JPS63147180A - Cleaning device for image forming device - Google Patents

Abstract

PURPOSE:To efficiency improve toner recovery by composing a toner recovery roller of an insulating core member and a resistance body arranged outside it and applying a bias voltage which is higher than that of a cleaning sleeve to the resistance body. CONSTITUTION:The recovery roller 37 consists of the electric insulating core member 38 and the resistance body 39 fixed outside it and a conductive member 40 contacts it to apply the resistance with the voltage higher than the voltage applied to the cleaning sleeve 31. An electric field is therefore established between the surface of the resistance body 29 of the recovery roller 37 and a carrier 33 in an area where the sleeve 31 and recovery roller 37 face each other and then toner having the positive polarity which sticks on the carrier 33 moves to the recovery roller 37. Consequently, the voltage at the resistance part facing the carrier 33 is made higher than when a metallic roller is used and the toner can be collected effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cleaning device in an image forming apparatus that cleans toner remaining on a latent image carrier after transferring a toner image formed on a latent image carrier to a transfer material. In particular, a cleaning sleeve that houses a magnet therein and supports the carrier with its magnetic force, and a voltage application means that applies a bias voltage to the cleaning sleeve with a polarity opposite to the charged polarity of the residual toner to be cleaned with the carrier on the cleaning sleeve. and a toner collecting means for collecting the cleaned toner from the cleaning sleeve side, the cleaning sleeve facing the surface of the latent image carrier so that the carrier can attract residual toner on the latent image carrier by electric force. The invention relates to a cleaning device located at

In image forming apparatuses such as copying machines and printers that repeatedly form a toner image on a latent image carrier and transfer it to a transfer material, a toner image is formed on the latent image carrier after the toner image has been transferred. It is necessary to clean the remaining toner and prepare for the next toner image forming process. The use of cleaning devices of the above type for this purpose has been known for some time (for example,
37382, JP-A-56-51768, JP-A-50-75044, etc.). This type of cleaning device, generally referred to as a magnetic brush cleaning device, applies a bias voltage to the cleaning sleeve that has the opposite polarity to the charged polarity of the residual toner to be cleaned.
Electric charge is injected into the carrier on the sleeve, and residual toner of opposite polarity is attracted to the carrier by electric force, thereby removing the residual toner from the latent image carrier. The toner transferred to the cleaning sleeve side is collected by a toner collecting means.

Conventionally, a collection roller made of conductive metal that is driven once is often used as a toner collection means, and a bias voltage of the same polarity but higher than the voltage applied to the cleaning sleeve is applied to this roller. An electric field is formed between the sleeve or the carrier on it and the first collection roller, and the toner existing in this electric field is attracted to the collection roller side by electric force to collect the toner.

By the way, in order to improve the cleaning effect in the above-mentioned type of device, the specific volume resistivity of the carrier supported on the cleaning sleeve is lowered to, for example, 1010Ω.- or less, particularly 101Ω.-1 or less, and the bias voltage applied to the cleaning sleeve is By increasing the effective bias at the carrier tip by effectively injecting charge into each carrier particle and increasing the electric field between the carrier and the WIa support, the toner present in this electric field is transferred to the carrier by a strong electric force. It is desirable to configure the device so that it can be suctioned.

However, when such a low-resistance carrier is used, the electrically conductive collection roller to which a voltage is applied and the cleaning sleeve become electrically connected via the carrier, so when the potential difference between the roller and the carrier is large, the flow through the carrier There was a risk that the carrier particles would be destroyed by the current. For this reason, conventionally it was necessary to take measures such as reducing the potential difference between the collection roller and the cleaning sleeve.
If this is done, the electric field between the collection roller and the carrier (or sleeve) will be weakened (1), resulting in a reduction in toner collection efficiency. In order to eliminate this drawback, collection rollers with insulation treatment, collection rollers with resistor coated on the surface of a metal roller to which voltage is applied, etc. have been proposed, but both completely solve the above problem. It was not possible.

The object of the invention is to provide a cleaning device of the type mentioned at the outset, which eliminates the above-mentioned conventional disadvantages.

In order to achieve the above-mentioned object, the present invention includes a toner collecting means, an insulating core member, a resistor disposed outside the core member at a position facing the cleaning sleeve, and a conductive member in contact with the resistor. At least the resistor is rotatable, and a bias voltage higher than the voltage applied to the cleaning sleeve is applied to the resistor via the conductive member.

An embodiment of the present invention will be described below with reference to the drawings, and the above-mentioned conventional structure will be explained more specifically with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of an image forming apparatus (electronic copying machine) equipped with a cleaning device according to the present invention;
In order to understand the present invention, the outline of the configuration shown here will first be briefly explained.

In the copying machine illustrated in FIG. 1, a document 2 is placed on a contact glass 1 fixed to the upper part of the main body, and a light source (flash lamp) 3a covers the entire surface of the document 2.

3b, and simultaneously projects the entire image on the document surface onto a latent image carrier configured as an endless belt-shaped photoreceptor 4. The endless belt photoreceptor 4 is passed around a driving roller 5 and three driven rollers 6, 7, 8. A predetermined tension is applied to the belt photoreceptor 4 by a spring. The photoreceptor 4 and other elements constitute a photoreceptor unit, and this unit is configured to be pulled out to the front by upper and lower slide rails 10.11. Each roller shaft end of the photoreceptor unit is supported by front and rear unit side plates (not shown).

A drive motor 12 is supported on the side plate of the rear unit, and the motor 12 independently drives and controls the belt photoreceptor 4 via the drive roller 5 .

At the start of the copying operation, the drive motor 12 and the main motor (not shown) start operating the paper feeding device, cleaning device @28, and other elements described later, and at the same time, the belt photoreceptor 4 rotates in the direction of the arrow. When the mark detection sensor 13 detects a synchronization mark (not shown) provided at the side end of the belt photoreceptor, the image forming elements around the belt photoreceptor start operating at a set timing. That is, first, the surface of the photoreceptor is charged to a predetermined polarity by the charger 14. In this example, an organic semiconductor (OPC) photoreceptor 4
is used, so it is negatively charged.

On the other hand, as described above, the reflected light from the original that has been entirely exposed by the light sources 3a and 3b is reflected by the first mirror 15. The light passes through the lens 16 and the second mirror 17 and is irradiated onto the exposed surface of the belt photoreceptor 4, whereupon the original image is formed.

In this way, an electrostatic latent image corresponding to the image of the original is formed on the surface of the photoreceptor, and this latent image reaches the developing device 18 as the photoreceptor 4 rotates. visualized). In this example, the toner is charged to a positive polarity opposite to that of the electrostatic latent image on the photoreceptor 4, and is electrostatically attached to the latent image to form a toner image.

The toner image formed as described above is transferred to the paper feeder 19.
, 20, 21, the transfer material (usually transfer paper) in the paper feeding device corresponding to the selected size is supplied to the transfer unit 9 as indicated by arrows A, B, or C. The transfer material that has reached the transfer section 9 is subjected to a discharge action by the transfer charger 22 from one side thereof.

Light is irradiated from the back side of the photoreceptor 4 by a static elimination lamp 23, and the toner image on the photoreceptor is transferred to a transfer material. The transfer material is then separated from the photoreceptor 4.

At this time, if the roller diameter of the roller 7 is small, for example 26mm, it is possible to separate the transfer material from the photoconductor 4 by the curvature using a paper strainer of the transfer material, but in the example shown in the figure, it is possible to separate the transfer material from the photoreceptor 4 by the curvature. The transfer material is reliably separated from the photoreceptor 4 by an AC separation charger 24.

The transfer material onto which the toner image has been transferred passes through the fixing device 25 (
Arrow D), the toner image is fixed here.

The paper is then discharged onto the paper discharge tray 26 as shown by arrow E.

The residual toner remaining on the photoreceptor 4 after transfer reaches the cleaning device 28, where the charge is first made uniform by the pre-cleaning charger 27. In this example, the residual toner is positively charged by the charger 27 and then cleaned from the surface of the photoreceptor. In this manner, the next toner image forming step can be performed. FIG. 2 schematically shows the residual toner on the photoreceptor 4 that has passed through the charger 27.

As indicated by the symbol T, the diameter of the toner particles is usually about several tens of microns.

The reason why the residual toner is uniformly charged to a positive polarity by the pre-cleaning charger 27 is that the toner is charged to the separation charger 2.
4, the polarity of the charged polarity is not constant, and the transfer conditions are not necessarily constant depending on the thickness of the transfer material, environment, etc., so the polarity of the toner before reaching the charger 27 is This is because the positive and negative values may vary.Also, if the transfer material is not sent to the transfer position 9 due to transportation trouble, all of the 1-toner on the photoreceptor 4-'2 that has reached the transfer position will not be transferred. , the whole is negatively charged by the transfer charger 22,
Even in such a case, the toner can be positively charged by the charger 27.

By repeating the above-described copying cycle, transfer materials on which toner images are formed can be sequentially obtained.

As clearly shown in FIG. 2, the cleaning device 28 includes, in addition to the charger 27, a cleaning sleeve 31 that faces a backup roller 30 placed on the back side of the belt photoreceptor 4 with the photoreceptor 4 in between. This sleeve is rotationally driven in the direction M1. bag up roller 30
is arranged not directly below the cleaning sleeve 31, but slightly to the left in FIG.
0 and the sleeve 31, the surface of the photoreceptor portion facing the sleeve 31 (cleaning nip ring) is widened.

An appropriate number of magnets 32 are housed inside the cleaning sleeve 31, and these magnets 1-32 are fixed in position, with S facing toward the inner circumferential surface of the sleeve 31.
They are arranged so that poles and north poles appear alternately. On the surface of the sleeve 31, a carrier 33 consisting of particles having a diameter of, for example, 120 μm is placed, similar to the carrier carried on the developing sleeve 2 of a dry-type developing device, and the toner is electrostatically held on the carrier particles. It's attached. This carrier and toner are generally referred to as cleaning agents. The sleeve 31 is made of a conductive non-magnetic material 1, such as aluminum.

Each particle of the carrier has a core 34 made of a magnetic material such as iron, as shown schematically in FIG.
9 and a coat 35 mainly made of resin, for example. The 1-toner adhering to the carrier 33 of the sleeve 31 is indicated by the symbol t in FIG. 3 in order to distinguish it from the residual toner T on the photoreceptor 4. In this way, since the core 34 is a magnetic material, the carrier 33 is supported around the sleeve 31 by the magnetic force of the magnet 32 installed inside the sleeve 31.
As the sleeve 31 rotates clockwise in FIG. 2, it is conveyed in the same direction as the sleeve while forming a magnetic brush on the circumferential surface of the sleeve. The toner may be non-magnetic 1 hener or magnetic toner, but if magnetic toner is used, the toner t on the sleeve 31 is transferred to the magnet 3.
It can also be attracted to the sleeve 31 by the magnet No. 2.

Further, a negative bias voltage having a polarity opposite to the charged polarity of the residual toner T that has passed through the charger 27 is applied to the cleaning sleeve 31 by a voltage applying means, in the example shown in the figure, a power supply 36, whereby each carrier particle on the sleeve 31 A negative charge is injected into 33 (see FIG. 3). This example is for convenience of explanation. ! , the applied voltage by JiX36 was -170v.

Residual toner T that has passed through the charger 27 before cleaning
When the photoreceptor 4 reaches the vicinity of the cleaning sleeve 31 as the photoreceptor 4 travels, the 1-ner T, which is positively charged, is attracted by the electric force to the negatively charged carrier 33, which is the opposite, and the photoreceptor 4 and adheres to the carrier 33. More specifically, since a negative voltage is applied to the sleeve 31 and the base layer of the photoreceptor 4 is grounded, an electric field is formed between them, and the positive residual toner T present in this electric field becomes a carrier. 33, that is, electrostatically transferred to the magnetic brush. The carrier 33 on the sleeve 31 facing the photoreceptor 4 and the surface of the photoreceptor 4 may be slightly apart or may be in contact with each other. The toner t is stirred and mixed with each other by the rotation of the sleeve 31,
The carrier 33 is charged with negative polarity and the toner t is charged with positive and amphoteric friction. Since the 1-toner t and the carrier 33 are moving while shifting their positions relative to each other, the charge on the carrier due to this friction can also reduce the residual toner T. is attracted to the carrier 33. The coat 35 of the carrier 33 is negatively charged by frictional charging with the toner t.

The toner transferred from the photoreceptor 4 to the carrier side.

Conveyed together with the carrier as the sleeve 31 rotates,
As shown in FIG. 2, it is collected by a collection roller (scavenge roller) 37 according to the present invention, which is placed opposite to the sleeve 31. As shown in FIGS. 6 and 7, this roller 37 is made up of, for example, a cylindrical electrically insulating core member 38 and a resistor 39 fixed to the outside thereof.
A conductive member, in the illustrated example, a conductive flocked brush 40 is in contact with the resistor 39, and a bias voltage is applied to the resistor 39 from a power source 41 through this brush.

The polarity of this voltage is the same as the voltage applied to the cleaning sleeve 31, but in the example of FIG. The carrier 33, which is rotationally driven in the clockwise direction and supported on the part of the sleeve 31 facing the collection roller 37, and the surface of the collection roller 37, that is, the resistor 39, may be in contact with each other, or may be slightly separated from each other. You can leave it there. The operation when the toner on the sleeve 31 side is transferred to the collection roller 37 will be explained later.

The toner transferred to the collection roller 37 is scraped off from the roller 37 by a blade 42 pressed against the surface of the roller 37, falls into a toner receiver 43, and is then carried out by a coil conveyor 44.

As shown in FIG. 4, the blade 42 is made of an elastic material such as fluororubber fixed to the tip of a leaf spring 45 made of phosphor bronze, for example, and the other end of the leaf spring 45 is fixedly supported by the machine frame. . Further, the brush 40 is supported by the machine frame via an insulator 46. - In the illustrated example, when the toner on the sleeve 31 passes through the collection roller 37, not all of the toner is collected by the roller 37, but a predetermined amount of toner adheres to the carrier and remains on the sleeve 31. It passes through the roller 37 as it is. This remaining toner becomes the aforementioned toner t constituting a part of the cleaning agent, and due to the friction between the toner t and the carrier 33, the carrier is triboelectrically charged and attracts the remaining toner T.

As described above, the sleeve 31 is placed opposite the photoreceptor 4 so that the carrier on the sleeve 31 can suck the residual toner T on the photoreceptor 4, and the residual toner T is cleaned. The lower the specific volume resistivity (more precisely, the volume specific resistivity of at least the surface portion of each carrier particle, in the example shown, the coat 35), the more the electric charge due to the voltage applied to the sleeve 31 will be applied to the most advanced carrier on the sleeve 31. The toner is effectively injected into the particles, which strengthens the electric field between the carrier and the photoreceptor base layer and increases the effective bias at the carrier tip, which makes it possible to attract the residual toner T with a strong electric force and improve the cleaning effect. It is possible to increase FIG. 5 is an example of a graph showing the relationship between the specific volume resistivity of the carrier and the cleaning rate of residual toner on the photoreceptor. As can be seen from this, the specific volume resistivity of the carrier is less than 1010 Ω・1, especially 10' Ω
- When the resistivity is below (7), the cleaning rate increases, and conversely, when the resistivity is higher than the above value, the cleaning rate decreases. The cleaning rate shown here is expressed as λ, where X is the amount of residual toner entering the cleaning device, and Y is the amount of residual toner after passing through the cleaning device, that is, the amount of toner that could not be cleaned. It means percentage (%). However, although some of the toner that has once transferred to the carrier 33 may be returned to the photoreceptor 4, the graph in FIG. 5 ignores the amount of this returned toner.

As mentioned above, under other conditions being the same, it is advantageous that the lower the specific volume resistivity of the carrier, the higher the cleaning rate can be. However, if this is too low, the sleeve 31
Since frictional charging between the upper carrier 33 and the toner T becomes difficult to occur, and cleaning efficiency of residual toner T due to the frictional charging of the carrier decreases, it is generally particularly preferable that the specific volume resistivity of the carrier is about 106 to 101Ω·1. From this point of view, in this example, the volume resistivity of the carrier 33 supported by the cleaning sleeve 31 is set to 10<6 >Ω.

However, when such a low-resistance carrier is used, and the collection roller is made of a conductive material such as metal as in the past, there is a risk that the carrier coat may be destroyed, as described above.

In order to understand the present invention, the above-mentioned conventional drawbacks will be explained based on the drawings. As schematically shown in Fig. 1O, a conventional collecting roller 3 is made entirely of metal and rotates clockwise.
7a, a voltage higher than the voltage applied to the sleeve 31 is applied by the power source 41a. However, roller 37
The polarity of the voltage applied to the sleeve 31 is the same, and if the polarity of the toner attached to the carrier 33 is positive as in FIG. 2, a negative voltage is applied to the collection roller 37a and the sleeve 31. . Therefore, the carrier 33 injected with negative charge through the sleeve 31 and the collection roller 37a
An electric field is applied between them, and the positively charged toner present in this electric field is attracted by the electric force to the collecting roller 37a, adheres to the roller 37a, and is collected. When the tip of the carrier 33 is in contact with the collection roller 37a as shown in FIG.
That is, an electric field is formed between the carrier and the collection roller 37a immediately before contacting the roller 37a, and between the carrier and the collection roller 37a immediately after leaving the collection roller 37a.
Toner is collected into a collection sleeve. With such a configuration, if the specific volume resistivity of the carrier 33a is low, for example, 1
0" Ω・am), as can be seen from FIG. 10, if the sleeve 31 and roller 37a are electrically connected via this carrier, leakage will occur. Therefore, the potential difference between the sleeve 31 and the collection roller 37a will be If the height is as high as in the above-mentioned example shown in the figure, the coat of carrier particles that are in contact with each other over a small area will be destroyed by the current flowing there, and the original function of the carrier will be lost. The same applies when the roller 37a is arranged so that the carrier 33 and the collection roller 37a are slightly separated from each other.For this reason, when the metal collection roller 37a is used, the specific volume resistivity is, for example, 101'Ω·1. It is necessary to use the above-mentioned high-resistance carrier or to make the potential difference between the roller 37a and the sleeve 31 low (for example, about 20 V) to suppress the current flowing through the carrier 33 and prevent the carrier from being destroyed. If a high-resistance carrier is used, as shown in FIG.
The electric field effect between the toner and the carrier is reduced, and the efficiency of toner collection to the roller 37a is reduced. When the toner recovery performance deteriorates, the ratio of toner in the cleaning agent on the sleeve 31 gradually increases, the effect of charge injection into the carrier and the charging ability decrease, and cleaning failure occurs.

A toner collecting means is also known in which the peripheral surface of the collecting roller 37a is insulated, the surface and the toner are frictionally charged, and the toner is attracted toward the collecting roller by the electrostatic force generated by the frictional charging. Although this configuration does not cause leakage problems, the toner is collected only by the electric force generated by the frictional charging between the toner and the carrier, so the collection efficiency is low, and it is difficult to handle changes in the environment, especially under high humidity. Toner collection efficiency decreases.

Furthermore, as shown in FIG. 11, a conductive metal core member 38b
A collection roller 37b coated with a resistor 39b around the roller 37b is used, a voltage is applied to the core member 38b of the roller 37b by a power source 41b, and the toner on the sleeve 31 is collected in the same manner as in the case of FIG. is also publicly known. Although it is possible to suppress the occurrence of specific leakage in the configuration shown in FIG.
If a pinhole H is formed or a scratch is made on the resistor 39b when coating the resistor 39b, the conductive core member 38b will be exposed to the surface, or the result will be the same as if the conductive core member 38b were exposed, and leakage may occur through this. There is. It is difficult to eliminate pinholes or to minimize the diameter of pinholes so as not to cause leakage due to the '15'lx technology. It is also difficult to handle the collection roller without damaging the surface.

It is also known that the collecting roller is made of aluminum and its surface is treated with alumite to achieve the same effect as the collecting roller shown in Fig. 11. There is a risk that the gold part will be exposed to the outside and leak from there.

Therefore, in the configuration according to the present invention, as described above with reference to FIGS. 2, 6, and 7, the collection roller 37 includes an insulating core member 38 and a resistor fixed around the core member 38. It consists of 39 pieces.

This collection roller 37 and the collection roller 37 shown in FIG.
The difference between the core member 38b in FIG. 11 and FIG. 11b is that the core member 38b in FIG.
For example, it is made of resin, and while in FIG. 11 the voltage is applied to the core member 38b, in FIG. 2 the voltage from the electric current g41 is applied to the surface of the resistor 39. be. In the example shown in FIG. 2, the surface resistivity of the resistor 39 is set to 107Ω. The gap between the collecting roller 37 and the sleeve 31 is 1. For example, the diameter of the core member 38 is 28 mm, and the outer diameter of the sleeve 31 is 1. When there are 60 cabinets, 21
It is set to about m.

By applying a voltage to the resistor 39, the resistor 39
A current corresponding to the surface resistivity and the applied voltage flows on the surface of the resistor 39, and a voltage is applied to the portion of the resistor facing the sleeve 31. Therefore, similar to the effect described above with reference to FIG. Carrier 33
The positive polarity toner adhering to the carrier transfers to the collection roller 37 (as mentioned above, the surfaces of the carrier and the resistor 39 may be in contact with each other or may be slightly separated from each other; this is shown in FIG. 1O). The same applies to the case of

As described above, a voltage is applied to the surface of the resistor 39 through the brush 40, and as a result, a current flows through the surface of the resistor 39 according to its surface resistivity, etc., but between the carrier 33 and the brush 40, Because the resistor 39 exists, even if there is a pinhole or some scratches on the resistor 39, the carrier 33 and the brush 40 will not be electrically connected directly through the pinhole. can prevent leaks.

Furthermore, even if the pinhole H1 as shown in FIG. 6 comes into contact with the brush 40 and the other pinhole H2 comes into contact with the carrier 33 on the sleeve 31, since the core member 38 of the collection roller 37 is an insulator, Current does not flow through the hole H1 → core member 38 → pinhole H2 and leak in the carrier 33.

In addition, the voltage at the resistor portion facing the carrier 33 can be increased compared to when a metal roller is used, and the resistor 39
Since a strong electric field can be formed between the toner and the carrier 33, the positively charged toner can be effectively attracted to the collection sleeve 37 and collected. Although the voltage of the resistor can be increased in this way, a strong current that would destroy the carrier 33 does not flow through the carrier 33, and the problem of leakage as in the conventional case does not occur. Although the reason for this is not necessarily clear, it is believed that the resistor 39 serves as a capacitor. In any case, this fact has been confirmed by various experiments. In addition, the resistor 39
In the illustrated example, the surface resistance of The toner recovery rate was obtained.

If the surface resistivity of the resistor 39 is smaller than 102, the current value flowing through the surface of the resistor becomes large and leakage is likely to occur.On the other hand, if it is larger than 1010, the voltage of the low antibody decreases, and therefore the required In order to obtain the voltage that
Therefore, the value of the applied voltage must be increased more than necessary.

For example, the collection roller 37 can be manufactured as follows.

That is, the resin core member 38 is coated with Teflon from which carbon has been separated, so that its surface resistivity is, for example, 10<7>Ω. Alternatively, the collection roller 37 may be constructed by winding a sheet having the above-mentioned surface resistivity around a core member 38 made of resin.

If resin is used as the insulating material for the core member 38 as shown in item 2, there is also the advantage that the collection roller 37 can be made lighter. In addition to resin, it is also possible to construct the core member 38 from an insulator such as glass or wood.

In the embodiment shown in FIG. 2, a voltage is applied to the resistor 39 through a conductive brush 40, but as shown in FIG. A conductive blade 142 consisting of
A voltage may be applied to. If the conductive member for voltage application is configured to also serve as a toner scraping blade, the structure can be simplified, which is advantageous.

Further, in the example shown in FIG. 2, the recovery roller 37 is formed by an insulating cylindrical core member 38 and a resistor 39 fixed to the outside thereof and disposed at a position facing the cleaning sleeve 31.
The collection roller 37 and the brush 40 constitute a toner collection means, but as shown in FIG.
A belt 139 having a surface resistivity of 1a is wound around the belt 139, this belt 139 is rotated by rollers 138 and 23g, and a voltage is applied to the surface of the belt 139 through a conductive member made of a brush 40, for example. In this structure as well, the resistor consisting of the belt 139 is located outside the core member consisting of the roller 138 and facing the cleaning sleeve 31. in this case,
It is also possible to stop the roller 138 and rotate the belt 139 while slipping it with respect to the roller 138. In short, it is sufficient that at least the resistor of the resistor and the core member is rotatable.

Further, the present invention can be applied to a cleaning device in which, for example, the cleaning sleeve is fixed without rotating, and a magnet installed inside the sleeve is rotated to convey the cleaning agent, or the sleeve and magnet are both driven to rotate. The same applies to cleaning devices such as image forming apparatuses using a drum-shaped photoreceptor or image forming apparatuses using a latent image carrier made of a dielectric material. In this case, it goes without saying that the charging polarity of the latent image carrier used, the charging polarity of the toner during development, and the polarity of the bias voltage applied to each sleeve may change depending on the properties of the latent image carrier used. For example, when a selenium-based photoreceptor is used, the photoreceptor is charged to a positive polarity by the charger 14, and the toner during development is normally charged to a negative polarity, so the toner remains in the charger 27 before cleaning. It is sufficient to charge the toner to a negative polarity and apply a positive voltage to each sleeve 31. At this time, the polarity of the voltage applied to the resistor 39 of the collection roller 37 or the belt 139 is also positive, which is opposite to the charged polarity of the toner.

According to the present invention, since the resistor is arranged in the core member of the insulator, leakage can be prevented even if there is a pinhole in the resistor, and a low-resistance carrier can be used. Furthermore, since a high electric field can be applied between the resistor and the carrier, toner recovery efficiency can be increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example of a copying machine equipped with a cleaning device according to the present invention, FIG. 2 is an enlarged sectional view showing details of the cleaning device, and FIG. 3 is an explanation schematically showing the cleaning operation. Figure 4 is a perspective view of the cleaning blade, Figure 5 is a graph showing an example of the relationship between the specific volume resistivity of the carrier and the cleaning rate, and Figure 6 is a schematic diagram showing the relationship between the collection roller, the cleaning sleeve, and the carrier. FIG. 7 is a vertical sectional view of the collection roller, FIGS. 8 and 9 are schematic configuration diagrams showing other embodiments, and FIG.
0 and 11 respectively show conventional configuration examples.
It is an explanatory diagram similar to the figure. 28...Cleaning device 31...Cleaning sleeve 32...Magnet 33...Carrier 3
8... Core member 39... Resistor element 40.
...Brush 142...Blade T...
・Residual toner Fig. 2 Fig. 9 Fig. 10 Fig. 5 Carrier 4yF Kamegata II (knee c-) Fig. 6 Fig. 9 Fig. 10 - Bar

Claims (4)

[Claims] (1) A cleaning device in an image forming apparatus that cleans the toner remaining on the latent image carrier after the toner image formed on the latent image carrier is transferred to a transfer material. a cleaning sleeve supporting a carrier; a voltage applying means for applying a bias voltage having a polarity opposite to the charge polarity of the residual toner to be cleaned with the carrier on the cleaning sleeve to the cleaning sleeve;
a toner collecting means for collecting the cleaned toner from the cleaning sleeve side, and the cleaning sleeve is positioned opposite to the surface of the latent image carrier so that the carrier can attract residual toner on the latent image carrier by electric force. In the cleaning device, the toner collecting means includes an insulating core member, a resistor disposed outside the core member at a position facing the cleaning sleeve, and a conductive member in contact with the resistor, The cleaning device, wherein at least the resistor is rotatable, and a bias voltage higher than the voltage applied to the cleaning sleeve is applied to the resistor via the conductive member. (2) The cleaning device according to claim 1, wherein the conductive member is a brush. (3) Claim 1, wherein the conductive member also serves as a blade for scraping off toner adhering to the surface of the resistor.
The cleaning device according to item 1 or 2. (4) The surface resistivity of the resistor is 10^2Ω to 10
The cleaning device according to any one of claims 1 to 3, which has a resistance of ^1^0Ω.