JP2002006689A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of elongating the life of an image carrier and also capable of enhancing picture image quality by supplying a lubricant to the image carrier forming a toner image. SOLUTION: When this image forming device previously sets the setting number of revolution (n) as the revolving speed of a photosensitive body which is needed before the surface friction factor of the photosensitive body is raised and performs image formation and the revolving speed of the body reaches the set number of revolution (n)+A (A is an integer), the device increase the transferring current of a transferring part by a prescribed quantity and rotates the body by a prescribed number of revolution without performing the image formation and it removes discharge product stuck on the surface of the body by raising temporally the friction factor of the surface of the body while increasing the recovered quantity of the lubricant of the surface of the body. When the discharge product is removed, the device returns the transferring current to a normal current value and after the friction factor of the surface of the body is made low by rotating the body by a prescribed number of revolution without performing the image formation to stick the lubricant on the surface of the body up to a suitable stuck quantity, the device performs normal image formation while applying the lubricant on the surface of the body (steps S101 to S107).

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 method of supplying a toner to an image carrier for supplying a toner to form a toner image, thereby extending the life of the image carrier.
The present invention relates to an image forming apparatus that improves image quality.

[0002]

2. Description of the Related Art In image forming apparatuses such as copying machines, printers and facsimile apparatuses using an electrophotographic system,
A uniformly charged photoreceptor (image carrier) is irradiated with writing light (exposure) modulated by image data to form an electrostatic latent image on the photoreceptor. The developing unit supplies toner to the photoreceptor on which the toner image is formed to form a toner image on the photoreceptor and develops the toner image. The image forming apparatus transfers the toner image on the photoreceptor to recording paper at a transfer unit, and then heats and presses the toner transferred on the recording paper at a fixing unit to fix the toner, thereby cleaning the toner remaining on the photoreceptor surface. It is collected by a method such as scraping with a cleaning blade at the section.

As described above, when the cleaning blade scrapes off the toner remaining on the surface of the photoreceptor, a high frictional force between the cleaning blade and the photoreceptor causes blade friction and abrasion of the film on the surface of the photoreceptor. This was the cause of shortening the service life.

In an image forming apparatus using such an electrophotographic system, a lubricant is conventionally applied to the surface of a photoreceptor to reduce the coefficient of friction on the surface of the photoreceptor.
It prevents unnecessary toner from adhering, forms an image free from background contamination, and applies and scrapes a lubricant to constantly refresh the surface of the photoconductor and extend the life of the photoconductor. ing. Further, when the lubricant is applied to the surface of the photoreceptor, there is an effect that the amount of toner adhering to the non-image portion of the photoreceptor can be reduced, the toner can be effectively used, and resources can be saved.

In particular, in an image forming apparatus in which a cleaning section removes residual toner on the surface of a photoreceptor with a cleaning blade, when a lubricant is supplied onto the photoreceptor, when the surface of the photoreceptor is cleaned by the cleaning blade, And the coefficient of friction of the cleaning blade is reduced, and the life of the photoconductor can be extended.

That is, the cause of determining the life of the photoreceptor is abrasion of the photoreceptor layer of the photoreceptor. When a certain amount of the photoreceptor layer is removed, the electrical characteristics of the photoreceptor change and an appropriate image is formed. The process cannot be performed. This friction occurs in the image forming process in all areas where the photoconductor and other image forming units such as a developing unit and a transfer unit come into contact with each other, but the most problematic is the residual toner on the photoconductor. It is a cleaning blade that is mechanically removed. Although it is worn by other parts, it does not affect the actual life.

However, when the frictional action on the photoreceptor is small, a large amount of ozone is generated with the discharge in the charging step,
Nitrogen in the air is oxidized to generate nitrogen oxides (NOx), and the nitrogen oxides react with moisture in the air to produce nitric acid and the like. When these discharge products adhere to or act on the photoreceptor surface and cause deterioration, deterioration, etc., it becomes difficult to remove them with a cleaning blade, lowering the electrical characteristics of the photoreceptor surface, reducing image blur. There is a problem that this may cause the image quality to deteriorate.

That is, in the above-described conventional method, when the surface of the photoconductor is reduced in friction to reduce the abrasion of the photoconductor and prolong the service life, the discharge products adhered to the surface of the photoconductor cannot be removed. There has been a problem that image blur occurs, and if the surface of the photoconductor is shaved to prevent image blur, a long life of the photoconductor cannot be realized.

Therefore, conventionally, a charging roller which comes into pressure contact with the image carrier and rotates therewith, a lubricant applying roller which comes into pressure contact with the image carrier and is driven via a clutch, and a lubricant applying roller which passes through the lubricant applying roller. A lubricant supply unit for supplying a lubricant to the image carrier; a detection unit for engaging with the charging roller and / or the lubricant application roller to detect a rotational driving state; and the clutch based on a detection signal of the detection unit. There has been proposed a lubricant application control device in an image forming apparatus, which is provided with a control means for performing on / off control of the lubricant (see JP-A-8-305236).

Conventionally, at least an electrophotographic photosensitive member and a charging member arranged in contact or non-contact with the photosensitive member are used, and the photosensitive member is charged by discharging in a minute space by applying a voltage from the charging member. In the image forming method, the photoreceptor has a photosensitive layer on a conductive support,
An image forming method has been proposed in which at least the layer farthest from the support contains at least one of an antioxidant and an ultraviolet absorber (Japanese Patent Application Laid-Open No. 7-2).
95246).

[0011]

However, in the lubricant application control device in the image forming apparatus described in Japanese Patent Application Laid-Open No. 8-305236, the amount of lubricant supplied is controlled to reduce image blur. Trying to prevent it,
The causal relationship between image blur and lubricant supply is not clear,
Further, there is no description of specific means for image blur due to generation of NOx due to insufficient wear of the photoconductor.

Therefore, in this conventional method, since the amount of lubricant supplied to the photosensitive member is controlled to be constant, the friction coefficient on the photosensitive member is always constant, and the image is stable. When the friction coefficient on the photoreceptor is reduced, there is a problem that the shaving amount of the photoreceptor decreases and image blur occurs with time.

In the image forming method described in JP-A-7-295246, the life of the photoconductor is extended by incorporating an antioxidant and a fluororesin powder inside the layer of the photoconductor. However, if the photoreceptor side does not wear at all, the effect of the antioxidant gradually decreases, and as a result, image blurring due to accumulation of low-resistance substances cannot be eliminated, and the effect of the antioxidant is maintained. Therefore, there is a problem that the effect of extending the life of the photoconductor is lost even if the photoconductor is shaved for the purpose.

Therefore, according to the first aspect of the present invention, the image carrier to which the lubricant is supplied by the lubricant supplying means and the friction is reduced is uniformly charged by the charging means, and the uniformly charged image carrier is charged. The image carrier is irradiated with exposure modulated based on image data to form an electrostatic latent image, and toner is supplied to the image carrier on which the electrostatic latent image is formed to form a toner image. When the toner image on the image carrier is transferred to recording paper, and the residual toner on the image carrier after the toner image is transferred onto the recording paper is removed by the cleaning unit, the image carrier is transferred at a predetermined time by the friction increasing unit. By temporarily increasing the coefficient of friction of the surface, the surface friction coefficient of the image carrier is reduced during normal image formation with a simple configuration, thereby extending the life of the image carrier inexpensively and reducing discharge products. Before image blur occurs, surface friction of the image carrier Provided is an image forming apparatus that temporarily increases the number to remove discharge products from the surface of the image carrier to avoid image blur and prevent image deterioration, and to keep image quality constant and avoid image blur. It is intended to be.

According to a second aspect of the present invention, the image bearing member is temporarily increased in friction coefficient on the surface of the image bearing member by friction increasing means at a predetermined time when the image bearing member has rotated to a predetermined rotational speed. Is used up to the number of revolutions before image blur occurs due to discharge products attached to the surface, temporarily increasing the surface friction coefficient of the image carrier to remove the discharge products from the image carrier surface It is an object of the present invention to provide an image forming apparatus that avoids image blur by preventing image blur and prevents image blur while maintaining a constant image quality.

According to a third aspect of the present invention, the image bearing member adheres to the surface by temporarily increasing the friction coefficient of the surface of the image bearing member by the friction increasing means at a predetermined time when a predetermined time has elapsed. When used until the time before image blur occurs in the discharge product, the surface friction coefficient of the image carrier is temporarily increased to remove the discharge product from the image carrier surface to avoid image blur. It is an object of the present invention to provide an image forming apparatus that prevents image deterioration and avoids image blur while maintaining a constant image quality.

According to a fourth aspect of the present invention, when the power supply of the image forming apparatus is turned on as a predetermined time, the friction coefficient of the surface of the image carrier is temporarily increased by the friction increasing means, so that the image forming apparatus can be used. Each time the power is turned on, the surface friction coefficient of the image carrier is temporarily increased to remove discharge products from the surface of the image carrier, avoid image blur, prevent image degradation, and improve image quality. It is an object of the present invention to provide an image forming apparatus that avoids image blur while keeping the image constant.

According to a fifth aspect of the present invention, the friction coefficient of the surface of the image carrier is temporarily increased by the friction increasing means when the image formation is not performed or the image formation is temporarily interrupted. Thereby, image formation is performed in a state in which the surface friction coefficient of the image carrier is temporarily increased, preventing formation of an image with poor image quality, and further appropriately maintaining image quality constantly. It is an object of the present invention to provide an image forming apparatus that avoids image blur.

According to a sixth aspect of the present invention, by using polytetrafluoroethylene as a lubricant, the surface friction coefficient of the image bearing member can be temporarily increased, and the transition to low friction can be quickly performed. An object of the present invention is to provide an image forming apparatus capable of further reducing the wear amount of an image carrier, further extending the life of the image carrier, and further improving image quality.

[0020]

According to the first aspect of the present invention, there is provided an image forming apparatus wherein an image carrier to which a lubricant is supplied by a lubricant supply unit and whose friction is reduced is uniformly charged by a charging unit. Irradiating the uniformly charged image carrier with exposure modulated based on image data to form an electrostatic latent image, and applying toner to the image carrier having the electrostatic latent image formed thereon. The toner image is supplied to form a toner image, the toner image on the image carrier is transferred to a recording sheet, and the residual toner on the image carrier after the toner image is transferred to the recording sheet is removed by a cleaning unit. The above object is attained by providing a friction increasing means for temporarily increasing the friction coefficient of the surface of the image carrier at a predetermined time in an image forming apparatus.

According to the above arrangement, the image carrier to which the lubricant is supplied by the lubricant supply unit and whose friction is reduced is uniformly charged by the charging unit, and the uniformly charged image carrier is charged onto the image carrier. An electrostatic latent image is formed by irradiating exposure modulated based on image data, and toner is supplied to the image carrier on which the electrostatic latent image has been formed to form a toner image. When the toner image is transferred to a recording sheet and the residual toner on the image carrier after the toner image is transferred to the recording sheet is removed by the cleaning unit, the friction coefficient of the surface of the image carrier at a predetermined time by the friction increasing unit. Is temporarily raised, the surface friction coefficient of the image carrier can be reduced during normal image formation with a simple configuration, and the life of the image carrier can be lengthened inexpensively. Before image blur occurs, the surface friction of the image carrier Can be temporarily increased to remove discharge products from the surface of the image carrier to avoid image blur and prevent image deterioration, and to avoid image blur while maintaining a constant image quality. .

In this case, for example, in the image forming apparatus, the image carrier is rotated by the friction increasing means when the rotation of the image carrier to a predetermined number of revolutions is the predetermined time. The friction coefficient of the surface may be temporarily increased.

According to the above configuration, the friction coefficient of the surface of the image carrier is temporarily increased by the friction increasing means at the predetermined time when the image carrier has rotated to the predetermined number of revolutions.
When the image carrier is used up to the rotation speed before the image blur occurs due to the discharge product adhered to the surface, the surface friction coefficient of the image carrier is temporarily increased to discharge the discharge product from the image carrier surface. It is possible to prevent the image from being degraded by removing the image blur, and to prevent the image blur while keeping the image quality constant.

Further, for example, the image forming apparatus may use the friction increasing means to temporarily set the coefficient of friction of the surface of the image carrier as a predetermined time when a predetermined time has elapsed. May be raised.

According to the above arrangement, the friction coefficient of the surface of the image carrier is temporarily increased by the friction increasing means at a predetermined time when a predetermined time has elapsed. If the product is used until the time before image blur occurs, the surface friction coefficient of the image carrier is temporarily increased to remove discharge products from the image carrier surface to avoid image blur and to reduce image blur. Can be prevented from deteriorating, and image blur can be avoided while keeping the image quality constant.

Further, for example, in the image forming apparatus, the time when the power of the image forming apparatus is turned on is set as the predetermined time, and the surface of the image carrier is moved by the friction increasing means. The coefficient of friction may be temporarily increased.

According to the above configuration, the friction coefficient on the surface of the image carrier is temporarily increased by the friction increasing means when the power of the image forming apparatus is turned on as a predetermined time. Each time is turned on, the surface friction coefficient of the image carrier is temporarily increased, discharge products are removed from the surface of the image carrier, image blur is avoided, and image deterioration can be prevented. Image blur can be avoided while maintaining a constant quality.

Further, for example, when the image forming apparatus is not performing the image forming, or in a state in which the image forming is temporarily interrupted, the image forming apparatus may use the friction increasing means. The friction coefficient of the surface of the image carrier may be temporarily increased.

According to the above arrangement, the friction coefficient of the surface of the image carrier is temporarily increased by the friction increasing means when image formation is not performed or when image formation is temporarily interrupted. The image is formed in a state where the surface friction coefficient of the image carrier is temporarily increased, and it is possible to prevent the formation of an image with poor image quality, and to more appropriately keep the image quality constantly constant. Moreover, image blur can be avoided.

Further, for example, as described in claim 6, the lubricant may be polytetrafluoroethylene.

According to the above configuration, since polytetrafluoroethylene is used as the lubricant, the surface friction coefficient of the image carrier is temporarily increased, and the transition to low friction is quickly performed, so that The wear amount of the carrier can be further reduced, the life of the image carrier can be further extended, and the image quality can be further improved.

[0032]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 7 show an image forming apparatus to which an embodiment of the image forming apparatus of the present invention is applied, and FIG. 1 shows an embodiment of the image forming apparatus of the present invention. 1 is a schematic configuration diagram of a main part of an image forming apparatus 1 according to the present invention.

In FIG. 1, an image forming apparatus 1 includes a charging unit 3, an optical writing unit (not shown), a developing unit 4, a transfer unit 5, a cleaning unit 6, and a charge removing unit around a photosensitive member (image carrier) 2. 7 and the like, and a fixing unit (not shown) is provided. As shown by an arrow in FIG.
It is driven to rotate clockwise.

The image forming apparatus 1 has a paper feed cassette (not shown) for accommodating a plurality of recording papers 8, and the recording papers 8 in the paper feed cassette are fed by a paper feed roller (not shown).
Each sheet is sent out to a pair of registration rollers (not shown), the timing is adjusted by the pair of registration rollers, and then sent out between the transfer unit 5 and the photoconductor 2.

A charging section (charging means) 3 uniformly charges the photosensitive member 2, and an optical writing section (not shown) modulates the photosensitive member 2 charged by the charging section 3 with laser light (modulated by image data). (Exposure) 9 to form an electrostatic latent image.

The developing unit 4 contains a developer in a developing unit 10, and a photoconductor on which an electrostatic latent image is formed by a developing roller 11 provided in the developing unit 10 with toner of the developer. The electrostatic latent image on the surface of the photoconductor 2 is visualized and developed as a toner image. The developer in the developing unit 10 is supplied to the developing roller 11 by a supply roller 12 housed in the developing unit 10.

The developer may be a two-component developer composed of a carrier and a toner, or a one-component developer composed of only a toner containing no carrier.

The transfer section 5 applies a transfer bias to apply the toner image formed on the photoconductor 2 by the developing section 4 to the recording paper 8 conveyed between the registration roller pair and the photoconductor 2. The image forming apparatus 1 transfers the recording paper 8 onto which the toner image has been transferred to a fixing unit (not shown).

The fixing unit generally includes a fixing roller heated to a predetermined fixing temperature by a built-in heater, and a pressure roller pressed against the fixing roller at a predetermined pressure.
After the recording paper 8 conveyed from the printer is heated and pressed to fix the toner image on the recording paper 8 to the recording paper 8, the recording paper 8 is discharged onto a discharge tray (not shown).

The cleaning section 6 includes a cleaning case 13, a cleaning brush 14, a cleaning blade 15, a waste toner conveying screw 16, and the like.
The cleaning unit 6 disturbs the waste toner remaining on the photoconductor 2 after the transfer by the cleaning brush 14 rotating clockwise (the direction opposite to the rotation direction of the photoconductor 2).
After the removal, it is scraped off with the cleaning blade 15 and removed, and stored in the cleaning case 13.
The cleaning unit 6 transports the waste toner stored in the cleaning case 13 to a waste toner storage unit (not shown) by a waste toner transport screw 16.

The static elimination unit 7 includes a static elimination lamp (not shown), and irradiates the photosensitive member 2 cleaned by the cleaning unit 6 with static elimination light to neutralize the photosensitive member 2 and average it to a reference potential.

That is, the image forming apparatus 1 drives the photosensitive member 2 to rotate clockwise as shown by the arrow in FIG. Irradiates a laser beam 9 modulated with image data by the photoconductor 2
Photoreceptor 2 on which an electrostatic latent image is formed
And a developing unit 10 in the developing unit 4 by a developing roller 11.
The toner of the developer inside is adhered and developed. The image forming apparatus 1 causes the transfer unit 5 to transfer the photoconductor 2 on which the toner is adhered to form a toner image in the developing unit 4 to the recording paper 8 conveyed between the photoconductor 2 and the transfer unit 5. Then, the recording paper 8 on which the toner image has been transferred is conveyed to a fixing unit, and the recording paper 8 is heated and pressed by the fixing unit to fix the toner image on the recording paper 8 to the recording paper 8, and then not shown. Discharge to the output tray.

The image forming apparatus 1 further rotates the photosensitive member 2 on which the toner image has been transferred onto the recording paper 8 by the transfer unit 5, and remains on the surface of the photosensitive member 2 by the cleaning brush 14 and the cleaning blade 15 of the cleaning unit 6. The removed toner is scraped off, and the cleaned photoreceptor 2 is neutralized by the neutralizing unit 7 and then uniformly charged by the charging unit 3 to be subjected to the next image formation in the same manner as described above.

Then, a predetermined lubricant is supplied to the photosensitive member 2 to reduce the friction coefficient μ of the surface of the photosensitive member 2 (the surface friction coefficient μ of the photosensitive member 2). Various methods can be used to supply the lubricant to the photoconductor 2. For example, as shown in FIG. 2, a lubricant application section (lubricant supply means) 20 is provided between the cleaning section 6 and the charge removing section 7, and the cleaning section 6 performs cleaning by the lubricant application section 20. The lubricant 21 may be applied to the surface of the photoconductor 2.

The lubricant applying section 20 holds the lubricant 21 by the holder 22 and presses the lubricant 21 to the surface of the photoreceptor 2 with a predetermined pressure by an elastic member 23 such as a spring via the holder 22. Then, the lubricant 21 is applied to the surface of the rotating photoconductor 2. When the lubricant 21 is applied to the photoreceptor 2 by the lubricant application unit 20, a layer of the lubricant 21 is formed on the surface of the photoreceptor 2. As the lubricant 21, a solid substance or a substance having a sheet-like lubricating property can be used, and as the type of the lubricant 21, various substances such as a fluorine-based material and zinc stearate can be used.

As a method for supplying the lubricant to the photosensitive member 2, as shown in FIG. 3, a lubricant application section (lubricant supply means) 3 is provided in the cleaning case 13 of the cleaning section 6.
Alternatively, the lubricant 31 may be applied to the cleaning brush 14 by the lubricant application section 30, and the lubricant 31 applied to the cleaning brush 14 may be applied to the surface of the photoconductor 2.

The lubricant application section 30 holds the lubricant 31 with the holder 32 and the holder 32 with the cleaning case 1.
The cleaning brush 14 is disposed at a position facing the cleaning brush 14 in a state where the cleaning brush 14 contacts the lubricant 31. The lubricant applying section 30 scrapes the lubricant 31 with the rotating cleaning brush 14 and
The lubricant 31 adheres to the surface of the photoconductor 2 when the cleaning brush 14 to which the lubricant 31 adheres comes into contact with the surface of the photoconductor 2. Thus, a layer of the lubricant 31 is formed on the surface of the photoconductor 2.

The method of supplying the lubricant to the photoreceptor 2 is not limited to the above two methods. The lubricant is appropriately supplied to the surface of the photoreceptor 2 so that the lubricant layer is formed. 2
Any method may be used as long as it can be formed on the surface, and for example, a method in which a lubricant is added to the developer and supplied to the surface of the photoconductor 2 may be used.

When the lubricant is supplied to the surface of the photosensitive member 2 in this manner, the surface friction coefficient μ of the photosensitive member 2 is reduced.
When the surface friction coefficient μ of the photoconductor 2 decreases and the wear amount of the photoconductor 2 decreases, the life of the photoconductor 2 can be prolonged. A large amount of ozone is generated with the discharge in the process, and oxidizes nitrogen in the air to produce nitrogen oxides (NOx).
Or the nitrogen oxides react with moisture in the air to produce nitric acid and the like. These discharge products adhere to or act on the surface of the photoreceptor 2 to alter the surface of the photoreceptor 2,
Deterioration and the like are caused, and the surface of the photoconductor 2 is electrically reduced in resistance, which appears as a phenomenon of image blur. This phenomenon becomes remarkable under a high temperature and high humidity environment.

Such a phenomenon does not occur immediately when the surface of the photoreceptor 2 is made to have low friction. And appears as a phenomenon of image blur.

In order to realize a stable image output, it is necessary to remove the discharge products attached to the surface of the photosensitive member 2. This discharge product can be mechanically removed by the cleaning blade 15 or the like when the surface friction coefficient μ of the photoreceptor 2 becomes higher than a certain friction coefficient.

According to experiments conducted by the present applicant, the amount of wear of the photosensitive member 2 is found to be proportional to the surface friction coefficient μ of the photosensitive member 2 as shown in FIG.

The lubricants 21 and 31 supplied to the surface of the photoreceptor 2 are mechanically or electrically recovered while passing through the developing unit 4 and the transfer unit 5. The recovery amount of 31 depends on and is determined by the system around the photoreceptor 2, and if the same system, the fluctuation of the recovery amount is small. Then, in order to reduce the surface friction coefficient μ of the photoconductor 2, it is necessary to increase the supply amount of the lubricants 21 and 31 to be larger than the recovery amount.

Therefore, for each image forming apparatus 1, the amount of the lubricant collected in the image forming apparatus 1 is grasped by an experiment or the like, and the surface friction coefficient μ of the photosensitive member 2 is set to an intended value as described later. Therefore, the supply amount of the lubricant is adjusted to an appropriate amount.

Further, in the case of the supply method shown in FIG. 3, for example, the supply amount of the lubricant can be changed by setting the bite amount and the nip width between the lubricant 31 and the cleaning brush 14.

On the other hand, the surface friction coefficient μ of the photoreceptor 2 can be increased by increasing the amount of the lubricant to be supplied to the photoreceptor 2 more than the supply amount of the lubricant.
For example, the pressing force of the member supplying the lubricants 21 and 31 may be reduced to reduce the supply amount of the lubricants 21 and 31;
A method of increasing the amount of lubricant 21, 31 recovered from the surface,
Surface potential of photoconductor 2 immediately before charging and photoconductor 2 after charging
A method of increasing the amount of the lubricants 21 and 31 to be electrically recovered by increasing the potential difference of the surface potentials of the lubricants, or a method of increasing the amount of the lubricants 21 and 31 recovered by increasing the transfer bias by the transfer unit 5. Can be used.

The image forming apparatus 1 uses the lubricant 2
By appropriately controlling the supply and recovery of the photoconductors 1 and 31, the life of the photoconductor 2 is extended and the image quality is improved.

Next, the operation of the present embodiment will be described. The image forming apparatus 1 is characterized in that the supply and recovery of the lubricants 21 and 31 of the photoconductor 2 are appropriately controlled to extend the life of the photoconductor 2 and improve the image quality. .

That is, the image forming apparatus 1 rotates the photoconductor 2 clockwise in FIG. 1 and uniformly charges the photoconductor 2 with the charging unit 3 as described above during image formation. The optical writing unit irradiates a laser beam 9 modulated with image data to form an electrostatic latent image on the photoconductor 2, and the developing unit 4 applies a developing roller 11 to the photoconductor 2 on which the electrostatic latent image is formed. The toner of the developer in the developing unit 10 is caused to adhere to the developing unit 10 for development. The image forming apparatus 1 causes the transfer unit 5 to transfer the photoconductor 2 on which the toner is adhered to form a toner image in the developing unit 4 to the recording paper 8 conveyed between the photoconductor 2 and the transfer unit 5. Then, the recording paper 8 on which the toner image has been transferred is conveyed to a fixing unit, and the recording paper 8 is heated and pressed by the fixing unit to fix the toner image on the recording paper 8 to the recording paper 8, and then not shown. Discharge to the output tray.

On the other hand, the image forming apparatus 1 further rotates the photoreceptor 2 on which the toner image has been transferred to the recording paper 8 by the transfer unit 5, and uses the cleaning brush 14 and the cleaning blade 15 of the cleaning unit 6 to apply the light After the toner remaining on the surface is scraped off and removed, and the charge is removed by the charge removing unit 7, the photoreceptor 2 is uniformly charged by the charging unit 3, and the next image is formed in the same manner as described above.

The image forming apparatus 1 applies the lubricant 2 to the photosensitive member 2 by the supply method shown in FIG.
1 and 31, and the photoreceptor 2 has lubricants 21 and 3
1, the friction coefficient μ of the surface of the photoconductor 2 is reduced, and the photoconductor 2 and other members disposed around the photoconductor 2, in particular, the cleaning blade 1 of the cleaning unit 6
5 can be reduced, the life of the photoconductor 2 can be improved, and the image quality can be improved.

That is, the lubricant 21, 3
When the cleaning blade 15 is not applied, the sliding pressure between the cleaning blade 15 and the photoreceptor 2 increases, so that a noise is generated due to friction between the cleaning blade 15 and the photoreceptor 2 and the surface of the photoreceptor 2 is worn. Is promoted, the life of the photoconductor 2 is shortened, and the image quality is deteriorated.

Therefore, the lubricants 21 and 31 are applied to the surface of the photoreceptor 2.
Is applied, and the supply amounts of the lubricants 21 and 31 are set so that the surface friction coefficient μ of the photoconductor 2 becomes an appropriate friction coefficient based on the relationship between the photoconductor wear amount and the friction coefficient μ shown in FIG. .

Therefore, in this embodiment, the lubricants 21 and 31 are adhered to the surface of the photoconductor 2 by the above-described method so that the friction coefficient μ of the surface of the photoconductor 2 becomes an appropriate friction coefficient.

At this time, the lubricant 2 adhering to the photosensitive member 2
In order to determine the amounts of the lubricants 1 and 31, the friction coefficients of the surface of the photoconductor 2 are measured by a predetermined method, for example, the Euler belt method shown in FIG.

In the Euler belt method, as shown in FIG.
Measurement table 41 fixed to one end of measurement table 40
The digital force gauge 42 is arranged on the upper side, and the photoreceptor 2 to be measured is set on the photoreceptor mounting table 43 provided at the other end of the measurement table 40. A belt 44 is disposed at a portion in contact with the photoconductor 2, one end of the belt 44 is connected to the digital force gauge 42 via a hook or the like, and a predetermined weight, for example, is connected to the other end of the belt 44 via a hook or the like. , 100 g of load 45 in a state where gravity is appropriately applied. That is, in the Euler belt method, the digital force gauge 42 is connected in the horizontal direction via the cylindrical photoreceptor 2, and the load 45 is connected in the vertical direction bent at 90 degrees.

In this state, the digital force gauge 42
To read the value F indicated by the digital force gauge 42 at the time when the belt 44 starts moving, and calculate the friction coefficient μ of the surface of the photoconductor 2 by the following equation (1).
The coefficient of friction μ of the surface of the photoconductor 2 is measured.

Μ = In (F / W) / (π / 2) (1) In the image forming apparatus 1, the friction coefficient μ of the surface of the photoconductor 2 measured in this manner is within an appropriate range. The supply amounts of the lubricants 21 and 31 are set so that The coefficient of friction μ of the surface of the photoreceptor 2 to which the lubricants 21 and 31 were not applied was measured by the Euler belt method.
It was about 0.6.

The setting of the supply amounts of the lubricants 21 and 31 is as follows.
For example, in the case of the supply method shown in FIG. 3, as described above, the supply amount can be changed by setting the amount of bite between the lubricant 31 and the cleaning brush 14 and the nip width.

The lubricants 21 and 31 supplied to the surface of the photoreceptor 2 are mechanically or electrically collected while passing through the developing unit 4 and the transfer unit 5 as described above. The recovery amount of the lubricants 21 and 31 depends on and is determined by the system around the photoreceptor 2, and the recovery amount of the same system is small. In order to reduce the surface friction coefficient μ of the photoconductor 2, the lubricants 21 and 31
Needs to be set in consideration of the recovery amount.

Therefore, for each image forming apparatus 1, the amount of the lubricants 21 and 31 recovered in the image forming apparatus 1 is grasped by an experiment or the like, and the supply amount of the lubricants 21 and 31 is adjusted to an appropriate amount. .

The lubricant 2 supplied to the photosensitive member 2
Reference numerals 1 and 31 denote photosensitive members 2 as the image forming process is performed.
As shown by a solid line in FIG. 6, the friction coefficient μ decreases as the number of prints (the number of images formed) increases, as shown by the solid line in FIG. In FIG. 6, a broken line indicates a change in the friction coefficient μ with respect to the number of PTFE (polytetrafluoroethylene) prints.

However, as described above, when the surface friction coefficient μ of the photosensitive member 2 decreases and the wear amount of the photosensitive member 2 decreases,
Although the life of the photoconductor 2 can be prolonged, when the abrasion action on the photoconductor 2 is small, a large amount of ozone is generated due to the discharge in the charging step and the transfer step, and nitrogen in the air is generated as described above. Is oxidized to generate nitrogen oxides (NOx), and the nitrogen oxides react with moisture in the air to produce nitric acid and the like. These discharge products adhere to or act on the surface of the photoreceptor 2, causing deterioration or deterioration of the surface of the photoreceptor 2, causing the surface of the photoreceptor 2 to have a low electrical resistance and causing a phenomenon of image blur. Appear as. This phenomenon becomes remarkable under a high temperature and high humidity environment.

Such a phenomenon does not occur immediately when the surface of the photoreceptor 2 is made to have a low friction. And appears as a phenomenon of image blur.

Therefore, the image forming apparatus 1 of the present embodiment
, Temporarily collects the lubricants 21 and 31 on the surface of the photoconductor 2 based on the rotation speed of the photoconductor 2 to increase the surface friction coefficient μ of the photoconductor 2 and generate discharges such as nitrogen oxides. The attached matter is removed from the surface of the photoreceptor 2 to prevent image blur.

That is, as shown in FIG. 7, the image forming apparatus 1 sets the number of rotations of the photosensitive member 2 before the surface friction coefficient μ of the photosensitive member 2 is increased to a set number n, for example, n = 30.
0 (step S101), image formation is performed,
It is checked whether the number of rotations of the photoconductor 2 has reached a set number of times n + A (A is an integer) (step S102). Note that, even if image formation is performed continuously, the set number of rotations n may cause image blurring due to electrical resistance reduction of the surface of the photoconductor 2 due to discharge products such as nitrogen oxides attached to the surface of the photoconductor 2. Set the rotation speed within the range where does not occur. The set number of rotations n before the occurrence of the image blur differs depending on the system around the photoreceptor 2, but if the system is the same, there is little variation and the life is short until the life of the main body of the image forming apparatus 1. If so, the initially set values can be used as they are. Further, it is preferable that the set number of revolutions n is determined by an experiment. However, it is more preferable to determine the set rotation number by an experiment in a high-temperature and high-humidity environment where image blur is likely to occur in order to ensure safety. It is.

In step S102, if the rotation speed of the photosensitive member 2 has not reached the set rotation speed n + A, the image forming apparatus 1
Performs normal image formation while applying the lubricants 21 and 31 as they are (step S107).

In step S102, if the rotation speed of the photosensitive member 2 has reached the set rotation speed n + A, the image forming apparatus 1
A temporary increase process of the surface friction coefficient μ of the photoconductor 2 is performed (steps S103 to S106), and thereafter, the lubricants 21 and 31 are used.
A normal image formation is performed while applying the ink (step S10).
7). In the process of temporarily increasing the surface friction coefficient μ of the photoconductor 2, for example, the transfer current is increased to increase the amount of the lubricants 21 and 31 collected on the surface of the photoconductor 2 to increase the surface friction coefficient μ of the photoconductor 2. In order to increase the transfer speed, first, the transfer current of the transfer unit 6 is increased by a predetermined amount (step S103), and the photoconductor is not formed without performing image formation, that is, with the image forming apparatus 1 set to downtime. 2 is the predetermined number of revolutions,
For example, by rotating 10 times, discharge products such as nitrogen oxides adhering to the surface of the photoconductor 2 are removed (step S10).
4). The number of rotations of the photoreceptor 2 is set to a number necessary and sufficient for removing discharge products due to an increase in transfer current.

When the photoreceptor 2 is rotated to remove discharge products, the image forming apparatus 1 returns the transfer current to a normal current value (step S105), and rotates the photoreceptor 2 for a predetermined rotation without forming an image. After a number of rotations, for example, ten, the lubricants 21 and 31 are adhered to the surface of the photoreceptor 2 to a suitable amount (step S106). The number of rotations of the photoconductor 2 is set to a number necessary and sufficient for applying the lubricants 21 and 31 to make the photoconductor 2 have a suitable low friction coefficient μ.

When the friction of the surface of the photosensitive member 2 is reduced, the image forming apparatus 1 forms a normal image while applying the lubricants 21 and 31 (step S107).

Then, when the present applicant applied a lubricant to the photoreceptor 2 using various lubricants and measured the friction coefficient μ by the Euler belt method, as shown in FIG. It has been found that the coefficient of friction μ decreases fastest in relation to the number of rotations (number of prints) of the photoreceptor 2, and the coefficient of friction μ increases fastest by applying a lubricant. Therefore, as a lubricant used in the present invention, PT
FE has been found to be the most suitable.

As described above, in the image forming apparatus 1 of the present embodiment, the photosensitive member 2 to which the lubricants 21 and 31 are supplied by the lubricant applying section 20 or the lubricant applying section 30 to reduce the friction is charged. Exposure 9 that is uniformly charged by the unit 7 and modulated on the uniformly charged photoconductor 2 based on image data
To form an electrostatic latent image, supply toner to the photoreceptor 2 on which the electrostatic latent image is formed to form a toner image, and transfer the toner image on the photoreceptor 2 to recording paper 8 Then, when the cleaning unit 6 removes the residual toner on the photoconductor 2 after transferring the toner image to the recording paper 8, the friction coefficient μ of the surface of the image carrier is temporarily increased at a predetermined time.

Therefore, during normal image formation with a simple structure, the surface friction coefficient μ of the photosensitive member 2 can be reduced to extend the life of the photosensitive member 2 at low cost, and image blurring occurs due to discharge products. Before the discharge, the surface friction coefficient μ of the photoreceptor 2 is temporarily increased to remove discharge products from the surface of the photoreceptor 2, avoid image blurring, prevent image deterioration, and maintain a constant image quality. Image blur can be avoided while maintaining the image quality.

The image forming apparatus 1 according to the present embodiment
Based on the number of rotations of the photoconductor 2, the friction coefficient on the surface of the photoconductor 2 is temporarily increased to remove discharge products such as nitrogen oxides from the surface of the photoconductor 2.

Therefore, when the photoreceptor 2 is used up to the number of rotations before the image blur occurs due to the discharge product adhering to the surface, the surface friction coefficient μ of the photoreceptor 2 is temporarily increased to increase the discharge product. Can be removed from the surface of the photoreceptor 2 to prevent image blurring and prevent image degradation, and to avoid image blurring while maintaining a constant image quality.

Further, the image forming apparatus 1 of the present embodiment
Indicates that the surface friction coefficient μ of the photoreceptor 2 is not being formed or the image formation is temporarily interrupted.
Is temporarily raised.

Therefore, image formation is performed in a state where the surface friction coefficient μ of the photosensitive member 2 is temporarily increased, so that it is possible to prevent formation of an image having poor image quality, and to more appropriately perform image quality Can be avoided while always keeping the constant.

In the above-described embodiment, the friction coefficient of the surface of the photoconductor 2 is temporarily increased based on the rotation speed of the photoconductor 2 so that discharge products such as nitrogen oxides are discharged from the surface of the photoconductor 2. Is removed, but is not limited to the one based on the number of rotations of the photoconductor 2, and may be performed, for example, every predetermined time.

In this way, when the photosensitive member 2 is used up to the time before the image blur occurs due to the discharge products adhered to the surface, the surface friction coefficient μ of the photosensitive member 2 is temporarily increased to discharge. The product can be removed from the surface of the photoreceptor 2 to prevent image blur by preventing image blur, and to avoid image blur while keeping image quality constant.

When the power of the image forming apparatus 1 is turned on, the friction coefficient of the surface of the photosensitive member 2 is temporarily increased at the time of startup of the image forming apparatus 1 so that discharge products such as nitrogen oxides are discharged from the surface of the photosensitive member 2. Removal may be performed.

In this manner, every time the power supply of the image forming apparatus 1 is turned on, the surface friction coefficient μ of the photosensitive member 2 is temporarily increased to remove the discharge products from the surface of the photosensitive member 2 and to remove the image blur. Thus, it is possible to prevent deterioration of the image and prevent image blurring while keeping the image quality constant.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

[0094]

According to the image forming apparatus of the first aspect of the present invention, the image carrier to which the lubricant is supplied by the lubricant supplying means and the friction is reduced is uniformly charged by the charging means. A uniformly charged image carrier is irradiated with exposure modulated on the basis of image data to form an electrostatic latent image, and toner is supplied to the image carrier on which the electrostatic latent image is formed to form a toner. When an image is formed, the toner image on the image carrier is transferred to recording paper, and the residual toner on the image carrier after the toner image is transferred onto the recording paper is removed by the cleaning unit, the friction increasing unit Since the friction coefficient of the surface of the image carrier is temporarily increased at a predetermined time, the surface friction coefficient of the image carrier is reduced with a simple configuration during normal image formation, thereby extending the life of the image carrier at low cost. And the image of the discharge product is blurred. Before, the surface friction coefficient of the image carrier is temporarily increased to remove discharge products from the surface of the image carrier, avoid image blur, prevent image deterioration, and maintain a constant image quality. In addition, image blur can be avoided.

According to the image forming apparatus of the present invention, the friction coefficient on the surface of the image carrier is temporarily increased by the friction increasing means at the predetermined time when the image carrier has rotated to the predetermined rotation speed. Therefore, when the image carrier is used up to the rotation speed before the image blur occurs due to the discharge product adhered to the surface, the surface friction coefficient of the image carrier is temporarily increased and the discharge product is imaged. It is possible to prevent the image from deteriorating by removing it from the surface of the carrier to prevent the image blur, and to avoid the image blur while keeping the image quality constant.

According to the image forming apparatus of the third aspect of the invention, the friction coefficient of the surface of the image carrier is temporarily increased by the friction increasing means at a predetermined time when a predetermined time has elapsed. When the carrier is used until the time before image blurring occurs due to the discharge products adhered to the surface, the surface friction coefficient of the image carrier is temporarily increased to remove the discharge products from the image carrier surface. Thus, it is possible to prevent image blur by avoiding image blur, and to avoid image blur while maintaining a constant image quality.

According to the image forming apparatus of the present invention, when the power of the image forming apparatus is turned on as a predetermined time, the friction increasing means temporarily increases the friction coefficient of the surface of the image carrier. Therefore, every time the power of the image forming apparatus is turned on, the surface friction coefficient of the image carrier is temporarily increased to remove discharge products from the surface of the image carrier, thereby avoiding image blur and deteriorating the image. Can be prevented, and image blur can be avoided while keeping the image quality constant.

According to the image forming apparatus of the fifth aspect, the friction coefficient of the surface of the image carrier is increased by the friction increasing means when the image formation is not performed or when the image formation is temporarily interrupted. Since it is temporarily raised, image formation is performed in a state where the surface friction coefficient of the image carrier is temporarily increased, and it is possible to prevent formation of an image with poor image quality. In addition, image blur can be avoided while always keeping the image quality constant.

According to the image forming apparatus of the present invention, since polytetrafluoroethylene is used as the lubricant, the surface friction coefficient of the image carrier is temporarily increased and the friction is reduced. By performing the transfer quickly, the amount of wear of the image carrier can be further reduced, the life of the image carrier can be further extended, and the image quality can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of an image forming apparatus to which an embodiment of the image forming apparatus of the present invention is applied.

FIG. 2 is a schematic configuration diagram of a main part of the image forming apparatus of FIG. 1 in a case where a lubricant application unit that applies a lubricant directly to the surface of a photoconductor is used to supply the lubricant to the photoconductor.

FIG. 3 is a schematic configuration diagram of a main part of the image forming apparatus of FIG. 1 in a case where a lubricant application unit that supplies a lubricant to a photoconductor via a cleaning brush of a cleaning unit is applied;

FIG. 4 is a diagram showing a relationship between a friction coefficient of a photoconductor surface and a wear amount of the photoconductor.

FIG. 5 is a diagram showing a state in which the coefficient of friction of the surface of a photoreceptor is measured by the Euler belt method.

FIG. 6 is a diagram showing the relationship between the number of prints and the coefficient of friction of the photoconductor surface.

FIG. 7 is a flowchart showing a discharge product removal process by the image forming apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoreceptor 3 Charging part 4 Developing part 5 Transfer part 6 Cleaning part 7 Static elimination part 8 Recording paper 9 Laser beam 10 Developing unit 11 Developing roller 12 Supply roller 13 Cleaning case 14 Cleaning brush 15 Cleaning blade 16 Waste toner conveyance Screw 20 Lubricant application part 21 Lubricant 22 holder 23 Elastic member 30 Lubricant application part 31 Lubricant 32 holder

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuto Yokokawa 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Masayuki Ueda 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh F term (reference) 2H027 DA41 DE07 ED24 EE06 HB06 HB14 ZA07 2H034 AA07 4H104 CD02A PA04

Claims (6)

[Claims] An image bearing member, to which a lubricant is supplied by a lubricant supplying unit and whose friction is reduced, is uniformly charged by a charging unit, and the uniformly charged image bearing member converts image data into image data. Forming an electrostatic latent image by irradiating a modulated exposure based on the
Toner is supplied to the image carrier on which the electrostatic latent image is formed to form a toner image, the toner image on the image carrier is transferred to recording paper, and the toner image is transferred to the recording paper. In the image forming apparatus for removing residual toner on the image carrier after the cleaning by a cleaning device, a friction increasing device for temporarily increasing a friction coefficient of the surface of the image carrier at a predetermined time is provided. Image forming device. 2. The image forming apparatus according to claim 1, wherein the friction increasing means temporarily increases the friction coefficient of the surface of the image carrier by setting the rotation of the image carrier to a predetermined number of revolutions as the predetermined time. The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein, when the predetermined time has elapsed, the predetermined time is used as the predetermined time, and the friction increasing means temporarily increases the friction coefficient of the surface of the image carrier. Image forming apparatus. 4. The image forming apparatus according to claim 1, wherein when the power of the image forming apparatus is turned on, the predetermined time corresponds to the predetermined time, and the friction increasing means temporarily increases the friction coefficient of the surface of the image carrier. The image forming apparatus according to claim 1. 5. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to temporarily reduce the coefficient of friction of the surface of the image carrier by the friction increasing unit when the image forming is not performed or the image forming is temporarily stopped. The image forming apparatus according to claim 1, wherein the height of the image forming apparatus is increased. 6. An image forming apparatus according to claim 1, wherein said lubricant is polytetrafluoroethylene.