JP2009210720A - Developing device and image forming device equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of restraining the density nonuniformity of a developer supplied to a developing roll, without providing newly a member, and an image forming device equipped therewith. <P>SOLUTION: A magnetic field formed toward the first stirring conveying auger 88 by a developer drawing-up pole S3 is formed to make a surface of a developer reservoir part 100 not enter into a rotary shaft 88A side over an outside diameter of a spiral blade 88B, by bringing a magnetic force of the developer drawing-up pole S3 into 35 mT. The two-component developer G supplied to the developing roll 86 is thereby limited only to the two-component developer G stirred (arrow mark B in the figure) in an inside of the developer reservoir part 100. That is, only the two-component developer G with a restrained density dispersion by the stirring is supplied to the developing roll 86. The density nonuniformity of the two-component developer G supplied to the developing roll 86 is restrained without providing newly the member, by this manner. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device that develops an electrostatic latent image on a photoreceptor with a developer, and an image forming apparatus including the developing device.

  The developing device is provided with a developing roll for supplying the developer onto the photosensitive member and a supply member that is disposed to face the developing roll and supplies the developer to the developing roll. The supply member includes a screw-shaped spiral blade that rotates and conveys the developer.

  When the developer having a lowered toner concentration and another developer are not sufficiently stirred by the spiral blade, screw pitch-like density unevenness occurs in the developer supplied to the developing roll.

In the developing device of Patent Document 1, a magnet is disposed in the vicinity of the supply member as means for stirring the developer. That is, the screw pitch-shaped density unevenness is suppressed by stirring the developer conveyed by the supply member by the magnetic force of the magnet.
JP 2004-191768 A

  However, since this developing device has a structure that suppresses uneven density of the developer by newly providing a member (magnet), it is an expensive device.

  An object of the present invention is to suppress the uneven density of the developer supplied to the developing roll without providing a new member in consideration of the above fact.

  A developing device according to claim 1 of the present invention includes a fixed magnet having a plurality of magnetic poles provided therein, and pumps up a developer composed of a magnetic carrier and toner by the first magnetic pole in the magnetic poles. A developing roll that holds and rotates to supply toner to a photoreceptor on which an electrostatic latent image is formed and develops the electrostatic latent image, and is arranged to face the developing roll, and rotates to rotate the developing roll A supply member provided with spiral blades and a shaft portion for supplying the developer to the developer roll to form a developer reservoir on the surface of the developer roll facing the first magnetic pole; A developer amount restricting member for restricting the developer amount, and the supply member and the developer amount restricting member are respectively arranged vertically below the developing roll, and the first magnetic pole Magnetic field formed towards the supply member , Wherein the the the developing roll the supply member is formed so as not to enter into the shaft portion than the outer diameter of the surface the helical blade of the developer reservoir at a position facing.

  According to the above configuration, the spiral blade provided on the supply member rotates around the shaft portion and conveys and supplies the developer to the developing roll.

  Further, the first magnetic pole provided inside the developing roll draws up and holds the developer supplied by the supply member. As a result, a developer reservoir is formed on the surface of the developing roll facing the first magnetic pole.

  Here, the magnetic field formed toward the supply member by the first magnetic pole is formed such that the surface of the developer reservoir does not enter the shaft portion side from the outer diameter of the spiral blade. Then, the developer having a lower charge amount than the developer stirred in the developer reservoir does not flow through the tip of the spiral blade, flow on the surface of the developer reservoir, and is directly supplied to the developing roll. That is, the developer supplied to the developing roll is only the developer stirred inside the developer reservoir.

  In this way, by supplying only the developer stirred inside the developer reservoir to the developing roll, uneven density of the developer supplied to the developing roll can be suppressed without providing a new member. .

  A developing device according to a second aspect of the present invention includes a fixed magnet having a plurality of magnetic poles provided therein, and pumps up a developer composed of a magnetic carrier and toner by the first magnetic pole in the magnetic poles. A developing roll that holds and rotates to supply toner to a photoreceptor on which an electrostatic latent image is formed and develops the electrostatic latent image, and is arranged to face the developing roll, and rotates to rotate the developing roll A supply member provided with a spiral blade and a shaft portion for supplying the developer to the developer, and a developer amount regulating member for regulating the developer amount on the developing roll, and the supply member and the development The agent amount regulating member is disposed vertically below the developing roll, and a first developer reservoir is formed on the surface of the developing roll by the first magnetic pole, and the spiral of the supply member The shape of the blade and the shaft In the space formed, a second developer reservoir is formed in accordance with the spacing between the blades, and the first development is performed when the supply member supplies the developer to the development roll. The surface of the agent reservoir and the second developer reservoir are independent at a predetermined distance at a position where the developing roll and the supply member face each other.

  According to the above configuration, the spiral blade provided in the supply member rotates around the shaft portion and conveys and supplies the developer to the developing roll.

  Further, the first magnetic pole provided inside the developing roll draws up and holds the developer supplied by the supply member. As a result, a first developer reservoir is formed on the surface of the developing roll facing the first magnetic pole.

  On the other hand, in the space formed by the spiral blade and the shaft portion of the supply member, a second developer reservoir is formed according to the arrangement interval of the blade. When the supply member supplies the developer to the developing roll, the first developer reservoir and the second developer reservoir are independent at a predetermined distance.

  By making the first developer reservoir and the second developer reservoir independent, the developer flows through the tip of the spiral blade, flows over the surface of the developer reservoir, and is directly supplied to the developing roll. Absent. That is, the developer supplied to the developing roll is only the developer stirred inside the developer reservoir.

  In this way, by supplying only the developer stirred inside the developer reservoir to the developing roll, uneven density of the developer supplied to the developing roll can be suppressed without providing a new member. .

  According to a third aspect of the present invention, in the developing device according to the second aspect, the developer is supplied from the second developer reservoir by the magnetic field formed by the first magnetic pole. The developer moves to the developer reservoir.

  According to the above configuration, the developer moves from the second developer reservoir to the first developer reservoir by the magnetic field formed by the first magnetic pole.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus in which an electrostatic latent image is written by light, and a developer is supplied to the photosensitive member to develop the electrostatic latent image. And a developing device according to claim 1.

  According to the above configuration, the developing device according to any one of claims 1 to 3 develops the electrostatic latent image by forming the electrostatic latent image and supplying the developer to the photosensitive member.

  Here, since the developing device described in any one of claims 1 to 3 is employed, density unevenness of the developer supplied to the developing roll is suppressed. Then, the density unevenness of the developer supplied from the developing roll to the photoconductor can be suppressed, and an output image in which the density unevenness is suppressed can be obtained.

  According to the present invention, in the developing device in which the developer amount regulating member and the supply member are disposed vertically below the development roll, density unevenness that occurs at the blade interval in the axial direction of the supply member is suppressed. Can do.

An example of an image forming apparatus employing the developing device according to the embodiment of the present invention will be described with reference to FIGS.
(overall structure)
First, the overall configuration of the image forming apparatus according to the present embodiment will be described.

  As shown in FIG. 5, in the image forming apparatus 10, process cartridges 14 of four colors (in this embodiment, yellow, magenta, cyan, and black) are arranged in the left-right direction.

  As shown in FIG. 3, the process cartridge 14 includes a photoconductor 16 and a developing device 64. Details of the developing device 64 will be described later.

  As shown in FIG. 5, a paper feed cassette 26 in which the sheet material P is stored is provided at the top of the image forming apparatus 10. A pickup roll 28 that feeds the sheet material P at a predetermined timing is provided above the sheet feeding cassette 26. The sheet material P sent out from the paper feed cassette 26 by the pickup roll 28 is transported along the paper transport path 34 by the transport roll 30 and the registration roll 32 and is sent to a transport device 48 described later.

  On the other hand, the process cartridge 14 is arranged in the order of yellow, magenta, cyan, and black from the upstream side of the paper transport path 34, and the process cartridge 14 is irradiated with scanning light below the process cartridge 14. An exposure device 36 is disposed.

  In the exposure device 36, a semiconductor laser (not shown), a polygon mirror 40, an imaging lens 44, and a mirror 46 are disposed in a housing 38. Light rays from the semiconductor laser are deflected and scanned by the polygon mirror 40. The photosensitive member 16 is irradiated through the imaging lens 44 and the mirror 46. Thereby, an electrostatic latent image corresponding to the image information is formed on the photosensitive member 16.

  A transport device 48 is disposed at a position facing the photoconductor 16 across the paper transport path 34. The conveying device 48 includes a pair of stretching rolls 51 and 52 provided along the plurality of process cartridges 14, and a conveying belt 53 wound around the stretching rolls 51 and 52. The tension roll 52 is rotated by a motor (not shown) so that the transport belt 53 moves.

  Further, an adsorbing roll 55 is provided in the vicinity of the stretching roll 51 arranged on the sheet feeding cassette 26 side, and when a voltage is applied to the adsorbing roll 55, the sheet material P is applied to the conveying belt 53. Is electrostatically attracted.

In addition, transfer rolls 54 are disposed at positions on the back surface of the conveyance belt 53 and facing the photoconductors 16 of the respective colors. The toner image on the photoconductor 16 is transferred to the sheet material P conveyed by the conveying belt 53 by the transfer roll 54 and fixed by the fixing device 56. Then, the sheet material P on which the toner image is fixed is discharged to the discharge tray 60 by the discharge roll 58.
(Main part configuration)
Next, the developing device 64 in this embodiment will be described.

  As shown in FIG. 3, the developing device 64 visualizes the electrostatic latent image on the photoconductor 16 facing the photoconductor 16 with a two-component developer G composed of a nonmagnetic toner T and a magnetic carrier. The developing unit 68 and a main toner replenishing unit 70 that replenishes the developing unit 68 with nonmagnetic toner T are configured.

  The developing unit 68 has a housing 80. The housing 80 is provided below the photoconductor 16 and has an opening 82 that opens toward the photoconductor 16. Further, a developer storage chamber 84 is formed in the housing 80, and a two-component developer G composed of a nonmagnetic toner T and a magnetic carrier can be stored in the developer storage chamber 84. .

  Further, a developing roll 86 having a diameter of 18 mm is provided in the housing 80 so as to be partially exposed from the opening 82 of the housing 80, and the developing roll 86 is rotatably supported by the housing 80. . A gear 86C (see FIG. 4) is fixed to the end of the developing roll 86, so that the rotational force from the motor is transmitted to the gear 86C, and the developing roll 86 rotates via the gear 86C. Yes. Further, the peripheral speed of the developing roll 86 is set so that the electrostatic latent image on the photosensitive member 16 is rubbed at a speed ratio of 1.8 times and visualized with the two-component developer G.

  Further, the developing roll 86 is rotatable and has a thin cylindrical cylindrical sleeve 86A made of aluminum having a surface of which 50 to 100 V-shaped grooves having a depth of 90 μm are formed, and a fixed columnar magnet roll. 86B.

  Specifically, as shown in FIG. 1, the magnet roll 86B of the developing roll 86 has a total of five magnetic poles of N polarity N1, N2 and S polarity S1, S2, S3, and the circumferential directions S1, N1 , S2, S3, and N2 are arranged at predetermined intervals.

  A developing pole S1 is disposed at a position facing the developing area of the photosensitive member 16, and the developer amount on the surface of the nonmagnetic sleeve 86A is set upstream of the developing pole S1 in the rotation direction of the developing roll 86. A developer regulating pole N2 having a magnetic force of 750 mT (millitesla) to be regulated is disposed opposite to the plate-like developer regulating plate 50 that regulates the layer thickness of the two-component developer G. The developer regulating plate 50 is disposed substantially below the developing roll 86 in the vertical direction.

  A developer peeling pole S2 and a developer pumping pole S3 (first magnetic pole) having a magnetic force of 35 mT (millitesla) are disposed downstream of the developing pole S1 and upstream of the developer regulating pole N2. The transport electrode N1 is disposed between the developing electrode S1 and the developer peeling electrode S2.

  With this configuration, the developing pole S <b> 1 generates magnetic lines of force in a direction that causes the two-component developer G on the developing roll 86 to move toward the photoconductor 16. Further, the developer stripping pole S2 and the developer pumping pole S3 having the same polarity are adjacent to each other, thereby generating a magnetic force line in a direction in which the two-component developer G on the developing roll 86 is separated from the developing roll 86. Further, the developer pumping pole S <b> 3 generates a magnetic force line in a direction in which the two-component developer G in the developer reservoir 100 (first developer reservoir), which will be described later, is attracted to the developing roll 86. Further, the developer regulating pole N2 generates a magnetic force line in a direction in which the two-component developer G is directed toward the developer regulating plate 50.

  That is, in the two-component developer G adsorbed on the surface of the sleeve 86A in the vicinity of the developer pumping pole S3, the sleeve 86A rotates along the rotation direction (arrow A). Along with this, the developer regulating electrode N2 → the developing electrode S1 → the conveying electrode N1 is conveyed. When passing through the developer regulating pole N2, the layer thickness of the two-component developer G is made uniform by the developer regulating plate 50, and the nonmagnetic toner T on the magnetic brush moves to the photosensitive member 16 near the developing pole S1, and the sleeve On the surface of 86A, a magnetic brush which is almost only a magnetic carrier remains. The magnetic brush including only the magnetic carrier falls off the surface of the sleeve 86A at the developer peeling pole S2 and returns to the developer reservoir 100 as the sleeve 86A rotates.

  The distance between the developer regulating plate 50 and the sleeve 86A is determined so that the two-component developer G passing through the gap between the developer regulating plate 50 and the sleeve 86A is regulated to 300 to 700 g / m2. .

  On the other hand, a first agitating / conveying auger 88 having a diameter of 18 mm as a supply member is disposed along the axial direction of the developing roll 86 at a distance of 7.6 mm from the developing roll 86, vertically below the developing roll 86. ing. Further, a second stirring / transporting auger 89 having a diameter of 18 mm is disposed adjacent to the first stirring / transporting auger 88.

  As shown in FIG. 4, the first stirring / conveying auger 88 and the second stirring / conveying auger 89 include rotation shafts 88 </ b> A and 89 </ b> A, respectively, and are rotatably supported on the peripheral wall of the housing 80. The first stirring / conveying auger 88 and the second agitating / conveying auger 89 are formed by spirally rotating spiral blades 88B and 89B at a predetermined pitch on the rotating shaft 88A and the rotating shaft 89A. ing.

  Further, gears 88C and 89C are fixed to the ends of the rotary shaft 88A and the rotary shaft 89A, respectively, and a rotational force from a motor (not shown) is transmitted to the gear, and the first agitating and conveying auger 88 is transmitted via the gear. And the 2nd stirring conveyance auger 89 rotates, respectively. When the first agitating / conveying auger 88 and the second agitating / conveying auger 89 are rotated, the two-component developer G accommodated in the developer accommodating chamber 84 is agitated by the spiral blade 88B and the spiral blade 89B in the direction of the arrow in FIG. To be transported to.

  A partition wall 90 is formed between the first stirring and transporting auger 88 and the second stirring and transporting auger 89, and the first stirring and transporting auger 88 is disposed in the developer storage chamber 84 by the partition wall 90. It is divided into an area (first stirring path) 92 and an area (second stirring path) 93 in which the second stirring / conveying auger 89 is provided.

  A communication port 94 and a communication port 95 are formed at both ends in the longitudinal direction of the partition wall 90. The first stirring path 92 and the second stirring path 93 are communicated with each other through the communication ports 94 and 95, and the two-component developer G in the developer storage chamber 84 is supplied to the first stirring and transporting auger 88 and the second stirring and transporting. The two-component developer G is circulated between the first stirring path 92 and the second stirring path 93 while being transported while being stirred in the first stirring path 92 and the second stirring path 93 by the rotation of the auger 89. It has become.

  Further, as shown in FIG. 1, the two-component developer G transported by the first stirring transport auger 88 is supplied to the developing roll 86 so that the developer reservoir 100 is formed around the developing roll 86. It has become. The two-component developer G in the developer reservoir 100 is agitated (arrow B in the figure) inside the developer reservoir 100 and supplied to the sleeve 86A of the developing roll 86.

  Here, FIG. 2 shows a view of the developing roll 86 and the first agitation transport auger 88 in FIG. The magnetic force of the developer pumping pole S3 that pumps the two-component developer G from the developer reservoir 100 and adheres to the surface of the sleeve 86A is set to 35 mT, and is formed toward the first agitating and conveying auger 88 by the pumping pole S3. The magnetic field is formed so that the surface 100A of the developer reservoir 100 does not enter the rotation shaft 88A side of the outer diameter of the spiral blade 88B.

  On the other hand, the developer G stirred and conveyed by the first agitating / conveying auger 88 has a substantially three-shaped developer reservoir 101 (second development) corresponding to the arrangement interval of the spiral blades 88B (so-called pitch of the spiral blades 88B). Agent reservoir).

  That is, when the first stirring / conveying auger 88 supplies the developer G to the developing roll 86, the surface 100A of the developer reservoir 100 and the developer reservoir 101 are independent at a predetermined distance.

  As a result, as shown in FIG. 1, the two-component developer G is agitated (arrow B in the figure) inside the developer reservoir 100 and supplied to the sleeve 86 </ b> A of the developing roll 86.

  On the other hand, as shown in FIG. 3, the main toner supply unit 70 adjacent to the developing unit 68 is provided with a toner storage chamber 150 in which the nonmagnetic toner T for supply is stored. A toner stirring and conveying member 152 is provided in the toner storage chamber 150 along the axial direction of the developing roll 86.

  The toner agitating / conveying member 152 includes a rotation shaft 152 </ b> A and is rotatably supported on the peripheral wall of the housing 80. Blades 152B are formed on the rotating shaft 152A at a predetermined pitch.

  A gear (not shown) is fixed to the end portion of the rotating shaft 152A. When the toner agitating / conveying member 152 is rotated via the gear by the rotational force from the motor (not shown), the blade 152B causes the toner storage chamber to rotate. The nonmagnetic toner T in 150 is conveyed in the direction of the arrow in FIG. 4 while being stirred.

  On the other hand, as shown in FIG. 3, a wall portion 154 is provided on the developer storage chamber 84 side of the toner storage chamber 150. From the lower part of the wall portion 154, the curved wall 156 extends toward the toner storage chamber 150, and the partition wall 157 extends toward the developer storage chamber 84, so that a tunnel-shaped dispense chamber is formed between the bottom plates of the housing 80. 158 is provided.

  As shown in FIG. 4, an opening 162 is formed in the vicinity of one end in the longitudinal direction of the curved wall 156 so as to communicate the toner storage chamber 150 and the dispense chamber 158. As a result, the nonmagnetic toner T accommodated in the toner accommodating chamber 150 is conveyed through the toner accommodating chamber 150 while being agitated by the toner agitating / conveying member 152, and is sent to the dispensing chamber 158 from the opening 162. Yes.

  On the other hand, a toner supply port 164 is formed in the vicinity of the other end in the longitudinal direction of the partition wall 157 so as to communicate the dispense chamber 158 and the developer storage chamber 84. As a result, the nonmagnetic toner T in the dispense chamber 158 is conveyed through the dispense chamber 158 while being stirred by the dispense auger 160, and is sent from the toner supply port 164 to the developer storage chamber 84.

As shown in FIG. 3, the toner supply port 164 is formed so that the lower end portion is positioned below the surface position of the two-component developer G stored in the developer storage chamber 84. As a result, at least a part of the toner supply port 164 is buried in the two-component developer G accommodated in the developer accommodating chamber 84, and the non-feed fed from the dispense chamber 158 to the developer accommodating chamber 84 is not performed. The magnetic toner T enters the two-component developer G and is easily mixed with the two-component developer G stored in the developer storage chamber 84. As described above, the two-component developer G stirred by the dispense auger 160, the first stirring and transporting auger 88, and the second stirring and transporting auger 89 is adsorbed to the surface of the developing roll 86 by a magnetic force.
(Function)
In the image forming apparatus 10 configured as described above, an image is formed as follows.

  First, a charging roll (not shown) uniformly charges the surface of the photoconductor 16 at a predetermined charged portion potential.

  Next, as shown in FIG. 3, exposure is performed by the exposure device 36 (see FIG. 5) so that the image portion on the charged photoconductor 16 has a predetermined exposure portion potential, and an electrostatic latent image is formed. The That is, a latent image corresponding to an image is formed on the photosensitive member 16 by turning on and off a semiconductor laser (not shown) based on image data supplied from a control device (not shown).

  Further, the two-component developer G stirred by the dispense auger 160, the first stirring and transporting auger 88, and the second stirring and transporting auger 89 is applied to the magnet roll 86B on the nonmagnetic sleeve 86A of the developing roll 86 of the developing device 64. The developer is attracted by the magnetic force of the developer pumping pole S3. The two-component developer G adsorbed on the non-magnetic sleeve 86A is scraped off by passing through the gap between the developer regulating plate 50 and the developing roll 86, and the layer thickness of the two-component developer G is increased. It becomes uniform.

  Further, a predetermined developing bias voltage is applied to the developing roller 86 for each color from a power supply device (not shown), and the electrostatic latent image on the photosensitive member 16 is static when passing through the position of the developing roller 86. The non-magnetic toner T of the two-component developer G adheres to the electrostatic latent image by electric force and is visualized as a toner image.

  Therefore, as shown in FIG. 5, the sheet material P placed in the paper feed cassette 26 is sent out to the paper transport path 34 by the pick-up roll 28, and is further predetermined by the transport roll 30 and the registration roll 32. It is conveyed at the timing. Then, the sheet material P passes between the photoreceptor 16 and the transfer roll 54, and the toner image is transferred to the sheet material P. The transferred toner image is fixed by the fixing device 56, and the sheet material P on which the toner image is fixed is discharged to the discharge tray 60 by the discharge roll 58.

  Here, as shown in FIG. 2, by setting the magnetic force of the developer pumping pole S3 to 35 mT, the magnetic field formed by the pumping pole S3 toward the first agitating / conveying auger 88 is generated in the developer reservoir 100. The surface 100A is formed so as not to enter the rotating shaft 88A side from the outer diameter of the spiral blade 88B.

  As a result, as shown in FIG. 1, the two-component developer G supplied to the developing roll 86 is agitated (arrow B in the figure) inside the developer reservoir 100, and the agitated two-component developer G Only the sleeve 86A of the developing roll 86 is supplied. That is, only the two-component developer G that has been stirred and whose density variation is suppressed is supplied to the developing roll 86.

  Thus, density unevenness of the two-component developer G supplied to the developing roll 86 can be suppressed without providing a new member.

  Further, by suppressing the density unevenness of the two-component developer G supplied to the developing roll 86, the density unevenness of the toner image transferred to the sheet material P can also be suppressed.

  Here, the inventor of the present application tested the image forming apparatus provided with the conventional developing device and the image forming apparatus 10 according to the present embodiment, and confirmed density unevenness of the toner image output to the sheet material P. .

  First, a confirmation method and the like will be described.

  As the two-component developer G, a resin-dispersed spherical magnetic carrier having an average diameter of 35 μm and an amorphous toner having an average diameter of 5.5 μm prepared by a polymerization method are used and mixed at a toner concentration of 8%. 180 g of component developer G was used.

  The developing device is attached to the image forming apparatus, and an image is formed on 100 sheets of sheet material P with a print coverage of 5%. During the image formation, the toner is supplied to the developing device from the end of the second agitating / conveying auger so as to maintain the initial toner concentration of 8%. After forming an image on 100 sheets of sheet material P, the developing device is taken out and the state of the developer reservoir is confirmed.

  Furthermore, the developing device is returned to the image forming apparatus, and the density unevenness of the output image is confirmed by continuously forming an image on P10 sheets of the sheet material P with 80% of the entire surface halftone with easy to detect the image density unevenness due to the auger pitch. did.

  Then, based on the confirmation method described above, the conventional developing device 200 and the developing device 200 are attached to the image forming apparatus, and density unevenness of the output image is confirmed.

  As shown in FIG. 6, the magnetic force of the developer pumping pole S3 provided on the conventional developing roll 202 is 55 mT in order to pump a large amount of the two-component developer G from the developer reservoir 204.

  First, after forming an image on 100 sheets of sheet material P, the developing device 200 was taken out and the state of the developer reservoir 204 was confirmed. FIG. 7 is a view of FIG. 6 as viewed from the direction of the arrow Q. As shown in FIG. 7, the developer pumping pole S3 pumps a large amount of the two-component developer G, so that the developer reservoir 204 becomes larger, and the surface 204A of the developer reservoir 204 becomes the first agitating / conveying auger 206. It was confirmed that the spiral blade 206A entered the rotating shaft side from the outer diameter.

  Next, the developing device 200 is returned to the image forming apparatus, and an image is continuously formed on P10 sheets of the sheet material P with a full halftone of 80% print coverage in which image density unevenness due to the auger pitch is easy to be detected. Unevenness was confirmed. As shown in FIG. 8, the output image had density unevenness in the tilt direction.

  That is, when the developer regulating plate 50 and the first agitating and transporting auger 88 as the supply member are disposed vertically downward with respect to the developing roll, the (first) developer reservoir 100 is connected to the developing roll 50. And the first agitating / conveying auger 88 are formed so as to be close or intruded at a position where they face each other. Then, as shown in FIG. 6, the two-component developer G transported by the first stirring transport auger 206 is supplied directly to the surface 204A of the developer reservoir 204 through the tip of the spiral blade 206A. ing. Specifically, the two-component developer G directly supplied to the surface 204A of the developer reservoir 204 moves along the surface 204A (arrow C shown in FIG. 6) and is stirred inside the developer reservoir 204. Without being supplied to the developing roll 202.

  As a result, the two-component developer G supplied to the surface of the developing roll 202 without being stirred inside the developer reservoir 204 and the developer reservoir 204 are stirred (arrow D shown in FIG. 6). The two-component developer G is supplied to the developing roll 202. Since the former developer has a lower chargeability than the latter developer, it tends to be developed with respect to a latent image of the same potential on the photoreceptor, and the density tends to be high. Therefore, uneven density in the inclination direction corresponding to the interval between the blades arranged in the axial direction of the first agitating / conveying auger 88 is formed on the image (FIG. 8).

  Next, based on the confirmation method described above, the developing device 64 of the present application and the developing device 64 were attached to the image forming apparatus 10 to confirm density unevenness of the output image.

  As shown in FIG. 1, the magnetic force of the developer pumping pole S3 provided on the developing roller 86 of the present application is 35 mT, which is weaker than the conventional developer pumping pole S3.

  First, after forming an image on 100 sheets of sheet material P, the developing device 64 was taken out and the state of the developer reservoir 100 was confirmed. As shown in FIG. 2, by making the magnetic force of the developer pumping pole S3 weaker than the magnetic force of the conventional developer pumping pole S3, the developer reservoir 100 becomes smaller. As described above, the developer reservoir 100 The surface 100 </ b> A (see FIG. 1) is prevented from entering the rotation shaft 88 </ b> A side of the outer diameter of the spiral blade 88 </ b> B of the first agitating / conveying auger 88.

  Next, the developing device 64 is returned to the image forming device 10, and an image is continuously formed on P10 sheets of the sheet material P with a halftone of 80% of the print coverage in which it is easy to detect image density unevenness due to the auger pitch. Density unevenness was confirmed. There was no density unevenness in the output image.

  That is, as shown in FIG. 1, the two-component developer G is supplied to the sleeve 86 </ b> A of the developing roll 86 after being stirred (arrow B in the drawing) inside the developer reservoir 100. For this reason, by suppressing the density unevenness of the two-component developer G supplied to the developing roll 86, the density unevenness of the output image is suppressed.

  Thus, as can be seen from the confirmation result of the inventors of the present application, by setting the magnetic force of the developer pumping pole S3 to 35 mT, the magnetic field formed by the pumping pole S3 toward the first stirring / conveying auger 88 is By forming the developer reservoir 100 so that the surface of the developer reservoir 100 does not enter the rotation shaft 88A side of the outer diameter of the spiral blade 88B, density unevenness of the two-component developer G supplied to the developing roll 86 is suppressed. I understand that.

  In order to confirm the positional relationship between the developer reservoir and the first stirring / conveying auger, an image is formed on several tens to hundreds of sheet materials P, and the developing device 64 for the two-component developer G is used. What is necessary is just to confirm when the flow of is stabilized. When the image forming apparatus 10 is actually used, there are fluctuations in the developer amount, such as fluctuations in toner density and carrier adhesion to the photoconductor 16, but it is only necessary to satisfy the scope of the present invention in the initial state. This is because the decrease in the developer amount due to the carrier outflow reduces the amount of developer conveyed by the auger, and the positional relationship between the surface 100A of the developer reservoir 100 and the tip of the first agitating / conveying auger 88 does not change. . Conversely, when the toner concentration increases, the volume of the developer increases, but the magnetization as the developer also decreases, so the positional relationship between the surface 100A of the developer reservoir 100 and the tip of the first agitation transport auger 88 changes. There is no.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above embodiment, by changing the magnetic force of the developer pumping pole S3, the surface 100A of the developer reservoir 100 is prevented from entering the rotating shaft 88A side from the outer diameter of the spiral blade 88B. The arrangement position of the agitating / conveying auger may be adjusted, or the diameter of the spiral blade may be changed so that the surface 100A of the developer reservoir 100 does not enter the rotating shaft 88A side of the outer diameter of the spiral blade 88B. Further, by changing the magnetic force and specific gravity of the magnetic carrier, the surface 100A of the developer reservoir 100 may be prevented from entering the rotating shaft 88A side from the outer diameter of the spiral blade 88B, and these parameters are combined. May be.

It is the side view which showed the developing roll, the 1st stirring conveyance auger, etc. which were employ | adopted for the image development apparatus concerning embodiment of this invention. It is the front view which showed the developing roll, the 1st stirring conveyance auger, and the developer reservoir which were employ | adopted as the developing device which concerns on embodiment of this invention. 1 is a side view showing a process cartridge in which a developing device according to an embodiment of the present invention is employed. FIG. 3 is a cross-sectional view of the inside of the developing device according to the embodiment of the present invention as viewed from above. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is the side view which showed the developing roll, the 1st stirring conveyance auger, etc. which were employ | adopted as the developing apparatus as a comparative example of embodiment of this invention. It is the front view which showed the developing roll, the 1st stirring conveyance auger, and the developer storage part which were employ | adopted as the developing apparatus as a comparative example of embodiment of this invention. It is drawing which showed the output image output by the image development apparatus as a comparative example of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 16 Photoconductor 64 Developing apparatus 86 Developing roll 86B Magnet roll (magnet)
88 First agitating and transporting auger (feeding member)
88A Rotating shaft (shaft)
88B Spiral blade (spiral blade)
100 developer reservoir (first developer reservoir)
100A Surface 101 Developer reservoir (second developer reservoir)

Claims (4)

A fixed magnet having a plurality of magnetic poles provided therein is provided, and a developer composed of a magnetic carrier and toner is pumped and held by the first magnetic pole of the magnetic poles and rotated to form an electrostatic latent image. A developing roll for supplying toner to the photoconductor and developing the electrostatic latent image;
A spiral blade disposed opposite to the developing roll, rotating to supply the developer to the developing roll, and forming a developer reservoir on a surface of the developing roll facing the first magnetic pole; A supply member provided with a shaft portion;
A developer amount regulating member that regulates the amount of developer on the developing roll;
With
The supply member and the developer amount regulating member are respectively arranged vertically below the developing roll,
The magnetic field formed toward the supply member by the first magnetic pole is such that the surface of the developer reservoir at a position where the developing roll and the supply member face each other than the outer diameter of the spiral blade. A developing device characterized by being formed so as not to enter the shaft side. A fixed magnet having a plurality of magnetic poles provided therein is provided, and a developer composed of a magnetic carrier and toner is pumped and held by the first magnetic pole of the magnetic poles and rotated to form an electrostatic latent image. A developing roll for supplying toner to the photoconductor and developing the electrostatic latent image;
A supply member provided with a spiral blade and a shaft that are arranged opposite to the developing roll and rotate to supply the developer to the developing roll;
A developer amount regulating member that regulates the amount of developer on the developing roll;
With
The supply member and the developer amount regulating member are respectively arranged vertically below the developing roll,
A first developer reservoir is formed on the surface of the developing roll by the first magnetic pole,
In the space formed by the spiral blades and the shaft portion of the supply member, a second developer reservoir is formed according to the arrangement interval of the blades.
When the supply member supplies the developer to the developing roll, the developing roll and the supply member face each other between the surface of the first developer reservoir and the second developer reservoir. A developing device characterized by being independent at a predetermined distance in position.   3. The developer is supplied by moving the developer from the second developer reservoir to the first developer reservoir by a magnetic field formed by the first magnetic pole. The developing device according to 1. A photoreceptor on which an electrostatic latent image is written by light;
The developing device according to claim 1, wherein a developer is supplied to the photosensitive member to develop the electrostatic latent image;
An image forming apparatus comprising: