JPS62209570A - Developping device for copying machine and the like - Google Patents

Abstract

PURPOSE:To prevent the influence of a developer mixed in an agitator, and to obtain a small type of developing device, by providing a small developer suppressing piece at a part of a doctor blade. CONSTITUTION:The developer in a developing bath 10 is moved while being mixed by the rotation of an agitating device 5 toward a doctor blade 1, however, the movement of the said developer toward the tip end part 1a direction of the doctor blade 1 is prevented by a developer suppressing piece 2. Undoubtedly, a suppressing function for the developer is effective even when the developer is agitated in the longitudinal direction of an axis 5 of rotation by a rotary blade 5b. Therefore, to the tip end part 1a of the doctor blade 1, the tuft of the developer which receives no influence of the developer agitated by the agitating device 5 is supplied, and the developer having a regulated thickness is supplied to an image carrying drum 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device such as a copying machine, and more particularly to the structure of a downsized developing device.

-Background of the Invention- Generally, in a developing device used for example in a copying machine,
After the developer is triboelectrically charged by a stirring device placed in the developer tank, the developer is magnetically attracted to the circumferential surface of the developing sleeve containing a permanent magnet, and the developer is slightly spaced apart from the circumferential surface of the developing sleeve. The agent is made to have a uniform thickness by a doctor blade, and is supplied to the image carrier.

Problems to be Solved by the Invention-" By the way, in such a developing device, when planning to downsize the developing device due to the demand for downsizing of the entire copying machine,
Although it is necessary to bring the stirring device close to the developing sleeve and the doctor blade, in such a structure, the developer mixed by the stirring device reaches the position of the doctor blade, which adversely affects the function of the doctor blade. In detail, the rotating stirring device stirs and mixes the developer with a single rotation blade, so in a structure in which the rotating blade is placed close to the doctor blade, the developer stirred by the rotating blade is a developer with a uniform thickness. The shadow of the developer that is being stirred has reached the tip of the doctor blade that forms the spike! As a result, the developer layer does not have the specified thickness. This phenomenon is caused by the coarse density of the developer being stirred far from the doctor blade position, as the rotating blade is tilted with respect to its rotation axis for mixing of the developer, and even at the tip of the doctor blade. Since the pressure state of the developer changes over time, it becomes impossible to obtain a uniform thickness of the developer spike in the length direction of the developing sleeve.

It is an object of the present invention to take into account the problem of miniaturization of the conventional developing device as described above, and to apply a developer of a specified thickness to the circumferential surface of the developing sleeve without being affected by the developer being stirred. The goal is to obtain a structure that can form panicles.

Means for Solving a Problem - In order to achieve this object, the present invention adsorbs the developer charged with an adjacent stirring device to the circumferential surface of a developing sleeve, and provides a developer sleeve facing the same circumferential surface. In a developing device such as a copying machine that forms developer spikes of uniform thickness using a blade, the doctor blade is supported in a cantilevered state on the agitation device side, and the tip is extended from the circumferential surface of the developing sleeve to the tip of the doctor blade. It is proposed to provide spaced apart rigid developer deterrent strips.

One Embodiment - An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The illustrated embodiment is characterized by a developer deterrent piece that is cantilevered at a portion near the tip of the doctor blade.

In the illustrated example, the doctor blade l is made of an elongated extruded material in a direction perpendicular to the drawing, and both ends of the doctor blade l fall into a positioning recess 10B formed on the inner surface 10A of the end wall of the developer tank lO, and are screwed into the developer tank by screws 11. It is fixed at 10.

The positioning recess 10B is a recess formed in the inner surface 10A of the end wall of the developer tank 10 at a position corresponding to the developer layer thickness regulating part, and includes a positioning surface 10a.

This positioning surface 10a is the tip 1 of the doctor blade 1.
The position of the doctor blade 1 can be adjusted in the radial direction of the developing sleeve by determining the gap between a and the circumferential surface of the developing sleeve 3, which will be described later.

As shown in an enlarged view in FIG. 2, the developer deterrent piece 2 provided at the portion near the tip la of the doctor blade l is placed in a cantilevered state on the stirring device 5 side, the details of which will be described later, and is made of a rigid material. The doctor blade 1 is placed between the tip of the developer suppressing piece 2 and the circumferential surface of the developing sleeve 3 so as not to adversely affect the ears of developer magnetically attracted to the circumferential surface of the developing sleeve 3. This is larger than the gap between the tip and the circumferential surface of the developing sleeve 3.

The developing sleeve 3 is a well-known magnetic brush developing sleeve that includes a built-in magnet for forming a magnetic brush, and rotates counterclockwise to convey the developer to the image carrier drum 4 .

Further, as shown in the third figure, the stirring device 5 is driven to rotate in the direction of the arrow, and a plurality of rotating blades 5b are arranged on both sides of the rotating shaft 5a with the axial center as a border. It is tilted in opposite directions to the axial direction.

Since the illustrated embodiment has one or more structures, the image carrier drum 4, the developing sleeve 3, and the stirring device 5 are each driven to rotate in the direction of the arrow when the copying machine or the like is in operation. Therefore, the developer charged by the Wl agitation device 5 is magnetically attracted to the circumferential surface of the developing sleeve 3, becomes a specified developer spike while passing the position of the doctor blade 1, and is transferred to the image carrier. The electrostatic latent image on the surface of the drum 4 is developed. When this developing device is operated, the developer in the developer tank 10 moves toward the doctor blade 1 while being mixed due to the rotational movement of the stirring device 5. The developer is prevented from moving toward the tip 1a of the doctor blade l by the developer deterrent piece 2.Of course, this developer deterrent action is caused by the rotary blade 5b.
This works effectively even if the developer is stirred also in the longitudinal direction of the rotating shaft 5a. For this reason, the tip 1 of the doctor blade 1
Since spikes of developer that are not affected by the developer stirred by the stirring device 5 are supplied to a, the image carrier drum 4 is supplied with developer having a specified thickness.

In the above embodiment, a developer deterrent piece integrally formed with the doctor blade was illustrated, but it goes without saying that a developer deterrent piece manufactured separately from the doctor blade may be fixed to the doctor blade. .

Effects of the Invention - As is clear from the above description, according to the present invention, the influence of the developer mixed by the stirring device is prevented by simply providing a small developer-suppressing piece on a part of the doctor blade. Therefore, a compact developing device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a developing device according to the present invention. FIG. 2 is an enlarged sectional view of essential parts of the developing device, and FIG. 3 is a plan view of an agitation device used in the developing device according to the present invention. DESCRIPTION OF SYMBOLS 1...Developing sleeve, 2...Developer prevention piece, 3...Developing sleeve, 5...Agitation device.

Claims (1)

[Claims] 1) In a developing device such as a copying machine, in which developer charged with a nearby stirring device is adsorbed onto the circumferential surface of a developing sleeve, and a doctor blade facing the same circumferential surface forms developer spikes of uniform thickness. , a copying machine comprising a rigid developer deterrent piece supported in a cantilevered state on the stirring device side of the doctor blade and having a tip portion spaced apart from the circumferential surface of the developing sleeve relative to the tip of the doctor blade. Developing equipment such as