JPS62251773A - Developing device - Google Patents

Abstract

PURPOSE:To reproduce a stable high-quality picture, by fitting driven members whose diameters are slightly larger than that of a developing sleeve to the supporting shaft of the sleeve and pressure-contacting the driven members with a photosensitive drum. CONSTITUTION:Driven members provided on both sides of a developing sleeve 4 are pressure-contacted with a photosensitive drum and the interval between the drum 1 and sleeve 4 is maintained constantly and, at the same time, the developing sleeve 4 and a supplying roller 9 which supplies the sleeve with toner are supported by the same bearing member 35 and the interval between them is held constantly irrespectively whether or not the photosensitive drum 1 is mounted. Therefore, it never occurs that the developing agent and toner drop into the space between the sleeve 4 and roller 9 and is consolidated and hardened by compaction, even when the drum 1 is removed. Accordingly, the supplying and recovering efficiencies are made constant and a stable high-quality picture can be reproduced.

Description

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

(Prior Art) In recent years, as one aspect of the above-mentioned developing device, a photoreceptor drum and a facing staggered developing sleeve are provided inside the developing tank, and a toner supply roller facing this is provided, and an insulating layer is provided from the toner supply roller to the surface of the developing sleeve. The magnetic toner is supplied, and the toner and magnetic carrier are mixed together on the developing sleeve.
It has been proposed to develop an electrostatic latent image on the surface of a photoreceptor drum using a magnetic brush formed by a magnet built into a developing sleeve.

In this type of developing device, the distance between the developing sleeve and the photoreceptor drum (developing gap) must be set strictly. Driven rollers having a radius as large as the developing gap are attached to both sides, and are pressed against both sides of the photoreceptor drum to maintain the developing gap constant.

For this reason, the developing sleeve is independently movable slightly toward the photoreceptor drum, and is always urged toward the photoreceptor drum.

(Problem to be Solved by the Invention) However, since the toner supply roller is installed in a fixed state, when the photoreceptor drum is taken out during cleaning or inspection of the copying machine, the developing sleeve is attached to the mounting part of the photoreceptor drum. the distance between the developing sleeve and the toner supply roller (
t' (feed gap) is widened, and the toner falls during this time.

When the photoreceptor drum is returned to its original state, the developing sleeve moves toward the toner supply roller and the developing gap returns to its normal developing state, but at this time, the toner that has fallen into the widened supply gap is removed. Consolidated and solidified.

Therefore, when the coagulated and solidified toner adheres to the developing sleeve, it is conveyed as the developing sleeve rotates, and the height regulating plate that is installed opposite the developing sleeve and adjusts the amount of developer conveyed to the developing area. Caught between
There is a problem in that it obstructs the normal flow of developer and causes poor conveyance.

Additionally, if the coagulated and solidified toner adheres to the toner supply roller, this will cause variations in the amount of toner supplied to the developing sleeve, and as a result, the amount of developer conveyed to the developing area will change over time, resulting in defective images. There is a problem with image distortion.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems. A driven member having a diameter slightly larger than that of the developing sleeve is attached to the supporting shaft of the developing sleeve, and the driven member is pressed against the photoreceptor drum so that not only the developing gap but also the supply gap are kept constant at all times. .

(Example) DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings which are one embodiment of the present invention.

FIG. 1 shows a developing section of an electrophotographic copying machine according to the present invention.

The developing device (2) is arranged on the side of the photoreceptor drum (1), and supplies toner to the electrostatic latent image formed on the photoreceptor drum (1). 3
A developing sleeve (4) adjacent to the photoreceptor drum (1) is provided in the developing tank (3) consisting of a) and a cover (3b), and a toner storage tank (4) is provided on the back side of the developing sleeve (4). 16), and the toner in the toner storage tank (16) is supplied to the surface of the developing sleeve (4) by a toner supply roller (9).

The developing sleeve (4) is a cylindrical body made of a conductive non-magnetic material such as aluminum, to which a developing bias voltage is applied, and is rotated counterclockwise [in the direction of arrow (b)] by a driving means (IOQ) described below. It can be rotated.

Inside the developing sleeve (4), there is a magnetic roller (20) equipped with a plurality of magnets with S and N poles alternately magnetized on the outer periphery.
are housed coaxially in a fixed state, and the magnetic developer made of a mixture of insulating toner and magnetic carrier is rotated at the same speed as the rotational speed of the developing sleeve (4) [in the direction of arrow (b)]. It is intended to be transported by

The main developer stirring plate (5) has a cover (3) made of a non-magnetic material.
b) is fixedly installed on the side of the photosensitive drum (1), and its tip is installed close to the upper circumferential surface of the developing sleeve (4), and a height regulating plate (5a) is provided on the upstream side of the close portion. There is.

The height regulating plate (5a) is movable toward the developing sleeve (4), and has small protrusions (not shown) formed at both ends thereof, and a temporary spring (5b) provided at the upper part of the main developer stirring plate (5). ), the small protrusion comes into pressure contact with the developing sleeve (4), and the gap between the height regulating plate (5a) and the developing sleeve (4) is maintained constant.

The main developer stirring plate (5) having the above-mentioned configuration moves a part of the magnetic developer conveyed in the direction of arrow (b) on the circumferential surface of the developing sleeve (4) to a base on the upstream side of the developing area (A). This is used to adjust the amount of developer conveyed to the development area (A), and the auxiliary developer stirring 1 (7) provided on the upstream side adjusts the amount of developer conveyed to the development area (A).
8).

The auxiliary developer stirring plate (7) is made of a non-magnetic conductive material like the main developer stirring plate (5), and is attached to a supporting member (6) fixed to the cover (3b). axial direction and
It is attached movably toward the center of the developing sleeve (4), and includes a toner supply roller (9) and a blade (11).
) and the powder smoke prevention film (14) form a vacant chamber (14).

The width in which the developing sleeve (4) can reciprocate in the axial direction is B (see Fig. 3), and in this embodiment,
It is set to 3mm.

Further, the auxiliary developer agitation f (7) is controlled by a spring (72) attached to the support member (6).
) is energized towards hl? Small protrusions (not shown) provided on the part of the auxiliary developer stirring plate (7) facing the developing sleeve (4) are pressed against both sides of the developing sleeve (4), and the auxiliary developer stirring plate (7) and the developing sleeve (4) are pressed against each other. ) is kept constant.

Furthermore, as shown in FIG. 2, the auxiliary developer stirring plate (7) is formed with a plurality of slit-shaped openings (71) through which the developing agent extends in the axial direction of the developing sleeve (4). There is.

The toner supply roller (9) is made of a conductive non-magnetic material, such as aluminum, and its surface has minute irregularities of about 50 μm formed by blasting. This toner supply roller (9) is arranged close to the back side of the developing sleeve (4), and a recovery bias voltage is applied to the developing sleeve (4) by a drive element/stage (10(1)). 4) and can be rotated in the direction of arrow (c).

1-ner supply [! - Partition wall (10) on one side of La (9)
The spring (12) has one end attached to the upper rear end of the casing (3a), and the spring (12) has one end attached to the upper rear end of the casing (3a).
The end of the blade (11) provided at the bottom of the partition wall (10) is constantly biased in the direction of arrow (d) to supply toner.
9) in the direction of rotation thereof.

A casing (3a) is located below the toner supply roller (9).
) is attached to a sole member (15), and this sole member (15) is in pressure contact with the toner supply roller (9) along the direction of rotation thereof.

The i-toner storage tank (I6) includes a partition wall (10), a blade (11), a toner supply roller (9), and a sole member (
15) is formed by partitioning the rear part of the phenomenon tank (3). Inside this toner storage tank (16), there is a stirring blade (17).
) is installed to be movable in the direction of arrow (e) by the following driving means (+00), and the toner storage tank (16)
Mixed with insulating toner contained within.

I try to stir it.

In addition, the casing (3a), the main developer stirring Ifi, (5
) are fitted with spill prevention 1ff (18) and dust smoke prevention Mylar (19) on the opposite sides of the photoconductor drum (1) to prevent developer and toner from scattering from the developer tank (3). I try to do that.

The driving means (IOQ) of the developing device will be explained below with reference to FIG.

In FIG. 3, (III) is a wheel fixed to the end of the support shaft (4a) of the developing sleeve (4), and this wheel (I
A drive belt (llO) is hung on the wheel (ll) so as to transmit the rotational force of a drive source (not shown) to the wheel (ill).

Driven rollers (+20) are rotatably attached to both sides of the support shaft (4a), and the radius of this driven roller (7 (+20)) is larger than that of the developing sleeve (4).
Ds) to maintain a constant distance between the photosensitive drum (1) and the developing sleeve (4). Also, the support shaft (4a) is equipped with gears (+01) (102
) is fixedly installed, and the gear (1,01) is connected to the photoreceptor drum (
A gear (+03) fixedly attached to the spindle of the toner supply roller (9) and a gear (+03) rotatably attached to the spindle (9a) of the toner supply roller (9).
It meshes with [)4). Another gear (+02)
is meshed with a gear (105) provided on the support shaft (9a) of the toner supply roller (9) through a gear (not shown), and the rotational force of the drive belt (110) is applied to these gears (102), ( 105) to the toner supply roller (
9).

Further, a support shaft (3a) is fixed to the side of the developer tank (3), and the support shaft (3a) has the support shaft (3a) fixed to the side of the developer tank (3).
A gear (106) equipped with a cam (106a) formed diagonally with respect to a) is rotatably attached to the gear (i).
t) 6) is the support shaft (9) of the toner supply roller (9) marked Ω7j.
A gear (+04) rotatably attached to a) and a gear (108) fixedly attached to the support shaft (17a) of the stirring blade (17)
It meshes with.

Further, a truncated conical contact portion (74) is attached to the first end of the support shaft (73) of the hli auxiliary developer stirring plate (7), and this contact portion (74) is connected to the supporting shaft (73). It is biased in the direction of arrow (P) by a spring (75) provided between the tank (3) and is in pressure contact with the cam (106a) of the gear (106). As a result, when the gear (106) rotates, the contact portion (74) slides on the cam (106a), and the auxiliary developer stirring plate (7) moves in the direction of the arrows (P) and (P'). (
Perform the periodic motion of B).

An insertion portion (31) having an oval-shaped recess (32) shown in FIG. 4 on the outside is formed on both side walls of the developer tank (3). is the photosensitive drum (1)
It is aimed at An oval-shaped bearing member (35) whose length in the longitudinal direction is slightly smaller than the recess (32) is fitted into the recess (32), and supports the support shaft (4a) of the developing sleeve (4). The support shaft (9a) of the toner supply roller (9) is rotatably supported by a bearing member (35) via bearings (36) and (37), respectively. The bearing member (35) is made of an insulating resin and insulates the bias voltages applied to the developing sleeve (4) and the toner supply roller (9).

Further, a spring (34) is attached to a housing portion (33) formed at the rear of the recess (32), and this spring (34) causes the bearing member (35) to move toward the photoreceptor drum (33).
1) [in the direction of arrow (g)], and the driven rollers (+20) are in pressure contact with both sides of the photoreceptor 1; ram (1).

The operation of the developing device (2) having the above configuration will be explained.

First, a magnetic carrier and an insulating film are placed in the empty chamber (14) above the toner supply roller (9) shown in FIG. - A starter made of a mixture with toner is loaded, and insulating toner is loaded into the toner storage tank (16). At this time, only a magnetic carrier may be loaded into the empty chamber (14) instead of the starter. Then, with the insulating toner loaded, the electrostatic latent image can be developed by the developing device (2).

In this state, the drive belt (110) connected to the drive source shown in FIG.
operates, and the wheel (111) and developing sleeve (4)
The supporting shaft (4a) rotates in the direction of arrow (b).

As a result, the photoreceptor drum (1) rotates in the direction of arrow (a) via the gears (101) and (103), and as the driven roller (120) rotates as a result of the photoreceptor drum (1), the gear (1G2) and (105), the toner supply roller (9) rotates in the direction of arrow (c). At the same time, the gear (106) via the gears (101) and (104) rotates in the direction of the arrow (f), and the stirring blade (17) rotates in the direction of the arrow (e) via the gear (108).

At this time, the contact portion (74) of the auxiliary developer stirring plate (7) moves a width (B) in the directions of arrows (P) and (P') by periodically changing the pressure contact position with the cam (106a). ) to vibrate. In addition, the height regulating plate (5a) and the auxiliary developer stirring plate (7) each have a small protrusion provided on the part facing the developing sleeve (4), which is connected to the plate spring (5b) and the spring (7).
2), and the gap with the developing sleeve (4) is kept constant.

By operating the developing device (2) as described above,
The toner stored in the toner storage 1ff (1G) is
The toner supply roller (9) enters the four minute parts on the circumferential surface and is conveyed in the same direction based on the rotation in the direction of the arrow (C). It is preliminarily charged by the friction, reaches the portion (13) facing the developing sleeve (4), and is scraped off by the magnetic brush on the developing sleeve (4). Alternatively, the toner is electrostatically attracted to the carrier on the developing sleeve (4), thereby being supplied from the toner supply roller (9) onto the developing sleeve (4). On the other hand, the developing sleeve (
4) and the toner supply roller (9), the toner on the developing sleeve (4) is electrostatically collected, and the toner concentration in the magnetic developer is maintained constant.

As a result, the developer containing toner is retained on the developing sleeve (4) to the extent that an appropriate image density can be maintained.

The toner supplied to the developing sleeve (4) is transferred to the carrier held on the circumferential surface of the developing sleeve (4).
Based on the rotation, the developer is conveyed in the direction of arrow (b), most of the developer is blocked by the auxiliary developer stirring plate (7), and the auxiliary developer is pushed by the magnetic developer conveyed later. It curves up along the stirring plate (7) and the opening (71)
and is sent to the vacant room (8) on the downstream side. The remaining developer passes through the gap between the auxiliary developer stirring plate (7) and the developing sleeve (4) and reaches the empty chamber (8) on the downstream side. Vacancy(
8) Most of the developer conveyed to the height regulating plate (5a)
, and blocked by a main developer stirring plate (7),
Mix and stir by rotating clockwise in the empty chamber (8) along this direction.

At the same time, based on the reciprocating motion of the auxiliary developer stirring plate (7) in the directions of arrows (P) and (P゛), the developer passing through the opening (71) of the auxiliary developer stirring plate (7) is moved in the lateral direction [ The force in the directions of arrows (P) and (P') shown in FIG. 3 is applied, the mixture is stirred in that direction, and the developer and toner are made uniform in the lateral direction.

In this way, some of the developer that is evenly mixed and stirred in the transport direction [arrow (b) direction] and in the horizontal direction (arrow (P) and (P') directions) Board (5a
) and the developing sleeve (4), the brush height is regulated to form a magnetic brush, and the magnetic brush is connected to the developing area (A).
The surface of the photoreceptor drum (1) is rubbed, and the electrostatic latent image on the surface is developed and visualized.

After being subjected to the development, the magnetic developer remaining on the circumferential surface of the development sleeve (4) reaches the part (r3) facing the toner supply [1-ra (9)], and is transferred to the developing sleeve (1). Here, new toner is supplied, and when it reaches the empty chamber (8) again, the surface is uniformly replenished with developer mixed and stirred with a iron. Therefore, the toner consumption pattern consumed in the previous development is replenished with sufficiently mixed and stirred developer to erase the previous history. Therefore, it is possible to obtain a copied image free from density unevenness and noise.

Next, when the photosensitive drum (1) is removed from the state shown in FIG. The bearing member (35) comes into contact with the photosensitive drum (1) side of the recess (32) and is regulated in position.

At this time, the developing sleeve (4) and toner supply roller (9)
) are each held at a constant distance between their axes by the bearing member (35), so the developer and toner located above will not fall into these gaps.

When the photoreceptor tram (1) is installed in its original state, the driven rollers (1, 20) are pushed by the photoreceptor drum (1) and return to the state shown in FIG. 3 against the spring (34).

In the embodiment, the bearing member (35) is attached to the photoreceptor drum (1).
), but the invention is not limited to this. That is, as shown in FIG. 5, the recess (32') of the developer tank (3) is connected to the bearing member (
35) is shaped to be able to swing around the support shaft (9a) of the toner supply roller (9), and the driven roller (120) is moved along the circumferential surface of the photoreceptor drum (1) from the direction of the arrow (g''). It is also possible to press the l/gner supply roller (
Since the position of the toner supply roller (9) is constant, it is easy to roll the toner around the toner supply roller (9). Further, since the blade (II) does not displace, its setting is easy.

Furthermore, in the above embodiments, a two-component developer consisting of an insulating toner and a magnetic carrier was used, but the present invention is not limited to this, and a one-component developer may be used.

(Effects of the Invention) As is clear from the above description, the present invention has the following advantages: the driven members provided on both sides of the developing sleeve are brought into pressure contact with the photoreceptor drum, and the distance between the photoreceptor drum and the developing sleeve is maintained constant. Second, the phenomenon sleeve and the supply roller for supplying toner thereto are supported by the same bearing member, and the distance between them is maintained constant regardless of whether or not the photosensitive drum is attached. There is.

Therefore, after the photoreceptor drum is removed, more developer or toner than at the time of the phenomenon will not fall between the developing sleeve and the supply roller, and will not be compressed and coagulated and solidified.

In addition, there is no need to adjust the distance between the developing sleeve and the supply roller, making assembly simple and easy, and improving positional accuracy.

Therefore, the toner supply/collection efficiency is constant,
It is possible to reproduce stable, high-quality images.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a developing device according to the present invention, FIG. 2 is a perspective view of an auxiliary developer stirring plate, and FIG. 3 is a partial sectional view of the developing device showing the driving means and bearing structure of the developing device. FIG. 4 is a side view showing the developing sleeve and the bearing member of the toner supply roller, and FIG. 5 is a side view showing another embodiment. l...Photosensitive drum, 2...Developing device, 3...
...Developer tank, 4...Developer sleeve, 4a
... Support shaft, 5 ... Main developer stirring plate, 5
a... Height regulation plate, 7... Auxiliary developer stirring plate, 9... Toner supply roller, 35... Bearing member,
+00...driving means, 12G...driven roller.

Claims (1)

[Claims] (1) A developing device that supplies developer to the surface of the developing sleeve from a supply roller facing the developing sleeve, conveys the developer to a portion facing the photoreceptor drum, and develops the electrostatic latent image on the surface of the photoreceptor drum. The developing sleeve and the toner supply roller are pivotally supported by the same bearing member, and a driven member having a slightly larger diameter than the developing sleeve is attached to the supporting shaft of the developing sleeve, and the driven member is connected to the photosensitive drum. A developing device characterized by being in pressure contact with.