JPH0194370A - developing device - Google Patents

Abstract

PURPOSE:To obtain an excellent image which has neither an irregularity nor white part by easily coating a developer carrier with a uniform thin layer by utilizing the napping and unbinding of a developer in the narrow space formed of a control member and the developer carrier. CONSTITUTION:The control member 6 forms a contact part which abuts on a developing sleeve 2, one pole 3a of a magnetic field producing means 3 is at a corner position corresponding to a magnetic plate 5, and the magnetic field area formed by the pole 3a and magnetic plate 5 is present in the wedgelike narrow space 8 formed by the contact part 9 on an upstream side in the rotating direction of the developing sleeve 2. The developer carried on the developing sleeve 2 with lines of magnetic force are napped without cohesion and unbound effectively in the narrow space 8, so that a uniform and thin layer of the developer is formed on the developing sleeve. Consequently, an image of good quality having no irregularity is formed.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is utilized in the technical field of developing devices used in electronic copying devices, and is particularly applicable to various types of display devices for image recording, printers, and facsimile electrophotographic devices. The present invention relates to a developing device applicable to the device.

(Prior Art and Problems) A fixed magnetic field generating means is disposed inside a rotatable cylindrical developer carrier made of a non-magnetic material, and the magnetic force generated by the magnetic field generating means is applied onto the developer carrier. The developer transported toward the developing section while being held by the developer is regulated to a predetermined layer thickness by the contact pressure of a regulating member such as a thin rubber plate, and then transferred to the electrostatic latent image carrier in the developing section to form the image. 2. Description of the Related Art A developing device that develops an electrostatic latent image on a carrier is known.

However, in this type of device, 1 the above-mentioned regulating member is usually provided with a thin rubber plate or the like that contacts the circumferential surface of the developer carrier, and the contact portion is formed between a roughly square-shaped constriction. It is supposed to form. Therefore, as the developer carrier rotates, the developer carried thereon tends to become clogged between the wedge-shaped narrow spaces due to the pressure of the regulating member.

As a result, the amount of developer transported by the developer carrier decreases, making it extremely difficult to form a uniform thin layer of developer.
In even worse cases, there is a problem in that the developer is not transported at all, resulting in vertical white stripes on the image.

In particular, the above-mentioned problem is noticeable in a high-temperature environment due to the nature of the developer.

As a countermeasure for eliminating the above-mentioned white streaks, a light pressure leveling member is again installed on the developer coated layer on the surface of the developer carrier after being regulated by an elastic regulating member. Also,
There is also a configuration in which vibration is applied to the resistance regulating member or it is caused to perform reciprocating motion. However, all of these devices have complicated device configurations, and the current situation is that they have not been able to achieve sufficient effects.

(Means for Solving the Problems) An object of the present invention is to solve the above-mentioned problems and provide a developing device capable of obtaining uniform, high-quality images.

In order to achieve the above object, the present invention provides a rotatable developer carrier that transports developer on its surface by the magnetic force of a magnetic field generating means fixedly arranged in an internal space.
The developer container is arranged so as to partially protrude from the front opening of the developer container in which the developer is stored, and the protruding portion of the developer carrier is brought close to or in contact with the electrostatic latent image carrier. In a developing device in which the developer carrier and the electrostatic latent image carrier are installed in parallel, an outlet side portion of the developer carrier in the opening of the developer container is brought into contact with the surface of the developer carrier. A regulating member that forms a contact portion and regulates the thickness of the developer layer on the surface, and the regulating member and the developer carrier are arranged upstream of the contact portion in the rotational direction of the developer carrier. The magnetic field region is formed between a constriction formed on the side or between one of the magnetic poles of the magnetic field generating means and a magnetic body disposed outside the developer carrier.

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

FIG. 1 shows a developing device according to a most preferred embodiment of the present invention. The developing device according to this embodiment will be explained by taking a developing device using Carlson electrophotography as an example, and since its overall configuration is already well known, it includes a developing sleeve as a developer carrier according to the present invention, and a developing device using the Carlson electrophotography method. The regulating member and the like that come into contact with the sleeve are illustrated in detail, and illustrations of the primary charging means, exposure means, cleaning means, etc. in the Carlson process are omitted.

In FIG. 1, an electrostatic latent image carrier, that is, a photosensitive drum 1, is rotatably supported in the direction of arrow A, and a developing device is disposed near the outer edge of the photosensitive drum 1. .

For example, OPC
Well-known materials such as
An electrostatic latent image is formed by a charging means, an image exposure means, etc. which are already known.

The developing device has a developer container 4 having an opening on the front surface and containing a one-component or two-component developer therein, and is disposed partially protruding from the developer container 4 with a gap on the photosensitive drum l. It has a developing sleeve 2 which is a rotatable developer carrier facing the opening, and a regulating member 6 made of a non-magnetic thin plate and elastically in contact with the developing sleeve 2. Furthermore, inside the developing sleeve 2, Four magnetic poles: la,:
A magnetic field generating means 3 having lb, 3c, 3d is fixedly arranged.

The regulating member 6 is formed of a thin elastic plate made of urethane rubber, for example, and is attached to the magnetic plate 5 provided at the upper edge of the opening of the developer container 4 . Further, the regulating member 6 is
It forms a contact portion with the developing screen 2, and one pole 3a of the magnetic field generating means 3 is located at an angular position corresponding to the magnetic plate 5. Therefore, as shown in an enlarged view in FIG. There is a magnetic field region created by this. Note that the lines of magnetic force are shown in FIG. 2 as broken lines. Due to these lines of magnetic force, the developer carried by the developing sleeve 2 does not aggregate and forms spikes.

That is, the developer is effectively loosened within the narrow space 8, and it becomes possible to form the developer in a uniform and thin layer on the developing sleeve. Further, since the developer having a small amount of electrical charge that is transported into the narrow space 8 has a weak adhesion force to the developing sleeve 2, it is magnetically restrained within the narrow space 8. The restrained developer falls partially due to gravity in a direction a opposite to the developing sleeve moving direction B and is returned. Further, some of the developer overcomes the magnetic binding force and is transported to the contact portion 9 between the regulating member 6 and the developing sleeve 2, especially the developer having an amount of electrical charge equal to or higher than a predetermined level. At the contact portion 9, the conveyed developer is given a static charge. Therefore, the developer coated layer on the developing sleeve 2 that has passed through the contact portion 9 becomes uniform and has a uniform charge distribution.

Next, a specific example with numerical values for this embodiment will be shown. In this example, in the form shown in FIG. 2, the magnetic force of the magnetic pole 3a was set to 700 Gauss, and the distance between the developing sleeve 2 and the end of the magnetic plate 5 was set to 4+*s. The diameter of developing sleeve 2 is 20
I am humble. For the regulating member 6, a urethane rubber plate (rubber hardness 65°, thickness 1.slIm) is used, and the free length (the length of the part hanging from the end of the magnetic plate) is set to 61cm to make it magnetic. It was stuck to the plate 5. The pressing force of the regulating member 6 on the developing sleeve 2 at the contact portion 9 is 50 g/cm per unit length of the developing sleeve in the longitudinal direction. Further, since the regulating member 6 is fixed to the magnetic plate 5 and inside the body, the above-mentioned stenotic space 8 can be easily formed, and the magnetic field according to the present invention works effectively within the stenotic space 8. It happens.

The present invention can be practiced even if the contact form of the regulating member and the type and shape of the magnetic plate are changed.

Hereinafter, these will be explained as other embodiments based on FIG. 3 and subsequent figures. However, in order to avoid complication of explanation in the drawings, common parts are given the same reference numerals and detailed explanations are omitted.

FIG. 3 shows the contact form of the regulating member 6 opposite to that in FIG. 1.
This is an embodiment in which the developing sleeve 2 is brought into contact in a counter direction with respect to the rotating direction, and FIG. 4 is an enlarged view of only the main parts of the vicinity of the contact portion in FIG. 3.

In FIG. 4, similarly to FIG. 2, the developer stands up due to the magnetic field generated between the magnetic pole 3a and the supporting magnetic plate 5, and the developer loosens within the narrow space 8. This bristling causes a necessary and sufficient amount of developer to be conveyed through the contact portion 9, resulting in a good image with no unevenness.

FIG. 5 shows an embodiment of a developer application device in which a regulating member 6 attached to a non-magnetic support plate 5A is sandwiched between a magnetic pole 3a and a magnetic plate 5B.

As shown in FIG. 5, if the magnetic plate 5B is supported so that sufficient spikes of the developer occur in the narrow spaces 8, the same effect as shown in FIG. 4 will occur, and the unevenness will also be reduced. You will be able to get a good image.

FIG. 6 shows an embodiment of the developer coating device in which the non-magnetic support plate 5A in FIG. 5 is replaced with a magnetic support plate 5A'.

If the apparatus is constructed as shown in FIG. 6, the developer will first be caused to stand up by the magnetic force generated between the magnetic pole 3a and the magnetic support plate 5A', and will be sufficiently loosened. Thereafter, the same effect as shown in FIG. 5 occurs due to the magnetic force generated between the magnetic plate 5B and the magnetic pole 3a, making it possible to obtain a good image with even partial unevenness.

Note that the regulating member is not limited to this embodiment, and its material and shape can be changed depending on design specifications and the like. Moreover, the setting of the regulating member is not limited to this embodiment, and may take other forms.

(Effects of the Invention) According to the above-described invention, the developer carrier can be moved to The effect is that a uniform thin layer can be easily applied on the surface, and a good image without unevenness or white spots can be obtained. In addition, a predetermined amount of triboelectric charge is uniformly applied to the developer, making it possible to form a thin layer of developer with a uniform charge distribution.As a result, images with no fog and good gradation can be produced. The effect of being able to obtain a copy image with sufficient density is also obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an outline of a device according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the vicinity of the contact part of the device shown in FIG. 1, and FIG.
The figure is a cross-sectional view showing the outline of another example device, and FIG.
FIG. 5 is an enlarged cross-sectional view showing the vicinity of the contact part of the apparatus, FIG. 5 is a cross-sectional view of the vicinity of the contact part of still another embodiment, and FIG. 6 is a cross-sectional view of the vicinity of the contact part of still another embodiment. 1-------... Electrostatic latent image carrier (photosensitive drum) 2
......Developer carrier (developing sleeve) 3.
......Magnetic field generating means 3a...Magnetic pole 4...Developer container 6...Regulation member 8...・・・・・・Representative of Canon Co., Ltd., applicant for inter-stenotic patent
Person Patent Attorney Meien Fujioka 1 Figure 2 Figure ζ Figure 3 Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) A rotatable developer carrier, which conveys developer on its surface by the magnetic force of a magnetic field generating means fixedly arranged in the internal space, is moved from the front opening of the developer container containing the developer. The developer carrier is arranged in the container so as to partially protrude, and the protruding portion of the developer carrier is brought close to or in contact with the electrostatic latent image carrier so that the developer carrier and the electrostatic latent image carrier are parallel to each other. In the installed developing device, a contact portion that comes into contact with the surface of the developer carrier is formed on the outlet side portion of the developer carrier at the opening of the developer container to control the thickness of the developer layer on the surface. A narrow space formed by the regulating member and the developer carrier on the upstream side of the contact portion in the rotational direction of the developer carrier is provided with a regulating member for regulating the magnetic pole of the magnetic field generating means. A developing device, characterized in that the developing device is located in a magnetic field region formed between a developer carrier and a magnetic body disposed outside the developer carrier. (2) The developing device according to claim (1), wherein the regulating member is attached to a magnetic body. (3) The developing device according to claim (1), wherein the regulating member is formed of a non-magnetic thin plate having elasticity.