JPH063951A - Developing device - Google Patents

Abstract

PURPOSE:To improve the stirring efficiency of a developer in a developing device, fresh replenished toner and recycled toner, to quickly uniformize the concentration distribution of toner in the developer, and to improve the responsiveness of the control of a toner concentration. CONSTITUTION:An auxiliary stirring member 104 is composed of spiral screw parts 104B and 104C carrying the developer in an axial direction and paddle parts 104PA, 104PB, and 104PC connected to one end of the spiral screw parts and discharging the developer in the normal direction of a rotary shaft, and constituted so as to shield a part corresponding to the paddle part of the auxiliary stirring member in an opening groove 122 provided along a developing width on the lower part of a toner replenishing room holding a toner replenishing member 121 with a shield member 126, so that replenished toner dropped and supplied from the nonshielded opening part of the toner replenishing room can be supplied to the spiral screw parts except the paddle part of the auxiliary stirring member.

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 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.

As a developer stirring means in a conventional developing device, there are JP-A-58-194068, JP-A-50-155235, and JP-A-52-13033.
No. 5 publications are disclosed. Further, Japanese Patent Application Laid-Open No. 1-161382 is disclosed as a related technology of the toner replenishing device.

[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, 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, it is necessary to replenish new toner immediately after the density sensor detects a change in toner density 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]

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.
A second stirring member that mixes and stirs the developer and the replenishment toner that have flowed back from the first stirring member, and a toner that drops and supplies the replenishment toner to the second stirring member. A developing device comprising a replenishing member, wherein the second agitating member is connected to a spiral screw part for conveying the developer in the axial direction and one end of the spiral screw part, and the developer is discharged in the direction normal to the rotation axis. Of the opening groove provided along the developing width in the lower part of the toner replenishing chamber for holding the toner replenishing member and corresponding to the paddle part of the second agitating member by the shielding member. The toner is configured to be shielded, and the replenishment toner dropped and supplied from the non-shielding opening portion of the toner replenishing chamber is supplied to the spiral screw portion other than the paddle portion of the second stirring member. .

Further, the developing device of the present invention is characterized in that the non-shielding opening portion of the toner replenishing chamber is provided at a position corresponding to the upstream side of the developer transport of the paddle portion of the second stirring member. It is a thing.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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. An original D is set on the surface of the original platen glass 1 and is pressed and covered with an original pressing plate (platen cover) 2. After that, a 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 integrated with the light source 3.
Through the moving mirrors M2 and M3 mounted on the carriage 4 which moves at the same time, and is converged by the imaging lens 5 and further through the fixed mirror M4 to form an image on the surface of the photosensitive drum 6 which is an image carrier. 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 direction of the arrow (clockwise) 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.

In this 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 before an optical image is formed. 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. A positive charge is left, and an electrostatic latent image corresponding to the image of the original is formed 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 stored in the paper feeding cassette 20 is conveyed through the first paper feeding roller 21, the second paper feeding roller 22 and the guide plate, and is temporarily moved by the third paper feeding roller 23 and the stopper 24. After being stopped, the toner image is further fed in synchronization with the rotation of the photoconductor drum 6, reaches the peripheral surface of the photoconductor 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 to transfer the toner image onto the transfer paper P.

The transfer paper P on which the toner image is transferred is then peeled off from the surface of the photosensitive drum 6 by the separation electrode 12 and the separation claw 13 and is further conveyed to the fixing device 25 where it is heated by a heating roller. After being heated and fixed, the sheet is discharged by the sheet discharge roller 26 and placed on the sheet 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 unit 100.
And a toner supply unit 110.

Inside the casing 101 of the developing section 100, a developing roller 102 including 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 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 for accommodating replenishment toner is detachably attached and detached, and a ladder for carrying out 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 121 is provided.

A high voltage for bias applied to the developing roller 102 in developing and a toner concentration detecting 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 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 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 detecting sensor 106 detects this, and the toner unloading means in the toner replenishing unit 110 raises the replenishment toner 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.

FIG. 3 is a sectional view of the developing section 100 according to the present invention taken along the line AA in FIG. 2, and FIG. 4 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 main stirring member 103 comprises a plurality of elliptical plate-shaped stirring blades 103A fixed to a rotary 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.

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 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 right spiral screw part 10 in the forward direction
A four-bladed main paddle portion 104PA arranged in the direction orthogonal to the axis of rotation 104A is integrally formed near the center of the boundary between the left spiral screw portion 104C and the opposite direction of 4B. Further, a plurality of two blade-shaped auxiliary paddle portions 104PB forming an axis right angle to the rotating shaft 104A are provided at a plurality of locations (four locations shown in the drawing) of the one spiral screw portion 104B, and a plurality of locations of the other spiral screw portion 104C ( Similarly, a plurality of sub paddle portions 104PC are integrated at four locations in the drawing). Main paddle part 104PA above, sub paddle part 1
The 04PB and 104PC respectively discharge the conveyed developer in the direction (normal direction) a perpendicular to the rotation axis 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 104B of 04 is further extended to the left, and the toner collected by the cleaning device 14 passes through the recycling tube 16 and the screw end 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 detection sensor 106 is installed on the bottom of the substantially central portion.

Above the auxiliary agitating member 104, the toner replenishing member 121 is driven and rotated at appropriate times, and the toner cartridge 1
An appropriate amount of new toner in 30 is dropped and supplied onto the auxiliary stirring member 104.

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 left and right chambers shown in FIG. 2 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. 4, 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 A and the plurality of sub paddle portions 104PB 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,
Plural rectangular penetrating developer inflow openings 107B are formed. All of the plurality of openings 107B are provided on the left and right spiral screw portions 104 of the auxiliary stirring member 104.
B and 104C have a plurality of sub paddle parts 104PB and 104PC
Are provided above in the respective developer transport directions. Therefore, the developer recirculated from the main stirring member 103 is separated by the partition plate 1.
After passing through the plurality of openings 107B of 07, the left and right spiral screw portions 104B and 104C of the auxiliary stirring member 104 are introduced into the sub paddle portions 107PB and 107PC downstream of the openings.

FIG. 5 is an enlarged cross-sectional view of a main part of the developing device according to the present invention. FIG. 6 is a partial perspective view near the toner supply member of the developing device.

The space above the toner supply member 121 is a toner supply chamber 120. In the toner supply chamber 120, the toner stored in the cartridge storage chamber 112 is scooped up by the toner scraping member 115 by the operation of the ladder chain 114, and the upper part of the boundary wall between the cartridge storage chamber 112 and the toner supply chamber 120. The toner is supplied into the toner replenishing chamber 120 through the opening 116.

In the lower part of the toner supply chamber 120, as shown in FIG.
As shown in FIGS. 5 and 6, an opening groove 122 is formed along the developing width direction (the rotation axis direction of the toner replenishing member 121). The opening groove 122 is closed by the toner supply member 121. Further, a mouth end member 124 having an elastic seal member 123 and a mouth end member 125 made of an elastic plate are installed on the lower side of the cylindrical surface of the toner supply member 121. When the toner replenishing member 121 is driven and rotated in the direction of the arrow by the detection signal from the toner concentration detecting sensor 106, the toner in the toner replenishing chamber 120 is caught in the spiral groove of the toner replenishing member 121 and pushes the mouth end member 125 open. While falling, it is supplied onto the auxiliary stirring member 104.

The opening groove 122 provided in the lower portion of the toner replenishing chamber 120 along the developing width direction has a plurality of portions corresponding to the main paddle portion 104PA and the sub paddle portions 104PB and 104PC of the auxiliary stirring member 104. It is blocked by the shielding member 126. The shielding member 126 is made of polyethylene terephthalate (polyester) PET film and is fixed to the peripheral edge of the opening groove 122 of the casing 111.

That is, the replenishment toner in the toner replenishing chamber 120 is dropped only by the rotation of the toner replenishing roller 121 from the opening portion of the opening groove 122 which is not blocked by the shielding member 126, and the auxiliary stirring below is performed. Main paddle part 1 of member 104
04PA and the auxiliary paddles 104PB and 104PC are provided on the spiral screw parts 104B and 104C, and the spiral screw parts 104B and 104C that rotate further cause
The developer is conveyed in the b and c directions, respectively, and is mixed with the refluxing developer, and a part of the developer is added to the downstream side sub paddles 104PB and 104P.
C is discharged in the normal direction (a) of the rotation axis, and the other developer is conveyed further downstream to the main paddle section 104 at the center.
It is discharged by the PA in the direction of the normal line to the rotation axis (a).

Next, the operation of the developing device of the present invention will be described with reference to FIGS. 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 replenishing screw 1 of the toner replenishing section 110
The new toner supplied from 16 to the chamber on the right side of the developing unit 100 from the direction of the arrow e falls to the paddles 104P of the auxiliary stirring members 104.
A, 104PB, 104PC are respectively supplied to the upstream side, and are propelled from both ends by left and right screw parts 104B, 104C having mutually opposite propulsion forces in the directions b and c as shown by the arrows, and are gathered in the central part. During this period, the reflux developer containing the toner transported to the central portion while being mixed with the later-described reflux developer is radially scattered by the main paddle portion 104PA, and the developer flows out below the central portion of the partition plate 107. It is fed into the developing chamber 100A on the left side of the developing unit 100 through the opening 107A (direction a). In addition, the sub paddle parts 104PB, 104PC
Also, a part of the developer is discharged in the a direction.

Main paddle portion 104PA of the auxiliary stirring member 104
When the developer passes from the sub paddle parts 104PB and 104PC to the developer outflow opening 107A of the partition plate 107, the main paddle part 104P
A toner concentration detection sensor 106 arranged below A 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 developing area.

During 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 of the partition plate 107 and again the spiral screw portion of the auxiliary stirring member 104. Reflux to 104B and 104C.

The reflux developer and the replenishment toner which have passed through the respective openings 107B of the partition plate 107 are b, c by the left and right spiral screw portions 104B, 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 and the developer stored in the developing section 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.

Further, the toner collected from the cleaning device 14 is introduced into the screw end portion 104D of the auxiliary stirring member 104 which rotates through the recycle tube 16, and the arrow f →
The developer is conveyed in the b direction and merges with the developer conveyed in the c direction shown by the arrow, and during this period, the main paddle portion 104PA and the sub paddle portion 1
It is discharged by 04PB, 10PC, passes through the opening 107A, forms the circulation path described above, is uniformly stirred, and is supplied to the developing roller 107.

The shielding member 126 is not limited to the above embodiment, and the number of arrangement, shape, size, position, etc. can be appropriately selected.

[0054]

In the developing device of the present invention, in the process of replenishing toner into the casing of the developing device and agitating and mixing the developer, the toner dropped from the toner replenishing roller is replenished to the paddle portion on the developer agitating roller. By not supplying the toner to the position, it is possible to prevent the toner from flowing out to the developing sleeve side before being sufficiently mixed with the developer, so that the uniformization of the developer can be stably obtained. Further, as a result, the accuracy and responsiveness of toner concentration detection by the toner concentration detection sensor 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 device according to the present invention.

FIG. 4 is an exploded view showing main parts of the developing device.

FIG. 5 is an enlarged cross-sectional view of a main part of the developing device according to the present invention.

FIG. 6 is a partial perspective view of the developing device.

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 Unit 100A Developing Chamber 100B Toner Transport Chamber 101 Casing (Developing Device 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, 104PC Sub paddle part 106 Toner concentration detection sensor 107 Partition plate 107A Developer outflow opening 107B Developer inflow opening 110 Toner replenishment part 111 casing 121 toner replenishing member 120 toner replenishing chamber 122 opening grooves 124, 125 mouth end member 126 shielding member a, b, c, d, e, f developer conveying direction

Claims (2)

[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, the developer refluxed from the first agitating member and the replenishment toner. A developing device comprising a second stirring member for mixing and stirring and supplying the first stirring member to the first stirring member, and a toner replenishing member for dropping and supplying replenishment toner to the second stirring member. A spiral screw portion that conveys the developer in the axial direction, and a paddle portion that is connected to one end of the spiral screw portion and discharges the developer in the normal direction of the rotation axis,
Of the opening groove provided along the developing width in the lower part of the toner replenishing chamber for holding the toner replenishing member, the portion corresponding to the paddle portion of the second stirring member is configured to be shielded by the shielding member. A developing device characterized in that replenishment toner dropped and supplied from a non-shielding opening of a replenishment chamber is supplied to a spiral screw portion other than a paddle portion of a second stirring member. 2. The developing device according to claim 1, wherein a non-shielding opening portion of the toner replenishing chamber is provided at a position corresponding to a developer carrying upstream side of a paddle portion of the second stirring member. apparatus.