JPS63199384A - Electrostatic latent image developing device - Google Patents

Abstract

PURPOSE:To remove the uneven density of toner in the succeeding toner feeding area, to supply a developer kept at always constant density and to obtain an uniform image by feeding a developer obtained by mixing toner in a developer stagnated part with a carrier to the surface of a developing sleeve. CONSTITUTION:Toner in a hopper 50 is carried to toner feeding roller 53 in accordance with the rotation of blades 56, 57 and entered into fine recessed parts on the surface of the roll 53. A magnetic brush 53 frequency contacts toner by an oscillating electric field in a feeding area Y of the roller 53 and the toner is efficiently supplied to the surface of the developing sleeve 43. The greater part of the developer passed through a developing area X of the sleeve 43 is scraped from the surface of the sleeve 43 at an opposite part to an napping regulating member 45 and mixed with the developer in the stagnated part 46 and the mixed developer is passed through the opposite part to the member 45 and carried to the area Y. Thereby, the toner is fed in the area Y, and at the time of passing the area Y, a uniform developer layer can be formed on the surface of the sleeve 43.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing device used in an image forming apparatus such as a copying machine.

(Prior Art and its Problems) Conventionally, the electrostatic latent image developing device is equipped with a developing sleeve incorporating a plurality of magnets and a toner supply roller having minute recesses formed on its surface. The toner is supplied from the toner supply roller to the carrier magnetically held on the circumferential surface of the developing sleeve, and the carrier and toner are mixed and stirred on the surface of the developing sleeve to charge them with different polarities. It has been proposed to prepare a component developer, bring this developer into contact with an electrostatic latent image on an electrostatic latent image carrier, and electrostatically supply charged toner to the electrostatic latent image.

Therefore, in this type of developing device, the toner supplied to the developing sleeve at the opposing area between the developing sleeve and the toner supply roller (hereinafter referred to as the "supply area") is transferred to the opposing area between the developing sleeve and the electrostatic latent image carrier. (hereinafter referred to as the "development area"), it is necessary to bring the carrier into sufficient frictional contact with the carrier to increase the amount of charge until it is suitable for development.

Therefore, generally between the supply area and the development area,
A height regulating member is provided facing the outer peripheral surface of the developing sleeve,
Is the developer conveyed on the circumferential surface of the developing sleeve enough on the nq side of the brush height regulating member? I try to mix and stir this.

However, once the developer is cut into ears on the front side of the spike height regulating member, it is pushed by the developer conveyed from behind and rotates, and comes into contact with the developer on the developing sleeve discontinuously. The surface of the sleeve? This has the problem that a stirring pattern of the developer is formed, which directly appears as density unevenness in the image.

In addition, in order to stably obtain images with a constant density, it is necessary to replenish the surface of the developing sleeve with an amount of toner that is commensurate with the amount consumed in the developing area. Generally, when a large number of copies are to be made, the amount of toner consumed is large, so the amount of toner to be replenished is also large.

However, if we attempt to completely replenish the toner supply area by enlarging the shape of the minute concave portions on the surface of the toner supply roller for this purpose, toner will be oversupplied when developing normal character images, and uncharged toner will become powder. This causes problems such as smoke forming and adhering to the surface of the static N latent image carrier, causing fog to appear on the image and contaminating the inside of the machine.

(Means for solving the problems) The present invention has been made to solve the problems mentioned above.
In the electrostatic latent image developing device, a brush height regulating member facing the electrostatic latent image carrier is provided in a region where the developer passing through the portion facing the electrostatic latent image carrier reaches a portion facing the toner supply roller. A member is provided, and a developer reservoir is formed on the second liquid side in the developer transport direction.

(Example) Hereinafter, the present invention will be described with reference to the accompanying drawings showing one example.

Is Figure 1 the invention? A schematic cross-section of a copying machine equipped with such a developing device will be shown, and its configuration will be explained along with its copying operation.

First, the print switch (not shown) is turned on and -3
= When the photosensitive drum (3I) located approximately at the center of the main body (+) is rotating in the direction of the arrow (a), the surface of the photosensitive drum (31) is is uniformly charged.

Next, the document platen glass (2
) scans in the direction of the arrow (X), while the optical system (
The reflected light of the light irradiated onto the document from the exposure lamp (61) of 6) is reflected by a mirror and a Selfox lens array (6).
2), the surface of the photoreceptor drum (31), which is charged as described above, is exposed to light, and an electrostatic latent image corresponding to the original image is formed on the surface of the photoreceptor drum (31).

This electrostatic latent image is developed at a portion facing a subsequent developing device (33), and a toner image corresponding to the original image is formed.

On the other hand, copy paper (S) is fed from a paper feed section (not shown) and is moved by a pair of transport rollers (71) and (72) at a timing [l].
- The photosensitive drum (3I) and the transfer charger (73) are transported to the front side of the toner image 1iij according to the timing [l-ra pair (73)].
4), and the toner image is transferred to the copy paper by discharge of the transfer charger (74).

This copy paper (S) is transferred to the photoreceptor drum (3) by an appropriate means.
1), the toner is conveyed between a pair of fixing rollers (76) by a conveyor belt (75), where the toner is melted and fixed onto the copy paper, and then transferred to a paper discharge section (not shown). is discharged.

On the other hand, the surface of the photoreceptor drum (31) to which the toner image has been transferred is exposed to the blade (35) of the subsequent cleaning device (34).
), the remaining toner is scraped off, and the remaining toner is further irradiated with light from the exposure lamp (6I) again to erase the residual charge and prepare for the next development. Note that the toner drawn by the blade (35) is collected by a collection roller (36).

Next, regarding the developing bag fW (33) according to the present invention, the second
This will be explained with reference to the figures.

Note that the developing device (33) is a photosensitive drum (31).

An image forming unit (3) is configured together with an electrostatic charger (32) and a cleaning device (34), and the image forming unit (
3) is detachably attached to the copying machine main body (1), and a bias (Vp) is applied to the photosensitive drum (3I).

The developing device (33) roughly consists of a developing section (40) and a toner hopper (50). It can be replaced with the hopper as appropriate.

The developing section (40) has a developing sleeve (43) rotatable in the direction of arrow (b) within a space formed by an upper frame (4I), a lower frame (42), and a side frame (not shown), and It is accommodated so as to face the photosensitive drum (31) with a predetermined developing section gap (0.7 mm) therebetween.

The developing sleeve (/+3) incorporates a magnetic roller (44) in a fixed shape, and the magnetic roller (44) has a plurality of magnets with magnetic poles extending in the axial direction. S and N are installed alternately on the outer periphery.

Further, the developing sleeve (43) has a developing bias (Vb).
is applied.

A brush height regulating member (45) is attached to the lower frame (42), the tip of which is attached to a predetermined brush height regulating gear knob (0.4 m
The developing sleeve rotation direction of the brush height regulating member (45) is located at the developer reservoir (4
6) is formed.

A toner supply roller (51) is rotatably mounted in the front opening (52) of the toner hopper (50) in the direction of arrow (C).
In addition, the developing sleeve (43) and a predetermined supply gear knob (
They are arranged so as to face each other with a distance of 0.6 mm).
Blades (54) made of non-magnetic material attached to the upper and lower parts of the opening (52), and toner spill prevention members (55)
are in pressure contact with the circumferential surface of the toner supply roller (51), and the opening (52) is closed.

The toner supply roller (53) has minute irregularities formed on its outer circumferential surface by blasting, J etching, etc.
A recovery bias (V s) superimposed with ns) is applied.

Behind the toner supply roller (53), two conveyor blades (56) and (57) are arranged in parallel and in the same direction (arrow (
d) and (e) direction).

By the way, toner is stored inside the toner hopper (50), and a two-component developer consisting of carrier mixed with toner at a ratio of 8 wt% is on the outer peripheral surface of the developing sleeve (43) and the developer reservoir (46). Retained.

Furthermore, when the toner and carrier come into frictional contact with each other, the toner is positively charged and the carrier is negatively charged.

Next, the operation of the developing device (33) having the following configuration will be explained.

First, when the continuous copying operation starts, the developing sleeve (4, 3), the toner supply roller (53), the conveying blade (
56) and (57) are arrows (b) and (C), respectively.
, (d).

Rotate in direction (e).

The toner in the toner hopper (50) is conveyed toward the toner supply roller (53) based on the rotation of the conveyance blades (56) and (57).
) is incorporated into the microscopic depressions on the surface.

The toner held on the surface of the toner supply roller (53) is conveyed in the direction of arrow (C) based on its rotation, and the excess toner is scraped off by the pressure contact part of the regulation blade (54), and the blade ( 54), and is transported to the supply area (Y) in the form of a one- or two-layer thin film.

On the other hand, on the outer peripheral surface of the developing sleeve (43), the developer is held in a magnetic brush state along the lines of magnetic force generated from the magnet of the magnetic roller (44).
3) and the toner supply roller (53) face each other, the toner conveyed on the toner supply roller (53) by the magnetic brush (53) is scraped off.

Note that since a bias (Vs) in which alternating current (V rms) is superimposed on direct current (Vss) is applied to the toner supply roller (53), an oscillating electric field is generated in the supply area (Y).
This causes the toner and developer to vibrate, so that the magnetic brush and the toner frequently come into contact with each other, and the toner is efficiently supplied to the surface of the developing sleeve (43).

The toner taken into the magnetic brush is transferred to the developing sleeve (4).
3) When being conveyed in the direction of arrow (b) according to the rotation,
It comes into contact with the carrier to improve its charging potential, and is electrostatically supplied to the electrostatic latent image area formed on the surface of the photoreceptor drum (3I) in the development area (X).

The developer that has passed through the development area (X) continues to move toward the arrow (+1
) direction, and most of it is scraped off from the surface of the developing sleeve (43) at the portion facing the brush height regulating member (45).

This scraped off developer is removed from the developer reservoir (46).
Some of the developer is mixed with the developer stored in the developing sleeve (44) and is attracted by the magnetic force of the magnetic roller (44).
43), and is conveyed to the supply area (Y) through a portion facing the height regulating member (45).

Note that the consumption pattern on the developing sleeve (43) in which toner is consumed in the developing area (X) and the toner density has decreased is as follows:
After the toner is mixed and stirred in the developer reservoir (46) and the toner concentration is averaged, toner is replenished in the next supply area (Y), and at the time the toner passes through the supply area (Y), the developing sleeve (43) A uniform developer layer is formed on the surface.

Note that the developing sleeve (43) is located at the developer reservoir (46).
Even if there is unevenness in the amount of toner replenished on the surface of the toner, the unevenness in replenishment will be erased by the toner supply operation in the next supply area (Y). The electrostatic latent image is uniformly supplied with toner.

In addition, even if images with many solid areas are continuously copied, the consumption pattern is such that the developer is first mixed and stirred in the developer reservoir (46), and the developer concentration in the developing sleeve (6) J: is averaged. Since the toner supply area (Y) can compensate for the shortage after the toner has been developed, the toner supply capacity of the toner supply roller (53) only needs to be sufficient to develop a normal image.

By the way, in the above embodiment, as shown in FIG. 2, after the developer passes through the development area (X), it passes through the development sleeve (
) is conveyed and rolled to the supply area (Y) along the lower surface of the developing sleeve (43), and the height regulating member (45) is opposed to the developing sleeve (43) in the area between. ) rotates in the direction opposite to the direction of arrow (b), the height regulating member (45) may be opposed to the upper surface of the developing sleeve (43).

However, if the developer reservoir (46) is formed under the developing sleeve (43) as in the above embodiment,
The weight of the developer is directly applied to the developing sleeve (43), and the height regulating member (45) and the developing sleeve (43)
There is no drawback that the developer gets clogged between the two and the rotational torque becomes large.

(Effects of the Invention) As is clear from the following explanation, in the developing device according to the present invention, the area where the developer held in the developing sleeve is conveyed from the developing area to the supply area, A height regulating member facing the developing sleeve is provided to form a developer reservoir, and here the developer sufficiently mixed with toner and gear is applied to the surface of the developing sleeve. After the ilr is filled up, the shortage is further replenished in the supply area.

Therefore, even if there is uneven density of the toner when it passes through the part facing the height regulating member, this unevenness will be erased by being replenished with toner in the next supply area, so that the developing area will always have a constant density of developer. agent is supplied, and a homogeneous image without density unevenness can be obtained.

Furthermore, even if a large number of copies are made in succession, the toner consumption pattern of the developing sleeve is first replenished with toner in the developer reservoir, and then the missing amount is replenished in the supply area. There is no need to replenish toner in the toner supply area, and the supply capacity of the toner supply roller can be maintained as normal.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a copying machine, and FIG. 2 is a sectional view of an image forming unit having a developing device according to the present invention. DESCRIPTION OF SYMBOLS 1...Main body, 2...Document table glass, 3. Image forming unit, 6.. Optical system, 3I... Photosensitive drum, 33.
- Developing device, 40... Developing section, 43... Developing sleeve, 44, Magnetic roller, 45... Brush height regulating member, 46
・Developer reservoir, 50... Toner hopper, 53...
・Toner supply roller.

Claims (1)

[Claims] (1) A developing sleeve containing a plurality of magnets, and a toner supply roller that supplies toner to a carrier magnetically attracted to the outer circumferential surface of the developing sleeve. An electrostatic latent image developing device that prepares a developer consisting of a carrier and a carrier, and uses the developer to supply toner to an electrostatic latent image formed on the surface of an electrostatic latent image carrier. A brush height regulating member facing the electrostatic latent image carrier is provided in a region where the developer passing through a portion facing the image carrier reaches a portion facing the toner supply roller;
An electrostatic latent image developing device characterized in that a developer reservoir is formed on the upstream side in the developer transport direction.