JPH0799444B2 - Development device - Google Patents

Description

The present invention relates to a developing device used in an electrophotographic copying process or the like.

(Prior Art and Problems Thereof) Conventionally, various forms of the developing device have been provided, and a two-component developer including a magnetic carrier and an insulating toner is provided along the peripheral surface of the developing sleeve. Generally, it is transported. In this type of developing device, a magnetic roller in which the N pole and the S pole are sequentially magnetized in the circumferential direction on the outer peripheral portion is built into the developing sleeve, and the magnetic force of the magnetic roller causes the developer to be brush-shaped around the developing sleeve. While being attracted to the surface, the brush-shaped developer is conveyed in one direction while being agitated by the movement of the magnetic field due to the rotation of the magnetic roller.

However, in order to convey the developer based on the rotation of the magnetic roller, it is necessary to rotate the magnetic roller at a considerably high speed, which increases the load on the drive system of the developing device,
This goes against the recent trend toward smaller, lighter and more compact copying machines.

Therefore, by fixing the magnetic roller and attaching the toner supply roller to the toner storage tank attached to the side of the developing sleeve, the toner in the toner storage tank is directly supplied to the peripheral surface of the developing sleeve by the toner supply roller. A portable electrostatic latent image developing device that adjusts a magnetic developer by mixing a magnetic carrier and an insulating toner on a peripheral surface of a developing sleeve and develops an electrostatic latent image using the developer is provided. It is provided.

However, in this method, the distance from the toner supply section to the developing area is small, and during that time, the insulating toner is efficiently mixed and stirred with the magnetic carrier to improve the charge level until suitable for development. The problem was how to do it.

(Means for Solving Problems) The present invention has been made to solve the above problems,
A magnet with a plurality of magnetic poles formed in the circumferential direction is fixed in the developing sleeve, and only the developing sleeve is rotated to directly supply the insulating toner to the magnetic carrier held on the developing sleeve. A developing device in which the magnetic carrier and the insulating toner are mixed and agitated and conveyed, and the magnetic developer is conveyed from a toner supply portion to a developing area along a peripheral surface thereof based on rotation of the developing sleeve. Is provided with a spike height regulating member that forms a developer pool portion on the peripheral surface of the developing sleeve upstream of the developing area in the developer transport direction, and a developer stirring roller is provided in the developer pool portion. In addition to the above, a developer receiving plate is provided between the developer stirring roller and the developing sleeve.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, (1) shows a photosensitive drum, (2) shows a developing device according to the present invention, the photosensitive drum (1) has an outer diameter of 80 mm, a rotation speed of 43 rpm, a peripheral speed of 18 cm / sec. Can be rotationally driven in the direction of arrow (a).

The developing device (2) is made of conductive non-magnetic material and has an outer diameter of 24.5 mm.
The cylindrical developing sleeve (5) is rotated at 200 rpm and the peripheral speed is 25.6.
The developing roller (5) is rotatably driven, and the developing roller (5) is housed in the developing sleeve (5) coaxially with a magnetic roller (6) having an N pole and an S pole sequentially magnetized. It is installed in the opening (3a) of the tank (3) so as to be close to the surface of the photoconductor drum (1) and has a toner storage tank (4) in the back, which is composed of an insulating toner magnetic carrier. The developer is in the direction of rotation of the developing sleeve (5) (arrow (b)).
The rotation speed is the same as the rotation speed.

The insulating toner may be magnetic or non-magnetic.

Further, in the developing tank (3), toward the center of the developing sleeve (5), a first spike height regulating plate (7) which is close to the developing sleeve (5) with a gap of 0.2 to 0.3 mm, and a second
The height control plate (8) is sequentially attached in the rotational direction of the developing sleeve (5) between the toner supply section (B) and the developing area (A), and these first height control plate (7) and Second
Space part (10) with developer height control plate (8) (developer reservoir part)
In this space (10), a developer stirring roller (9) having an outer diameter of 18 mm is provided so as to be rotatable in the direction of arrow (c) at a rotation speed of 350 rpm and a peripheral speed of 33 cm / sec.

The first spike height regulating plate (7) and the second spike height regulating plate (8)
Are both made of a non-magnetic material, and the first spike height regulating plate (7) is provided with a slit-shaped opening (7a) that uniformly extends in the axial direction of the developing sleeve (5) and through which the developer can pass. And
A developer receiving plate (7b) located between the developing sleeve (5) and the developer stirring roller (9) is provided at the tip portion thereof, and is subjected to stirring action by the developer stirring roller (9). The developer and the developer whose density is varied by being intermittently conveyed to the space (10) when passing through the opening (7a) of the first spike height regulating plate (7) are directly developed in the developing sleeve (5). ) To prevent noise from appearing in the image.

It should be noted that if the receiving plate (7b) is short, uneven stirring by the developer stirring roller (9) appears, and if it is too long, the developer accumulates on the tip portion thereof. The distance from the closest position to the tip is
It is set to 3mm. Further, the distance between the developing sleeve (5) and the developer stirring roller (9) is 0.5 to 1.0 mm, and the distance between the developer receiving plate (7b) and the tip of the second spike height regulating plate (8) is 3 to. It is set to 4 mm.

Further, the first sleeve height regulating plate (7) has the developing sleeve (5) at a position where the magnetic attraction force of the developer by the magnetic poles provided on the magnetic roller (6) is the smallest, that is, at the approximate center between two adjacent magnetic poles. Close to the surroundings.

As shown in detail in FIG. 2, the developer stirring roller (9) has an elliptical plate attached to the support shaft (91) at a predetermined angle and in a circular shape when viewed from the axial direction. (92) are formed, and these blades (92) are connected by a scooping plate (93). The scooping plate (93) further mixes the developer, and the developer supply timing is random. Therefore, the stripe pattern is not generated in the image. .

On the other hand, the side opening (4a) in the toner storage tank (4) has an outer diameter
20mm toner supply roller (12) rotation speed 200rpm, peripheral speed 2
It is rotatably driven at 0.9 cm / sec, and the toner supply roller (12) is close to the peripheral surface of the developing sleeve (5).
Moreover, the arrow (d) is synchronized with the rotation of the developing sleeve (5).
It is installed so that it can be driven to rotate in any direction. The toner supply roller (12) is made of a conductive non-magnetic material such as aluminum, and has a minute recess of about 50 μm formed on its surface by blasting or knurling.

Further, a blade (13) and a seal member (14) made of a non-magnetic material are attached above and below the opening (4a) of the toner containing layer (4), and the blade (13) is a toner supply roller. The seal member (14) is provided in contact with (12) in the direction of rotation thereof and in contact with the direction of rotation of the toner supply roller (12).

(11) is mylar, and this mylar (11) is developing device (2)
The toner is prevented from leaking out from the gap between the photosensitive drum (1) and the photoconductor drum (1) to contaminate peripheral devices.

The operation of the developing device having the above structure will be described below.

First, a starter (about 40 to 80 g) composed of a magnetic carrier and an insulating toner is stored in the space (10), and the insulating toner is loaded in the toner storage tank (4).

Then, in this state, development by the developing device (2) becomes possible. At this time, only the magnetic carrier may be loaded in the space (10) instead of the starter.

Here, the toner contained in the toner containing layer (4) enters a minute concave portion on the peripheral surface of the toner supply roller (12), and the toner supply roller (12) rotates in the direction of arrow (d). The toner is conveyed in the same direction based on the above, and the excess adhered toner is scraped off by the blade (13) to reach a portion (toner supply portion (B)) facing the developing sleeve (5) and to the developing sleeve (5). Supply a fixed amount of toner.

Note that, due to the rotation of the toner supply roller (12), the seal member (13) is brought into sliding contact with the toner supply roller (12), so that the toner in the minute concave portion of the toner supply roller (12) is frictionally charged. It

The toner supplied to the developing sleeve (5) together with the carrier held on the peripheral surface of the developing sleeve (5)
Based on the rotation, it is conveyed in the direction of the arrow (b), most of the developer is blocked by the first spike height regulating plate (7),
It is pushed by the magnetic developer that is conveyed afterwards and warps up along the first spike height regulating plate (7). Then, it passes through the slit-shaped opening (7a) and reaches the space portion (10) on the downstream side. The remaining developer is the first height control plate (7) and the developing sleeve (5).
It is transported to the space (10) on the downstream side through the gap between

Next, the developer conveyed through the slit-shaped opening (7a) to the space (10) is moved by the blade (92) based on the rotation of the developer stirring roller (9) in the direction of the arrow (c). The toner is conveyed forward on the receiving plate (7b) while being stirred, and is scooped up by the scooping plate (93), and the dropping operation is frequently performed to improve the charge level of the toner and pulverize the aggregated toner. .

At this time, since the peripheral speed of the developer stirring roller (9) is set to be higher than that of the developing sleeve (5),
The developer is conveyed to the downstream side by the developer stirring roller (9) without staying in the downstream side portion of the first spike height regulating plate (7).

The developer thus well mixed and stirred together with the developer conveyed through the gap between the first spike height regulating plate (7) and the developing sleeve (5) together with the second spike height regulating plate ( 8) and the developing sleeve (5) through the gap,
The height of the head is regulated to form a magnetic brush.

Then, this magnetic brush is formed by an exposure process (not shown) by rubbing the surface of the photoconductor drum (1) at the facing portion (developing area (A)) between the developing sleeve (5) and the photoconductor drum (1). The electrostatic latent image on the exposed surface is developed and visualized.

Further, the developer remaining on the peripheral surface of the developing sleeve (5) after passing through the developing area (A) reaches the toner supply roller (12) and the facing portion (toner supply portion (B)), where it is newly added. After the toner is supplied, it is mixed and stirred again for development.

The toner concentration in the magnetic developer on the developing sleeve (5) is electrostatically maintained at a constant value based on the potential difference between the developing sleeve (5) and the toner supply roller (12).

The potential difference is determined by the correlation between the bias voltage (16) applied to the toner supply roller (12) and the developing bias voltage (15) applied to the developing sleeve (5).

In the above embodiment, the developer receiving plate (7b) is formed at the tip of the first spike height regulating plate (7), but depending on the mounting position of the developer stirring roller (9), the first spike height regulating plate (7) may be formed. (7) is not always necessary, and in this case, the developer receiving plate (7b) may be attached to the side wall of the developing tank (3) as a bridge.

(Effects of the Invention) As is apparent from the above description, the developing device according to the present invention directly supplies the insulating toner to the magnetic carrier held on the developing sleeve, and causes the magnetic carrier to adhere to the magnetic carrier on the developing sleeve. A developing device in which an insulating toner is mixed and agitated and conveyed, and a part of the magnetic developer conveyed along the peripheral surface of the toner is supplied from a toner supply section to a developing area based on rotation of the developing sleeve. A cap height regulating member that forms a developer pool portion is provided on the peripheral surface of the developing sleeve that is blocked and upstream of the developing area in the developer transport direction, and a developer stirring roller is rotatably driven in the developer pool. At the same time, a developer receiving plate is provided between the developer stirring roller and the current sleeve.

Therefore, in the developer pool, the developer is conveyed, scooped, and dropped by the developer stirring roller to be sufficiently mixed and stirred, and the developer is charged until it is suitable for development in a short time from the toner supply portion to the development area. You can improve your rank.

Even if the density of the developer in the developer pool varies, the density variation of the developer does not directly appear as the density variation of the developer on the developing sleeve.
A noise-free uniform density image is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a developing device according to the present invention, and FIG. 2 is a perspective view of a developer stirring roller. 5 ... Development sleeve, 6 ... Magnetic roller, 7 ... First spike height regulating plate, 7a ... Opening, 7b ... Developer receiving plate, 8 ... Second spike height regulating plate, 9 ... Developer stirring roller , 10 ... space, 12 ... toner supply roller, A ... development area, B ... toner supply section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Eto, 2-30 Azuchi-cho, Higashi-ku, Osaka City, Osaka Prefecture Minamita Camera Co., Ltd. (56) Reference JP-A-59-58455 (JP, A) JP 54-88130 (JP, A)

Claims (1)

[Claims] 1. A magnet having a developing sleeve and a magnet which is provided inside the developing sleeve and forms a plurality of magnetic poles in the circumferential direction of the developing sleeve, and which is magnetically attracted to the peripheral surface of the developing sleeve. By supplying the insulating toner to the carrier, a magnetic developer made of a mixture of the magnetic carrier and the insulating toner is adjusted on the peripheral surface of the developing sleeve, and an electrostatic latent image is formed using this magnetic developer. A developing device for developing, in which part of the magnetic developer that is conveyed from the toner supply section to the developing area along the peripheral surface of the developing sleeve is blocked by rotation of the developing sleeve, and the developing area is developed. A spike height regulating member that forms a developer pool portion is provided on the peripheral surface of the developing sleeve on the upstream side in the developer transport direction, and a developer stirring roller is provided in the developer pool portion and the developer stirring roller A developing device, wherein a developer receiving plate is provided between the developing sleeve and the developing sleeve.