JP2018004863A - Charging device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging device that uniformly charges a photoreceptor.SOLUTION: A charging device 14 includes a charging brush 20 that charges a photoreceptor drum; the charging brush 20 includes a plurality of types of piles 31 having different lengths and electrostatically implanted in a shaft 30 rotating on shaft center R2; the piles 31 include a plurality of first piles 32, a plurality of second piles 33, and a main pile 34; the plurality of first piles 32 each include a first inclined bristle 32b extending inclined on the upstream side in the rotation direction of the shaft 30; the plurality of second piles 33 each include a second straight bristle 33a extending along the normal of the shaft 30; when the distance from the shaft center R2 to the tip of the first inclined bristle 32b is A, the distance from the shaft center R2 to the tip of the second straight bristle 33a is B, and the distance from the shaft center R2 to the tip of the main pile 34 extending along the normal is C, the maximum amount of biting of the charging brush 20 is set within a range of (B-C) or more and (B-A) or less.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a charging device that charges a photoreceptor and an image forming apparatus including the charging device.

  An electrophotographic image forming apparatus includes a charging device that charges a photoreceptor. The charging device may include a charging brush that rotates in contact with the photoconductor.

  In a charging device using a charging brush, it has been important to adjust the amount (gap) of the charging brush biting into the photoreceptor. This is because it becomes difficult to uniformly charge the photosensitive member when the gap becomes large. That is, in the portion where the charging brush bites most into the photoconductor (non-uniform discharge region), it was not possible to properly discharge the photoconductor from the tip of the charging brush. On the other hand, in a region where the charging brush starts to contact the photosensitive member and a region where the charging brush starts to separate from the photosensitive member (uniform discharge region), substantially uniform discharge can be performed from the charging brush to the photosensitive member. As described above, since the non-uniform discharge area and the uniform discharge area coexist, it is difficult to uniformly charge the surface of the photoreceptor. When image formation was performed in this state, density unevenness occurred in the toner image carried on the photoreceptor.

  There has been proposed a technique that ensures good image formation even when the photosensitive member is charged with a charging brush. For example, the image forming apparatus described in Patent Document 1 includes a charging brush that charges the surface of the photoconductor and an exposure unit that exposes the photoconductor with laser light. The photoreceptor includes a charge generation layer and a charge transport layer on the undercoat layer. The power of the laser light emitted from the exposure means is set to be a predetermined value or more. The above image forming apparatus uses both a specific photoconductor and a charging brush, and uses a specific laser beam, thereby obtaining a sufficiently gradation image free from leakage.

JP 2014-178560 A

  However, the above-described technique has not been able to improve the charging performance of a charging device using a charging brush. That is, there is a possibility that the charging brush cannot uniformly charge the surface of the photoreceptor.

  In order to solve the above-described problems, the present invention provides a charging device that uniformly charges the surface of a photoreceptor and an image forming apparatus including the charging device.

  In order to achieve the above-described object, a charging device of the present invention includes a charging brush that is slidably contacted with a rotating photosensitive member and charges the photosensitive member, and the charging brush is a shaft provided rotatably about an axis. And a plurality of types of piles having different lengths that are electrostatically implanted on the surface of the shaft, and the length of the pile is equal to or longer than the first length and is longer than the first length. The plurality of types of piles include at least a plurality of first piles having the first length and a plurality of second piles having the second length. A plurality of first piles extending along a normal line on the surface of the shaft; and a first upright hair extending in a direction inclined to the upstream side in the rotational direction of the shaft with respect to the normal line of the shaft. A plurality of second slant hairs, The ile includes second upright hairs extending along the normal line of the shaft, and second inclined hairs extending obliquely toward the upstream side in the rotational direction of the shaft with respect to the normal line of the shaft, When the distance from the shaft center of the shaft to the tip of the first slanted hair is A and the distance from the shaft center of the shaft to the tip of the second upright hair is B, the charging to the photosensitive member is performed. The maximum amount of biting of the brush is set in the range of 0 or more and (B−A) or less.

  In order to achieve the above-described object, a charging device of the present invention includes a charging brush that is slidably contacted with a rotating photosensitive member and charges the photosensitive member, and the charging brush is a shaft provided rotatably about an axis. And a plurality of types of piles having different lengths that are electrostatically implanted on the surface of the shaft, and the length of the pile is equal to or longer than the first length and is longer than the first length. The plurality of types of piles include at least a plurality of first piles having the first length and a plurality of second piles having the second length. And the plurality of types of piles include a main pile having the highest usage amount, and the plurality of first piles includes first upright hairs extending along a normal line on the surface of the shaft; The shaft relative to the normal of the shaft First inclined hairs extending obliquely upstream in the rotational direction, and the plurality of second piles have second upright hairs extending along the normal line of the shaft, and the normal line of the shaft A second inclined hair extending obliquely upstream in the rotational direction of the shaft, wherein the distance from the axial center of the shaft to the tip of the first inclined hair is A, and from the axial center of the shaft When the distance to the tip of the second upright hair is B and the distance from the axial center of the shaft to the tip of the main pile extending along the normal line of the shaft is C, The maximum biting amount of the charging brush is set in the range of (BC) or more and (BA) or less.

  In this case, it is preferable to include a rotation mechanism that rotates the charging brush in the same direction as the rotation direction of the photoconductor, and a moving mechanism that reciprocates the charging brush in a direction in which the axis extends.

  In this case, it is preferable to include a power supply circuit that applies a bias having a pulse waveform to the charging brush.

  In order to achieve the above object, an image forming apparatus of the present invention has a single-layer type organic photosensitive layer and is provided so as to be rotatable around a rotation axis, and any one of the above-described charging members. And a charging device described in 1. above.

  According to the present invention, the surface of the photoreceptor can be uniformly charged.

FIG. 2 is a cross-sectional view schematically illustrating the internal structure of the printer according to the embodiment of the invention. 1 is a cross-sectional view schematically showing a drum unit of a printer according to an embodiment of the present invention. 1 is a side view schematically showing a charging device according to an embodiment of the present invention. It is sectional drawing which shows typically the charging brush of the charging device which concerns on one Embodiment of this invention. It is a front view showing typically a part of pile of a charging device concerning one embodiment of the present invention. It is sectional drawing which shows typically the charging brush (gap small) of the charging device which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the charging brush (gap large) of the charging device which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the charging brush (small gap) of the charging device which concerns on the modification of one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the front side of the sheet of FIG. 1 and FIG.

  A printer 1 as an image forming apparatus according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view schematically showing the internal structure of the printer 1. FIG. 2 is a cross-sectional view schematically showing the drum unit 11.

  As shown in FIG. 1, the printer 1 includes an apparatus main body 2 that forms a substantially box-like appearance. A paper feed cassette 3 is detachably provided at the lower portion of the apparatus main body 2. The sheet feed cassette 3 accommodates a sheet S (bundle). A paper discharge tray 4 is provided on the upper surface of the apparatus main body 2.

  The printer 1 includes an image forming unit 5 and a fixing device 6 inside the apparatus main body 2. The image forming unit 5 is provided at an intermediate portion of the conveyance path 7 extending from the paper feed cassette 3 to the paper discharge tray 4. The fixing device 6 is provided on the downstream side of the conveyance path 7 with respect to the image forming unit 5.

  The image forming unit 5 includes a toner container 10, a drum unit 11, and an optical scanning device 12. The toner container 10 stores toner (developer). The drum unit 11 includes a photosensitive drum 13, a charging device 14, a developing device 15, a transfer roller 16, and a toner removing device 17. The charging device 14, the developing device 15, the transfer roller 16, and the toner removing device 17 are arranged around the photosensitive drum 13 in the order of the transfer process. As the toner, a one-component developer made of magnetic toner is used.

  The photoconductor drum 13 as an example of the photoconductor is formed in a cylindrical shape (diameter 30 mm) that is long in the front-rear direction. As shown in FIG. 2, the photosensitive drum 13 is provided so as to be rotatable about a rotation axis R1. The photosensitive drum 13 is configured by laminating a positively charged single layer type organic photosensitive layer 13b on the surface of a drum base tube 13a.

  Although details will be described later, the charging device 14 is provided to charge the surface of the photosensitive drum 13. The developing device 15 is connected to the toner container 10 (see FIG. 1). The developing device 15 includes a developing roller 15 a disposed to face the photoconductive drum 13. The transfer roller 16 is in pressure contact with the photosensitive drum 13 to form a transfer nip. A transfer bias is applied to the transfer roller 16. The toner removing device 17 includes a cleaning blade 17 a that is in sliding contact with the photosensitive drum 13.

  An electrophotographic image forming process will be described. The optical scanning device 12 exposes the charged photosensitive drum 13 to form an electrostatic latent image on the organic photosensitive layer 13b. The toner is supplied from the toner container 10 to the developing device 15 and flies toward the photosensitive drum 13 through the developing roller 15a. Then, the electrostatic latent image carried on the organic photosensitive layer 13b of the photosensitive drum 13 is developed into a toner image. On the other hand, the sheet S is sent from the supply cassette 10 to the conveyance path 7. The toner image is transferred to the sheet S that passes through the transfer nip. The fixing device 6 fixes the toner image on the sheet S. Thereafter, the sheet S is sent out to the paper discharge tray 4. The toner removing device 17 removes toner and charged products remaining on the organic photosensitive layer 13 b of the photosensitive drum 13.

  Next, the charging device 14 will be described with reference to FIGS. FIG. 3 is a side view schematically showing the charging device 14. FIG. 4 is a cross-sectional view schematically showing the charging brush 20.

  As shown in FIGS. 2 and 3, the charging device 14 includes a charging brush 20, a rotating mechanism 21, a moving mechanism 22, and a power supply circuit 23.

  The charging brush 20 is provided for slidingly contacting the rotating photosensitive drum 13 and charging the photosensitive drum 13. The charging brush 20 includes a shaft 30 and a plurality of types of piles 31 (short fibers).

  The shaft 30 is made of a metal such as stainless steel or free-cutting steel, and is formed in a cylindrical shape (diameter 6 mm) that is long in the front-rear direction. Both front and rear ends of the shaft 30 are rotatably supported by the case 24. The shaft 30 is provided to be rotatable about the axis R2.

  The plurality of types of piles 31 are electrostatically flocked on the surface of the shaft 30. As shown in FIG. 4, the charging brush 20 according to the present embodiment includes, for example, three types of piles 31 having different lengths. Specifically, as shown in the upper part of FIG. 4, the plurality of types of piles 31 include a plurality of first piles 32, a plurality of second piles 33, and a plurality of main piles 34. In the present specification, in the description common to the first pile 32, the second pile 33, and the main pile 34, the term and the sign of the pile 31 are simply used.

  The pile 31 is made of conductive nylon having a thickness of 2 denier. That is, the three types of piles 32, 33, and 34 have the same diameter and are formed of the same material. As an example, the length of the pile 31 is set in a range of 2.0 mm (first length) or more and 3.0 mm (second length longer than the first length) or less. The plurality of first piles 32 have a length of 2.0 mm, and the plurality of second piles 33 have a length of 3.0 mm. The plurality of main piles 34 have a length (third length) of 2.5 mm.

The density of the first pile 32 and the density of the second pile 33 are set to, for example, 100 kF / inch ² (kilofilament (number of piles) / square inch). The density of the main pile 34 is set to 150 kF / inch ² , for example. That is, among the plural types of piles 31, the usage amount (the number of pieces used) of the main pile 34 is the largest. The length and density of the pile 31 described above are merely examples, and are not limited thereto, and may be appropriately changed so as to obtain desired charging performance.

  Here, as shown in FIG. 4, the piles 31 are planted on the surface of the shaft 30 in bundles of several to several tens. The bundle of piles 31 is collected at the root (near the surface of the shaft 30). The bundle of piles 31 extends so as to spread radially from the root toward the outside in the radial direction. Therefore, the bundle of piles 31 includes a pile 31 that is substantially upright on the surface of the shaft 30 and a pile 31 that is inclined with respect to the surface of the shaft 30. The pile 31 is mainly provided in a posture inclined to the upstream side in the rotation direction of the shaft 30.

  More specifically, the plurality of first piles 32 includes first upright hairs 32a and first inclined hairs 32b. Similarly, the plurality of second piles 33 include second upright hairs 33a and second inclined hairs 33b. Similarly, the plurality of main piles 34 include main upright hairs 34a and main inclined hairs 34b. The first upright bristles 32a, the second upright bristles 33a, and the main upright bristles 34a are provided so as to extend along the normal line N on the surface of the shaft 30, respectively. The first inclined hair 32b, the second inclined hair 33b, and the main inclined hair 34b are provided so as to be inclined and extend to the upstream side in the rotation direction of the shaft 30 with respect to the normal line N.

  Note that when the electrostatic flocking process is executed, the pile 31 is planted on the surface of the shaft 30 at various angles. That is, the first oblique hair 32b, the second oblique hair 33b, and the main oblique hair 34b are provided at various angles with respect to the normal line N. Accordingly, the inclined hairs 32b, 33b, 34b may be inclined downstream in the rotation direction of the shaft 30. However, in FIG. 4 (and FIG. 5), only the slanted hairs 32b, 33b, and 34b that are inclined toward the upstream side in the rotational direction of the shaft 30 are illustrated for convenience of explanation. For convenience of explanation, unless otherwise specified, the first inclined hair 32b, the second inclined hair 33b, and the main inclined hair 34b are respectively the largest relative to the normal line N on the downstream side in the rotation direction of the shaft 30. It shall refer to the tilted one. Here, as an example, it is assumed that the inclination angle of each of the inclined hairs 32b, 33b, 34b is 30 ° (see FIG. 4). It should be noted that the inclination angle of each of the inclined hairs 32b, 33b, 34b can be appropriately changed so as to obtain a desired charging performance.

  As shown in FIG. 2 or FIG. 3, the rotation mechanism 21 includes a drive motor 21a connected to the charging brush 20 via a first gear (not shown). The first gear meshes with an output gear (not shown) of the drive motor 21 a and an input gear 21 b attached to the shaft 30. The input gear 21b is supported by the shaft 30 so as not to rotate and to be slidable in the axial direction. The drive motor 21a is connected to the photosensitive drum 13 through a second gear (not shown). The drive motor 21a rotates the photosensitive drum 13 and the charging brush 20 clockwise as viewed from the front (see FIG. 2). That is, the rotation mechanism 21 rotates the charging brush 20 in the same direction as the rotation direction of the photosensitive drum 13.

  As shown in FIG. 3, the moving mechanism 22 includes an urging member 40, a fixed bearing portion 41, and a rotating cam 42. The moving mechanism 22 is provided to reciprocate the charging brush 20 in the front-rear direction (direction in which the axis R2 extends).

  The urging member 40 is a so-called coil spring and is disposed so as to be wound around the front end portion of the shaft 30. The rear end portion of the urging member 40 is locked to a locking portion 30 a that protrudes from the surface of the shaft 30. The urging member 40 is disposed in a compressed state between the front side wall 24F of the case 24 and the locking portion 30a. The urging member 40 urges the charging brush 20 (shaft 30) from the front side toward the rear side.

  The fixed bearing portion 41 projects from a cover 24C attached to the rear side wall 24R of the case 24. The fixed bearing portion 41 is formed in a hollow cylindrical shape. An annular fixed cam surface 43 is formed at the front end of the fixed bearing portion 41. The fixed cam surface 43 is formed so as to be inclined when viewed from the side surface.

  The rotating cam 42 is fixed to the rear end portion of the shaft 30 that passes through the rear side wall 24 </ b> R of the case 24. The rotating cam 42 is disposed in the cover 24C. The rotating cam 42 is formed in a stepped cylinder (column). The rotating cam 42 has a cam shaft portion 45 that extends forward from the front end of the cam body 44. An annular rotating cam surface 46 is formed at the step portion between the cam body 44 and the cam shaft portion 45. The rotating cam surface 46 is formed so as to be inclined at the same angle as the fixed cam surface 43 when viewed from the side. The cam shaft portion 45 projects from the rotating cam surface 46 and is rotatably fitted to the fixed bearing portion 41. In a state where the fixed bearing portion 41 pivotally supports the cam shaft portion 45, the rotating cam surface 46 is urged by the urging member 40 and pressed against the fixed cam surface 43.

  The power supply circuit 23 is electrically connected to the charging brush 20. The power supply circuit 23 is provided to apply a bias (voltage) having a pulse waveform to the charging brush 20. The pulse waveform is preferably a rectangular wave.

  The operation of the charging device 14 will be described with reference to FIGS.

  The power supply circuit 23 applies a bias to the charging brush 20. The drive motor 21a rotates the photosensitive drum 13 and the charging brush 20 clockwise as viewed from the front (see arrows in FIG. 2). The charging brush 20 rotates in the counter direction with respect to the photosensitive drum 13 in a state where the pile 31 is in contact with the photosensitive drum 13. For example, the rotational speed (circumferential speed) of the photosensitive drum 13 is set to 160 mm / s. The rotational speed (peripheral speed) of the charging brush 20 is set so that the rotational speed ratio (peripheral speed ratio) with the photosensitive drum 13 is 1.5 (peripheral speed difference 240 mm / s).

  When the charging brush 20 rotates, the urging member 40 and the rotating cam 42 also rotate in the same direction as the charging brush 20. The biasing member 40 always biases the charging brush 20 backward. For this reason, the rotating cam surface 46 of the rotating cam 42 rotates while being in contact with the fixed cam surface 43 of the fixed bearing portion 41.

  For example, when the charging brush 20 rotates in a state where the inclination directions of the fixed cam surface 43 and the rotating cam surface 46 coincide (initial state (see the upper stage in FIG. 3)), the inclination direction of the rotating cam surface 46 is fixed. The cam surface 43 begins to shift in the rotational direction with respect to the tilt direction. The charging brush 20 moves forward against the urging force of the urging member 40 as the inclination directions of the cam surfaces 43 and 46 shift. When the charging brush 20 is rotated half a circle from the initial state, the charging brush 20 is pushed forward most (see the lower part of FIG. 3). When the charging brush 20 rotates more than a half turn from the initial state, the charging brush 20 is urged by the urging member 40 and moves backward. And if it rotates 360 degree | times from an initial state, it will be in the state which the inclination direction with each cam surface 43 and 46 corresponded again.

  As described above, the charging brush 20 reciprocates once in the front-rear direction every rotation. The moving mechanism 22 reciprocates the continuously rotating charging brush 20 in the axial direction. The charging brush 20 vibrates in the front-rear direction with the pile 31 in contact with the surface of the photosensitive drum 13.

  According to the charging device 14 according to the present embodiment described above, the pile 31 of the charging brush 20 slides on the surface of the photosensitive drum 13 in the rotation direction and the axial direction. The charging brush 20 slides on the surface of the photosensitive drum 13 with a pulse waveform bias applied. As a result, the surface of the photosensitive drum 13 (positively charged single layer type organic photosensitive layer 13b) can be effectively charged.

  Incidentally, in the charging device 14 as described above, it is important to adjust the maximum biting amount of the charging brush 20 with respect to the photosensitive drum 13 (hereinafter also referred to as “gap G” (see FIG. 4)). This is because when the gap G is increased, appropriate discharge is not performed on the photosensitive drum 13 from the tip (hair tip) of the pile 31, and the photosensitive drum 13 cannot be uniformly charged. Therefore, the charging device 14 according to the present embodiment exhibits good charging performance with respect to the photosensitive drum 13 by setting the gap G within a predetermined range.

  The gap G of the charging device 14 (charging brush 20) is “the distance at which the tip of the second upright hair 33a can come into contact with the surface of the photosensitive drum 13” from “the tip of the first inclined hair 32b in contact with the photosensitive drum 13”. It is set to a range up to “possible distance”.

  Hereinafter, the range of the gap G will be described in more detail with reference to FIGS. FIG. 5 is a front view schematically showing a part of the pile 31. FIG. 6 is a sectional view schematically showing the charging brush 20 (small gap G). FIG. 7 is a sectional view schematically showing the charging brush 20 (large gap G). 6 and 7, the position of the tip (hair tip) of the pile 31 is indicated by a circle.

  As shown in FIG. 5, let A be the distance from the axis R2 of the shaft 30 to the tip of the first inclined hair 32b (inclination angle 30 °). The tip of the first inclined hair 32b is located closest to the axis R2 in the pile 31. Let B be the distance from the axis R2 of the shaft 30 to the tip of the second upright hair 33a. The tip end of the second upright hair 33a is at a position farthest from the axis R2 in the pile 31. Let C be the distance from the axis R2 of the shaft 30 to the tip of the main upright hair 34a. The distance C is an intermediate length between the distance A and the distance B. In this case, the gap G is set in a range (BC ≦ G ≦ BA) that is not less than (BC) and not more than (BA).

  In this embodiment, since A≈4.7 mm, B = 6.0 mm, and C = 5.5 mm, the gap G is 0.5 mm or more and about 1.3 mm or less (0.5 mm ≦ G ≦ about 1. 3 mm). As shown in FIG. 6, the tip of the first pile 32 (32a, 32b) is separated from the photosensitive drum 13 with the charging brush 20 farthest from the photosensitive drum 13 (gap G = 0.5 mm). Yes. In this state, the tips of the second pile 33 (33a, 33b) and the main upright hair 34a are in contact with the photosensitive drum 13.

  On the other hand, as shown in FIG. 7, with the charging brush 20 most biting into the photosensitive drum 13 (gap G≈1.3 mm), the tip of the second pile 33 (33a, 33b) and the main pile 34 (34a, The tip of 34b) bites into the photosensitive drum 13 slightly. In this state, the tip of the first pile 32 (32a, 32b) is in contact with the photosensitive drum 13.

  By setting the gap G in the above range, the leading end of the first pile 32 is in contact with or close to the surface of the photosensitive drum 13. For this reason, even if the second pile 33 greatly bites into the photosensitive drum 13 to form a non-uniform discharge region, appropriate discharge is performed from the front end of the first pile 32 to the photosensitive drum 13. Thereby, a uniform discharge region can be formed in the portion where the gap G is formed. A region where the second pile 33 or the main pile 34 starts to contact the photosensitive drum 13 and a region where the second pile 33 or the main pile 34 starts to move away from the photosensitive drum 13 are uniform discharge regions. An appropriate discharge is performed from the two piles 33 or the main pile 34 to the photosensitive drum 13. According to the charging device 14 according to the present embodiment described above, a uniform discharge region is formed between the photosensitive drum 13 and the charging brush 20, so that the surface of the photosensitive drum 13 can be uniformly charged. . As a result, a good toner image can be formed on the surface of the photosensitive drum 13.

  In the charging device 14 according to the present embodiment, the usage amount of the main pile 34 is the largest among the plurality of types of piles 31, but the present invention is not limited to this. For example, the pile 31 having the highest usage amount (high density) may be the first pile 32 or the second pile 33. Further, in the charging device 14 according to the present embodiment, the charging brush 20 is configured by three types of piles 31, but the present invention is not limited to this. The charging brush 20 may be composed of two types of piles 31 having different lengths, or may be composed of four or more types of piles 31 having different lengths.

  As shown in FIG. 8, as the charging device 18 according to the modification, for example, when the charging brush 20 includes the first pile 32 and the second pile 33 without the main pile 34, the gap G is 0. It is set in the range above (BA) and below (0 ≦ G ≦ BA). That is, the gap G is set in a range from 0 to “a distance that the tip of the first inclined hair 32b can contact the photosensitive drum 13”. Although a detailed description is omitted, the same applies to the case where the second pile 33 is used in the largest amount.

  As shown in FIG. 8, with the charging brush 20 farthest from the photosensitive drum 13 (gap G = 0), the tip of the first pile 32 is separated from the photosensitive drum 13 and the tip of the second upright hair 33a. Slightly contacts the photosensitive drum 13. On the other hand, in a state where the charging brush 20 is most biting into the photosensitive drum 13 (gap G≈1.3 mm), the tip of the second pile 33 (main pile 34) slightly bites into the photosensitive drum 13, and the first pile 32 is obtained. The front end of the roller contacts the photosensitive drum 13 (see FIG. 7). According to the charging device 18 according to this modification, the same effect as that of the above-described charging device 14 can be obtained.

  In the present embodiment (including modifications (hereinafter the same)), each of the inclined hairs 32b, 33b, and 34b has the same inclination angle. In addition, although the moving mechanism 22 made the biasing member 40 and the cam mechanism (the fixed bearing part 41, the rotation cam 42) cooperate, and vibrated the charging brush 20, this invention is not limited to this. Instead of the moving mechanism 22 described above, the charging brush 20 may be reciprocated using, for example, a solenoid or a linear motor. Further, the moving mechanism 22 may be omitted.

  In the present embodiment, the case where the present invention is applied to the monochrome printer 1 has been described as an example. However, the present invention is not limited thereto, and the present invention may be applied to, for example, a color printer, a multifunction peripheral, a facsimile, and the like. .

  The description of the above embodiment shows one aspect of the charging device according to the present invention and an image forming apparatus including the same, and the technical scope of the present invention is not limited to the above embodiment. The components in the above embodiment can be appropriately replaced or combined with existing components and the like, and the description of the above embodiment does not limit the content of the invention described in the claims. .

1 Printer (image forming device)
13 Photosensitive drum (photosensitive member)
13b Organic photosensitive layer 14, 18 Charging device 20 Charging brush 21 Rotating mechanism 22 Moving mechanism 23 Power supply circuit 30 Shaft 31 Pile 32 First pile 32a First upright hair 32b First inclined hair 33 Second pile 33a Second upright hair 33b Second 2 oblique hair 34 main pile G gap (maximum bite amount)
N Normal R1 Rotation axis R2 Axis center

Claims (5)

A charging brush that is in sliding contact with the rotating photoconductor and charges the photoconductor;
The charging brush is
A shaft provided rotatably around an axis;
A plurality of piles of different lengths electrostatically implanted on the surface of the shaft,
The length of the pile is set in a range not less than a first length and not more than a second length that is longer than the first length;
The plurality of types of piles include at least a plurality of first piles having the first length and a plurality of second piles having the second length,
The plurality of first piles are:
First upright hairs extending along normals on the surface of the shaft;
A first inclined hair extending inclining toward the upstream side in the rotational direction of the shaft with respect to the normal line of the shaft,
The plurality of second piles are:
Second upright hairs extending along the normal of the shaft;
A second inclined hair extending obliquely toward the upstream side in the rotational direction of the shaft with respect to the normal line of the shaft,
When the distance from the shaft center of the shaft to the tip of the first oblique hair is A and the distance from the shaft center of the shaft to the tip of the second upright hair is B, the distance to the photoconductor A charging device, wherein the maximum biting amount of the charging brush is set in a range of 0 or more and (B-A) or less. A charging brush that is in sliding contact with the rotating photoconductor and charges the photoconductor;
The charging brush is
A shaft provided rotatably around an axis;
A plurality of piles of different lengths electrostatically implanted on the surface of the shaft,
The length of the pile is set in a range not less than a first length and not more than a second length that is longer than the first length;
The plurality of types of piles include at least a plurality of first piles having the first length and a plurality of second piles having the second length,
Among the plurality of types of piles, the main pile with the largest amount of use is included,
The plurality of first piles are:
First upright hairs extending along normals on the surface of the shaft;
A first inclined hair extending inclining toward the upstream side in the rotational direction of the shaft with respect to the normal line of the shaft,
The plurality of second piles are:
Second upright hairs extending along the normal of the shaft;
A second inclined hair extending obliquely toward the upstream side in the rotational direction of the shaft with respect to the normal line of the shaft,
The distance from the shaft center of the shaft to the tip of the first inclined hair is A, the distance from the shaft center of the shaft to the tip of the second upright hair is B, and the shaft center of the shaft to the tip When the distance to the tip of the main pile extending along the normal line of the shaft is C, the maximum biting amount of the charging brush with respect to the photosensitive member is (BC) or more and (BA) The charging device is set to the following range. A rotation mechanism that rotates the charging brush in the same direction as the rotation direction of the photoconductor;
The charging device according to claim 1, further comprising: a moving mechanism that reciprocates the charging brush in a direction in which the axis extends.   4. The charging device according to claim 1, further comprising a power supply circuit that applies a bias having a pulse waveform to the charging brush. A photoreceptor having a single-layer type organic photosensitive layer and provided rotatably about a rotation axis;
An image forming apparatus comprising: the charging device according to claim 1 for charging the photosensitive member.

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