JPS604185Y2 - developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device that always provides good images with sufficient image density regardless of temperature fluctuations.

In recent years, a one-shot development method that does not require a complicated and expensive density adjustment device and has a simple mechanism has been put into practical use.

A simple and inexpensive device using such a developing method can maximize its advantages by always exhibiting constant performance in the temperature range where humans live.

However, if you look at the equipment that actually exists, for example, -5℃
There are almost no methods that can provide good images over a temperature range of ~35°C.

Experiments conducted by the inventors of the present invention revealed that the image density decreases particularly at low temperatures.

That is, under low temperature conditions, the toner layer coated on the sleeve becomes extremely thin, resulting in images with insufficient image density.

In view of these circumstances, it is an object of the present invention to provide a simple and novel developing device that provides good images that are not affected by temperature fluctuations.

To summarize the present invention, by providing an abutment part that can slide with the sleeve outside the developing area of the doctor blade that regulates the toner layer, the gap distortion between the doctor blade and the sleeve due to temperature fluctuation is ignored. To the extent possible,
The regulated toner layer thickness is made substantially uniform to provide a good image that is not affected by temperature fluctuations.

Hereinafter, embodiments of the device according to the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a conventionally proposed developing device.

An electrostatic latent image is formed on the photosensitive drum 1, which rotates in the direction of the arrow.

The sleeve 2 conveys the toner 4 regulated to a predetermined thickness by a doctor blade 3 to a portion close to the drum 1 and develops it.

The hopper wall 5 forms a toner hopper together with the blade 3 which also serves as a hopper wall.

In the device having such a configuration, the doctor blade 3 is fixed to the side wall of the hopper (not shown), the sleeve shaft (not shown), or to the outside of the device.

The fixing or supporting method that is not recommended is that the gap between the sleeve and the blade changes greatly due to thermal expansion or contraction due to temperature changes in the hopper wall, sleeve, and doctor blade, and the coating layer thickness changes accordingly. do.

This effect manifests itself in a significant reduction in image density, especially when limitations in the development method require a reduction in coating layer thickness, ie, a reduction in the sleeve-blade gap.

In an experiment conducted by the authors, when a stainless steel blade was fixed to a polycarbonate side plate, the desired setting value was 1.
-58C to 3 for a sleeve-blade gap of 00μ
With a temperature change of 5°C, a sleeve-blade gap change of 20μ to 150μ was observed.

Furthermore, by using molding materials to reduce costs,
Due to its large coefficient of thermal expansion, variations in the sleeve-blade gap become increasingly large.

In addition, although it may be easy in concept to provide complicated additional means to solve such drawbacks, it is not desirable from the viewpoint of production and maintenance.

FIG. 2 shows an embodiment of the developing device according to the present invention.

The drum 1, sleeve 2, toner 4, and hopper wall 5 are the first
It is the same as the figure.

The doctor blade 3 has a shape as shown in FIG. 3 when viewed from the drum surface side, and the sliding surface 6 as a position setting portion contacts the surface of the sleeve 2 at both ends where toner coating is not necessary. , the distance between the toner discharge surface 7 of the doctor blade 3 and the surface of the sleeve 2 is maintained.

The elongated hole 8 formed in the side surface of the doctor blade 3 is only movable in the vertical direction by a protrusion or claw (not shown) from the side.

In such a configuration, the change ΔL in the sleeve-blade gap due to temperature is such that the thermal expansion coefficient of the sleeve 3 is a1, the temperature difference is t
Then, it is expressed as ΔI,=Lat.

-5°C to 35°C, temperature difference 40°C, initial setting gap L
= 100 μ, and a is at most 200 to 30 even for polymeric materials.
Since 0x 10-6/'C, ΔL is ΔL=0.8~1
．． It is 2μ, which is about 1% of L, so it can be almost ignored.

Yet another embodiment of the present invention is shown in FIG.

A fixed magnetic roller 11 is housed in the rotating sleeve 2, and the blade 3 is fixed in the front wall 10 of the hopper with a pin 9 in an elongated hole 8, as shown in FIG.

The blade 3 is a magnetic material and is attracted to the magnetic pole N of the magnet 11.
The contact surface 6 as a positioning part of the blade 3 on the sleeve 2 is in reliable contact with the sleeve surface.

It is very effective to apply lubricant to the sliding parts of the sleeve and blade.

Examples of the present invention will be described below.

- Coat a component magnetic toner on a sleeve, apply a bias potential to the sleeve in close proximity to an electrostatic image-bearing drum, and cause said toner to be attracted by an electric field formed by such potential and an electrostatic image potential on the drum. In the so-called jumping development method, in which a toner image is obtained by flying the toner, the gap between the sleeve and the photosensitive drum is approximately several 100 microns to ensure that the toner flies. It needs to be small.

This developing method produces very good images without blurring, but since the toner is thinner, if the blade is easily attached to the molded member, the mechanism described above will cause
Large toner layer thickness changes occur with temperature changes.

In the configuration shown in Figure 4, the present inventors used polycarbonate for the stainless steel blade, the bottle with a sleeve-blade gap of 150 μm, and the hopper. We were able to obtain stable images.

The present invention is not limited to the embodiments and examples described above, but can also be applied to the development of other latent images, such as magnetic latent images (in this case, the magnetic field by the developing magnetic pole is substantially magnetic). (It is necessary to ensure that they are not too close together so as not to affect the latent image on the latent image carrier.)

As described above, the present invention provides a developing device having a developer support means 2 provided opposite to a latent image maintenance means and a means 5 for supplying developer onto the developer support means. A developing device characterized in that a developer layer thickness regulating means 3 having a position setting part 6 always in contact with the surface is provided, and a developer layer having a uniform thickness always is formed on the developer supporting means against temperature changes. Therefore, it has the effect of forming a uniform developer layer and forming stable and high-quality visible images over the usage environment temperature range, for example, from -5°C to 35°C. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a schematic configuration of a conventionally proposed developing device, FIG. 2 is an explanatory diagram of a configuration of an embodiment of the developing device according to the present invention, and FIG. 3 is a plan view of its developer layer thickness regulating means. , 4th
The figure is a structural explanatory diagram of another embodiment of the developing device according to the present invention, and FIG. 5 is a plan view of the developer layer thickness regulating means. 2...Developer supporting means, 3...Developer layer thickness regulating means, 4...Developer, 6...
Position setting section.

Claims (1)

[Scope of utility model registration request] A developing device that performs development by supplying a developer from a developer supplying means to a developer supporting means provided opposite to a latent image holding means, wherein the layer thickness of the developer is adjusted in the vicinity of the developer supporting means. A regulating means is provided, and both ends of the regulating means are made to protrude to form a position setting section, and this position setting section is always brought into contact with the surface of the developer supporting means, whereby the regulating means and the developer supporting means are controlled. A developing device characterized by maintaining a predetermined gap between the developing device and the developing device.