JPH0293569A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a trace of a toner quantity detecting surface generating in an image by making the distance between a developer carrier and a developer quantity restricting surface different from the distance between a developing carrier and a detecting surface of a toner density detecting means. CONSTITUTION:The developer quantity restricting member 8 is provided near a sleeve 1 in a developer containing part 12, and on the same surface side as that of a restricting surface 8a, a translucent detecting surface member 13 is attached. Then the distance between the sleeve 1 and the developer quantity restricting member restricting surface 8a is made different from the distance between the sleeve 1 and the toner quantity detecting surface 13, and the toner quantity detecting surface 13 is brought closer to the sleeve 1. That is, the influence to the developer on the sleeve from the developer quantity restricting member 8 is made smaller by taking it away from the toner quantity detecting surface 13. Thus, even with developer quantity restricting member 8 and the toner quantity detecting window 13 of differing material and surface characteristics, by changing the distance from the sleeve 1, an image of good quality can be obtained stably over a long period of time without generating any unevenness in density of the image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus using an electrostatic recording process, such as an electrostatic copying machine or a printer, and particularly to a developing device thereof.

[Prior Art] In a well-known image forming apparatus that applies toner to a latent image formed on the surface of an image carrier and visualizes it, a so-called two-component developer in which a toner and a carrier are mixed is used as a developer. The products used have been widely used in the past.

In such devices, only the toner actually contributes to the visualization of the latent image, so the amount of toner gradually decreases in the developing device that stores the developer, resulting in a decrease in image density. I can't avoid doing it.

Therefore, in order to stably obtain good images, it is necessary to detect the amount of toner in the developer and replenish the toner appropriately.

Conventional toner concentration detection means to meet these demands include optical means that detects changes in reflectance depending on the amount of toner in the developer present in the detection area, and magnetic means that detects changes in magnetic permeability. A number of proposals have been made.

It has already been proposed to arrange a detection means near a developer carrier (hereinafter referred to as a sleeve) for supplying toner to a latent image on the surface of the image carrier. That is, the detection surface is arranged on the regulation surface of the developer amount regulation stage A.

This configuration is advantageous in that it is possible to detect the toner concentration in a portion of the developer in the developing device that immediately affects the visualization of the latent image on the image bearing member.

[Problem to be solved by the invention] However, if the material of the developer amount regulating member and the material of the toner amount detection surface are different, the degree of adhesion of toner to each member changes, and the developer regulation that contributes to development changes. A problem occurred in that the toner concentration of the developer after passing through the member or the amount of charge of the toner changed, resulting in marks on the toner amount detection surface or images.

This tends to occur not only due to differences in materials but also due to differences in surface properties.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for developing an image forming apparatus using a developer containing toner and a carrier by carrying the developer on a developer carrier. In the developing device that
The present invention is characterized in that the distance between the developer carrier and the developer quantity measuring member rF11 is not the same as the distance between the developer carrier and the toner concentration detection surface. With this configuration, even if the developer amount regulating member and the toner concentration detection surface have different materials and surface properties, the toner concentration of the developer after passing through the developer regulating member or the amount of charge of the toner can be made the same, A stable developing action can be achieved at all times without leaving any marks on the image on the toner amount detection surface.

[Example] FIG. 1 is a sectional view of a developing device to which the present invention is applied,
Inside the container extending perpendicularly to the plane of the paper, there is a toner storage section 2 containing a toner transporting member 3 whose operation is stopped at appropriate times by a control means (not shown), and a toner storage section 2 communicating with this through a mesh-like partition wall 4, and a transporting stirring screw. Developer storage section 1 having 5
1. A developer storage section 12 having a similar screw 6 and a rotating sleeve l made of a non-magnetic material containing a magnet roller la having a plurality of poles are formed and disposed through this and the partition wall 7. , the developer storage section 1
2, a developer amount regulating member 8 is disposed close to the sleeve l.

In addition, as shown in FIG. 2, the partition wall 5 that separates both screws has open lowers a and 7b formed at both ends thereof, and
The screw 5.6 is configured to feed developer containing non-magnetic toner and magnetic carrier in opposite directions, and the developer is transferred through the opening.

With this structure, part of the developer adhering to the sleeve is scraped off by the regulating member 8, and part of it is scraped off by the surface of the sleeve 1 and the surface 8a of the regulating member 8 facing the sleeve (regulating surface). ), the toner enters the gap with a constant density while rubbing the opposing surface, and then reaches the area facing the image carrier 10 where it is transferred to the latent image on the surface of the image carrier 10. It will become visible. In such a device, the illustrated device includes a detection means 1 on the regulating member 8.
4 is arranged.

FIG. 3 is a view seen from the direction of the white arrow X in FIG. The light-transmitting detection surface member 13 is attached to the same side as the restriction surface 8a.

A light source 15 is disposed inside the regulating member 8, and a part of the light beam is transmitted to the surface member 1 via the detection surface member 13 marked with #.
3 reaches the light receiving element 16, and the other part of the light flux directly reaches the light receiving element 17, so that output signals corresponding to the respective amounts of light are obtained.
As in a known device of this type, the two signals may be compared and the toner conveying member 3 may be activated to supply toner to the developer accommodating portion 11 until there is no difference signal.

With this structure, the developer fed to the developing area by the sleeve 1 while being regulated by the regulating member 8 is scraped off by the presence of the detection means, and the flow of the developer is disturbed. There is no risk that the toner will stick to the sleeve or the toner will stick to the sleeve, and it is possible to measure the toner concentration near the position where the developer performs development, eliminating false detection and resulting deterioration in image quality. can do.

In this example, a resin-coated ferrite carrier and a negatively charged non-magnetic toner were used as the developer.

At this time, in order to prevent negatively charged non-magnetic toner from adhering to the toner amount detection surface, a strongly negatively charged fluorine-based resin, specifically PFA (tetrafluoroethylene-fluoroalkyl vinyl ether copolymer), is used, and other developing agents are used. A molded ABS (acrylic butyl styrene) resin was used for the dosage regulating member. This resin is positively charged and causes the adhesion of negatively charged non-magnetic toner.

The distance d between the sleeve 1 and the developer amount regulating member regulating surface 8a
, and the distance between the sleeve l and the toner amount detection surface 13 is d2.
If d I = d z, toner does not adhere to the toner amount detection surface, but toner adheres to other developer amount regulating members, so the development after passing through the developer regulating member (so-called plate) The toner concentration of the agent also changed, which appeared as a phenomenon in which the image became darker only on the toner amount detection surface.

At this time, when we measure the amount of charge on the toner on the sleeve on the toner amount detection surface and the rest of the sleeve, we find that the amount of charge on the toner on the sleeve on the toner amount detection surface is slightly smaller than that on the other sleeves. It can be determined that the difference in frictional electrification between the amount regulating member and the toner amount detection surface also occurs in the image. (Specifically, the toner on the toner amount detection surface is approximately 20
Figure 3 shows the distance between the sleeve and the toner amount detection surface and the relationship between the sleeve and the developer relative to the image density. It shows the relationship of distance to the quantity regulating member.

From this result, as shown in Figure 2, dl is 2, Omad,
It became possible to erase the image traces on the toner amount detection surface by bringing the toner amount detection surface closer to the sleeve by adding 1.8 layers. This may be considered to be because the influence of the developer amount regulating member on the developer on the sleeve is reduced by moving it away from the toner amount detection surface.

Furthermore, since the toner amount detection surface can be brought closer to the sleeve, the sensitivity of the detection device has also been improved.

The above has described an example in which toner does not adhere to the material of the toner amount detection surface, but conversely, when toner is intentionally adhered to the toner amount detection surface and the toner concentration is detected based on the amount of toner, the above is reversed. The following configurations are possible. Specifically, the developer amount regulating member and the toner amount detection window were made of the same material, acrylic resin, and the surface was roughened by sandblasting to intentionally cause toner to adhere to the toner amount detection window.

In this embodiment, the image density can be made uniform by moving the toner amount detection surface of the developer amount regulating member away from the sleeve. Furthermore, due to the difference in surface properties, the distances between the developer amount regulating member and the toner amount detection surface to the sleeve may be changed sufficiently in advance. In other words, uniform image density can be maintained by placing the rougher surface, which has a higher frictional resistance against the developer, farther away from the sleeve than the smoother surface, which has a lower frictional resistance.

Although the present invention has been described above with reference to embodiments using optical detection means, the present invention is not limited thereto, and can be applied to other detection means such as magnetic means. This should be easy to understand.

[Effects of the Invention] The present invention provides stable high-quality images over a long period of time without causing density unevenness in images by changing the distance from the sleeve to the developer amount regulating member and toner amount detection window, which are made of different materials and surface properties. It is now possible to obtain images of Also, by bringing the toner amount detection window closer to the sleeve, the detection sensitivity can be further improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the developing device according to the present invention, Fig. 2 is a sectional view showing a developer storage section, and Fig. 3 is a relationship between the distance between the sleeve and the toner amount detection surface with respect to image density and the sleeve FIG. 4 is a cross-sectional view showing the configuration of the developer amount regulating member and the detection means. 1-... Sleeve 2... Toner storage portion 4.7-... Partition wall 5.6-... Agitation conveyance screw 8... Developer amount regulating member 13... Toner amount detection window 14... Detection Means 15... Light source 16.17... Light receiving element

Claims (1)

[Claims] In a developing device that uses a developer containing toner and carrier, toner concentration is detected on the side of the developer amount regulating surface facing the developer carrier of a developer amount regulating member disposed close to the developer carrier. In the developing device in which a detection surface of the toner concentration detection means is arranged, the distance between the developer carrier and the developer amount regulating surface is not the same as the distance between the developer carrier and the detection surface of the toner concentration detection means. Characteristic developing device.