JPH1090986A - Electrostatic latent image developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device in which toner can be sufficiently mixed with a carrier particle, and the density difference between the center part and both end parts of a transfer image can be minimized by providing such a structure as to supply the toner to the part of a third stirring carrying member where a first spiral blade and a second spiral blade are mutually opposed. SOLUTION: A first stirring carrying member 62 carries a developer from both end parts to the center part. A second stirring carrying member 64 is arranged on the downstream side of the first stirring carrying member 62 in opposition to a developer applying means 26 to carry the developer from the center part to both the end parts. A third stirring carrying member 66 is arranged on the upstream side of the first stirring carrying member 62 to carry the developer from the center part to both the end parts. A bulkhead 38 is arranged between the first stirring carrying member 62 and the third stirring carrying member 66, and has a developer transfer port in the center part. Therefore, the toner can be supplied to the part of the third stirring carrying member 66 where first spiral blade and second spiral blade formed so that the spiral direction are mutually reversed are mutually opposed.

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 device for developing an electrostatic latent image into a toner image in an image forming machine such as an electrostatic copying machine and an electrostatic printing machine.

[0002]

2. Description of the Related Art As is well known, an electrostatic latent image developing apparatus in which a developer comprising toner and carrier particles is used for developing an electrostatic latent image in an image generator is widely used. . The electrostatic latent image developing device includes a developing housing for containing a developer, a developer applying unit for applying the developer in the developing housing to the electrostatic latent image, and agitating the developer in the developing housing. And a developer stirring / conveying means for conveying the toner in a required direction, and a toner supplying means for supplying toner into the developing housing. The developer applying means usually includes a rotating sleeve member, holds the developer on the peripheral surface of the sleeve member, conveys the developer to a developing area, and selects a toner in the developer into an electrostatic latent image in the developing area. The electrostatic latent image is developed into a toner image. When the toner in the developer is consumed according to the development of the electrostatic latent image, the toner is supplied from the toner supply unit into the development housing. The developer stirring and conveying means stirs the developer in the developing housing to mix and frictionally charge the toner and the carrier particles, and convey the toner and the carrier particles in a required direction.

In the above-described electrostatic latent image developing apparatus, the developer is sufficiently stirred before being transported to the developing area while being held by the developer applying means, and the ratio between toner and carrier particles is required. It is important that the developer which is within the range and is uniformly mixed is applied to the electrostatic latent image. Further, on the downstream side of the developing area, the toner adheres to the electrostatic latent image, and therefore, the developer having a reduced toner ratio is effectively separated from the developer applying means, and the developer is removed from the developing housing. It is important that the powder be stirred and transported again. In order to satisfy such requirements for stirring and transporting of the developer, Japanese Utility Model Publication No. 50-33333 has been proposed.
Japanese Patent Application Laid-Open Publication No. H10-157, discloses a developer stirring / conveying device including a first stirring / conveying member extending adjacent to a developer applying unit and a second stirring / conveying member disposed upstream of the first stirring / conveying member. ing. The first stirring / conveying member is formed with a rotating shaft extending in the width direction (that is, the axial direction of the rotating sleeve member in the developer applying unit) and spaced apart from the rotating shaft in the axial direction, and the winding directions are opposite to each other. Consisting of a pair of spiral blades,
The second stirring / conveying member also includes a rotating shaft extending in the width direction and a pair of spiral blades formed at an axial distance from the rotating shaft and having winding directions opposite to each other. The first stirring and conveying member is rotated in a predetermined direction, and conveys the developer from both axial end portions toward the central portion in the axial direction while stirring the developer. The developer is transferred to the central portion in the axial direction of the first stirring and conveying member. Let me transport you. Similarly, the second stirring and conveying member rotated in a predetermined direction conveys the developer from the axial center to both ends in the axial direction while stirring the developer, and performs the first stirring and conveying at both ends in the axial direction. The developer is transferred to the member. However, the developer stirring and conveying device disclosed in the above publication has only the first stirring and conveying member that stirs and transfers the developer to the second stirring and conveying member that supplies the developer to the developer applying unit. Therefore, there is a problem that the toner and the carrier particles cannot be sufficiently mixed.

A technique for solving the above-mentioned problem of the developer stirring and conveying device disclosed in Japanese Utility Model Publication No. 50-27333 is proposed in Japanese Patent Application Laid-Open No. Hei 7-175306.
Japanese Patent Application Laid-Open No. 7-175306 discloses an upstream partition and a downstream partition which are arranged in parallel in a housing at an interval and each have a developer transfer port in the center, and an upstream partition and a downstream partition. A first agitating and conveying member having a first spiral blade and a second spiral blade, which are disposed between the first spiral blade and the second spiral blade, in which the winding directions of the spirals for transporting the developer from both end portions toward the central portion are formed opposite to each other; A first spiral blade and a second spiral disposed on the downstream side of the downstream partition wall along the downstream partition wall and configured to reverse the spiral directions of spirals for transporting the developer from the central portion to both ends. The second stirring / conveying member provided with the blades and a spiral arranged at the upstream side of the upstream partition along the upstream partition and conveying the developer from the central portion toward both ends are opposite in winding direction. Third stirring provided with a first spiral blade and a second spiral blade formed in Feeding; and a member, the construction and developer stirring and conveying device so as to supply the developing agent application means the developer conveyed by the second agitating and conveying member is disclosed.

[0005]

Problems to be solved by the invention
No. 75306 discloses a developer stirring and conveying device.
Although the toner and the carrier particles can be sufficiently mixed by the third stirring and conveying member and the first stirring and conveying member, the developer conveyed by the first stirring and conveying member is in the central portion of the downstream partition. Is supplied to the second stirring and conveying member side only from the developer transfer port provided in the developer transfer means, the pressure of the developer acting on the developer application means is high at the central portion facing the developer transfer port, It goes lower as you go. As a result, the density of the transferred image becomes darker at the center and lighter at both ends,
In particular, there is a problem that so-called gray unevenness appears remarkably in a gray image.

The present invention has been made in view of the above-mentioned facts, and its main technical problem is that the toner and the carrier particles can be sufficiently mixed, and the density at the center and both ends of the transferred image is high. An object of the present invention is to provide an electrostatic latent image developing device capable of reducing the difference.

[0007]

According to the present invention, in order to solve the above-mentioned technical problems, a developing housing and a developer provided in the developing housing and formed in the developing housing are formed on an image carrier. And a developer agitating / conveying means disposed in the developing housing for agitating and transporting the developer to the developer applying means. In the electro-latent image developing apparatus, the developer stirring / conveying means includes a first helical blade and a second helical blade in which spiral directions for conveying the developer from both end portions toward the center are formed in opposite directions. A first stirring / conveying member provided, and a developer disposed downstream of the first stirring / conveying member and parallel to the first stirring / conveying member and opposed to the developer applying means, and moving the developer from a central portion. The winding directions of the spirals conveyed toward both ends are A second stirring / transporting member having a first spiral blade and a second spiral blade formed oppositely; and a developing device disposed upstream of the first stirring / transporting member in parallel with the first stirring / transporting member. A third stirring / transporting member including a first spiral blade and a second spiral blade in which a spiral for transporting the agent from the central portion toward both ends is formed in opposite directions to each other;
And a partition wall provided with a developer transfer port at the center thereof, disposed between the third stirring and conveying member and the third stirring and conveying member, wherein the first spiral blade of the third stirring and conveying member and the first spiral blade are provided. An electrostatic latent image developing device is provided, wherein toner is supplied to a portion facing the second spiral blade.

[0008]

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

FIG. 1 shows an electrostatic latent image developing apparatus constructed according to the present invention, together with a part of a rotating drum constituting an electrostatic copying machine. The rotating drum 2 as an image carrier having an appropriate electrostatic photoreceptor disposed on the peripheral surface is rotated in a direction indicated by an arrow 4 so as to pass through a developing area 6. 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 an appropriate method known per se. In the developing area 6, the electrostatic latent image on the peripheral surface of the rotating drum 2 is developed into a toner image by an electrostatic latent image developing device generally denoted by reference numeral 8 provided with a developer stirring and conveying means 7. The toner image developed in this manner is transferred to a transfer member such as plain paper on the downstream side of the development area 6 and fixed there.

Referring to FIGS. 1 and 2, the electrostatic latent image developing device 8 includes a developing housing 10. A developing housing 10 that can be molded from any suitable synthetic resin includes a front end wall 18 and a rear end wall 20 along with a bottom wall 12 and a rear wall 16 that extends substantially vertically upward from the rear edge of the bottom wall 12. I have. The rear wall 16 is connected to an upper wall 22 that projects substantially horizontally forward from the upper end thereof, and a cover wall 24 is further connected to the upper wall 22.

A developer applying means 26 is provided at the forefront of the developing housing 10 (the leftmost part in FIG. 1, and the uppermost part in FIG. 2). The developer applying means 26 includes a sleeve member 28 extending substantially horizontally in the width direction, and a permanent magnet member 30 disposed in the sleeve member 28. The sleeve member 28 is made of a non-magnetic material such as aluminum and is rotatably mounted.
The permanent magnet member 30 is fixed at a predetermined position. As shown in FIG. 2, the rotating shaft 31 to which the sleeve member 28 is fixed projects through the rear end wall 20 of the developing housing 10 and projects rearward. An input gear 32 is provided at the projecting end. Fixed. The input gear 32 is operatively connected to a rotary drive source (not shown), which may be an electric motor, via an input gear (not shown) of the rotary drum 2, and is driven to rotate in a direction indicated by an arrow 34. Can be
Free edge 35 of the cover wall 24 of the developing housing 10
Is located close to the peripheral surface of the sleeve member 28 of the developer applying means 26, and is held on the peripheral surface of the sleeve member 28 and conveyed to the developing area 6 as described in further detail later. It functions as a so-called ear cutting means for regulating the amount of the developer.

A developer agitating / conveying means 7 is provided behind the developer applying means 26. The developer stirring / conveying means 7 is a partition wall disposed at a predetermined distance from the rear wall 16 of the developing housing 10 and parallel to the rear wall 16 in the front-rear direction (the left-right direction in FIG. 1 and the up-down direction in FIG. 2). 38. The partition wall 38 is provided on the bottom wall 1 of the developing housing 8.
2 are defined by upstanding walls 42 and 44 projecting substantially vertically upward. The lower end side surfaces of each of the upright walls 42 and 44 constituting the partition wall 38,
As shown in FIG. 1, it is formed in a concave arc shape. The upright walls 42 and 44 have opposing inner ends spaced apart from each other as shown in FIG.
A developer transfer port 50 is formed at a central portion of the developer transfer port. 2, a predetermined distance is provided between the outer end of each of the upright walls 42 and 44 and the front end wall 18 and the rear end wall 20 of the developing housing 8 as shown in FIG. At both ends in the width direction, developer transfer ports 52 and 5 are provided, respectively.
4 are formed.

The illustrated developer stirring and conveying means 7 is located downstream of the partition 38 (left side in FIG. 1, upper side in FIG. 2).
Agitating / conveying member 62 disposed in parallel with partition 38
A second stirring / conveying member 64 disposed downstream of the first stirring / conveying member 62 in parallel with the first stirring / conveying member 62 and opposed to the developer applying unit 26; On the upstream side (the right side in FIG. 1, the lower side in FIG. 2) of the third member 38, a third stirring / conveying member 66 is provided in parallel along the partition wall 38. The first stirring and conveying member 62, the second stirring and conveying member 64, and the third stirring and conveying member 66 are arranged on the same plane in the illustrated embodiment.

The first stirring and conveying member 62 has a rotating shaft 68 rotatably mounted between both end walls 18 and 20 of the developing housing 10. A pair of first spiral blades 7 are provided on the rotating shaft 68 at intervals in the width direction (ie, axial direction).
Zero and second spiral blades 72 are formed. The inner ends of the first spiral blade 70 and the second spiral blade 72
In any case, the first stirring and conveying member 62 does not reach the center in the axial direction, and the first stirring and conveying member 62 is provided with a first spiral blade 70 and a second spiral blade 72 at the central portion in the axial direction. Absent. First spiral blade 70 and second spiral blade 72
Means that the spiral directions are opposite to each other. The outer diameter of the first spiral blade 70 and the outer diameter of the second spiral blade 72 are the same. The first developer stirring and conveying member 62 thus configured is rotated in a direction indicated by an arrow 108 in FIG. 1, and conveys the developer from both ends toward the center while stirring. An inclined elliptical plate 73 is provided at the axial center of the rotating shaft 68. This inclined elliptical plate 73
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 first spiral blade 70 and the second spiral blade 72.

The second stirring and conveying member 64 also has a rotating shaft 74 rotatably mounted between both end walls 18 and 20 of the developing housing 10. A pair of first spiral blades 76 and second spiral blades 78 are formed on the rotating shaft 74 at intervals in the width direction (that is, the axial direction). The inner ends of the first spiral blade 76 and the second spiral blade 78 reach each other in the illustrated embodiment to the axial center. The first spiral blade 76 and the second spiral blade 78 are formed such that the spiral winding directions are opposite to each other. First
The outer diameter of the spiral blade 76 and the outer diameter of the second spiral blade 78 are the same. The first spiral blade 7 is provided at both ends of the rotating shaft 74.
A first auxiliary spiral blade 80 and a second auxiliary spiral blade 82 are formed opposite to the sixth and second spiral blades 78, respectively. The outer diameters of the first auxiliary spiral blade 80 and the second auxiliary spiral blade 82 may be the same as the outer diameters of the first spiral blade 76 and the second spiral blade 78. The winding direction of the first auxiliary spiral blade 80 and the second auxiliary spiral blade 82 extending over an angle range of approximately 360 degrees is relative to the winding direction of the opposing first spiral blade 76 and second spiral blade 78. In the opposite direction. The second developer stirring and conveying member 64 configured as described above is rotated in a direction indicated by an arrow 110 in FIG. 1, and conveys the developer from the center to both ends while stirring.

Continuing the description with reference to FIG.
The agitating and conveying member 66 also has a rotating shaft 84 rotatably mounted between both end walls 18 and 20 of the developing housing 10. A pair of first spiral blades 86 and second spiral blades 88 are formed on the rotating shaft 84 at intervals in the width direction (that is, the axial direction). The inner ends of the first spiral blade 86 and the second spiral blade 88 do not reach the axial center of the third stirring / conveying member 66 in any case.
The first spiral blade 86 and the second spiral blade 88 are not provided at the axial center portion of the stirring and conveying member 66. The first spiral blade 86 and the second spiral blade 88 are formed such that the spiral winding directions are opposite to each other. First spiral blade 8
6 and the outer diameter of the second spiral blade 88 are the same.
The outer ends in the width direction of the first spiral blade 86 and the second spiral blade 88 correspond to substantially the widthwise intermediate positions of the developer transfer ports 52 and 54 provided at both ends in the width direction of the partition wall 38. It is desirable to be located. The first ends of the rotating shaft 84
A first auxiliary spiral blade 90 and a second auxiliary spiral blade 92 are formed to face the spiral blade 86 and the second spiral blade 88, respectively. First auxiliary spiral blade 90
The outer diameter of the second auxiliary spiral blade 92 may be the same as the outer diameter of the first spiral blade 86 and the second spiral blade 88. The winding direction of the first auxiliary spiral blade 90 and the second auxiliary spiral blade 92 extending over an angle range of about 360 degrees is the same as the winding direction of the opposing first spiral blade 86 and second spiral blade 88. In the opposite direction. The third developer stirring / conveying member 66 configured as described above is indicated by an arrow 10 in FIG.
6, the developer is conveyed from the center toward both ends while stirring. An inclined elliptical plate 93 is provided at the axial center of the rotating shaft 84. The axial dimension of the inclined elliptical plate 93 is substantially the same as the width dimension of the developer transfer port 50 provided at the center of the side partition wall 38 in the width direction. The inclined elliptical plate 93 has a circular shape in a side view similarly to the inclined elliptical plate 73, and the diameter of the circular shape is equal to the first spiral blade 86 and the second spiral blade 8.
8 is formed substantially the same as the outside diameter.

Referring to FIGS. 2 and 3, the rotating shaft 68 of the first stirring and conveying member 62, the rotating shaft 74 of the second stirring and conveying member 64, and the rotating shaft 84 of the third stirring and conveying member 66 Are projected rearward through the rear end wall 20 of the developing housing 10, and these rotating shafts 6
8, 74 and 84 have input gears 98, 1
00 and 102 are fixed. The input gear 102 meshes with the input gear 98, and the input gear 98
And the input gear 100 is engaged with the rear end wall 2.
The transmission gear 104 is engaged with the input gear 32 of the developer applying unit 26 via a transmission gear 104 rotatably mounted at zero. Accordingly, when the sleeve member 28 of the developer applying unit 26 is rotated in the direction indicated by the arrow 34 by a rotation drive source (not shown), the first stirring / conveying member 62 is moved by the arrow 108 as shown in FIG. In the direction shown, the second stirring and conveying member 64 is rotated in the direction shown by the arrow 110, and the third stirring and conveying member 66 is turned in the direction shown by the arrow 106.

As shown in FIG. 1, the developing housing 10
A developer 112 composed of toner and carrier particles is accommodated therein. The developer 112 flows upstream of the partition 38 (right side in FIG. 1, lower side in FIG. 2) and downstream of the partition 38 (left side in FIG. 1, upper side in FIG. 2).
Are appropriately dispersed and accommodated. The third stirring and conveying member 66 rotated in the direction indicated by the arrow 106 conveys the developer from the central portion in the axial direction to both ends in the axial direction while stirring the developer on the upstream side of the partition wall 38. That is, the third stirring and conveying member 6
6, the first spiral blade 86 transports the developer from the central portion in the axial direction toward one end in the axial direction (the left end portion in FIG. 2) while stirring the developer, and the second spiral blade of the third stirring and transporting member 66. 88
Transports the developer from the center in the axial direction to the other end in the width direction (the right end in FIG. 2) while stirring the developer. The first auxiliary spiral blade 90 of the third stirring / conveying member 66 forces the developer axially inward at one end in the width direction, and the first auxiliary spiral blade 92 rotates the developer at the other axial end. Force inward direction. The first stirring and conveying member 62 rotated in the direction indicated by the arrow 108 conveys the developer from both ends in the axial direction toward the center in the axial direction while stirring the developer downstream of the partition wall 38. That is, the first spiral blade 70 of the first stirring and conveying member 62 conveys the developer from one end in the axial direction (left end in FIG. 2) toward the center in the axial direction while stirring the developer. The second spiral blade 72 of the member 62 conveys the developer with stirring. The second stirring and conveying member 64 rotated in the direction indicated by the arrow 110 conveys the developer from the central portion in the axial direction to both ends in the axial direction while stirring the developer downstream of the first stirring and conveying member 62. That is, the second stirring and conveying member 64
The first spiral blade 76 transports the developer from the central portion in the axial direction toward one end in the axial direction (the left end portion in FIG. 2) while stirring the developer, and the second spiral blade 78 of the second stirring and transporting member 64. Transports the developer from the center in the axial direction to the other end in the axial direction (the right end in FIG. 2) while stirring the developer. The first auxiliary spiral blade 80 of the second stirring and conveying member 64 forces the developer axially inward at one end in the axial direction, and the second auxiliary spiral blade 82 axially drives the developer at the other end in the axial direction. Force inward direction.

The conveying capacity of the first stirring and conveying member 62 for conveying the developer from both ends in the axial direction toward the center in the axial direction is as follows.
A second stirring and conveying member 64 and a third stirring and conveying member 6 for conveying the developer from the axial center toward both ends in the axial direction;
6 is set to be larger than each transfer capacity. The transport of the developer from the axial ends to the axial center and the transport of the developer from the axial center to the axial ends are substantially balanced, and the developer is sufficiently uniform over the entire axial direction. In order to make it exist, the conveying capacity of the first stirring and conveying member 62 is configured to substantially match the sum of the conveying ability of the second stirring and conveying member 64 and the conveying ability of the third stirring and conveying member 66. It is desirable to do. Further, it is desirable that the transfer capacity of the second stirring and conveying member 64 is set to be larger than that of the third stirring and conveying member 66, and the conveying capacity of the second stirring and conveying member 64 is set to be the third stirring and conveying member. 1.2 of the transfer capacity of the member 66
It is preferably about 2.5 times. The conveying capacity of the first stirring and conveying member 62, the second stirring and conveying member 64 and the third stirring and conveying member 66 is determined by the first and second spiral blades 70 and 72, 76 and 78 and 86 and 88. The rotation speed, the pitch and the outer diameter can be set as required by appropriately setting. In the illustrated embodiment, the number of rotations per unit time of the second stirring and conveying member 64 and the number of rotations per unit time of the third stirring and conveying member 66 are the same. The rotation speed of the stirring and conveying member 62 per unit time is set to be large. The pitch of the first and second spiral blades 76 and 78 of the second stirring and conveying member 64 is the same as the pitch of the first and second spiral blades 86 and 88 of the third stirring and conveying member 66.
And the pitch of the first and second spiral blades 70 and 72 of the first stirring and conveying member 62 is even greater than the pitch of the first and second spiral blades 76 and 78 of the second stirring and conveying member 64. . The first of the third stirring and conveying members 66
And the outer diameters of the second spiral blades 86 and 88 and the outer diameters of the first and second spiral blades 76 and 78 of the second stirring and conveying member 64 are the same, but the first diameter is larger than these outer diameters. The outer diameters of the first and second spiral blades 70 and 72 of the stirring and conveying member 62 are large.

Referring to FIGS. 1 and 2, a circular opening 114 is formed at the center of the bottom wall 12 of the developing housing 10 in the width direction facing the first stirring and conveying member 62.
Are formed. A detector 116 for detecting the toner concentration in the developer 112 is provided in the opening 114. The detector 116 detects the toner concentration in the developer 112 by detecting the magnetic permeability of the developer 112 present on the upper surface exposed in the developing housing 10 through the opening 114. It may be of the form. The electrostatic latent image developing device 8 is further provided with a toner supply unit that is activated according to the toner concentration in the developer 112 detected by the detector 116. Such a toner supply means is provided by a feed pipe 118 provided on the upper wall 22 of the developing housing 10.
Is provided. One end of the feed pipe 118 is located above the axial center of the third stirring / conveying member 66, and a feed port 120 communicating with the inside of the developing housing 10 is formed on the lower surface thereof. The other end of the feeding pipe 118 extending from the one end to the front end in the width direction is communicated with a toner container (not shown), and the toner conveying means which can be constituted by a spiral blade in the feeding pipe 118. (Not shown) are provided. The above detector 11
When the toner concentration in the developer 112 detected by the printer 6 becomes equal to or lower than a predetermined value, the toner conveying means in the feed pipe 118 is operated, and the toner is conveyed from the toner container through the feed pipe 118, and is sent from the outlet 120. The first spiral blade 86 of the third stirring and conveying member 66 in the developing housing 10 and the second spiral blade 86
The spiral blade 88 is dropped on a portion facing the spiral blade 88, that is, on the inclined elliptical plate 93. When the toner concentration detected by the detector 116 becomes equal to or higher than a predetermined value, the operation of the toner conveying means in the feed pipe 118 is stopped, and the developing housing 10
The supply of the toner to the inside is stopped.

Next, the operation and effect of the electrostatic latent image developing device 8 provided with the developer stirring / conveying means 7 as described above will be summarized as follows. As shown by the arrows in FIG. 2, the toner dropped from the delivery port 120 formed in the delivery pipe 118 of the toner supply means is moved from the central portion in the axial direction by the action of the inclined elliptical plate 93 of the third stirring / conveying member 66. The toner is evenly distributed on both sides and mixed with the developer 112 in the developing housing 10. The developer 112 existing on the upstream side (the right side in FIG. 1) of the partition 38 is the third developer.
While being stirred by the action of the first and second helical blades 86 and 88 of the stirring and conveying member 66, the sheet is conveyed from the axial center to both sides in the axial direction. Since the carrying capacity of the third stirring and carrying member 66 is set relatively small, the developer 1
12 is conveyed at a relatively low speed from the center in the axial direction to both sides in the axial direction by the third stirring / conveying member 66, and is sufficiently stirred at this time. The developer 112 conveyed to both sides in the axial direction by the third stirring / conveying member 66 is transferred forward through the developer transfer ports 52 and 54 provided on both sides in the width direction of the partition 38, and is moved forward. Introduced downstream.

Next, the developer 112 introduced on the downstream side of the partition 38 is stirred from both sides in the axial direction while being stirred by the action of the first and second spiral blades 70 and 72 of the first stirring and conveying member 62. Transported to the center in the direction. The developer conveyed by the first stirring and conveying member 62 from both axial sides to the center in the axial direction is transferred forward, that is, to the second stirring and conveying member 64 side, and a part of the developer 112 is
Is transported rearward, that is, toward the first stirring and transporting member 62 through a developer transporting port 50 disposed at the center in the width direction of the developer.
At this time, the developer 112 conveyed from one side in the axial direction is appropriately distributed to both sides in the axial direction and is conveyed from the other side in the axial direction by the action of the inclined elliptical plate 73 in the first stirring and conveying member 62. The developer 112 is appropriately distributed on both axial sides.

The developer transferred from the axially central portion of the first stirring and conveying member 62 to the front, that is, to the second stirring and conveying member 64 is supplied to the first spiral blade 76 and the second spiral stirring member 76 of the second stirring and conveying member 64. While being stirred by the action of the second spiral blade 78, it is conveyed from the axial center to the axial both sides. Then, the developer 112 conveyed to both sides in the axial direction is transferred rearward and returned to the first stirring and conveying member 62 side, and thereafter, the first spiral blade 70 of the first stirring and conveying member 62 and While being agitated by the action of the second spiral blade 72, it is conveyed from both axial sides to the axial center.

Continuing the description with reference to FIGS. 1 and 2, on the downstream side (left side in FIG. 1, upper side in FIG. 2) of the second stirring / conveying member 64, the developer applying means 2
The sixth sleeve member 28 is rotated in the direction indicated by the arrow 34. In the developer pumping area indicated by reference numeral 122 in FIG. 1, the first spiral blade 7 of the second stirring and conveying member 64
A part of the developer 112 conveyed from the axial center portion to the axial both sides while being stirred by the action of the sixth spiral blade 78 and the second spiral blade 78 causes the developer 112 to be sleeved due to the magnetic field formed by the stationary permanent magnet member 30. It is pumped to the peripheral surface of the member 28. The developer 112 pumped to the peripheral surface of the sleeve member 28 is rotated by the arrow
Are transported in the direction shown by the arrow and transported to the developing zone 6. At this time, the free edge 3 of the cover wall 24 of the developing housing 10 is
By the operation of 5, excess developer 112 is removed from the peripheral surface of the sleeve member 28. In the developing area 6, as described above, the toner in the developer 112 is selectively adhered to the electrostatic latent image formed on the peripheral surface of the rotating drum 4, and the electrostatic latent image is formed on the toner image. Developed. In the developer peeling area 124 located downstream of the developing area 6, the developer 1 is removed from the peripheral surface of the sleeve member 28 due to the magnetic field formed by the permanent magnet member 30 being reduced.
12 is removed. The toner density of the developer 112 is reduced due to consumption of the toner in the developing area 6. The developer 112 released from the peripheral surface of the sleeve member 28 is mixed into the developer 112 in the developing housing 10 and is acted on by the first spiral blade 76 and the second spiral blade 78 of the second stirring and conveying member 64. It is conveyed to both sides in the axial direction while being stirred. Since the carrying capacity of the second stirring / conveying member 64 is set to be larger than the carrying capacity of the third stirring / conveying member 66, the developer peeling area 1
At 24, the developer 112 is satisfactorily removed from the peripheral surface of the sleeve member 28, and the developer 112 is quickly mixed into the developer 112 in the developing housing 10 and stirred.

[0025]

EXPERIMENTAL EXAMPLE In the electrostatic latent image developing apparatus having the structure shown in FIGS. 1 to 3, the outer diameter of the sleeve member 28 of the developer applying means 26 is 34 mm, and the axial length of the sleeve member 28 is 321.
mm, the outer diameters of the first spiral blade 70 and the second spiral blade 72 of the first stirring and conveying member 62 are 20 mm, and the first spiral blade 76 and the second spiral blade 78 of the second stirring and conveying member 64. Has an outer diameter of 18 mm, and the outer diameter of the first spiral blade 86 and the second spiral blade 88 of the third stirring and conveying member 66 is 1 mm.
6 mm, width of the developer transfer port 50 of the partition 38 is 15 m
m, the width of the developer transfer ports 52 and 54 of the partition 38 was 30 mm, and the gray density distribution of the transferred image was measured. For comparison with the present invention, the electrostatic latent image developing apparatus according to the present invention has a configuration in which a partition is also provided between the first stirring and conveying member 62 and the second stirring and conveying member 64, and the transfer image Was measured for gray density distribution. The first stirring and conveying member 62 and the second stirring and conveying member 64
The width of the developer transfer port formed at the center of the partition wall provided between them was 30 mm, and the width of the developer transfer port provided at both ends of the partition was 30 mm. The results of the experiment are as shown in FIG. 4. In the comparative example in which a partition was also provided between the first stirring and conveying member 62 and the second stirring and conveying member 64, the concentration at the center was extremely high, It can be seen that the density decreases remarkably as the temperature increases, and the density difference between the center and both ends increases. On the other hand, in the present invention, the density difference between the center and both ends is small, so that the occurrence of so-called gray unevenness in a gray image can be prevented.

[0026]

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

That is, according to the present invention, the developer stirring / conveying means for conveying the developer to the developer applying means while stirring the first stirring means for conveying the developer from both ends toward the center thereof. A conveying member, a second stirring / conveying member disposed downstream of the first stirring / conveying member and opposed to the developer applying unit, and conveying the developer from the center toward both ends; A third stirring / conveying member disposed upstream of the stirring / conveying member and conveying the developer from the center toward both ends; and a third stirring / conveying member disposed between the first stirring / conveying member and the third stirring / conveying member. And a partition provided with a developer transfer port at the center thereof.
The toner and the carrier supplied to the portions where the first spiral blade and the second spiral blade of the stirring and conveying member oppose each other can be sufficiently stirred and mixed by the third stirring and conveying member and the first stirring and conveying member. . Further, according to the present invention, since no partition is provided between the first stirring and conveying member and the second stirring and conveying member, the first stirring and conveying member conveys from both ends toward the center. Then, the pressure of the developer sent to the second stirring and conveying member and acting on the developer applying means does not become abnormally high at the central portion. For this reason, the density difference between the center and both ends of the transferred image is small, and therefore, so-called gray unevenness in the gray image can be prevented.

[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 showing the electrostatic latent image developing device shown in FIG. 1 omitting an upper wall of a developing housing, a cover member, and the like;

FIG. 3 is a simplified diagram showing a driving connection gear in the electrostatic latent image developing device shown in FIG. 1;

FIG. 4 is a diagram showing measured values of image densities at the center and both ends of a transferred image developed using the electrostatic latent image developing device shown in FIG. 1 together with a comparative example.

[Explanation of symbols]

 2: rotating drum 6: developing area 7: developer stirring and conveying means 8: electrostatic latent image developing device 10: developing housing 26: developer applying means 28: sleeve member 30: permanent magnet member 38: partition 42: upright wall 44 : Upright wall 50: developer transfer port 52: developer transfer port 54: developer transfer port 62: first stirring and conveying member 64: second stirring and conveying means 66: third stirring and conveying means 68: rotating shaft 70 : First spiral blade 72: second spiral blade 74: rotating shaft 76: first spiral blade 78: second spiral blade 80: first auxiliary spiral blade 82: second auxiliary spiral blade 84: rotation Shaft 86: first spiral blade 88: second spiral blade 90: first auxiliary spiral blade 92: second auxiliary spiral blade 116: detector (toner concentration detector) 118: delivery pipe 120 of toner supply means : Exit

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mitsuhiro Kashiwara 1-2-2 Tamazo, Chuo-ku, Osaka Mita Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A developing housing, a developer applying means disposed in the developing housing and adapted to apply a developer in the developing housing to an electrostatic latent image formed on an image carrier, and the developing housing. And a developer stirring and conveying means for conveying the developer to the developer applying means while stirring the developer, wherein the developer stirring and conveying means is provided at both ends thereof. A first stirring / transporting member including a first spiral blade and a second spiral blade in which the spiral directions of the spirals conveyed from the first to the central portion are opposite to each other, and a downstream side of the first stirring / conveying member The spirals which are arranged in parallel with the first stirring and conveying member and opposed to the developer applying means and which convey the developer from the central portion toward both ends are formed in mutually opposite winding directions. 1 spiral blade and 2nd
A second stirring / conveying member provided with a spiral blade, and a developer disposed upstream of the first stirring / conveying member and parallel to the first stirring / conveying member to convey the developer from a central portion toward both ends. A third stirring / transporting member provided with a first spiral blade and a second spiral blade in which the spiral winding directions are formed to be opposite to each other, and between the first stirring / transporting member and the third stirring / transporting member; And a partition provided with a developer transfer port at a central portion thereof, so that toner is supplied to a portion of the third stirring / transporting member where the first spiral blade and the second spiral blade face each other. An electrostatic latent image developing device, characterized in that: