JPH0225877A - Developing device for copying machines - Google Patents

Abstract

PURPOSE:To prevent a density in the central vicinity of an image from being light by giving a blade a curve shape reverse to a deflection curve generated since a blade edge faced to a sleeve is deflected in being pulled at a sleeve side in a uniform distributed load way by means of a magnet. CONSTITUTION:To the edge of a blade 3, a curve S is given at an ant-sleeve 2 side from the ideal line of the blade 3 edge from an ideal straight line A in which an interval between the blade 3 and sleeve 2 indicated by a broken line can be made linear. When the blade 3 is deflected in receiving the uniform distributed load magnetic force from the sleeve 2 by giving such a curve deltato the edge of the blade 3, the edge of the blade 3 is made to coincide with the ideal line A of the blade edge. Consequently, when the blade 3 receives the magnetic force form the sleeve 2, a distance between the blade 3 and sleeve 2 is made fixed anywhere. Thus, a density lowering in the image central vicinity generated since the thickness of a toner layer in the central vicinity is thinned can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device for copying machines, and more particularly, to an improvement of a blade for uniformly coating toner on a developing sleeve. .

[Prior Art] A conventional developing device of a copying machine or the like has a structure as shown in FIGS. 7 to 9, for example.

7 and 9, 11 is a frame, 12 is a sleeve, 13 is a blade, 14 is a blade support, 15
and 16 are screws.

That is, in the conventional development method, the blade 13 is fixed by supporting both ends with screws 16 that fix the blade support 14, and the distance between the blade 13 and the sleeve 12 is set so that the blade 13 is fixed. This is done using screw 15. Further, the conventional blade end shape is a straight line, as shown by A in FIG.

[Problems to be Solved by the Invention] In the conventional developing device described above, the blade 13 and the sleeve 1
Although the distance between the blades 2 and 2 can be adjusted using the screw 15, it can only be kept constant in the longitudinal direction of the sleeve 12. Therefore, the magnetic force from the sleeve 12 applies a uniformly distributed load of W, and at this time, the blade The end of 13 is the 8th
The equation for this deflection, which is deflected as shown in the deflection curve y in the figure, is expressed as follows.

However, E: Young's modulus ■＝Second moment of area j2 nispan distance W: Load per unit length x: 0~j! any position up to The maximum deflection is within the blade 13.

Due to this deflection, the distance between the blade 13 and the sleeve 12 becomes narrower at the center compared to both ends of the blade 13, and the thickness of the toner layer becomes thinner. Therefore, there is a problem that there is a shortage of toner near the center of the image, resulting in a low density.

The present invention attempts to solve these problems. That is, in the present invention, when the end of the blade facing the sleeve is pulled toward the sleeve with an evenly distributed load, the distance between the sleeve and the blade becomes uniform everywhere, and the thickness of the toner layer becomes uniform. The object of the present invention is to provide a developing device for copying machines.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a toner storage container, a sleeve rotatably provided on a developer container, a magnet held in the sleeve, and a magnet held in the sleeve. In a developing device for a copying machine, the blade is provided on the outside of the sleeve with a predetermined gap in order to coat and develop the toner to a predetermined thickness. A correction means is provided for correcting the blade end into a straight line by giving the blade a curved shape opposite to the deflection curve caused by being pulled toward the sleeve side in an evenly distributed manner by the magnet and deflected.

[Function] According to the present invention, the blade end facing the sleeve is given a curved shape opposite to the deflection curve caused by the magnet pulling the blade end toward the sleeve side with an evenly distributed load and deflecting. Since the linear correction means is provided, when the blade receives magnetic force from the sleeve, the distance between the blade and the sleeve is uniform everywhere, and the toner layer near the center of the blade is This prevents the thickness of the image from becoming thinner, and also prevents the density near the center of the image from becoming thinner.

[Embodiment] FIGS. 1 to 3 show a first embodiment of the present invention.

In FIGS. 1 and 3, reference numeral 1 denotes a frame that holds toner and supports each member. A sleeve 2 conveys the toner in the frame 1 to the photosensitive drum. 3 is a blade that makes the thickness of the toner uniform; 4 is a blade support that supports the blade 3; 5 is a screw for fixing the blade 3, and 6 is a screw for fixing the blade support 4.

In the above configuration, the toner in the frame i is adhered to the sleeve 2 and transported to the photosensitive drum for development.

At this time, as in the past, the thickness of the toner layer is set using the screw 5, but since it can only be made constant in the longitudinal direction of the sleeve 2, the blade 3 uses the magnetic force of the magnet of the sleeve 2 to set the thickness of the toner layer. It bends in the direction.

Therefore, as shown in FIG. 2, the curve shown by δ at the end of the blade 3 is connected to an ideal straight line A that makes a straight line between the blade 3 and the sleeve 2, as shown by the broken line in the same figure. It is applied to the side opposite to the sleeve 2 from the ideal line of the blade end.

This curve δ is obtained from the above equation (1), and the maximum value δmmK is obtained from the above equation (2). That is, . By giving such a curve δ to the end of the blade 3, when the blade 3 receives the uniformly distributed load-like magnetic force from the sleeve 2 and is bent, the end of the blade 3 becomes the ideal blade end as described above. It will match line A.

Therefore, when the blade 3 receives a magnetic force from the sleeve 2, the distance between the blade 3 and the sleeve 2 becomes constant everywhere, and the thickness of the toner layer becomes uniform, so that the density of the image becomes uniform.

4 to 6 show a second embodiment of the invention.

In this second embodiment, a gap adjustment screw for adjusting the gap between the blade 3 and the sleeve 2 is provided at one or more locations on the blade 3.

As described above, the blade 3 is pulled toward the sleeve 2 by the uniformly distributed magnetic force of the sleeve 2, and the blade 3 is deflected toward the sleeve 2. This situation is shown by the broken line y in FIG. As shown in the figure, the gap distance between the blade 3 and the sleeve 2 narrowed due to the deflection of the blade 3 is adjusted by applying the gap adjustment screw 7 against the blade support 4, and as shown in the figure P, the gap distance between the blade 3 and the sleeve 2 is adjusted. By forcibly changing the displacement in the opposite direction, the bent end of the blade 3 is aligned with the ideal line A of the blade end.
match. Further, at this time, by making the rotation of the gap adjustment screw 7 correspond to the amount of deformation of the end of the blade 3, the gap distance between the blade 3 and the sleeve 2 can be easily adjusted.

[Effects of the Invention] As explained above, according to the present invention, the blade end facing the sleeve has a curved shape opposite to the deflection curve caused by being pulled toward the sleeve side with an evenly distributed load by the magnet. Since there is a means for correcting the blade end into a straight line, when the blade receives a magnetic force from the sleeve, the gap between the blade and the sleeve becomes uniform everywhere; Therefore, the toner layer becomes uniform everywhere on the sleeve, and there is an effect of preventing a decrease in density near the center of the image due to the thinner thickness of the toner layer near the center.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the first embodiment of the present invention, Fig. 2 is an explanatory diagram of the blade in Fig. 1, and Fig. 3 is a section line A in Fig. 1.
4 is a perspective view showing the second embodiment of the present invention, FIG. 5 is a sectional view taken along cutting line B-B in FIG. 4, and FIG. An explanatory diagram of the blade, FIG. 7 is a perspective view showing an example of a conventional technique, FIG. 8 is an explanatory diagram of the blade in FIG. 7, and FIG. 9 is a sectional view taken along the cutting line C-C in FIG. 7. It is. 1... Frame 2... Sleeve 3... Blade 4... Blade support 5.6... Screw 7... Gap adjustment screw Figure 1 Figure 2 Figure 4 Figure 5. Figure 6

Claims (1)

[Claims] 1. A toner storage container, a sleeve rotatably provided in a developer container, a magnet held within the sleeve, and a predetermined magnet on the outside of the sleeve for coating the sleeve with toner to a predetermined thickness for development. In a developing device of a copying machine equipped with a blade provided with a gap of A developing device for a copying machine, characterized in that the developing device includes a correction means for correcting the blade end into a straight line by giving the blade a reverse curved shape.