JP2005266516A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is devised to limit the quantity of lubricants to be supplied to both terminal portions of an image carrier in comparison with a central portion. <P>SOLUTION: There are provided a brush comprising a cleaning blade which is abutted on a surface of an image carrier to scrape off the residual on the surface of an image carrier after transfer of a toner image to the other, a shaft arranged in parallel with a rotation axis and a plurality of bristle portions aligning a plurality of bristles radially extending from the shaft in the extension direction of the shaft, and rotating around the shaft while setting top ends of the bristles in contact with the surface of the image carrier, and a lubricant supply member facing the portion of the shaft where the bristle portions are provided, and arranged with solid lubricants to which the top ends of the bristle portions are contacted. The shaft is adopted, in which a diameter of both terminals of the portion, where the bristle portions are provided, in the extension direction is smaller than a diameter of the center in the portion where the bristle portions are provided, in the extension direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention forms an image composed of a fixed toner image on a recording medium by forming a toner image on the surface of an image carrier and finally transferring and fixing the toner image on a predetermined recording medium. The present invention relates to a forming apparatus.

  Conventionally, in an image forming apparatus of a type in which an electrostatic latent image formed on a surface of a photoconductor rotating in a predetermined direction is developed using a developer containing toner to form a toner image on the surface of the photoconductor, intermediate transfer is performed. Some have a cleaning blade in contact with the photosensitive member for cleaning the residue remaining on the surface of the photosensitive member after the transfer of the toner image onto a belt or recording paper.

  In such an image forming apparatus, the external additive contained in the developer together with the toner remains in the residue. This external additive has a smaller particle diameter than that of the toner, and if this external additive passes an appropriate amount between the cleaning blade and the surface of the photoreceptor, a so-called slip effect is produced between them. Therefore, the frictional force between them does not increase so much. However, for example, when a toner image having a low image density is continuously formed, the amount of the external additive in the residue decreases, so that the frictional force between them increases, causing damage to the cleaning blade and photosensitivity. It is known that body wear increases.

  In view of this, it has been proposed to provide a rotating brush for supplying a lubricant to the surface of the photoconductor after the toner image is transferred, upstream of the cleaning blade in the rotation direction of the photoconductor.

  FIG. 1 is a view showing a rotating brush for supplying a lubricant.

  FIG. 1 shows a photoconductor 101, a charger 102 for applying a predetermined charge to the photoconductor 101, and the surface exposed to form an electrostatic latent image on the surface of the photoconductor 101 to which a predetermined charge is applied. An exposure device 103 for developing, a developing roll 104 for developing the electrostatic latent image formed on the surface of the photosensitive member 101 with a developer containing toner, and a toner image formed on the photosensitive member by toner development by a transfer device 105. An intermediate transfer belt 112 to be transferred, a rotating brush 116 for supplying the lubricant scraped from the solid lubricant 111 to the surface of the photoreceptor, and a blade 113b for scraping the residue remaining on the photoreceptor 101 after the toner image transfer. It is shown. FIG. 1 shows a state in which a flicking member 117 that knocks off the adhering matter adhering to the solid lubricant 111 and the rotating brush 116 is disposed at a position in contact with the rotating brush 116, and the blade 113b is attached to the base plate 113a. It is also shown.

  In the image forming apparatus shown in FIG. 1, the surface of the photoconductor is coated with an appropriate amount of lubricant, so that the overall effect of lubrication between the cleaning blade and the surface of the photoconductor is reduced due to the lubrication effect between the cleaning blade and the surface of the photoconductor. Therefore, it is intended to suppress an increase in frictional force between them.

  However, it has been reported that even if the above proposal is adopted, the frictional force on the end side of the photoreceptor cannot be reduced.

  This is because when the toner image is transferred, the lubricant adheres to the toner and the lubricant is also transferred to the transfer object. However, the frequency of the toner image being formed at the end of the photoconductor is lower than that in the central portion. This is because the amount of lubricant transferred from the surface of the photoconductor along with the transfer becomes smaller at the end than at the center, resulting in an excessive amount of lubricant at the end. If the amount is excessive, the above-described lubricating effect is reduced, and the external additive can hardly pass between the cleaning blade and the surface of the photoreceptor, and the frictional force increases.

  Therefore, a proposal has been made to limit the amount of lubricant applied to the photoconductor at the end compared to the center (see Patent Document 1).

  FIG. 2 shows a solid lubricant used in Patent Document 1.

In the solid lubricant 120 shown in FIG. 2, the lower surface 120a in FIG. 2 is used as a surface on which the lubricant is scraped off by the rotating brush, and the proposal in Patent Document 1 shows the shape of the solid lubricant in FIG. As shown in the figure, the surface scraped by the rotating brush is dented at both ends rather than the central portion, so that the scraping of the lubricant by the rotating brush is reduced at both ends compared to the central portion, thereby It is intended to keep the amount of lubricant at the end of the proper amount.
JP 2000-242135 A

  However, since the solid lubricant shown in FIG. 2 has a complicated shape compared to the solid solid lubricant shown in FIG. .

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an image forming apparatus in which a device for limiting the amount of lubricant supplied to both ends of an image carrier as compared with a central portion is achieved.

In order to achieve the above object, an image forming apparatus of the present invention comprises:
An electrostatic latent image is obtained on the surface of the image carrier that rotates about a predetermined rotation axis, and the electrostatic latent image is developed using a developer containing toner to form a toner image on the surface of the image carrier. In the image forming apparatus for forming an image composed of the fixed toner image on the recording medium by finally transferring and fixing the toner image on a predetermined recording medium,
A cleaning blade that scrapes off the residue remaining on the surface after the toner image on the surface of the image carrier is transferred to the surface,
A shaft arranged in parallel to the rotation axis; and a hair portion in which bristles extending radially from the shaft are arranged in a line with the tip positions aligned in the extending direction of the shaft. A brush that rotates around the shaft in contact with the surface of the image carrier, and a solid lubricant that faces the portion of the shaft provided with the hair and contacts the tip of the hair. Comprising a lubricant supply member,
The shaft is characterized in that the diameter of both ends in the extending direction of this portion is smaller than the diameter of the central portion in the extending direction of the portion.

  In the image forming apparatus of the present invention, the shaft diameters at both ends of the bristles of the brush are made smaller than the shaft diameter at the center, so that the lengths of the hairs at both ends of the bristles are reduced. In this way, the tip force of the bristles at both ends of the bristles is smaller than the tip force of the bristles at the center. Therefore, according to the image forming apparatus of the present invention, the supply amount of the lubricant to the both ends of the image carrier by the both ends of the hair, without making the shape of the solid lubricant as shown in FIG. The amount of lubricant supplied to the central portion of the image carrier by the central portion of the bristles can be reduced. By doing so, for example, the diameter of the central portion and the diameter of both end portions are the same size, and the parts provided in the both ends and the hair provided in the central portion have different tip force than the case where parts are used. The score can be reduced.

  Here, the lubricant supply member holds the solid lubricant and is rotatably supported via a rotation shaft parallel to the brush, and generates a moment around the rotation shaft. It is preferable that the solid lubricant held by the rotating portion is brought into contact with the brush by the moment generated by the moment generating portion.

  If it does in this way, since a solid lubricant keeps contacting on the said brush, a lubricant can be supplied stably.

  It is also a preferred aspect that the lubricant supply member is provided with a solid lubricant mainly composed of zinc stearate.

  According to the image forming apparatus of the present invention, the amount of lubricant supplied to both ends of the image carrier can be limited as compared with the central portion.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 3 is a schematic configuration diagram of a main part of a printer which is an embodiment of the image forming apparatus of the present invention.

  As shown in FIG. 3, the printer 1 according to the present embodiment includes four image forming units 10Y, 10M, 10C, and 10K. Each image forming unit has a photosensitive element that rotates in the direction of arrow A. Bodies 11Y, 11M, 11C, 11K, chargers 13Y, 13M, 13C, 13K, developing rolls 12Y, 12M, 12C, 12K, primary transfer rolls 20Y, 20M, 20C, 20K, and a rotating brush for supplying lubricant Photoconductor maintenance sections 14Y, 14M, 14C, and 14K in which a cleaning blade, a flicking member, and a solid lubricant are provided are provided. The printer 1 is capable of full-color printing, and the symbols Y, M, C, and K added to the end of each of the above components are yellow, magenta, cyan, and black images, respectively. It is a component for formation. In order to avoid the complexity of the drawing, in FIG. 3, the exposure device for writing the electrostatic latent images on the photoconductors 11Y, 11M, 11C, and 11K is omitted. The printer 1 is also provided with an intermediate transfer belt 30, a secondary transfer roll 40, and a tension roller 31 that circulate in the direction of arrow B.

  A basic image forming operation of the printer 1 will be described.

  First, toner image formation by the yellow image forming unit 10Y is started, and a predetermined charge is applied to the surface of the photoreceptor 11Y rotating in the direction of arrow A by the contact-type charger 13Y. Next, an exposure device (not shown) irradiates the surface of the photoconductor 11Y with exposure light corresponding to a yellow image to form an electrostatic latent image. The electrostatic latent image is developed with yellow toner by the developing roller 12Y to form a yellow toner image on the photoreceptor 11Y. The toner image is transferred to the intermediate transfer belt 30 by the primary transfer roll 20Y.

  Here, in the printer 1, a developer including toner and a magnetic carrier covered with an outer covering agent is used, and development (visualization) of the electrostatic latent image is performed with the toner in the developer. It is.

  The intermediate transfer belt 30 receives the magenta toner image of the next color in accordance with the timing at which the yellow toner image transferred onto the intermediate transfer belt 30 reaches the primary transfer roll 20M of the image forming unit 10M of the next color. A toner image is formed by the magenta image forming unit 10M so as to reach the primary transfer roll 20M. The magenta toner image formed in this way is transferred onto the yellow toner image on the intermediate transfer belt 30 while being superimposed on the primary transfer roll 20M.

  Subsequently, toner image formation by the cyan and black image forming units 10C and 10K is performed at the same timing as described above, and sequentially superimposed on the yellow and magenta toner images of the intermediate transfer belt 30 in the primary transfer rolls 20C and 20K. Is transcribed.

  Thus, the multicolor toner image transferred onto the intermediate transfer belt 30 is finally secondarily transferred to the paper 200 by the secondary transfer roll 40, and the multicolor toner image is conveyed together with the paper 200 in the direction of arrow C, as shown in the figure. A color image is formed on the sheet 200 by being fixed by a fixing device that does not. In the following, since the functions of the image forming units for Y, M, C, and K are the same, the Y (yellow) color image forming unit 10Y will be representatively described.

  FIG. 4 is an enlarged view of the yellow image forming unit shown in FIG.

  The photoreceptor maintenance unit 14Y, which is a component of the yellow image forming unit 10Y shown in FIG. 4, is composed of a housing 140Y, a lubricant supply mechanism 144Y including a solid lubricant 1444Y, and bristles extending radially from the surface of the shaft 1422Y. The rotating brush 142Y has a bristles 1421Y, the flicking member 143Y that knocks off the adhering matter attached to the rotating brush 142Y, and the cleaning blade 141Y made of urethane rubber. The lubricant supply mechanism 144Y includes a rotation shaft 1441Y, a rotation arm 1442Y, a weight 1443Y, and a solid lubricant 1444Y.

  The solid lubricant 1444Y contains zinc stearate as a main component, and is attached to a rotating arm 1442Y that is rotatable about a rotating shaft 1441Y.

  The rotating arm 1442Y is pivotally supported by the rotating shaft 1441Y, and is attached to the rotating arm 1442Y on the side opposite to the solid lubricant 1444Y with the solid weight of the solid lubricant 1444Y and the rotating arm 1442Y interposed therebetween. Due to the weight of the weight 1443Y, a moment in the direction of pressing the solid lubricant 1444Y against the rotating brush 142Y is acting. Therefore, in this printer 1, the amount of lubricant supplied to the photoreceptor 11Y by the rotating brush 142Y can be controlled by changing the weight of the weight 1443Y.

  FIG. 5 is a front view of a rotating brush that supplies a lubricant to the photoreceptor.

  The rotating brush 142Y shown in FIG. 5 has a portion whose diameter changes from a predetermined diameter at the central portion in the extending direction to a predetermined diameter at the end portion in the extending direction that is smaller than a predetermined diameter at the central portion in the extending direction. The shaft 1422Y has a hair portion 1421Y in which bristles extending radially are arranged on the surface excluding both ends of the shaft 1422Y with the tip positions aligned in the extending direction of the shaft. That is, in the rotating brush 142Y shown in FIG. 5, the diameter b at both ends is smaller than the diameter a at the center of the shaft within the range Y where the bristle portion 1421Y is provided.

  FIG. 6 is a distribution diagram of the tip force of the rotating brush.

  FIG. 6 shows that the tip force of the rotary brush 142Y shown in FIG. 5 differs depending on the position of the rotary brush 142Y on the shaft, and the tip force at both ends of the hair portion 1421Y is lower than that at the center portion. It has become. This is because, as shown in FIG. 7, when the diameter of the shaft 1422Y is small, the length of the hair is longer than the large diameter.

  FIG. 7 is a diagram showing the correlation between the length of the bristles and the tip force.

  FIG. 7 shows that the tip force becomes weaker as the length of the hair becomes longer.

  Thus, by using the rotating brush 142Y in which the tip force of the end of the bristle portion 1421Y is weaker than the tip force of the central portion, the lubricant brushed off from the fixed lubricant by the rotating brush 142Y is used. As shown in FIG. 8, the amount is large at the center and small at both ends.

  FIG. 8 is a diagram showing the correlation between the tip force and the amount of scraping of the solid lubricant.

  FIG. 8 shows how the amount of lubricant scraped off increases as the tip force of the brush increases.

  As the amount of lubricant scraped off decreases, the amount of lubricant supplied to the photoreceptor decreases, so the lubricant coverage on the surface of the photoreceptor decreases as shown in FIG.

  FIG. 9 is a diagram showing a correlation between the amount of lubricant scraping and the lubricant coverage.

  FIG. 9 shows that the amount of lubricant supplied to the photoreceptor also decreases when the amount of lubricant shaving decreases.

  Table 1 shown below shows the image quality and the lubricant coverage of the photoconductor 1 together with a comparative example.

  Table 1 shows a case where 10,000 printers were tested using the printer 1 shown in FIG. 3 in an image density of 0%, full color mode, and high temperature and high humidity (28 ° C., 85% RH) (Example). And the case where a running test of 10,000 sheets was performed in the same environment after replacing the rotating brush used in the printer 1 with a conventional one having no diameter change due to the part (comparative example), The evaluation of the cleaning property and the lubricant coverage on the surface of the photoreceptor are shown.

  The lubricant coverage is the Zn coverage when the amount of the analysis value obtained by XPS analysis is 100%, and the evaluation of the cleaning property is a sensory evaluation of the occurrence of color streaks on the print paper.

  From Table 1, it can be considered that in the example, the Zn covering rate of the end portion of the photoconductor was lower (15%) than that of the comparative example (25%), and thus the speed of the cleaning blade was reduced. In the example, it can be seen that the color streaks on the print paper that have been generated since the number of prints exceeds 5000 have been eliminated.

  As described above, according to the printer 1 of the present embodiment, the shaft diameters at both end portions of the bristle portion 1421Y of the rotating brush 142Y are made smaller than the shaft diameter at the central portion, so that both end portions of the bristle portion 1421Y. The supply amount of the lubricant to both ends of the photoreceptor can be reduced more than the supply amount of the lubricant to the center portion of the photoreceptor by the center portion of the hair.

In addition, as a material of the cleaning brush used in the image forming apparatus of the present invention, a known material can be used. Among them, nylon, acrylic or polypropylene is preferable, and among these, nylon is particularly preferable for long-term stability. It is preferable because it is excellent. The fiber thickness of the rotating brush surface is preferably 2 to 17 denier, more preferably 3 to 10 denier. By setting the fiber thickness within the above range, the solid lubricant is scraped off and applied to the photoreceptor. The fiber length on the brush surface not including the raised adhesive layer thickness is preferably 2.5 mm to 7 mm, more preferably 3 mm to 6.5 mm. By setting the fiber length within the above range, the solid lubricant is scraped off and applied to the photoreceptor. The fiber density on the brush surface is preferably 15 × 10 ³ to 200 × 10 ³ fibers / inch ² (23.4 to 310 fibers / mm ² ), more preferably 20 × 10 ³ to 80 × 10 ³ fibers / inch ^2. (31.0 to 124 pieces / mm ² ). It is preferable to make the fiber density within the above range because a uniform lubricant can be applied over a long period of time.

  As a solid lubricant, zinc stearate has a cleavage property and a high effect of improving releasability, so that more effective film formation is possible. Other fatty acid metal salts include cadmium stearate and barium. Metal salts such as lead, iron, nickel, cobalt, copper, aluminum, magnesium: Dibasic lead stearate: Metal salts such as zinc oleate, magnesium, iron, cobalt, copper, lead, calcium: palmitic acid Metal salts such as aluminum and calcium: lead caprylate: lead caproate: zinc linoleate; cobalt linoleate: calcium ricinoleate: metal salts such as ricinoleic acid and zinc, cadmium: and mixtures thereof. Furthermore, a solidified higher alcohol represented by the following formula can also be used.

CH ₃ (CH ₂ ) _x YCH ₂ OH (wherein x is an integer of 18 to 68)

It is a figure which shows the rotating brush for supplying a lubricant. This is a solid lubricant used in Patent Document 1. 1 is a schematic configuration diagram of a main part of a printer which is an embodiment of an image forming apparatus of the present invention. FIG. 4 is an enlarged view of a yellow image forming unit shown in FIG. 3. FIG. 3 is a front view of a rotating brush that supplies a lubricant to a photoreceptor. It is a distribution map of the tip force of a rotating brush. It is a figure which shows the correlation with the length of the hair of a brush, and tip force. It is a figure which shows correlation with tip force and the scraping amount of a solid lubricant. It is a figure which shows the correlation with the amount of scraping of a lubricant, and lubricant coverage.

Explanation of symbols

1 Printer 1
10Y Image forming section 11Y Photoconductor 14Y Photoconductor maintenance section 140Y Housing 141Y Cleaning blade 142Y Rotating brush 1421Y Bristles 1422Y Shaft 143Y Flicking member 144Y Lubricant supply mechanism 1441Y Rotating shaft 1442Y Rotating arm 1443Y Weight 1444Y Solid lubricant

Claims (1)

An electrostatic latent image is formed on the surface of an image carrier that rotates about a predetermined rotation axis, the electrostatic latent image is developed using a developer containing toner, and a toner image is formed on the surface of the image carrier. In an image forming apparatus for forming an image composed of a fixed toner image on the recording medium by forming and finally transferring and fixing the toner image on a predetermined recording medium,
A cleaning blade that scrapes the residue remaining on the surface after the toner image on the surface of the image bearing member is transferred to the surface, by scraping it against the surface;
A shaft disposed in parallel to the rotation axis; and a bristles in which bristles extending radially from the shaft are arranged in a line with the tip positions aligned in the extending direction of the shaft. A brush that rotates around the shaft while being in contact with the surface of the image carrier, and a solid lubricant that faces the portion of the shaft where the bristles are provided and that contacts the tips of the bristles are provided. Comprising a lubricant supply member,
The image forming apparatus according to claim 1, wherein the shaft has a smaller diameter at both ends in the extending direction of the portion than the diameter of the central portion in the extending direction of the portion where the bristles are provided.

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