JP2011237697A - Cleaning device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device and an image forming apparatus that can evenly apply a lubricant on an image carrier surface and protect an image from generating a stripe.SOLUTION: A cleaning device 46 includes a brush 461 contacting a surface of a photoreceptor drum 41 and a lubricant LO contacting the brush 461. The brush 461 comprises a rotation shaft and a plurality of loop-shaped brush furs planted in a surface layer of the rotation shaft. A minimum distance d between loop peaks A of the brush furs in a direction of the rotation shaft of the photoreceptor drum 41 is smaller than 0.75 mm, and an angle formed by the direction of the rotation shaft of the photoreceptor drum 41 and a loop surface of the brush furs is greater than 0 degree and smaller than 45 degree.

Description

  The present invention relates to a cleaning device and an image forming apparatus.

  Conventionally, a cleaning device including a brush and a solid lubricant is known. There is also an image forming apparatus provided with the cleaning device. The brush is installed in contact with the lubricant, and scrapes off the lubricant by contacting with the lubricant. Further, the brush is installed in contact with the image carrier, and the lubricant scraped off by contact with the image carrier is applied to the surface of the image carrier.

By applying the lubricant to the surface of the image carrier, for example, there are the following merits.
The toner image formed on the surface of the image carrier is easily separated by the lubricant and the transferability is improved.
In addition, wear of a cleaning unit (for example, a blade) that contacts the surface of the image carrier and removes foreign matters is suppressed by the lubricant, and the cleaning performance is maintained.
Further, the wear on the surface of the image carrier caused by the contact of the brush or the blade is suppressed by the lubricant, so that a sufficient service life is ensured.

  Here, if the lubricant is applied non-uniformly on the surface of the image carrier, streaks may occur on the image, which is a problem. For example, when the brush is straight hair, the brush hair may retain a large amount of residual toner remaining on the surface of the image carrier, and may not be able to retain the lubricant by the amount of retained residual toner. When the amount of lubricant held on the brush bristles is small, the brush cannot apply a sufficient amount of lubricant to the surface of the image carrier, and as a result, the lubricant is applied unevenly.

FIG. 11 shows the state of the surface of the image carrier when the lubricant is uniformly applied.
FIG. 12 shows the state of the surface of the image carrier when the lubricant is applied unevenly.
As shown in FIG. 11, when the lubricant is uniformly applied in the direction of the image carrier rotation axis, no streak is generated on the image. On the other hand, as shown in FIG. 12, when the lubricant is applied non-uniformly in the image carrier rotation axis direction, streaks are generated on the image.
As a configuration capable of uniformly applying the lubricant, for example, there is a technique shown below.

  Patent Document 1 discloses a configuration in which a leveling member is installed on the downstream side in the rotation direction of the image carrier from the installation position of the brush, and the lubricant on the surface of the image carrier applied by the brush is made uniform by the leveling member. Has been.

  In Patent Document 2, a configuration in which a loop-shaped brush hair can be used to hold more lubricant than residual toner and a thickness of the brush hair are defined so that the brush hair is brought into uniform contact with the surface of the image carrier. A configuration capable of uniformly applying the lubricant is disclosed.

JP 2009-109573 A Japanese Patent Laid-Open No. 10-26916

  However, in the configuration described in Patent Document 1, since the leveling member needs to be newly installed, the cleaning device is increased in size.

  Further, in the configuration described in Patent Document 2, when loop-shaped brush bristles are used, the brush scraping force increases, so that the brush once scrapes off the lubricant once applied by the brush, resulting in the image carrier. In some cases, the lubricant cannot be uniformly applied to the surface. In other words, the lubricant cannot be uniformly applied to the surface of the image carrier only by defining the thickness of the brush hair.

  An object of the present invention is to provide a cleaning device and an image forming apparatus that can uniformly apply a lubricant to the surface of an image carrier and prevent streaks from occurring on an image.

According to the present invention, the cleaning device is provided with a brush that is installed in contact with the image carrier and the lubricant, scrapes the lubricant by rotation, and applies the scraped lubricant to the surface of the image carrier. In the device
The brush comprises a rotating shaft and a plurality of loop-shaped brush bristles planted on the surface layer of the rotating shaft,
The shortest distance between the loop vertices of the bristle in the rotational axis direction of the image carrier is smaller than 0.75 [mm], and is formed by the rotational axis direction of the image carrier and the loop surface of the brush bristle. A cleaning device having an angle greater than 0 [°] and less than 45 [°] is provided.

According to the present invention, in the image forming apparatus including the brush that contacts the surface of the image carrier and the lubricant that contacts the brush.
The brush comprises a rotating shaft and a plurality of loop-shaped brush bristles planted on the surface layer of the rotating shaft,
The shortest distance between the loop vertices of the bristle in the rotational axis direction of the image carrier is smaller than 0.75 [mm], and is formed by the rotational axis direction of the image carrier and the loop surface of the brush bristle. An image forming apparatus having an angle larger than 0 [°] and smaller than 45 [°] is provided.

  According to the present invention, the lubricant can be uniformly applied to the surface of the image carrier, and streaks can be prevented from occurring on the image.

1 is a diagram illustrating a schematic configuration of a color image forming apparatus. It is a figure which shows schematic structure of a cleaning apparatus. It is a figure which shows the enlarged view of a bristle. It is a figure which shows the contact state of the bristle in the case of the pressing force of a brush <the pressing force of a lubricant. It is a figure which shows the contact state of the brush hair in the case of the pressing force of a brush> the pressing force of a lubricant. It is a figure which shows a part of expanded view of the rotating shaft surface layer of a brush. It is a figure which shows a part of expanded view of the rotating shaft surface layer of a brush. It is a figure which shows the Example, comparative example, and experimental result of a brush. Shows brush configuration and experimental results It is a figure which shows the graph which plotted the experimental result. It is a figure which shows the state of the image carrier surface when a lubrication agent is apply | coated uniformly. It is a figure which shows the state of the image carrier surface when a lubricant is applied non-uniformly.

  A cleaning device and an image forming apparatus according to the present embodiment will be described in detail with reference to the drawings. In addition, this embodiment is an example and this invention is not limited to this.

FIG. 1 shows a schematic configuration of a color image forming apparatus 100.
The image forming apparatus 100 includes an automatic document feeder 1, a scanner unit 2, a control unit 3, an image forming unit 4, and a paper feeding unit 5.

  The automatic document transport unit 1 includes a transport path and a transport roller for transporting the document D placed on the mounting tray to a predetermined transport path.

  The scanner unit 2 includes an optical system such as a light source and a reflecting mirror. The scanner unit 2 irradiates the document D that has passed through a predetermined conveyance path or the document D placed on the platen glass, and receives reflected light. . The scanner unit 2 converts the received reflected light into an electrical signal and outputs it to the control unit 3.

  The control unit 3 includes a CPU, a RAM, a ROM, and the like, and the CPU comprehensively controls the operation of the image forming apparatus 100 in cooperation with various programs stored in the RAM or the ROM. For example, the control unit 3 generates image data (Dy, Dm, Dc, Dk) based on the electrical signal from the scanner unit 2, and outputs the generated image data to the image forming unit 4. The control unit 3 controls the operation of the image forming unit 4 to form an image on the paper P.

  The image forming unit 4 includes an image forming unit Y, an image forming unit M, an image forming unit C, an image forming unit K, an intermediate transfer member T, a secondary transfer roller R, a cleaning device TC, and a fixing device F. .

  Each of the image forming units YMCK forms yellow, magenta, cyan, and black toner images on the photosensitive drum, and transfers the toner images of each color of YMCK formed on the photosensitive drum to the intermediate transfer member T (primary transfer).

Hereinafter, the configuration and operation of the image forming unit Y will be briefly described.
Since the configuration and operation of the image forming unit YMCK are the same, the description of the configuration and operation of the image forming unit MCK is omitted.

  The image forming unit Y includes a photosensitive drum 41, a charging device 42, an exposure device 43, a developing device 44, a primary transfer roller 45, and a cleaning device 46.

  The photosensitive drum 41 has a drum shape having a diameter of 60 [mm], and the surface is constituted by a photosensitive layer having a film thickness of 25 [μm]. The photoreceptor layer is composed of an organic semiconductor layer in which a phthalocyanine pigment is dispersed in polycarbonate and a charge transport layer.

  The charging device 42 uniformly charges the photosensitive drum 41. The exposure device 43 removes the charge from the non-image area of the photosensitive drum 41 to form an electrostatic latent image in the image area.

  The developing device 44 is a developing device using a two-component developing system, and supplies toner to the electrostatic latent image formed on the photosensitive drum 41 to form a yellow toner image.

  The primary transfer roller 45 is a foaming roller having a diameter of φ22 [mm] and is installed on the back surface of the intermediate transfer member T, and transfers the yellow toner image formed on the photosensitive drum 41 to the intermediate transfer member T (primary transfer). Transcription).

  The cleaning device 46 removes foreign matters such as residual toner and paper dust remaining on the surface of the photosensitive drum 41 after the primary transfer. The detailed configuration of the cleaning device 46 will be described later (see FIG. 2). The above is the configuration and operation of the image forming unit Y.

  The intermediate transfer member T is a seamless semiconductive resin belt, is applied with a tension of 6 [kgf], and rotates while carrying a toner image of each color of YMCK.

  The secondary transfer roller R is a roller having an outer diameter of φ24 [mm], a nip width of 7 [mm], and YMCK toner images carried by the intermediate transfer member T are conveyed from the paper feeding unit 5. Transfer to the incoming paper P (secondary transfer).

  The cleaning device TC removes foreign matters such as residual toner and paper dust remaining on the surface of the intermediate transfer member T after the secondary transfer.

  The fixing device F heats and pressurizes the second-transferred paper P to fix the toner image on the paper P. Thereafter, the paper P is transported to a predetermined transport path and discharged outside the apparatus.

FIG. 2 shows a schematic configuration of the cleaning device 46.
The cleaning device 46 includes a brush 461, a lubricant application unit 462, and a blade 463.

  The brush 461 is composed of a rotating shaft having an axial diameter of 6 [mm] and an outer diameter of 11.5 [mm] and a plurality of brush bristles planted on the rotating shaft surface layer. Further, the brush 461 is installed so that the brush bristles abut against the photosensitive drum 41 with a pressing force of 2.0 [N]. When the brush bristles abut against the photoconductor drum 41 with a pressing force of 2.0 [N], the contact width of the brush bristles contacting the photoconductor drum 41 is 1.0 [mm]. The outer diameter of the brush 461 may be 12 [mm].

  The brush 461 contacts the surface of the photoconductive drum 41 while rotating in the counter direction with respect to the rotation direction of the photoconductive drum 41, and scrapes off foreign matters remaining on the surface of the photoconductive drum 41. The ratio of the surface speed of the brush 461 to the surface speed of the photosensitive drum 41 is 0.4. The brush 461 is in contact with the solid lubricant LO, and scrapes off the lubricant LO when the lubricant LO is pressed. The brush 461 is applied when the scraped lubricant LO comes into contact with the photosensitive drum 41.

  The lubricant application unit 462 includes a solid lubricant LO and a pressing unit SP, and is installed so that the lubricant LO contacts the brush 461 with a pressing force of 2.2 [N]. For example, zinc stearate is used as the solid lubricant. Further, for example, a spring as shown in FIG. 2 may be used for the pressing portion SP, or a pressing mechanism including a drive motor may be used as another example. When the lubricant LO contacts the brush 461 with a pressing force of 2.2 [N], the contact width of the brush bristles contacting the lubricant LO is greater than 1.0 [mm].

  The blade 463 is made of an elastic member such as silicon rubber or urethane rubber, and is installed so as to come into contact with the rotation direction of the photosensitive drum 41 from the counter direction. Further, the blade 463 is installed downstream of the brush 461 in the rotation direction of the photosensitive drum 41. The blade 463 removes foreign matters still remaining on the surface of the photosensitive drum 41 even when the brush 461 is scraped off. The removed toner is recovered by a recovery screw (not shown).

In FIG. 3, the enlarged view of a bristle is shown.
The brush bristles are constituted by a combined yarn in which two single fibers are bundled, and are planted on the surface layer of the rotating shaft of the brush 461 so that the combined yarn has a loop shape. Further, the bristles are planted at fixed intervals so that the loop vertices A are not too dense and not too sparse. The shortest distance between the loop vertices A will be described later (see FIG. 6).
The material of the bristle is conductive polyester, the yarn resistance is 11.5 [logΩ], the fineness is 210T (decitex) / 48F (filament), the thickness is 2.8 denier, and the fiber density is 180 [kF / inch ^ 2] ], The height of the loop is 3 [mm]. For example, the material of the brush may be nylon or acrylic, and the fiber density may be 120 [kF / inch ^ 2].

[Uniformity by pressing force]
FIG. 4 shows the contact state of the brush bristles when the pressing force N1 of the brush is smaller than the pressing force N2 of the lubricant. When the pressing force N1 of the brush 461 <the pressing force N2 of the lubricant LO, the contact state of the brush hair is the contact width W1 between the brush hair and the photosensitive drum 41 <contact between the brush hair and the lubricant LO. Width W2. That is, only the bristle portion holding the lubricant LO comes into contact with the photosensitive drum 41. When W1 <W2, the brush 461 can sufficiently apply the lubricant to the surface of the photosensitive drum 41, and can apply the lubricant uniformly to the surface of the photosensitive drum 41.

FIG. 5 shows, as a comparative example, the contact state of the brush bristles when the pressing force N1 of the brush> the pressing force N2 of the lubricant.
When the pressing force N1 of the brush 461> the pressing force N2 of the lubricant LO, the contact state of the brush hair is the contact width W1 between the brush hair and the photosensitive drum 41> the contact between the brush hair and the lubricant LO. Width W2. That is, the brush bristle portion that does not hold the lubricant LO comes into contact with the photosensitive drum 41. When W1> W2, the brush 461 may scrape off the lubricant once applied to the surface of the photosensitive drum 41, and may not be able to uniformly apply the lubricant to the surface of the image carrier.

[Uniformity by distance and angle]
FIG. 6 shows a part of a development view of the surface layer of the rotating shaft of the brush 461.
As shown in FIG. 6, loop-shaped brush hairs are planted at a constant pitch on the surface layer of the rotating shaft. The distance d is the shortest distance between the loop vertices A of the bristle in the rotation axis direction, and in FIG. 6, the distance d = 0.71 [mm]. The angle α is an angle formed by the rotation axis direction and the loop surface, and in FIG. 6, the angle α is 36 [°]. By appropriately defining the distance d and the angle α, the lubricant can be uniformly applied to the surface of the photosensitive drum 41.
In FIG. 6, the brush hairs are planted at a constant pitch downwardly, but the present invention is not limited thereto, and may be planted at a constant pitch upward.

FIG. 7 shows a comparative example.
The comparative example shown in FIG. 7 is a part of a development view of the rotating shaft surface layer when the distance d = 0.94 [mm] and the angle α = 36 [°]. In the case of the comparative example shown in FIG. 7, the angle α is the same as that of the embodiment shown in FIG. 6, but the distance d is large. In some cases, the lubricant LO cannot be uniformly applied.

[Experiment 1]
In FIG. 8, the Example and comparative example of the brush 461 are shown.
In addition, the experimental results (presence or absence of streaks on the image) are shown in FIG.

  Example 1 is the structure of the brush 461 in this embodiment.

Comparative Example 1 has a brush configuration in which the brush hairs are thinner than the brush 461.
Comparative Example 2 has a brush configuration in which the brush hair is thicker than that of the brush 461.
Comparative Example 3 has a brush configuration in which the fiber density is lower than that of the brush 461.
Comparative Example 4 has a brush configuration in which the outer diameter is smaller than that of the brush 461.
Comparative Example 5 has a brush configuration in which the outer diameter is larger than that of the brush 461.

  The comparative example 6 has a brush configuration in which the outer diameter is smaller than that of the brush 461, and the pressing force of the lubricant is maintained while the pressing force N1 of the brush is smaller than the pressing force N2 of the lubricant (see FIG. 4). In this configuration, the pressure N2 is reduced.

  The comparative example 7 has a brush configuration in which the outer diameter is larger than that of the brush 461, and the pressing force of the lubricant is maintained while maintaining the pressing force N1 of the brush <the pressing force N2 of the lubricant (see FIG. 4). In this configuration, the pressure N2 is increased.

  Comparative Example 8 is a brush configuration in which the bristles are thicker, the density is reduced, the outer diameter is increased, the distance d is increased, and the angle α is increased as compared with the brush 461. N1> A configuration in which the state of the pressing force N2 of the lubricant (see FIG. 5) is maintained.

  Comparative Example 9 is a brush configuration in which the material of the bristle is made of conductive nylon, the bristle is thicker, the density is smaller, and the outer diameter is larger than the brush 461, and the pressing force N1 < In this configuration, the pressure N1 of the brush is reduced while maintaining the state of the pressure N2 of the lubricant (see FIG. 4).

  In addition, about the other structure of Comparative Examples 1-9 which is not illustrated in FIG. 8, it is the same as that of Example 1 which concerns on this embodiment.

An experiment was conducted to determine whether or not streaks occur on an image when an A3 document having a printing rate of 0.5% is continuously passed by the image forming apparatus using the brush and the cleaning device having the above-described configuration.
As a result of the experiment, in the case of Example 1, no streak was generated on the image. In Comparative Examples 1 to 7, streaks were slightly generated on the image. In Comparative Examples 8 and 9, clear streaks were generated on the image.

  As described above, according to Experiment 1, by making the contact width W2 between the brush 461 and the lubricant LO larger than the contact width W1 between the brush 461 and the photoconductor drum 41, the photoconductor drum 41 is obtained. Lubricant LO can be uniformly applied to the surface, and streaks can be prevented from occurring on the image.

  Further, by setting the brush 461 and the lubricant LO so that the pressing force N1 of the brush 461 <the pressing force N2 of the lubricant LO (see FIG. 4) is maintained, the contact width W1 <contact width W2. It is possible to prevent streaks from occurring on the image.

  Further, by defining the thickness of the brush hair to 2 to 4 denier, the fiber density to 100 to 180 [kf / inch ^ 2], and the outer diameter of the brush 461 to 11 to 12 [mm], the contact width W1 <contact The width W2 can be set, and streaks can be prevented from occurring on the image.

  Further, by defining the pressing force N2 of the lubricant LO within the range of 0.7 [N] to 2.5 [N], the contact width W1 <contact width W2 can be established, and streaks are generated on the image. Can be prevented.

[Experiment 2]
FIG. 9 shows the brush configuration and experimental results (presence or absence of streaks on the image).
The brush configurations 1 to 4 are brush configurations in which the shortest distance d between the loop apexes A is 0.5 [mm]. Further, in the brush configurations 1 to 4, the angles α formed by the rotation axis direction and the loop surface are different from α = 0 [°], 36 [°], 45 [°], and 50 [°], respectively.

  The brush configurations 5 to 8 are brush configurations in which the distance d is d = 0.71 [mm]. Further, the brush configurations 5 to 8 are configurations in which the angle α is different from α = 0 [°], 36 [°], 45 [°], and 70 [°], respectively. The brush configuration 6 is the same configuration as the brush 461 according to the present embodiment.

  The brush configurations 9 to 12 are brush configurations in which the distance d is d = 0.75 [mm]. Further, the brush configurations 9 to 12 are configured such that the angle α is different from α = 0 [°], 36 [°], 45 [°], and 50 [°], respectively.

  The brush configuration 13 is a brush configuration in which the distance d is d = 0.8 [mm]. Further, the brush configuration 13 is a configuration in which the angle α is α = 36 [°].

  The brush configurations 14 to 17 are brush configurations in which the distance d is d = 0.94 [mm]. Further, the brush configurations 14 to 17 are configurations in which the angle α is different from α = 0 [°], 36 [°], 45 [°], and 50 [°], respectively.

  About the other structure of the brush structures 1-17 which are not illustrated in FIG. 9, it is the same as that of the brush 461 which concerns on this embodiment.

  An experiment was conducted to determine whether or not streaks occur on an image when an A3 document having a printing rate of 0.5% is continuously passed by the image forming apparatus using the brush and the cleaning device having the above-described configuration.

  The experimental result obtained by each structure (1-17) is shown in the figure. Moreover, the figure which plotted the experimental result shown in the figure on the graph is shown in FIG.

FIG. 10 shows a graph plotting the experimental results.
The vertical axis represents the angle α, and the horizontal axis represents the distance d. Further, among the plots (◯, Δ, ×) shown in FIG. 10, ○ indicates no streaks on the image, Δ indicates a slight streak on the image, and x indicates clearly streaks on the image.
According to the graph shown in FIG. 10, the boundary line where the streak is generated / not generated on the image is between 0.75 [mm] to 0.8 [mm] for the distance d and 36 [° for the angle α. ] To 45 [°].

  As described above, according to Experiment 2, the bristles were planted on the surface layer of the rotating shaft so as to satisfy the relationship of the distance d <0.75 [mm] and the angle α <45 [°]. By using a brush, the lubricant LO can be uniformly applied to the surface of the photosensitive drum 41, and streaks can be prevented from occurring on the image.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 1 Automatic document conveyance part 2 Scanner part 3 Control part 4 Image forming part 41 Photosensitive drum 46 Cleaning apparatus 461 Brush 462 Lubricant application part 5 Paper feeding part

Claims (5)

In a cleaning apparatus provided with a brush that is installed in contact with an image carrier and a lubricant, scrapes the lubricant by rotation, and applies the scraped lubricant to the surface of the image carrier.
The brush comprises a rotating shaft and a plurality of loop-shaped brush bristles planted on the surface layer of the rotating shaft,
The shortest distance between the loop vertices of the bristle in the rotational axis direction of the image carrier is smaller than 0.75 [mm], and is formed by the rotational axis direction of the image carrier and the loop surface of the brush bristle. A cleaning device having an angle larger than 0 [°] and smaller than 45 [°].   The cleaning device according to claim 1, further comprising a lubricant pressing portion that presses the lubricant against the brush.   The cleaning device according to claim 1, wherein the lubricant is a solid lubricant.   The cleaning device according to any one of claims 1 to 3, further comprising a cleaning unit that removes foreign matter remaining on the surface of the image carrier on the downstream side in the rotation direction of the image carrier from the installation position of the brush. In an image forming apparatus provided with a brush that contacts the surface of an image carrier and a lubricant that contacts the brush,
The brush comprises a rotating shaft and a plurality of loop-shaped brush bristles planted on the surface layer of the rotating shaft,
The shortest distance between the loop vertices of the bristle in the rotational axis direction of the image carrier is smaller than 0.75 [mm], and is formed by the rotational axis direction of the image carrier and the loop surface of the brush bristle. An image forming apparatus having an angle larger than 0 [°] and smaller than 45 [°].