JP4842193B2 - Development device - Google Patents

Description

  The present invention relates to a developing device applied to an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  Conventionally, a developing device as described in Patent Document 1 is known. This developing device is applied to an image forming apparatus such as a copying machine or a printer, and has one component on the surface of an image carrier (photosensitive drum in Patent Document 1) incorporated in the main body of the image forming apparatus. System developer (that is, a developer that does not include a carrier and is formed only of toner having a magnetic material) and forms a toner image along an electrostatic latent image on the surface of the image carrier It is.

  Such a developing device has a box shape and has an opening on one side surface that faces the surface of the image carrier, and is loaded with a developer, is housed in the housing, and contains the developer. An agitation roller that circulates and conveys within the housing while stirring, and a developing roller that supplies the developer to the surface of the image carrier through the opening while being conveyed by the agitation roller.

  The opening is provided with a blade that extends over substantially the entire length of the developing roller, the tip edge of which faces the peripheral surface of the developing roller. The developer supplied to the image carrier by the rotation of the developing roller passes through a gap between the blade and the peripheral surface of the developing roller and is cut out by being regulated to a predetermined layer thickness. To be supplied to the image carrier.

The blade is provided with a magnet on the surface opposite to the surface on the image carrier side, and a thin edge portion is formed on an edge portion of the blade facing the peripheral surface of the developing roller. On the other hand, a non-rotating magnet having a reverse polarity is also provided in the developing roller. By doing so, the developer carried on the circumferential surface of the roller by the magnetic force of the developing roller rotating about the axis is placed between the thin edge portion where the magnetic flux is concentrated and the circumferential surface of the developing roller. Induced by the formed strong magnetic field, a thin layer of toner is formed and supplied onto the image carrier, and a toner image is appropriately formed on the image carrier.
JP 2003-167426 A

  By the way, the developer circulated and transported in the casing is charged by friction between the blade and the peripheral surface of the developing roller in the vicinity thereof when transported along the blade, and this charge amount increases as it goes downstream. To go.

  On the other hand, when the magnetic force of the magnet is constant, as the developer moves downstream along the blade in the direction of circulating the developer, the constant magnetic force is increased by the developer having a charge amount that increases. It works strongly. As a result, the developer carried on the peripheral surface of the developing roller and fed toward the image carrier is not uniform between the upstream side and the downstream side in the developer transport direction. If the developer is not uniform, the toner image formed on the image carrier due to this becomes a non-uniform state with density, thereby forming an appropriate toner image on the image carrier. There arises a problem that it cannot be obtained.

  The present invention has been made to solve the conventional problems, and the developer supplied from the developing roller to the image carrier can be made uniform in the longitudinal direction of the developing roller. It is an object of the present invention to provide a developing device capable of forming an appropriate toner image without shading on the body.

  According to a first aspect of the present invention, there is provided a developing roller for supplying toner to the surface of a predetermined image carrier while rotating about an axis in a predetermined housing, and a non-rotating roller side magnet built in the developing roller. And a blade having a magnetic force that regulates the layer thickness of the toner formed on the peripheral surface of the developing roller, and the magnetic force is upstream along the toner conveyance direction in the axial direction on the developing roller. It is set so that it may fall sequentially toward the downstream side from the side.

  According to a second aspect of the present invention, there is provided a developing roller for supplying toner to the surface of a predetermined image carrier while rotating around an axis in a predetermined housing, and a non-rotating roller side magnet built in the developing roller. A blade that regulates the layer thickness of the toner formed on the peripheral surface of the developing roller; and a blade-side magnet attached to the blade over substantially the entire length in the longitudinal direction. The magnetic force is set so as to sequentially decrease from the upstream side toward the downstream side along the toner conveyance direction in the axial direction on the developing roller.

  According to the first and second aspects of the present invention, the toner held in the peripheral surface of the developing roller rotating around the axial center is regulated by the blade to a predetermined layer thickness. When the image bearing member is in a uniform state by the interaction between the magnetic force held by the blade itself or the magnetic force of the blade-side magnet attached to the blade and the magnetic force of the non-rotating developing roller-side magnet built in the developing roller. Supplied towards.

  The magnetic force on the blade side is set so as to decrease sequentially from the upstream side toward the downstream side along the toner conveyance direction in the axial direction on the developing roller. Even if the friction increases from the upstream side toward the downstream side, the influence of the magnetic force applied to the toner is reduced, thereby preventing an increase in stress due to the magnetic force of the toner.

  Further, the supply of toner from the developing roller to the image carrier becomes uniform with no difference in the axial direction of the developing roller, and as a result, the toner image on the image carrier has good image quality.

  The invention according to claim 3 is the invention according to claim 2, wherein the blade side magnet is formed by a plurality of unit magnets arranged in series in the longitudinal direction of the blade. It is.

  According to this configuration, since a plurality of unit magnets having different magnetic forces are employed as the blade-side magnet, for example, by using a commercially available magnet, the manufacturing cost of the blade-side magnet can be reduced.

  According to the developing device of the present invention, the magnetic force on the blade side is set so as to sequentially decrease from the upstream side to the downstream side along the toner conveyance direction in the axial direction on the developing roller. Even if the charge amount of the toner increases from the upstream side to the downstream side due to friction during conveyance, the influence of the magnetic force applied to the toner is reduced, thereby suppressing the increase in stress due to the magnetic force of the toner. Can be prevented.

  Further, the supply of toner supplied from the developing roller to the image carrier becomes uniform with no difference in the axial direction of the developing roller, and as a result, the image quality of the toner image on the image carrier can be improved. it can.

  FIG. 1 is a cross-sectional view illustrating an embodiment of the internal structure of a printer to which a developing device according to the present invention is applied. As shown in FIG. 1, a printer (image forming apparatus) 10 includes a sheet storage unit 12 that stores sheets P to be subjected to a printing process, and one sheet fed from a sheet bundle P1 stored in the sheet storage unit 12. The apparatus main body 11 includes an image forming unit 13 that performs image transfer processing on the paper P and a fixing unit 14 that performs fixing processing on the paper P on which transfer processing has been performed by the image forming unit 13. In addition, a paper discharge unit 15 for discharging the paper P subjected to the fixing process by the fixing unit 14 is provided on the top of the apparatus main body 11.

  A predetermined number (one in this embodiment) of paper cassettes 121 is provided in the paper storage unit 12 so as to be detachable from the apparatus main body 11. A pickup roller 122 is provided at the upstream end (right side in FIG. 1) of the paper cassette 121 to feed out the paper P one by one from the paper bundle P1. The paper P fed out of the paper cassette 121 by driving the pickup roller 122 is supplied to the image forming unit 13 through the paper feed conveyance path 123 and the registration roller pair 124 provided at the downstream end of the paper feed conveyance path 123. Paper.

  The image forming section 13 performs a transfer process on the paper P after performing a predetermined image forming process based on image information transmitted from a computer or the like. The image forming unit 13 is arranged so as to be along a peripheral surface of a photosensitive drum (image carrier) 131 provided rotatably around a drum shaft 131a extending in the front-rear direction (a direction orthogonal to the paper surface of FIG. 1). A charging roller 132, an exposure device 134, a developing device 20, a transfer roller 133, and a cleaning device 135 are arranged in a clockwise direction from a position immediately above the photosensitive drum 131.

  The photosensitive drum 131 is for forming a toner image along the electrostatic latent image after forming the electrostatic latent image on the peripheral surface. The photosensitive drum 131 has a smooth and tough amorphous silicon layer laminated on its peripheral surface, and is suitable for forming an electrostatic latent image and a toner image on the peripheral surface.

  The photosensitive drum 131 is coaxially and integrally supported by a drum shaft 131a extending in the front-rear direction (a direction orthogonal to the paper surface of FIG. 1) at a substantially central portion of the apparatus main body 11, and is driven by a driving means (not shown). The drum shaft 131a rotates integrally with the drum shaft 131a by the drive rotation of the drum shaft 131a toward the clockwise direction.

  The charging roller 132 forms a uniform charge on the peripheral surface of the photosensitive drum 131 rotating clockwise around the drum shaft 131 a, and the peripheral surface abuts on the peripheral surface of the photosensitive drum 131. While being rotated, the photosensitive drum 131 is charged. Instead of the charging roller 132, a corona discharge type that applies a charge to the peripheral surface of the photosensitive drum 131 by corona discharge from a wire may be employed.

  The exposure device 134 irradiates the peripheral surface of the rotating photosensitive drum 131 with laser light based on image data transmitted from an external device such as a computer. An electrostatic latent image is formed on the peripheral surface of the photoconductive drum 131 by erasing the electric charge of the portion irradiated with the laser beam.

  The developing device 20 attaches the toner T to a portion where an electrostatic latent image is formed on the peripheral surface by supplying toner T (depicted in FIG. 2 as a dotted line) as a developer to the peripheral surface of the photosensitive drum 131. As a result, a toner image is formed on the peripheral surface of the photosensitive drum 131. In this embodiment, a so-called magnetic one-component system composed of only the magnetic toner T is used as a developer. A so-called two-component system composed of toner T and a magnetic carrier can also be used.

  Incidentally, the toner T is a fine powder having a volume average particle diameter of 6 to 12 μm in which additives such as a colorant, a charge control agent and wax are dispersed in a binder resin. Magnetic powders such as ferrite and magnetite having an average particle diameter of 0.01 to 0.50 μm are externally added thereto. The toner T is a consumable that is appropriately supplied from the toner cartridge 29 to the developing device 20.

  The transfer roller 133 transfers the charged toner image formed on the peripheral surface of the photosensitive drum 131 to the paper P with respect to the paper P sent to a position immediately below the photosensitive drum 131.

  The cleaning device 135 is for removing and cleaning the toner T remaining on the peripheral surface of the photosensitive drum 131 after the transfer process. The peripheral surface of the photoconductive drum 131 cleaned by the cleaning device 135 goes to the charging roller 132 again for the next image forming process.

  The fixing unit 14 performs a fixing process by heating the toner image of the paper P that has been transferred by the image forming unit 13. The fixing unit 14 includes a heat roller 141 in which an energization heating element such as a halogen lamp is mounted, and a pressure roller 142 whose peripheral surface is opposed to the lower portion of the heat roller 141.

  Then, the paper P after the transfer process is composed of a heat roller 141 that is driven to rotate clockwise around the roller center, and a pressure roller 142 that is driven to rotate counterclockwise around the roller center. By passing through the nip portion between them, heat from the heat roller 141 is obtained and the fixing process is performed. The paper P subjected to the fixing process is discharged to the paper discharge unit 15 through the paper discharge conveyance path 143.

  The paper discharge unit 15 is formed by recessing the top of the apparatus main body 11, and a paper discharge tray 151 for receiving the discharged paper P is formed at the bottom of the concave portion.

  2 is a partially cut perspective view showing an embodiment of the developing device 20, and FIG. 3 is a sectional view taken along line III-III. 2 and 3, the XX direction is referred to as the left-right direction, the YY direction is referred to as the front-rear direction, and in particular, the -X direction is referred to as the left, the + X direction is referred to as the right, the -Y direction is referred to as the front, and the + Y direction is referred to as the rear. .

  As shown in FIGS. 2 and 3, the developing device 20 includes a first spiral feeder that conveys the toner replenished from the toner cartridge 29 toward the front in a housing 21 having an irregular box shape. 22, the second spiral feeder 23 that conveys the toner delivered from the first spiral feeder 22 backward, and the toner T that is being conveyed by the second spiral feeder 23, and receives the toner T of the photosensitive drum 131. The developing roller 24 is supplied to a latent image area on the peripheral surface, and a blade 30 disposed at a position immediately above the developing roller 24 is mounted.

  As shown in FIGS. 2 and 3, the casing 21 has an L shape when viewed from the front (−Y direction), and the left side is inclined upward from a substantially central position in the left-right direction. A bottom plate 211 whose left end is opposed to the photosensitive drum 131, a top plate 212 that is disposed at the top so as to face the bottom plate 211, and a pair of front-rear direction bridges between the bottom plate 211 and the front and rear ends of the top plate 212. A side plate 213 (a front side plate in FIG. 2 is indicated by a two-dot chain line) and a toner receiving tray 214 provided between the pair of side plates 213 are provided.

  The top plate 212 is formed in a stepped shape with one step higher on the left side. The lower top plate 212a on the right side, the higher top plate 212b on the left side, and the left edge of the lower top plate 212a and the higher top plate. It consists of a vertical top plate 212c installed between the right end edge of the plate 212b. A toner receiving port 212d for receiving toner from the toner cartridge 29 is provided at the rear end of the lower top plate 212a. Further, between the left end edge of the high top plate 212 b and the left end edge of the bottom plate 211, the toner T in the housing 21 is separated from the peripheral surface of the photosensitive drum 131 so as to face the peripheral surface of the photosensitive drum 131. A toner supply port 216 for supplying the toner is opened.

  The toner receiving tray 214 includes a first tray 214 a that houses the first spiral feeder 22, a second tray 214 b that houses the second spiral feeder 23, and a third tray 214 c that is disposed opposite the developing roller 24 at the bottom. It has. The first to third trays 214a, 214b, and 214c are formed in an arc shape that is open upward in a front view as viewed from the front so as to correspond to the corresponding first and second spiral feeders 22 and 23 and the developing roller 24. Is formed. Further, a right side wall 217 is provided at the right end of the first tray 214a, and the right side in the casing 21 is closed by the right side wall 217 being installed between the right ends of the bottom plate 211 and the lower top plate 212a. ing.

  The first spiral feeder 22 includes a first feeder shaft 221 penetrating between a pair of side plates 213 at a position directly above the first tray 214a, and a first spiral that is concentrically fitted and fixed to the first feeder shaft 221. And fins 222. The first spiral fin 222 is formed in a spiral shape in a left-handed state, and conveys the toner T on the first tray 214a forward by rotating the first feeder shaft 221 counterclockwise in a front view. It is like that.

  The second spiral feeder 23 includes a second feeder shaft 231 penetrating between the pair of side plates 213 at a position directly above the second tray 214b, and a second spiral concentrically fitted and fixed to the second feeder shaft 231. And fins 232. The second spiral fin 232 is formed in a spiral shape in a right-handed state, and conveys the toner T on the second tray 214b backward by rotating the second feeder shaft 231 counterclockwise in a front view. It is like that.

  A partition wall 215 is provided between the first and second trays 214a and 214b. A front flow port 215a is opened at the front position of the partition wall 215, and a rear flow port 215b is opened at the rear position. The toner T introduced into the housing 21 from the toner cartridge 29 through the toner receiving port 212d is first transported forward in the first tray 214a by the driving rotation of the first spiral feeder 22, and is distributed in the forward direction. It is carried into the second tray 214b through the opening 215a, is conveyed backward in the second tray 214b by the driving rotation of the second spiral feeder 23, and thereafter circulates between the first and second trays 214a and 214b. However, a part is supplied to the developing roller 24.

  The developing roller 24 includes a roller shaft 241 penetrating between a pair of side plates 213, a cylindrical roller body 242 concentric with the roller shaft 241, a roller body 242, and a roller shaft 241. The roller side magnet 243 is fixed. The roller main body 242 rotates relative to the roller shaft 241, whereas the roller shaft 241 is fixed to the frame F (FIG. 4) of the developing device 20 so as not to rotate.

  The developing roller 24 is set at a position above the third tray 214c so that the circumferential surface of the roller body 242 faces the circumferential surface of the photosensitive drum 131 through the toner supply port 216. Then, the driving force of the driving motor 50 provided at an appropriate position in the apparatus main body 11 is transmitted to the roller main body 242 via a predetermined gear mechanism 51, whereby the roller main body 242 rotates around the roller shaft 241 in the direction shown in FIG. Rotate clockwise. Part of the toner T being circulated and conveyed by the second spiral feeder 23 on the third tray 214c by the rotation of the roller body 242 is supplied to the peripheral surface of the photosensitive drum 131.

  FIG. 4 is a perspective view showing a relative positional relationship between the blade 30, the developing roller 24, and the photosensitive drum 131. The direction display by X and Y in FIG. 4 is the same as in FIG. 2 (X is the left-right direction (−X: leftward, + X: rightward), Y is the front-back direction (−Y: forward, + Y: rearward). )).

  The blade 30 rotates with respect to a latent image region 131b (a region where an electrostatic latent image between two-dot chain lines shown in FIG. 4 is formed) on the peripheral surface of the photosensitive drum 131 by the rotation of the developing roller 24 around the roller shaft 241. The amount of toner T supplied in this way is regulated so as not to be oversupplied. The gap dimension (gap B (see FIG. 3)) between the lower edge of the blade 30 and the peripheral surface of the developing roller 24 is set to 0.1 mm to 0.5 mm in this embodiment.

  Such a range is set for the gap B. If the gap B is less than 0.1 mm, the gap is too narrow and the toner T cannot be properly supplied to the peripheral surface of the photosensitive drum 131. This is because a toner image having an appropriate density is not formed. On the contrary, if the gap B exceeds 0.5 mm, the toner T is excessively supplied to the photosensitive drum 131, and more toner than necessary is supplied to the latent image region 131 b of the photosensitive drum 131. is there.

  The blade 30 includes a thin portion 31 formed at a central position in the longitudinal direction so as to face the latent image region 131b, and a pair of front and rear thick portions 32 formed at both ends. In the present embodiment, the vertical dimension of the blade 30 is set to approximately 25 mm, the thickness dimension of the thin part 31 is set to 1.0 mm, and the thickness dimension of the thick part 32 is set to 2.0 mm. Such dimensions may be appropriately set according to various conditions such as design conditions.

  In the present embodiment, arc members 33 are extended from the right surface of each thick portion 32. This arc member 33 is for preventing the toner T from moving from the peripheral surface of the roller main body 242 toward the end until the toner T reaches the blade 30 in the housing 21. It is formed in a circular arc shape with a central angle set to approximately 180 °. By providing the arc member 33, it is possible to prevent the toner T in the housing 21 from leaking from the toner supply port 216 to the outside via the gap between the end surface of the roller body 242 and the inner surface of the side plate 213.

  In the present embodiment, the blade side magnet 40 is attached to the right side of the thin portion 31 of the blade 30 by sticking or the like. The reason why the blade side magnet 40 is attached to the blade 30 is to make it easy to guide the magnetic lines of force from the roller side magnet 243 provided in the roller body 242 to the blade 30.

  In the present embodiment, the blade-side magnet 40 is configured by arranging a plurality of unit magnets 401 to 406 in series. FIG. 5 is an explanatory view of the blade 30 showing the arrangement state of the unit magnets 401 to 406 as viewed from the right side. In addition, the direction display by Y in FIG. 7 is the same as that in FIG. 2 (−Y: forward, + Y: backward).

  As shown in FIG. 5, in the present embodiment, in the thin portion 31 of the blade 30, the first unit magnet 401, the second unit magnet 402, the third unit magnet from the upstream side (front side) to the downstream side. Six unit magnets 401 to 406 of 403, a fourth unit magnet 404, a fifth unit magnet 405, and a sixth unit magnet 406 are arranged in order.

  The magnetic force (magnetic flux density) of each of the unit magnets 401 to 406 is set so as to gradually decrease from the first unit magnet 401 toward the sixth unit magnet 406. In the present embodiment, the first unit magnet 401 is 700 gauss, the second unit magnet 402 is 650 gauss, the third unit magnet 403 is 600 gauss, the fourth unit magnet 404 is 550 gauss, and the fifth unit magnet 405 is. Is set to 500 gauss, and the sixth unit magnet 406 is set to 450 gauss.

  This is done for the following reason. That is, on the second tray 214 b (FIGS. 2 and 3) in the housing 21, the toner T is conveyed from the upstream side (front) to the downstream side (rear side) by driving the second spiral feeder 23. Go. At this time, the toner T being conveyed is pumped up by the magnetic force and rotation of the developing roller 24, and in the vicinity of the gap between the lower end of the blade 30 and the peripheral surface of the roller main body 242, the peripheral surface of the roller main body 242 and the lower end of the blade 30. A large frictional force is received between them, and charging is promoted due to this friction.

  As described above, the toner T is charged while being moved. As a result, the charge amount is gradually increased from the upstream side toward the downstream side. Therefore, when the magnetic force of the blade-side magnet 40 is constant in the longitudinal direction (front-rear direction) as in the prior art, the toner after the toner T whose charge amount has gradually increased toward the downstream is passed through the blade 30. The toner T on the peripheral surface of the developing roller 24 is more on the downstream side than on the upstream side. As a result, the image quality of the toner image is improved on the peripheral surface of the photosensitive drum 131 where the toner T is transferred from the peripheral surface of the developing roller 24. There is a disadvantage that a difference occurs in the drum center direction.

  Further, when the magnetic force of the blade-side magnet 40 is constant in the longitudinal direction (front-rear direction), the stress applied to the toner by the magnetic force increases as it goes downstream, thereby causing the toner T to be easily deteriorated. Also occurs.

  In order to eliminate the conventional inconvenience, in the present embodiment, the first unit on the most upstream side (front end side) in the conveying direction of the toner T in the axial direction of the second feeder shaft 231 by the second spiral feeder 23. The magnetic force of the magnet 401 is set to the maximum, and the magnetic force is sequentially decreased toward the downstream side.

  As a result, the toner T on the most upstream side becomes larger as the toner T moves downstream, after the rising of the charge up to the required charge amount is secured by the strong magnetic force by the first unit magnet 401. Since the magnetic force of the unit magnets 402 to 406 is reduced so as to be approximately inversely proportional to the charging amount of the toner T, the toner T cut out from the peripheral surface of the developing roller 24 becomes uniform in the longitudinal direction of the developing roller 24. As a result, the image quality of the toner image formed on the peripheral surface of the photosensitive drum 131 becomes uniform, and an appropriate image forming process is realized.

  In addition, the magnetic force of the unit magnets 401 to 406 is set to the maximum magnetic force of the first unit magnet 401 on the most upstream side, and the magnetic force is sequentially decreased toward the downstream side, so that the strength of the magnetic force is the same. In this case, it is possible to prevent the inconvenience that the stress applied to the toner T due to the magnetic force is accumulated and the deterioration of the toner T can be suppressed.

  As described above in detail, the developing device 20 according to the present embodiment includes the developing roller 24 that includes the non-rotating roller-side magnet 243 and rotates around the roller shaft 241, and the peripheral surface of the developing roller 24. And a blade 30 for regulating the layer thickness of the toner T having a magnetic component to be formed.

  According to such a configuration, the toner T in the developing device 20 is transported along the peripheral surface of the developing roller 24 toward the axial direction of the roller shaft 241 by driving the second spiral feeder 23, and It is also conveyed in the rotational direction by rotation. Thus, the toner T being conveyed in both directions is rubbed between the peripheral surface of the developing roller 24 and the edge of the blade 30, and the layer thickness is regulated by the blade 30 while the charging is promoted. In this state, the toner is supplied to the peripheral surface of the photosensitive drum 131.

  Further, the blade 30 is provided with a blade-side magnet 40 in which a plurality (six in this embodiment) of unit magnets 401 to 406 are arranged in series in the longitudinal direction of the blade 30. The toner T on the peripheral surface of the developing roller 24 is guided by the magnetic flux generated by the blade-side magnet 40 and the non-rotating roller-side magnet 243 provided in the developing roller 24, and the tip of the blade 30 is controlled in the layer thickness. And is supplied to the peripheral surface of the photosensitive drum 131.

  In each of the unit magnets 401 to 406, the magnetic force is sequentially decreased from the upstream side to the downstream side along the toner T conveyance direction on the developing roller 24. Accordingly, the magnetic flux density formed by the unit magnets 401 to 406 and the roller-side magnet 243 in the developing roller 24 gradually decreases from the upstream side to the downstream side, so the charge amount of the toner T is caused by friction during conveyance. Even when increasing from the upstream side toward the downstream side, the influence of the magnetic force applied to the toner T is reduced, and thereby the peripheral surface of the developing roller 24 formed by the charge amount of the toner T and the magnetic force of the blade-side magnet 40 The toner T becomes uniform and stress due to the magnetic force applied to the toner T is also reduced.

  As a result, the supply of the toner T supplied from the developing roller 24 to the photosensitive drum 131 is uniform without any difference in the axial direction of the photosensitive drum 131, and the image quality of the toner image on the photosensitive drum 131 is improved. And the deterioration of the toner T due to the magnetic force can be suppressed.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the printer 10 is described as an example of the image forming apparatus to which the developing device 20 is applied. However, the present invention is limited to the printer 10 as the image forming apparatus. Instead, it may be a copying machine or a facsimile machine.

  (2) In the above-described embodiment, a toner cartridge separation type that replenishes the toner T from the toner cartridge 29 that is detachably mounted to the developing device 20 is applied. The toner cartridge 29 may be a so-called developing unit in which the toner cartridge 29 is integrated with the housing 21 of the developing device 20 from the beginning.

  (3) In the above embodiment, the six unit magnets 401 to 406 are employed as the blade-side magnet 40. However, the number is not limited to six, and may exceed six depending on the situation. However, it may be less than six.

  (4) In the above embodiment, the magnetic flux density of each of the unit magnets 401 to 406 is set to 450 gauss to 700 gauss, but is not limited to these ranges, and is 450 gauss depending on the situation. The magnetic flux density of each of the unit magnets 401 to 406 may be set within a range from less than 700 gauss, or from 450 gauss to less than 700 gauss. May be.

  (5) In the above embodiment, a plurality of unit magnets having different magnetic forces (six unit magnets 401 to 406 in the above embodiment) are employed as members that generate magnetic force on the blade 30 side. Instead, one long magnet may be adopted, and the magnetic force may be varied in the longitudinal direction of the long magnet.

  (6) In the above embodiment, the blade 30 is provided with the blade-side magnet 40 so as to generate a magnetic force on the blade 30 side. Instead of this, the blade 30 itself is changed so that the magnetic force is different in the longitudinal direction. You may employ | adopt the magnetized thing.

It is explanatory drawing of the cross sectional view which shows one Embodiment of the internal structure of the printer with which the image development apparatus concerning this invention was applied. It is a partially cut perspective view showing an embodiment of a developing device. FIG. 3 is a cross-sectional view taken along line III-III of the developing device shown in FIG. 2. FIG. 5 is a perspective view showing a relative positional relationship between a blade, a developing roller, and a photosensitive drum. It is explanatory drawing which looked at the braid | blade which shows the arrangement | sequence state of a unit magnet from the left surface side.

Explanation of symbols

10 Printer (image forming device)
DESCRIPTION OF SYMBOLS 11 Apparatus main body 12 Paper storage part 121 Paper cassette 122 Pickup roller 123 Paper feed conveyance path 124 Registration roller pair 13 Image formation part 131 Photosensitive drum (image carrier)
131a drum shaft 131b latent image area 132 charging roller 133 transfer roller 134 exposure device 135 cleaning device 14 fixing unit 141 heat roller 142 pressure roller 143 paper discharge conveyance path 15 paper discharge unit 151 paper discharge tray 20 developing device 21 casing 211 bottom plate 212 Top plate 212a Lower top plate 212b Higher top plate 212c Vertical top plate 212d Toner receiving port 213 Side plate 214 Toner receiving tray 214a First tray 214b Second tray 214c Third tray 215 Partition wall 215a Front flow port 215b Rear flow port 216 Toner Supply port 217 Right side wall 22 First spiral feeder 221 First feeder shaft 222 First spiral fin 23 Second spiral feeder 231 Second feeder shaft 232 Second spiral fin 24 Developing roller 241 B La-axis 242 Roller body 243 Roller side magnet 29 Toner cartridge 30 Blade 31 Thin part 32 Thick part 33 Arc member 40 Blade side magnet 401-406 First to sixth unit magnets 50 Drive motor 51 Gear mechanism B Gap F Frame P Paper P1 Paper bundle T Toner

Claims (3)

A developing roller for supplying toner to the surface of a predetermined image carrier while rotating around an axis in a predetermined housing;
A non-rotating roller-side magnet built in the developing roller;
A blade having a magnetic force that regulates the layer thickness of the toner formed on the peripheral surface of the developing roller,
The developing device according to claim 1, wherein the magnetic force is set so as to sequentially decrease from the upstream side toward the downstream side along the toner conveyance direction in the axial direction on the developing roller. A developing roller for supplying toner to the surface of a predetermined image carrier while rotating around an axis in a predetermined housing;
A non-rotating roller-side magnet built in the developing roller;
A blade for regulating the layer thickness of the toner formed on the peripheral surface of the developing roller;
A blade-side magnet attached to the blade over substantially the entire length in the longitudinal direction;
The developing device according to claim 1, wherein the magnetic force of the blade side magnet is set so that the magnetic force thereof decreases sequentially from the upstream side toward the downstream side along the toner conveyance direction in the axial direction on the developing roller.   The developing device according to claim 2, wherein the blade-side magnet is formed by a plurality of unit magnets arranged in series in a longitudinal direction of the blade.

Images