JPH0486850A - Developing device - Google Patents

Abstract

PURPOSE:To supply only toner which is electrostatically charged to a developing sleeve, to restrain toner scattering and fogging at a developing stage in a developing area and to prevent the contamination of a periphery and the stain of an image by providing an electret layer having a reverse polarity to the toner on a supply roller. CONSTITUTION:By the rotation of the developing sleeve 1, the toner T which is electrostatically stuck to the electret layer E of the supply roller 2 and rotated to be supplied is successively peeled from the roller 2 side by a contact surface and carried to the developing area 6, and it is electrostatically attracted to a latent image on a photosensitive drum 5, which is developed. At such a time, the toner T is all electrostatically attracted to the latent image and is not scattered to the periphery because only the toner T which is electrostatically charged exists. Since the toner T which is not electrostatically charged does not exist, the toner T is not stuck to the part of the drum 5 where the latent image does not exist and the fogging phenome non does not occur. The electret is the material of high polymer which semipermanently maintains an electric polarization state at high voltage, and the material itself maintains the polarity even though a power supply circuit for applying bias voltage is not connected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device, and more particularly to a developing device for supplying toner for development to a photosensitive drum of an image forming apparatus.

[Prior Art] Conventionally, in a non-magnetic component developing device, for example, there is an invention disclosed in Japanese Patent Application Laid-Open No. 60-53975, which uses a rotating system to which a bias voltage is applied by a bias power source B, as shown in FIG. In order to be able to sufficiently supply the toner T to the main developing sleeve 1, a sub rotatable supply roller 2 is provided. The concentration of toner T supplied to the photoreceptor tram 5 is maintained.

[Problems to be Solved by the Invention] However, in the conventional example, the sub-supply roller 2 supplies the toner T to the developing sleeve 1 using mechanical adhesion force rather than electrostatic adsorption force.

Therefore, unnecessary uncharged toner is mixed into the developing sleeve 1 and conveyed to the developing area 6, and when the charged toner flies toward the latent image on the photoreceptor tram 5, the uncharged toner scatters. There were issues such as surrounding contamination and image smearing due to fog. The present invention aims to solve such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides the following developing device.

That is, the present invention is a developing device including a supply row that supplies toner to a developing sleeve and an electret layer having a polarity opposite to that of the toner.

[Operation] In the above configuration, since the electret of the supply roller has a polarity opposite to that of the toner, it electrostatically attracts only sufficiently charged toner and supplies it to the developing sleeve, and does not supply uncharged toner.

[Embodiments] With regard to embodiments of the present invention, the structure and actual embodiment of the present invention will be described below with reference to the drawings, along with their effects.

FIG. 1 is an explanatory diagram of one embodiment of the present invention. In the figure, 1 is a rotatable main developing sleeve.
A rotatable sub-supply roller 2 that supplies toner T to
A layer of electret E having a polarity opposite to that of the toner T is provided on the outer periphery of the supply roller 2 .

This electret is a polymeric material that can semi-permanently maintain an electrically polarized state at a high hortane.For example, the material itself can maintain its polarity even without connecting a power supply circuit that applies a bias voltage. It is said that the name electret was given to magnets because it resembles a permanent magnet or magnetic poles that can be maintained for a long period of time.

Electret has an extremely simple structure, is light and compact, and as technology advances in the polymer field, it has recently become a material commonly used in audio equipment such as ultra-compact microphones and speakers.

A blade 3 made of an elastic member such as rubber is disposed on the developing sleeve 1, and its tip 3a limits the toner T adhering to and conveying onto the developing sleeve 1 to a constant thickness.

These developing sleeve 1, supply roller 2, and plate 3 are
Each of them is attached within the main body 4 of the developing device.

A rotatable photoreceptor tram 5 is adjacent to the outside of the main body 4 of the developing device, and toner T is supplied from the developing device via the developing sleeve 1 to cause the toner on the photoreceptor tram 5 to be It visualizes a latent image.

That is, the latent image on the photoreceptor tram 5 is formed by the toner T.
Therefore, the same toner T is electrostatically attracted to the latent image.

FIG. 2 is an explanatory diagram of the main parts of the same embodiment, and as described above, 1 is a developing sleeve, 2 is a supply roller, E is an electret, and T is a toner.

First, the toner reservoir T at the bottom. The toner T electrostatically adheres to the elect 1 film 88 layer of opposite polarity, and is conveyed toward the developing sleeve 1 as the supply roller 2 rotates.

In this case, the present invention is characterized in that only charged toner T is transported, and uncharged toner T is not transported.

As the developing sleeve 1 rotates, the toner T electrostatically adheres to the electrified layer 88 of the supply roller 2 and is rotated and supplied.
At the contact portion, the sheets are successively stripped off from the supply roller 2 side, transported to the development area 6, electrostatically attracted to the latent image on the photoreceptor tram 5, and developed.

At this time, since the toner T is only charged,
It is electrostatically attracted to the latent image and does not scatter to the surroundings.

Further, since there is no uncharged toner T, the toner T does not adhere to the portion of the photoreceptor tram 5 where there is no latent image, and so-called fogging phenomenon does not occur.

As described above with respect to the embodiments, the present invention has a sub-supply roller 2 that supplies toner T to the main developing sleeve 1, and an elect 1 frame having a polarity opposite to that of the toner T on the outer periphery of the supply roller 2. This developing device is equipped with 88 layers, and utilizes the electrostatic properties of electret to transport only charged toner to the development area, and prevents unnecessary uncharged toner from being transported, thereby preventing contamination of the surrounding area due to toner scattering. Also, it is possible to prevent image stains due to so-called fog.

[Effects of the Invention] As described above, according to the present invention, since the supply roller is equipped with the electret 1i5 having the opposite polarity to the toner, only the charged toner is supplied to the developing sleeve, and uncharged toner is not supplied, so that the developing area is In the developing process, toner scattering and fogging can be suppressed, and surrounding contamination and image staining can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of essential parts of the same embodiment, and FIG. 3 is an explanatory diagram of a conventional example. 1--Developing sleeve, 2--Supply roller, T...Toner E...Electret.

Claims (1)

[Claims] A developing device that has an electret layer with the opposite polarity to the toner on the supply roller that supplies toner to the developing sleeve.