JPH0619309A - Developing device - Google Patents

Abstract

PURPOSE:To improve the stirring efficiency of developer, newly replenished toner and recycled toner and to rapidly and surely uniformize the distribution of toner concentration. CONSTITUTION:This developing device is constituted of a main stirring member 103 which stirs and supplies the developer to a developer carrier arranged in a developing device housing 101, an auxiliary stirring member 104 which takes in the developer refluxed from the main stirring member 103 and the replenished toner, mixes and stirs them, discharges them in a direction perpendicular to the shaft of a developing means, and supplies them to the member 103, a partition plate 107 which partitions the device to a developing chamber 100A having the developer carrier and the member 103, and a toner carrying chamber 100B having the member 104, and is provided with a developer outflow aperture part through which the developer is allowed to flow out of the member 1014 to the member 103 and a developer inflow aperture part 107B through which the developer is refluxed to the member 104. The developer inflow aperture part of the partition plate 107 is set at a lower position than the height of the upper surface of the developer being stirred in the developing chamber 100A and at a higher position than the height of the upper surface of the developer being stirred in the chamber 100B.

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 concentration detection.

[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 of 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 composed of a plurality of permanent magnets inside thereof 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 carrier by the rotation of the developing sleeve to develop the electrostatic latent image. .

That is, the developer, which is formed as a brush of a 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 according to the rotation of the developing sleeve, and the developer scraping plate. Alternatively, the magnetic field is separated from the surface of the developing sleeve by the repulsive magnetic field, and is mixed and stirred by the stirring blade with new toner supplied in a fixed amount from the toner container to prepare for new development.

In a 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 supply device. Is designed to fall and be replenished.

[0006]

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, it is necessary to keep the inside of the developing device. It is necessary that the toner concentration of the developer is constantly made uniform and kept constant. Further, when the density sensor detects a change in toner density, it is necessary to immediately replenish the toner with new toner to efficiently and quickly maintain the toner density in the developer at a uniform and constant density.

As a related technique of a developer stirring means and a toner concentration detection sensor in a conventional developing device, there is disclosed in Japanese Patent Laid-Open No. 58-1.
No. 94068, No. 50-155235, and No. 52-130335 are disclosed.

The toner density of the developer in the developing device varies depending on the original image density, continuous copying, and the like, and the developer volume changes. The toner concentration of the developer must be detected to replenish the toner.

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

[0010]

A developing device of the present invention which achieves the above object comprises a first stirring member for stirring and supplying a developer to a developer carrying member arranged in a housing of the developing device.
The second refluxing developer from the first stirring member and the replenishment toner supplied from the toner replenishing member are taken in, mixed and stirred, and discharged in the direction perpendicular to the axis of the developing means and supplied to the first stirring member. A stirring member, a developing chamber having the developer carrying member and the first stirring member, and a toner carrying chamber having the second stirring member are partitioned from each other, and the developer is transferred from the second stirring member to the first stirring member. And a partition plate provided with a developer inflow opening for allowing the developer to flow back to the second stirring member, wherein the developer inflow opening of the partition plate is provided. The section is set at a position lower than the upper surface height of the developer being stirred in the developing chamber and higher than the upper surface height of the developer being stirred in the toner transport chamber.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of an image forming portion of an electrophotographic copying machine equipped with a developing device according to the present invention.

The photoconductor drum 1 has a photoconductive layer formed on the outer peripheral surface of a grounded metal cylinder, and rotates in the arrow (clockwise) direction in conjunction with optical system exposure scanning.

Around the photosensitive drum 1, a charging electrode 2, a charging erasing LED 3, an exposure image forming unit 4, a developing device 10, a transfer electrode 5, a separating electrode 6, a separating claw 7, a cleaning device 8, an afterimage erasing (before charging) An exposure device 9 is sequentially arranged.

An image carrier (hereinafter referred to as a photoconductor drum) 1 having an image forming photoconductive layer on its outer peripheral surface rotates clockwise, and first, a surface of the photoconductor drum 1 is made uniform by a charging electrode 2. After being charged, image exposure is performed with the light flux L from the slit exposure optical system to form a latent image on the exposure image forming unit 4 on the photosensitive drum 1. The latent image on the photoconductor drum 1 is developed into a visible toner image when passing through the developing device 10.

A transfer electrode 5 and a separation electrode 6 are provided below the photosensitive drum 1, and the toner image is formed at the transfer electrode 5 on a copy sheet P fed from an upstream side sheet feeding device (not shown). Is transferred, and then the copy paper P is separated from the photoconductor drum 1 at the separation electrode 6 and then sent to a fixing device (not shown) on the downstream side to fix the toner image, and then discharged to the outside of the device. .

On the other hand, the residual toner T1 on the photosensitive drum 1 after the transfer reaches the cleaning device 8 and is wiped by the cleaning blade 81. And cleaning blade 81
The toner T1 that falls off by its own weight from the surface of the photosensitive drum 1 that has been wiped by is received by the screw conveyor 82 arranged below the blade 81, and is delivered to the toner recycling device 20. The toner recycling device 20 is a device for circulating the toner T1 from the cleaning device 8 to the developing device 10.

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 unit 100, a developing roller 102 consisting of a developing sleeve and a magnet, a main stirring member 103 having a plurality of stirring blades, and a spiral screw-shaped auxiliary stirring member 104 are rotatably supported. Has been done. Further, a spike control 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 in which a toner cartridge 130 accommodating replenishment toner is detachably attached and detached, and a ladder for discharging the toner accumulated at the bottom of the casing 111 upwards. Wheel 113, ladder chain 114, toner scraping member 11
5, a toner unloading unit, and a toner remaining amount detecting sensor 117.
Also, a toner supply member 116 is provided.

When the portion of the photosensitive drum 1 on which the electrostatic latent image is formed reaches a position (developing region) near the developing roller 102 of the developing portion 100, toner is stored in the charge holding portion on the photosensitive drum 1. 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 detecting sensor 106 detects this, and the toner unloading means in the toner replenishing unit 110 causes the replenishment toner to move upward. The toner is replenished by the toner replenishing member 121, the toner replenishing member 121 rotates, the toner drops from the opening of the casing 111, and the auxiliary stirring member 104 of the developing unit 100 located below rotates and agitates and conveys the developer.
The mixture is agitated and mixed by 3, part of which is supplied to the developing roller 102 and the other part of which is supplied to the auxiliary stirring member 104.

The main stirring member 103 has 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, the developer in the developing unit 100 is mixed and stirred, and the developer is supplied onto the developing roller 102.

FIG. 2 is a sectional view of the developing section 100 according to the present invention taken along the line AA in FIG. 1, and FIG. 3 is an exploded view showing the main parts of the developing device according to the present invention. In these figures, the arrows indicate the moving directions of the developer and the replenishment toner.

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 left spiral screw portion 104B in the forward direction and a right spiral screw portion 104C in the opposite direction in which the developer conveying direction is different. By driving and rotating both the forward and reverse spiral screws 104B and 104C, the developer is transported and concentrated from both directions b and c in the drawing to the vicinity of the center which is the boundary between the spiral screws.

The forward left spiral screw portion 10
A four-bladed main paddle part 104PA arranged in the direction orthogonal to the axis of rotation 104A is integrally formed near the center of the boundary between the right spiral screw 104C and the direction opposite to 4B. In addition, a plurality of two-blade-shaped sub paddle portions 104PB that form 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 left spiral screw portion 104B, and a plurality of other right spiral screw portions 104C are provided. In the same manner, a plurality of sub paddle parts 104PC are integrated at the locations (four locations in the figure). The main paddle portion 104PA and the sub paddle portions 104PB and 104PC transfer the developer conveyed during rotation of the rotary shaft 104A, in a direction (normal direction) a perpendicular to the rotary shaft.
To each.

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 portion 104B of 04 is further extended to the left, and the toner T1 collected by the cleaning device 8 is carried into the screw end portion 104D via the toner recycling device 20.

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

Above the auxiliary stirring member 104, the toner replenishing member 121 is driven and rotated at appropriate times, and the toner cartridge 1
An appropriate amount of new replenishment toner T2 in 20 drops, and an auxiliary stirring member
Supply over 104.

A partition plate 107 is fixedly provided on 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. 1 by the partition plate 107. Has been converted. That is, the developing chamber 100A on the left side including the main stirring member 103 and the toner transport chamber 100B on the right side including the auxiliary stirring member 104 are divided.

As shown in FIG. 3, the partition plate 107 has a large gate-shaped developer outlet opening 107A formed substantially in the lower center. Main paddle portion 104P of the auxiliary stirring member 104
The developer discharged from the A and the plurality of sub paddle portions 104PB in the normal direction of the rotation axis passes through the opening 107A of the partition plate 107 and is discharged in the a direction to be conveyed to the main stirring member 103 and stirred. The opening 107A is the main paddle portion 104 at the center.
PA and a plurality of width paddle parts 104PB, 104PC on the left and right sides thereof
Is formed in an open shape over a portion corresponding to the length including.

Above the opening 107A of the partition plate 107,
Plural developer penetrating openings 107B, 107C that penetrate the ellipse
Has been drilled. These plural openings 107B, 107C
Is a plurality of sub paddle parts 10 provided on the left and right spiral screw parts 104B and 104C of the auxiliary stirring member 104.
They are provided above 4PB and 104PC in the developer transport direction. Therefore, the developer that has flowed back from the main stirring member 103 passes through the plurality of openings 107B and 107C of the partition plate 107, and the left and right spiral screw portions 1 of the auxiliary stirring member 104.
Sub paddle parts 104PB, 10 downstream of the opening of 04B, 104C
Flowed into 4PC.

FIG. 4 is an enlarged cross-sectional view of a main part of the developing device according to the present invention. In the figure, an inflow opening 107B (107C) provided on the upper part of the partition plate 107 is provided in the developing chamber even at the developer height at the minimum toner concentration within the toner concentration control range.
The height is set so that it can flow into the toner transfer chamber 100B from 100A and is higher than the standard height of the developer accommodated in the toner transfer chamber 100B. Therefore, the inflow of the partition plate 107 is such that the developer storage height during stirring in the developing chamber 100A on the left side of the drawing is always kept higher than the developer storage height during stirring in the toner transport chamber 100B on the right side. The upper side of the height of the opening 107B (107C) is set.

FIG. 5 (A) is a partial side view of the partition plate 107, and FIG. 5 (B) is the development when the upper side position (H dimension) of the inflow opening 107B (107C) of the partition plate 107 is changed. FIG. 6 is a characteristic diagram obtained by an experiment result showing a relationship between a developer stirring time and a developer inflow amount.

In FIG. 5B, the horizontal axis represents the developer stirring time (sec), and the vertical axis represents the inflow opening 107B (107).
The amount (g) of the developer jumped into the toner transfer chamber 100B on the right side from C) is shown. These curves A, B, C, D
Is a state in which the developer stirring time by driving rotation of the main stirring member 103 and the auxiliary stirring member 104 is 30 seconds, 60 seconds, 90 seconds, and the developer inflow amount (g) after the change changes due to the change of the H dimension. Show. Here, the experimental value of the developer inflow amount is the accumulated weight of the developer flowing out from the through hole of the toner transport chamber 100B from which the toner concentration detection sensor 106 is removed.

The curve A shown in FIG. 5B is the opening 107B, 1
FIG. 11 is a characteristic diagram in which the amount (g) of developer inflow into the toner transport chamber 100B is measured every time a stirring time elapses when the upper side height of 07C is set to H = 7 mm. A curve B is a characteristic diagram when H = 11 mm is set. These curves A and B show that the developer inflow increases almost linearly with the passage of stirring time,
It shows that a substantially constant amount of developer flows in every second. A curve C of H = 3 mm and a curve D of H = 15 mm have a low slope, and after 60 seconds, the developer inflow amount becomes almost zero per second, indicating that no inflow has occurred. This indicates that if the developer inflow openings 107B and 107C are too high or too low, the developer does not flow back into the toner transport chamber 100B, resulting in poor stirring.

In the dimension range of H = 7 to 11 mm, the developer storage height of the developing chamber 100A on the left side is equal to the inflow opening 107B.
At a position higher than the upper side of (107C), the developer storage height of the toner transfer chamber 100B on the right side is kept at the same height H as the upper side, and is kept stable. Then, at this height H, the screw portion and the paddle portion of the auxiliary stirring member are stirred while 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 above H dimension (Hl≈H), the partition plate 10
The height of the developer in the toner transport chamber 100B is regulated by the seven inflow openings 107B (107C) and is always maintained at a constant height.

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 carrying chamber 100B.
Accurately detects the toner density and supplies an appropriate amount of toner to stably control the toner density in the developer within a predetermined range. In the meantime, it is possible to obtain stable high-quality copying with almost no difference in image quality.

Next, the operation of the developing device of the present invention will be described with reference to FIGS. 6 and 2. FIG. 6 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 replenishing screw 1 of the toner replenishing section 110
The new replenishment toner T2 supplied and dropped from 16 to the right chamber of the developing unit 100 in the direction of the arrow e is supplied near both shaft ends of the auxiliary stirring member 104, and the left and right spiral screw portions 104B having mutually opposite propulsive forces. , 104C from both ends thereof in the directions b and c as shown by the arrows, are gathered toward the central portion of each, and the recycled toner T1 supplied to the screw end portion 104D of the auxiliary stirring member 104 is also left. It is merged onto the spiral screw portion 104B, and during this period, it is mixed with a reflux developer described later and conveyed. The reflux developer, the new replenishment toner T2, and the recycled toner T1 are mixed and stirred by the spiral screw portions 104B and 104C to be uniformized, and are conveyed toward the central portion on the downstream side.

The mixed developer is conveyed toward the center by the left and right spiral screw portions 104B and 104C, and a part of the developer is fed to the sub paddle portions 104PB and 104P on the downstream side.
It is radially discharged by C, passes through the outflow opening 107A in the lower part of the partition plate 107, and is supplied to the main stirring member 103 (direction a). Further, the other part of the mixed developer is further conveyed to the central part by the spiral screw parts 104B and 104C, and is radially scattered by the main paddle part 104PA, and the developing part 100 is discharged from the developer outflow opening 107A of the partition plate 107. Is fed into the developing chamber 100A on the left side of (a direction).

Main paddle portion 104P of the auxiliary stirring member 104
A, the main paddle portion 1 when the developer passes from the sub paddle portions 104PB and 104PC to the developer outflow opening 107A of the partition plate 107.
A toner concentration detection sensor 106 arranged below 04PA detects the toner concentration of the developer.

The developer which has 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 developing area.

During the stirring by the main stirring member 103, the developer sent in the direction d shown in the drawing passes through the plurality of developer inflow openings 107B, 107C of the partition plate 107 and again the auxiliary stirring member 10
Reflux to the spiral screw parts 104B and 104C of No. 4.

That is, each opening 107 of the partition plate 107.
The reflux developer, the new replenishment toner T2, and the recycled toner T1 that have passed B and 107C are b and c by the left and right spiral screw portions 104B and 104C of the auxiliary stirring member 104.
A part of the developer is radiated in the direction normal to the rotation axis by the auxiliary paddle parts 104PB and 104PC on the downstream side while being conveyed from the direction indicated by the double-headed arrow toward the central part, and the opening 107A of the partition plate 107.
Flow through the main agitating member 103 and the remaining developer and replenishment toner are discharged to both spiral screw parts 104B and 104C.
Is transported to the central part by the main paddle part 104PA
The developer circulation is repeated in the direction of arrow a.

By these developer circulation paths, the new toner, the recycled 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 agitated 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.

The developer inflow openings 107A, 107B, 107C of the partition plate 107 are not limited to those in the above embodiment, and the number of arrangements, the shape, the width, the size, the arrangement position, etc., of the toner density may be different. It can be appropriately selected depending on the installation of the detection sensor and the like.

[0051]

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

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming unit of an electrophotographic copying machine including a developing device according to the present invention.

FIG. 2 is a sectional view taken along the line AA of the developing device according to the present invention.

FIG. 3 is an exploded view showing main parts of the developing device.

FIG. 4 is an enlarged cross-sectional view of a main part of the developing device according to the present invention.

FIG. 5 is a characteristic diagram showing a relationship between a developer stirring time and a developer inflow amount when the height of the developer inflow opening of the partition plate is changed.

FIG. 6 is a perspective view illustrating a developer circulating state of the developing device according to the present invention.

[Explanation of symbols]

 1 Photoreceptor Drum 8 Cleaning Device 10 Developing Device 20 Toner Recycling Device (Toner Recycling Means) 100 Developing Unit 100A Developing Chamber 100B Toner Transfer Chamber 101 Casing (Developing Device Housing) 102 Developing Roller 103 Main Stirring Member (Developer Stirring Member) 104 Auxiliary stirring member (developer transport part) 104B Left spiral screw part 104C Right spiral screw part 104D Screw end part 104PA Main paddle part 104PB, 104PC Sub paddle part 106 Toner concentration detection sensor 107 Partition plate 107A Developer outflow opening 107B , 107C Developer inflow opening 110 Toner replenishment part a, b, c, d, e, f Developer conveying direction T1 Residual toner (recycled toner) T2 Newly replenished toner

Claims (1)

[Claims] 1. A first agitating member for agitating and supplying the developer to a developer carrying member arranged in a housing of the developing device, and a developer and a toner replenishing member refluxed from the first agitating member. A second stirring member that takes in the supplied replenishment toner, mixes and stirs it, discharges it in the direction perpendicular to the axis of the developing means, and supplies it to the first stirring member; and the developer carrying member and the first stirring member. The developing chamber having the second stirring member is partitioned from the developing chamber and the toner transport chamber having the second stirring member, and the developing agent outflow opening for causing the developer to flow from the second stirring member to the first stirring member and the second stirring member are developed. A developing device comprising a partition plate provided with a developer inflow opening for refluxing the developer, wherein the developer inflow opening of the partition plate is lower than the upper surface height of the developer being stirred in the developing chamber. Developer being stirred at the position and in the toner transport chamber. The developing device is set at a position higher than the height of the upper surface of the developing device.