JPS62145269A - Developing device - Google Patents

Abstract

PURPOSE:To form a uniform developer layer surface which has neither a projection nor a recess by holding a member which levels the surface of a developer layer so that it can contact and leave a rotating developer carrier and bringing the member into contact with the developer layer with the rotating force based upon its own weight. CONSTITUTION:The image carrier 1 and a sleeve 2 rotate as shown by arrows and an AC bias 13 which is superposed upon DC is applied to the sleeve 2. A developer 10 composed of a mixture of toner and magnetic carriers is held and conveyed on the sleeve by magnetic poles N3 and S2 and cut by a blade 6 to proper layer thickness, and the surface of the developer layer is leveled uniformly by the leveling plate 7. The leveling plate has a shaft hole 12 in the lengthwise center part and a rotating shaft 9 is run through the shaft hole 12 to hold the whole leveling plate, so the leveling plate is allowed to rotate around an axis (a) as shown by an arrow (b). Further, the leveling plate is brought into contact with the developer layer with the rotating force based upon the weight of the leveling plate around the rotating shaft 8 and when a large load is placed on the contacting part, the rotating force operates so as to lift it.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing device in a recording device such as an electrostatic recording device.

In particular, the present invention provides a technique effective for a non-contact type two-component developing device that maintains the developer carried on a developer carrier in a layered state in a non-contact manner in a developing section with respect to an image carrier.

(Prior art) This type of non-contact type two-component developing device normally performs development by applying an alternating electric field within the development gap between the sleeve and the image carrier, and the smaller the development gap, the better the development performance. Therefore, in order to make the developer layer non-contact with the image carrier, it was necessary to reduce the code thickness of the developer layer. In order to meet this requirement, the developing position corresponds to the area between the two poles of the magnet fixed in the sleeve, and the developing area is the area where the ears of the developer layer lie, making it easier to obtain the non-contact condition. The method and apparatus have recently been published in Japanese Patent Application Laid-Open No.
-91453 publication, 60-14263 publication, 60-14263 publication
It is disclosed in the publication No. 0-176069.

Such a developing method has the disadvantage that if the surface of the developer layer in the developing section has irregularities, slight unevenness in density will occur due to the irregularities. Generally, it is known to level the developer surface by using an elastic member, as disclosed in Japanese Patent Laid-Open No. 54-43038.

However, with the conventional leveling member,
As stated in Publication No. 9, in the case of a fixed type, it is difficult to use because it is difficult to make adjustments to achieve the gap accuracy between the leveling member and the sleeve, or use spacer rollers. Ta. In particular, differences in the degree of leveling of the developer layer on the sleeve in the longitudinal direction tend to occur, and preparation to eliminate this problem is troublesome. Furthermore, although such leveling was carried out by bringing the tip end of the leveling member into contact with the surface of the developer layer, some unevenness remained on the surface.

(Objective) The basic object of the present invention is to eliminate the above-mentioned drawbacks of the conventional example and form a uniform developer layer surface with no irregularities. A non-contact type two-component developing device that can increase the latitude of gap adjustment with the leveling member and provide clear, high-quality images with no "brush marks", "fogging", "density unevenness", etc. is intended to provide.

(Summary of the Invention) The present invention provides that a leveling member for leveling the surface of a developer layer can be held in the a-tangential direction with respect to a rotating developer carrier, and the leveling member can be held in the a-tangential direction with respect to the rotating developer carrier, and that the leveling member can be held in the a-tangential direction with respect to the rotating developer carrier, and that the leveling member can be held in the a-tangential direction with respect to the rotating developer carrier. A developing device, characterized in that it makes contact with a developer layer.

(Embodiment) FIGS. 1 and 2 show embodiments of the present invention, in which 1 is an image carrier, 2
3 is a developing sleeve, 3 is a magnet fixed inside the sleeve, 4.
5 is a conveying screw, 6 is a cutting blade, 7 is a leveling plate, and 8.9 is a rotating shaft.

The image carrier 1 and the sleeve 2 rotate in the direction of the arrow in the figure, and an AC bias 13 with DC superimposition is applied to the sleeve 2. A developer lO consisting of a mixture of toner and magnetic carrier is placed at magnetic pole N3. It is held and conveyed on the sleeve in S2, and cut to an appropriate layer thickness with a blade 6. Thereafter, the surface of the developer layer is leveled uniformly by a leveling plate 7.

By the way, the leveling board has a U-shaped cross section, and the second
As shown in the figure, it has a shaft hole 12 at the center in the longitudinal direction. Since this shaft hole is configured to pass through the rotating shaft 9 (see Fig. 1) and hold the entire leveling plate, the leveling plate can be rotated about the axis a as shown by the arrow. It has the freedom to move. Further, the leveling plate contacts the developer layer by a rotational force due to its own weight around the rotating shaft 8, and when a high load is applied to the contact portion, a rotational force acts in the direction of lifting it ( (This is because the position of the rotating shaft 8 is on the upstream side of the contact part).

With these, the rotation axis! A function in which the contact pressures on both sides in the longitudinal direction are always balanced with respect to point a, that is, an equalizing function is created. Therefore, since the leveling plate always levels the developer layer with uniform contact pressure in the longitudinal direction, there is no need to adjust the gap between the sleeve and the leveling plate. Furthermore, since the leveling is performed at the edge of the tip bend 14, a slight cutting is performed along with the leveling, and a very uniform layer surface with no irregularities is formed.

In this way, the developer layer, whose surface is evenly leveled without any irregularities, comes closest to the image carrier, reaches the development poles S, N, and the development area between the poles, and the alternating electric field in the development gap due to the AC bias Due to this action, high quality image development with no density unevenness is achieved.

However, according to the authors' experiments, in order to obtain a more dense and uniform developer layer, the leveling plate 0 contact position should be set at N in FIG. It is preferable to bring it into contact with the downstream side, as this will result in higher image quality.

(Experiment example) When development was performed using the above developing device under the following conditions, a clear and precise print-like, high-definition, high-definition image quality with no “fogging” or “density unevenness” was obtained. Obtained by doing.

・Image carrier electrostatic latent image potential 200 to 5oov ・Development gap 300IL ・Developer layer pressure (development position) 250L ・Development bias vp P l 300Vf
3500HzVDC200V ・Magnetic carrier Toyo Ink controlled Jin carrier particle size 3
0~50g ・Toner Styrene/acrylic suspension polymer toner, particle size 2~5L ・Development polar magnetic force 1200 Gauss (S
1 + N I), process speed 270 mm/sec, development pole angle l (Ss - Nt) = 70°, leveling plate material SUS plate (inch thickness), leveling plate contact position Nl (upstream side development pole) As explained above, the 5° downstream side corresponds to the space between the two developing magnetic poles.
In a non-contact two-component developing device, the developing position is
By providing a leveling plate with a finishing/collising function downstream of the cut blade and slightly upstream of the development position, a uniform and even developer layer can be easily formed. In addition, by using the leveling plate's own weight to abut the leveling plate, the structure can be simplified, and the edge of the leveling plate allows for uniform development without any unevenness. A drug layer is formed, and dense, high-quality image development without density unevenness can be easily achieved.

Further, FIGS. 3 and 4 show another embodiment, in which the leveling plate has an L-shaped cross section. The leveling plate does not have a bend at the tip, but since the leveling is done by bringing the edge of the tip into contact with the developer layer, the same effect as the previous example can be obtained, and uniform and uneven development can be achieved. Forms an agent layer and performs high-quality development.

(Effect) The effect of the present invention is that it achieves an extremely stable and smooth surface of the developer layer, which produces thicker results for various types of development, that is, it can provide developed images of high quality. It is something.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the developing device of the present invention, FIG. 2 is a perspective view of the leveling plate and sleeve shown in FIG. 1, FIG. 3 is a longitudinal cross-sectional view of another embodiment of the present invention, and FIG. FIG. 4 is a perspective view of the main part of FIG. 3; IO is a developer, 11 is a housing, 12 is a rotation shaft hole, 1
3 is the developing bias, and 14 is the bending of the tip of the leveling plate.

Claims (5)

[Claims] (1) A two-component developer having toner particles and magnetic particles is carried on a rotating developer carrier having a fixed magnet provided therein, and the development position is between two magnetic poles of the fixed magnet,
An electric field including alternating electric field components is applied to a developing area between the developer carrier and the image carrier, the developer layer is not in contact with the image carrier, and the layer thickness of the developer layer is A developing device comprising a leveling member for leveling the surface of the developer layer between a regulating member and a developing position, wherein the leveling member is configured to level the surface of the developer layer with respect to the rotating developer carrier. A developing device characterized in that the leveling member is held so as to be able to move toward and away from the developer layer, and the leveling member is brought into contact with the developer layer by rotational force due to the weight of the leveling member. (2) In claim 1, the surface of the developer is leveled at the tip edge of the leveling member, or the leveling member has a bend at its tip, and the tip edge of the bend A developing device characterized by leveling the surface of a developer layer. (3) Claims 1 or 2, wherein the rotational fulcrum of the leveling member is located at a position where a tip end edge of the leveling member contacts the surface of the developer layer. A developing device characterized in that it is located on the upstream side with respect to the rotational direction of a developer carrier. (4) A developing device according to any one of claims 1, 2, and 3, wherein the leveling member has an equalizing function when it comes into contact with the surface of the developer layer. . (5) A developing device according to any one of claims 1 to 4, characterized in that the charging series of the leveling member is between toner particles and magnetic particles.