JP2715292B2 - Magnetic brush cleaning device for image forming equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of transferring a toner image formed on a latent image carrier to a transfer material, and then removing toner remaining on the latent image carrier.
The surface of the latent image carrier is cleaned by removing it from the latent image carrier by a magnetic brush of a quenching agent having a toner and a carrier magnetically supported on the brush carrier and having mutually opposite polarities. The present invention relates to a magnetic brush cleaning device of an image forming apparatus that collects toner on a brush carrier transferred to an agent into a toner collecting member.

2. Description of the Related Art In an image forming apparatus that repeatedly forms a toner image on a latent image carrier and transfers the toner image to a transfer material, for example, in a copying machine or a printer, the residual toner on the latent image carrier is It is well known in the art that the surface is removed and the surface is cleaned (for example, see JP-A-58-82).
No. 283). In this type of cleaning device, a voltage having a polarity capable of adsorbing the residual toner on the latent image carrier to the brush carrier is applied to the brush carrier, and the brush carrier is similarly applied to the toner collecting member. A voltage having a polarity capable of collecting the toner on the body toward the toner collecting member is applied. For this purpose, conventionally, a power source is connected to each of the brush carrier and the toner collecting member, and a predetermined voltage is applied to each of them.
A high current flows between the brush carrier and the latent image carrier, which reverses the charging polarity of the toner, which adheres to the latent image carrier side and reduces the cleaning ability of residual toner on the carrier. There was a fear that it would be.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a magnetic brush cleaning device of the type described at the beginning, which eliminates the above-mentioned disadvantages of the prior art and can further improve the cleaning properties.

In order to achieve the above object, the present invention provides a magnetic brush cleaning apparatus of the type described at the beginning, wherein a power supply insulated from the ground is connected between the toner collecting member and the brush carrier, and a latent image carrier is provided. Another magnetic power supply is proposed in which another power supply is connected between the body and the brush carrier, and each of the power supplies is a constant current type power supply.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings, and the above-described conventional problems will be more specifically clarified with reference to the drawings.

FIG. 1 is a sectional view schematically showing an electronic copying machine as an example of an image forming apparatus provided with a magnetic brush cleaning device. In the copying machine shown here, a document 2 is placed on a contact glass 1 fixed to the upper part of the main body, and the entire surface is instantaneously illuminated by light sources (flash lamps) 3a and 3b, so that the entire image on the document surface is Is simultaneously exposed on an endless belt-shaped photosensitive member 4 which is an example of a latent image carrier. The endless belt-shaped photoconductor 4 is stretched around a driving roller 5 and three driven rollers 6, 7, and 8. Photoconductor 4
Is given a predetermined tension by a spring. A photoreceptor unit is constituted by the photoreceptor 4 and other elements, and this unit is configured to be pulled out toward the front by upper and lower slide rails 10 and 11. It is supported by front and rear unit side plates not shown. A drive motor 12 is supported on the rear unit side plate, and the motor 12 drives and controls the belt photoconductor 4 independently via the drive roller 5.

At the start of the copying operation, first, a sheet feeding device and a magnetic brush cleaning device 29, which will be described later, and other elements start operating by the drive motor 12 and a main motor (not shown),
At the same time, the belt photoconductor 4 rotates in the arrow Z direction. When the mark detection sensor 13 detects a synchronization mark (not shown) provided at the side end portion of the belt photoconductor, the operation starts at a set timing of the image forming elements around the belt photoconductor. That is, first, the photoreceptor surface is charged to a predetermined polarity by the charging charger 14. In this case, in this example, the organic semiconductor (OP
The photoconductor 4 of C) is used, and the photoconductor 4 is negatively charged. On the other hand, the reflected light from the original, which has been entirely exposed by the light sources 3a and 3b as described above, is reflected by the first mirror 15, the lens 16, and the second mirror.
The light passes through 17 and irradiates the exposed surface of the belt photoreceptor 4, where a document image is formed. In this way, an electrostatic latent image corresponding to the image of the original is formed on the photoreceptor surface, and this latent image is
The rotation of the photoconductor 4 reaches the developing device 18, and at this time, the latent image is converted into a toner image (visible image) by the toner. In this example, the toner is charged to the positive polarity opposite to the charging polarity of the electrostatic latent image on the photoconductor 4, and this is electrostatically attached to the latent image to form a toner image.

On the other hand, the transfer material (normally, the transfer paper) in the paper feeder corresponding to the selected size among the paper feeders 19, 20, and 21 is indicated by arrows A and B.
Alternatively, as shown by C, the image is supplied to the transfer unit 9. The transfer material reaching the transfer unit 9 is subjected to a discharging action by the transfer charger 22 from one surface thereof, and is discharged from the back side of the photoconductor 4 by a discharging lamp.
Light is irradiated by 23, and the toner image on the photoconductor is transferred to the transfer material. Next, the transfer material is separated from the photoconductor 4.
At this time, if the roller diameter of the roller 7 is as small as about 26 mm, for example, the transfer material can be separated from the photoreceptor 4 by using a paper strainer of the transfer material, but in the example shown in FIG. The transfer material is reliably separated from the photoreceptor 4 by the AC separation charger 24 in order to enhance reliability.

The transfer material onto which the toner image has been transferred passes through a fixing device 25 (arrow D), where the toner image is fixed, and then the arrow E
The paper is discharged to the paper discharge tray 26 as shown by.

As shown in FIG. 2, the residual toner T after the transfer remaining on the photoreceptor 4 is processed by the quenching charger 27 and the pre-cleaning charger 28, and after the charge is made uniform, the cleaning device 29 Will be cleaned. In this way, the next toner image forming step can be performed.

The quenching charger 27 has a function of removing the residual toner T on the photoconductor 4, and the charger 28 before cleaning.
Has a function of uniformly charging the residual toner in one direction (plus side in this example). For example, a voltage of AC 8 KV is applied to the corona wire of the quenching charger 27 and a voltage of DC + 6 KV is applied to the corona wire of the charger 28 before cleaning, and the residual toner T passing through these chargers 27 and 28 has a positive charge. It becomes toner.

As shown in FIG.
Photoreceptor substrate 50 consisting of a μ-thick polyester film
And a conductive layer 51 composed of a 300 to 500 mm thick aluminum vapor-deposited layer laminated thereon, and an OPC laminated thereon.
Layer (organic optical semiconductor layer) 52 and conductive layers located on both sides thereof
An electrically conductive paint layer 53 is in contact with the paint layer 51, and the paint layer 53 is in contact with the ground brush 41 (see also FIG. 1). OPC
Layer 52 is 300-500 mm thick CGL layer 52a and 20μ thick CT
It is composed of the L layer 52b. As the photoconductor 4, a transparent OPC having a transmittance of about 10 to 20% for light having a wavelength of 930 nm is used.
The transfer efficiency and the cleaning efficiency are increased by irradiating light according to FIG. The light from the neutralizing lamp 23 is cut on the short wavelength side by the filter 33,
Is prevented from deteriorating.

FIG. 2 shows the details of the magnetic brush cleaning device 29. This magnetic brush cleaning device 29 is a cleaning opposing roller disposed on the back side of the belt-shaped photoconductor 4.
The cleaning sleeve 30 has a cleaning sleeve 30 opposed to the photoconductor 4. The sleeve 30 is made of a conductive non-magnetic material, for example, aluminum.

The cleaning sleeve 30 is driven to rotate counterclockwise in FIG. Inside the sleeve 30 is an appropriate number of magnets fixed at both end shafts, in the example shown in FIG.
These magnets 54 are magnetized such that the side facing the cleaning sleeve 30 is marked with S and N in FIG.

On the peripheral surface of the cleaning sleeve 30, a cleaning agent 31 having a toner and a carrier charged with opposite polarities to each other is provided.
The carrier is, for example, iron powder of a core having a particle size of about 100 μm, and the surface thereof is coated with a resin containing carbon. A mixture of powder and resin is used. 5 and 6 (a) schematically show the carrier and the toner, 31a shows the particles of each carrier, 31b shows its core, and 31c shows the resin coating layer around it. ing. T is a particle of the toner. The cleaning sleeve 30 is, for example, 60
The diameter of the cleaning agent 31 on the surface is, for example, about 630 g.

The cleaning agent 31 is carried on the peripheral surface of the sleeve 30 by the magnetic force of the magnet 54 in the cleaning sleeve 30, and is conveyed counterclockwise in FIG. 2 while forming a magnetic brush with the rotation of the sleeve 30. . As described above, in the present embodiment, the cleaning sleeve 30 magnetically supports the cleaning agent 31 and constitutes an example of a brush carrier that conveys the cleaning agent while forming a magnetic brush made of the cleaning agent 31. .

The opposing roller 34 for guiding the photoreceptor 4 is supported at both ends by bearings (not shown), and an upper portion of a holder (also not shown) of the bearing is provided with a cleaning casing.
55 is pressed against a part of the side plate by a plate spring 35, and the opposing roller 34 or the photoreceptor 4 and the cleaning sleeve
A predetermined gap is formed between the gap and the gap 30. The gap between the cleaning sleeve 30 and the photoconductor 4 is, for example, 2.0 m
Set to m.

As shown in FIG. 4, a bias voltage having a polarity opposite to the charging polarity of the residual toner T passing through the chargers 27 and 28, that is, a negative bias voltage in this example, is applied to the cleaning sleeve 30 by a power source 56 as shown in FIG. As the carrier rotates, the carrier of the cleaning agent 31 and the toner are frictionally charged, and the carrier in the cleaning agent 31 is negatively charged (see FIG. 5). The configuration related to the power supply 56 will be described later in detail.

In the above-mentioned state, the endless belt-shaped photoconductor 4 moves in a direction opposite to the cleaning sleeve 30 that rotates counterclockwise. At this time, the residual toner T on the photoconductor 4 has the opposite polarity. (FIG. 5). Thus, the residual toner T on the photoconductor 4
Is cleaned. The function of cleaning residual toner can also be obtained by the stripping force of the magnetic brush.

Reference numeral 57 in FIG. 2 denotes a regulating member that regulates the layer thickness of the cleaning agent 31 carried by the cleaning sleeve 30 while scraping off a part thereof. The doctor section 36 regulates the thickness. Each end of the regulating member 57 in the longitudinal direction is integrally fixed to the front and rear side plates of the cleaning casing 55 by screws or the like. The gap between the cleaning sleeve 30 and the doctor section 36 is set to, for example, about 2.0 mm, and when the cleaning agent 31 passes through the gap, the layer thickness is regulated. Further, an agent reservoir 58 for the cleaning agent scraped by the doctor unit 36 is formed on the upstream side portion of the doctor unit 36.

The regulating member 57 is formed in a hollow shape having a hollow portion 70 therein, thereby preventing the spent agent from cooling the cleaning agent and sticking the toner to the carrier.

As described above, the residual toner removed from the photoconductor 4 is
The toner in the cleaning agent is collected by a toner collection roller 37 that is attached to the carrier of the cleaning agent and is conveyed downstream of the doctor unit 36 of the cleaning sleeve 30. At that time, not all the toner in the cleaning agent is collected, but a predetermined amount of toner is left in the cleaning agent, which constitutes the cleaning agent together with the carrier. Thus, the cleaning agent 31
It always contains carrier and toner.

The toner collecting roller 37 is an example of a toner collecting member. In the illustrated example, the toner collecting roller 37 includes a metal core bar 37b and an outer layer 37a (for example, a Teflon-based dielectric heat-shrinkable tube) coated on its peripheral surface. The gap between the cleaning sleeve 30 and the toner collecting roller 37 is set to, for example, about 1.7 mm. The toner collecting roller 37 is driven to rotate clockwise in FIG. 2, and its core bar 37b is supplied with a power supply 56a as shown in FIG. In the present example, a negative voltage is applied, whereby the toner in the cleaning agent is electrically sucked and collected by the collecting roller 37.
The configuration related to the power supply 56a will also be described later in detail.

As described above, the magnetic brush cleaning device 29 of the present example
After transferring the toner image formed on the latent image carrier composed of the photoreceptor 4 onto a transfer material, the toner remaining on the latent image carrier is magnetically transferred onto the brush carrier composed of the cleaning sleeve 30. The cleaning agent 31 is removed from the latent image carrier by a magnetic brush and has a toner and a carrier having oppositely charged toner and carrier, and the surface of the latent image carrier is cleaned. The toner on the carrier is collected by a toner collecting member including a toner collecting roller 37.

The toner that has electrically adhered to the surface of the toner collecting roller 37 is scraped off by a scraping blade 38 whose tip is pressed against the surface of the roller 37. The blade 38 is configured as, for example, a tip blade in which a urethane chip is inserted on a thin plate.

The toner scraped off from the toner collecting roller 37 is removed by a magnetic brush cleaning device 29 by an auger spring 39.
Transported outside the machine.

Holders 61a, 61 are provided on the upper wall of the cleaning casing 55.
Filters 40a and 40b fixed by b are provided, and air is circulated through the holes 60a and 60b in the upper wall and the filters 40a and 40b, and the pressure in the casing 55 is equal to the external pressure. ing.

Generally, in this type of cleaning device,
Cleaning agent 31 carried on cleaning sleeve 30
As the volume resistivity of the carrier inside is lower, the electric charge due to the voltage applied to the cleaning sleeve 30 extends to the most advanced carrier particles on the cleaning sleeve 30 and the effective bias at the tip of the carrier increases. Can be attracted by strong electric force, and the cleaning efficiency can be improved. FIG. 7 is an example of a graph showing the relationship between the volume specific resistivity of the carrier and the cleaning rate of the residual toner on the photoconductor. As can be seen, the volume resistivity of the carrier particles is 10 ¹⁰ Ωcm or less, especially
When the resistivity is 10 ⁸ Ω · cm or less, the cleaning rate increases. Conversely, when the resistivity exceeds 10 ¹⁰ Ω · cm, the cleaning rate sharply decreases. The cleaning rate shown here is the amount of residual toner entering the cleaning device X (mg / cm ² ), the residual toner after passing through the cleaning device,
That is, the amount of toner that could not be cleaned is represented by Y (mg / c
m ² ) It was determined by the rate (%) represented by

As described above, the lower the volume resistivity of the carrier is, the more advantageous it is. However, if it is too low, frictional charging between the carrier and the toner on the sleeve 30 is less likely to occur, and the cleaning efficiency of the residual toner T due to the frictional charging of the carrier. , The volume resistivity of the carrier is generally 10 ^{6 to} 10 ¹⁰
Ω · cm, particularly about 10 ^{6 to} 10 ⁸ Ω · cm, is preferred. In this example, a carrier of 10 ⁸ Ω · cm is used.

As described above, voltages are applied to the cleaning sleeve 30 and the toner collecting roller 37 by the power supplies 56 and 56a, respectively.

FIG. 8 shows the toner collecting roller 37, the cleaning sleeve 30, the photosensitive member, and the power supplies 56 and 5 shown in FIGS.
FIG. 6A is a diagram showing a circuit such as 6a, and each symbol is
This corresponds to each part shown in FIG. 4 and FIG. Reference numeral 4a denotes a portion corresponding to the surface of the photoconductor 4. The resistance R ₁ is the resistance of the cleaning agent 31 (FIG. 2) existing between the toner collecting roller 37 and the cleaning sleeve 30, and the resistance R ₂
Indicates the resistance of the cleaning agent 31 existing between the cleaning sleeve 30 and the photoconductor 4. Resistance R
Reference numeral 3 denotes a resistance through the CTL layer 52b, the CGL layer 52a, and the conductive layer 51 of the photoconductor 4 shown in FIG. ₃ , and the conductive layer 51 is grounded as described above. i ₁ is the current by the power supply 56a of the toner recovery roller 37, i ₂ is the cleaning sleeve 30
The current from the power supply 56 is shown. PG indicates a gap between the cleaning sleeve 30 and the photoconductor 4.

As can be seen from FIG. 8, power supply 56a is completely insulated from ground (ground or copier frame). That is, the toner collecting roller 37 (more precisely, the core 37
a) Toner recovery member and cleaning sleeve 30
A power supply 56a, which is insulated from the ground, is connected between the brush carriers composed of the photoconductor 4 and another power supply 56 is connected between the latent image carrier composed of the photoconductor 4 and the brush carrier composed of the cleaning sleeve 30. It is being done. With this arrangement, in the gap PG between the photoreceptor 4 and the cleaning sleeve 30, it will be only the current i ₂ of the power supply 56 flows to control respectively the collection function and a cleaning function of the toner by a single bias supply be able to. In addition, a constant current type power supply is used as both power supplies 56 and 56a.

Here, in order to clarify the advantages of the above configuration, a conventional voltage application method will be described with reference to the drawings.

FIG. 9 shows an example in which a voltage is applied to the cleaning sleeve 30 by a power supply 156, and a voltage is applied to the toner collecting roller 37 (more precisely, the core metal 37b) by another power supply 156a. In this example, the minus sides of the power supplies 156 and 156a are connected to the cleaning sleeve 30 and the toner collecting roller 37, respectively, and the plus sides are respectively grounded. The power supplies 156 and 156a are constant voltage power supplies.

FIG. 10 shows the configuration shown in FIG. 9 as a circuit,
FIG. 8 is a view similar to FIG. 8, and the respective reference numerals correspond to FIG. 9, and the meaning of 4a and R ₁ , R ₂ , R ₃ and PG is the same as in FIG. The i ₁ is the power supply 156a, i ₂ is the power supply 15
The currents of 6 are shown.

As is clear from FIG. 10, the cleaning sleeve 30
And i ₁ flows also to other current i ₂ is the gap PG between the photosensitive member. That is, a current of i ₁ + i ₂ flows, and a large current flows as compared with the case where only i ₂ flows as shown in FIG. When a large current flows in the gap PG as described above, the following problem occurs.

That is, as described above, the toner T in the cleaning agent 31 is originally positively charged by frictional charging with the carrier particles 31a, and the carrier is negatively charged. The situation at this time is shown in FIG. However, when a large current flows in the gap PG, as shown in FIG. 11 (b), charge injection into the toner T also causes the toner T to become negative and the polarity may be reversed. The toner T whose polarity has been reversed in this way is electrically attracted to the photoconductor 4 (FIG. 2) charged to the positive polarity by the charger 28 (FIG. 2) as shown in FIG. 11 (c). Is attached to the surface of the photoconductor 4 away from the carrier 31a. That is, the toner has adhered to the surface of the photoconductor 4 that has passed through the cleaning device 29. If such a situation occurs, the toner adheres to the background of the toner image to be formed next, and appears as a so-called background stain, which significantly reduces the image quality.

FIG. 12 is a graph showing an example of the relationship between the passing current in the gap PG and the soiling rank of the photoreceptor 4. The ranks 4 and below are ranks where soiling is remarkable and is generally not allowed. Therefore, in this example, the passing current should be suppressed to 35 μA or less, especially 30 μA or less. However, according to the conventional configuration, the passing current becomes higher than this, and there is a possibility that the background fouling becomes remarkable.

Incidentally, the area of the toner image formed by the developing device 18 shown in FIG. 1 varies depending on the area ratio of the image to the background of the document 2, and therefore, the amount of toner to be cleaned by the cleaning device 29, that is, the cleaning sleeve 30 The amount of toner adsorbed changes each time. For this reason, the toner concentration in the cleaning agent 31 changes every moment.
The resistance of the toner is greater than the resistance of the carrier,
For example, the former has a volume resistivity of 10 ^{10 to} 10 ¹⁴ Ωcm, and the latter has a volume resistivity of 10 ⁸ Ωcm, for example, as described above.
The resistance value of the cleaning agent present in the PG changes.

At that time, in the conventional configuration shown in FIGS. 9 and 10, since the constant voltage type power supply is used as the power supplies 156 and 156a, the power flows through the gap PG due to a change in the resistance value of the cleaning agent 31. The value of the current i ₁ + i ₂ also changes.

FIG. 13 is a graph showing an example of the relationship between the amount of toner in the cleaning agent 31 and the current flowing through the gap PG when the constant voltage power supplies 156 and 156a are used. As can be seen from this figure, the lower the amount of toner in the cleaning agent, that is, the lower the toner concentration, the higher the current passing through the gap PG.
For this reason, conventionally, even if the toner concentration in the cleaning agent fluctuates, unacceptable background soiling occurs in 30 to 35 μm.
The current i ₁ + i ₂ more than A was likely to flow in the gap PG. In view of the relationship of V = IR, the relationship between the toner amount and the passing current in the graph of FIG. It seems, but actually shows a slightly exponential change as shown in FIG.

Over conventional configuration described above, in the cleaning apparatus shown in FIG. 4 and FIG. 8, such as the the gap PG for current i ₂ flows only, as shown in FIG. 11 (b) Toner Can be suppressed. That is, the current flowing through the gap PG is suppressed to 35 μA or less, particularly 30 μA or less, and the ground contamination rank shown in FIG.
Higher than that. Further, since the power supply 36 is a constant current type power supply, even if the resistance value of the cleaning agent 31 existing in the gap PG changes, the current flowing therethrough can be kept constant and a large current can be prevented from flowing.
In the experiment, a high cleaning property could be obtained by setting i ₂ = 20 μA.

On the other hand, the cleaning agent 31 on the cleaning sleeve 30
The toner inside is collected by the toner collection roller 37,
At that time, as described above, a certain amount of toner should be left in the collected cleaning agent. FIG. 6 (a) schematically shows a state in which a predetermined amount of toner T in the cleaning agent 31 is left, and conversely, FIG. 6 (b)
Indicates the situation when the toner is collected too much. When the toner is excessively removed as in the latter case and the amount of toner in the cleaning agent 31 is reduced, the adjacent carrier particles 31a are removed.
The probability that the particles collide with each other is increased, whereby the resin coating layer 31c on the surface of the carrier particles is damaged, so that the toner is not triboelectrically charged, and the cleaning property is reduced. As described above, cleaning of the residual toner is performed by the Coulomb force due to the triboelectric charging of the carrier, the electric force due to the voltage applied to the cleaning sleeve 30, and the mechanical scraping force by the magnetic brush. This is because if the coat layer is broken, the Coulomb force may be lost.

However, in the illustrated cleaning device, a constant current type power supply is also used as the power supply 56a, so that an appropriate amount of toner can be collected by the toner collection roller 37 according to the amount of toner in the cleaning agent 31. That is, as the amount of toner in the cleaning agent 31 increases, the resistance value of the cleaning agent 31 increases, so that if the current i ₁ is constant, the voltage between the toner collection roller 37 and the cleaning sleeve 30 increases, and toner is removed. It can be recovered in large quantities. On the other hand, when the amount of toner in the cleaning agent decreases, the resistance value of the cleaning agent decreases, so that the voltage decreases and the amount of collected toner decreases. Thus, an appropriate amount of toner can be collected according to the amount of toner in the cleaning agent. In the experiment, i ₁ was set to 15 μA, and the toner amount of the cleaning agent 31 existing in the gap between the cleaning sleeve 30 and the toner collecting roller 37 was always about 1.2%.
(% By weight). It was also confirmed that if the amount of the toner is larger than this, there is a problem that the toner is scattered or the amount of triboelectric charge is reduced. Thus in the experiment
By setting i ₁ = 15 μA and i ₂ = 20 μA, it was possible to clean the residual toner with high reliability while suppressing the deterioration with time of the carrier.

In the embodiment described above, the brush carrier is
And the toner collecting member is constituted by the roller 37, but these may be constituted by a belt or the like. Alternatively, instead of fixing the magnet inside the brush carrier, this is driven by rotation, or the magnet and the brush carrier are The cleaning agent may be transported by rotating the body together.

Naturally, the present invention can be applied to a magnetic brush cleaning apparatus for an image forming apparatus using a latent image carrier using a dielectric, for example, other than the photoreceptor.

According to the present invention, a power supply insulated from the ground is connected between the toner recovery member and the brush carrier, and another power supply is connected between the latent image carrier and the brush carrier. A high current can be prevented from flowing between the brush carrier and the latent image carrier, thereby improving the cleaning performance of the residual toner on the latent image carrier.

Also, since each of the power supplies is a constant current type power supply, even if the resistance value of the cleaning agent existing between the latent image carrier and the brush carrier fluctuates, the current flowing there is kept constant and a large current flows. Can be blocked. Thereby, the cleaning property for the latent image carrier can be further improved.
In addition, since an appropriate amount of toner can be collected by the toner collecting member in accordance with the amount of toner in the cleaning agent, the cleaning property for the latent image carrier can be more reliably improved, and the toner in the cleaning agent can be removed. Scattering can also be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an electronic copying machine having a magnetic brush cleaning device, FIG. 2 is an enlarged cross-sectional view of the magnetic brush cleaning device, and FIG. 3 is a cross-sectional diagram schematically showing the configuration of a photoconductor. FIG. 4 is an explanatory view showing an example of a voltage application method according to the present invention. FIG. 5 is an explanatory view schematically showing a carrier and toner particles existing between a cleaning sleeve and a photoreceptor. 6 (a) and 6 (b) are explanatory diagrams for explaining a state in which a proper amount of toner is contained in the cleaning agent and a problem when the toner amount is too small, and FIG. 7 is a diagram showing the specific volume resistivity of the carrier. FIG. 8 is a diagram showing an example of a configuration according to the present invention as a circuit, and FIG. 9 is a description showing a conventional voltage application method, and FIG. Figure 10 omitting the agent, Fig. 10 Diagram showing the configuration shown in FIG. 9 as a circuit, FIG. 11 (a), (b), (c) is an explanatory view showing a situation and its problem that the toner particles are reversed to the negative polarity, 12
FIG. 13 is a graph showing the relationship between the current flowing through the gap between the cleaning sleeve and the photoconductor and the soiling rank of the photoconductor, and FIG. 13 shows a case where a constant voltage power supply is used as the power supply.
4 is a graph showing a relationship between a current flowing through the gap and an amount of toner in a cleaning agent. 29: Magnetic brush cleaning device, 31: Cleaning agent 31a: Carrier, 56, 56a: Power supply, T: Toner

Claims (1)

(57) [Claims] After transferring a toner image formed on a latent image carrier to a transfer material, the toner remaining on the latent image carrier is removed.
The surface of the latent image carrier is cleaned by removing it from the latent image carrier by a magnetic brush of a cleaning agent having a toner and a carrier magnetically supported on the brush carrier and having mutually opposite polarities. In the magnetic brush cleaning device of the image forming apparatus for collecting the toner on the brush carrier transferred to the toner to the toner collection member, a power source insulated from the ground is connected between the toner collection member and the brush carrier, Another magnetic power supply is connected between the latent image carrier and the brush carrier, and each of the power supplies is a constant current type power supply.