JPH10333438A - Electrostatic latent image developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high developing performance, and also, to prevent the occurrence of toner milt-sticking and the damage of a sleeve member by combining a 1st developer apply means constituted of a rotary sleeve member and a permanent magnet which is rotated in a direction reverse to that of the rotary sleeve member and a 2nd developer apply means constituted of a rotary sleeve member and a stationary permanent magnet. SOLUTION: Due to a magnetic field formed by a 2nd magnet means constituting the 2nd developer apply means 31, the developer 100 passing through a developing area 6 while being held on the circumferential surface of the 1st sleeve member 21 of the 1st developer apply means 20 is transferred to the circumferential surface of the 2nd sleeve member 31. The developer 100 held on the circumferential surface of the 2nd sleeve member 31 of the 2nd developer apply means 31 is separated resulting from non-existence of a magnetic attraction force in a developer peeling area 35 formed in the 2nd apply means 31, then a peeling means such as a cleaning blade, etc., for separating the developer 100 is unnecessitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image developing apparatus for developing an electrostatic latent image into a toner image in an image forming machine such as an electrostatic copying machine or a laser printer. The present invention relates to an electrostatic latent image developing device including a plurality of developer applying units.

[0002]

2. Description of the Related Art In an image forming machine such as an electrostatic copying machine or a laser printer, as is well known, an electrostatic latent image is formed on an image carrier, and this electrostatic latent image is developed into a toner image. ing. Such development is accomplished by applying developer by means of developer application means on the image carrier as the image carrier is moved through the development zone. Japanese Patent Application Laid-Open No. 60-68364 discloses an electrostatic latent image developing apparatus having two developer applying means for reliably applying a developer to an image carrier in response to an increase in image forming speed. And JP-A-3-31876. The electrostatic latent image developing devices disclosed in these publications include a first developer application unit disposed in a development area so as to face an image carrier, and an image bearing device for the first developer application unit. A second developer application unit disposed downstream of the body in the moving direction of the body, that is, below the first developer application unit and facing the image carrier.
A developer composed of carrier particles and toner is applied to the image carrier by the individual developer application means, and the electrostatic latent image is developed into a toner image.

More specifically, the first developer applying means in the electrostatic latent image developing device includes a first sleeve member driven to rotate and a stationary magnet means disposed in the first sleeve member. It is composed of Further, the second developer applying unit is also similar to the first developer applying unit,
It comprises a second sleeve member which is driven to rotate, and stationary magnet means disposed in the second sleeve member. The surface of the first sleeve member is moved in a direction opposite to the movement of the image carrier in the development area,
The surface of the second sleeve member is moved in the forward direction with respect to the movement of the image carrier in the development area. Such an electrostatic latent image developing device is also provided with a developer stirring / conveying mechanism, and the developer agitated by the developer stirring / conveying mechanism constitutes the second developer applying unit. A part of the developer which is magnetically attracted and held on the surface of the sleeve member and then held on the surface of the second sleeve member is applied to the surface of the first sleeve member which constitutes the first developer applying means. It is transported, magnetically attracted and held there, and applied on the image carrier in the development zone. Further, the developer that has been suctioned and held on the surface of the second sleeve member without being transferred to the surface of the first developing sleeve member is also applied to the image carrier in the development area.

[0004] On the other hand, as a developer capable of improving the developing ability and obtaining a high-quality image, a developer applying means is disposed inside the rotary sleeve member and rotated in a direction opposite to the rotary sleeve member. 2. Description of the Related Art An electrostatic latent image developing device configured with a driven rotating magnet and generating a so-called oscillating magnetic field in a developing area has been put to practical use. In this type of electrostatic latent image developing apparatus, the developer magnetically adsorbed on the peripheral surface of the sleeve member bends around the developing region while behaving in a manner of bouncing due to a change in the magnetic field caused by the rotating permanent magnet. Since the image passes through, there is a feature that a high quality image can be obtained with high developing ability.

[0005]

Thus, in an electrostatic latent image developing apparatus provided with developer applying means configured to rotate a permanent magnet in a direction opposite to that of a rotating sleeve member,
Due to the rotation of the permanent magnet, it is not possible to provide a developer peeling area that passes through the developing area and releases the magnetically attracted developer on the peripheral surface of the sleeve member. For this reason,
This type of electrostatic latent image developing device is provided with a cleaning blade for releasing the developer magnetically attracted to the peripheral surface of the sleeve member through the developing area. However, since the cleaning blade is configured to contact the peripheral surface of the sleeve member to scrape off the developer, there are problems such as toner fusion or damage to the peripheral surface of the sleeve member.

[0006] The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is to take advantage of the characteristics of a developer applying means configured to rotate a permanent magnet in a direction opposite to that of a rotating sleeve member. An object of the present invention is to provide an electrostatic latent image developing device that can obtain high developing ability and can prevent fusion of toner and damage to a sleeve member.

[0007]

According to the present invention, there is provided a developer applying means comprising a rotating sleeve member and a permanent magnet disposed in the rotating sleeve member and driven to rotate in a direction opposite to the rotating sleeve member. An electrostatic latent image developing apparatus capable of achieving the above-mentioned technical problem by utilizing both features by combining a developer applying unit including a sleeve member and a stationary permanent magnet disposed in the rotating sleeve member. I will provide a.

That is, according to the present invention, an electrostatic latent image formed on an image carrier which is moved through a development area is formed on the image carrier in the development area by development of carrier particles and toner. An electrostatic latent image developing device for applying a developing agent to develop a toner image, a developing housing for housing the developing agent, the developing housing being disposed in the developing housing, and adsorbing and holding the developing agent on a peripheral surface thereof. A first developer application unit that conveys the first carrier to the area, and a first developer application unit that is disposed downstream of the image carrier in the moving direction of the image carrier with respect to the first developer application unit, and that faces the first developer application unit. A second developer application unit that adsorbs and holds the developer held on the peripheral surface of the first developer application unit on the peripheral surface of the first developer application unit and transports the developer to the development region,
The first developer applying unit includes a first sleeve member that is rotationally driven to move in a forward direction with respect to a moving direction of the image carrier in the development area, and a first sleeve member that is provided inside the first sleeve member. The first sleeve member and first magnet means rotatably driven in the opposite direction, and the second developer applying means includes a moving direction of the image carrier in the developing area. A second sleeve member rotatably driven to move in a forward direction with respect to the second sleeve member, and a second magnet means disposed in the second sleeve member and fixedly fixed at a predetermined position. The second magnet means forms a repulsive magnetic field area at a position facing the first developer applying means, and has a developer peeling area substantially free of magnetic attraction on the lower side. An electrostatic latent image developing device is provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an electrostatic latent image developing device constructed in accordance with the present invention will be described below in further detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of an electrostatic latent image developing device constructed according to the present invention, together with a part of a rotating drum 2 constituting an image carrier. Rotating drum 2
Is provided with an appropriate electrostatic photoreceptor on its peripheral surface, and is rotated in a direction indicated by an arrow 4 in FIG. . The developing zone 6 extends in the vertical direction in the direction of movement of the peripheral surface of the rotary drum 2 (therefore, the direction of movement of the image carrier).
The developing surface 6 is moved from the upper side to the lower side on the peripheral surface of the rotating drum 2 which is rotated in the direction shown by. On the upstream side of the developing area 6, an electrostatic latent image is formed on the peripheral surface of the rotating drum 2 by a suitable electrostatic latent image forming means known per se. In the developing area 6, the electrostatic latent image formed on the peripheral surface of the rotary drum 2 is developed into a toner image by an electrostatic latent image developing device generally designated by the numeral 8 according to the present invention. The toner image thus developed is transferred to a transfer member such as plain paper by a transfer unit on the downstream side of the development area 6. Then, the toner image transferred to the transfer member is heat-fixed by a fixing unit to obtain a copy or printed matter.

Referring to FIGS. 1 and 2, the electrostatic latent image developing device 8 includes a developing housing 10. The developing housing 10, which can be formed from a suitable synthetic resin, includes a front end wall 16 and a rear end wall 18 along with a bottom wall 12 and a rear wall 14 extending substantially vertically upward from the rear edge of the bottom wall 12. I have. A cover member 19 formed of a synthetic resin and covering the upper surface thereof is provided on the developing housing 10 configured as described above.

At the forefront of the developing housing 10 (the leftmost part in FIG. 1, and the uppermost part in FIG. 2), the first developer applying means 20 and the lower part of the first developer applying means 20 are arranged. Second developer applying means 30 is provided.
The first developer applying means 20 extends substantially horizontally in the developing area 6 in the width direction (the direction perpendicular to the paper surface in FIG. 1 and the left-right direction in FIG. 2) and is disposed parallel to the rotating drum 2. The first sleeve member 21 is provided with first magnet means 22 disposed in the first sleeve member 21. The first sleeve member 21 is formed of a non-magnetic material such as aluminum and the like.
It is rotatably mounted on. The first magnet means 22
Are constituted by stationary permanent magnets, and N poles and S poles are alternately formed on the outer peripheral surface thereof. The first magnet means 22 configured as described above is used for the first sleeve member 21.
And is rotatably mounted on the developing housing 10 and the first sleeve member 21. As shown in FIG. 2, the rotation shaft 23 to which the first sleeve member 21 is fixed is projected rearward through the rear end wall 18 of the developing housing 10. An input gear (not shown) is fixed to the protruding end of the rotating shaft 23,
The input gear is operatively connected to a rotary drive source (not shown), which may be an electric motor, via a suitable transmission gear (not shown). The rotating shaft 24 to which the first magnet means 22 is fixed is connected to the front end wall 16 of the developing housing 10.
And project forward. This rotating shaft 2
An input gear (not shown) is fixed to the protruding end portion 4 and the input gear is operatively connected to a rotary drive source (not shown) via a suitable transmission gear (not shown). I have. The first developer applying means 20 thus configured
The first sleeve member 21 moves in the direction indicated by an arrow 25 in FIG.
The first magnet means 22 is driven to rotate in a direction indicated by an arrow 25 in FIG. 1, that is, in a direction opposite to the rotation direction of the first sleeve member 21. Can be

The second developer application means 30 is located downstream of the rotary drum 2 with respect to the first developer application means 20 in the developing zone 6 (in FIG. 1, the first developer application means). 20 below). This second
A second sleeve member extending substantially horizontally in the width direction (the direction perpendicular to the plane of FIG. 1 and the left-right direction in FIG. 2) and disposed in parallel with the rotary drum 2 31 and a second magnet means 32 disposed in the second sleeve member 31. The second sleeve member 31 is formed of a non-magnetic material such as aluminum, and is rotatably mounted on the developing housing 10. The second magnet means 32 is constituted by a stationary permanent magnet, and is fixed at a predetermined position in the second sleeve member 31. The cross-sectional shape of the stationary permanent magnet constituting the second magnet means 32 is not circular, and there is a fan-shaped missing portion 33 on the lower side in FIG. As shown in FIG. 1, an N pole and an S pole are formed on the outer peripheral surface of the stationary permanent magnet as the second magnet means 32 configured as described above. The N pole and the N pole are magnetized adjacent to each other on the outer peripheral surface of the magnet means 32 at a position facing the first developer applying means 20 to form a repulsive magnetic field area 34. Further, due to the presence of the above-mentioned missing portion 33 of the stationary permanent magnet constituting the magnet means 32, the second sleeve member 31 shown in FIG.
In the lower part, there is substantially no magnetic attraction force for attracting the developer to the peripheral surface of the second sleeve member 31 (including the case where the magnetic attraction force is slight if any). A peeling area 35 is defined. In the illustrated embodiment, an example is shown in which the developer-peeled area 35 having substantially no magnetic attraction force is formed by providing the stationary permanent magnet with a sector-shaped defect, but the stationary permanent magnet having a circular cross-sectional shape is shown. N of the magnetic pole magnetized in the developer separation area at
The pole and the N pole or the S pole and the S pole may be adjacent to each other to form a repulsive magnetic field. As shown in FIG. 2, the rotation shaft 36 to which the second sleeve member 31 is fixed projects through the rear end wall 18 of the developing housing 10 and projects rearward. An input gear (not shown) is fixed to the protruding end of the rotating shaft 36, and the input gear is fixed to the rotating shaft 23 of the first developer applying means 20 (not shown). Transmission connection. The second sleeve member 31 of the second developer applying unit 30 thus configured
Is driven to rotate in the direction indicated by the arrow 37 in FIG. 1, that is, in the developing area 6 in the forward direction with respect to the movement of the rotary drum 2.

Continuing the description with reference to FIG. 1, the electrostatic latent image developing device 8 is further provided with a head cutting means 40. In the illustrated embodiment, the ear cutting means 40 includes a second
Is formed by an ear-cutting plate 41 extending in the width direction (the direction perpendicular to the paper surface in FIG. 1) along the developer application means 30 of FIG. In the illustrated embodiment, the cutting board 41 is made of non-magnetic stainless steel, and the rotation direction of the second sleeve member 31 constituting the second developer applying unit 30 (the direction indicated by the arrow 37). And a front edge close to the peripheral surface of the second sleeve member 31 on the upstream side of the developing region 6 and on the upstream side of the repulsive magnetic field region 34. A gap G1 between the leading edge of the ear cutting plate 41 and the peripheral surface of the second sleeve member 31 is set to about 1 to 2 mm in the illustrated embodiment.

A developer stirring / conveying mechanism 50 is provided behind the second developer applying means 30. In the illustrated embodiment, the downstream transport path 5 is
1 and a midstream transport path 52 and an upstream transport path 53 are provided in parallel in the front-rear direction (the left-right direction in FIG. 1 and the up-down direction in FIG. 2).

A downstream partitioning means 54 is provided between the downstream transport path 51 and the midstream transport path 52. The downstream partition means 54 includes a pair of partition walls 541 and 542, and is fixed to the bottom wall 12 of the developing housing 10 by a plurality of screws. The pair of partition walls 541, 54
As shown in FIG. 1, both sides of each lower end portion are formed in a concave arc shape. In addition, a pair of partition walls 541 and 542
As shown in FIG. 2, opposed inner ends are provided at an interval from each other. Therefore, a developer transfer port 543 is formed at the center of the downstream partition means 54. Further, the outer ends of the pair of partition walls 541 and 542 and the developing housing 1
2, a predetermined interval is provided between the front end wall 16 and the rear end wall 18 as shown in FIG.
4, 545 are formed.

An upstream partitioning means 55 is provided between the intermediate flow path 52 and the upstream path 53. The upstream partition means 55 comprises a pair of partition walls 551 and 552 in the illustrated embodiment.
The bottom wall 12 is fixed by a plurality of screws.
As shown in FIG. 1, both side surfaces of the lower end of the pair of partition walls 551 and 552 are formed in a concave arc shape. Also,
As shown in FIG. 2, the pair of partition walls 551 and 552 have opposing inner ends spaced apart from each other.
A developer transfer port 553 is formed at the center of the upstream partitioning means 55. Further, a predetermined interval is provided between each outer end of the pair of partition walls 551 and 552 and the front end wall 16 and the rear end wall 18 of the developing housing 10 as shown in FIG. Developer transfer ports 554 and 555 are formed on both sides in the width direction of the partitioning means 55, respectively.

The downstream conveying path 51 is provided with downstream stirring and conveying means 56 as first stirring and conveying means.
The downstream stirring and conveying means 56 has a rotating shaft 561 rotatably mounted between both end walls 16 and 18 of the developing housing 10 as shown in FIG. This rotating shaft 561
A pair of spiral blades 562 and 563 are formed at an interval in the axial direction, that is, the width direction. Spiral blade 562
And the spiral blade 563 are formed so that the winding directions are opposite to each other. The outer diameter of the spiral blade 562 is the same as the outer diameter of the spiral blade 563. It is preferable that the widthwise inner ends of the spiral blades 562 and 563 correspond to substantially the center of the developer transfer port 543 formed at the center of the downstream partitioning means 54. The outer ends in the width direction of the spiral blades 562 and 563 are positioned substantially corresponding to the widthwise middle of the developer transfer ports 544 and 545 formed on both sides in the width direction of the downstream partitioning means 54. The spiral blade 5 is provided at both ends of the rotating shaft 561.
Auxiliary spiral blades 564 and 565 are formed opposite to 62 and 563, respectively. The auxiliary spiral blades 564 and 565 have the same outer diameter as the outer diameters of the spiral blades 562 and 563, and are formed over an angle range of about 360 degrees. Note that the winding directions of the auxiliary spiral blades 564 and 565 are opposite to the winding directions of the spiral blades 562 and 563 facing each other.

In the medium flow path 52, there is provided a medium flow stirring and conveying means 57 as a second stirring and conveying means.
The midstream stirring and conveying means 57 includes a rotating shaft 5 rotatably mounted between both end walls 16 and 18 of the developing housing 10.
71. The rotating shaft 571 has a pair of spiral blades 572 and 57 spaced apart in the axial direction, that is, the width direction.
3 are formed. Spiral blade 572 and spiral blade 573
Are formed in mutually opposite winding directions. Spiral blade 5
The outer diameter of the spiral blade 72 is the same as the outer diameter of the spiral blade 573, and
2 and 563 are configured to have a larger diameter than the outer diameter. The widthwise inner ends of the spiral blades 572 and 573 are connected to the developer transfer port 5 provided at the center of the downstream partitioning means 54.
43, the outer ends of the spiral blades 572 and 573 in the width direction are provided at both sides of the downstream partitioning means 54 in the width direction.
4, 545 are located substantially at the center in the width direction or slightly outside. The rotating shaft 571 is further provided with an inclined elliptical plate 574 at the center in the width direction. The widthwise dimension of the inclined elliptical plate 574 is substantially the same as the widthwise dimension of the developer transfer port 543 provided at the center of the downstream partitioning means 54. The inclined elliptical plate 574 has a circular shape in a side view.
2 and 573 have substantially the same outer diameter.

The upstream conveying path 53 is provided with an upstream stirring and conveying means 58 as a third stirring and conveying means.
The upstream stirring and conveying means 58 includes a rotating shaft 5 rotatably mounted between both end walls 16 and 18 of the developing housing 10.
81. The rotating shaft 581 has a pair of spiral blades 582 and 58 spaced apart in the axial direction, that is, the width direction.
3 are formed. Spiral blade 582 and spiral blade 583
Are formed in mutually opposite winding directions. Spiral blade 5
The outer diameter of the spiral blade 582 is the same as the outer diameter of the spiral blade 582, and
2 and 573 have the same outer diameter. The inner ends of the spiral blades 582 and 583 in the width direction are located slightly outside the developer transfer port 553 provided at the center in the width direction of the upstream partition wall means 55, and the spiral blades 582 Each of the widthwise outer ends of the upstream and downstream members 583 and 583 is positioned substantially corresponding to the widthwise middle of the developer transfer ports 554 and 555 provided at both widthwise ends of the upstream partition wall means 55. Auxiliary spiral blades 584 and 585 are formed at both ends of the rotating shaft 581 so as to be opposed to the spiral blades 582 and 583, respectively. The outer diameters of the auxiliary spiral blades 584 and 585 are the same as the outer diameters of the spiral blades 582 and 583. The auxiliary spiral blades 584 and 5
85 is formed over an angle range of approximately 360 degrees, and its winding direction is opposite to the winding direction of the opposing spiral blades 582 and 583, respectively. Rotating shaft 581
Is further provided with an inclined elliptical plate 586 at the center in the width direction. The width dimension of the inclined elliptical plate 586 is
The widthwise dimension of the developer transfer port 553 provided at the center in the width direction of the upstream partition means 55 is substantially the same. The inclined elliptical plate 586 has a circular shape in a side view, and the diameter of the circular shape is substantially the same as the outer diameter of the spiral blades 582 and 583.

The rotary shaft 56 of the downstream stirring and conveying means 56
1. Each of the rotating shaft 571 of the middle-flow stirring and conveying means 57 and the rotating shaft 581 of the upstream stirring and conveying means 58 is projected rearward through the rear end wall 18 of the developing housing 10 and each of these rotating shafts Input gears (not shown) are fixed to the rear ends of 561, 571, and 581, respectively, and these input gears are suitably driven gears (not shown).
Through a rotary drive source (not shown). The downstream stirring / transporting means 56, the midstream stirring / transporting means 57, and the upstream stirring / transporting means 58 thus configured are
Each of them is driven to rotate in the directions indicated by arrows 560, 570 and 580 in FIG.

The downstream stirring / transporting means 56, the midstream stirring / transporting means 57 and the upstream stirring / transporting means 5 constructed as described above.
8 will be described. The transfer capacity of the middle-flow stirring transfer means 57 is set to be larger than the transfer capacity of each of the downstream stirring transfer means 56 and the upstream stirring transfer means 58. The transport of the developer from both ends in the axial direction to the central portion in the axial direction and the transport of the developer from the central portion in the axial direction to both ends in the axial direction are substantially balanced, so that the developer is uniformly present throughout the entire axial direction. In order to make the
It is desirable that the transfer capacity of 7 is substantially equal to the sum of the transfer capacity of the downstream stirring transfer means 56 and the transfer capacity of the upstream stirring transfer means 58. It is desirable that the transfer capacity of the downstream stirring and conveying means 56 is set to be larger than that of the upstream stirring and conveying means 58.
Is 1.2 times the transport capacity of the upstream stirring transport means 58.
It is preferably about 2.5 times. The developer transfer capacity of each of the downstream stirring transfer means 56, the middle flow stirring transfer means 57, and the upstream stirring transfer means 58 is set as required by appropriately setting the rotation speed, pitch, and outer diameter of each spiral blade. can do. In the illustrated embodiment, the number of rotations per unit time of the downstream stirring / conveying means 56 and the number of rotations per unit time of the upstream stirring / conveying means 58 are the same. The number of rotations per unit time is set large. Spiral blades 562 and 56 of downstream stirring and conveying means 56
3 is larger than the pitch of the spiral blades 582 and 583 of the upstream stirring and conveying means 58,
The pitches of the spiral blades 572 and 573 are further larger than the spiral blades 562 and 563 of the downstream stirring and conveying means 56.

Referring to FIGS. 1 and 2, a circular opening 12a is formed in a predetermined portion of the bottom wall 12 of the developing housing 10 which faces the middle flow path 52. A detector 60 for detecting the toner concentration in the developer 100 including the carrier particles and the toner contained in the developing housing 10 is provided in the opening 12a.
Are arranged. The detector 60 is exposed in the developing housing 10 through the opening 12a, and detects the toner density in the developer 100 by detecting the magnetic permeability of the developer 100 present on the upper surface thereof. A known form may be used. The electrostatic latent image developing device 8 further includes a developer 100 detected by the detector 60.
There is also provided a toner supply means which is operated in accordance with the toner concentration in the toner. The toner supply means includes a supply pipe 62 provided on the cover member 19 of the developing housing 10. One end of the feed pipe 62 is located above the center in the width direction of the upstream transport path 53, and a feed port 62 a communicating with the inside of the developing housing 10 is formed on the lower surface thereof. The other end of the feed pipe 62 extending from the one end to the front end in the width direction is communicated with a toner container (not shown), and the inside of the feed pipe 62 can be formed by a spiral blade. Means (not shown) are provided. When the toner concentration in the developer 100 detected by the detector 60 becomes equal to or lower than a predetermined value, the toner conveying means in the feeding pipe 62 is operated, and the toner is conveyed from the toner container through the feeding pipe 62, and the toner is conveyed. The spiral blades 582 and 5 of the upstream stirring and conveying means 58 disposed in the upstream conveying path 53 in the developing housing 10 from the outlet 62a.
83 is dropped on a portion opposed to, that is, on the inclined elliptical plate 586. When the toner concentration detected by the detector 60 becomes equal to or higher than a predetermined value, the operation of the toner conveying means in the supply pipe 62 is stopped, and the supply of the toner into the developing housing 10 is stopped.

Next, the operation and effect of the electrostatic latent image developing device 8 as described above will be summarized and described as follows. The toner dropped from the delivery port 62a formed in the delivery pipe 62 of the toner supply means is supplied to the inclined elliptical plate 586 of the upstream stirring and transporting means 58 disposed in the upstream transport path 53 as shown by the arrow in FIG. Is uniformly distributed on both sides from the central portion in the axial direction, and is mixed with the developer 100 in the developing housing 10. The developer 100 present in the upstream conveyance path 53 is conveyed from the central portion in the axial direction to both side portions in the axial direction while being stirred by the action of the pair of spiral blades 582 and 583 of the upstream stirring and conveying means 58.
Since the conveying capacity of the upstream stirring and conveying means 58 is set to be relatively small, the developer 100 is conveyed by the upstream stirring and conveying means 58 from the center in the axial direction to both sides in the axial direction at a relatively low speed. Let me stir. Developer 1 conveyed to both axial sides by upstream stirring / conveying means 58
00 is transferred forward through developer transfer ports 554 and 555 provided at both ends in the width direction of the upstream partition means 55, and is introduced into the middle flow path 52.

The developer 100 introduced into the middle conveying path 52 by the upstream stirring and conveying means 58 is supplied to the middle stirring and conveying means 5.
While being stirred by the action of the spiral blades 572 and 573 of No. 7, it is conveyed from both sides in the axial direction toward the center in the axial direction. The developer conveyed from both axial sides to the central portion in the axial direction by the middle stream stirring and transporting means 57 is transported to the downstream transport path 51 through a developer transport port 543 provided in the central portion of the downstream partitioning means 54, A part of the developer 100 is transported to the rear, that is, to the upstream transport path 53 through a developer transport port 553 provided at the center of the upstream partition means 55 in the width direction. At this time, the developer 100 conveyed from one side in the axial direction is appropriately distributed to both sides in the axial direction, and the developer conveyed from the other side in the axial direction, by the action of the inclined elliptical plate 574 in the middle flow stirring and conveying means 57 100 are appropriately distributed on both axial sides.

The developer transported to the downstream transport path 51 by the middle-flow agitating / conveying means 57 is moved from the central portion in the axial direction to both sides in the axial direction while being stirred by the action of the spiral blades 562 and 563 of the downstream agitating / conveying means 56. Conveyed. Then, the developer 100 conveyed to both sides in the axial direction is transferred backward through the developer transfer ports 544 and 545 provided on both sides in the width direction of the downstream partitioning means 54, and is returned to the middle flow path 52. Thereafter, the mixture is conveyed from both sides in the axial direction toward the center in the axial direction while being stirred by the action of the medium-flow stirring and conveying means 57.

Continuing the description with reference to FIG. 1, on the downstream side (left side in FIG. 1) of the downstream transport path 51, the second
The second sleeve member 31 of the developer applying means 30 is rotated in the direction indicated by the arrow 37. In the developer pumping area indicated by reference numeral 38 in FIG.
A part of the developer 100 being conveyed toward both sides in the width direction while being agitated by the operation of the second sleeve 6 is changed to the second sleeve member 31 by the magnetic field formed by the second magnet means 32.
Pumped to the surrounding surface. The developer 100 pumped to the peripheral surface of the second sleeve member 31
It is moved in the direction shown by the arrow 37 in conjunction with the rotation of 1. An ear-cutting plate 41 constituting the ear-cutting means 40 acts on the developer 100 which is magnetically held on the peripheral surface of the second sleeve member 31 and is moved, so that excess developer 100
Is removed from the second sleeve member 31, and the layer thickness of the developer 100 held on the peripheral surface of the second sleeve member 31 is appropriately regulated. The second sleeve member 31 constituting the second developer applying unit 30 and the first sleeve member 21 constituting the first developer applying unit 20 are opposed to each other on the upstream side of the repulsive magnetic field area 34 where the second sleeve member 31 is opposed to the first sleeve member 21. The developer 100 held on the peripheral surface of the first sleeve member 31 is rotated by the magnetic field formed by the rotating first magnet unit 22 of the first developer application unit 20. Transferred to the surface. The developer that is magnetically attracted to the peripheral surface of the second sleeve member 31 and moves in the direction indicated by the arrow 37 is in contact with the first sleeve member 21 of the first developer applying unit 20. The repulsive magnetic field region 3 is located at a position facing the second sleeve member 31 constituting the second developer applying unit 30.
4 cannot be passed here. The developer 100 transferred to the peripheral surface of the first sleeve member 21 and magnetically held therein moves along with the rotation of the first sleeve member 21 in the direction indicated by the arrow 25,
It is moved through the upstream half (upper half in FIG. 1) of the development zone 6. For this reason, in the upstream half of the developing zone 6, a so-called oscillating magnetic field is generated due to the rotation of the first magnet means 22 in the opposite direction to the first sleeve member 21. The toner magnetically attracted to the peripheral surface of the member 21 flies in a manner of bouncing and flies, effectively moving to the electrostatic latent image formed on the peripheral surface of the rotating drum 2, and Is developed.

The developer 100 held on the peripheral surface of the first sleeve member 21 and passed through the developing area 6 is
When viewed in the rotational direction of the rotary sleeve member 21, the upstream side of the repulsive magnetic field area 34, that is, the first developer applying unit 20 and the second
The second side of the developing zone 6 where the developer applying unit 30
The developer is transferred to the peripheral surface of the second sleeve member 31 due to the magnetic field formed by the second magnet means 32 of the developer applying means 30. Then, the developer transferred to the second sleeve member 31 and magnetically attracted and held therein is transferred to the second sleeve member 3.
It moves with rotation in the direction indicated by the arrow 37 of FIG. 1 and is moved through the downstream half (lower half in FIG. 1) of the developing zone 6. For this reason, in the downstream half of the developing zone 6,
Developer 1 held on the peripheral surface of second sleeve member 31
00 rubs the peripheral surface of the rotating drum 2 to apply a developing action to the electrostatic latent image formed on the peripheral surface of the rotating drum 2. In this way, the electrostatic latent image formed on the peripheral surface of the rotary drum 2 is subjected to the developing action of the first developer applying means 20 in the upstream half of the developing zone 6 and then the downstream half of the developing zone 6 The developing unit receives the developing action of the second developer applying unit 30 and is developed into a toner image.

The developer 100 held on the peripheral surface of the second sleeve member 31 of the second developer applying means 31 and passed through the developing area 6 has substantially a magnetic attraction force in the developer peeling area 35. The developer 100 which is being stirred and conveyed by the downstream stirring and conveying means 56 in the developer stripping area 35 acts on the peripheral surface of the second sleeve member 31. The developer is separated from the peripheral surface of the second sleeve member 31 and is mixed with the developer 100 being stirred and conveyed by the downstream stirring and conveying means 56. Then, in the developer pumping area 38, the second sleeve member 31 of the second developer applying unit 30 is again used.
It is effectively stirred before being pumped to the surrounding surface.

As described above, in the illustrated embodiment,
The developer held on the peripheral surface of the first sleeve member 21 of the first developer applying unit 20 and passing through the developing area 6 is formed by the second magnet unit 32 constituting the second developer applying unit 31. Is transferred to the peripheral surface of the second sleeve member 31 due to the generated magnetic field, so that the first magnet means 22 is configured to rotate so that the developer separation area cannot be provided. Delivery of the developer from the means 20 to the second developer applying means 31 is facilitated. In addition, since a cleaning blade or the like is not used for detaching the developer held on the peripheral surface of the first sleeve member 21 of the first developer applying means 20, toner fusion and damage to the sleeve member are prevented beforehand. be able to. Then, the developing area 6 is held on the peripheral surface of the second sleeve member 31 of the second developer applying unit 31.
The developer 100 that has been passed through is separated due to substantially no magnetic attraction force in the developer peeling area 35 formed in the second developer applying unit 31.
No separating means such as a cleaning blade is required for removing the developer.

Next, another embodiment constituted according to the present invention will be described with reference to FIG. Note that the first developer applying means 20 and the second developer applying means 30 in the embodiment shown in FIG. 3 are substantially the same as those in the embodiment shown in FIGS. The same reference numerals are given and the description is omitted. In the present embodiment, the ear cutting means 40 is disposed in the width direction (the direction perpendicular to the paper surface in FIG. 1) along the first developer applying means 20. Further, a developer stirring / conveying mechanism 70 is provided behind the first developer applying unit 20 and the second developer applying unit 30. The developer stirring and conveying mechanism 70 includes a rotating shaft 71 rotatably mounted on the developing housing 10,
And a plurality of paddles 72 provided on the rotating shaft 71.
3 is driven to rotate. A toner hopper 80 is provided at an upper portion of the developing housing 10.
A toner replenishing roller 81 having a plurality of concave portions on its surface is provided below the toner hopper 80. The toner replenishing roller 81 is driven to rotate by driving means (not shown) when the toner concentration of the developer in the developing housing 10 detected by a toner concentration detector (not shown) provided in the developing housing 10 becomes lower than a predetermined value. It is configured to be. When the toner supply roller 81 is rotated, the toner in the toner hopper 80 falls into the developing housing 10.

The embodiment shown in FIG. 3 is configured as described above, and its operation will be described below. When the developer stirring and conveying mechanism 70 is rotated in the direction shown by the arrow 73, the developer in the developing housing 10 is stirred while the first
The developer is conveyed toward the developer applying means 20. The first developer applying unit 20 magnetically pumps the developer to the peripheral surface of the first sleeve member 21 on the upstream side of the ear cutting unit 40. The developer that is magnetically attracted to the peripheral surface of the second sleeve member 31 and moves in the direction indicated by the arrow 37 is in contact with the first sleeve member 21 of the first developer applying unit 20. Since the repulsive magnetic field area 34 is formed at a position facing the second sleeve member 31 constituting the second developer applying unit 30, the repulsive magnetic field area cannot pass therethrough. The developer 100 magnetically attracted to the peripheral surface of the first sleeve member 21 is moved in a direction indicated by an arrow 25 in association with the rotation of the sleeve member 21, and is moved to a predetermined layer thickness by the ear cutting means 40. Be regulated. And the first
The developer 100 retained on the peripheral surface of the sleeve member 21 and passed through the development area 6 is located on the upstream side of the repulsive magnetic field area 34 when viewed in the rotation direction of the first rotating sleeve member 21.
That is, the first developer application unit 20 and the second developer application unit 30 are transferred to the peripheral surface of the second sleeve member 31 of the second developer application unit 30 on the side of the development area 6 where the second developer application unit 30 faces. .
The developer phase-adjusted and magnetically attracted and held by the second sleeve member 31 moves accompanying rotation of the second sleeve member 31 in the direction indicated by the arrow 37, and moves in the downstream half of the development area 6. (Lower half in FIG. 1). Therefore, in the downstream half of the developing zone 6, the developer 100 held on the peripheral surface of the second sleeve member 31 rubs the peripheral surface of the rotary drum 2 and is formed on the peripheral surface of the rotary drum 2. The developing action is applied to the electrostatic latent image. In this way, the electrostatic latent image formed on the peripheral surface of the rotary drum 2 is subjected to the developing action of the first developer applying means 20 in the upstream half of the developing zone 6 and then the downstream half of the developing zone 6 The portion receives the developing action of the second developer applying unit 30 and is developed into a toner image.

The developer 100 held on the peripheral surface of the second sleeve member 31 of the second developer applying means 31 and passed through the developing area 6 has substantially a magnetic attraction force in the developer peeling area 35. The developer 100 is stirred by the developer agitating and conveying mechanism 70 in the developer peeling area 35 and acts on the peripheral surface of the second sleeve member 31. The developer is separated from the peripheral surface of the second sleeve member 31 and is mixed with the developer 100 being stirred and conveyed by the developer stirring and conveying mechanism 70. Then, the water is effectively stirred before being pumped again to the peripheral surface of the first sleeve member 21 of the first developer applying unit 20.

[0034]

The electrostatic latent image developing device according to the present invention is constructed as described above, and has the following effects.

That is, in the electrostatic latent image developing device constructed according to the present invention, the developer held on the peripheral surface of the first sleeve member of the first developer applying means and passing through the developing area is charged by the second developer applying means.
Is transferred to the peripheral surface of the second sleeve member due to the magnetic field formed by the second magnet means constituting the developer application means, and the first magnet means is configured to rotate so as to rotate the developer. The transfer of the developer from the first developer application unit, in which the separation area cannot be provided, to the second developer application unit is facilitated. Further, since the cleaning blade or the like is not used for detaching the developer held on the peripheral surface of the first sleeve member of the first developer applying means, it is possible to prevent the toner fusion and the damage of the sleeve member beforehand. it can. Then, the developer held on the peripheral surface of the second sleeve member of the second developer applying unit and passed through the developing region is magnetically separated in the developer peeling region formed in the second developer applying unit. Since the developer is separated due to substantially no suction force, a separating means such as a cleaning blade is not required for separating the developer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of an electrostatic latent image developing device configured according to the present invention.

FIG. 2 is a plan view of the electrostatic latent image developing device shown in FIG. 1 with a cover member that covers an upper surface of a developing housing omitted.

FIG. 3 is a sectional view showing another embodiment of the electrostatic latent image developing device constituted according to the present invention.

[Explanation of symbols]

 2: rotating drum 6: developing area 8: electrostatic latent image developing device 10: developing housing 19: cover member 20: first developer applying means 21: first sleeve member 22: first magnet means 30: first No. 2 developer application means 31: second sleeve member 32: second magnet means 34: repulsive magnetic field area 35: developer peeling area 40: ear cutting means 50: developer stirring and transport mechanism 51: downstream transport path 52: Midstream conveying path 53: Upstream conveying path 54: Downstream partitioning means 55: Upstream partitioning means 56: Downstream stirring and conveying means 57: Midstream stirring and conveying means 58: Upstream stirring and conveying means 60: Toner concentration detector 62: Feeding pipe 70: Development Agent stirring / conveying mechanism 80: Toner hopper 81: Toner supply roller 100: Developer

Claims (1)

[Claims] An electrostatic latent image formed on an image carrier that is moved through a developing area is formed by applying a developer comprising carrier particles and toner on the image carrier in the developing area. An electrostatic latent image developing device for developing an image, comprising: a developing housing for accommodating a developer; a first housing disposed in the developing housing, for adsorbing and holding the developer on a peripheral surface and transporting the developer to the developing area. And a developer application unit disposed downstream of the image carrier with respect to the first developer application unit in the moving direction of the image carrier, and the developer application unit on the development area side facing the first developer application unit. A second developer application unit that adsorbs and holds the developer held on the peripheral surface of the first developer application unit on the peripheral surface and transports the developer to the development area; Moves in the developing region in the forward direction with respect to the moving direction of the image carrier. A first sleeve member rotatably driven as described above, and first magnet means disposed in the first sleeve member and rotatably driven in a direction opposite to the first sleeve member. The second developer applying means includes a second sleeve member that is rotationally driven to move in a forward direction with respect to a moving direction of the image carrier in the developing area, and is disposed in the second sleeve member. And a second magnet means that is stationary and fixed at a predetermined position, the second magnet means forming a repulsive magnetic field area at a position facing the first developer applying means, and An electrostatic latent image developing device, wherein a developer peeling area substantially free of a magnetic attraction force is provided.