JP4451246B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a process cartridge used for image formation by an electrostatic copying process such as a copying machine, a printer, and a facsimile machine, and also relates to an image forming apparatus used for the process cartridge.

The image forming apparatus develops a latent image formed on the image carrier with toner, thereby forming a toner image on the image carrier (hereinafter referred to as a photoreceptor), and this toner image is applied to the transfer material. Transfer by electrostatic force. The toner is mainly composed of a resin having thermoplasticity, and has a property that it easily adheres to the surface of the photoreceptor due to heat or pressure. For this reason, if the adhesive force is strong, it cannot be removed by the cleaning device and remains on the image carrier, which may cause a situation in which the subsequent image is deteriorated. In addition, when the toner is transferred to the transfer material, if the adhesive force is strong, the ratio of the toner transferred to the transfer material decreases, the image density decreases, and the amount of toner collected by the cleaning device increases. The problem that it happens.
In order to solve such problems, a method of applying a lubricant to the surface of the photoreceptor has been proposed so far in order to make the toner hardly adhere to the surface of the photoreceptor.

  On the other hand, many studies have been made on the charging of the image carrier. In particular, various studies have been made so far on how to reduce the ozone generated when charging a photoconductor using a corona discharge phenomenon. It has been found that the amount of generated ozone can be greatly reduced by contacting or bringing into contact with water. In particular, the proximity charging method in which a minute gap is formed has an advantage that contamination by toner on the image carrier is small.

By the way, in recent years, along with the colorization and miniaturization of the image forming apparatus, further miniaturization of the image forming apparatus per color is required. In addition to this, regarding the lubricant coating apparatus and the charging apparatus, Similarly, miniaturization is required.
In order to meet such demands, in recent years, a method of applying a lubricant using a contact charging device has been proposed.
As such a contact charging device having a lubricant application means, for example, in the invention described in Patent Document 1, the charging device contacts the image carrier and is applied with a charging voltage to make the image carrier uniform. A contact charging member that is electrically charged, an elastic member that supports the charging member, a lubricant supply member that supplies a lubricant to the charging member, a cleaning member that cleans the charging member, and a case in which these members are housed. And the lubricant is supplied to the charging member and cleaned by the action of the elastic member. Specifically, the lubricant supply member and the charging member are charged by the expansion and contraction of the elastic member supporting the charging member. The lubricant is applied to the charging member in contact with the member, and at the same time, the charging member is cleaned by the expansion and contraction of the elastic member. It has become.

  In the invention described in Patent Document 2, a charging roller is brought into contact with a rotationally driven photosensitive drum, the charging roller is driven to rotate in a direction opposite to the photosensitive drum, and the charging roller generates a bus. A cleaning member is brought into contact along the surface. The cleaning member is composed of a support member, an oil-containing layer such as a malt plain, and an oil coating layer such as a fine fiber layer. By this cleaning member, the surface of the charging roller 2 and further the surface of the photosensitive drum 1 are lubricated. Is applied to form a release layer on these surfaces. With this release layer, the friction acting between each member such as a charging roller, a photosensitive drum, a transfer roller, and a cleaning blade can be reduced to reduce wear.

Further, in the invention described in Patent Document 3, the lubricant application mechanism includes a lubricant, an elastic member that presses the lubricant, and a constant amount of lubrication on the peripheral surface as the lubricant is elastically pressed and rotated. And a rotating brush roller that rotates in contact with the rotating roller and the charging roller and transfers the lubricant on the rotating roller onto the charging roller. While rotating with respect to the body, the photosensitive member is uniformly charged and has a function of transferring the lubricant applied by the rotating brush onto the photosensitive member. Since the toner is collected in the cleaning unit and the lubricant is transferred to the cleaned photoconductor, a certain amount of lubricant can be transferred onto the photoconductor without being disturbed by the toner. Therefore, the lubricant can be prevented from being mixed into the developing portion.
As described above, the space can be saved by adopting a configuration in which the lubricant is applied by the contact charging device.

JP 2000-066487 A JP 7-199600 A Japanese Patent Laid-Open No. 10-142897

However, in the inventions described in Patent Documents 1 to 3, since the charging device is a contact type, the charging and lubricant application operations cannot be performed separately, and the charging device is always capable of carrying an image during image formation. It is in contact with the body. In such a state, the coating surface (charging member surface) is contaminated, and a mixture of a lubricant and a residue such as toner is applied to the surface of the image carrier. Will deteriorate. The term “deterioration” as used herein refers to a state in which the lubricant adheres to the toner constituting the developer and the surface of the carrier and impairs the original triboelectric charge characteristics. This refers to the occurrence of a problem that the charge amount of the battery decreases.
Furthermore, when the image bearing member cleaning device is not provided and the transfer residual toner is collected by the developing device, the above phenomenon occurs more drastically.
Accordingly, in the present invention, in view of the above circumstances, the application of the lubricant by the charging device realizes reduction of ozone generation, space saving, and reduction of adhesion of the image carrier to the toner, and resistance to the image carrier. It is an object of the present invention to provide an image forming apparatus capable of realizing a contamination property (a property of being hardly contaminated by a substance).

In order to solve the above problems, the present invention has the following features.
1. An image forming apparatus of the present invention is an image forming apparatus that visualizes an electrostatic latent image formed on an image carrier with toner, and includes at least a latent image carrier, a charging device, a developing device, and / or a cleaning unit. in the image forming apparatus capable of including detachable process cartridge obtained by integrating the door, said process cartridge includes a charging member included in the charging apparatus has a means for supplying a lubricant, the charging member includes an image carrier It has a mechanism capable of coming into contact with and separated from the body, retracts during charging, and contacts the image carrier for a certain period during non-charging to apply the lubricant.
2. The image forming apparatus according to the present invention includes: In the invention described in (1), the lubricant application operation is performed when the surface of the image carrier that has passed through the charging device is not used for image formation.
3. The image forming apparatus according to the present invention includes: Or 2. In the invention described in (1), the amount of lubricant on the image carrier is detected or predicted, and when the amount is small, the lubricant application operation is started.
4). In addition, the image forming apparatus of the present invention includes: In the invention described in (1), the amount of lubricant on the image carrier is predicted based on the cumulative value of the image area formed on the image carrier.
5). The image forming apparatus according to the present invention includes: Or 4. In the invention described in any one of the above, the lubricant amount prediction operation or the lubricant application operation is performed in the region where the image is first formed from the start of the operation of the image carrier during the image formation operation. The time zone until the position of the apparatus is reached is the time zone T1, and the time zone until the image carrier stops after the last image-formed region passes the position of the lubricant application device at the end of image formation. When T2 is set, it is performed in the time zone T1 or T2.
6). The image forming apparatus according to the present invention includes: Or 5. In the invention of any one of the toner remaining on the image bearing member after the transfer device passes, you and recovering the developing device.

7). The image forming apparatus according to the present invention includes: Or 6. In any one of the inventions, the lubricant is zinc stearate.
8). The image forming apparatus according to the present invention includes: Or 7. In the invention described in any one of the above, a spacer member is provided so as to face the longitudinal end portion of the charging member and the end portion of the image carrier, and a gap between the charging member and the image carrier is charged during charging. When the lubricant is applied, the image bearing member or the charging member is shifted in the longitudinal direction of the charging member, removed from the spacer member, and brought into contact with both.

  As described above, according to the means for solving the above, in the present invention, space saving can be realized, the adhesion between the image carrier and the toner is reduced, and the image carrier is resistant to contamination (substance It is possible to provide a process cartridge and an image forming apparatus having a property of being hardly contaminated.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view showing a structure around a characteristic portion of an image forming apparatus according to the present invention.
Around the image carrier 1, a charging device 21, a writing device 22, a developing device 2, and a transfer device 18 are arranged. In the image forming apparatus of the present invention, the charging device 2 uses a non-contact charging roller 21. Thus, the roller is not easily contaminated and the generation of ozone is suppressed. The applied voltage may be only DC or AC may be superimposed on it. As for development, a two-component developing device is applied in this embodiment, but the present invention can also be applied to a one-component developing device, and can be selected for contact and non-contact. As for the transfer device 18, the transfer belt 10 is applied in this embodiment, but this may be a roller transfer or a corona transfer, or a direct transfer to a transfer material or a transfer to an intermediate transfer member. Also good.

A mechanism for supplying the lubricant 14 to the charging roller 21 according to the present invention will be described with reference to FIG.
The charging roller 21 is made of a conductive material, and is made of metal, conductive plastic, conductive rubber, or a composite thereof, and is attached to the image carrier 1 so as to be able to contact and separate and to be rotatable.
Furthermore, although the lubricant application roller 15 is in contact with the charging roller 21, the lubricant application roller 15 has a function of rubbing the lubricant 14 and applying it to the charging roller 21, so that an appropriate surface roughness is obtained. Flexibility is required to maintain the contact pressure uniformity. For this reason, the roller body is made of silicone rubber, urethane rubber, or other synthetic rubber, and a relatively hard resin coat such as polyamide, polyethylene, PET, fluorine-containing resin, or the like is used on the surface. A high one is obtained. The thing used as a roller may be foamed rubber or a roller-like brush. However, since these materials have low surface smoothness, lubricant consumption tends to increase. The lubricant application roller 15 is rotationally driven by a rotational drive device (not shown). The rotation shaft of the lubricant application roller 15 is rotatably fixed to the main body, and is preferably stopped in synchronization with the release of the charging roller 21. In this embodiment, the rotation direction at the time of rotation is the same direction as the charging roller 21 at the contact portion.

In the present invention, a block of zinc stearate is used as the lubricant 14. This zinc stearate is preferable for use as a lubricant because it has a high lubricating effect, is easily shaped, and is easily available. In addition, metal soaps, waxes, and fluorine-containing resins also show the same effect.
The lubricant 14 is made into a block shape and pressed against the application roller. As a pressing method, there are methods such as attaching a weight, utilizing gravity, applying pressure by applying a spring, and controlling a pressing force and pressurizing timing with a solenoid or the like.
The lubricant leveling blade 16 blocks excess lubricant 14 and evenly distributes the lubricant 14 applied to the charging roller 21 onto the charging roller 21, and firmly adheres it to the extra portion. It is a member for avoiding. From the standpoint of uniformity of contact and wear resistance, a blade of urethane rubber or other synthetic rubber is preferable, but a resin blade such as PET or polyamide is also effective.
The lubricant 14 is supplied to the charging roller 21 by the mechanism as described above.

FIG. 2 is a conceptual diagram of contact and separation of the charging roller 21 according to the present invention. The charging roller 21 is constantly applied with a force toward the image carrier 1 by a pressure device (not shown). This force includes the case of only the gravity of the charging roller 21 itself. At the time of charging, as shown in FIG. 2A, the charging member spacer 31 formed by winding a thin resin tape around the longitudinal end portion of the charging roller 21 and the end portion of the image carrier 1 (charging member spacer 31). An appropriate gap can be maintained between the charging roller 21 and the image carrier 1 by the effect of the image carrier spacer 32 formed in the same manner at the end opposite to the above. A suitable gap for charging is 5 to 100 μm.
On the other hand, when the charging roller 21 and the image carrier 1 are in contact with each other, as shown in FIG. 2 (b), the charging roller 21 or the image carrier 1 is shifted in the longitudinal direction by a mechanism (not shown). Can be removed from the above-mentioned spacer, and both members can be brought into contact with each other. By this method, it is possible to perform a minute gap formation and contact operation with high accuracy without using a complicated mechanism.
Note that when the gap is made again, the charging roller 21 is shifted in the opposite direction. At this time, the charging roller 21 rides on the image carrier spacer 32. It is preferable that the end of the roller 21 and the end of the image carrier 1 are chamfered so that they can be easily climbed.

In the present invention, as described above, since the charging roller 21 has a mechanism capable of coming into contact with and separating from the image carrier 1, the charging roller 21 supplied with the lubricant 14 is charged with the image carrier 1. The charging roller 21 comes into contact with the image carrier 1 and can supply the lubricant 14 onto the image carrier 1 when it is uncharged. Thereby, since the lubricant 14 is supplied to the surface of the image carrier 1, the toner cleaning property and the transfer property are improved, and the low adhesion force of the toner on the surface of the image carrier 1 is realized.
The lubricant application operation is more preferably performed at a timing when the surface of the image carrier 1 that has passed through the charging device is not used for image formation.
By adopting such a configuration, even if the charging roller 21 has two functions of an original charging function and a lubricant application function, the lubrication supplied by performing both functions in a time-sharing manner. The agent 14 can be prevented from being mixed with the residue on the image carrier 1, and a series of image forming operations can be performed without causing the problem of charging roller contamination.

Note that the image forming apparatus of the present invention does not include a cleaning device, and is configured to collect the toner remaining on the image carrier 1 after passing through the transfer device 18 in the developing device 2.
As a result, the space can be saved. By adopting the above-described configuration, the charging roller 21 is prevented from being contaminated, and the residue on the image carrier 1 is separated from the lubricant 14. This can be realized because the situation of mixing is avoided.

In the present invention, the lubricant amount on the image carrier 1 is detected or predicted from the cumulative value of the area of the image formed on the image carrier 1, and the lubricant amount based on the detection or prediction is determined. When the amount is low, the lubricant application operation is started. As a result, the amount of the lubricant 14 used can be saved, and further, a problem due to an excessive amount of the lubricant applied, for example, the surface friction coefficient becomes small, so that the toner hardly adheres and the development amount decreases. It is possible to avoid such a phenomenon.
Here, the detection or prediction operation of the lubricant amount performed from the cumulative value of the area of the image formed on the image carrier 1 will be described. When toner is present on the image carrier 1, the surface area of the toner is present. Therefore, a large amount of the lubricant comes in contact with the toner from the surface of the image carrier, and the lubricant is consumed from the image carrier 1.
That is, since there is a correlation between the area of the toner image formed on the image carrier 1 and the amount of lubricant consumed from the image carrier 1, this fact is used to detect the area of the toner image. By doing so, it was decided to predict the remaining amount of lubricant.
Note that the detection or prediction operation of the lubricant amount is not limited to this method, and may be performed by another method.

During the image forming operation, the time zone from when the image carrier 1 starts to move until the region where the image is first formed reaches the position of the lubricant application device is the time zone T1, and the last time when the image formation is completed. When the time zone from when the region where the image is formed passes through the position of the lubricant application device to when the image carrier stops is time zone T2, the above-mentioned lubricant amount prediction operation or lubricant application operation Is preferably performed preferentially during the time period T1 or T2.
This time zone T1 or T2 is a time zone necessary for the image forming apparatus 1 to perform initialization, charge removal processing, or the like in the image forming apparatus. Therefore, it is necessary to provide a dedicated rotation of the image carrier 1 for the lubricant amount predicting operation or the lubricant applying operation by performing the lubricant amount predicting operation or the lubricant applying operation in these time zones. And the purpose can be achieved more efficiently.

In FIG. 1, the image carrier 1 and the developing device 2, the charging roller 21, the lubricant 14, the lubricant application roller 15, and the lubricant leveling blade 16 are integrally configured as a process cartridge that can be attached to and detached from the apparatus main body. The image forming apparatus main body can also be provided.
FIG. 3 is a schematic diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. By providing the image forming apparatus main body 50 with the process cartridge in a detachable manner, if a failure caused by a part or apparatus included in the process cartridge occurs, the process cartridge is replaced, so that Can be repaired, so that the apparatus can be restored at an early stage. In this respect, it is advantageous for maintenance, and the effect that the service time can be shortened is obtained.

1 is a schematic view showing a structure around a characteristic part of an image forming apparatus of the present invention. It is a conceptual diagram of the contact and separation of the charging roller 21 according to the present invention. 1 is a schematic diagram illustrating a configuration of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image carrier 2 Developing apparatus 3 Developing roller 4 Developing sleeve 5 Magnet 6 Doctor blade 7 Developer conveying screw A
8 Developer transport screw B
9 Developer stencil plate 10 Transfer belt 11 Transfer belt stretching roller 12 Transfer belt drive roller 14 Lubricant 15 Lubricant application roller 16 Lubricant leveling blade 18 Transfer device 21 Charging roller 22 Writing device 31 Charging member spacer 32 Image carrier Spacer 50 Image forming apparatus

Claims (8)

An image forming apparatus for visualizing an electrostatic latent image formed on an image carrier with toner, and a process cartridge in which at least a latent image carrier, a charging device, a developing device and / or a cleaning unit are integrated. In an image forming apparatus that is detachably provided,
The process cartridge is
A charging member included in the charging apparatus has a means for supplying a lubricant,
The charging member has a mechanism capable of coming into contact with and separating from the image carrier, retracts when charged, and contacts the image carrier for a certain period of time when not charged to apply a lubricant. An image forming apparatus . The image forming apparatus according to claim 1.
The operation of applying the lubricant is as follows:
An image forming apparatus, which is performed when an image carrier surface that has passed through a charging device is not used for image formation . The image forming apparatus according to claim 1, wherein
The process cartridge is
An image forming apparatus , comprising: detecting or predicting an amount of lubricant on an image carrier, and starting a lubricant application operation when the amount is small. The image forming apparatus according to claim 3.
An image forming apparatus , wherein the amount of lubricant on the image carrier is predicted based on a cumulative value of an image area formed on the image carrier. The image forming apparatus according to any one of claims 1 to 4,
The predictive operation of the lubricant amount or the operation of applying the lubricant is as follows:
During the image forming operation, the time zone from the start of the operation of the image carrier until the region where the first image is formed reaches the position of the lubricant application device is a time zone T1, and the last image is formed at the end of the image forming operation. When the time zone from when the region passes the position of the lubricant application device to when the image carrier stops is T2,
An image forming apparatus, which is performed during a time period T1 or T2. The image forming apparatus according to any one of claims 1 to 5,
The process cartridge is
An image forming apparatus , wherein a toner remaining on an image carrier after passing through a transfer device is collected by a developing device . The image forming apparatus according to any one of claims 1 to 6,
The image forming apparatus , wherein the lubricant is zinc stearate. The image forming apparatus according to any one of claims 1 to 7,
The process cartridge is
A spacer member is provided opposite to the longitudinal end of the charging member and the end of the image carrier,
During charging, a gap between the charging member and the image carrier is formed by the spacer member,
An image forming apparatus comprising: a mechanism for shifting the image carrier or the charging member in the longitudinal direction of the charging member and removing the spacer from the spacer member when the lubricant is applied.

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