JPH09330002A - Cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device capable of keeping toner recovered on a cleaning roller from adhering to a photoreceptor again and preventing the contamination of an electrifying roller. SOLUTION: This cleaning device is equipped with the cleaning roller 23 consisting of a conductive member which is rotated while it is pressed to the photoreceptor 1, triboelectrifies the toner left after transfer, where positive and negative polarities coexist, and makes its polarity the same as that of the toner after developing so that the toner on the photoreceptor may be removed; a bias roller 24 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 a scraping member 25 removing the toner on the roller 24. In such a case, a charge imparting member 26 imparting charge to the toner on the roller 23 is provided between the downstream side of the contact position of the roller 23 with the roller 24 in the rotating direction of the roller 23 and the upstream side of the contact position of the roller 23 with the photoreceptor 1 in that rotating direction.

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 absorbed is reversed to the same polarity as the voltage applied to the elastic roller (the polarity opposite to the toner input to the bias roller portion). However, there is a problem in that when the toner again meets the photoconductor, the inverted toner is transferred to the photoconductor and is carried to the charging unit to stain the charging roller. Further, since the transfer residual toner is charged to one polarity by the precharger before cleaning, there is a problem that ozone is generated.

Further, in the cleaning device described in Japanese Patent Laid-Open No. 62-67578, the transfer residual toner is removed from the photosensitive member by the sponge roller, and the toner on the sponge roller is applied to the collecting roller by a polarity opposite to the toner polarity. The toner on the sponge roller after passing through the collecting roller without being completely sucked when the DC voltage is applied and electrically sucking is inverted to the same polarity as the voltage applied to the collecting roller.
There is a problem in that when the toner again meets the photoconductor, the reversed toner is transferred to the photoconductor and is carried to the charging unit to stain the charging roller.

The present invention has been made to solve the above-mentioned drawbacks of the prior art. Even when the toner collected on the cleaning roller encounters the photoconductor again, it does not adhere to the photoconductor again. An object (object) is to provide a cleaning device capable of solving problems such as dirt on the charging roller.

[0006]

In order to solve the above-mentioned problems, the present invention rotates while being pressed by an endless image carrier to rub off transfer residual toner having a mixture of positive (+) and negative (-) polarities. A cleaning roller formed of a conductive member that removes the toner on the image carrier by charging the toner to polarize the toner after development, and applies a voltage to the cleaning roller to direct the toner on the image carrier to the cleaning roller. Means for forming such an electric field, 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. And a scraping member that removes the toner on the bias roller. A charge applying member for applying an electric charge to the toner on the cleaning roller is provided downstream of the bias roller contact position in the cleaning roller rotation direction and upstream of the contact position between the cleaning roller and the image carrier. There is (claim 1).

Here, the charge applying member is a member having a plate shape, a roller shape, a brush shape, a sawtooth needle shape, or a corona wire shape, and is fixed to the cleaning roller in a pressure contact or non-contact state. It is arranged (claims 2 to 7).

A voltage having the same polarity as the toner after development is applied to the charge applying member (claim 8).

That is, in the cleaning device of the present invention, the toner on the cleaning roller is located downstream of the bias roller contact position in the cleaning roller rotation direction and upstream of the contact position between the cleaning roller and the image carrier. A charge applying member (either in the shape of a plate, a roller, a brush, a sawtooth needle, or a corona wire) that applies a charge to the cleaning roller (fixed to the cleaning roller in a pressure contact or non-contact state) Since a voltage having the same polarity as the toner after development is applied to the charge applying member, the toner having the polarity opposite to that of the toner after development remains on the cleaning roller when the toner is collected by the bias roller. In this case, the toner remaining on the cleaning roller can be made to have the same polarity as that of the toner after development by the charge giving member again. But even when I met again the photoreceptor,
It is possible to prevent reattachment to the photoconductor.

According to the cleaning device of claim 9,
A charge applying member that applies an electric charge to the toner on the cleaning roller is provided downstream of the bias roller contact position in the cleaning roller rotation direction and upstream of the contact position between the cleaning roller and the image carrier. In the case where the charge applying member has any one of a plate shape, a roller shape, and a brush shape, the charge applying member causes the toner on the cleaning roller after passing through the bias roller to have the same polarity as the toner polarity after development. Since the material is triboelectrically charged, even if the toner that has the polarity opposite to that of the toner after development remains on the cleaning roller when the toner is collected by the bias roller, the collected residual toner is used by the charge applying member. It can be triboelectrically charged to have the same polarity as the toner after development, and even when the toner on the cleaning roller meets the photoreceptor again, It is possible to avoid re-deposition on the optical element. Moreover, it is possible to adopt a configuration in which no voltage is applied to the charge applying member.

[0011]

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).

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 bias roller that rotates in contact with the cleaning roller 23 to remove the toner on the cleaning roller, 25 is a bias blade that scrapes and removes the toner on the bias roller 24, and 26 is a cleaning roller. A plate-shaped charge-giving member (charge-giving plate) that is installed downstream of the bias roller contact position in the roller rotation direction and upstream of the contact position between the cleaning roller and the photoconductor drum and that charges the toner on the cleaning roller. , 27 is a charge-giving plate holder, 28 is a toner scraped off by the bias blade 25. Toner discharging screw for discharging the transport section of the cleaning device out, 29 the case of the cleaning device (cleaning case), 30 the photosensitive drum 1 by applying a predetermined bias voltage to the cleaning roller 23
The power supply 30a that forms an electric field that directs the toner on the cleaning roller 23 to the cleaning roller 23, the power supply 30b that applies a voltage that transfers the toner on the cleaning roller 23 to the bias roller 24, and the charge applying plate 26 are predetermined. This is a cleaning power source including a power source 30c for applying a voltage of the polarity. 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, the bias roller 24,
Each of the power supplies 3, 11, 18, 20, 30 is attached to the charge applying plate 26.
Predetermined voltages are applied by (30a, 30b, 30c). 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, and the bias roller 2 are driven by a driving mechanism (not shown).
4. The toner conveying screw 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). Then, the transfer paper 16 after transfer 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, and the toner image is fixed through a fixing device (not shown) to form a copy. 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. FIGS. 4A and 4B are diagrams showing a change in polarity after the toner is removed on the cleaning roller and before the photosensitive drum 1 is again encountered.

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.
Are all triboelectrically charged and have the same polarity (-polarity) as the toner 32 after development, and are transferred and held to the cleaning roller 23 to which a voltage (for example, +200 V) having a polarity opposite to the toner polarity after development is applied. The surface potential of the photosensitive drum 1 after the transfer is about “0V”.

Next, as shown in FIG. 4, the removed toner 35 on the cleaning roller 23 is removed by the cleaning roller 23.
Is rotated to move to the bias roller 24. The bias roller 24 develops toner 32 on the bias roller 24 so as to form an electric field in which the removed toner 35 is directed from the cleaning roller 23 to the bias roller 24.
A voltage having a polarity (for example, +800 V) opposite to that of the toner is applied to the bias roller 2 to remove about half the toner 35 after the removal.
Transfer to 4. The toner 37 after collecting the bias roller transferred to the bias roller 24 is transferred to the bias blade 25 by the rotation of the bias roller 24, scraped off by the bias blade 25, dropped to the toner discharge screw 28, and cleaned by the toner discharge screw 28. The toner is discharged to the outside of the case 29 and is recycled to the developing device via a not-shown conveying unit or is conveyed to the discharged toner storage unit.

On the other hand, the bias roller recovery residual toner 38 on the cleaning roller 23 that cannot be completely collected by the bias roller 24 is biased to the cleaning roller 23 when the removed toner 35 on the cleaning roller 23 is transferred to the bias roller 24. Due to the strong electric field formed by the roller 24, about 30% is reversed to the polarity (+) opposite to that of the toner 32 after development. The bias roller recovery residual toner 38 is transferred to the portion of the charge applying plate 26 by the rotation of the cleaning roller 23, but when passing through the charge applying plate 26 to which the voltage (-) having the same polarity as that of the toner 32 after development is applied, " The “+ polarity toner” is inverted to the “−polarity toner”. Then, the charge-applied toner 39, which has the same polarity as that of the post-development toner, “-polarity only”, comes into contact with the photosensitive drum 1 again.
The toner 39 does not redeposit on the photoconductor drum 1 after the charge is applied, and the next transfer residual toner 34 is removed from the photoconductor drum 1 by the cleaning roller 23. That is, the “−polarity toner” on the cleaning roller 23 is adsorbed on the cleaning roller 23 by the voltage (for example, +200 V) of the polarity opposite to that of the toner 32 after development applied to the cleaning roller 23, so that the photosensitive drum 1 is exposed. The next toner removal can be performed without re-adhesion of the toner.

In the above example, the cleaning power source 30
In the above description, the voltage is applied to the charge applying plate 26 by the internal power supply 30c. However, when the charge applying plate 26 is contacted with the bias roller recovery residual toner 38, it is frictionally charged to the toner polarity (-polarity) after development. For example, nylon such as "+
In the case of using a "charge series" material, the bias roller recovery residual toner 38 becomes "-polar toner" having the same polarity as the developed toner by frictional charging without applying a voltage to the charge applying plate 26. Since it is inverted, the power supply 30c can be omitted.

Next, in the examples of FIGS. 1 and 4, the charge applying member is composed of the plate-like charge applying portion plate 26, but as another embodiment of the charge applying member, as shown in FIG. A roller-shaped charge-giving member (charge-giving roller) 26A, a brush-shaped charge-giving member (charge-giving brush) 26B as shown in FIG. 6, and a cleaning roller 23 as shown in FIG.
A charge-giving member 26C having a saw-toothed longitudinal direction along the axis of and a cross-sectional shape of a needle (sawtooth-like needle), or a corona wire-like charge-giving member 26D as shown in FIG. 8 may be used. The same effect can be obtained by disposing the charge applying member fixedly arranged on the cleaning roller 23 in a pressure contact or non-contact state.

Of the above-mentioned charge applying members, the charge applying roller 26A and the charge applying brush 26B are used in a state of being in contact with the cleaning roller 23, and therefore, like the charge applying plate 26, the cleaning roller 23 is used.
If the upper bias roller recovery residual toner 38 is made of a material (for example, “+ charge series” material such as nylon) that is triboelectrically charged to the same polarity (eg, −polarity) as the toner polarity after development, voltage application is performed. The power supply 30c for use can be omitted.

[0023]

As described above, according to the first aspect of the present invention.
In the cleaning device described in any one of 1 to 8, the toner on the cleaning roller is charged with electric charge to the toner on the cleaning roller between the contact position of the bias roller in the rotating direction of the cleaning roller and the upstream position of the contact between the cleaning roller and the image carrier. A charge-providing member (any one of a plate shape, a roller shape, a brush shape, a sawtooth needle shape, and a corona wire shape) is provided (fixedly arranged in pressure contact or non-contact with the cleaning roller), and Since a voltage of the same polarity as the toner after development is applied to the charge-giving member, even if the toner that was reversed to the polarity opposite to that of the toner after development remains on the cleaning roller when the toner is collected by the bias roller The residual toner can be made to have the same polarity as the toner after development by the charge-imparting member, and when the toner on the cleaning roller meets the photoreceptor again. , Can prevent re-attached to the photosensitive member, it is possible to prevent the dirt of the charging roller.

According to another aspect of the cleaning device of the present invention, the toner on the cleaning roller is electrically charged between the bias roller contact position downstream of the cleaning roller rotation direction and the contact position upstream of the cleaning roller and the image carrier. When the charge applying member is provided and the charge applying member has any one of a plate shape, a roller shape and a brush shape, the charge applying member removes the toner on the cleaning roller after passing through the bias roller. Since the material is made to frictionally charge to the same polarity as the toner polarity after development, even when the toner that has been reversed to the polarity opposite to that of the toner after development remains on the cleaning roller when the toner is collected by the bias roller, The collected residual toner can be triboelectrically charged by the charge imparting member to have the same polarity as that of the toner after development, and When toner met again photosensitive member, it is possible to prevent re-attached to the photoreceptor. Moreover, since it is possible to adopt a configuration in which no voltage is applied to the charge applying member, the power supply for voltage application can be omitted, and the cost can be reduced.

[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. .

FIG. 5 is a view showing another embodiment of the present invention, and is a schematic configuration diagram of a main part of a cleaning device using a roller-shaped charge applying member.

FIG. 6 is a view showing still another embodiment of the present invention,
FIG. 3 is a schematic configuration diagram of a main part of a cleaning device using a brush-shaped charge applying member.

FIG. 7 is a diagram showing still another embodiment of the present invention,
FIG. 9 is a schematic configuration diagram of a main part of a cleaning device using a saw-toothed needle-shaped charge applying member.

FIG. 8 is a diagram showing still another embodiment of the present invention,
FIG. 4 is a schematic configuration diagram of a main part of a cleaning device using a corona wire-shaped charge applying member.

[Explanation of symbols]

 1 Photoreceptor Drum (Image Carrier) 2 Charging Roller 5 Developing Roller 12 Upper Registration Roller 13 Upper Registration Roller 16 Transfer Paper 17 Transfer Roller 19 Paper Eliminating Needle 22 Paper Conveying Belt 23 Cleaning Roller 24 Bias Roller 25 Bias Blade (Scraping Member) ) 26 plate-shaped charge-giving member (charge-giving plate) 26A roller-shaped charge-giving member (charge-giving roller) 26B brush-shaped charge-giving member (charge-giving brush) 26C serrated needle-shaped charge-giving member 26D corona-wire-shaped Charge applying member 27 charge applying plate holder 28 toner discharge screw 29 cleaning case 30 cleaning power supply 30a cleaning roller power supply 30b bias roller power supply 30c charge applying member power supply 31 static elimination lamp 32 post-development toner 34 Transfer residual toner 35 Toner after removal 36 Frictionally charged toner 38 Bias roller recovery residual toner 39 Toner after charge application

Claims (9)

[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. Downstream of the bias roller contact position of the cleaning roller and the image carrier. A cleaning device, characterized in that a charge applying member for applying an electric charge to the toner on the cleaning roller is provided upstream of the contact position with the body. 2. The cleaning device according to claim 1, wherein the charge applying member has a plate shape. 3. The cleaning device according to claim 1, wherein the charge applying member has a roller shape. 4. The cleaning device according to claim 1, wherein the charge applying member has a brush shape. 5. The cleaning device according to claim 1, wherein the charge applying member has a serrated needle shape. 6. The cleaning device according to claim 1, wherein the charge applying member has a corona wire shape. 7. The cleaning device according to claim 1, wherein the charge applying member is fixedly arranged in a pressure contact or non-contact state with the cleaning roller. 8. A voltage having the same polarity as that of the toner after development is applied to the charge applying member.
The cleaning device according to any one of 1 to 7. 9. The charge imparting member is made of a material that frictionally charges the toner on the cleaning roller after passing through the bias roller to the same polarity as the toner polarity after development. The cleaning device according to any one of 1.