JP5617459B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus for applying a lubricant to a photosensitive drum.

Conventionally, an image forming apparatus has an advantage that a mechanism for applying a lubricant by pressing a solid lubricant against a brush with a spring can be simply configured.
However, as the travel distance of the photosensitive drum increases, the spring pressing force becomes weak and the lubricant cannot be applied sufficiently, and the lubricant application state on the photosensitive drum depends on the image conditions printed by the user. There was a drawback of changing.
In conventional image forming apparatuses, a technique of applying a lubricant is often used in a cleaning process using a rubber blade or the like around a photosensitive drum or a transfer belt. In this technique, it is required to stably supply the lubricant application for a long period of time. If the lubricant is not applied sufficiently, cleaning failure may occur, other problems such as filming may occur on the photosensitive drum, and the photosensitive drum may deteriorate due to charging hazard. There was a problem of speeding up.
Accordingly, it is an important issue to stably apply the lubricant in order to extend the life of the photosensitive unit.

Conventionally, Patent Documents 1 to 3 have been reported for stably applying a lubricant.
In Patent Document 1 and Patent Document 2, a conventional solid lubricant is scraped off with an application brush and applied directly to the photosensitive drum, or the lubricant scraped off by applying a brush to a flicker is ejected and applied to the photosensitive drum. The method is described.
Patent Document 3 describes a method of applying a powder lubricant to a photosensitive drum using the force of an electric field.
As in Patent Document 1 and Patent Document 2, the method of scraping and applying a solid lubricant with a brush has a problem that the application state is easily influenced by the image printed by the user. Specifically, solid lubricants are easy to scrape if there is toner input, and conversely difficult to scrape if there is no toner input, which inevitably causes uneven coating in the longitudinal direction of the photosensitive drum. .
In Patent Document 3, the powder lubricant is applied by using the force of an electric field, but an image defect due to the use of the electric field is a problem. Since the lubricant is applied before the charging process, there is a problem that the residual potential of the photosensitive drum due to the application may appear in the image.
Further, in Patent Document 4, in order to replace the solid lubricant, it is necessary to take out the unit from the apparatus and disassemble the unit, and it is necessary for a service person to deal with it. There was a problem.

Furthermore, recently, there is a need to use electrophotographic technology in the printing industry, and the types and number of images output by users are diversifying, and more stable lubricant application technology is required.
An object of the present invention is to provide an image forming apparatus that can efficiently apply a lubricant to a photosensitive drum and extend the life of the photosensitive unit.

In order to solve the above problems, a first aspect of the present invention, an image bearing member for bearing a latent image, a charging means for applying a uniformly charged surface of the image bearing member, the surface of the charged image bearing member An exposure unit for exposing the image to the latent image formed on the surface of the image carrier, a developing unit for supplying toner to the latent image formed on the surface of the image carrier, and a visible image on the surface of the image carrier. Transfer means for transferring a visual image to a transfer medium, cleaning means for cleaning the surface of the image carrier after the transfer, and lubricant application means for applying a lubricant to the surface of the image carrier after the cleaning. In the image forming apparatus, the lubricant application unit injects powder lubricant from a plurality of heads arranged on a line with respect to the longitudinal direction of the image carrier, and the head is responsive to an applied voltage. A piezo element that deforms, Deforming the Ezo element, characterized in that injecting the lubricant.

  According to the present invention, the lubricant can be efficiently applied to the photosensitive drum, and the lifetime of the photosensitive unit can be extended.

1 is an overall view of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view of an image forming unit used in an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing that a predetermined element is provided in a lubricant application head used in an image forming apparatus according to an embodiment of the present invention, and a schematic diagram showing a state when the lubricant application head is deformed or bent (b). ) Is a schematic diagram (c) showing a state in which the lubricant application heads are arranged on a line with respect to the longitudinal direction of the photosensitive drum.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings. In the following embodiments, a copier capable of forming a full-color image using a tandem method will be described as the image forming apparatus. However, the image forming apparatus according to the present invention is not limited to the illustrated one, and may be a printer. It can be applied to various apparatuses such as a facsimile apparatus and a composite apparatus.

  The present invention is characterized in that a powder lubricant is first applied to the lubricant by applying the head technology used in the ink jet technology. The primary advantage is that the amount of lubricant applied can be adjusted based on image information printed by the user.

With reference to FIGS. 1 and 2, the basic configuration and operation of a copying machine as an image forming apparatus will be described.
FIG. 1 is a cross-sectional view showing the overall configuration of the copying machine, and FIG. 2 is a cross-sectional view showing the configuration around the image carrier.
The copying machine shown in the figure has a configuration in which a paper feeding unit having a paper feeding tray 20 for storing paper as a recording material is provided at the lower part of the apparatus main body 100, and an image forming unit 32 is arranged above the paper feeding unit. .
The image forming unit 32 includes four image forming units as a plurality of image forming units including image carriers 1Y, 1M, 1C, and 1K (hereinafter referred to as the image carrier 1 unless it is particularly necessary to specify a color). An intermediate transfer belt 10 as an intermediate transfer member composed of a unit and a flexible endless belt wound around a plurality of rollers 11, 12, and 13, and latent image formation for forming a latent image on each image carrier An optical writing unit 4 that is a device, a fixing device 23 that fixes a toner image on a sheet, and the like are provided. A transport path for transporting paper is formed between the paper feed cassette 20 and the fixing device 23. In FIG. 1, 21 is a calling roller, and 22 is a registration roller.

  The space between the roller 11 and the roller 12 of the intermediate transfer belt 10 corresponds to the lower belt running side of this belt. The intermediate transfer belt 10 is provided with a secondary transfer roller 16 serving as a secondary transfer device facing a roller 13 at a portion facing the roller 13, and cleaning the belt surface at a portion facing the roller 11. A device 15 is provided.

  The image forming unit 30 is disposed below the intermediate transfer belt 10 by being disposed so as to face the lower running side. Each image forming unit includes an image carrier 1 in contact with the intermediate transfer belt 10. Around each image carrier 1, a charging roller 7, a developing unit 9, a cleaning device 17, and a lubricant application device 18 are arranged. A transfer roller 14 as a transfer device that performs primary transfer is provided inside the intermediate transfer belt 10 at a position where each image carrier 1 is in contact with the intermediate transfer belt 10.

  In the present embodiment, the image forming units basically have the same structure, and only the structure of one image forming unit is shown. The difference in each image forming unit is that the color of toner as a developer stored in each developing device 9 is different.

  The optical writing unit 4 irradiates the surface of each image carrier 1 with light-modulated laser light L to form a latent image for each color on the surface of the image carrier. In this embodiment, the image forming unit 32 is disposed below.

  Further, as shown in FIG. 1, toner bottles 31Y, 31M, 31C, and 31K (hereinafter referred to as toner bottle 31 unless otherwise specified) are usually provided in the upper portion of the apparatus main body 100. Toner is replenished by replacing only the toner bottle 31, and a lubricant replenishing bottle 30 is arranged so that each photoreceptor unit can be replenished. The process is performed only when the process cartridge such as the image carrier 1 or the charging roller 7 is replaced. Replace the entire cartridge.

  In FIG. 1, the toner bottle 31 is arranged on the upper side of the machine for each color, and the toner is transported to the process cartridge for each color on the lower side to replenish the toner. With such a configuration, it is usually only necessary to replace the toner bottle, so that the cost burden on the user can be reduced. Further, since the number of times of opening / closing and taking in / out of other parts of the apparatus is reduced, it is possible to prevent toner scattering at the shutter portion and the like, thereby improving maintenance.

Next, an image forming operation will be described.
When the image forming operation starts, the image carrier 1 of each image forming unit is rotated clockwise by a driving device (not shown), and the surface of each image carrier 1 is uniformly charged to a predetermined polarity by the charging roller 7. .
The surface of each charged image carrier 1 is irradiated with laser light L from the optical writing unit 4 to form an electrostatic latent image on each surface. At this time, for example, the image information read on each image carrier 1 by an arithmetic unit using an image read by the scanner 40 is a desired full-color image of yellow (Y), cyan (C), magenta (M) and black (K ) Color information separated into color information. The electrostatic latent image formed in this way is visualized as a toner image by the toner stored in each developing unit 9 when passing between each image carrier 1 and developing unit 9.

  One of the plurality of rollers 11, 12, and 13 around which the intermediate transfer belt 10 is wound is driven to rotate counterclockwise by a driving device (not shown), thereby driving the intermediate transfer belt 10 to travel, The driven roller is rotated. The toner image of each color formed by each image forming unit is sequentially superimposed and transferred onto the intermediate transfer belt 10 that travels in this way by a primary transfer roller (not shown), and the surface of the intermediate transfer belt 10 is full color. A toner image is carried.

  Residual toner adhering to the surface of each image carrier 1 after the transfer of the toner image is removed from the surface of each image carrier 1 by the cleaning device 17, and the surface of the image carrier 1 is neutralized by a static eliminator (not shown). The surface potential is initialized to prepare for the next image formation. As shown in FIG. 2, the cleaning device comprises a blade 17a such as urethane rubber, scrapes the toner from each image carrier, rotates the collection coil 17b, conveys the toner, and discards the waste toner bottle. Recover.

  On the other hand, the paper fed from the paper feed tray 20 is sent to the transport path, and the roller 13 and the secondary transfer roller 16 are fed by the registration roller pair 22 disposed on the paper feed side with respect to the secondary transfer roller 16. Feed to the opposite part. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt 10 is applied to the secondary transfer roller 16, thereby collectively transferring the toner images on the surface of the intermediate transfer belt 10 onto the sheet. Transcript. The sheet on which the toner image has been transferred is conveyed to the fixing device 23, and heat and pressure are applied when passing through the fixing device 23 to melt and fix the toner image. Then, the sheet on which the toner image is fixed, that is, the printed sheet, is conveyed to a discharge roller 24 positioned at the end of the conveyance path provided near the upper part of the apparatus main body 100, and a stacking unit configured on the upper part of the apparatus main body 100. To discharge. The toner remaining on the intermediate transfer belt 10 after the toner image is transferred onto the sheet is removed from the cleaning device 15.

  The copying machine configured in this manner is provided with four image forming units opposed to the intermediate transfer belt 10, and sequentially transfers the toner images of the respective colors onto the intermediate transfer belt 10, so that one image forming unit is provided. The image forming time can be greatly reduced as compared with a type having a four-color developing device and transferring the toner image on the intermediate transfer belt in a superimposed manner and then transferring it onto the paper. Further, since the stacking unit is formed in the upper part of the apparatus main body 100, the stacking unit does not jump out from the apparatus main body 100 to the surroundings, and the installation area and the occupied area are reduced.

  The above description is an image forming operation when a full color image is formed on a sheet. However, a single color image can be formed using any one of the image forming units of the image forming unit 32, or two colors. Alternatively, it is possible to form a three-color image. When monochrome printing is performed using the printer of the present embodiment, an electrostatic latent image is formed only on the photosensitive drum 1K of the black image forming unit, developed by the unit, transferred to the paper, Fixing may be performed by the fixing device 23.

  As shown in FIG. 2, the image forming unit is a so-called process cartridge, and the image carrier 1, the developing unit 9, the cleaning device 17, the lubricant applying device 18, and the charging roller 7 are integrally configured. It can also be easily removed from the main machine.

Next, the lubricant application device will be described.
As shown in FIG. 2, the lubricant application device 18 is located downstream of the cleaning blade 17a (in the rotational direction of the photosensitive drum 1), and is disposed at a position for applying the lubricant onto the cleaned photosensitive drum. It is. In this embodiment, the blade is disposed as a lubricant break-in member after application of the lubricant, but the present invention is not limited to this, and a configuration in which the blade is not attached or a configuration in which the photosensitive drum is fitted with the application brush may be used. .
As shown in FIG. 3A, the lubricant application device 18 is configured such that the lubricant is supplied from the lubricant replenishment bottle 30 through the tube 18a to the respective lubricant application heads 18c by the pressure of the pump 18b. Yes.

  As the lubricant supply head 18c, any one of a piezo method using a piezo element using voltage and a thermal method using a bimetal element using heat may be used.

  The piezo method utilizes the property of the piezo element 18d that deforms when a voltage is applied. The piezo element 18d is attached to a fine tube 18e packed with a powder lubricant, and a voltage is applied to the piezo element 18d. FIG. As shown in FIG. 5, the surface of the piezo element 18d is deformed, and the lubricant in the head is pushed out from the opening 18f provided at the end of the micro tube 18e to fly.

  The piezo element is configured to form two electrodes on both sides in the thickness direction of the piezoelectric material, and is an element that expands and contracts in the direction corresponding to the polarity of the voltage applied to the two electrodes. It is characterized by high time response.

The thermal method is slightly different from the thermal method used in, for example, an ink jet printer, and a bimetal element 18d made of a metal having a different coefficient of thermal expansion is arranged in the head, and an electric current is applied to the bimetal element 18d to overheat and warm the metal. As shown in FIG. 3 (b), the lubricant in the head is pushed out from the opening 18f provided at the end of the fine tube 18e by bending due to the difference in thermal expansion coefficient.
For example, in an inkjet printer, the ink itself is heated to generate air bubbles and eject the ink. In this method, the bimetal element 18d is heated to deflect the bimetal element 18d and generate pressure in the head. A powder lubricant is allowed to fly from an opening 18f provided at the end of the microtube 18e.

  The bimetal element 18d is composed of two metals having different expansion coefficients formed by adding a metal such as manganese, chromium and copper to an alloy of iron and nickel, and the bimetal element 18d has an overload current. When the gas flows for a predetermined time, it is heated to warm the two metals, so that bending occurs due to the difference in thermal expansion coefficient.

  As shown in FIG. 3C, the head 18c has an opening 18f facing the longitudinal direction of the photosensitive drum as the image carrier 1, and a plurality of heads 18c are arranged in a line on the line. Various arrangement configurations such as an arrangement arranged in a row or an arrangement arranged alternately in two rows on a line may be used. Although the present invention is illustrated as an example of a configuration in which two lines are alternately arranged on a line, the present invention is not limited to such a head configuration.

  The amount of lubricant to be supplied is determined by image information printed by the user. When the copying machine main body receives the print job information, the main control unit calculates the image printing rate in the longitudinal direction of the photosensitive drum using the main body memory. Based on the result of the calculation, the lubricant application amount is increased in the portion where image printing is large in the longitudinal direction of the photosensitive drum, and the lubricant supply amount is decreased in the portion where image printing is small. To control. In this way, by controlling the amount of lubricant supplied, without causing problems such as contamination of the charging roller due to excessive lubricant, insufficient cleaning due to lack of lubricant, filming, etc. It is possible to provide a stable image for a long period of time.

  In the image forming apparatus according to the present embodiment, an image carrier that carries a latent image, a charging unit that uniformly charges the surface of the image carrier, and the surface of the charged image carrier is exposed based on image data. , An exposure means for writing a latent image, a developing means for supplying toner to the latent image formed on the surface of the image carrier and making it visible, and a transfer means for transferring the visible image on the surface of the image carrier to a transfer medium And an image forming apparatus comprising: a cleaning unit that cleans the surface of the image carrier after the transfer; and a lubricant application unit that applies a lubricant to the cleaned surface of the image carrier. Powder lubricant is injected from a plurality of heads arranged on the line with respect to the longitudinal direction of the carrier, so that the head for applying the lubricant can be arranged on the line with respect to the image carrier. , Where the lubricant needs to be applied It is possible to supply necessary amount. As a result, the photosensitive roller unit is stable without causing problems such as contamination of the charging roller due to excessive supply of the lubricant or insufficient cleaning, filming, abnormal noise of the cleaning blade due to insufficient supply of the lubricant. As a result, the lubricant can be efficiently applied to the photosensitive drum, and the life of the photosensitive unit can be extended.

  In the image forming apparatus according to the present embodiment, the head has a piezo element that deforms according to the applied voltage, and the lubricant is efficiently applied to the photosensitive drum by deforming the piezo element and injecting the lubricant. It can be applied by flying toward.

  In the image forming apparatus according to this embodiment, the head has a bimetal element that bends in response to heating, and the lubricant is efficiently directed to the photosensitive drum by injecting the lubricant by bending the bimetal element. Can be applied by flying.

  In the image forming apparatus according to the present embodiment, the amount of lubricant to be applied can be determined based on image information to be printed. Therefore, an appropriate amount of lubricant can be efficiently matched to the image information to be printed. Can be applied to the drum.

  In the image forming apparatus according to the present embodiment, the powder lubricant can be put in a predetermined replaceable container, so that maintenance by a service person is not necessary, and the user can replace the container freely by himself / herself. In addition, since the user can replace the lubricant by himself / herself, the exhaustion of the lubricant can be prevented, the maintenance work of the unit can be saved, and the life of the unit can be extended. The container may be a container such as a PET bottle.

  In the image forming apparatus according to the present embodiment, the powder lubricant is made of a fatty acid metal salt. Examples of the fatty acid metal salt include fatty acid metal salts of linear hydrocarbons such as myristic acid, palmitic acid, stearic acid, and oleic acid. Examples of the metal include lithium, magnesium, calcium, strontium, zinc, cadmium, Examples include aluminum, cerium, titanium, and iron. Among these, zinc stearate, magnesium stearate, aluminum stearate, iron stearate and the like are preferable, and zinc stearate is particularly preferable. By applying a powder lubricant to the photosensitive drum, the surface of the photosensitive drum and the transfer belt can be protected, and a stable image free from filming and poor cleaning can be provided.

  In the image forming apparatus according to the present embodiment, since the process cartridge including the image carrier and the lubricant applying unit is detachably provided in the apparatus main body, the replacement work is facilitated. In the event of a failure, the process cartridge can be quickly replaced for each color.

  The present invention can be used for a printer, a facsimile machine, a composite machine, and the like.

DESCRIPTION OF SYMBOLS 1 Image carrier 4 Optical writing unit 7 Charging roller 9 Developing unit 10 Intermediate transfer belt 11 Roller 12 Roller 13 Roller 14 Transfer roller 15 Belt cleaning device 16 Secondary transfer roller 17 Cleaning device 17a Cleaning blade 17b Recovery coil 18 Lubricant coating device 18a Tube 18b Pump 18c Lubricant application head 18d Piezo element (or bimetal element)
18e Micro tube 18f Opening 20 Feed tray 21 Calling roller 22 Registration roller 23 Fixing device 30 Lubricant replenishment bottle 31 Toner bottle 32 Image forming unit 40 Scanner

JP 2009-53535 A JP 2007-310121 A JP 2008-88771 A JP 2009-8819 A

Claims (6)

An image carrier for carrying a latent image;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the charged image carrier based on image data and writing a latent image;
Developing means for supplying a toner to the latent image formed on the surface of the image bearing member to visualize the latent image;
Transfer means for transferring a visible image on the surface of the image carrier to a transfer medium;
Cleaning means for cleaning the surface of the image carrier after the transfer;
In an image forming apparatus comprising a lubricant application unit that applies a lubricant to the surface of the image carrier after the cleaning,
The lubricant applying means injects a powder lubricant from a plurality of heads arranged in a line with respect to the longitudinal direction of the image carrier ,
The image forming apparatus , wherein the head includes a piezo element that deforms according to an applied voltage, and the lubricant is ejected by deforming the piezo element . An image carrier for carrying a latent image;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the charged image carrier based on image data and writing a latent image;
Developing means for supplying a toner to the latent image formed on the surface of the image bearing member to visualize the latent image;
Transfer means for transferring a visible image on the surface of the image carrier to a transfer medium;
Cleaning means for cleaning the surface of the image carrier after the transfer;
In an image forming apparatus comprising a lubricant application unit that applies a lubricant to the surface of the image carrier after the cleaning,
The lubricant applying means injects a powder lubricant from a plurality of heads arranged in a line with respect to the longitudinal direction of the image carrier,
The image forming apparatus , wherein the head includes a bimetal element that bends in response to heating, and the bimetal element is deflected to inject a lubricant . The image forming apparatus according to claim 1.
The amount of the lubricant to be applied is determined based on image information to be printed. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the powder lubricant enters a predetermined replaceable container. The image forming apparatus according to claims 1 to 4,
The image forming apparatus, wherein the powder lubricant comprises a fatty acid metal salt. The image forming apparatus according to claim 1.
An image forming apparatus, wherein a process cartridge including the image carrier and a lubricant application unit is detachably provided on the apparatus main body.

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