JPH0321969A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the biasing phenomenon of developer regardless of the quantity and flowability of the developer by possessing a main agitating means and a circulating carrying means and forming a developer supplying space which supplies circulation developer from the main agitating means to the circulating carrying means by permit ting the space to be different in the axial direction. CONSTITUTION:The device is provided with the main agitating means 6, which agitates the developer D in a developing device main body 2, supplies the developer to the developer carrier 4 and that feeds at part of the developer D to the circulating carrying means 7 and 8, and the circulating carrying means 7 and 8, which mix the circulating developer from the main agitating means 6 with replenished developer, carry the mixed developer in the axial direction of the developer carrier 4 and that returns the developer to the main agitating means 6. The developer supplying space 73, which supplies the circulating developer from the main agitating means 6 to the circulating carrying means 7 and 8 is formed differently in the axial direction. Therefore, the developer is balanced in the axial direction of the developer carrier 4 and the biasing phenomenon of the developer D is eliminated. Thus, the development without shading in the development area is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device, particularly to a developing device used in an electrostatic recording device such as an electrophotographic copying machine.

[Background of the invention]

Conventionally, this type of developing device receives toner supplied from a toner supply hopper provided at one end in the developing width direction of the developing device main body or developer scraped up by a developer stirrer. A first conveying means conveys the toner or developer toward the other end without dropping it little by little, and a first conveying means conveys the toner or developer that has fallen from the first conveying means in the opposite direction to prevent the toner or developer from being biased in one direction. A second conveying means for conveying the liquid is provided to make the distribution amount uniform. (Japanese Unexamined Patent Publications No. 62-55680 and No. 58-163968) The uniformity of the distribution amount is achieved by adjusting the speed (conveying amount) of the spiral screw constituting the first conveying means and the second conveying means. It is important to maintain a balance in the speed (conveying amount) of the spiral screw, and the speeds of the first and second conveying means are adjusted to optimal values determined for each machine.

However, even if the speed of the first and second conveyance means determined for each machine is optimal for one machine, it may not be directly applicable to other machines, making it difficult to unitize or share parts. Met.

In addition, each optimum value changes depending on the amount of developer and its fluidity, so it is necessary to newly consider each time.

[Purpose of the invention]

In view of the above points, the present invention provides a developing device that can eliminate the unevenness of the developer without being affected by the speed balance of the first and second conveyance means, the amount of developer, its fluidity, etc. It is intended to.

[Precepts of invention]

In order to achieve this object, the present invention provides a developing device in which a developer carrier is provided in close opposition to an image carrier, and a developer is attached to an electrostatic latent image on the image carrier to visualize the image. a main stirring means for stirring the developer in the developing device main body and supplying the developer to the developer carrier, and sending a part of the developer to the circulating conveyance means; a circulating developer from the main stirring means and a replenishing developer; and a circulating conveyance means for mixing the developer and conveying it in the axial direction of the developer carrier and further returning it to the main stirring means,
The developer charging gap for charging the circulating developer from the main stirring means to the circulating conveying means is shaped differently in the axial direction.

〔Example〕

Next, the present invention will be described based on embodiments shown in the accompanying drawings. In the following description, the term "developer" refers to a mixture of toner, which is a bipartite developer, and its carrier, and is distinguished from the term "toner".

In FIG. 1, 1 is a photosensitive drum (image carrier), and 2 is a main body of the developing device (casing hereinafter referred to as main body). The main body 2 includes a rotary developing sleeve (developer carrier) 4 with a built-in fixed magnet 3, and a spike regulating plate (blade) 5 that regulates the thickness of the developer D adhering to the developing sleeve 4.
, a main stirring means 6 for the developer D, a first conveyance means 7 for conveying the supplied toner or the developer D in the main body 2 in one direction from one end side to the other end side in the development width direction; A second conveying means 8 that conveys in the opposite direction to the conveying means 7 is provided.

The developing sleeve 4 is disposed close to the photoreceptor drum 1, and has the function of electrostatically adsorbing the developer D onto the photoreceptor drum L and developing the electrostatic latent image as a toner image. .

The main stirring means 6 has a function of stirring and mixing the developer and the supplied toner using a plurality of elliptical stirring plates 62 fixed obliquely to the rotating shaft 6l, and leveling the mixture in the axial direction. These stirring plates 62
A flat plate member 63 is provided between them along the rotating shaft 6l. This flat plate member 63 has the function of sufficiently stirring the developer, scraping up a portion of the developer in the rotational direction of the main stirring means 6, and throwing it into the first conveying means 7.

FIG. 3 is a perspective view of essential parts of this developing device, and FIG. 4 is a schematic sectional view of the developing device.

The first conveyance means 7 is provided between a tray member 7l, a conveyance screw 72 extending vertically through the tray member 7l, and the main stirring means 6 and the conveyance screw 72, and is provided between the tray member 7l and the conveyance screw 72, and is provided between the main stirring means 6 and the conveyance screw 72.
It is separated from the jump regulation plate 10 that regulates the amount of circulation carried in.

The conveyance screw 72 is a metal spiral screw integrally formed by winding and fixing at least one thin metal plate around a metal shaft as shown in FIGS. 2, 3, and 4. It is. Since the conveying screw 72 has a short screw bit and a steep lead inclination angle, the developer conveying force in the axial direction due to the curved surface of the screw is large.

At the bottom of the tray member 7l, a plurality of developer drop holes 71A whose diameters gradually increase in the direction of conveyance are arranged in a row so that the developer D can be dropped in a uniform amount during conveyance. It has become. The drop hole 71B located at the most downstream side in the conveyance direction is formed by the developer D being pushed into one wall of the developing device main body by the conveyance screw 72 (
It is designed to be large enough to prevent overflow of developer from falling (packing).

Further, a partition wall portion 71C is formed in the receiving tray member 7l for introducing the developer D scraped up by the main conveying means 6 from above the conveying screw 72, and the developer is introduced together with the jumping regulating plate 10. A gap 73 is formed.

As shown in FIGS. 3 and 4, the gap width of the developer input gap 73 is narrow (Ql) on the upstream side where the developer is conveyed by the conveyance screw 72 and wide (Q2) on the downstream side.
That is, the gradient shape is set to differ according to the axial direction of the developing sleeve (developer carrier).

Upstream of the developer conveyance side of the conveyance screw 72, an inlet for replenishing new toner T and an inlet for recycled toner are provided.

A conveying screw 8l of the second conveying means 8 is provided in a chamber surrounded by a recess of the developing device main body 2 below the tray member 7l of the first conveying means 7. The conveying screw 8l is made of resin, has a coarse screw pitch, and has a small lead inclination angle, so that the toner conveying force in the axial direction is small and the toner conveying force in the direction perpendicular to the axis is large.

Further, a toner replenishing device for replenishing new toner T into the developing device main body 2 is connected and provided diagonally above the developing device main body 2.

The toner replenishing device includes a lid l2 connected to the developing device main body 2 and housing a toner replenishing container l1, a toner replenishing roller l3 having a spiral screw, a hopper 14 housing the toner T, a vibration plate 15, and a partition. It is composed of a plate l6.

Next, the operation of the developing device according to the present invention will be explained.

The new toner T stored in the hopper l4 of the toner replenishing device is supplied by a toner concentration control means (not shown) in fixed amounts at appropriate times through the replenishment opening at the bottom of the hopper 14 through the opening 1 of the partition plate l6 by driving rotation of the toner replenishing roller l3.
The toner is supplied to the upstream side of the conveyance screw 72 of the first conveyance means 7 through 6A, and mixed with the developer by the conveyance screw 72.

The conveying screw 72 carries the replenishing new toner T and the toner that is stirred in the developing device body 2 by the main stirring means 6 and thrown up, passing through the developer injection gap 73 formed by the jump regulating plate IO. The falling developer D and the recycled toner meet, are mixed along the entire length of the conveying screw 72, and are conveyed downstream along the inside of the tray member 7l as shown by the arrow.

In the developer transport and mixing process by the transport screw 72,
Each drop hole 71A provided near the downstream side of the tray member 7l.
71B causes the developer D to fall downward.

However, the amount of developer D that is circulated and conveyed from the main conveyance means 6 to the conveyance screw 72 is regulated by the developer input gap 73 having a gradient gap, and a large amount is conveyed from the downstream side of the conveyance screw 72. It looks like this. Therefore, in the axial direction of the developer carrier of the first conveying means 7, the amount of circulation of the developer D carried in from the input gap 73 and the amount of developer discharged from the drop hole 71B are approximately the same. is set to . Note that the drop hole 71B has the role of allowing the above-mentioned amount of developer to flow out and replenishing new toner and recycled developer to escape and fall downward so that they do not overflow on the downstream side of the tray member 7l, and so that the developer is not pushed in on the downstream side. to do.

The drop hole 71A of the saucer member 7l. The mixed developer falling from 71B is scattered onto the conveying screw 8l of the second conveying means 8 on the lower side. By the clockwise rotation of the conveyance screw 8l, the mixed developer is conveyed toward the front side in the figure (downstream side of conveyance of the conveyance screw 81), and passes over the partition wall 2A at the bottom of the apparatus main body 2 in the direction of the main stirring means 6. The stirring plate 62 and flat plate member 63 of the main stirring means are carried out.
is stirred and homogenized by the rotation of the developing sleeve 4, and is attracted to the fixed magnet 3 in the developing sleeve 4 and rotated, and the spike regulating plate (
After passing through the blade (blade) 5, it is sent to a developing area close to the photoreceptor drum l.

Note that the above embodiments can be modified in various ways based on the technical idea of the present invention. For example, it is possible to adopt an appropriate feeding mechanism other than a spiral screw for the first and second conveying means, and the receiving tray member of the first conveying means may be replaced with another structure that performs the same function. It is possible.

Furthermore, although the above embodiments have been described using an apparatus using a two-part type developer as an example, the present invention may also be applied to a one-part type developing apparatus.

〔Effect of the invention〕

As described above, in the developing device of the present invention, the developer introduced from the main agitating means to the first conveying means is controlled by jump control in which the developer introduction opening gap is different according to the axial direction of the developer carrier. By regulating the amount of developer returned from the first conveyance means to the main agitation means via the second conveyance means by the plate, it is possible to replenish the amount of developer returned to the main agitating means without being affected by the amount of new toner or recycled toner. It is possible to evenly balance the particles in different directions and eliminate unbalanced development of the developer. Therefore, it is possible to provide a developing device that can perform uniform development in the developing area, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a front cross-sectional view of a developing device according to the present invention, FIG. 2 is a plan cross-sectional view of the developing device, FIG. 3 is a perspective view of the developer circulation conveyance section of the developing device, and FIG. 4 is a cross-sectional view of the developer. FIG. 2 is a schematic cross-sectional view of the developing device showing the relationship between charging and circulating conveyance. 1... Image carrier (photosensitive drum) 2... Developing device main body (casing) 4... Developing sleeve (developer carrier) 6... Main stirring means 7... First conveying means 8 ...Second conveyance means lO...Jumping regulation plate 11...Toner supply container l3...Toner supply roller 14...Hopper-l
6... Partition plate 71... Receiver member 71B... Drop hole 72... Conveying screw 8l... Conveying screw T... Replenishing new toner 16A. 16B...Opening 71A...Developer drop hole 71G...Partition wall 73...Developer input gap D...Developer

Claims (4)

[Claims] (1) In a developing device in which a developer carrier is provided in close opposition to the image carrier and the developer is applied to the electrostatic latent image on the image carrier to make it visible, the developer in the main body of the developing device is A main stirring means that stirs and supplies the developer to the developer carrier and sends a part of the developer to the circulating conveyance means; and a main stirring means that mixes the circulating developer from the main stirring means with the replenishment developer and supplies the developer to the developer carrier. and a circulation conveyance means for conveying the developer in the axial direction of the carrier and further returning it to the main stirring means, and a developer injection gap for feeding the circulating developer from the main stirring means to the circulation conveyance means varies according to the axial direction. A developing device characterized in that it is formed as follows. (2) The circulation conveying means includes a first conveying means that conveys in one direction of the shaft, and a second conveying means that is disposed below the first conveying means and conveys in the opposite direction to the first conveying means. 2. The developing device according to claim 1, further comprising means. (3) the first conveying means is configured with a spiral screw extending vertically through the receiving tray member, and narrows the developer input gap on the upstream side of the developer conveyed by the spiral screw;
2. The developing device according to claim 1, wherein the developer injection gap on the downstream side is widened. (4) The developing device according to any one of claims 1 to 3, wherein the first conveyance means also serves to convey and mix the replenishment toner.