JPS6033577A - Developing method - Google Patents

Abstract

PURPOSE:To improve the sharpness of an image by establishing an oscillation electric field in a development area which holds a surface gap for a contactless jumping phenomenon using a composite developer, varying the oscillation waveform of the oscillation electric field, and adjusting developing preformance. CONSTITUTION:An oscillation power source 10 impresses a voltage containing an oscillation component to a developing sleeve 2 through a protection resistance 11 to establish the oscillation electric field in the development area A. This oscillation power source 10 outputs voltages with different oscillation waveforms which vary in one or two of the amplitude of an AC and an impulsive voltage, bias of a DC voltage, selection time of time selection waveform conversion, frequency, etc. Thus, the oscillation waveform of the oscillation electric field produced in the development area A is varied to adjust recording image density, i.e. development density. Consequently, the development density is adjusted easily by the relatively simple device to reproduce a recording image with good gradations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an electrostatic image developing method for an electrostatic recording device such as an electrophotographic copying device, and particularly to an image carrier on which an electrostatic image is formed;
A developer transporting carrier that supports and transports a layer of a composite developer such as a two-component developer containing a chargeable component is placed facing the developer while maintaining a surface gap equal to or greater than the thickness of the developer layer. ,
The present invention relates to a developing method for developing the electrostatic image.

[Prior art]

Generally, in a composite developer, toner particles do not contain magnetic material,
It is easy to control charging due to friction with magnetic carrier particles, and therefore it is easy to be attracted according to the electrostatic image potential of the image carrier, so it is preferable to leave a gap between the image carrier and the developer transport carrier. In the so-called non-contact jumping developing method described above, in which toner particles are caused to fly from the developer transport carrier side to the image carrier side, the image carrier When potential fluctuations occur in the electrostatic image formed on the surface of the image, it is necessary to adjust the development density to a constant level by exposing the electrostatic image to a uniformly charged image carrier surface. Conventionally, it has been common to adjust the aperture of the exposure optical system to be formed, or to adjust the intensity of the light source. Such a method for adjusting the development density has problems in that the exposure optical system is complicated and the cost is high, and the light source is limited to a heat-generating light source such as a halogen lamp.

On the other hand, in non-contact jumping development methods that use a one-component developer mainly consisting of toner particles, the toner particles generally contain a magnetic material, and it is difficult to control charging due to friction between the toner particles. Since a control electric field is required and it is easy to be controlled by the electric field, an oscillating electric field is formed in the developing area between the image carrier and the developer transport carrier in order to solve the problem of the method of adjusting the developer density as described above. In this way, the developed density is adjusted by changing the amplitude and bias of the oscillating electric field.
It is known from the publication No.

[Purpose of the invention]

The present invention aims to realize development performance, particularly adjustment of development density, in a non-contact jumping development method using a composite developer, and was made in order to solve the problems in the conventional development density adjustment method described above. Therefore, the method of adjusting the developing density by changing the amplitude and bias of the oscillating electric field in the developing method using the -component developer has an excellent effect even in the developing method using the composite developer, which has a completely different toner charging theory and development theory. This was done after discovering what it would bring. That is, as mentioned earlier, in the case of a -component developer, the toner particles are not sufficiently charged and are easily controlled by a control electric field, but in the case of a composite brightener, the toner particles are not sufficiently charged. Since toner particles are easily charged and adsorbed depending on the electrostatic image potential, using a controlled electric field as in the case of a -component developer risks impairing the development performance of the toner particles. Conventionally, in non-contact jumping development methods using two-component developers, control electric fields have not been used as in the case of -component developers. The present invention has been achieved by overcoming such preconceptions or blind spots of those skilled in the art.

[Structure of the invention]

The present invention provides an image bearing member on which an electrostatic image is formed and a developer transporting carrier that supports and transports a layer of a composite developer containing a chargeable component. In the developing method of developing the electrostatic images while maintaining the surface gap and facing each other, an oscillating electric field is formed in the developing area where the surface gap is maintained, and the oscillating waveform of the oscillating electric field is made variable, thereby improving the developing performance. With this feature, the development density can be effectively adjusted without impairing the development performance of the toner particles of the composite developer, and moreover, it is possible to adjust the development density more easily than when using a -component developer. This achieves the objective of obtaining images with excellent clarity.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated examples.

(5) Figure 1 is a schematic configuration diagram showing an example of a developing device implementing the method of the present invention, and Figure 2 shows the relationship between electrostatic image density and recorded image density when the amplitude of the oscillating electric field is changed. This is a graph showing.

In FIG. 1, reference numeral 1 rotates in the direction of the arrow, and a known charging and exposure device (not shown) or an electrostatic latent image forming device using a multi-stylus electrode or an ion control electrode is attached to the surface.
1 is a drum-shaped image carrier having an electrophotographic photoreceptor layer or a dielectric layer on which an electrostatic image is formed; 2 is a developing sleeve made of a non-magnetic material such as aluminum; The developing sleeve 2 and the magnet body 3 are provided with a magnetic body having a plurality of N and S magnetic poles on its surface in the circumferential direction.
and constitute a developer transport carrier. The developing sleeve 2 and the magnet body 3 are rotatable relative to each other, and the figure shows that the developing sleeve 2 rotates to the left and the magnet body 3 rotates to the right. In addition, the N and S magnetic poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 1500 Gauss,
The magnetic force causes a layer of developer material consisting of frictionally chargeable (6) toner particles and magnetic carrier particles to adhere to the surface of the developing sleeve 2, thereby forming a so-called magnetic brush.

The toner particles in the developer have a weight average particle diameter of 3 to 30 μm,
Preferably, the magnetic carrier particles have a weight average particle diameter of 5 to 50 μm, and more preferably, the magnetic carrier particles are formed by dispersing magnetic fine particles in an insulating resin. The magnetic brush moves in the same direction as the rotation of the developing sleeve 2 due to the above-mentioned rotation of the developing sleeve 2 and the magnet body 3, and the magnetic brush moves in the same direction as the rotation of the developing sleeve 2.
04 is a layer thickness regulation blade made of a magnetic or non-magnetic material that regulates the height and amount of the magnetic brush on the surface of the development sleeve 2. The surface gap between the image carrier 1 and the developing sleeve 2 is equal to or larger than the regulated layer thickness of the magnetic brush, that is, the magnetic brush does not rub the surface of the image carrier 1, and toner particles fly from the magnetic brush and form an image. The distance is set at an appropriate distance for adhesion to the electrostatic image on the carrier 1, so-called non-contact jumping development. The surface gap between the image carrier 1 and the developing sleeve 2 is set to 0.3 to 1.5.
The magnetic brush layer 1 is 0.1 to 0.5 mm thick, and the magnetic brush and the surface of the image carrier 1 are 0.1 to 1 mr thick.
It is preferable to set the distance so that a gap of n is generated.

5 is a cleaning blade that removes the magnetic brush that has passed through the developing area 5 from above the developing sleeve 2; 6 is a developer reservoir; 7 is a cleaning blade that stirs the developer reservoir in the developer reservoir 6 to mix toner particles and carrier particles; 8 a toner hopper for replenishing the toner particles T; 9 a toner supply roller having four parts on the surface of the reservoir that drops the toner particles T into the developer reservoir 6; 10 a retention resistor 11; This is a vibrating power source that applies a voltage having a vibrating component to the developing sleeve 2 through the developing sleeve 2 to form a vibrating electric field in the developing area A. Vibration power supply 10
is a power source capable of outputting a voltage with a different oscillating waveform by changing one or more of the amplitude of AC voltage or pulsed voltage, bias by DC voltage component, selected time or frequency by time-selective waveform conversion, etc., Accordingly, by changing the oscillating waveform of the oscillating electric field formed in the developing area A, the recorded image density, that is, the developed density can be adjusted, as shown in an example in FIG.

FIG. 2 shows that the vibration power source 10 of FIG.
It outputs an oscillating voltage obtained by superimposing an alternating current voltage of Hz and a direct current bias voltage of -150 cm. The surface velocity in the direction of the arrow is 120''/The gap between the BeCs image carrier 1 and the developing sleeve 2, that is, the gap between the developing area A, is 700 μm1 Outer diameter 3Q+
The rotation speed of the u+ developing sleeve 2 in the arrow direction is 65r, 9
3 m1, the gap between the layer thickness regulating blade 4 made of non-magnetic material and the developing sleeve 2 is 300 μm1, the rotation speed in the direction of the arrow of the magnet 3 having 8 equally spaced N and S magnetic poles with a magnetic flux density of 900 Gauss is 70 Or, p, m, an insulating magnetic carrier with a weight average particle size of about 30 μm and a resistivity of about 1×1014 Ω, which contains magnetic powder dispersed in a resin, and an insulating non-magnetic toner with a weight average particle size of 14 μm in a developer. The results of the image development (9) are shown under the condition that the layer thickness of the magnetic brush formed on the developing sleeve 2 is approximately 200 μm by using a two-component developer (developer for EP 310 made by Minolta). There are 1,7. The recorded image density on the vertical axis is determined by transferring the developed toner image to a recording paper using a transfer device (not shown in FIG. 1), and fixing the transferred toner image by a fixing device. The image density corresponds to the development density, and the VaO of each density curve is the effective value of the output AC voltage component of the oscillating power supply 10, and the background part of the electrostatic image, that is, the non-image part potential is -50V. there were.

As is clear from Fig. 2, even if the electrostatic image potential fluctuates by more than 100 V, by changing the amplitude of the oscillating electric field formed in the developing area, the developed density can be adjusted so that the recorded image density remains constant. can be adjusted.

As for the oscillating electric field, the effective value of the AC voltage component is 200 to 5.
It is preferable to apply an oscillating voltage of 000 V to produce an electric field strength of 300 to 3000 V/lnm in effective value.

The present invention is not limited to the example of changing the amplitude in FIG. 2, but may also be done by changing the level of the 1u current bias voltage superimposed on the AC voltage component (10) together with or without changing the amplitude. The AC voltage may be a pulsed voltage, the vibration waveform may be changed by time selection conversion, or the frequency may be changed.

When changing the frequency, since the developed density and the recorded image density will decrease as the frequency increases when the frequency exceeds 2 kHz, the developed density may be adjusted by changing the frequency within that range. The preferred frequency range is 0.3-5 kHz.

〔Effect of the invention〕

According to the present invention, even in a developing method using a composite developer whose charge can be easily controlled compared to a -component developer, the developer density can be easily adjusted using a relatively simple device, resulting in excellent gradation. This is an extremely good result in that the recorded image can be reproduced, and the density of the recorded image can be adjusted with better gradation reproducibility than when using a -component developer. is obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a developing apparatus for carrying out the method of the present invention, and FIG. 2 is a graph showing the relationship between electrostatic image potential and recorded image density when the amplitude of the oscillating electric field is changed. 1... Image carrier, 2... Developing sleeve, 3...
Magnet body, 4... Layer thickness regulating blade, 5... Cleaning blade, 6... Developer reservoir, 7... Stirring screw, 8...
... Toner hopper, 9 ... Toner supply roller, 10
...Vibration power supply, 11...Protection resistor. Patent applicant Konishiroku Photo Industry Co., Ltd. Figure 1 No. ? figure

Claims (1)

[Scope of Claims] (1) An image bearing member on which an electrostatic image is formed and a developer transport carrier that supports and transports a layer of a composite developer containing a chargeable component. In the developing method of developing the electrostatic image by maintaining a surface gap equal to or greater than the thickness of the layers and making them face each other, an oscillating electric field is formed in a developing area where the surface gap is maintained, and the oscillating waveform of the oscillating electric field is variable. A developing method characterized in that developing performance is adjusted by adjusting. (2) The developing method according to claim 1, wherein the oscillating electric field is an alternating electric field. (6) Claim 1 or 2, wherein the change in the oscillating waveform of the oscillating electric field is caused by changing any one of the amplitude, bias, selected time of time-selective waveform conversion, or frequency. development method.