JP2013064938A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device with a large charge amount on developer and an image forming apparatus.SOLUTION: A developing device 14Y includes: a developer container 140 containing developer including tonner and magnetic body; a conveyance member 143 having a rotary shaft and a spiral blade 1432 attached on a rotary shaft 1431 disposed in the developer container 140 leaving a space G between the blade 1432 and the inner wall 1403 of the developer container 140 to convey the developer in the developer container 140 in an extending direction of the rotary shaft while rotating and mixing the developer; a magnet 144 disposed facing to the outer wall 1402 in an extending direction of the developer container 140 to attract the developer in the developer container 140; and a conveyance mechanism 145 that conveys the magnet along the outer wall in the extending direction.

Description

  The present invention relates to a developing device and an image forming apparatus.

  For example, in Patent Document 1, in a developing device that stirs and charges a developer composed of a non-magnetic toner and a magnetic carrier with a developer stirring screw, the developer stirring screw is placed outside the developer container in order to promote charging. The structure which has arrange | positioned the magnet roller extended in the longitudinal direction is shown.

  Further, Patent Document 2 shows a configuration in which an electromagnet is fixed to a developing tank in a developing device in which a stirring member is disposed in the developing tank, and when the toner is supplied, the stirring member is rotated at a high speed and the electromagnet is energized. ing.

JP 2006-227392 A JP 2010-164651 A

  An object of the present invention is to provide a developing device and an image forming apparatus having a large charge amount of a developer.

The developing device according to claim 1 is:
A developer container containing a developer containing toner and a magnetic material;
It has a rotating shaft and a spiral blade provided around the rotating shaft, and is disposed in the developer container with a gap between the inner wall of the developer container and the blade, and rotates. A conveying member that conveys the developer in the developer container in the extending direction of the rotating shaft while stirring the developer in the developer container;
A magnet that is arranged opposite to the outer wall of the developer container that extends in the extending direction, and that attracts the developer in the developer container with a magnetic force;
And a transfer mechanism for transferring the magnet along the outer wall in the extending direction.

  The developing device according to a second aspect is characterized in that the magnet rotates about an axis that intersects the surface of the outer wall.

  The developing device according to a third aspect is characterized in that the blade is made of a magnetic material.

An image forming apparatus according to claim 4
A developing object on which an electrostatic latent image is formed on the surface and the electrostatic latent image is developed with toner;
A developing device for developing the object to be developed with toner,
A developer container containing a developer containing toner and a magnetic material;
It has a rotating shaft and a spiral blade provided around the rotating shaft, and is disposed in the developer container with a gap between the inner wall of the developer container and the blade, and rotates. A conveying member that conveys the developer in the developer container in the extending direction of the rotating shaft while stirring the developer in the developer container;
A magnet that is arranged opposite to the outer wall of the developer container that extends in the extending direction, and that attracts the developer in the developer container with a magnetic force;
And a transfer mechanism for transferring the magnet along the outer wall in the extending direction.

  The developing device according to the first aspect and the image forming apparatus according to the fourth aspect have a larger charge amount of the developer than the case where the configuration is not provided.

  In the developing device according to the second aspect, the charge amount of the developer is larger than that in the case where the magnet does not rotate.

  In the developing device according to the third aspect, the charge amount of the developer is larger than that in the case where the blade is made of a non-magnetic material.

1 is a configuration diagram illustrating an embodiment of an image forming apparatus of the present invention. FIG. 2 is a perspective view of the developing device shown in FIG. 1 as viewed from above. It is a side view of a developing device. It is a longitudinal cross-sectional view of a developing device. It is a graph which shows a toner charge amount.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram showing an embodiment of an image forming apparatus of the present invention.

  The image forming apparatus 1 shown in FIG. 1 has image forming units 10Y, 10M, 10C, and 10K arranged in parallel for each color of yellow (Y), magenta (M), cyan (C), and black (K). The tandem type color printer is capable of printing a single color image and printing a full color image composed of four color toner images. The image forming apparatus 1 includes toner cartridges 18Y, 18M, 18C, and 18K that store toners of CMYK colors.

  Since the four image forming units 10Y, 10M, 10C, and 10K have substantially the same configuration, the image forming unit 10Y corresponding to yellow will be described as a representative example. The image forming unit 10Y includes a photoreceptor 11Y, a charger 12Y, an exposure device 13Y, a developing device 14Y, a primary transfer device 15Y, and a photoreceptor cleaner 16Y.

  The photoconductor 11Y has a photoconductor layer on a cylindrical substrate, holds an image formed on the surface, and rotates in the direction of arrow A around the axis of the cylinder. The charger 12Y, the exposure device 13Y, the developing device 14Y, the primary transfer device 15Y, and the photoconductor cleaner 16Y are sequentially arranged around the photoconductor 11Y.

  The charger 12Y charges the surface of the photoreceptor 11Y. The charger 12Y is a charging roll that contacts the surface of the photoreceptor 11Y. A voltage having the same polarity as that of the toner in the developing device 14Y is applied to the charging roll, and the surface of the contacted photoreceptor 11Y is charged. As the charger 12Y, a corona discharger that is not in contact with the photoreceptor 11Y can be employed in addition to the charging roll.

  The exposure device 13Y includes a light emitter that emits laser light based on an image signal supplied from the outside of the image forming apparatus 1, and a rotary polygon mirror that scans the photoconductor 11Y with the laser light. By irradiating 11Y with laser light, the surface of the photoreceptor 11Y is exposed.

  The developing device 14Y develops the surface of the photoreceptor 11Y using a two-component developer composed of toner and a magnetic carrier. Toner is supplied from the toner cartridge 18Y to the developing device 14Y. The toner is mixed with the magnetic carrier in the developing device 14Y. The magnetic carrier is obtained, for example, by applying a resin coating to the surface of iron powder. The toner particles have, for example, a binder resin, a colorant, and a release agent. The developing device 14Y charges the toner and the magnetic carrier by stirring the developer in which the magnetic carrier particles and the toner particles are mixed, and develops the surface of the photoreceptor 11Y with the charged toner. The magnetic carrier corresponds to an example of the magnetic material referred to in the present invention.

  The primary transfer unit 15Y is a roll facing the photoconductor 11Y with the intermediate transfer belt 30 interposed therebetween. The primary transfer unit 15Y has a conductive elastic layer on the surface, and a toner image on the photoreceptor 11Y is statically applied to the intermediate transfer belt 30 by applying a voltage having a polarity opposite to the charging polarity of the toner. Electrosuction. The photoconductor cleaner 16Y has a cleaning blade that contacts the surface of the photoconductor 11Y, and cleans the surface of the photoconductor 11Y after transfer.

  The image forming apparatus 1 also includes an intermediate transfer belt 30, a fixing device 60, a paper transport unit 80, and a control unit 1 </ b> A that controls each part of the image forming apparatus 1. The intermediate transfer belt 30 is an endless belt made of a resin material containing an antistatic agent. The intermediate transfer belt 30 is stretched around belt support rolls 31 to 35 and circulates in the direction indicated by the arrow B passing through the image forming units 10Y, 10M, 10C, and 10K and the secondary transfer unit 50. The toner images of the respective colors are transferred to the intermediate transfer belt 30 from the image forming units 10Y, 10M, 10C, and 10K. The intermediate transfer belt 30 moves while holding the toner images of these colors.

  The secondary transfer device 50 is a roll that rotates with the intermediate transfer belt 30 and the paper sandwiched between the secondary transfer unit 50 and the backup roll 34 that is one of the belt support rolls 31 to 35. The secondary transfer unit 50 has a conductive elastic layer on the surface, and a voltage having a polarity opposite to the charging polarity of the toner is applied to electrostatically attract the toner image on the intermediate transfer belt 30 to the sheet. . The belt cleaner 70 scrapes off the toner on the intermediate transfer belt 30 by bringing a blade into contact with the intermediate transfer belt 30.

  The fixing device 60 fixes the toner on the paper. The fixing device 60 includes a heating roll 61 and a pressure roll 62, and the heating roll 61 includes a heater. The heating roll 61 and the pressure roll 62 fix the toner image on the paper by passing the paper on which the toner image before fixing is formed sandwiched therebetween.

  The paper transport unit 80 includes a take-out roll 81 that takes out the paper stored in the paper container T, a scooping roll 82 that picks up the picked-up paper, a transport roll 83 that transports the paper, and a resist that transports the paper to the secondary transfer device 50. And a discharge roll 86 for discharging the paper to the outside. The paper transport unit 80 transports along a paper transport path R that passes through the secondary transfer device 50 and the fixing device 60.

  The basic operation of the image forming apparatus 1 shown in FIG. 1 will be described. In the yellow image forming unit 10Y, the photoreceptor 11Y is rotationally driven in the direction of arrow A, and a charge is applied to the surface of the photoreceptor 11Y by the charger 12Y. . The exposure device 13Y irradiates the photoconductor 11Y with exposure light corresponding to data corresponding to each color in the image signal. The exposure device 13Y forms an electrostatic latent image on the surface of the photoconductor 11Y by irradiating the surface of the photoconductor 11Y with exposure light based on an image signal corresponding to yellow among image signals supplied from the outside. . Yellow toner is supplied from the toner cartridge 18Y to the developing device 14Y. The developing device 14Y forms a toner image by developing the electrostatic latent image with toner. The photoconductor 11Y rotates while holding the yellow toner image formed on the surface. The toner image formed on the surface of the photoreceptor 11Y is transferred to the intermediate transfer belt 30 by the primary transfer unit 15Y. After transfer, the toner remaining on the photoreceptor 11Y is collected and removed by the photoreceptor cleaner 16Y.

  The intermediate transfer belt 30 is looped around the support rolls 31 to 35 and moved in the direction of arrow B. The image forming units 10M, 10C, and 10K corresponding to colors other than yellow form toner images corresponding to the respective colors in the same manner as the image forming unit 10Y, and are transferred to the intermediate transfer belt 30 by the image forming unit 10Y. The toner images of the respective colors are transferred so as to overlap the toner images.

  The paper P is taken out from the paper container T by the take-out roll 81. The paper P is transported along the paper transport path R in the direction of arrow C toward the secondary transfer device 50 by the transport roll 83 and the registration roll 84. The registration roll 84 sends the paper P to the secondary transfer device 50 based on the timing at which the toner image is transferred onto the intermediate transfer belt 30. The secondary transfer device 50 transfers the toner image on the intermediate transfer belt 30 to the paper P by applying a transfer potential between the intermediate transfer belt 30 and the paper P. The sheet P on which the toner image is transferred is conveyed from the secondary transfer unit 50 to the fixing device 60, and the toner image transferred onto the sheet is fixed. In this way, an image is formed on the paper. The sheet on which the image is formed is discharged to the outside of the image forming apparatus 1 by the discharge roll 86. The toner remaining on the intermediate transfer belt 30 after the transfer by the secondary transfer device 50 is removed by the belt cleaner 70.

[Developer]
FIG. 2 is a plan view of the developing device shown in FIG. FIG. 3 is a side view of the developing device, and FIG. 4 is a longitudinal sectional view of the developing device. Although the developing device 14Y for yellow is shown in the drawing, the developing devices 14M to 14K for other colors also have the same structure as the developing device 14Y.

  The developing device 14Y includes a developer container 140, a developer roll 141, a first stirring and conveying member 142, a second stirring and conveying member 143, a stirring magnet 144, and a transfer mechanism 145. FIG. 2 shows a state where the cover of the developer container 140 and the developing roll 141 are removed, and the position of the developer container 140 is indicated by a broken line.

  The developer container 140 contains a developer. The interior of the developer container 140 is partitioned into a first storage chamber 140a and a second storage chamber 140b by a partition wall 1401 extending in parallel with the developing roll 141. The first storage chamber 140a is adjacent to the developing roll 141, and the second storage chamber 140b is disposed on the opposite side of the developing roll 141 with the first storage chamber 140a interposed therebetween. A first agitation transport member 142 is disposed in the first storage chamber 140a, and a second agitation transport member 143 is disposed in the second storage chamber 140b.

  The two agitating / conveying members 142 and 143 extend in the front-rear direction DE in the image forming apparatus 1, that is, in the extending direction in which the developing roll 141 extends. The agitating / conveying members 142 and 143 include rotating shafts 1421 and 1431 extending in parallel with the developing roll 141 and spiral spiral blades 1422 and 1432 provided around the rotating shafts 1421 and 1431, respectively. The spiral blade 1432 of the second stirring and conveying member 143 is formed of a magnetic material. Specifically, the rotating shafts 1421, 1431 and the spiral blades 1422, 1432 of the two agitating and conveying members 142, 143 are formed of a magnetic material. Here, the magnetic material is a material that generates an attractive force between the magnet and the magnet, and is a material having paramagnetism or ferromagnetism. The magnetic material is, for example, iron or an iron alloy.

  The first stirring / conveying member 142 and the second stirring / conveying member 143 are rotatably supported at both end portions of the respective rotating shafts 1421, 1431. Here, the second stirring / conveying member 143 is disposed so as to have a gap G that allows the developer to pass between the outer peripheral edge of the spiral blade 1432 and the inner wall 1403 of the second storage chamber 140b. . The gap G is narrowed to such an extent that the toner of the developer passing therethrough and the magnetic carrier come into contact with each other and the charge amount is maximized. The dimension of the gap G is 1 mm or less. One ends of the rotating shafts 1421 and 1431 are connected to a gear 146 that transmits a driving force from a motor (not shown). The developing roll 141 and the two agitating / conveying members 142 and 143 are driven by a motor (not shown) to rotate.

  The first agitating and conveying member 142 conveys the developer in the first storage chamber 140a in the first conveying direction D by rotating around the axis of the rotating shaft 1421. The second agitating / conveying member 143 rotates in the same direction as the first agitating / conveying member 142 around the rotation shaft 1431, thereby causing the developer in the second storage chamber 140 b to be in the second conveying direction opposite to the first conveying direction. Transport in direction E. The conveyance speed at which the first agitation conveyance member 142 and the second agitation conveyance member 143 convey the developer is the product of the rotation speed of the first agitation conveyance member 142 and the second agitation conveyance member 143 and the pitch of the spiral blades 1422 and 1432. Based on. Discharge windows 1401a and 1401b are provided on the partition wall 1401 that partitions the first storage chamber 140a and the second storage chamber 140b, and the developer stored in the developer container 140 passes through the discharge windows 1401a and 1401b. Then, it circulates around the partition wall 1401.

  The developing roll 141 conveys the developer containing toner and magnetic carrier from the first storage chamber 140a to the surface of the photoreceptor 11Y (see FIG. 1). The developing roll 141 has a cylindrical shape, and a magnet 1411 is disposed inside the developing roll 141. The magnet 1411 is fixed to the developer container 140, and has a pickup magnetic pole for attracting the magnetic carrier to which the toner particles are adhered to the developing roll 141, and a magnetic pole for causing the developer to stand up in the development area. Further, a voltage is applied to the developing roll 141 so that an electrostatic force acts on the toner particles on the developing roll 141.

  A cylindrical developing roll 141 having a magnet roll provided therein holds the developer on its surface and conveys the developer to the surface of the photoreceptor 11Y, and is an example of the developer conveying section referred to in the present invention. It corresponds to. The photoconductor 11Y corresponds to an example of a developing target according to the present invention. Note that the toner and magnetic carrier that are not attracted to the photoreceptor 11Y return to the first storage chamber 140a. Further, an amount of toner corresponding to the consumed amount is supplied from the toner cartridge 18Y to the developer container 140.

  The toner and magnetic carrier contained in the developer are agitated by the first agitating and conveying member 142 and the second agitating and conveying member 143, and are thus charged with opposite polarities. Here, when the charge amount of the toner is insufficient, there is a possibility that the toner does not adhere to the electrostatic latent image on the photoreceptor 11Y and becomes a cloud. Further, there is a possibility that the toner floating as a cloud adheres to the background portion of the electrostatic latent image on the photoconductor 11Y and fogging occurs. The stirring magnet 144 and the transfer mechanism 145 in this embodiment increase the amount of developer stirring.

[Stirring magnet]
The stirring magnet 144 is a permanent magnet that is disposed to face the outer wall 1402 of the developer container 140 that extends in the front-rear direction DE. The stirring magnet 144 is connected to a spinning motor 1441 and rotates around an axis that intersects the surface of the outer wall 1402. More specifically, the stirring magnet 144 rotates around the axis. The stirring magnet 144 corresponds to an example of a magnet according to the present invention.

  The transfer mechanism 145 includes a lead screw 1451, a slider 1452, and a slide motor 1453. The lead screw 1451 is a round bar extending along the outer wall 1402 of the developer container 140, and a screw is formed on the peripheral surface. The lead screw 1451 extends in parallel with the rotation shafts of the first stirring / conveying member 142 and the second stirring / conveying member 143, and is rotatably supported by the developer container 140. The slider 1452 is threadedly engaged with the lead screw 1451 and is supported by the lead screw 1451. More specifically, the slider 1452 is provided with a hole in which a female screw is formed, and the lead screw 1451 passes through this hole. A spin motor 1441 to which a stirring magnet 144 is attached is fixed to the slider 1452. The slide motor 1453 rotates and drives the lead screw 1451 according to the control of the control unit 1A (see FIG. 1). The slide motor 1453 rotates the lead screw 1451 in the forward and reverse directions to reciprocate the slider 1452. Accordingly, the slider 1452 transfers the stirring magnet 144 along the outer wall 1402 of the developer container 140 in the front-rear direction DE in which the second stirring and conveying member 143 extends. The stirring magnet 144 reciprocates substantially over the entire length of the second stirring and conveying member 143.

  The spin motor 1441 changes the transfer speed of the stirring magnet 144 by changing the rotation speed according to the direction of movement. The agitation magnet 144 is transferred so that the relative speed with respect to the developer conveyance speed by the rotation of the second agitation conveyance member 143 is the same in both directions of reciprocation. That is, when the conveyance speed by the second agitating / conveying member 143 is V, the stirring magnet 144 is moved in the direction of conveyance by the second agitating / conveying member 143, that is, when it is transferred in the second conveying direction E (forward direction). V + α. Further, the speed when the agitating magnet 144 is transferred in the direction opposite to the conveying direction by the second agitating and conveying member 143, that is, in the first conveying direction D (reverse direction) is defined as V−α. For example, when the transport speed by the second stirring transport member 143 is 25 mm / s, the forward speed of the stirring magnet 144 is 75 mm / s, and the reverse speed is 25 mm / s. In this case, the relative speed α with respect to the conveyance of the second stirring / conveying member 143 is 50 mm / s in both the forward and reverse directions.

  The stirring magnet 144 facing the outer wall 1402 of the developer container 140 attracts the developer in the developer container 140 by magnetic force. In the inner wall 1403 of the developer container 140, at a position corresponding to the stirring magnet 144, the magnetic carrier is in a spiked state due to the magnetic force of the stirring magnet 144.

  When the agitating magnet 144 is transferred, the agitating magnet 144 moves with the magnetic carrier gathered in the rising state in the developer container 140. Since the stirring magnet 144 is transferred at the predetermined relative speed described above with respect to the transport speed of the second stirring and transporting member 143, the spikes of the magnetic carrier brought about by the stirring magnet 144 are second stirrer. The carrier collides with the spiral blade 1432 of the conveying member 143 and collapses, and the magnetic carrier passes through the gap G between the spiral blade 1432 and the inner wall 1403 while enclosing toner in the vicinity. At this time, the magnetic carrier and the toner are agitated and charged with opposite polarities.

  When the stirring magnet 144 is transferred in the front-rear direction DE, the magnetic carrier and toner in the developer container 140 are applied to the spiral blade 1432 and the gap G is forcibly passed. For this reason, the friction between the magnetic carrier and the toner is large and the charge amount of the magnetic carrier and the toner is increased as compared with the case where the stirring magnet rotates around the axis extending in the front-rear direction.

  The stirring magnet 144 is connected to a spinning motor 1441 and rotates around an axis that intersects the surface of the outer wall 1402. Therefore, the magnetic carrier attracted to the stirring magnet 144 also moves so as to rotate about the same axis. This further agitates the magnetic carrier with nearby toner. Therefore, the charge amount is increased as compared with the case where the stirring magnet 144 does not rotate.

  Further, since the spiral blade 1432 is made of a magnetic material, it becomes magnetized as the stirring magnet 144 approaches. For this reason, the magnetic carrier receives an attractive force from the spiral blade 1432. In the vicinity of the gap G, strong friction is generated by entraining toner between the magnetic carrier drawn by the spiral blade 1432 and the magnetic carrier drawn by the stirring magnet 144. Therefore, the amount of charge increases compared to the case where the spiral blade 1432 is not formed of a magnetic material.

[Example]
EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

  First, in the developing device described in the above-described embodiment, the first stirring / conveying member 142, the second stirring / conveying member 143, and the transfer mechanism 145 are operated while the developing roll 141 is stopped, and the charge amount of the toner is measured. . Note that the spinning motor 1441 was stopped. In addition, the conveyance speed by the 1st stirring conveyance member 142 and the 2nd stirring conveyance member 143 was 25 mm / s. The transfer speed of the stirring magnet 144 by the transfer mechanism 145 was 75 mm / s in the forward direction and 25 mm / s in the reverse direction. In this case, the relative speed of the stirring magnet 144 with respect to the transport of the second stirring transport member 143 is 50 mm / s in both the forward and reverse directions.

  Here, a plurality of kinds of gaps G between the inner wall 1403 of the second storage chamber 140b and the spiral blade 1432 are 0.2 mm, 0.4 mm, 0.6 mm, 1 mm, 1.5 mm, 2 mm, and 3 mm. The charge amount was measured for each of the second stirring and conveying members. For the types of the stirring magnet 144, the charge amount was measured for each of 2200 gauss, 3200 gauss, and 4200 gauss.

In measuring the charge amount of the toner, after the developing device is operated, a part of the developer is taken out, and the charge amount TV [μC / g] per unit mass and the toner ratio Tn in the developer by the charge measuring device. Measure. Next, the toner charge amount AT is expressed by the following formula: AT = (toner ratio Tn * 100 + α) * TV
Calculated by Here, α is a coefficient for correcting the deviation of the measured value of the charge amount TV that differs for each type of developer. In this embodiment, the calculation is performed with α = 4. The following table shows the toner charge amount. FIG. 5 is a graph showing the toner charge amount.

  As shown in the table, if the size of the gap G between the inner wall 1403 and the spiral blade 1432 is the same, the toner charge amount is larger when the magnetic force of the stirring magnet 144 is stronger. Further, the toner charge amount tends to increase as the size of the gap G decreases. However, at any magnetic force, when the size of the gap G is 1 mm or less, the increase in the toner charge amount is saturated. That is, at any magnetic force, the size of the gap G is 1 mm or less, and the toner charge amount becomes the maximum value.

  In particular, when the magnetic force of the stirring magnet 144 is 4200 gauss or more, the size of the gap G is 1 mm or less, and the toner charge amount is 450 or more.

[Image evaluation]
Next, in the image forming apparatus having the configuration described in the above embodiment, the image quality when an image was formed on paper was evaluated. Further, the toner charge amount in the developer in the developing device was measured. In the evaluation of the image quality, the degree of toner adhesion, that is, the degree of “fogging” was inspected on the background portion of the paper where no toner originally exists.

  Regarding the developing device, when the magnetic force of the stirring magnet is 4200 gauss, the gap G between the inner wall and the spiral blade is 1 mm, 1.5 mm, 3 mm, 0.5 mm, and 0.2 m. In the case of 1 to 5 and the magnetic force is 3200 gauss, the gaps G between the inner wall and the spiral blade were 1 mm and 1.5 mm, and Examples 6 and 7 were used. Further, Comparative Example 1 (0 Gauss) from which the stirring magnet was removed was also evaluated.

  The following table shows the evaluation results of toner charge amount and “fogging”.

  As shown in the table, in Examples 1 to 5 having the stirring magnet, a higher toner charge amount was obtained as compared with Comparative Example 1 in which the stirring magnet was removed. Further, in Comparative Example 1, fog that was a practical problem in light of the image quality standards of the image forming apparatus was recognized, but in Examples 1 to 5, the fog that was a practical problem was not visually recognized. In particular, in Examples 1, 4 and 5, where the magnetic force of the stirring magnet 144 is 4200 Gauss or more and the size of the gap G is 1 mm or less, the toner charge amount is 450, and the fog is It was not visually recognized.

  In the embodiment described above, a permanent magnet is shown as an example of the stirring magnet referred to in the present invention. However, the present invention is not limited to this, and the stirring magnet may be, for example, an electromagnet.

  In the above-described embodiment, a tandem type color printer is shown as an example of the image forming apparatus according to the present invention. However, the image forming apparatus according to the present invention is not limited to this, for example, a monochrome printer without an intermediate transfer belt. A dedicated printer may be used.

  In the above-described embodiment, a printer is shown as an example of the image forming apparatus according to the present invention. However, the image forming apparatus according to the present invention is not limited to a printer, for example, based on data read by an image reading apparatus. It may be a copier or a facsimile machine that forms an image.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10Y, 10M, 10C, 10K Image forming part 11Y Photoconductor 14Y Developing apparatus 140 Developer container 1402 Outer wall 1403 Inner wall 141 Developing roll 142,143 Stirring conveyance member 1431 Rotating shaft 1432 Blade 144 Stirring magnet 1441 Spin motor 145 Transfer mechanism G Gap

Claims (4)

A developer container containing a developer containing toner and a magnetic material;
A rotating shaft and a spiral blade provided around the rotating shaft, and disposed in the developer container with a gap between the inner wall of the developer container and the blade, and rotated. A conveying member for conveying the developer in the developer container in the extending direction of the rotating shaft while stirring the developer in the developer container;
A magnet that is disposed opposite to an outer wall of the developer container that extends in the extending direction, and that attracts the developer in the developer container with a magnetic force;
A developing device comprising: a transfer mechanism that transfers the magnet along the outer wall in the extending direction.   The developing device according to claim 1, wherein the magnet rotates about an axis intersecting with the surface of the outer wall.   3. The developing device according to claim 1, wherein the blade is made of a magnetic material. A developing target on which an electrostatic latent image is formed on the surface and the electrostatic latent image is developed with toner;
A developing device for developing the object to be developed with toner,
A developer container containing a developer containing toner and a magnetic material;
A rotating shaft and a spiral blade provided around the rotating shaft, and disposed in the developer container with a gap between the inner wall of the developer container and the blade, and rotated. A conveying member for conveying the developer in the developer container in the extending direction of the rotating shaft while stirring the developer in the developer container;
A magnet that is disposed opposite to an outer wall of the developer container that extends in the extending direction, and that attracts the developer in the developer container with a magnetic force;
An image forming apparatus comprising: a transfer mechanism configured to transfer the magnet along the outer wall in the extending direction.

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