JP4785554B2 - Development device, image forming device - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus, and in particular, scraping that guides the developer by scraping the developer so that the developer supported by the developer carrier does not leak from the inside to the outside in the axial direction of the developer carrier. The present invention relates to an apparatus including a member.

The developing device described in Patent Document 1 includes a magnetic seal member that discharges inward in order to restrict the flow of toner outward from the axial end of the developing roller by magnetic force, and an end of the magnetic seal member in the rotation direction of the developing roller. And a scraping member that scrapes off the toner and guides the toner to the inside from the axial end, and the toner carried by the developing roller leaks outside from the axial end of the developing roller. It prevents that.
On the other hand, a conventional general developing device is provided with a stationary magnet that does not rotate inside the developing roller. In the developing device described in Patent Document 2, as shown in FIG. 1, the magnetic pole S <b> 1 is opposed to the layer thickness regulating member 3 at a position facing the photosensitive drum 2 and in contact with a region where an image is formed on the photosensitive drum 2. The magnetic pole N1 is disposed at a position where
JP 9-218578 A JP 2000-172071 A

In the developing device disclosed in Patent Document 2, the magnetic pole N1 of position pairs toward the magnetic pole S1 and the above layer thickness regulating member 3 at a position opposing to the photosensitive drum 2 at opposite poles, and generates a vertical magnetic field Is. Therefore, when the magnetic flux densities are almost the same, a horizontal magnetic field is generated in which a magnetic flux in the horizontal direction (tangential direction of the developing roller) exists between the two magnetic poles.
Here, as shown in FIG. 2A, the vertical magnetic field is a magnetic field directed toward the center of the developing roller 1. As shown in FIG. 2 (b), the horizontal magnetic field is a magnetic field directed toward the outer peripheral tangential direction of the developing roller 1. Magnetic field lines are generated around the vertical magnetic field to fix the toner on the surface of the developing roller 1, and magnetic field lines are generated around the horizontal magnetic field in the circumferential direction of the developing roller 1. Therefore, the toner on the developing roller 1 is likely to be scattered around the horizontal magnetic field. If the toner is sealed by using the scattering force of the toner by such a horizontal magnetic field, a high sealing effect is expected.
Therefore, a magnetic seal member and a scraping member as described in Patent Document 1 are provided in the developing device as described in Patent Document 2 where such a magnetic field is formed, and a position near the horizontal magnetic field, particularly where the horizontal magnetic force is strongest. When the scraping member is provided, the lump of toner scraped by the scraping member is scattered to the area of the developing roller 1 for supplying toner to the image forming area of the photosensitive drum 2 by the action of a horizontal magnetic field. It was found that the toner adhered to the toner layer made uniform by the layer thickness regulating member 3. As a result, the toner layer is thickened only at the portion where the toner lump is attached, and when the image is formed on the photosensitive drum 2, there is a problem that a black spot is formed and the formed image is adversely affected.
In the present invention, the toner scraped off by the scraping member is prevented from scattering to the area of the developing roller that supplies the toner to the image forming area of the photosensitive drum, thereby improving the image quality. An apparatus and an image forming apparatus including the apparatus can be provided.

As described above, in the conventional developing device for an image forming apparatus, the layer thickness regulation that regulates the layer thickness of the developer carrying member on the surface and the developer carried on the developer carrying member substantially uniformly. A member, a magnetic seal member for discharging the developer carried from the axial end by the magnetic force so that the developer carried by the developer carrying member does not leak outside from the axial end of the developer carrying member, and the magnetic A scraping member for removing the developer adhering to the end portion in the axial direction of the developer carrying member by the magnetic force of the seal member. In addition, the developer carrying member has a first magnetic pole (hereinafter referred to as a layer regulating electrode) at a position facing the layer thickness regulating member and an image developed by the developer carried by the developer carrying member. Has a second magnetic pole (hereinafter referred to as a developing pole) at a position facing the image bearing member. Therefore, when a scraping member is provided in the vicinity of the horizontal magnetic field, particularly in the position where the horizontal magnetic force is the strongest, the lump of developer scraped off by the scraping member forms an image on the image carrier by the action of the horizontal magnetic field. The developer is scattered to the region of the developer carrier that supplies the developer to the region. The scattered developer adheres to the developer layer made uniform by the layer thickness regulating member, so that the developer layer becomes thicker only at the part where the developer lump is adhered, and an image is formed on the image carrier. In this case, there is a problem that black spots are generated and the formed image is adversely affected.
In order to solve this problem, it is necessary to prevent the developer lump scraped off by the scraping member from scattering to the area of the developer carrier that supplies the developer to the image forming area of the image carrier. Don't be. In order to achieve this function, it is necessary to provide the scraping member that generates a lump of developer as described above at a position that is removed from the “center of the horizontal magnetic field” where the force causing the developer scattering is strongest. Most effective.
Therefore, in the present invention, the scraping member is disposed between the position where the layer thickness regulating member is provided and the position where the developer carrier and the image carrier are in contact with each other, and It is provided at a position excluding the position where the horizontal magnetic force generated in the tangential direction of the developer carrier by the developing pole is the strongest.
In particular, the scraping member is provided on the upstream side in the rotation direction of the developer carrier from the position where the horizontal magnetic force generated in the tangential direction of the developer carrier by the layer regulating electrode and the development electrode is the strongest. It is better to configure.
This is because when the scraping member is provided at a position where the horizontal magnetic force is strongest, the developer scraped off by the scraping member as compared with the case where the scraping member is provided at a position other than the position where the horizontal magnetic force is strongest. For the lump of splatters is scattered farther. That is, the developer lump is scattered to the region of the developer carrier that supplies the developer to the image forming region of the image carrier.
As described above, when the scraping member is provided on the upstream side in the rotation direction of the developer carrier from the position where the horizontal magnetic force is strongest, the developer scraped by the scraping member is allowed to form an image on the image carrier. It is possible to prevent the developer from being scattered to the region of the developer carrier that supplies the developer to the region.
Specifically, in particular, a portion of the scraping member that guides the developer scraped by the scraping member from the outside in the axial direction to the inside of the developer carrying member in the axial direction of the developer carrying member. The distance in the same direction on the outer peripheral surface of the developer carrier to the position where the horizontal magnetic force generated in the tangential direction of the developer carrier by the end, the layer regulating electrode, and the developer pole is the strongest. A distance in the same direction on the outer circumferential surface of the developer carrier between a position facing the layer thickness regulating member on the outer circumferential surface of the carrier and a position facing the image carrier on the outer circumferential surface of the developer carrier. It preferably corresponds to approximately 18.0 percent.
Further, it is conceivable that the scraping member is an elastic member and has substantially the same curvature as the developer carrying member.
By using the scraping member as an elastic member, even if the scraping member rubs the developer carrying member when the developer carrying member rotates, the surface thereof is not damaged.
Further, since the scraping member has substantially the same curvature as the developer carrying member, the surface of the scraping member and the surface of the developer carrying member are in close contact with each other without any gap, so that the scraping member adheres to the developer carrying member. The developed developer can be scraped off without flowing from the gap.
On the other hand, it is conceivable to have a support member that is fixed to the layer thickness regulating member and supports the scraping member in contact with the surface of the developer carrying member.
In order to fix the scraping member, a support member is required. However, since the support member is fixed to the layer thickness regulating member by the above-described configuration, a new member for fixing the support member is used. There is no need to provide a member and it is inexpensive.
It is conceivable that a developer accommodating portion for accommodating the developer supplied to the developer carrying member is provided, and the support member is the developer accommodating portion.
Since the support member is the developer accommodating portion, it is not necessary to provide a new support member, so that it can be made cheaper than a case where a new support member is provided.
Further, an image forming apparatus provided with the developing device as described above can be considered.
As a result, the developer scraped off by the scraping member can be prevented from being scattered in the region of the developer carrier that supplies the developer to the image forming region of the image carrier. Therefore, it is possible to prevent the quality of the formed image from being deteriorated due to scattering of the developer lump scraped off by the scraping member.

  According to the present invention, the developing device capable of preventing the lump of toner scraped off by the scraping member from being scattered in the region of the developing roller that supplies toner to the image forming region of the photosensitive drum, and an image including the developing device. A forming apparatus can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a schematic diagram showing a magnetic field formed on the developing roller 1 of a conventional general developing device, FIG. 2 is a schematic diagram showing toner movement in a vertical magnetic field and a horizontal magnetic field, and FIG. FIG. 4 is a cross-sectional view of the image forming apparatus X including the developing device Y according to the embodiment. FIG. 4 illustrates the scraping member 47 and the horizontal magnetic force provided in the developing roller 39 of the developing device Y according to the embodiment of the invention. FIG. 5 is a schematic diagram showing the relationship with the strongest position. FIG. 5 is a schematic diagram showing the relationship between the scraping member 47 provided on the developing roller 39 and the position with the strongest horizontal magnetic force, as viewed from the direction P in FIG. FIG. 7 is a schematic diagram showing a magnetic force distribution on the surface of the developing roller 39 of the developing device Y according to the embodiment of the present invention, and FIG. 7 is an enlarged schematic diagram of the scraping member 47.
In FIG. 5, the support member 48 is omitted for explanation.

First, a schematic configuration of the image forming apparatus X provided with the developing device Y according to the embodiment of the present invention will be briefly described with reference to the schematic diagram of FIG.
As shown in FIG. 3, the image forming apparatus X is roughly divided into a sheet feeding unit K, an image forming unit G, and a fixing unit T.
The paper feed unit K is provided below the main body of the image forming apparatus X, and includes a paper feed cassette 30 that stores a plurality of recording papers of a predetermined size, and a supply of the recording paper stored in the paper feed cassette. A paper feed roller 32 for feeding paper, a separation roller 33 (separation rollers 33-1 and 33-2) for separating the recording paper fed by the paper feed roller 32, and the paper feed cassette 30 are not above. A manual feed tray 31 that feeds regular recording paper, a manual feed roller 34 that feeds the recording paper placed on the manual feed tray 31, the separation roller 33, and the manual feed roller 34. An intermediate conveyance roller 35 that conveys the conveyed recording paper, a registration roller 36 (registration rollers 36-1 and 36-2), and a paper feed motor (not shown) that rotationally drives each of the rollers.
The registration roller 36 is a roller that conveys the recording paper so that the leading end portion (image formation start portion) of a toner image formed on the surface of the photosensitive drum 37 described later is synchronized with the leading end portion of the recording paper.

  The image forming unit G irradiates a photosensitive drum 37 (an example of an image carrier) that carries an image, a charging unit that charges the surface of the photosensitive drum 37, and a laser beam on the photosensitive drum 37. A laser scanner unit L that forms an electrostatic latent image; a developing device Y that forms a toner image on the surface of the photosensitive drum 37 by attaching toner contained in a developer to the electrostatic latent image; A cleaning unit for cleaning the photosensitive drum 37, a charge eliminating unit for removing a potential remaining on the photosensitive drum 37 after transfer, and development described later provided in the photosensitive drum 37 and the developing device Y. A drum motor (not shown) that rotationally drives the roller 39, the supply roller 40, and the stirring roller 41 is configured.

Next, a schematic configuration of the developing device Y according to the embodiment of the present invention provided in the image forming unit G will be described.
The developing device Y includes a developing roller 39 (an example of a developer carrying member) that supports the developer on the surface, a supply roller 40 that stirs the developer and supplies the developer to the developing roller 39, and stirs the developer. A stirring roller 41 that supplies developer to the supply roller 40, a developer supply port 42 that is an inlet for supplying developer, a developer storage portion 43 that stores the developer, and the developer storage portion 43 A transport roller 44 for transporting the contained toner to the developer supply port, a layer thickness regulating member 45 (see FIG. 4) for regulating the layer thickness of the toner carried on the developing roller 39 substantially uniformly, and the developing A magnetic seal member 46 (see FIG. 4) that discharges toner from the end in the rotation axis direction by a magnetic force so that the toner carried by the roller 39 does not leak outside from the end in the rotation axis direction of the developing roller 39; sticker A scraping member 47 (see FIG. 4) for removing the toner adhering to the end of the developing roller 39 in the rotation axis direction by the magnetic force of the material 46, and a support member 48 (see FIG. 4) for supporting the scraping member 47. ) And a housing (not shown) for storing or supporting them.

As shown in FIGS. 4 and 6, the developing roller 39 includes a fixed magnet 39a and a non-magnetic cylindrical developing sleeve 39b rotatably provided outside the fixed magnet 39a. .
The fixed magnet 39a is fixedly supported by the housing (not shown) so as not to rotate. As shown in FIG. 4, the outer periphery of the developing sleeve 39b and the center of the fixed magnet 39a are point O.
The fixed magnet 39a has a magnetic pole K1 (hereinafter referred to as a line J connecting the center O and the axis A of the photosensitive drum 37 in FIG. 4), that is, a position where the developing sleeve 39b faces the photosensitive drum 37. , A development pole K1 and an example of a second magnetic pole). The developing pole K1 is, for example, an N pole, and a magnetic pole that generates a magnetic flux density of 81.5 mT (Tesla) + − 5 mT.
The fixed magnet 39a further has a magnetic pole K2 (hereinafter referred to as a layer regulating pole K2, which is an example of a first magnetic pole) in the vicinity of the position facing the layer thickness regulating member 45. Specifically, a central angle (∠k1Ok2 formed by Ok1 and Ok2 in FIG. 4) with respect to the center of the fixed magnet 39a from the center k1 of the developing pole K1 to the center k2 of the layer regulating pole K2 is: The layer regulation pole K2 is provided at a position of 139 °.
In FIG. 4, D is an end portion of the layer thickness regulating member 45 facing the developing roller 39. If a line segment passing through the center O and the end portion D of the layer thickness regulating member 45 is OD, ∠DOk2 is set to 10 °. The layer regulating pole K2 is, for example, an S pole, and a magnetic pole that generates a magnetic flux density of 84.5 mT (Tesla) + − 5 mT. When the magnetic toner carried on the developing sleeve 39b approaches the layer regulation pole K2, it is lifted by the magnetic force generated by the layer regulation pole K2.
The developing sleeve 39b rotates counterclockwise (in the direction of arrow P1 in FIG. 4) along the outer periphery of the fixed magnet 39a.
The layer thickness regulating member 45 regulates (compresses) the toner lifted by the magnetic force generated by the layer regulating pole K2 in addition to the role of making the layer thickness of the toner carried on the developing roller 39 substantially uniform. In this way, the toner is charged by friction. By charging the toner in this way, the toner can easily transfer to the electrostatic latent image written on the photosensitive drum 37 during development.
As shown in FIGS. 4 and 5, the magnetic seal member 46 is a magnet provided at both ends of the developing sleeve 39b in the rotation axis direction with a constant gap from the outer peripheral surface thereof. A magnetic field is formed between the magnet 39a and the toner that flows into the gap by the magnetic force repelling the fixed magnet 39a is electromagnetically removed. As a result, the toner carried on the developing sleeve 39b is prevented from leaking from the inner side to the outer side in the rotation axis direction of the developing sleeve 39b. The magnetic seal member 46 is formed downstream of the layer thickness regulating member 45 in the rotation direction of the developing sleeve 39b (the direction of the arrow P1 in FIGS. 4 and 5).
The scraping member 47 includes an end portion of the magnetic seal member 46 in the rotation direction of the developing sleeve 39b (in the direction of arrow P1 in FIG. 5), and a rotation axis direction of the developing sleeve 39b (in the directions of arrows P3 and P4 in FIG. 5). Provided at both ends, for example, is made of an elastic member such as urethane or synthetic rubber. That is, the scraping member 47 is provided downstream of the layer thickness regulating member 45 in the rotation direction of the developing sleeve 39b.
FIG. 7A is a schematic view of the scraping member 47 viewed from the side (in the direction of arrow P3 in FIG. 5), and FIG. 7B is a top view of the scraping member 47 (in the direction of arrow P in FIG. 4). FIG. 7C is a perspective view of the scraping member 47. As shown in FIG. 7C, the scraping member 47 has a bottom 47-H1 of the upstream slope 47-M1 in the rotation direction of the developing sleeve 39b from the rotation axis direction end portion to the rotation axis direction center portion. It is formed to be inclined. That is, as shown in FIG. 5, of the points 47-T1 and 47-T2 which are the ends of the base 47-H1, the point 47− located outside in the rotation axis direction (the directions of arrows P3 and P4 in FIG. 5). T2 is formed to be upstream of the point 47-T1 on the inner side in the rotation direction of the developing sleeve 39b (in the direction of arrow P1 in FIG. 5). The inclined surface 47-M1 of the scraping member 47 scrapes off toner that is about to leak from the inner side to the outer side in the rotation axis direction of the developing sleeve 39b. Then, the toner lump generated by being scraped off by the slope 47-M1 of the scraping member 47 is guided to the inside of the developing sleeve 39b in the rotation axis direction by the slope of the bottom 47-H1 of the slope 47-M1. Is done. The flow of toner is indicated by arrows P5 and P6 in FIG. As a result, the toner carried on the developing sleeve 39b is prevented from leaking from the inner side to the outer side in the rotation axis direction of the developing sleeve 39b.
Of the surfaces constituting the scraping member 47, a surface 47-M2 (see FIG. 7C) that contacts the developing sleeve 39b has substantially the same curvature as the surface of the developing sleeve 39b. With such a configuration, the surface of the scraping member 47 and the surface of the developing sleeve 39b are in close contact with each other without any gap, so that the toner adhering to the developing sleeve 39b can be scraped off without flowing from the gap.
Details of the position at which the scraping member 47 is provided on the developing sleeve 39b will be described later.
The support member 48 is a member that supports the scraping member 47 and is fixed to the layer thickness regulating member 45. It is also conceivable that the support member 48 is a part of a housing that accommodates the developer accommodating portion 43. With such a configuration, since the support member 48 is fixed to the layer thickness regulating member 45 and the casing, it is not necessary to provide a new member for fixing the support member 48, and it is inexpensive. is there.

Next, an image forming process executed by the image forming apparatus X will be briefly described focusing on functions in the developing device Y.
When the user performs an image output operation from an information processing apparatus such as a personal computer that is communicably connected to the image forming apparatus X, the recording paper stored in the paper feed cassette 30 is transferred to the paper feed. The paper is fed by the roller 32 and separated one by one by the separation roller 33. The recording paper separated by the separation roller 33 is conveyed to the registration roller 36 by the intermediate conveyance roller 35. The recording sheet conveyed by the intermediate conveyance roller 35 is further conveyed to the image formation start position by the registration roller 36.
On the other hand, when an image is formed on an irregular recording paper or the like, paper is fed by the manual feed tray 31. When a predetermined input operation is performed by the user from the operation input unit, the recording paper placed on the manual paper feed tray 31 is fed by the manual paper feed roller 34 and is fed by the intermediate transport roller 35. It is conveyed to the registration roller 36. The recording sheet conveyed by the intermediate conveyance roller 35 is further conveyed to the image formation start position by the registration roller 36.

When the user performs an image output operation on the information processing apparatus, an image information signal (digital image data) is transmitted from the information processing apparatus to the image forming apparatus X. The transmitted image information signal is subjected to predetermined image processing in the image forming apparatus X and input to the laser scanner unit L. Thereafter, a laser beam according to the image data after image processing is emitted from the laser scanner unit L to the surface of the photosensitive drum 37.
The toner transported from the developer accommodating portion 43 by the transport roller 44 through the developer replenishing port 42 in the developing device Y is driven by the drum motor 45 to rotate the supply roller. 40. The supply roller 40 is rotationally driven by a drum motor (not shown) to supply toner to the developing sleeve 39b of the developing roller 39.
Subsequently, the developing sleeve 39b is rotated counterclockwise (in the direction of arrow P1 in FIG. 4) by the drum motor, and the toner supplied onto the developing sleeve 39b by the supply roller 40 is carried by the developing sleeve 39b. Is done. Subsequently, the developing sleeve 39b is rotated by the drum motor, and the toner carried by the developing sleeve 39b is lifted by the magnetic force of the layer regulating pole K2, and then a substantially uniform toner layer is formed by the layer thickness regulating member 45. It is formed.
Here, the magnetic seal member 46 and the scraping member 47 are provided at both ends of the developing sleeve 39b in the rotation axis direction, so that the toner carried by the developing sleeve 39b is moved inward in the rotation axis direction of the developing sleeve 39b. Leakage from the outside is prevented.
Subsequently, the developing sleeve 39b is rotated by the drum motor, and a thin layer of toner formed on the surface of the developing sleeve 39b comes into contact with the surface of the photosensitive drum 37. The photosensitive drum 37 is rotated clockwise (in the direction of arrow P2 in FIG. 4) by the drum motor in synchronization with the rotation of the developing sleeve 39b. As a result, the charged toner adheres to the electrostatic latent image on the surface of the photosensitive drum 37 to form a toner image. Here, an area where an image is formed on the photosensitive drum 37 is referred to as an image forming area. The photosensitive drum 37 is continuously rotated by the drum motor, and the toner image is transferred onto the recording paper conveyed by the registration roller 36 by a transfer roller pressed against the photosensitive drum 37. A cleaning unit is disposed downstream of the transfer roller in the rotation direction of the photosensitive drum 37, and toner and other deposits remaining on the surface of the photosensitive drum 37 are removed. A neutralization unit is provided on the downstream side of the cleaning unit in the rotation direction of the photosensitive drum 37, and potential remaining on the photosensitive drum 37 is removed. The toner image transferred to the recording paper is heated by the fixing roller of the fixing unit T and fixed on the recording paper.
Hereinafter, the developing sleeve 39b area that supplies toner to the image forming area of the photosensitive drum 37 is referred to as a developing area.

By the way, a vertical magnetic field is formed by the developing pole K1 formed by the fixed magnet 39a of the developing roller 39 and the layer regulating pole K2. The perpendicular magnetic force distribution formed by the development pole K1 and the layer regulation pole K2 is shown in FIG. FIG. 6 shows a horizontal magnetic force distribution generated by the vertical magnetic force of the developing pole K1 and the layer regulating pole K2.
As already described, it is known that the toner on the developing roller is likely to be scattered around the horizontal magnetic field.
As described above, the magnetic seal member 46 and the scraping member 47 are provided at both ends in the rotation axis direction of the developing sleeve 39b, so that the toner carried by the developing sleeve 39b can rotate the developing sleeve 39b. Although it prevents leakage from the inner side to the outer side in the axial direction, when the scraping member 47 is provided in a horizontal magnetic field, a lump of toner scraped by the scraping member 47 is scattered to the developing area. Thus, it adheres to the toner layer made uniform by the layer thickness regulating member 45. As a result, the toner layer is thickened only in the portion where the toner lump is attached, and a black spot is formed when an image is formed on the photosensitive drum 37, and the quality of the formed image is lowered. For this reason, in the present embodiment, as described below, the scraping member 47 is provided at a position where the lump of toner scraped by the scraping member 47 is unlikely to scatter in the development area.

Here, as shown in FIG. 5, at the end of the developing sleeve 39b in the rotational axis direction (the direction of arrow P4 in FIG. 5), the position in contact with the photosensitive drum 37 is A1, and the position with the highest horizontal magnetic force is B1, The development facing the end portion D of the layer thickness regulating member 45 at a position intersecting with a line passing through the point 47-T1 constituting the inclined surface of the scraping member 47 and parallel to the rotation axis of the developing sleeve 39b. A position intersecting with a line passing through a position on the sleeve 39b and parallel to the rotation axis is D1, and a position where the perpendicular magnetic force generated by the layer regulating pole K2 is the strongest is E1. Points corresponding to A1, B1, C1, D1, and E1 at the opposite end of the developing sleeve 39b are referred to as A2, B2, C2, D2, and E2.
Incidentally, the side 47-M2 (see FIG. 7C) that contacts the developing sleeve 39b of the scraping member 47, and the side that plays an important role in guiding the toner is the side 47-H1. . Of the two points forming the side 47-H1, the position of the point 47-T1 downstream in the rotation direction of the developing sleeve 39b (the direction of the arrow P1 in FIG. 7) is important. This is because the point 47-T1 forms the side inclined with respect to the rotation direction of the developing sleeve 39b by the point 47-T2 (see FIG. 7C) and the point 47-T1. This is because the lump of toner scraped off by the removing member 47 is guided to the inside of the developing sleeve 39b in the axial direction by the inclination and flows into the vicinity of the developing region.
As an example, the distance from the position where the perpendicular magnetic force generated by the developing pole K1 is the strongest (line segment A1A2 in FIG. 5) to the position where the vertical magnetic force generated by the layer regulating pole K2 is the strongest (line segment E1E2 in FIG. 5) is Assuming approximately 24.24 mm, a line (in FIG. 5) parallel to the rotational axis of the developing sleeve 39b from the position where the horizontal magnetic force is the strongest (line B1B2 in FIG. 5) passes through the point 47-T1 of the scraping member 47. Experiments have shown that if the distance to the line segment C1C2) is at least approximately 4.38 mm away, the lump of toner scraped by the scraping member 47 will not scatter to the development area due to the horizontal magnetic force. .
Therefore, the distance from the position where the perpendicular magnetic force generated by the developing pole K1 is the strongest (line segment A1A2 in FIG. 5) to the position where the vertical magnetic force generated by the layer regulating pole K2 is the strongest (line segment E1E2 in FIG. 5) is 100. Assuming that it is a percentage, the scraping member 47 may be installed so that the point 47-T1 is located approximately 18.0% or more away from the position where the horizontal magnetic force is the strongest (line B1B2 in FIG. 5). At this position, it is possible to prevent the toner lump scraped off by the scraping member 47 from being scattered to the developing area by the horizontal magnetic force.
The scraping member 47 is provided on the upstream side of the rotation direction of the developing sleeve 39b (the direction of the arrow P1 in FIG. 4) from the position where the horizontal magnetic force is the strongest (see FIG. 4). Experiments have shown that toner lump is less likely to scatter than provided downstream (in the direction of arrow P1 in FIG. 4).
In combination with what has already been described, the position at which the scraping member 47 is provided is downstream of the layer thickness regulating member 45 in the rotation direction of the developing sleeve 39b (in the direction of arrow P1 in FIG. 4) and the horizontal direction. The upstream side in the rotation direction of the developing sleeve 39b (in the direction of arrow P1 in FIG. 4) is more appropriate than the position where the magnetic force is strongest.

  With the configuration described above, it is possible to prevent the lump of toner scraped off by the scraping member 47 from being scattered in the developing area of the developing roller 39 that supplies toner to the image forming area of the photosensitive drum 37. . Therefore, the deterioration of the image quality caused by the scattering of the toner lump scraped off by the scraping member 47 is prevented.

The schematic diagram which shows the magnetic field formed on the developing roller 1 of the conventional general developing device. FIG. 4 is a schematic diagram illustrating toner movement in a vertical magnetic field and a horizontal magnetic field. 1 is a cross-sectional view of an image forming apparatus X including a developing device Y according to an embodiment of the present invention. The schematic diagram which shows the relationship between the scraping member 47 with which the developing roller 39 of the image development apparatus Y which concerns on embodiment of this invention was equipped, and a horizontal magnetic force is the strongest. FIG. 5 is a schematic diagram showing a relationship between a scraping member 47 provided on the developing roller 39 and a position where the horizontal magnetic force is strongest, as viewed from the P direction in FIG. 4. FIG. 6 is a schematic diagram showing a magnetic force distribution on the surface of the developing roller 39 of the developing device Y according to the embodiment of the present invention. The enlarged schematic diagram of the scraping member 47. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,39 ... Developing roller 2,37 ... Photoconductor drum 3,45 ... Layer thickness control member 46 ... Magnetic seal member 47 ... Scraping member 48 ... Support member

Claims (6)

A layer thickness regulation that regulates the layer thickness of the developer carrying member on the surface and the developer carried on the developer carrying member in a non-contact manner to regulate the layer thickness of the developer substantially uniformly. a member, and the magnetic seal member developer carried by the developer carrying member is expelled inward than the axial end portion by a magnetic force so as not to leak to the outside from the axial end portion of the developer carrying member, the magnetic A scraping member for removing the developer attached to the axial end of the developer carrier by the magnetic force of the seal member , and a developing device comprising :
The developer carrying member, a first magnetic pole and the image carrier facing carrying the image to be developed with a developer carried by the developer carrying member which is provided at a position opposed to the layer thickness regulating member becomes a second magnetic pole provided at a position,
The scraping member is a between a position above layer thickness regulating member is provided position and the developer carrying member and the said image bearing member is in contact, and the first magnetic pole and the second pole Ri Na provided at a position except for the strongest position horizontal magnetic force generated in the tangential direction of the developer carrying member by,
The developing device according to claim 1, wherein the scraping member is formed of an elastic member, and a surface of the scraping member in contact with the developer carrying member has substantially the same curvature as the surface of the developer carrying member . The scraping member is provided on the upstream side in the rotational direction of the developer carrier from the strongest position horizontal magnetic force generated by the aforementioned first pole and the second magnetic pole in the tangential direction of the developer carrying member The developing device according to claim 1. The surface of the scraping member that faces the layer thickness regulating member is an inclined surface that slopes away from the layer thickness regulating member as it goes from the axial end of the developer carrier to the axial center. The developing device according to claim 1 or 2 . 4. The developing device according to claim 1, further comprising a support member fixed to the layer thickness regulating member and supporting the scraping member in contact with the surface of the developer carrying member . The developing device according to claim 4 , further comprising a developer accommodating portion that accommodates the developer supplied to the developer carrying member, wherein the support member is the developer accommodating portion .   An image forming apparatus comprising the developing device according to claim 1.

Images