier by frictionally charging the transfer residual toner having a mixture of positive (+) and negative (-) polarities to make the polarity of the toner after development, and the cleaning roller. Means for applying a voltage to the image carrier to form an electric field that directs the toner on the image bearing member toward the cleaning roller; a bias roller that rotates in contact with the cleaning roller to remove the toner on the cleaning roller; A cleaning device comprising means for applying to the bias roller a voltage for transferring the toner on the roller to the bias roller, and a scraping member for removing the toner on the bias roller, the cleaning device being in contact with the cleaning roller. Cleaning device characterized by comprising two bias rollers that rotate in parallel Place. 2. The cleaning device according to claim 1, wherein the applied voltages to the two bias rollers are “+ polarity” and “−polarity”. 3. The voltage applied to the two bias rollers is “reverse polarity to toner after development” and then “same polarity to toner after development” from the upstream side in the rotation direction of the cleaning roller. The cleaning device according to claim 1, wherein: 4. The applied voltage of the bias roller provided upstream of the cleaning roller in the rotational direction of the two provided bias rollers is "toner having the same polarity as the toner after development" applied to the bias roller. The cleaning device according to claim 1, wherein the voltage is such that an electric field directed thereto is generated. 5. The applied voltage of the bias roller provided downstream of the cleaning roller in the rotation direction of the two provided bias rollers is "toner having a polarity opposite to that of the toner after development" applied to the bias roller. 5. The voltage according to claim 1 or 4, wherein the voltage is such that an electric field directed thereto is generated.
A cleaning device as described.