JPS6235098Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses an insulating magnetic toner to form a magnetic brush on a developing sleeve, and develops an electrostatic latent image formed on a photoreceptor having a photosensitive layer on a conductive support member. The present invention relates to a photographic developing device.

A developing method using an insulating magnetic toner is described in, for example, Japanese Patent Laid-Open No. 51-26046. A developing device using this developing method has various advantages not found before, such as a simple structure, easy maintenance, and the ability to obtain clear transferred images on plain paper. However, while it has these advantages, it also has a drawback that should be improved: the toner becomes charged more than necessary for development due to frictional charging, which causes fogging, that is, scumming. .

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic apparatus which is an improvement over the above-mentioned apparatus and which does not cause fogging. The basic structure of the present invention for achieving this purpose is that a developing sleeve and a member provided around the developing sleeve so as to be in contact with a magnetic brush on the developing sleeve have polarity generated by frictional electrification of toner. This is characterized in that DC voltages of opposite polarity are applied so that they have the same potential.

The present invention will be explained in detail below with reference to the drawings.

The figure is a configuration diagram showing an embodiment of an electrophotographic developing device according to the present invention. In the figure, 1 is a hopper that drops insulating magnetic toner 2 as a developer;
3 is an electrically conductive and non-magnetic developing sleeve; 4 is a rear wall of the developing device forming a toner reservoir together with the sleeve 3; The insulating magnetic toner 2 is made of toner particles that do not contain carrier particles, and is ferromagnetic and has insulating properties. In particular, resistivity 10 ¹⁴
It is preferable that the material has high insulation properties of Ωcm or more. Reference numeral 5 denotes a group of stationary magnets with different polarity alternately arranged, and is arranged inside the sleeve 3. Reference numeral 6 denotes a spike regulating plate attached to the lower end of the rear wall 4 of the developing device, and the tip of this plate and the sleeve 3 form a gap 7 between the spike cutting plates. 8 is a conductive frictional charging member. This frictional charging member 8 is disposed after the spike control plate 6 . 9 is a conductive support member such as an aluminum drum;
A photosensitive layer for electrophotography such as zinc oxide or an organic semiconductor is provided on this layer to constitute a photoreceptor 10 (the conductive support member 9 and a part of the photoreceptor 10 are shown in the figure). And photoreceptor 1
0 and the sleeve 3 constitutes a developing gap 11. Note that the conductive support member 9 is grounded.
Reference numeral 12 denotes a DC voltage source with a variable output voltage, and the output voltage is applied to the sleeve 3, the spike control plate 6, and the frictional charging member 8.

Next, the operation of the device of the present invention constructed as described above will be explained. First, the toner 2 is dropped from the hopper 1 into a toner reservoir formed by the sleeve 3 and the rear wall 4 of the developing device, and is stored in the developing device. Here, when the sleeve 3 is rotated clockwise, the toner 2 moves in the direction of rotation of the sleeve 3 through the cutting plate gap 7, and is guided onto the sleeve 3 as a thin layer corresponding to the cutting plate gap 7. Furthermore, the toner 2 is transferred to the magnet group 5.
It moves while maintaining its standing state due to the action of
reach. The toner 2 that has become fluffy due to the action of the main magnet 5a in the development gap 11 is
It contacts the photoreceptor 10, and the electrostatic latent image is developed. Note that a known method is used to create the electrostatic latent image.

In the apparatus of this embodiment having this configuration, the charge held by the toner 2 due to frictional charging can be suppressed within a certain range by adjusting the output voltage of the DC voltage source 12. Therefore, fogging due to excessive charging of the toner 2 does not occur.

Toner having an excessive charge that causes fogging has a charge polarity opposite to that of the electrostatic latent image. In this embodiment, this excess charge is controlled by applying a voltage to the developing sleeve, spike control plate, or frictional charging member so that the polarity is the same as that of the electrostatic latent image, thereby preventing fogging. could be prevented. The applied voltage is
When the photoreceptor was of the zinc oxide-resin binder dispersion type, excellent antifogging effects were exhibited at about -20 to -300V.

Although the above embodiment has a configuration in which the output voltage from the DC voltage source 12 is applied to the sleeve 3, the spike control plate 6, and the friction charging plate 8, the present invention is not limited to this. . Further, the frictional charging member 8 is not necessarily required.

As explained above, in the present invention, a DC voltage of opposite polarity to that generated by frictional electrification of the toner is applied to the sleeve and the surrounding members so that they have the same potential, so that the toner is frictionally charged. Since the amount of charge obtained is controlled, clear images without fog can be obtained.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an embodiment of a developing device according to the present invention. DESCRIPTION OF SYMBOLS 1... Hopper, 2... Toner, 3... Sleeve, 5... Magnet group, 6... Ear standing regulation plate, 8... Frictional charging member, 9... Conductive support member, 10...
Photoreceptor, 12...DC voltage source.

Claims (1)

[Scope of utility model registration request] In an electrophotographic developing device that uses insulating magnetic toner to develop an electrostatic latent image formed on a photoreceptor having a photosensitive layer on a conductive support member by forming a magnetic brush on a developing sleeve, the developing sleeve and a member provided around the developing sleeve so as to be in contact with the magnetic brush on the developing sleeve, applying a DC voltage of opposite polarity to that generated by the frictional charging of the toner so that the same potential is applied. An electrophotographic developing device characterized by: