JPH05341645A - Developing device - Google Patents

Abstract

PURPOSE:To improve the efficiency of stirring developer in a developing device, newly replenished toner and recycled toner, to rapidly uniformize toner concentration distribution in developer and to improve responsiveness in the control of toner concentration. CONSTITUTION:This developing device is constituted of a main stirring member 103 stirring and supplying the developer to a developer carrier, an auxiliary stirring member 104 mixing and stirring the developer recycled from the member 103 with the replenished toner and supplying it to the member 103 again, and a partition plate fixed between the members 103 and 104 so as to divide the inside of the developing device housing 101 to a developing chamber and a toner replenishing chamber. An outflow aperture part 107A to cause the developer discharged from the chamber 104 to flow out to the member 103 is provided below the partition plate, and an inflow aperture part to reflux the developer from the member 103 to the member 104 is formed above the partition plate. Then, the upper side of the inflow aperture part is set to regulate the developer in the toner replenishing chamber provided with the member 104 to specified height.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing an electrostatic latent image formed on an image bearing member by a developer by an electrophotographic recording system or an electrostatic recording system, and more particularly to a developing device. The present invention relates to stirring and conveying of developer and toner replenishment.

[0002]

2. Description of the Related Art Generally, in an electrostatic image forming apparatus such as an electrophotographic copying machine, an electrostatic latent image on a charge carrier (photoreceptor drum, etc.) is converted into a visible toner image in a developing device, which is then converted into a visible toner image. A copy image is formed by transferring and fixing on a recording paper.

Conventionally, as a method for developing an electrostatic latent image formed on a photosensitive drum, a two-component developer containing a mixture of toner and a magnetic carrier or a one-component developer consisting of a magnetic toner is used, and a magnetic brush is used. A lot of development is performed by the developing device. In a magnetic brush developing device, a developing roller composed of a non-magnetic cylindrical developing sleeve and a magnetic roll consisting of a plurality of permanent magnets inside the developing sleeve is arranged at a fixed position with respect to an image carrier. The developer magnetically attracted to the peripheral surface of the developing sleeve is conveyed to the developing area facing the image bearing member by the rotation of the developing sleeve to develop the electrostatic latent image. ..

That is, the developer, which is formed as a brush of the magnetic brush on the magnetic pole on the outer peripheral surface of the developing sleeve and is used for the development, is carried on the developing sleeve as the developing sleeve rotates, and the developer scraping plate. Alternatively, the toner is separated from the surface of the developing sleeve by the repulsive magnetic field, and the stirring blade mixes and stirs with new toner supplied in a fixed amount from the toner container to prepare for new development.

In the developing device using the above-mentioned two-component developer, when copying is repeated, the toner in the developing device is consumed. Therefore, the toner is replenished in an amount corresponding to the consumed amount, and the toner carrier is always used. If the mixing ratio (toner density) is not kept constant, copying with an appropriate density will not be performed. Therefore, the mixing ratio of toner and carrier in the developing device is detected and the toner replenishing device automatically uses the toner. Are designed to fall and be replenished.

As a developer stirring means in a conventional developing device, there are JP-A Nos. 58-194068, 50-155235 and 52-13033.
Each publication of No. 5 is disclosed.

[0007]

The toner concentration in the developer supplied to the developer carrying member is extremely important for obtaining a good quality image, and in order to obtain a stable image, the inside of the developing device is required. It is necessary to make the toner concentration of the developer to be always uniform and constant. Further, when the density sensor detects a change in toner density, it is necessary to replenish new toner immediately to make the toner density in the developer uniform and constant.

An object of the present invention is to provide a developing device which can meet this demand.

[0009]

SUMMARY OF THE INVENTION A developing device of the present invention which achieves the above, is to stir a developer carrier which is arranged to face an image carrier which forms an electrostatic latent image and which forms a developer layer, and a developer. A second stirring member for supplying the toner to the developer carrying member, and a second stirring member for mixing and agitating the developer and the replenishment toner refluxed from the first stirring member and again supplying them to the first stirring member. A member, a developing device housing that supports the developer bearing member, the first stirring member, and the second stirring member by arranging the respective rotation axes in parallel, the first stirring member, and the second stirring member A developing device which is fixedly provided between the developing device housing and a partition plate which divides the interior of the developing device housing into a developing chamber and a toner replenishing chamber, wherein the second stirring member is provided below the partition plate. In addition to providing an outflow opening for allowing the discharged developer to flow out to the first stirring member, Toner in which an inflow opening for flowing the developer from the first agitating member to the second agitating member is formed at an upper portion of the partition plate, and an upper side of the inflow opening is provided with the second agitating member. It is characterized in that the developer in the replenishing chamber is set to a predetermined height.

Further, even when the upper side of the inflow opening of the partition plate in the developing device of the present invention is the developer height at the minimum toner concentration within the toner concentration control range, the second agitating member in the toner replenishing chamber. It is characterized in that it is set to a position where is not exposed.

[0011]

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of an electrophotographic copying machine equipped with a developing device according to the present invention. The schematic structure and function of the copying machine will be described with reference to FIG.

A document table glass 1 is provided on the upper surface of the main body of the copying machine. The original D is set on the surface of the original platen glass 1 and is pressed and covered by the original pressing plate (platen cover) 2. Then, the copy start switch is operated.
Performs relative exposure scanning of the document D, and the slit light flux L of the optical image of the document D is moved by the moving mirror M1 which is integrated with the light source 3.
Through the moving mirrors M2 and M3 mounted on the carriage 4 that moves relative to each other at the same time. To be done.

The photosensitive drum 6 is formed by forming a photoconductive layer such as selenium or OPC on the outer peripheral surface of a grounded metal cylinder.
It rotates in the arrow (clockwise) direction in conjunction with the above exposure scanning.

Around the photosensitive drum 6, a strip electrode 7, a charge erasing LED 8, an exposure image forming section 9, a developing device 10, a transfer electrode 1
1, a separation electrode 12, a separation claw 13, a cleaning device 14, and an afterimage erasing (pre-charging exposure) device 15 are sequentially arranged.

Before the optical image is formed on the photosensitive drum 6, the photoconductive layer is, for example, positively and uniformly charged by the band electrode 7 to which a high DC voltage is applied. When the photoconductive layer in this state receives the light image of the document D, the conductivity of the portion receiving the light becomes high, the charged electric charge of the portion escapes to the metal cylinder, and the dark portion depends on the degree of lightness and darkness. Positive charges are left to form an electrostatic latent image corresponding to the image of the original on the surface of the photoconductive layer. Next, the electrostatic latent image on the photosensitive drum 6 is subjected to the developing action of the developing device 10 to be visualized as a toner image.

The photosensitive drum 6 carrying a visible toner image reaches the transfer portion.

On the other hand, the transfer paper P accommodated in the paper feed cassette 20 is conveyed through the first paper feed roller 21, the second paper feed roller 22 and the guide plate, and is temporarily moved by the third paper feed roller 23 and the stopper 24. After being stopped, the toner image is further fed in synchronization with the rotation of the photosensitive drum 6 and reaches the peripheral surface of the photosensitive drum 6, and the toner image is transferred at the transfer portion. That is, the transfer paper P supplied to the transfer portion is brought into close contact with the surface of the photosensitive drum 6, and the transfer electrode 11 receives a discharge having a polarity opposite to that of the toner, and the toner image is transferred onto the transfer paper P.

The transfer paper P on which the toner image has been transferred is then peeled off from the surface of the photosensitive drum 6 by the separating electrode 12 and the separating claw 13 and is further conveyed to the fixing device 25 where it is heated by a heating roller. It is heated and fixed, discharged by the paper discharge roller 26, and placed on the paper discharge tray 27.

On the other hand, the photosensitive drum 6 from which the transfer paper P is separated
Cleans the toner remaining on the surface with the cleaning device 14, removes the residual charge with the pre-charge exposure device 15, and returns to the original state. After that, the next image formation is repeated by the same operation as the above process.

FIG. 2 is a sectional view of the image forming process unit of the copying machine.

The developing device 10 is roughly classified into a developing section 100.
And a toner supply unit 110.

Inside the casing 101 of the developing section 100, a developing roller 102 composed of a developing sleeve and a magnet, a main stirring member (first stirring member) 103 having a plurality of stirring blades,
A spiral screw-shaped auxiliary stirring member (second stirring member) 104 is rotatably supported. Further, a bristling regulating plate 105 is provided above the developing roller 102, and a toner concentration detection sensor 106 is provided below the auxiliary stirring member 104.

Inside the casing 111 of the toner replenishing section 110, a cartridge accommodating chamber 112 for detachably attaching and detaching the toner cartridge 120 for accommodating the replenishing toner, and a ladder for carrying out the toner accumulated at the bottom of the casing 111 upward. Wheel 113, ladder chain 114, toner scraping member 11
5 toner discharge means and toner supply screw 116
Further, a toner remaining amount detection sensor 117 is provided.

A high-voltage bias current applied to the developing roller 102 for development and a toner concentration detection sensor 10
6, developing device, such as each detection current of the toner residual detection sensor 117
Electric power transmitted and received to and from the main body of the copying machine is supplied from a power supply unit and a control unit.

When the portion of the photosensitive drum 6 on which the electrostatic latent image is formed reaches the proximity position (developing region) of the developing roller 102 of the developing portion 100, toner is stored in the charge holding portion on the photosensitive drum 6. It is attracted by electrostatic force to form a toner image.

When the amount of toner in the developing unit 100 decreases and the toner concentration decreases due to repeated copying, the toner concentration detection sensor 106 detects this, and the toner unloading means in the toner replenishing unit 110 raises the replenishment toner. The toner is replenished by the toner replenishing screw 116 and is dropped from the opening of the casing 111 by the rotation of the auxiliary stirring member 104 of the developing unit 100 located below to be stirred / conveyed with the developer and further stirred by the main stirring member 103. Mixed, part of the development roller 102
Then, the other part is replenished on the auxiliary stirring member 104.

FIG. 3 is a sectional view of the developing unit 100 according to the present invention taken along the line AA in FIG. 2, FIG. 4A is a side view of the partition plate, and FIG. 4B is a side view of the auxiliary stirring member. 4C is a side view of the toner concentration detection sensor.

The main stirring member 103 comprises a plurality of elliptical plate-shaped stirring blades 103A fixed to a rotating shaft 103B. A gear G1 fixed to the end of the shaft is developed by a gear G0 by a driving force from a developing roller 102. The roller 102 is rotated in the opposite direction, and the developer in the developing unit 100 is mixed and stirred to supply the developer onto the developing roller 102.

The auxiliary stirring member 104 is provided on the rotating shaft 104A connected to the drive source, the spiral screw portion integrated with the outer periphery of the rotating shaft 104A for conveying the developer, and the spiral screw portion. Paddles 104PA, 104P for discharging the developer in the rotation direction when the roller rotates
B, 104 PC. Further, the spiral screw portion is composed of a right spiral screw portion 104B in the forward direction and a left spiral screw portion 104C in the reverse direction, which are different in the developer conveying direction. By the drive rotation of both the forward and reverse spiral screws 104B and 104C,
The developer is transported and concentrated near the center, which is the boundary between both spiral screws.

The forward spiral screw portion 104B
A four-bladed main paddle portion 104PA arranged in the direction orthogonal to the axis of rotation 104A is integrally formed in the vicinity of the center of the boundary with the reverse spiral screw portion 104C. Further, a plurality of two blade-shaped sub-paddle portions 104PB forming an axis right angle with the rotating shaft 104A are provided at a plurality of locations (four locations shown in the figure) of the one spiral screw portion 104B, and a plurality of locations of the other spiral screw portion 104C ( (4 locations in the figure)
Similarly, a plurality of sub paddle units 104PC are integrated respectively. The main paddle section 104PA and the sub paddle section 104P
The B and 104PC respectively discharge the conveyed developer in the direction perpendicular to the rotation axis (normal direction) when the rotation shaft 104A is driven and rotated.

The rotating shaft 104A of the auxiliary stirring member 104 is rotated in the same direction as the main stirring member 103 by the gear G3 via the main stirring member 103 and the intermediate gear G2. In addition, the auxiliary stirring member 1
The right spiral screw part 104B of 04 is further extended to the left side, and the toner collected by the cleaning device 14 passes through the recycling tube 16 and the screw end part 104B.
Carried to D.

Immediately below the main paddle portion 104PA at substantially the center of the auxiliary stirring member 104, that is, the casing (housing) 101.
A toner concentration sensor 106 is installed at the bottom of the substantially central portion.

Above the auxiliary stirring member 104, the toner replenishing screw 116 is driven and rotated at a proper time to drop an appropriate amount of new toner in the toner cartridge 120, and the auxiliary stirring member 1
Supply on 04.

A partition plate 107 is fixed to the casing 101 between the main stirring member 103 and the auxiliary stirring member 104, and the developing unit 100 is divided into the left and right chambers shown in FIG. 2 by the partition plate 107. Has been converted. That is, the left developing chamber 100A including the main stirring member 103 and the right toner replenishing chamber 100B including the auxiliary stirring member 104 are divided.

As shown in FIG. 4 (A), the partition plate 107 has a large gate-shaped developer outlet opening 10 at the lower center thereof.
7A is formed. The developer discharged from the main paddle portion 104PA and the plurality of sub paddle portions 104PB of the auxiliary stirring member 104 passes through the opening 107A of the partition plate 107 and is conveyed to the main stirring member 103 and stirred.

Above the opening 107A of the partition plate 107,
A plurality of rectangular penetrating developer inflow openings 107B, 107C
Has been drilled. Each of the plurality of openings 107B has a right spiral screw 104 of the auxiliary stirring member 104.
It is provided on the upstream side of each of the plurality of sub paddle portions 104PB provided in B in the developer carrying direction a. Partition board in the same way
The plurality of openings 107C of 107 are respectively provided on the upstream side in the developer conveying direction b of the plurality of sub paddle portions 104PC provided on the left spiral screw 104C. Therefore, the developer recirculated from the main stirring member 103 passes through the plurality of openings 107B and 107C of the partition plate 107 and the auxiliary paddle portions downstream of the left and right spiral screw portions 104B and 104C of the auxiliary stirring member 104. It flows into 107PB and 107PC.

FIG. 5 is an enlarged sectional view of the developing device according to the present invention. In the figure, the upper side of the inflow opening 107B (107C) provided in the upper part of the partition plate 107 has an auxiliary stirring member 104 in the toner replenishing chamber 100B even at the developer height at the lowest toner concentration within the toner concentration control range. Is set to a position where is not exposed. Therefore, the developing chamber 100 on the left side of the drawing
The upper side of the inflow opening 107B (107C) of the partition plate 107 is set so that the developer storage height A is always maintained at a position higher than the developer storage height of the right toner replenishing chamber 100B. There is.

FIG. 6A is a partial side view of the partition plate 107, and FIG. 6B is a relationship between the upper side position (H dimension) of the inflow opening 107B (107C) of the partition plate 107 and the toner inflow amount. FIG. 6 is a characteristic diagram obtained from experimental results.

In FIG. 6B, the horizontal axis indicates the inflow opening.
The height of the upper side of 107B (107C) from the reference surface is shown, and the vertical axis shows the amount (g) of the developer that flows into the toner replenishing chamber 100B on the right side from the inflow opening 107B (107C).
Here, the curve A shows a state in which the developer inflow amount (g) after the developer stirring time of 30 seconds due to the driving rotation of the main stirring member 103 and the auxiliary stirring member 104 changes due to the change of the H dimension. Curve B is the result of measuring the stirring time 60 seconds, curve C is 90 seconds, and curve D is the flow rate of each developer after 120 seconds while changing the H dimension. As shown in these characteristic curves, H
The dimension of 7 to 11 mm is the stable range of the developer inflow. In this size range, the developer storage height of the left developing chamber 100A is
At a position higher than the upper side of the inflow opening 107B (107C), the developer storage height of the toner replenishing chamber 100B on the right side is kept at the same height H as the upper side, and is kept stable. Be done. At this height H, the screw portion and the paddle portion of the auxiliary stirring member are stirred in a state of being substantially buried below the developer height H.

In this way, even when the developer in the developing chamber 100A is in a high toner concentration state and the developer storage height (Hh) is much higher than the H dimension (Hh >> H), it is low. Even when the toner concentration state and the developer storage height (Hl) are close to the H dimension (Hl≈H), the partition plate 10
The height of the developer in the toner replenishing chamber 100B is always kept constant by being regulated by the upper side of the inflow opening 107B (107C).

Since the amount of the developer in the toner replenishing chamber 100B becomes constant by keeping the height constant, the toner concentration detecting sensor 106 provided at the bottom of the toner replenishing chamber 100B.
Accurately detects the toner concentration and supplies a proper amount of toner to stably control the toner concentration in the developer within a predetermined range. In the meantime, stable image quality copying with almost no difference in image quality can be obtained.

Next, the operation of the developing device of the present invention will be described with reference to FIGS. 2, 3 and 5. FIG. 7 is a perspective view of a main part of the developing device for explaining the developer circulating state.

In these figures, the arrow indicates the moving direction of the developer.

In the developing device having the above structure,
Due to the driving force from the driving source, the developing roller 102, the main stirring member 103 via the gears G0 and G1, and the auxiliary stirring member 104 via the gears G2 and G3 simultaneously rotate.

Toner supply screw 1 of the toner supply unit 110
The new toner supplied from 16 to the right chamber of the developing unit 100 drops from both ends in the directions a and b as indicated by the left and right screw parts 104B and 104C of the auxiliary stirring member 104 having mutually opposite propulsive forces. The recirculating developer containing toner, which is conveyed to the central portion while being mixed with the recirculating developer described later, is scattered radially by the main paddle portion 104PA and is separated by the partition. Board 107
3 is fed into the left chamber of the developing unit 100 shown in FIG.

From the main paddle portion 104PA near the center of the auxiliary stirring member 104, the developer outflow opening 107A of the partition plate 107 is formed.
When the developer passes through, the toner concentration detection sensor 106 arranged below the main paddle portion 104PA detects the toner concentration of the developer.

The developer having passed through the opening 107A is mixed and stirred with the developer refluxed from the developing area by the stirring blade 103A of the rotating main stirring member 103 to be uniformized and supplied to the developing roller 102. The developer layer thickness is regulated by the upright regulation plate 105, and the developer layer is conveyed to the development area.

On the other hand, during the stirring by the main stirring member 103, the developer sent in the direction c shown in FIG. 3 passes through the plurality of developer inflow openings 107B of the partition plate 107 and again the auxiliary stirring member 104. To form a circulation path that proceeds in the direction of arrow a.

The developer sent in the d direction of the main agitating member 103 is agitated and then the other plurality of developer inflow openings 107.
A circulation connection is formed by passing through C and returning to the auxiliary stirring member 104 again to proceed in the direction of arrow b.

The reflux developer and the replenishment toner that have passed through the openings 107B and 107C of the upstream partition plate 107 are stored in the auxiliary stirring member.
The left and right spiral screw portions 104B and 104C of 104 convey the toner from the directions indicated by the arrows a and b toward the central portion, while the sub paddle portions 104PB and 104PC on the downstream sides cause a part of the developer to rotate in the normal direction of the rotation axis. Is emitted to the main stirring member 103 through the opening 107A of the partition plate 107, and the remaining developer and replenishment toner are discharged to both spiral screw portions 104.
The developer is conveyed to the central portion by B and 104C, where it is emitted by the main paddle portion 104PA and the developer circulation is repeated toward the arrows c and d.

By these developer circulation paths, the new toner and the developer stored in the developing unit 100 are uniformly mixed. Further, even if the toner concentration distribution in the developer in the developing unit 100 becomes non-uniform during the repeated copying process, it can be moved and stirred in the rotation axis direction by the circulation path to uniformly mix the toner. It is possible to solve the problem that the image becomes uneven.

Further, the toner collected from the cleaning device 14 is introduced into the screw end portion 104D of the rotating auxiliary stirring member 104 via the recycle tube 16, is conveyed in the direction of arrow c, and is conveyed in the direction of arrow a. It merges with the developer and passes through the fin 104A and opening 107A near the center,
The two loops of the above-described c → a left circulation path and d → b right circulation path are formed to be uniformly stirred and supplied to the developing roller.

The spiral screw portions 104B and 104C of the auxiliary stirring member 104 and the opening portion 107 of the partition plate 107.
The A, 107B, and 107C are not limited to those in the above embodiment, and the number of arrangements, shapes, dimensions, positions, etc. of these can be appropriately selected.

[0055]

In the developing device of the present invention, the height of the upper side of the developer inflow opening of the partition plate for partitioning the developing chamber and the toner replenishing chamber and the height of the auxiliary stirring member are regulated to assist the development. Since the developer storage height in the toner replenishing chamber including the stirring member is kept constant, the circulation efficiency of the developer is improved, and the accuracy and responsiveness of the toner concentration accuracy are significantly improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a copying machine including a developing device according to the present invention.

FIG. 2 is a sectional view of an image forming process unit of the copying machine.

FIG. 3 is a sectional view taken along the line AA of the developing unit according to the present invention.

FIG. 4 is a side view of each of an auxiliary stirring member, a partition plate, and a toner concentration detection sensor of the developing device.

FIG. 5 is an enlarged sectional view of the developing device according to the present invention.

FIG. 6 is a side view of the partition plate and a characteristic diagram showing the relationship between the H dimension of the partition plate and the developer inflow amount.

FIG. 7 is a perspective view illustrating a developer circulating state of the developing device according to the present invention.

[Explanation of symbols]

 6 Photosensitive drum 10 Developing device 100 Developing section 100A Developing chamber 100B Toner replenishing chamber 101 Casing (housing) 102 Developing roller 103 Main stirring member (first stirring member) 104 Auxiliary stirring member (second stirring member) 104B Right Spiral screw part 104C Left spiral screw part 104D Screw end part 104PA Main paddle part 104PB Sub-paddle part 106 Toner concentration detection sensor 107 Partition plate 107A Developer outflow opening 107B, 107C Developer inflow opening 110 Toner supply section 116 Toner Replenishing screw H Partition plate developer inlet opening top height a, b, c, d Developer transport direction

Front page continuation (72) Inventor Mimoto Nemoto 2970 Ishikawacho, Hachioji City, Tokyo Konica Stock Company

Claims (2)

[Claims] 1. A developer carrying member which is arranged to face an image carrying member which forms an electrostatic latent image and forms a developer layer, and a first stirring member which stirs the developer and supplies the developer to the developer carrying member. A second stirring member that mixes and stirs the developer and the replenishment toner that have flowed back from the first stirring member, and supplies the mixed toner to the first stirring member again; the developer carrier and the first stirring member; A developing device housing that supports the rotating shafts of the second stirring member by arranging them in parallel with each other, and is fixed between the first stirring member and the second stirring member so that the inside of the developing device housing is a developing chamber. And a partition plate that is divided into a toner supply chamber and a partition plate, wherein the developer discharged from the second stirring member flows out to the first stirring member below the partition plate. An outflow opening is provided, and the first stirring member and the second stirring member are provided on the partition plate. An inflow opening for circulating the developer is formed in the stirring member, and the upper side of the inflow opening is set so as to regulate the developer in the toner replenishing chamber in which the second stirring member is disposed to a predetermined height. Developing device. 2. The upper side of the inflow opening of the partition plate does not expose the second stirring member in the toner replenishing chamber even at the developer height at the minimum toner concentration within the toner concentration control range. The developing device according to claim 1, wherein the developing device is set to a position.