JPH0435901Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a developing device for a copying machine, a printer, etc. that uses an electrophotographic method.

[Background of the idea]

Being able to use the developing device in an inclined position gives greater flexibility in the structure and installation of copiers and printers, but in conventional developing units, the developer tends to be unevenly distributed, so it is necessary to use the developing unit in an inclined position. I couldn't do that.

Generally, a developing device is equipped with a scraping member made of a rectangular plate, and is used to carry the developer scraped off from the magnet roll to a position where the magnetic force is so weak that it cannot be attracted to the magnet roll again. There is. There are also types that have blades on the scraping plate to cause the developer to flow in the axial direction of the magnet roll, and types that have multiple scraping plates, and these also use the scraping plate as an agitator. It is.

Now, the problem when the developing device is installed in an inclined state is that the developer is biased towards the lower side of the slope.
The problem is that the developer cannot be supplied to the magnet roll in time in the upper part, and some parts cannot be developed. Therefore, if you try to use the blades of the scraping plate to correct the misalignment, there will be a part with less developer on the back side of the blade, and on the front side, the developer flow will be smooth because the forced flow is changed parallel to the direction of the blade. This causes the developer to become dense and uneven, resulting in uneven development.

Furthermore, if the scraping plate is inclined, the end facing the magnet roll must be curved to match the outer circumferential curved surface of the magnet roll, making processing and installation cumbersome.

On the other hand, as an agitator, there is a device that uses a screw and rotates the screw to agitate the developer. The agitator using this screw creates a flow of developer in the axial direction of the magnetic roller for development, so the conveyance force of the agitator suppresses the deviation of the developer due to the inclination, and the adaptability to the inclination ( (allowable slope) can be increased. However, when this is used to correct the deviation of the developer, it is difficult to optimally design it because the influence of the magnetic field of the magnet roll is large. Even if the optimum shape is determined experimentally, it is extremely difficult to manufacture the optimum shape due to many manufacturing constraints such as the drive source, gear, size of the developing device, screw pitch, etc.

These problems are noticeable in the case of small-sized developing devices that can accommodate only a small amount of developer, and can be relatively easily addressed in large-sized developing devices by increasing the amount of developer that can be accommodated. can. In addition, as related to such a device, for example, Japanese Patent Publication No. 49-36618, Japanese Patent Application Laid-Open No. 55-26541,
Examples include JP-A-58-207063.

[Purpose of invention]

An object of the present invention is to improve the adaptability to the inclination of the developing device with a simple structure by devising the shape of the scraping member and changing the flow of the developer.

[Summary of the idea]

The present invention utilizes development in which when the developer falls from the edge of a plate-shaped scraping member, the direction of the flow is perpendicular to the falling edge, and the magnetic roll of the scraping member is opposed to the developer. The side end edge is parallel to the magnet roll axis and opposite to the magnet roll axis, and the developer falling area on the opposite side is arranged so as to form a continuous side that is not parallel to the magnet roll axis. The width from the opposite edge is continuously changed, and the inclination of the falling edge with respect to the magnet roll generates an axial flow component in the developer falling from the falling edge. .

[Effect of idea]

An embodiment of the present invention will be described below. Figure 1 is an extracted diagram of the paper feeding section and printing section of a laser beam printer, which uses an electrophotographic method. Second
The figure is a sectional view of the developing device 5. In this developing device 5, the developer 22 is frictionally charged by the stirrer 23, and is attracted to the magnet roll 20 by the magnetic force of the magnet roll 20 to form a magnetic brush.
The electrostatic latent image on the photoreceptor 1 is used as a toner image. After development, the developer 22 is transferred to the magnet roll 20 by a plate-shaped scraping member 21 in order to sufficiently charge the developer 22 again.
The scraped material is scraped off from the surface, and is allowed to flow on the slope of the scraping portion 21 until it reaches a position where it can be sufficiently stirred without being adsorbed by the magnet roll 20 again, and falls to the bottom of the developing chamber, and the stirring and development are repeated again. The developer 22 may be a two-component developer or a one-component developer. FIG. 3 is a cross section of the developing device 5 with the magnet roll exposed.

In this developing device 5, the two agitators 23 are rotated in opposite directions to convey the developer 22 from side to side.
The conveying force of the agitator 23 is designed to minimize the deviation of the developer 22 to the left and right depending on the pitch and rotation speed of the screw, but it is difficult to calculate the flow and there are manufacturing constraints on the dimension settings. In the actual developing device, there is uneven development of the developer. this is,
It does not appear when the developing device is horizontal, but becomes noticeable when the developing device is tilted. The degree of deviation of the developer differs depending on whether the developer is tilted to the right or the left, resulting in a developing device that is weak against tilt (allowable tilt is small).

To prevent this, as shown in Figure 4,
The width of the scraping member 21 is changed by cutting the developer falling end side of the scraping member 21 on the side opposite to the magnet roll 20 obliquely with respect to the axis of the magnet roll. As shown by the arrow in FIG. 5, the developer 22 tries to change its flow in a direction perpendicular to the developer falling edge. Although the cutting direction is not actually perpendicular due to the inertia of the developer 22, experiments were conducted using the scraping member 21 at various angles, and the cutting angle of the scraping member 21 was determined from the experimental results. This corrects the movement of the developer 22 caused by the agitator 23 to make it uniform on the left and right sides, and as a result, the movement when tilting on the left and right sides is made equal, thereby improving the tilt condition (allowable tilt degree) when using the developing device 5. I let it happen. This has made it possible to provide a laser beam printer with improved tilting conditions during use.

FIGS. 6 to 8 show modified examples of the scraping member 21, but it is possible to create a flow in several directions or change the flow in only a part depending on the characteristics of the developing device 5 and the characteristics of the agitator. You can also do it.

FIG. 9 is an example in which a similar effect is obtained by utilizing creases caused by bending.

[Effect of idea]

According to the present invention, an axial component can be generated in the flow of the developer with a simple configuration in which the developer falling edge of the plate-shaped scraping member is made non-parallel to the magnet roll axis. . Moreover, this axial component becomes continuous by making the developer falling end side a continuous side, and it is possible to prevent the occurrence of uneven distribution of the developer.

Furthermore, if the scraping member itself is inclined with respect to the magnet roll axis, the end side facing the magnet roll must be curved in order to fit the outer circumference of the magnet roll. Since the end sides are parallel to the magnet roll axis, there is no need to do so, and shape management does not become troublesome.

In a conventional developer using a scraping member, the present invention can be implemented by simply changing the shape of the member, and it is easy to apply the present invention to an existing developer.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a printer according to an embodiment of the present invention.
Figure 2 is a cross-sectional view of the developer in the direction perpendicular to the magnet roll axis, Figure 3 is an internal view of the developer in the direction of the magnet roll axis when the developer is tilted, and Figure 4 is a top view of the developer. , FIG. 5 to FIG. 9 are also shape diagrams of embodiments of the scraping member. 1...Photoreceptor, 5...Developer, 20...Magnet roll, 21, 21B, 21C, 21D, 2
1E... Scraping member, 22... Developer, 23...
…mixer.

Claims (1)

[Scope of utility model registration request] A magnet roll installed horizontally in a developing chamber, a powdered developer that is attracted to the circumferential surface of the magnet roll to form a magnetic brush and develop an electrostatic latent image, and a circumferential surface of the magnet roll. In the developing device, the scraping member includes a scraping member that scrapes off the developer from the developer and an agitator installed at the bottom of the developing chamber, wherein the scraping member is a plate-shaped member, and the magnetic roll of the plate-shaped member The opposite end side is parallel to the magnet roll axis and opposite to the magnet roll, and the developer falling end side on the opposite side forms a continuous side that is not parallel to the magnet roll axis. A developing device having a scraping member characterized in that the width from the opposite end side is continuously changed.