JPH05341648A - Developing device - Google Patents

Abstract

PURPOSE:To realize the rapid and efficient stirring and circulation of developer and to uniformize supply distribution by providing plural spiral screw parts and a fin for scattering the developer. CONSTITUTION:A developing roller 102 is rotated by driving force from a driving source, and simultaneously a main stirring member 103 and an auxiliary stirring member 104 are rotated through gears G0 and G1 and through gears G2 and G3, respectively. Then, new toner dropping to be supplied in the right chamber of a developing part from the toner replenishing screw of a toner replenishment part is driven forward by the spiral screws 104B and 104C of the member 104 having driving force reverse to each other in directions shown by arrows (a) and (b) from both ends of the screws and gathered in the center part, while it is mixed with recycled developer and carried. The recycled developer including the toner carried to the center part is radially scattered by the fin part 104A, and fed to the left chamber of the developing part from a developer outflow aperture part 107A below the center part of a partition plate.

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. It relates to agitation of the 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, JP-B-56-5102, JP-B-50-27333, JP-A-63-
Each publication of No. 34567 is disclosed.

[0007]

The toner concentration in the developer is extremely important for obtaining a good quality image, and in order to obtain a stable image, it is necessary to keep the toner concentration constant all the time. .. Further, when the density sensor detects a change in toner density, it is necessary to immediately replenish an appropriate amount of new toner to efficiently and promptly make the toner density in the developer uniform and constant.

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

[0009]

SUMMARY OF THE INVENTION A developing device of the present invention which achieves the above-mentioned object, comprises 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 developer. A first stirring member for stirring and supplying to the developer carrying member, and a second stirring member for mixing and stirring the developer refluxed from the first stirring member and the replenishment toner and supplying to the first stirring member. A developing device comprising: a member; and a developing device housing that supports the developer carrier, the first stirring member, and the second stirring member by arranging respective rotation axes in parallel with each other. The agitating member has a forward spiral screw portion and a reverse spiral screw portion, which have different developer conveying directions, arranged adjacent to each other, and the developer is concentrated at the developer concentration portion at the boundary between the forward and reverse screw portions. A special feature is that a fin part that emits in the normal direction is provided. It is an.

Further, the developing device of the present invention is characterized in that a plurality of sets of the forward and reverse direction screw parts and fin parts are arranged on the shaft of the second stirring member.

[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.

3 is a sectional view of the developing section 100 according to the present invention taken along the line AA in FIG. 2, FIG. 4 (A) is a side view of the partition plate, and FIG. 4 (B) is a side view of the auxiliary stirring member. ..

The main stirring member 103 comprises a plurality of elliptical plate-shaped stirring blades 103A fixed to a rotating shaft 103B, and a gear G1 fixed to the shaft end portion is developed by a gear G0 by a driving force from a developing roller 102. It is rotated in the opposite direction to the roller 102, 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 has a fin portion 104A having a plurality of blades formed substantially in the center of the shaft, and a right spiral screw portion 104B and a left spiral screw portion 104C are formed on both sides of the shaft. There is. 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. Further, the right spiral screw portion 104B of the auxiliary stirring member 104
Is further extended to the left, and the toner collected by the cleaning device 14 is carried into the screw end portion 104D through the recycling tube 16.

A toner concentration detecting sensor 106 is installed directly below the fin portion 104A at the substantially central portion of the auxiliary stirring member 104, that is, at the bottom portion at the substantially central portion of the casing (housing) 101.

Above the auxiliary stirring member 104, the toner replenishing screw 116 is driven and rotated at appropriate times, and a new amount of new toner in the toner cartridge 120 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 the left and right chambers shown in FIG. 2 by the partition plate 107. Has been converted.

As shown in FIG. 4 (A), the partition plate 107 has a gate-shaped developer discharging opening 107A at the lower center thereof.
However, rectangular penetrating developer inflow openings 107B and 107C are formed at two locations near both ends thereof.

Next, the operation of the developing device of the present invention will be described with reference to FIGS.

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

In the developing device having the above structure,
By 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 the chamber 16 to the right of the developing unit 100 and dropped, is propelled by the screws 104B and 10C of the auxiliary stirring member 104, which have mutually opposite propulsion forces, from both ends thereof in the directions a and b as shown by the arrows. The reflux developer containing the toner transported to the central portion is collected in the central portion, and is mixed with the reflux developer to be described later, and is conveyed to the fin portion 10.
The toner is scattered radially by 4A and is fed into the chamber on the left side of the developing section 100 from the developer outflow opening 107A below the central portion of the partition plate 107.

When the developer passes from the fin portion 104A near the center of the conveying and stirring member 104 to the developer outflow opening 107A of the partition plate 107, the toner concentration detecting sensor 106 arranged below the fin portion 104A is Detect the toner density of the developer.

The developer that has passed through the opening 107A is mixed with the developer refluxed from the developing area by the stirring blade 103A of the rotating main stirring member 103, stirred, homogenized 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 C direction shown in FIG. 5 passes through the developer inflow opening 107B of the partition plate 107 and returns to the auxiliary stirring member 104 again. A circulation path is formed which proceeds in the direction of arrow a.

Further, the developer sent in the d direction of the main stirring member 103, after stirring, passes through the other developer inflow opening 107C, is returned to the auxiliary stirring member 104 again, and is circulated in the direction of arrow b. To form.

By these two developer circulation paths, the new toner and the developer stored in the developer 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, and is conveyed in the arrow e direction and is conveyed in the arrow a direction. 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.

FIG. 5 shows another embodiment of the developing device according to the present invention, FIG. 5 (A) is a side view of the partition plate, and FIG. 5 (B) is a side view of the auxiliary stirring member. Regarding the reference numerals used in these drawings, the parts having the same functions as those in the above-mentioned embodiment are designated by the same reference numerals. Further, the points different from the above embodiment will be described.

The auxiliary stirring member 1040 according to the present invention has fin portions 1041, 1042, 1043 at a plurality of positions on its rotation axis and a right spiral screw portion 1044a1 for conveying the developer in the forward direction (a1, a2, a3 in the drawing). , 1044a2, 1044a3,
Left spiral screw part 10 that conveys developer in the opposite direction
45b1, 1045b2, 1045b3.

The right spiral screw portion 1044a1 and the left spiral screw portion 1045b1 are connected to both sides of the fin portion 1041 on the left side in the drawing to form one set.
Similarly, the fin portion 1042 near the center of the drawing and the right spiral screw portion 1044a2 and the left spiral screw portion 1045b2 on both sides thereof form one set. Further, the fin portion 1043 on the right side in the figure and the right spiral screw portion 1044a3 and the left spiral screw portion 1045b3 on both sides form one set.

The toner replenished on the right spiral screw portion 1044a1 and the circulated developer are conveyed in the direction of the arrow a1 by the propelling force of the screw, and at the same time, the toner and the developer on the left spiral screw portion 1044b1 move to a1. They are conveyed in the direction of the arrow b1 facing each other and are gathered together in the fin portion 1041. Here, the developer is scattered in the direction orthogonal to the rotation axis by the four-sheet paddle (blade) shown in the figure. When the developer passes through the central fin portion 1042, the toner concentration detection sensor 106 detects the toner scattering in the developer.

Similarly, both screw portions 1044a in the central portion
The toner and the developer collected by 2, 1045b2 are scattered in the direction perpendicular to the axis (normal line) by the paddle of the fin portion 1042. Also in the fin portion 1043 on the right side of the drawing, the toner and the developer conveyed from the directions of the arrows a3 and b3 are scattered in the direction perpendicular to the axis (normal line).

The toner and the developer scattered from the three places of the auxiliary stirring member 1040 pass through the developer outflow opening 107A under the partition plate 107, and the main stirring member of the developing unit 100.
The auxiliary stirring member 1 is supplied to 103, passes through a plurality of developer inflow openings 107D formed in the partition plate 107, and again.
Reflux over 040 and repeat circulation.

[0051]

In the developing device of the present invention, a plurality of spiral screw parts wound in opposite directions, and the developer at the position where the developer gathers in the middle of the spiral screw parts are aligned in the direction normal to the four-axis axis. Since it is provided with the fins that scatter, the developer can be stirred and circulated quickly and efficiently, and the developer can be uniformly distributed and supplied to the main stirring member and the developing roller.

[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 an auxiliary stirring member and a partition plate of the developing device.

FIG. 5 is a side view showing another embodiment of the auxiliary stirring member and the partition plate of the developing device according to the present invention.

[Explanation of symbols]

6 Photosensitive Drum 10 Developing Device 100 Developing Unit 101 Casing (Case) 102 Developing Roller 103 Main Stirring Member (First Stirring Member) 104,1040 Auxiliary Stirring Member (Second Stirring Member) 104A, 1041,1042,1043 Fin portion (paddle) 104B, 1044a1,1044a2,1044a3 Right spiral screw portion 104C, 1045b1,1045b2,1045b3 Left spiral screw portion 104D Screw end portion 106 Toner concentration detection sensor 107 Partition plate 107A Developer outflow opening 107B, 107C, 107D Developer inflow opening 110 Toner supply section 116 Toner supply screw 120 Toner cartridge a, b, c, d, e, a1, a2, a3, b1, b2, b3 Developer transport direction

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Takenobu Kimura 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 replenishment toner that have flowed back from the first stirring member, supplies the developer to the first stirring member, the developer carrying member, the first stirring member, and the first stirring member. In the developing device, a developing device housing configured to support the rotating shafts of the two stirring members in parallel with each other is provided, wherein the second stirring member includes a forward spiral screw portion having different developer conveying directions. The reverse spiral screw portion is disposed adjacent to each other, and a fin portion for discharging the developer in the normal direction is provided at the developer concentration portion at the boundary portion between the forward and reverse screw portions. Developing device. 2. The developing device according to claim 1, wherein a plurality of sets each including a screw part and a fin part in the forward and reverse directions are arranged on the shaft of the second stirring member.