JPH10123900A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality image without a failure in transfer and further, to reduce the adverse influence of residual toner by enhancing the transfer rate, in a cleaningless system image forming device. SOLUTION: Toner remaining on a photoreceptor 1, without being transferred in a transferring part 5 passes through an electrifying part 2 and an exposure part 3 as it is, and is recovered in the position of a developing device 4 accompanying the rotation of the photoreceptor 1. A lubricant supplying mechanism is constituted of a lubricant 21, a rotary roller 22 whose surface is roughened, a spring 24 for elastically pressing the lubricant 21 on the rotary roller 22, so that a specific amount of lubricant is carried on the surface of the rotary roller 22 and a rotary brush roller 23 rotated in contact with each of the rotary roller 22 and the electrifying roller 2, to transfer the lubricant on the rotary roller 22 onto the electrifying roller 2. The electrifying roller 2 electrifies the photoreceptor 1 uniformly and transfers the lubricant supplied by the rotary brush 23 onto the photoreceptor 1, while being rotated with the photoreceptor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a lubricant supply to a photoreceptor for supplying a lubricant to a photoreceptor surface in an electrophotographic apparatus such as a copying machine, a facsimile, and a laser printer. Related to the device.

[0002]

2. Description of the Related Art As an image forming apparatus of a type in which a lubricant is applied to the surface of a photoreceptor, a photoreceptor, a charging roller which rotates in contact with the photoreceptor, and a lubricant applied to the charging roller are used. It is provided with a lubricant applied to the charging roller to improve the cleaning property, and a lubricant applied to the photoreceptor to prevent poor cleaning and filming. There is.

[0003] Supply of the lubricant to the photoreceptor as described above
Conventionally, the cleaning unit has been used, but recently, the diameter of the photoconductor has been reduced due to a tendency to save space. Therefore, the cleaning device conventionally disposed around the photoconductor is eliminated, and the residual toner that has not been transferred onto the photoconductor is moved to the developing unit with the rotation of the photoconductor, and the toner is collected in the developing unit. Cleaningless systems are attracting attention. In such a system, it is necessary to reduce the amount of residual toner more than in a system provided with another cleaning unit (in a system having a cleaning unit, a small amount of residual toner is collected by a cleaning unit, so that charging,
Although the toner does not affect the optical writing, if there is a large amount of residual toner in the cleaningless system, the area immediately below the toner is not properly charged and a latent image cannot be formed, resulting in an image defect.)

As a method of reducing the residual toner, a method is known in which a lubricant is supplied onto the photoreceptor, the adhesion between the toner and the photoreceptor is reduced, the transfer rate is improved, and the amount of the residual toner is reduced. I have. In this method, the lubricant is often supplied to the photoconductor from the cleaning unit (because excess lubricant can be collected by the cleaning unit). However, such a method cannot be adopted in a cleaningless system since there is no cleaning unit itself. Therefore, the lubricant is supplied from the charging unit. The supply of the lubricant at the charging section is unlikely to the developing section and does not adversely affect the toner. Further, the lubricant is applied to the charging member, so that the toner is hardly attached to the charging member. Further, it is possible to achieve an improvement in transfer rate (reduction of residual toner) required in a cleaningless system. Further, in the case of supply from the charging roller, the efficiency of transfer from the charging roller to the photoconductor becomes a problem. However, when the toner is in a powder form on the charging roller, the transfer can be performed efficiently.

JP-A-6-342236 (image forming apparatus) describes an example in which a lubricant is supplied from a charging roller. Thus, the normal charging roller rotates with respect to the photoreceptor. However, the lubricant does not supply well from the charging roller to the photoreceptor during the rotation, so that the linear velocity of the charging roller with respect to the photoreceptor is reduced. The lubricant can be supplied by changing the rotation speed during image formation and changing the linear velocity of the charging roller during non-image formation.

In the invention described in Japanese Patent Application Laid-Open No. 6-342236, the lubricant is smoothly transferred by changing the linear velocity during image formation and during non-image formation. If you have a speed difference instead of entourage,
The surface of the photoconductor or the charging roller is shaved and worn, which is disadvantageous for the life of the parts. Therefore, it is desirable to adopt another method as a method for smoothly transferring to the photoconductor, and to rotate as much as possible when the photoconductor and the charging roller come into contact with each other.

[0007]

Problems to be Solved by the Invention
No. 0 (image forming apparatus and image forming method) describes an example of a cleaningless system. Thus, in the cleaningless system, since there is no cleaning unit, cost reduction by reducing the number of parts can be achieved, and the residual toner can be processed without providing a special path. There is an advantage that the toner can be easily recycled by recovering the toner.

In the cleaning-less process described in Japanese Patent Application Laid-Open No. 5-210300, it is a necessary condition to minimize so-called residual toner not transferred at the transfer portion. The residual toner passes through the charging unit and the exposure unit, and is collected in the developing unit.If the amount of the residual toner is too large, for example, the surface of the photoconductor immediately below the residual toner in the charging unit may not be properly charged or may be exposed. Light does not sufficiently strike where the shadow of the toner is. As a result, a so-called afterimage occurs in which only the portion where the residual toner has been applied is toner-applied, or conversely, it is whitened. Therefore, in a cleaning-less process, the transfer efficiency is improved by using a spherical toner, and the residual toner is reduced as much as possible. However, the spherical toner has the disadvantage that the cost increases due to the spherical toner, and that the cost increase of the consumables such as the toner directly increases the running cost.

On the other hand, as a method for improving the transfer efficiency,
By transferring lubricant from the photoconductor to the paper by reducing the force acting between the photoconductor and the toner by supplying a lubricant to the photoconductor or modifying the surface of the photoconductor. There are ways to improve efficiency. Of these, the method of supplying the lubricating device is usually supplied from a cleaning unit via a cleaning brush. This means that the supply of lubricant can increase the efficiency of cleaning in the cleaning section, that excess cleaning lubricant can be removed with a cleaning blade, and that the lubricant can be applied to the surface of the photoreceptor through a brush. This is because they can be supplied efficiently. However, in a cleaningless process without a cleaning unit, a lubricant cannot be supplied from the cleaning unit. Therefore, although it is known that the transfer efficiency is improved by the supply of the lubricant, the means of supplying the lubricant has not been taken in the cleaningless process that requires the transfer efficiency to be improved.

[0010]

According to the first aspect of the present invention, there is provided a photoconductor, at least a charging roller which rotates in contact with the photoconductor and uniformly charges the surface of the photoconductor in accordance with an applied bias. An exposure device for writing an electrostatic latent image on a photoconductor,
A developing device that applies toner to the electrostatic latent image written on the photoconductor, develops the toner, and collects toner attached to a portion other than the electrostatic latent image on the photoconductor; A transfer device for transferring the toner image to the transfer object,
In an image forming apparatus in which toner remaining on a photoreceptor without being transferred to a transfer target body by the transfer device is conveyed to a developing unit with the rotation of the photoreceptor and collected by the developing unit, a lubricant in contact with the charging roller It is characterized in that the lubricant supplied by the supply device is transferred onto the photoreceptor via the charging roller, and the lubricant supplied from the lubricant supply device onto the charging roller is in powder form, Thus, in the image forming apparatus of the cleaningless system, a high-quality image without transfer failure is obtained, and further, the adverse effect of the residual toner is reduced by improving the transfer rate.

According to a second aspect of the present invention, in the first aspect of the present invention, the lubricant supply device comprises: a lubricant; a rotating roller which is pressed against the lubricant and carries a fixed amount of lubricant on a peripheral surface while rotating; A rotating brush that contacts the rotating roller and the charging roller and transfers the lubricant on the rotating roller to the charging roller, thereby efficiently supplying the powdered lubricant onto the photoreceptor. And allow the use of solid lubricant bars,
It is easier to handle and easier to assemble than a powdery lubricant.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the charging roller is separated from the lubricant supply device when the charging roller comes into contact with the photosensitive member, and the charging roller is separated from the photosensitive member. It is characterized in that it comes into contact with the lubricant supply device when it is separated, so that the toner is supplied at the time of contact where the toner accumulates at the contact portion between the photoconductor and the charging roller, so that a mixture of the toner and the lubricant can be formed. This is to prevent it.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, a charging roller cleaning member is provided on the upstream side of the lubricant supply device in the rotation direction of the charging roller. This is to prevent variations in the charging potential and defective supply of the lubricant due to sticking.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 (Invention Corresponding to Claims 1 and 2) FIG. 1 is a sectional view of a main part of an image forming apparatus utilizing the present invention. In this image forming apparatus, image formation is performed as follows. Will be First, the photoconductor 1 is uniformly charged by the charging roller 2, and then a latent image corresponding to an image to be formed is formed by the laser beam 3 in the exposure unit. Next, the latent image is developed by the developing device 4 to form a toner image. on the other hand,
The transfer paper 8 is sent out of the tray by the paper supply roller 9, temporarily stopped by the pair of registration rollers 10, and conveyed to the transfer device 5 at the same time. The toner image on the photoconductor 1 is transferred at a contact position (transfer section) between the photoconductor and the transfer paper by an electric field formed by a potential difference between the bias voltage applied to the transfer device 5 and the potential of the photoconductor 1. Transferred to paper.
The transfer paper on which the toner image has been transferred is conveyed to the fixing device 6, and
The toner is fixed and discharged. Residual toner remaining on the photoreceptor without being transferred by the transfer unit is directly collected by the developing device 4 via the charging and exposure unit as the photoreceptor 1 rotates.

Next, the lubricant supply device and the charging roller, which are main parts of the present invention, will be described in more detail. The lubricant supply device includes a lubricant 21 and the lubricant
A rotating roller 22 which is elastically pressed by the roller 4 and carries a certain amount of lubricant on its peripheral surface with rotation;
And a rotating brush roller 23 that rotates in contact with the rotating roller 22 and the charging roller 2 and transfers the lubricant on the rotating roller 22 onto the charging roller 2. The charging roller 2 uniformly charges the surface of the photoconductor 1 while rotating along with the photoconductor 1, and transfers the lubricant supplied by the rotating brush 23 onto the photoconductor.

As the lubricant 21, a dry solid lubricant is used, and typical examples thereof include the following. Zinc stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, zinc oleate, manganese oleate , Iron oleate, cobalt oleate, lead oleate, magnesium oleate, copper oleate, zinc palmitate, cobalt palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, calcium palmitate, zinc caprylate, linolenic Metal salts of fatty acids such as zinc acid, cobalt linolenate, calcium linolenate, zinc licolinonenate and cadmium licolinonenate can be used. Also, colloidal high-temperature silica powder can be used. In this embodiment, a material having a bar-like shape was used as the lubricant 21 by heating and melting zinc stearate, pouring it into a mold, and solidifying it.

FIG. 2 is a view for explaining an example of a conventional lubricating oil supply device. In the case of the conventional mechanism as shown in FIG.
, The surface of the lubricant 21 is slippery,
Since the surface of the charging roller 2 is also smooth, it is necessary to press both with a strong pressure. Then, the lubricant is formed into a thin film by the strong contact pressure and adheres to the surface of the charging roller 2.
However, in the mechanism shown in FIG. 1, the lubricant 21 is scraped off by a rotating roller 22 having a rough surface so that the lubricant 21 is gently scooped up with a brush 23 and supplied to the surface of the charging roller. Is supplied to the surface of the charging roller in powder form. Since the powdered lubricant has a smaller contact surface with the charging roller than the film-shaped lubricant, the powdered lubricant adheres to the charging roller with a weak force, so that the transfer from the charging roller to the photosensitive member can be performed smoothly. (Invention of claim 1).

Since both the lubricant on the powder and the surface of the charging roller have irregularities, the contact area becomes extremely small (the adhesion is weak) when the film is not formed. Conversely, once the film is formed, the contact area becomes extremely large (strong adhesion) because the film is formed in such a manner as to fill the unevenness of the charging roller surface.
Therefore, when the contact area between the lubricant and the charging roller is S and the volume of the lubricant is V,

[0019]

(Equation 1)

If the relationship is established, the contact area between the charging roller and the lubricant is large and the adhesive force is strong, so that the film cannot be easily transferred from the surface of the charging roller.

[0021]

(Equation 2)

If the above relationship is established, the powder may be regarded as powder.

The lubricant supply mechanism is not particularly limited as long as the lubricant is in a powdery state when supplied on the charging roller. However, in order to maintain the state of the powder, it is necessary to take measures to prevent the powder from aggregating. On the other hand, a method in which the solidified material is crushed little by little and supplied in a powder state is relatively simple and the apparatus can be made compact. Also,
There is also an advantage that the solid material does not spill as compared with the powder material, so that it is easy to handle and very easy to work when assembling to the device (the invention of claim 2).

By adopting the above-described configuration, even in a cleaning-less system, the lubricant can be supplied to the surface of the photosensitive member via the charging roller. Since it rotates, the surface of the charging roller and the photoreceptor is not roughened. In the first embodiment and the later-described embodiments 2 and 3, a description has been given of a single-color image forming apparatus having only one image forming unit.
Four image forming units are arranged along the transfer belt to create images of different colors in each image forming unit, and it goes without saying that it can be applied to color image forming equipment that is superimposed on transfer paper, and it is also directly transferred at the transfer unit Instead of transferring to paper, the image formed on the photoreceptor is sequentially transferred to an intermediate transfer body, a multicolor image is formed on the intermediate transfer body, and the color image is transferred onto the transfer paper at once. The present invention can also be applied to a color image forming apparatus.

Embodiment 2 (Invention Corresponding to Claims 1, 2 and 3) FIG. 3 is a view for explaining another embodiment of the present invention, and FIG. In this embodiment, in this embodiment, the charging roller 2 can be brought into contact with and separated from the photoreceptor 1, and when the charging roller 2 comes into contact with the photoreceptor 1, it is separated from the lubricant supply device (when it comes into contact with the photoreceptor). Away from the rotating brush)
When the charging roller 2 is separated from the photoreceptor 1, a lubricant applying mechanism 23 is disposed so as to come into contact with the lubricant supply device.

It is known that the charging of the photoreceptor 1 by the charging roller 2 is performed mainly by the discharge at the entrance side of the contact portion between the charging roller 2 and the photoreceptor 1. Therefore, FIG.
When the toner accumulates in the portion A, charging of the photoconductor is significantly inhibited. Therefore, in order to prevent toner from accumulating here, the charging roller 2 is separated from the photosensitive member 1 by a contact / separation mechanism (not shown) during non-image formation, and the toner accumulated in the portion A is removed from the developing device 4 on the downstream side. In this way, the charging of the photoreceptor 1 can always be kept uniform. However, the contact / separation operation may be performed each time during non-imaging.However, if the contact / separation operation is performed every time, the image formation speed during continuous image formation will be slow. desirable. Depending on the amount of lubricant supplied, the surface properties of the photoreceptor / charging roller, the linear velocity of the photoreceptor, the contact pressure of the charging roller with the photoreceptor, etc. Therefore, it is only necessary to repeat the minimum contact and separation during continuous image formation and perform the contact and separation operation again at the end of image formation.

When the charging roller 2 is in contact with the photoreceptor 1, toner accumulates near the contact entrance.
When the lubricant is supplied to the toner reservoir, an aggregated toner in which the toner and the lubricant are adhered to each other is formed. The aggregated toner is collected in the developing section, and a larger aggregated toner is produced in the developing section. The agglutinated toner scratches the photoreceptor, and when the photoreceptor enters the developing unit, it causes an abnormal image such as white spots. To minimize the generation of this mixture of lubricant and toner,
At the time of contact where the toner accumulates at the contact portion between the photoconductor and the charging roller, the lubricant supply device is prevented from contacting the charging roller. By doing so, it is possible to suppress the generation of the aggregated toner, and it is possible to prevent the photosensitive member from being damaged or causing an abnormal image (the invention according to claim 3).

FIG. 4 shows an example in which an eccentric cam is used as an example of the contact / separation mechanism. However, the present invention is not limited to this, and the charging roller contacts / separates the photosensitive member and the lubricant applying mechanism. Any contact / separation mechanism may be used as long as the mechanism is as described above. In FIG. 4, the bearing 31 of the charging roller 2 is shown.
Are in contact with the cam 32, and the cam 32 is connected to the half-turn clutch 33. When a signal is input to the clutch 33, the cam 32 rotates by １ ／, and the charging roller 2 together with the bearing 31 is separated from the photosensitive member 1. Also, when a signal is sent to the clutch 33 again, the cam 32 rotates again by 回 転,
The charging roller 2 comes into contact with the photoconductor 1.

Embodiment 3 (Invention Corresponding to Claims 1, 2, and 4) FIG. 5 is a sectional view of a main part around a charging roller according to still another embodiment of the present invention. If the cleaning member is not provided, the toner also adheres to the charging roller 2, so that the toner also accumulates at the entrance of the contact portion between the charging roller and the lubricant supply member 23 (N / P process). In this case, since the charging polarity of the toner and the polarity of the bias applied to the charging roller are usually both negative, it is difficult for the toner to adhere to the charging roller when the toner is normally charged. Most of the transferred toner is transferred at the transfer portion, so the residual toner that is not actually transferred contains a large amount of reverse-charged toner charged to + which is opposite to the normal polarity, and this is charged to the charging roller. Sticks) .

A mixture of toner and lubricant is also formed at the contact portion between the charging roller 2 and the lubricant supply member 23, and the mixture is conveyed to the contact portion between the charging roller 2 and the photosensitive member 1 to receive pressure. Then, agglomerated toner is generated, which damages the photoreceptor 1 or enters the developing unit, thereby causing abnormal images such as white spots. In order to avoid this, a charging roller cleaning member 25 is provided upstream of the lubricant supply member in the rotation direction of the charging roller, so that toner does not adhere to the lubricant supply member. By doing so, it is possible to suppress the generation of the aggregated toner and various problems associated therewith (the invention of claim 4). Here, the sponge blade is in contact with the charging roller, but a cleaning method such as a rubber blade or a brush roller may be used.

[0031]

As is apparent from the above description, according to the present invention, in a cleaning-less system, a lubricant is supplied without abrading the surface of a photoconductor or a charging roller, thereby improving transfer efficiency. Can be. Further, by preventing the toner from being left on the surface of the charging roller or in the vicinity of the contact portion between the charging roller and the photosensitive member, stable charging without uneven charging can be maintained. Further, since the generation of the aggregated toner can be suppressed, the generation of an abnormal image such as a white spot can be suppressed.

(Effect of Claim 1) As a method of reducing the residual toner, a lubricant is supplied onto the photoreceptor, the adhesion between the toner and the photoreceptor is weakened, the transfer rate is improved, and the residual toner is improved. Methods for reducing the amount are known.
In this method, the lubricant is often supplied to the photoreceptor from the cleaning unit (because excess lubricant can be collected by the cleaning unit). However, such a method cannot be adopted in a cleaningless system since there is no cleaning unit itself. Therefore, in the present invention, the lubricant is supplied from the charging unit. In this way, the supply of the lubricant at the charging section is less likely to adversely affect the toner than the supply at the developing section, and the lubricant is also applied to the charging member so that the toner is applied to the charging member. It becomes difficult. Further, it is possible to achieve an improvement in transfer rate (reduction of residual toner) required in a cleaningless system. Further, in the case of supply from the charging roller, the transfer efficiency from the charging roller to the photoreceptor becomes a problem. However, when the supply is in powder form on the charging roller, the transfer can be performed efficiently.

(Effect of Claim 2 of the Invention) Claim 2
According to a first aspect of the present invention, in the first aspect of the present invention, the lubricant supply device comprises: a lubricant; a rotating roller which is pressed against the lubricant and carries a certain amount of lubricant on a peripheral surface while rotating; A rotating brush that comes into contact with each of the rollers and transfers the lubricant on the rotating roller to the charging roller, whereby powdery lubricant can be efficiently supplied onto the photoreceptor. Since it is possible to use a solid lubricant bar, it is easier to handle and easier to assemble than a powdery lubricant.

(Effects Corresponding to the Invention of Claim 3) The invention of claim 3 is the invention according to claim 1 or 2, wherein the charging roller is separated from the lubricant supply device when it comes into contact with the photoconductor. When the charging roller is separated from the photoreceptor, it comes into contact with a lubricant supply device,
In this way, the lubricant is supplied at the time of contact where the toner accumulates at the contact portion between the photoconductor and the charging roller, so that a mixture of the toner and the lubricant is prevented from being formed.

That is, when the charging roller is in contact with the photosensitive member, the toner accumulates near the contact entrance.
If the lubricant is supplied simultaneously with the accumulation of the toner, an aggregated toner in which the toner and the lubricant adhere to each other is formed. The agglomerated toner is collected in the developing section and has an adverse effect in the developing section. Further, the agglomerated toner scratches the photoreceptor, and when the photoreceptor enters the developing section, it causes abnormal images such as white spots. In order to minimize the generation of the mixture of the lubricant and the toner, the lubricant supply device is prevented from contacting the charging roller when the toner accumulates at the contact portion between the photosensitive member and the charging roller. By doing so, the generation of the aggregated toner can be suppressed, and the photoconductor is not damaged and an abnormal image is not generated.

(Effects Corresponding to the Fourth Invention) According to the fourth invention, in the first or second invention, a charging roller cleaning member is provided upstream of the lubricant supply device in the rotation direction of the charging roller. This prevents variations in charging potential and poor supply of lubricant due to toner sticking to the charging roller.

When the cleaning member is not provided on the surface of the charging roller, the toner also accumulates at the entrance of the contact portion between the charging roller and the lubricant supply member. A mixture of the toner and the lubricant is also formed at the contact portion between the charging roller and the lubricant supply member, and when this is transported to the contact portion between the charging roller and the photoconductor and is subjected to pressure, aggregated toner is generated, As a result, the photoreceptor may be damaged, or it may cause an abnormal image such as white spots by entering the developing unit.However, a charging roller cleaning member is provided upstream of the lubricant supply member in the rotation direction of the charging roller. By providing the toner supply member so that the toner does not adhere to the lubricant supply member, it is possible to suppress the generation of the aggregated toner and various problems accompanying the toner.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an image forming apparatus using the present invention.

FIG. 2 is a diagram illustrating a main part mechanism of a conventional image forming apparatus.

FIG. 3 is a main part configuration diagram for explaining another embodiment of the present invention.

FIG. 4 is a view showing a contact / separation mechanism using an eccentric cam as an example of the contact / separation mechanism of the present invention.

FIG. 5 is a sectional view of a main part around a charging roller according to still another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 2 ... Charging roller, 3 ... Laser light, 4 ... Developing device, 5 ... Transfer device, 6 ... Fixing device, 8 ... Transfer paper, 9 ...
Paper feed roller, 10: registration roller, 21: lubricant, 22
... Rotating roller, 23 ... Rotating brush roller, 24 ... Spring, 25 ... Charging roller cleaning member, 31 ... Charge roller bearing, 32 ... Cam, 33 ... Rotating clutch.

Claims (4)

[Claims] 1. A photoconductor, at least a charging roller that rotates in contact with the photoconductor and uniformly charges the surface of the photoconductor according to an applied bias voltage, and an electrostatic latent image formed on the photoconductor. Exposure device for writing, and a developing device for applying toner to an electrostatic latent image written on the photoconductor, developing the electrostatic latent image, and collecting toner attached to portions other than the electrostatic latent image on the photoconductor And a transfer device for transferring the toner image on the photoreceptor to the transfer target, and the toner remaining on the photoreceptor that has not been transferred to the transfer target by the transfer device with the rotation of the photoreceptor In the image forming apparatus which is conveyed to the developing unit and collected in the developing unit, the lubricant supplied by the lubricant supply device in contact with the charging roller is transferred onto the photosensitive member via the charging roller, The charging from the lubricant supply device An image forming apparatus, wherein the lubricant supplied on the roller is in a powder form. 2. A lubricant supply device, comprising: a lubricant; a rotating roller pressed against the lubricant and carrying a certain amount of lubricant on a peripheral surface while rotating; and a rotating roller and the charging roller, respectively. 2. The image forming apparatus according to claim 1, further comprising a rotating brush for transferring a lubricant on the rotating roller to the charging roller. 3. The charging roller is separated from the lubricant supply device when the charging roller contacts the photoconductor, and contacts the lubricant supply device when the charging roller is separated from the photoconductor. The image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 1, further comprising a charging roller cleaning member upstream of the lubricant supply device in the rotation direction of the charging roller.