JP2008233477A - Coating brush and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating brush capable of applying a lubricant of a proper amount over a long period and capable of removing remaining toner or the like on a photoreceptor, and to provide an image forming apparatus. <P>SOLUTION: The coating brush 32 includes: a shaft 41; a base cloth 42 arranged on the surface of the shaft 41; and brush hairs 43 of loop shape planted on the base cloth 42; wherein a plurality of kinds of hairs having different heights from the surface of the base cloth 42 to the outermost circumference part are used as the brush hairs 43. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus that forms an image using an image carrier and a coating brush used in the image forming apparatus. More specifically, the present invention relates to an application brush and an image forming apparatus for applying a lubricant to an image carrier.

  Conventionally, a lubricant is appropriately applied to an image carrier that carries a toner image. This is mainly for the purpose of improving the releasability of the toner during transfer and for reducing the wear at the rubbing spot due to the cleaning blade or the like. As such a lubricant application device, there is known a device in which a rotating brush is disposed so as to contact both a solid lubricant and an image carrier. In such a case, the solid lubricant is pressed against the brush by a spring force or its own weight. Then, the solid lubricant is scraped off with a brush, and the scraped lubricant is applied to the image carrier.

  In an apparatus for applying such a lubricant, it is required to supply an appropriate amount of lubricant stably over a long period of time. If the coating amount is insufficient, sufficient toner releasability cannot be obtained. On the other hand, if the coating amount is too large, for example, in an image forming apparatus that transfers a toner image from the photoreceptor to the intermediate transfer belt, the lubricant applied to the photoreceptor adheres to the intermediate transfer belt through the photoreceptor. There is. In this case, the releasability of the intermediate transfer belt is increased, which causes the transfer performance from the photoreceptor to the intermediate transfer belt to be decreased.

In general, it is desirable that such a solid lubricant can provide a stable supply amount at least for the life of the image carrier. That is, even if the remaining amount of the lubricant is reduced, it is desired that there is no significant change in the application amount. Therefore, for example, in the lubricant application device described in Patent Document 1, the solid lubricant is pressed against the brush by the weight of the lubricant and the holder. Accordingly, the force for pressing the lubricant against the brush is kept small, the supply amount of the lubricant is suppressed as much as possible, and the hair fall of the brush is also prevented.
JP 2003-57996 A

  However, in the apparatus described in Patent Document 1, since the supply over a long period of time is particularly aimed, the pressing force of the solid lubricant is considerably reduced. Therefore, the amount of lubricant applied to the image carrier is small, and there is a possibility that sufficient release properties of the image carrier cannot be obtained. In addition, since the dead weight is used, it is necessary to dispose the solid lubricant above the brush. For this reason, there is a problem that there is a restriction on the arrangement.

  Further, as one of the functions required for the application brush, there is a function of scraping off foreign matters such as toner remaining on the photosensitive member. Straight hair brushes that consist of straight hairs have high scratchability because only the tips of the brush hairs come into contact with the photoreceptor and solid lubricant, but tend to scrape the solid lubricant locally. It is. For this reason, in particular, when the flock density is low, once the solid lubricant has irregularities, the irregularities are easily promoted. In that case, there was a risk of unevenness in the amount of lubricant applied.

  On the other hand, in the case of the loop brush in which the brush hair is in a loop shape, since a relatively long range of fibers contacts, a relatively uniform contact state can be secured even if the flocking density is low. On the other hand, there is a problem that the function of scraping off foreign matters such as residual toner from the photosensitive member is somewhat inferior because it is relatively soft. On the other hand, it is not preferable to simply increase the hardness of the bristles of the loop brush because the solid lubricant may be excessively shaved.

  The present invention has been made to solve the problems of the above-described conventional apparatus. That is, an object of the present invention is to provide an application brush and an image forming apparatus that can apply an appropriate amount of lubricant over a long period of time and can appropriately remove residual toner and the like on the photoreceptor.

  An application brush of the present invention made for the purpose of solving this problem is an application brush having a shaft, a base fabric disposed on the surface of the shaft, and loop-shaped brush hairs implanted in the base fabric. There are several types of brush bristles with different heights from the surface of the base fabric to the outermost periphery.

  In general, a brush with a long brush hair is soft and a brush with a short brush hair is hard. In the application brush of the present invention, since there are a plurality of types of brush hairs having different heights from the surface of the base fabric to the outermost peripheral portion, the degree of hit can be different depending on which brush hair contacts. . For example, if it arrange | positions in the position where the distance with an application | coating brush differs according to a contact target object, appropriate contact strength can be obtained for each.

  Furthermore, in the present invention, it is desirable that the fiber length of the loop-shaped portion of the bristles varies depending on the type of height. That is, it is desirable that the type of height from the surface of the base fabric of the brush bristle to the outermost periphery is formed by the difference in the fiber length of the bristle itself. If it is in this way, the extent to which the bristle will hit can be adjusted by the fiber length. It is also easy to adjust the distance to the contact object.

  Further, the present invention provides an image having an image carrier, a solid lubricant, a coating brush that scrapes off the solid lubricant and applies the solid lubricant to the image carrier, and a pressing portion that presses the solid lubricant toward the coating brush. A forming apparatus, wherein the application brush has a shaft, a base cloth disposed on the surface of the shaft, and loop-shaped brush bristles implanted in the base cloth, and the brush bristles include a surface of the base cloth. The image forming apparatus includes a plurality of types having different heights from the outermost part to the outermost peripheral part.

  Furthermore, in the present invention, it is desirable that the fiber length of the loop-shaped portion of the bristles varies depending on the type of height.

  Furthermore, in the present invention, the brush hair of the minimum height contacts the image carrier and does not contact the solid lubricant, and the brush hair of the maximum height is applied to both the image carrier and the solid lubricant. It is desirable to make contact. In such a case, the image carrier is relatively strongly hit and the solid lubricant is relatively weakly hit. Accordingly, it is possible to appropriately remove the residual toner and the like on the image carrier, and to prevent the solid lubricant from being excessively shaved. As a result, an appropriate amount of lubricant can be applied over a long period of time.

  Furthermore, in the present invention, it is desirable to have a foreign matter removing member that contacts all types of brush bristles at a position after contact with the image carrier and before contact with the solid lubricant. In this case, foreign matters such as residual toner scraped off from the image carrier are removed from the application brush by the foreign matter removing member.

  According to the application brush and the image forming apparatus of the present invention, it is possible to provide an application brush and an image forming apparatus capable of applying an appropriate amount of lubricant over a long period of time and appropriately removing residual toner and the like on the photoreceptor. thing.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a so-called tandem color image forming apparatus.

  As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes imaging units 12 </ b> Y, 12 </ b> M, 12 </ b> C, and 12 </ b> K for each color arranged along an intermediate transfer belt 11. A secondary transfer roller 13 and an intermediate transfer cleaning unit 14 are also provided around the intermediate transfer belt 11. At the time of image formation, the intermediate transfer belt 11 rotates counterclockwise in the drawing. The imaging units 12Y, 12M, 12C, and 12K have almost the same configuration. Hereinafter, subscripts representing the respective colors are omitted and referred to as an imaging unit 12. In the image forming apparatus 1 of this embodiment, the imaging units 12 are unitized and exchangeable.

  A schematic configuration of the imaging unit 12 is shown in FIG. The imaging unit 12 has a cleaning unit 22, a charging unit 23, an exposure unit 24, and a developing unit 25 with the photoreceptor 21 as the center. In addition, a primary transfer roller 26 is disposed on the opposite side of the photoreceptor 21 with the intermediate transfer belt 11 therebetween (see FIG. 1). Here, the photoconductor 21, the charging unit 23, the exposure unit 24, the developing unit 25, and the primary transfer roller 26 are all used in a general image forming apparatus.

  Further, in this embodiment, as shown in FIG. 2, a cleaning blade 31, an application brush 32, a solid lubricant 33, a holder 34, a pressing spring 35, a flicker 36, and a screw 37 are provided in the housing 30 of the cleaning unit 22. Yes. The cleaning blade 31 is in contact with the photosensitive member 21 at the upper side in the drawing.

  As shown in the cross-sectional view of FIG. 3, the application brush 32 is obtained by looping brush hairs 43 planted on a base cloth 42, wound around the outer periphery of the shaft 41, and bonded. Here, the loop shape is one in which both side portions of the fibers of the brush bristles 43 are fixed to the base fabric 42 and the intermediate portion thereof is lifted from the base fabric 42. The base fabric 42 is, for example, a flat fabric in which fibers made of nylon, polyester, acrylic, or the like having a thickness of about 0.5 mm are woven into a mesh structure. Also, a resin sheet or a rubber sheet can be used as the base fabric. In this figure, the thickness of the base fabric 42 is drawn considerably larger than the other portions.

  As shown in FIG. 4, the application brush 32 of this embodiment has three types (t1, t2, t3) of brush hairs 43 (43a, 43b, 43c) having different fiber heights t. The fiber is knitted into a continuous S-shape on one side. The three types of brush bristles 43 have the same fiber type and thickness, and are formed of, for example, conductive nylon fibers. Here, the fiber height t is the height from the surface of the base fabric 42 to the loop top portion (outermost peripheral portion) of the brush hair 43 in the natural state, and is a half of the fiber length used in one loop. The distance is slightly shorter than 1. That is, the three types of brush hairs 43 have different fiber lengths used for each loop. Further, the fiber height t in this embodiment is the height of the new application brush 32.

  In this embodiment, when the base fabric 43 is wound around the shaft 41, the surface including the loop is made approximately parallel to the axial direction of the shaft 41. In general, since the base cloth 42 is wound around the shaft 41 in a spiral shape, it is desirable that the bristles 43 be arranged obliquely with respect to the base cloth 42 and planted. Further, the flocking density of the three types of brush hairs is not necessarily uniform.

  Further, the application brush 32 is disposed in the housing 30 of the cleaning unit 22 above the cleaning blade 31 in FIG. When the image is formed, the application brush 32 is rotated by the rotation of the photosensitive member 21 and rotated in the direction of rotation as indicated by an arrow in the drawing. That is, the arrangement of the application brush 32 is located upstream of the cleaning blade 31 and downstream of the primary transfer portion with respect to the rotation of the photosensitive member 21.

  The solid lubricant 33 is formed by solidifying a lubricant such as zinc stearate. This is relatively soft. The solid lubricant 33 is formed in the depth direction in FIG. 2 to have the same length as the axial length of the photosensitive member 21, and the right end surface in the figure is fixed to the holder 34. Further, the holder 34 is pressed leftward in the drawing by a pressing spring 35. The right end portion of the pressing spring 35 in the figure is fixed to the housing 30 of the cleaning unit 22. A plurality of pressing springs 35 are arranged in a balanced manner in the axial direction (the depth direction in the drawing) of the application brush 32.

  Further, the flicker 36 has a shape in which one side of a thin plate-like member having some elasticity is bent along the side. The bent left end portion in FIG. 2 is a free end, and the right end portion in the figure is fixed to the housing 30 of the cleaning unit 22. Furthermore, the outer peripheral part of the bent one side is fixed at a position where it comes into contact with the top of the loop of the bristles 43 of the application brush 32. Here, all kinds of brush hairs 43a, 43b, 43c are brought into contact with each other. Thus, when the application brush 32 rotates, all the brush hairs 43a, 43b, 43c are repelled by the flicker 36. Thereby, the adhering matter adhering to the application brush 32 is repelled away.

  The flicker 36 is disposed at a position upstream of the solid lubricant 33 and downstream of the photoreceptor 21 with respect to the rotation direction of the application brush 32. Therefore, the lubricant scraped off by the applying brush 32 is applied to the photosensitive member 21 without being repelled by the flicker 36. On the other hand, deposits such as toner adhering to the application brush 32 by touching the photoreceptor 21 can be removed by the flicker 36. Then, the residual toner and the like that is repelled from the application brush 32 by the flicker 36 is conveyed by the screw 37 in the axial direction (depth direction in FIG. 2). Then, the toner is collected in a waste toner box provided near the end in the axial direction.

Here, in this embodiment, each part is arranged so that the fiber heights t1, t2, and t3 of the brush bristles 43a, 43b, and 43c of the application brush 32 satisfy the following conditions. That is, as shown in FIG. 5, the shortest distance d1 between the surface of the base cloth 42 of the application brush 32 and the solid lubricant 33 satisfies the following relationship.
d1> t1 and d1 <t3
Further, the shortest distance d2 between the surface of the base cloth 42 of the application brush 32 and the photosensitive member 21 satisfies the relationship of the following equation.
d2 <t1

  In this manner, as shown in FIG. 5, the loop top of the bristle 43 having the lowest fiber height t (brush bristle 43a) contacts the surface of the photoreceptor 21, but the solid lubricant. It does not contact the surface of 33. On the other hand, the loop top portion of the brush bristle 43 having the highest fiber height t (brush bristle 43 c) is in contact with both the photoreceptor 21 and the surface of the solid lubricant 33.

  In general, in such a brush, when the fiber height t is low, the rigidity of the fiber is large and the scraping property is large. When the fiber height t is high, the rigidity of the fiber is small and the scraping property is small. Here, the brush hair 43a having the fiber height t1 has a high scraping property, and the brush hair 43c having the fiber height t3 has a small scraping property. In this embodiment, since the brush bristles 43a having a high scraping property are not in contact with the solid lubricant 33, the solid lubricant 33 is not excessively shaved and an appropriate amount can be applied over a long period of time. On the other hand, since the brush bristles 43a, 43b, and 43c having fiber heights t1 to t3 are all in contact with the photoconductor 21, the scraping property as a whole is large. Therefore, residual toner and the like on the surface of the photoreceptor 21 can be reliably collected.

  Next, an image forming method by the image forming apparatus 1 of this embodiment will be described. At the time of image formation, the photosensitive member 21 rotates clockwise in FIG. The charging unit 23 charges the surface of the photoreceptor 21 almost uniformly. Next, the exposure unit 24 performs exposure based on the image data, and an electrostatic latent image is formed on the surface of the photoreceptor 21. Further, the electrostatic latent image is developed in the developing unit 25, and a toner image is formed on the surface of the photoreceptor 21. The formed toner image is transferred to the intermediate transfer belt 11 by the primary transfer roller 26 (see FIG. 1). The toner remaining on the photoreceptor 21 after the transfer is scraped off by the cleaning blade 31 of the cleaning unit 22.

  At this time, the application brush 32 is disposed so that all of the bristles 43 a, 43 b, 43 c are in contact with the photoreceptor 21. Therefore, the photoconductor 21 rotates and rotates counterclockwise in FIG. The solid lubricant 33 is pressed against the application brush 32 by the pressing spring 35 until it contacts the brush bristles 43c. Therefore, the loop tops of the brush bristles 43c of the application brush 32 are alternately brought into contact with the surface of the photoreceptor 21 and the surface of the solid lubricant 33 by rotation.

  Therefore, the application brush 32 scrapes an appropriate amount of the solid lubricant 33 on the right side in FIG. 2 and applies it to the photoreceptor 21 on the left side. Since the photoconductor 21 and the application brush 32 are rotated, the lubricant is uniformly applied to the surface of the photoconductor 21. Thereafter, the portion of the photoreceptor 21 to which the lubricant is applied further rotates and contacts the cleaning blade 31. As a result, the lubricant applied by the application brush 32 becomes a film that is more evenly applied.

  Note that due to the arrangement of the application brush 32, when the application brush 32 comes into contact with the photoconductor 21, residual toner or the like is attached to the photoconductor 21. Since all the brush bristles 43a, 43b, and 43c are in contact with the photosensitive member 21, the application brush 32 can appropriately scrape residual toner and the like adhering to the surface of the photosensitive member 21. The scraped residual toner or the like is repelled and removed from the brush bristles 43 when the rotated application brush 32 contacts the flicker 36.

  Next, the present inventors investigated the effects of the type of application brush on cleaning properties, transfer failure, and toner roll formation. Here, a bizhub C450 manufactured by Konica Minolta Business Technologies (A4Y 35 MFP / min MFP) was used as a testing machine. The test was conducted by modifying the application brush of the cleaning section with the following five types of brushes.

Example: Three-stage loop hair having fiber heights of 1.5 mm, 2.0 mm, and 2.5 mm
Flocking density 100 / (25.4mm) ²
Comparative Example 1: Three stages of straight hair with fiber heights of 1.5 mm, 2.0 mm, and 2.5 mm
Flocking density 100 / (25.4mm) ²
Comparative Example 2: Three-stage straight hair with fiber heights of 1.5 mm, 2.0 mm, and 2.5 mm
Flocking density 430 / (25.4mm) ²
Comparative Example 3: One-stage loop hair having a fiber height of 2.5 mm
Flocking density 100 / (25.4mm) ²
Comparative Example 4: One-stage loop hair having a fiber height of 1.5 mm
Flocking density 100 / (25.4mm) ²
The application brush 32 used here is a brush of conductive nylon fibers (Young's modulus 1000 to 1700 N / mm ² ) having a shaft diameter of 6 mm and a base fabric thickness of 0.5 mm. The flocking density corresponds to the number of flocked portions of the brush bristles 43 that are flocked per one inch square of the base fabric 42.

  The amount of biting of the photosensitive member 21 with respect to the application brush was set to a position where the shortest fiber bites in about 0.5 mm. In the examples and comparative examples 1 and 2, the longest fiber bites in by 1.5 mm. Further, the amount of biting was 1.5 mm in Comparative Example 3 and 0.5 mm in Comparative Example 4. The coating brush rotated with the photoreceptor 21 and rotated with a linear velocity ratio of about 0.7. The solid lubricant 33 had a pencil hardness equivalent to HB, and the pressing force to the coating brush was set to 5 N / m. The contact force of the cleaning blade 31 to the photosensitive member 21 was 23 N / m. In Examples and Comparative Examples 1 and 2, it was confirmed that only the longest fibers were in contact with the solid lubricant 33.

  In this test, first, in the test machine equipped with each of the above-described application brushes, A4Y was endured until the photoconductor 21 having a diameter of 30 mm rotated 100K in the single-sheet intermittent mode (about 10K sheets passed). During this durability, a chart of 20% in total was printed with an image density of 5% in an environment of 23 ° C. and 65% (NN environment).

Next, as a cleaning property test, a solid untransferred image was passed in an environment of 10 ° C. and 15% (LL environment), and it was visually confirmed whether or not the toner passed through the cleaning blade. The evaluation criteria for the cleaning property were as follows.
○ When toner slip-through could not be confirmed
Slightly slipped but not affected by image quality
When slipping through can be confirmed visually ×

Further, as a transfer failure test, a solid image was transferred to a sheet in the same LL environment, and the presence or absence of image density unevenness was visually confirmed. The evaluation criteria for transfer defects were as follows.
○ When no image density unevenness was confirmed
Slightly uneven, but △ when there is no effect on the overall image quality
When image density unevenness can be clearly confirmed ×

In addition, as a toner roll test, the applied brush after durability was taken out and visually confirmed. Toner roll formation is a phenomenon in which a large amount of toner accumulates on the coating brush and becomes solidified with toner. The evaluation criteria for the toner roll were as follows.
○ When toner roll is not allowed
When toner roll is permitted ×
In addition, as a comprehensive evaluation, “good” was given for “cleaning”, “transfer defect”, and “toner roll”. At least one with x or Δ was taken as x.

  The test results were as shown in Table 1 above. All the examples other than the examples were unsatisfactory in any performance. In all evaluations, only the examples were rated as ○.

  As described above in detail, according to the image forming apparatus 1 of the present embodiment, the application brush 32 has the three types of fiber-shaped brush bristles 43 having different fiber heights, and the solid lubricant 33 has the longest length. Only the brush hair 43c contacts. Accordingly, the scraping force for scraping off the solid lubricant 33 is small, and an appropriate amount of lubricant can be applied over a long period of time. Further, since all the brush hairs 43a, 43b, 43c are in contact with the photosensitive member 21, it can be scraped off with a relatively strong force. Therefore, residual toner and the like adhering to the photoconductor 21 can be appropriately removed. As a result, an image forming apparatus that can apply an appropriate amount of lubricant over a long period of time and can appropriately remove residual toner and the like on the photoreceptor.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, the application brush 32 is not limited to a conductive nylon fiber, and may be a brush made of synthetic fiber such as rayon or acrylic. Alternatively, metal fiber may be used. Moreover, not only conductive fiber but insulating fiber may be used. Moreover, it is good also as what is different in the kind and thickness of a fiber with the bristle 43 from which length differs. Alternatively, the flocking density may be different. Further, in this embodiment, the loop bristles having three kinds of fiber heights are used, but a brush having two or four or more kinds of fiber bristles may be used.

  The solid lubricant 33 is not limited to zinc stearate, and various fatty acid metal salts such as magnesium stearate and lithium stearate can be used. Further, the present invention can be applied not only to a tandem color image forming apparatus but also to an image forming apparatus such as a copying machine, a printer, and a FAX, or a monochrome image forming apparatus.

1 is a schematic configuration diagram of a main part of an image forming apparatus according to an embodiment. It is a schematic block diagram of the imaging unit which concerns on this form. It is a schematic sectional drawing of an application brush. It is explanatory drawing which shows the example of the flocked state of the bristle of an application brush. It is explanatory drawing which shows arrangement | positioning of an application brush.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 21 Photoconductor 32 Application brush 33 Solid lubricant 35 Pressing spring 36 Flicker 41 Shaft 42 Base cloth 43 (43a, 43b, 43c) Brush hair

Claims (6)

In an application brush having a shaft, a base fabric disposed on the surface of the shaft, and loop-shaped brush bristles planted on the base fabric,
An application brush characterized in that the brush bristles include a plurality of types having different heights from the surface of the base fabric to the outermost periphery. The application brush according to claim 1,
An application brush characterized in that the fiber length of the loop-shaped portion of the brush bristles varies depending on the type of height. In an image forming apparatus having an image carrier, a coating brush that scrapes off and applies a solid lubricant to the image carrier, and a pressing portion that presses the solid lubricant toward the coating brush, the coating brush includes:
A shaft, a base cloth disposed on the surface of the shaft, and loop-shaped brush bristles implanted in the base cloth;
2. The image forming apparatus according to claim 1, wherein the brush bristles include a plurality of types having different heights from the surface of the base cloth to the outermost periphery. The image forming apparatus according to claim 3,
An image forming apparatus, wherein a fiber length of a loop-shaped portion of the bristle is different depending on a type of height. The image forming apparatus according to claim 3,
The brush hair of the minimum height contacts the image carrier and does not contact the solid lubricant.
The image forming apparatus according to claim 1, wherein the brush bristles having a maximum height are in contact with both the image carrier and the solid lubricant. The image forming apparatus according to claim 5,
An image forming apparatus comprising: a foreign substance removing member that contacts all types of the brush bristles at a position after contacting the image carrier and before contacting the solid lubricant in the coating brush.

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