JP6060052B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus including a cleaning member for removing foreign matters such as residual toner attached to a photosensitive drum has been known (see, for example, Patent Document 1). As shown in FIG. 6, the image forming apparatus includes a cleaning blade 131 and a pre-charging cleaning sheet 124 as cleaning members. The cleaning blade 131 is disposed downstream of the developing roller 127a in the drum rotation direction. The cleaning blade 131 scrapes off foreign matter on the peripheral surface by bringing its tip into contact with the peripheral surface of the photosensitive drum 121.

  In the upstream portion of the cleaning blade 131 in the drum rotation direction, an external toner additive such as silica or titanium oxide is combined with the paper powder to grow into an aggregate. For example, when the photosensitive drum 121 is started up, the aggregate is dragged by the tip of the cleaning blade 131 toward the peripheral surface of the photosensitive drum 121 and bent to pass downstream of the drum 131 in the drum rotation direction. Leak. The pre-charging cleaning sheet 124 plays a role of capturing the leaked aggregate so as not to adhere to the charging roller 123a. Specifically, the pre-charging cleaning sheet 124 is disposed downstream of the cleaning blade 131 in the drum rotation direction and upstream of the charging roller 123a in the drum rotation direction. The pre-charging cleaning sheet 124 captures the agglomerates by bringing the leading end thereof into contact with the peripheral surface of the photosensitive drum 121.

  Seal members 135 are provided at both ends of the cleaning blade 131 in the drum axial direction. The seal member 135 has a function of preventing foreign matter from leaking out from both ends of the cleaning blade 131.

  The developing roller 127a is connected to the rotary shaft 127c so as to rotate together. Spacing rollers 127b are supported at both ends of the rotating shaft 127c. Each spacing roller 127b rotates while contacting the peripheral surface of the photosensitive drum 121, thereby holding the distance between the axes of the photosensitive drum 121 and the developing roller 127a at a predetermined distance.

JP 2007-248865 A

  However, in the conventional image forming apparatus described above, the aggregate (foreign matter) captured by the pre-charging cleaning sheet 124 (second cleaning member) leaks from the both ends in the drum axis direction to the downstream side in the drum rotation direction. There is a case. The leaked foreign matter reaches the upstream portion of the seal member 135 in the drum rotation direction and accumulates there. When the amount of accumulated foreign matter exceeds a predetermined amount, the foreign matter enters between the seal member 135 and the peripheral surface of the photosensitive drum 121. As shown by the thick arrows in FIG. 6, the foreign matter that has entered is dammed up by the cleaning blade (first cleaning member) 131, and then moves to the outside in the drum axial direction and is further downstream in the drum rotation direction than the seal member 135. Leak to the side. When the leaked foreign matter adheres to the peripheral surface of the spacing roller 127b connected to the developing roller 127a, the distance between the axes of the developing roller 127a and the photosensitive drum 121 becomes larger than a preset value, and the length increases. However, there is a problem that the image quality of the printed image is deteriorated.

  On the other hand, it is conceivable that the spacing roller 127b provided on the developing roller 127a is arranged outside the seal member 135 in the drum axial direction. However, in this case, since the length of the rotating shaft 127c that supports the developing roller 127a as well as the length of the photosensitive drum 121 in contact with the interval maintaining roller 127b in the drum axial direction needs to be increased, the entire apparatus is large. There is a problem of becoming.

  The present invention has been made in view of such points, and an object of the present invention is to prevent foreign matter leaking from both ends of the second cleaning member in the drum axial direction while preventing the entire image forming apparatus from becoming large. This is to prevent the photosensitive drum and the developing roller from adhering to the spacing roller.

An image forming apparatus according to the present invention has a photosensitive drum having a photosensitive layer on a peripheral surface, and is disposed to face the photosensitive drum, and charges the peripheral surface by contacting the peripheral surface of the photosensitive drum. A charging roller, an exposure device that forms an electrostatic latent image by exposing the peripheral surface of the photosensitive drum charged by the charging roller, and the photosensitive drum; A developing roller for developing the electrostatic latent image on the surface; and a roller disposed downstream of the developing roller in the drum rotation direction, and contacting the peripheral surface of the photosensitive drum to scrape off foreign matter on the peripheral surface. One cleaning member, disposed downstream of the first cleaning member in the drum rotation direction and upstream of the charging roller in the drum rotation direction, and in contact with the circumferential surface of the photosensitive drum, surface A second cleaning member for trapping foreign matter, is connected to the developing roller, for holding the developing roller and the center distance of the photosensitive drum at a predetermined distance by rotating in contact with the peripheral surface of the photosensitive drum A pair of spacing rollers, and a pair of seal members that respectively seal both ends of the first cleaning member in contact with the photosensitive drum in the drum axial direction.

Then, when the portion that is not sealed by the seal member in the contact portion of the first cleaning member with the photosensitive drum is an effective scraping portion, both ends of the second cleaning member in the drum axial direction are the effective scraping drum shaft direction of 1mm or more than both ends in the section, 3 mm located inside the inner end of the drum shaft direction in the pair of spacing rollers, rather than both ends of the drum shaft direction in the effective cleaning unit As described above, it is located outside.

  According to this configuration, both ends of the second cleaning member in the drum axial direction are located inside the both ends of the effective scraping portion of the first cleaning member in the drum axial direction. Accordingly, the foreign matter leaked from both ends of the second cleaning member in the drum axial direction to the downstream side in the drum rotation direction eventually reaches the effective scraping portion of the first cleaning member and is scraped off by the effective scraping portion. Accordingly, it is possible to prevent foreign matters leaking from both ends of the second cleaning member from being accumulated on the upstream side portion of the seal member in the drum rotation direction. As a result, it is possible to prevent the accumulated foreign matter from leaking from between the seal member and the peripheral surface of the photosensitive drum to the downstream side in the drum rotation direction and adhering to the peripheral surface of the spacing roller. Therefore, it is possible to improve the image quality of the printed image by keeping the distance between the axes of the photosensitive drum and the developing roller constant.

  Further, since it is not necessary to dispose the spacing roller connected to the developing roller on the outer side in the drum axis direction than the seal member, the entire apparatus is not enlarged.

According to this configuration, the spacing roller is located outside the inner ends of the pair of seal members and inside the outer ends of the pair of seal members in the drum axis direction. Therefore, foreign matter leaked from the seal member is likely to adhere to the peripheral surface of the spacing roller, and the present invention is particularly useful for such a configuration. And according to this structure, compared with the case where the space | interval holding roller connected with the developing roller is arrange | positioned on the outer side of a drum axial direction rather than a pair of seal member, the whole apparatus can be reduced in size.

  In the present specification, “foreign matter” means deposits on the peripheral surface of the photosensitive drum that do not contribute to image formation. Examples of the foreign matter include residual toner that has been transferred to the paper and left on the peripheral surface of the photosensitive drum in a misaligned manner, and aggregates of paper powder and external additives such as silica and titanium oxide contained in the residual toner. Can be mentioned.

  It is preferable that both ends of the second cleaning member in the drum axis direction are located outside of both ends of the charging roller in the drum axis direction.

  According to this configuration, it is possible to reliably capture the foreign matter from the upstream side in the drum rotation direction of the charging roller toward the charging roller by the second cleaning member. Therefore, it is possible to prevent foreign matters from adhering to the peripheral surface of the charging roller, and to improve the image quality of the printed image.

  According to the present invention, while maintaining the interval between the photosensitive drum and the developing roller, foreign matters leaking from both ends of the second cleaning member in the drum axial direction can be prevented while preventing the entire image forming apparatus from becoming large. It is possible to prevent adhesion to the roller.

It is the schematic sectional view seen from the front side which shows a laser printer as an image forming device in an embodiment. It is an expanded sectional view which shows the image formation part of a laser printer. It is a perspective view which expands and shows a side seal. FIG. 4 is a development view showing the arrangement of cleaning members and various rollers arranged around the photosensitive drum. The result of investigating the presence or absence of foreign matter adhering to the spacing roller when the size relationship between the width of the pre-charging cleaning sheet (dimension B) and the width (dimension C) of the effective scraping portion of the cleaning blade is variously changed. It is a table | surface which shows. It is an expanded view which shows arrangement | positioning of the cleaning member arrange | positioned around the photoconductive drum of the laser printer in a prior art example, and various rollers.

  Hereinafter, embodiments will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

"Implementation-shaped state"
-Overall configuration-
FIG. 1 shows a laser printer 1 (hereinafter simply referred to as a printer) as an image forming apparatus in the present embodiment. The printer 1 includes a paper feeding unit 10, an image forming unit 20, a fixing unit 40, a paper discharge unit 50, and a housing 60. A plurality of transport roller pairs 11 to 13 that sandwich and transport the paper P are disposed in the paper transport path L from the paper supply unit 10 to the paper discharge unit 50.

  The paper feeding unit 10 is disposed in the lower part of the housing 60. The paper feed unit 10 includes a paper feed cassette 10a in which sheet-like paper P is accommodated, and a pickup roller 10b for taking out the paper P in the paper feed cassette 10a and sending it out of the cassette. The paper P sent out of the cassette from the paper feed cassette 10 a is supplied to the image forming unit 20 through the transport roller pair 11. The image forming unit 20 transfers a toner image based on predetermined image data to the paper P supplied from the paper supply unit 10 and supplies the transferred paper P to the fixing unit 40. The fixing unit 40 fixes the toner image on the paper P by pressing the paper P supplied from the image forming unit 20 between the fixing roller 40a and the pressure roller 40b. Then, the paper P on which the toner image is fixed by the fixing unit 40 is sent out to the downstream side by both rollers 40a and 40b. The paper P sent out from the fixing unit 40 is discharged to the paper discharge unit 50 on the upper surface of the housing 60 by the plurality of conveying roller pairs 12 and 13.

-Details of image forming unit-
As shown in FIG. 2, the image forming unit 20 includes a photosensitive drum 21 and an exposure device 25. Around the photosensitive drum 21, a charger 23, a developing device 27, a transfer device 29, a cleaning device 30, and a static eliminator 37 are arranged in this order in the counterclockwise direction of the photosensitive drum 21. An exposure position X is set near the downstream side in the drum rotation direction of the charger 23 in the photosensitive drum 21. The exposure device 25 is configured to irradiate light toward the exposure position X.

  The photosensitive drum 21 includes a cylindrical drum main body 21a whose both ends in the axial center direction are closed, and a photosensitive layer 21b formed over the entire circumference on the peripheral surface of the drum main body 21a. Have. The drum body 21a is made of, for example, aluminum. The photosensitive layer 21b is composed of, for example, a positively charged single-layer organic photoreceptor or a multilayer inorganic photoreceptor. The drum body 21a is driven to rotate counterclockwise in FIG. 2 by a motor (not shown).

The charger 23 includes a charging roller 23a and a brush roller 23b. A charging bias is applied to the charging roller 23a. Charger 2 3 uniformly charges the peripheral surface of the photosensitive drum 21 via the charging roller 23a. The peripheral surface of the charging roller 23 a is in contact with the peripheral surface of the photosensitive drum 21. The charging roller 23 a is disposed in parallel to the photosensitive drum 21. The charging roller 23a is configured by covering the shaft with an elastic body. The elastic body is made of, for example, a synthetic rubber that is a semiconductive member.

  The brush roller 23b rotates in contact with the peripheral surface of the charging roller 23a, thereby uniformizing the toner external additive adhering to the peripheral surface. This prevents the toner external additive from adhering to the peripheral surface of the charging roller 23a. The charging roller 23a and the brush roller 23b are accommodated in a charging case 23c. A pre-charging cleaning sheet 24 is fixed to the upstream surface of the charging case 23c in the drum rotation direction. Details of the pre-charging cleaning sheet 24 will be described later.

  The static eliminator 37 is provided upstream of the charger 23 in the drum rotation direction. The static eliminator 37 irradiates the peripheral surface of the photosensitive drum 21 with light, thereby removing residual charges on the peripheral surface of the photosensitive drum 21 before charging.

  The exposure apparatus 25 forms an electrostatic latent image corresponding to predetermined image data (for example, image data received by the printer 1 from an external terminal) by irradiating the peripheral surface of the photosensitive drum 21 with laser light. .

The developing device 27 includes a developing roller 27a and first and second stirring rollers 27d and 27e. The developing roller 27a is disposed to face the photosensitive drum 21. The developing roller 27 a is disposed in parallel to the photosensitive drum 21. A gap is provided between the peripheral surface of the developing roller 27 a and the peripheral surface of the photosensitive drum 21. This gap is held constant by an interval holding roller 27b described later. The developing roller 27a and the first and second stirring rollers 27d and 27e are accommodated in the developing housing 27f. A toner container 28 (see FIG. 1) is mounted on the upper surface of the developing housing 27f . The toner is supplied from the toner container 28 into the developing housing 27f . The toner supplied to the developing housing 27 in f, the first and second stirring rollers 27d, is charged with being stirred by 27e. The developing roller 27 a causes the agitated toner to adhere to the peripheral surface thereof and transfer it to the peripheral surface of the photosensitive drum 21. Then, the electrostatic latent image on the peripheral surface of the photosensitive drum 21 is visualized as a toner image by the developing roller 27a.

  The developing roller 27a is rotatably supported by the rotating shaft 27c. The rotation shaft 27c is rotatably supported by the housing 60 via a bearing (not shown). A distance maintaining roller 27b having a larger diameter than the developing roller 27a is supported at both ends of the rotating shaft 27c. Thus, the spacing roller 27b is connected to the developing roller 27a via the rotating shaft 27c. The spacing roller 27b is brought into contact with the peripheral surface of the photosensitive drum 21 by contacting the peripheral surface thereof with the distance between the axes of the photosensitive drum 21 and the developing roller 27a (by extension, the photosensitive drum 21 and the developing roller). 27a) is kept constant.

  The transfer device 29 has a transfer roller 29a to which a transfer bias is applied. The toner image formed on the peripheral surface of the photosensitive drum 21 is transferred to the paper P when the paper P passes between the photosensitive drum 21 and the transfer roller 29a.

The cleaning device 30 is disposed on the opposite side of the photosensitive drum 21 from the developing device 27 side. The cleaning device 30 includes a cleaning blade 31, a cleaning roller 32, a recovery screw 33, and a cleaning case 34. The cleaning roller 32 is in pressure contact with the photosensitive drum 21 at a predetermined pressure, and removes foreign matter adhering to the peripheral surface of the drum 21 by friction polishing. A plate-like toner regulating plate 36 is in contact with the peripheral surface of the cleaning roller 32 . The toner regulating plate 36 is provided to regulate the thickness of the toner layer formed on the peripheral surface of the cleaning roller 32 to a predetermined thickness or less.

The cleaning blade 31 is a rectangular plate extending in the drum axis direction. The cleaning blade 31, when viewed from the drum axial direction, the base end portion (upper end portion) and the distal end portion is fixed to the cleaning case 3 4 (lower part) is disposed so as to contact the circumferential surface of the drum 21. The tip of the cleaning blade 31 is located downstream of the contact surface with the cleaning roller 32 on the peripheral surface of the photosensitive drum 21 in the drum rotation direction. The cleaning blade 31 scrapes off the foreign matter on the peripheral surface of the photosensitive drum 21 and drops it into the cleaning case 34. The foreign matter scraped off from the peripheral surface of the photosensitive drum 21 by the cleaning blade 31 is discharged to the outside of the cleaning device 30 by the recovery screw 33. The discharged residual toner is collected in a collection container (not shown). Here, the foreign matter, residual toner, remaining on the peripheral surface of the transfer roller 29 a photosensitive drum 21 without being transferred to the sheet P by the condensation and the like of the outer添材and paper dust contained in the residual toner included.

  Side seals 35 as seal members are provided at both ends of the cleaning blade 31. Each side seal 35 is made of, for example, urethane foam or felt. Specifically, as shown in FIG. 3, each side seal 35 is formed of a T-shaped member having a seal body 35a, a first fixed piece 35b, and a second fixed piece 35c. The seal body 35a is formed in a rectangular plate shape that extends in the drum axis direction. The seal body 35a is disposed so as to cover both ends of the tip of the cleaning blade 31 in the drum axial direction from the upstream side in the drum rotation direction. The seal body 35 a is in contact with both the cleaning blade 31 and the photosensitive drum 21. The first and second fixed piece portions 35b and 35c are connected to the outer end portion of the seal main body portion 35a in the drum axis direction. The seal body 35a is fixed to the housing 60 via the first and second fixed pieces 35b and 35c. The first fixed piece 35b is in contact with the outer end surface of the cleaning blade 31 in the drum axis direction. Each side seal 35 plays a role in preventing foreign matter scraped by the cleaning blade 31 from leaking from both ends in the drum axial direction.

  By the way, when the photosensitive drum 21 is activated, the tip of the cleaning blade 31 is dragged to the peripheral surface of the drum 21 and bends downstream in the drum rotation direction. For this reason, the foreign matter (for example, the condensate) scraped off by the cleaning blade 31 may pass through between the tip of the cleaning blade 31 and the peripheral surface of the photosensitive drum 21 and leak to the downstream side in the drum rotation direction. is there. When the leaked foreign matter adheres to the charging roller 23a, charging unevenness occurs on the peripheral surface of the photosensitive drum 21, and the image quality of the printed image is deteriorated. In order to avoid this problem, the pre-charging cleaning sheet 24 is provided upstream of the charging roller 23a in the drum rotation direction.

  This pre-charging cleaning sheet 24 is a rectangular sheet extending in the drum axis direction. The pre-charging cleaning sheet 24 is made of, for example, urethane, ester rubber, or foam rubber. The base end side of the pre-charging cleaning sheet 24 is fixed to the charging case 23 c of the charger 23. On the other hand, the leading end side of the pre-charging cleaning sheet 24 is in contact (contact) with the peripheral surface of the photosensitive drum 21 while being bent downstream in the drum rotation direction. Both ends of the pre-charging cleaning sheet 24 in the drum axial direction are located outside the both ends of the charging roller 23a in the drum axial direction. The pre-charging cleaning sheet 24 captures foreign matter that has passed through the cleaning blade 31 (that is, foreign matter that could not be removed by the cleaning blade 31).

  As shown in FIG. 4, the cleaning blade 31, the pre-charging cleaning sheet 24, the charging roller 23a, and the developing roller 27a all extend in the drum axis direction and are arranged in parallel to each other. The central positions of the cleaning blade 31, the pre-charging cleaning sheet 24, the charging roller 23 a, and the developing roller 27 a in the drum axial direction coincide with the central position of the photosensitive drum 21 in the axial direction. Both spacing rollers 27b connected to the developing roller 27a are arranged symmetrically with respect to the center position of the photosensitive drum 21 in the drum axial direction.

In FIG. 4, the length of the charging roller 23a in the drum axis direction is A, the length of the pre-charging cleaning sheet 24 in the drum axis direction is B, and the side of the contact portion of the cleaning blade 31 with the photosensitive drum 21 is the side. portions which are not sealed by the seal 35 (hereinafter, effective as cleaning unit 31a) the drum shaft direction length of is C, the distance between the two space holding roller 27b is D, the drum axes of the side seal 35 E is the distance between the outer ends in the direction.

  In the present embodiment, the relationship of A <B <C <D <E is satisfied. In the conventional example, as shown in FIG. 6, A <C <B <D <E, and in this embodiment, the size relationship between the dimension B and the dimension C is reversed as compared with the conventional example. That is, both ends of the pre-charging cleaning sheet 24 in the drum axial direction are located outside the both ends of the effective scraping portion 31a of the cleaning blade 31 in the drum axial direction in the conventional example, whereas in the present embodiment, The effective scraping portion 31a of the cleaning blade 31 is located inside the both ends in the drum axial direction.

  Therefore, in this embodiment, the foreign matter leaked from the both ends in the drum axial direction of the pre-charging cleaning sheet 24 to the downstream side in the drum rotation direction does not accumulate on the upstream portion in the drum rotation direction of the side seal 35 as in the conventional example. Then, it reaches the effective scraping portion 31a of the cleaning blade 31 and is scraped off by the effective scraping portion 31a (see the thick arrow in FIG. 4). Therefore, it is possible to prevent foreign matters leaking from both ends of the pre-charging cleaning sheet 24 from accumulating on the upstream portion of the side seal 35 in the drum rotation direction. As a result, the accumulated foreign matter is prevented from leaking from the space between the side seal 35 and the peripheral surface of the photosensitive drum 21 to the downstream side in the drum rotation direction and adhering to the peripheral surface of the spacing roller 27b. be able to. Therefore, the axial distance between the photosensitive drum 21 and the developing roller 27a can be kept constant, and the quality of the printed image can be improved.

  Further, in the present embodiment, the spacing roller 27 b is disposed so as to be located inside the outer end of the side seal 35 and outside the inner end of the side seal 35 in the drum axis direction. (C <D <E).

  According to this configuration, foreign matter leaked from the side seal 35 is likely to adhere to the peripheral surface of the spacing roller 27b. However, in the present embodiment, by satisfying the relationship of B <C described above, it is possible to reliably prevent foreign matters from adhering to the spacing roller 27b. And according to this structure, compared with the case where the space | interval holding | maintenance roller 27b is arrange | positioned rather than the side seal 35 in the drum-axis direction outside, the printer 1 whole can be reduced in size.

  Therefore, in the present embodiment, it is possible to prevent foreign matter leaking from both ends of the pre-charging cleaning sheet 24 in the drum axial direction from adhering to the spacing roller 27b while preventing the entire printer 1 from becoming large. it can.

"Example"
Experiments were actually performed with the structure of the above embodiment. The specifications of the printer 1 used for the experiment are as follows.

<Monochrome printer>
Photosensitive drum: A-Si drum φ30mm
Line speed 410mm / s
Development method: Magnetic one-component development Developing roller: Outer diameter φ20mm
Spacing roller: Outer diameter φ20.6mm
Transfer member: Roller with outer diameter of φ20mm
φ8 metal shaft + EPDM foam (foam thickness 6.0mm)
Resistance 6.5logΩ
Charging method: Contact charging roller method Charging roller: Epichlorohydrin rubber φ12mm (shaft φ6mm)
Brush roller: φ10mm 6 denier 180KF / inch2 Hair length 2.5mm

<Cleaning device>
Cleaning blade: Urethane rubber Thickness t = 2.0mm
Cleaning roller: EPDM φ14mm (shaft φ10mm)
Photoreceptor linear speed ratio 1.2 (forward rotation)
Load on photoconductor drum Drive side 15N Driven side 9N
Toner regulating plate: SUS thickness t = 0.05 mm
The amount of biting into the cleaning roller 0.5mm
Pressure contact angle: 12 °
Cleaning sheet before charging: Thermoplastic urethane sheet Thickness t = 0.2mm
1.3mm bite into the photoconductor drum

  In the printer 1 configured as described above, the length of the pre-charging cleaning sheet 24 in the drum axis direction (dimension B) and the length of the effective scraping portion 31a of the cleaning blade 31 in the drum axis direction (dimension C) A printing test was conducted with various changes in size. Then, after the printing test, the presence or absence of foreign matters (condensate of toner external additive and paper powder in this experiment) on the peripheral surface of the spacing roller 27b was examined.

In the printing test, intermittent printing was performed for every 20,000 sheets. In the case of intermittent printing, the operation of starting after stopping the photosensitive drum 21 is repeated. For this reason, every time the photosensitive drum 21 is activated, the tip of the cleaning blade 31 is dragged by the photosensitive drum 21 to bend in the drum rotation direction. At this time, the cleaning blade 3 1 foreign matter deposited on the leading edge is leaked into the downstream side of the direction of drum rotation from between the photosensitive drum 21 and the blade 31, the adhesion of foreign matter into space holding roller 27b mentioned above problem Is likely to occur. In this experiment, the experiment was carried out after intentionally creating an environment in which foreign matter is likely to adhere to the spacing roller 27b.

  FIG. 5 is a table showing the results. “Present” in the table indicates that foreign matter has adhered to the peripheral surface of the spacing roller 27b, and “None” indicates that foreign matter has not adhered. According to this table, in Comparative Examples 1 and 2 having a relationship of C <B and Comparative Example 3 having a relationship of C = B, foreign matter adhered to the peripheral surface of the spacing roller 27b, whereas B In Example 1 and Example 2 having the relationship <C, it can be seen that no foreign matter adhered to the peripheral surface of the spacing roller 27b.

<< Other embodiments >>
In the above embodiment, a gap is provided between the peripheral surface of the developing roller 27a and the peripheral surface of the photosensitive drum 21, but the present invention is not limited to this, and for example, both may be in contact with each other. .

  In the above-described embodiment, the laser printer 1 has been described as an example of the image forming apparatus. However, the image forming apparatus is not limited thereto, and may be another image forming apparatus such as a copier, a scanner device, or a multifunction peripheral. .

  As described above, the present invention is useful for an image forming apparatus including a cleaning member for removing foreign matter on the peripheral surface of a photosensitive drum, and in particular, the distance between the developing roller and the photosensitive drum is set to a predetermined distance. It is useful for an image forming apparatus provided with a distance maintaining roller for holding the image.

1 Printer (image forming device)
21 Photosensitive drum 23a Charging roller 24 Cleaning sheet before charging (second cleaning member)
25 Exposure device 27a Developing roller 27b Spacing roller 27c Rotating shaft 31 Cleaning blade (first cleaning member)
31a Effective scraping part 35 Side seal (seal member)

Claims (2)

A photosensitive drum having a photosensitive layer on the peripheral surface, a charging roller disposed opposite to the photosensitive drum and charging the peripheral surface by contacting the peripheral surface of the photosensitive drum, and charged by the charging roller An exposure device that forms an electrostatic latent image by exposing the peripheral surface of the photosensitive drum,
A developing roller disposed opposite to the photosensitive drum and developing an electrostatic latent image on the circumferential surface of the photosensitive drum; and disposed downstream of the developing roller in the drum rotation direction. A first cleaning member that scrapes off foreign matter on the peripheral surface by contacting the peripheral surface, and disposed downstream of the first cleaning member in the drum rotation direction and upstream of the charging roller in the drum rotation direction. And a second cleaning member that contacts the peripheral surface of the photosensitive drum and captures foreign matter on the peripheral surface, and is connected to the developing roller and rotates in contact with the peripheral surface of the photosensitive drum. a pair of spacing rollers for holding the developing roller and the center distance of the photosensitive drum at a predetermined distance in the drum of the contact portion between the photosensitive drum in the first cleaning member An image forming apparatus comprising a pair of sealing members for sealing opposite end portions, respectively, and
The pair of spacing rollers are disposed on the downstream side of the pair of seal members in the drum rotation direction, and the spacing rollers are more than the outer ends of the pair of sealing members in the drum axial direction. Disposed inside and outside the inner ends of the pair of seal members ,
When a portion of the contact portion of the first cleaning member that is in contact with the photosensitive drum that is not sealed by the seal member is an effective scraping portion,
Both ends in the drum axial direction of the second cleaning member are located 1 mm or more inside both ends of the effective scraping portion in the drum axial direction,
The image forming apparatus, wherein inner ends of the pair of spacing rollers in the drum axial direction are positioned outside by 3 mm or more from both ends of the effective scraping portion in the drum axial direction. The image forming apparatus according to claim 1.
The image forming apparatus, wherein both ends of the second cleaning member in the drum axial direction are located outside of both ends of the charging roller in the drum axial direction .

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