JPS6383755A - Developing device - Google Patents

Abstract

PURPOSE:To uniformly mix and agitate a developer and to contrive to stabilize mixture, agitation and supply of the developer by forming the tip part of a guide plate projecting in a 1st developer chamber in approximately a convex and setting the projecting height of the guide plate so that it becomes lower toward both end parts from the middle in the axial direction of a sleeve. CONSTITUTION:Since the magnetism of a magnetic roller 11 always attracts the developer in a 1st developer chamber 17 in the surface direction of the sleeve 12, the developer in the vicinity of the surface of the sleeve 12 is held and conveyed in the direction of an arrow (b) due to the rotation of a development roller 13. The developer, which is regulated by a layer thickness regulating member 14 to remain, flows in the direction of an arrow (e), and uniformly mixed and agitated in all. Simultaneously the flow in the axial direction of the sleeve 12 is suppressed. Since the projecting height in the vicinity of the both ends of the guide plate 18 projecting from the 1st developer chamber 17 is set low, suppression against the flow of the developer circulating in the surface direction of the sleeve 12 from an arrow (e) decreases. Consequently the fluidity of the developer in the vicinity of the both ends in the axial direction of the sleeve 12 is improved, and the developer is sufficiently mixed and agitated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dry developing device used in electrophotographic copying processes and the like.

BACKGROUND OF THE INVENTION As dry developing methods that have already been put into practical use, there are a one-component developing method using a developer made of only magnetic toner and a two-component developing method using a developer made of a mixture of a magnetic carrier and toner. -The component development method has the advantage of simplifying the developing device, making it smaller and lowering the price, but the toner requires contradictory conditions such as conductivity during development and insulation during transfer. Currently, toners with high resistance, which do not place much burden on the copying process and have good transfer characteristics, are used, and various measures are taken to improve the development characteristics. In the two-component development system, even though the developer is originally a -component developer, magnetic carrier is mixed in to ensure triboelectric charging of the toner, increase in conveyance force by improving magnetic permeability, etc., and the development and transfer characteristics of the toner itself are improved. Although this method is good, it has drawbacks such as the development device becoming complicated and large.

As one measure to eliminate these drawbacks, a dry developing method was devised in which magnetic carrier is mixed into the toner layer on the outer peripheral surface of the developing roller. A developing sleeve 2 having a magnetic row 21 and for conveying magnetic developer in one direction on its outer circumferential surface, and a developing sleeve 2 located on the upstream side of the developing area in the developer conveying direction (arrow b). A cavity 3 is opened toward the opposite direction and is filled with a magnetic carrier or a mixture of magnetic carrier and toner in advance, and a cavity 3 extends in the axial direction of the developing sleeve 2 within the area covered by the magnetic field of the magnetic roller 1. Toner supply tank 4
and a toner supply means 6 for supplying the toner contained in the toner supply tank 4 through the toner supply slit 5 and into the empty chamber 3. A developing device has been proposed (Japanese Patent Application Laid-open No. 1983-
(See Publication No. 53677).

In this dry type developing device, first, a magnetic developer made of a mixture of magnetic carrier and toner is loaded into a vacant chamber 3, and magnetic toner is loaded into a toner replenishing tank 4. The developer in the empty chamber 3 is circulated and transported in the direction of the arrow C by the rotation of the developing sleeve 2 in the direction of the arrow A and the rotation of the magnetic roller 1 in the direction of the arrow a. The electrostatic latent image carried on the surface of the drum 7 is developed. The magnetic developer remaining on the outer peripheral surface of the developing sleeve 2 after being subjected to development reaches the empty chamber 3 again, where new magnetic toner is supplied and mixed and stirred within the empty chamber 3, and then subjected to development again. be done. The magnetic toner stored in the toner supply tank 4 is transferred to the toner supply slit 6 side formed by the first partition plate 8 and the second partition plate 9 by the rotation of the toner supply blade 6 in the direction of arrow d. The toner is conveyed to the toner supply slit 5 and rises due to the pulsating action based on the rotation of the magnetic roller 1 in the direction of the arrow a.
The air is supplied into the empty room 3 through the air. The supply amount corresponds to the amount by which the toner in the empty chamber 3 is reduced.

Problems to be Solved by the Invention However, when a developing device having such a configuration is operated for a long time, the toner concentration of the magnetic developer held and conveyed on the outer peripheral surface of the developing sleeve 2 may become uneven. This occurs, and the toner density is particularly low near both ends of the developing sleeve 2 in the axial direction. At this time, the magnetic carrier flows out into the toner supply tank 4 and the blowing toner mixes into the empty chamber 3.
It was confirmed that there was no l″i.

The overall unevenness in toner density is considered to be due to the fact that the area of the empty chamber 3 that accommodates the magnetic developer and mixes and stirs it is outside the magnetic field area of the magnetic roller 1. In other words,
The upper layer of the magnetic developer mixed and stirred while flowing in the direction of arrow e in the empty chamber 3 is not held by the magnetic force of the magnetic roller 1, and the upper layer of the magnetic developer is mixed and stirred while flowing in the direction of the arrow e in the empty chamber 3. It flows in the axial direction of the developing sleeve 2. Therefore, it is considered that the magnetic developer in the empty chamber 3 is a mixture of magnetic carriers non-uniformly in the axial direction of the developing sleeve 2, resulting in uneven toner concentration.

Also, the decrease in toner concentration near both ends is due to the decrease in the toner concentration near both ends.
When the magnetic developer is loaded and operated, the magnetic developer flows in the direction of the arrow θ while contacting the second partition plate 9, and the magnetic developer flows in the direction of the arrow θ in FIG. As shown in the figure,
Portions 9 near both ends of the second partition plate 9 in the axial direction of the developing sleeve 2
Since a large amount of magnetic developer flows in 2L, the initial pressure of the magnetic developer stored in the vicinity of both ends of the axial cavity 3 of the developing sleeve 2 is increased and the fluidity is increased. This is thought to be due to the fact that the toner supply slit 5 has a reduced supply path, and the supply path of the toner supply slit 5 becomes narrow due to the collected magnetic developer, resulting in a shortage of toner supply.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a developing device that can achieve uniformity and stabilization of mixing and agitation of the developer conveyed to the developing area and stabilization of the supply performance of the developer.

Means for Solving the Problems The present invention provides a first developer which is located within the magnetic field area of the magnetic roller on the upstream side of the layer thickness regulating member in the developer conveying direction and which stores the developer conveyed by the developing roller. a chamber, and a distal end portion extending in the axial direction of the sleeve on the upstream side of the first developer chamber and having a generally convex shape protruding into the first developer chamber;
a guide plate forming a supply path for supplying the developer to the first developer chamber; and a second developer chamber having a developer supply means for storing the developer and supplying the stored developer into the supply path. A developing device equipped with

In other words, the first developer chamber disposed within the magnetic field area of the magnetic roller and the second developer chamber having the developer supply means are connected to a regulating plate and a sleeve disposed to form the first developer chamber. Electrical communication is established only through a developer supply path formed by a guide plate provided with a substantially convex tip extending in the axial direction of the developer chamber and protruding into the first developer chamber. As the amount of developer in the first developer chamber decreases, the developer stored in the second developer chamber is transferred to the first developer through the developer supply path by the conveying force of the developer supply means and the magnetic field action of the magnetic roller. The materials are supplied into the room, where they are mixed and agitated by the holding and conveying force of the developing roller.

In this case, since the developer in the first developer chamber is always attracted toward the sleeve surface by the magnetic force of the magnetic roller, it is mixed and stirred uniformly throughout and is prevented from flowing in the axial direction of the sleeve. . Therefore, when a developer containing a magnetic carrier is used, the magnetic carrier can be held uniformly in the axial direction of the sleeve, thereby preventing uneven toner concentration.

In addition, the developer in the first developer chamber near both ends of the sleeve in the axial direction can protrude into the first developer chamber, and by forming a small protrusion height near both ends of the closed guide plate, the developer can be moved toward the surface of the sleeve. Since the guide plate does not inhibit the flow of the developer to the developer, the fluidity is improved, sufficient mixing and agitation can be obtained, and the supply of the developer is not obstructed, so that the developer supply path is secured.

In the developer supply path, the developer still receives pressure (supply force) in the direction of the first developer chamber by the developer supply means, and also receives pressure in the direction of the first developer chamber due to the magnetic field effect caused by the rotation of the magnetic roller. (supply force), the developer in the first developer chamber that is about to flow out toward the first developer chamber is suppressed and prevented from flowing out.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIG. 1, a developing device includes a rotatable magnetic roller 11 having a plurality of magnetic poles contained in a cylinder 1o of the developing device, and a sleeve 12 made of a non-magnetic material and rotatable relative to the magnetic roller 11. The roller 13 is arranged close to the surface of the photoreceptor drum. In addition, minute irregularities are formed on the outer circumferential surface of the sleeve 12 by sandblasting or the like on the mesh 240. The developer is held and conveyed on the outer circumferential surface of the sleeve 12 in the direction indicated by the arrow A by the rotation of the magnetic roller 11 in the direction of the arrow a and the rotation of the sleeve 12 in the direction indicated by the arrow. In order to regulate the layer thickness of the developer on the surface of the sleeve 12 that is held and conveyed in the direction into the developing area, the sleeve 1 is located upstream of the developing area A in the developer conveying direction.
A layer thickness regulating member 14 made of a magnetic material is fixedly installed on the support member 16 so as to maintain a predetermined gap 11 between the two surfaces.

The support member 15 is made of a non-magnetic material and is attached to the cylindrical body 10. The regulating plate 16 is a layer thickness regulating member 1 in the developer transport direction.
4 is disposed extending in the axial direction of the sleeve 12 so as to face the surface of the sleeve 12 on the upstream side, and the regulating plate 16 and the housing 10. A first developer chamber 17 that stores the developer conveyed by the developing roller 13 into the magnetic field area of the magnetic roller 11 by the developing roller 13, the layer thickness regulating member 14, and the supporting member 15.
is formed. The guide plate 18 extends in the axial direction of the sleeve 12 on the upstream side of the first developer chamber 17 in the developer conveyance direction, has a tip portion protruding into the first developer chamber 17, and has a distal end protruding from the surface of the sleeve 12 and the regulating plate. 16 with a predetermined gap 12. e3, and is attached to the bottom of the housing 10. A developer supply path 19 is formed near the lower end of the regulation plate 16 and the guide plate 18 . Regulation plate 1
6 and the guide plate 18 are made of, for example, non-magnetic metal plates.

The guide plate 18 has a substantially convex tip that protrudes into the first developer chamber 17, for example, as shown in FIG. The shape is slanted, and the protrusion height H near the center and at both ends is
H2 is formed to become H,)H2.

A second developer chamber 2o for storing developer is provided behind the developer supply path 19, and a third developer chamber 21 is provided above the second developer chamber 2o. In the second developer chamber 20, there are installed a developer supply means for stirring the developer and supplying it into the developer supply path 19, and a developer amount detection means for detecting when the developer is empty. has been done.

The developer supply means is composed of a rotatably supported agitation supply member 22 using a vane plate or a crank rod, etc., and the agitation supply member 22 is rotatable at a constant speed in the direction of arrow d. The developer in the second developer chamber 20 is stirred and conveyed to the developer supply path 19 side. The developer amount detection means has an arm 23 that is pivotally supported in a swingable manner, and is movable back and forth between a first position Y1 at the upper part of the second developer chamber 20 and a second position Y2 at the lower part thereof. Detection member 2 provided
4, an agitation supply member 22 that periodically touches the lower end of the arm 23 and serves as a regulating means for forcibly moving the detection member 24 to the first position Y1, and a stirring supply member 22 that urges the detection member 24 to the second position. It is composed of a biasing means that properly balances the weight of the arm 23 and the detection member 24, and a detection means that uses an appropriate switching means to detect that the detection member 24 is located at the second position Y2. When the inside of the developer chamber 20 becomes empty, it is displayed on the outside. Stirring supply member 22
The lower end of the arm 23 that comes into regular contact with the rotation of the
In order to enable the arm 23 to swing even when the stirring supply member 22 rotates in the direction opposite to the direction of the arrow d, it is formed into a substantially arc shape, so that it can swing smoothly regardless of the rotation direction of the stirring supply section 22. The arm 23 is pivotally supported in a position where it can be rotated.

A swingably supported partition plate 26 is provided between the second developer chamber 2o and the third developer chamber 21, and a developer supply path 26 is formed between the partition plate 25 and the bottom surface of the housing 10. It is formed.

The swinging of the partition plate 25 is caused by the heavy pressure of the developer in the third developer chamber 21, the weight of the partition plate 25, and the agitation supply member 22 and the partition plate 2.
This is performed by periodically bringing the protrusions 26 & provided on the protrusions 26 & 5 into contact with each other.

Next, the operation of the developing device having the above configuration will be explained.

After the device is pre-operated, the third developer chamber 21 and the second developer chamber 2o are loaded with magnetic toner developer. At this time, only the magnetic gear may be loaded into the first developer chamber 17. In the case of one-component development using only a magnetic toner developer without using a magnetic carrier, step 3. The developer may be loaded into the first developer chamber 17 through the second developer chambers 21 and 20. In this state, the electrostatic latent image can be developed by this apparatus.

Here, the developer is held and conveyed on the outer peripheral surface of the sleeve 12 in the direction indicated by the arrow by the rotation of the magnetic roller 11 in the direction of the arrow a and the rotation of the sleeve 12 in the direction indicated by the arrow. First developer chamber 1
7, the magnetic carrier and the magnetic toner are mixed and stirred, and each is triboelectrically charged. As a result of this mixing and agitation, the magnetic carrier, which is the developer, and the magnetic toner are constantly integrated at a mixing ratio within a certain range at this point, and a magnetic brush made of the developer is reliably formed in the development area A. be done. The magnetic brush formed here is the photoreceptor drum 7.
The electrostatic latent image on the surface is developed and visualized. After being exposed to development, the developer (Li) remaining on the outer peripheral surface of the sleeve 12 reaches the first developer chamber 17 again, where it is mixed and stirred with the developer supplied from the second developer chamber 20. The developer in the first developer chamber 17 is constantly attracted toward the surface of the sleeve 12 by the magnetic force of the magnetic roller 11. The developer near the surface is held and conveyed in the direction of the arrow A, and the developer that remains after being regulated by the layer thickness regulating member 14 flows in the direction of the arrow θ and is uniformly mixed and stirred as a whole, while being transported in the axial direction of the sleeve 12. In addition, the developer near both ends of the sleeve 12 in the axial direction is prevented from flowing into the first developer chamber 17, as shown in FIG. Due to the small size, the obstruction to the flow of the developer circulating from the direction of the arrow e toward the surface of the sleeve 12 is reduced, so that fluidity is improved and sufficient mixing and agitation can be obtained. The developer circulating in the surface direction can be prevented from coming into contact with and gathering near the tip of the guide plate 18, and the developer supply path 19 can be secured without interfering with the supply of developer.

The developer is supplied to the first developer chamber as follows.

The developer stored in the second developer chamber is conveyed to the developer supply path 19 side by the rotation of the agitation supply member 22 in the direction of arrow d, and is pulsated due to the rotation of the magnetic roller 11 in the direction of arrow Δ. As a result, the developer rises along the surface of the guide plate 18 on the regulating plate 16 side, and is supplied into the first developer chamber 17 through the developer supply path 19 .

The supplied amount corresponds to the amount by which the developer in the first developer chamber 17 is reduced.

The developer stored in the third developer chamber 21 is moved upward by contact with the agitation supply member rotating the partition plate 25.
After the contact is released, the partition plate 25 moves downward due to the weight of the partition plate 25 and the heavy pressure of the developer in the third developer chamber 21, causing the developer to flow into the second developer chamber 2o through the developer supply path 26. will be replenished. The supply amount is replenished in accordance with the internal pressure of the second developer chamber 20, and a space is always maintained in the upper layer of the second developer chamber 20.

As the developer in the third developer chamber 21 runs out and the developer in the second developer chamber 2o decreases, the detection member 24
When the oscillation becomes large and the detection member 24 is moved down and oscillated to the second position Y2, the second and third developer chambers 20, 21
Empty developer inside is detected and displayed on the outside.

As a developing bias, a DC voltage may be applied to the sleeve 12 based on a normal method, or an AC voltage may be superimposed thereon, or the sleeve 12 may be grounded.

By the way, when this device was used, no unevenness in toner concentration occurred in the axial direction of the sleeve 12 even after long-time operation. Furthermore, even when the device was operated with the sleeve 12 tilted at an angle of about 57,100 m in the axial direction, the toner density could be maintained within a certain range to ensure high quality images. This is because the developer in the first developer chamber 17 is always attracted toward the surface of the sleeve 12 under the magnetic force of the magnetic roller 11, so that it is uniformly mixed and stirred as a whole, and the developer is This is because the flow of magnetic carriers, especially the flow of magnetic carriers, is suppressed. Further, the developer supply path 19 is filled with developer, and this developer is moved toward the first developer chamber 17 by the magnetic field action caused by the rotation of the agitation supply member 22 of the developer supply means and the rotation of the magnetic roller 11. This is because the pressure (supply force) is applied, so that the outflow of the developer, especially the outflow of the magnetic carrier, into the second developer chamber 2° is suppressed. Furthermore, the developer supplied to the first developer chamber 17 is not immediately supplied onto the surface of the sleeve 12, but is mixed and stirred within the first developer chamber 17, so that the developer is sufficiently charged. The application of the developing bias works effectively, and high-quality images without capri are obtained. By maintaining the toner concentration in the first developer chamber 1 constant, the toner concentration of the developer forming the magnetic brush in the large development area is always constant. In the present invention, only the consumed amount of the developer in the first developer chamber 17 is supplied to the first developer chamber 17.
The toner concentration within is approximately constant. Therefore, automatic toner concentration control based on volume control is possible.

Effects of the Invention As is clear from the above description, according to the present invention, there is a first developer chamber that stores the developer conveyed by the developing roller within the magnetic field area of the magnetic roller, and a first developer chamber in the developer conveyance direction. 1 Extending in the axial direction of the sleeve on the upstream side of the first developer chamber, and having a substantially convex tip protrude into the first developer chamber, the developer is disposed in the first developer chamber. By providing a guide plate forming a supply path for supplying the first developer and a second developer chamber having a developer supply means for storing the developer and supplying the stored developer into the supply path, the first developer The developer in the developer chamber can be mixed and stirred uniformly throughout, ensuring sufficient electrification of the developer and preventing unevenness in toner concentration due to developer flow in the axial direction of the sleeve, especially the flow of magnetic carrier. . In addition, the fluidity of the developer in the first developer chamber near both ends of the sleeve in the axial direction is improved, sufficient mixing and agitation can be obtained, and the obstruction of developer supply by the developer in the first developer chamber is removed. can. Furthermore, since the developer supply pressure is always applied to the developer supply path, it is possible to reliably prevent the developer in the first developer chamber from flowing out into the second developer chamber. As a result, it is possible to obtain copied images of good quality over a long period of time.

Furthermore, it is possible to improve the resistance to slope when installing the device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a developing device in an embodiment of the present invention;
Figure 2 is a cross-sectional view of X2-X2 in Figure 1, and Figure 3 +-i.
A cross-sectional view showing the configuration of a conventional developing device, FIG.
, -X is an explanatory view showing a cross-sectional view in the direction of arrows and showing a flowing state of the developer. 7... Photosensitive drum, 10... Housing,
11...Magnetic roller, 12...Sleeve, 14...Layer thickness regulating member, 15...Supporting member, 16...Regulating plate, 17...First developer chamber, 18...Guidance plate, 19...
-Developer supply path, 20...Second developer chamber, 22
・・・・・・Agitation supply member. Name of agent: Patent attorney Toshio Nakao and 1 other person/2
-m-sleeve/4---May? J'4 Kin'1゜'6-Supporting member/6---Present Shome and lδ-11 Inner slope/, 3/'7 Fig. 2 Fig. 3 Fig. 2/γ 5

Claims (1)

[Claims] A developing device that includes a rotatable magnetic roller with multiple magnetic poles and a non-magnetic sleeve that is rotatable relative to the magnetic roller.Developer is held on the surface of the sleeve and circulated in one direction. a roller, a layer thickness regulating member disposed facing the sleeve surface and regulating the layer thickness of the developer held and conveyed on the developing roller; a first developer chamber extending in the axial direction of the sleeve and accommodating the developer conveyed by the developing roller; and a first developer chamber facing the sleeve surface to form the first developer chamber. a regulating plate extending in the axial direction of the sleeve on the upstream side of the first developer chamber and having a distal end protruding into the first developer chamber; a guide plate forming a developer supply path for supplying the developer; and a guide plate for storing the developer;
and a second developer chamber having a developer supply means for transporting the developer to the developer supply path side while stirring the developer,
The first developer chamber is disposed within the magnetic field region of the magnetic roller, and the tip of the guide plate that protrudes into the first developer chamber is formed into a substantially convex shape, A developing device in which the protruding height of the guide plate protruding from the sleeve is smaller near both ends than near the center in the axial direction of the sleeve.