JPS60200272A - Developing device - Google Patents

Abstract

PURPOSE:To decrease generation of fogging and to form a sharper recording image by adjusting the higher harmonic component of the oscillating electric field in a developing area thereby adjusting the developing characteristic. CONSTITUTION:The developing characteristic in a developing region A changes with a change in a time constant when the higher harmonic component of the socillating electric field in the region A is adjusted by changing over the time constant of a high frequency adjusting circuit 11 consisting of an R-C integration circuit. The specified density of the recording image is maintained even if the potential of the electrostatic latent image changes. There is thus no need for changing the amplitude, frequency or DC component of the oscillating component and therefore the power source circuit is made simpler and the possibility of fogging is decreased. The sharp recorded image having an excellent gradation characteristic is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an electrostatic image developing device in an electrostatic recording device such as an electrophotographic copying device, and more particularly, the present invention relates to an electrostatic image developing device for an electrostatic recording device such as an electrophotographic copying device, and in particular, the present invention relates to a developing device for an electrostatic image in an electrostatic recording device such as an electrophotographic copying device. The present invention relates to a developing device having a power supply device that generates an alternating current electric field in a developing area to which is supplied an alternating current electric field.

[Prior art]

Conventionally, the above-mentioned developing device is known.

A developing method in which the developing density was adjusted by changing the amplitude of the alternating current electric field or the voltage value of the direct current component was disclosed in Japanese Patent Laid-Open No. 5
It is known from the publication No. 5-118048. moreover,
A developing method in which the developing density is adjusted by changing the frequency of the alternating current electric field is also known from Japanese Patent Application Laid-Open No. 55-133058. In this way, the method of adjusting the developed density by changing the electric field strength and frequency of the oscillating electric field is cheaper for the recording device than the method of changing the aperture of the optical system, and is more adaptable than the method of changing the light source intensity. It has the advantage of being spacious, but
However, the method of changing the strength of the oscillating electric field tends to cause fogging, and the method of changing the frequency has a narrow range of change in developing density, so in any case, it is possible to produce a clear record with sufficient gradation. It is difficult to adjust the development density to obtain an image.
In addition, in order to change the strength of the oscillating electric field in response to changes in the electrostatic image potential and background potential, two types of changing voltages are required, which makes the power supply complex, and it is difficult to convert the frequency. Furthermore, there is also the problem that the power supply device is complicated.〇 [Object of the Invention] The present invention aims to increase the developing density so that a clear recorded image with sufficient gradation can be obtained by applying an oscillating electric field to the developing area. [Structure of the Invention] The present invention provides a developing device that can be adjusted and has a power supply device configured relatively easily. A developing device having a power supply device that generates an oscillating electric field in a developing region, wherein the power supply device is provided with means for adjusting harmonic components of the oscillating electric field; 0 [Example] that achieves the above object The present invention will be described below with reference to the drawings.

FIG. 1 is a partial configuration diagram of a recording device showing an example of the developing device of the present invention, FIG. 2 is a circuit diagram showing an example of a power supply device, and FIG. 3 is a *
Figures 4 and 5 are graphs showing examples of the output waveform of the periodic voltage generation circuit of the m device, Figures 4 and 5 are graphs showing examples of the output waveform of the integrating circuit of the power supply unit, and Figure 6 is a graph showing examples of the output waveform of the integrating circuit of the power supply device. 7 is a graph showing changes in development characteristics when changing the waveform of the oscillating electric field in the development area.

In FIG. 1, numeral 1 rotates in the direction of the arrow, and an electrostatic latent image is formed on its surface by 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. 2 is a developing sleeve made of a non-magnetic material such as aluminum, and 3 is provided inside the developing sleeve 2 and has a plurality of N, S on its surface. @A magnet body with poles in the circumferential direction, and this developing sleeve 2 and magnet body 3
The developing sleeve 2 and the magnet body 3 are relatively rotatable, and in the figure, the developing sleeve 2 rotates to the left and the magnet body 3 rotates to the right. It is shown that. 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,
Due to its magnetic force.

A layer of developer consisting of toner particles and carrier particles is adhered to the surface of the developing sleeve 2 to form a so-called magnetic brush.This magnetic brush consists of the developing sleeve 2 and the magnet 3.
04 moves in the same direction as the 20 rotations of the developing sleeve and is conveyed to the developing area A by the above rotation of the developing sleeve 2. A layer 04 made of a magnetic material or a non-magnetic material that regulates the height and amount of the magnetic brush on the surface of the developing sleeve 2 is a layer thickness regulator. A cleaning blade 5 removes the magnetic brush that has passed through the development area A from the developing sleeve 2, a developer reservoir 6, and a blade 7 that stirs the developer reservoir in the developer reservoir 6 to mix toner particles and carrier particles. 8 is a toner hopper for replenishing the toner particles T; 9 is a toner supply roller having four parts on the surface for dropping the toner particles into the developer reservoir 6; 1
0 is a periodic voltage generation circuit that generates a periodic waveform voltage as shown in FIG. 3, and 11 is a harmonic adjustment circuit that converts the output waveform of the periodic voltage generation circuit 10 as shown in FIGS. 4 and 5. , 12 is an amplification/superposition circuit that amplifies the output of the harmonic adjustment circuit 11 and further superimposes a DC bias voltage. Create an oscillating electric field at A.

Here, a circuit as shown in FIG. 2 is used for the harmonic adjustment circuit 11 and the amplification/superposition circuit 12. And R-0
If the time constant τ of the harmonic adjustment circuit 110 consisting of an integrating circuit is made small, the rectangular wave output as shown in FIG. 3 of the synchronous voltage generation circuit 10 is transformed as shown in FIG. If the time constant τ is increased, the transformation is transformed as shown in FIG. The development characteristics in the development area A change as shown in FIG. 6 as the time constant τ changes.

FIG. 6 shows that the electrostatic latent image forming layer of the image carrier 1 is a layer consisting of a charge generation layer and a charge transport layer made of an organic photoconductor OPO, and its surface velocity in the direction of the arrow is 1201+31/sea.
, the gap between the image carrier 1 and the developing sleeve 2, that is, the gap between the developing area A, is 750 μm, and the developing sleeve 2 has an outer diameter of 30 mm.
The rotation speed in the direction of the arrow is 65 rpm.

Layer thickness regulating blade 4 and developing sleeve 2 made of non-magnetic material
The rotation speed of the magnet 3 in the direction of the arrow is 70 Orpm, which has 8 N and S magnetic poles with a gap of 350 μm and a magnetic flux density of 900 Gauss at equal intervals. Resistivity containing dispersed powder is approximately 1x
Insulating magnetic carrier of 1014Ω and weight average particle size of 1
A two-component developer consisting of 3 μm insulating non-magnetic toner (
The graph shows the recorded image density curves obtained by developing electrostatic latent images of various potentials under the conditions of using a developer for EP310 (manufactured by Minolta). This is the result of applying a voltage containing an oscillating component with a period T of o and 5 m5 ec by changing only the time constant of the harmonic adjustment circuit 11 using the power supply circuit. In addition, the development in this case is
A magnetic brush formed on the developing sleeve 2 is attached to the image carrier 1.
A so-called non-contact jumping development method is used in which toner particles fly from a magnetic brush onto the surface of the image carrier 10 without rubbing the surface of the image carrier 10. Further, the recorded image density is the image density of the recording paper obtained by transferring the developed toner image onto the recording paper by a transfer device (not shown) and fixing the transferred toner image by a fixing device.

As is clear from the results shown in FIG. 6, by simply changing the time constant τ of the harmonic adjustment circuit 110, the electrostatic latent image potential can be increased by 300
It is possible to adjust the recorded image density, that is, the developed density, to be constant even if the density changes by about It can be controlled and there is no need to change the amplitude or frequency of the vibration component or the DC component, which simplifies the power supply circuit and
Clear recorded images with excellent gradation can be obtained with less fogging.

The present invention is not limited to the above-described example, and the output waveform of the periodic voltage generation circuit IO may be a triangular wave, a sawtooth wave, or another periodic waveform, and the harmonic adjustment circuit 11 may be
The present invention is not limited to a 0-integration circuit, and other elements may be used. The present invention further provides a wire or grid-shaped control electrode that does not prevent the toner from flying from the magnetic brush to the electrostatic image between the image carrier 1 and the developing sleeve 2, and vibrates the control electrode. An oscillating electric field may be generated in the developing area A by applying a voltage, or a magnetic field may be used.

The present invention can be applied to a device in which a brush rubs the surface of the image carrier 1.Also, a one-component developer can be used in the developing device of the present invention.In fact, a one-component developer can be used. As a result of experiments, it was found that the recorded image density could be adjusted by adjusting the harmonic components of the developing bias, and a good recorded image could be obtained. However, as in the embodiment shown in FIG. 6, the developer is a two-component developer consisting of a carrier (preferably an insulating material with a resistivity of 1013 Ωα or more and a weight average particle size of 40 μm or less) and toner. It is preferable to use a non-contact jumping development method using a developer because toner transfer can be sufficiently controlled by a vibrating electric field and adjustment can be made to obtain a clear recorded image with excellent gradation. In addition, the resistivity of a suitable carrier is Q, 59c for particles.
After placing in a container with a cross-sectional area of m2 and tapping to a thickness of about IW, a load of 1 KF/σ2 was applied on the packed particles, and a voltage of 1000 V/C was applied between the load and the bottom electrode.
This value is obtained by reading the current value when a voltage that generates an electric field No. 11 is applied. If this resistivity is low, when applying an insulating pressure to the developing sleeve 2, charge is injected into the carrier particles, making it easier for the carrier particles to adhere to the image bearing member 1, or causing breakdown of the bias voltage. In addition, the average particle size of the carrier or toner is a value measured using a Coulter Counter manufactured by Coulter or Omnicon Alpha manufactured by Bausch & Lomb. When this happens, it becomes difficult to reproduce delicate images.

It goes without saying that the time constant τ of the harmonic adjustment circuit in the developing device of the present invention can be changed manually, but it can also be done using a computer or the like based on the detection of the electrostatic latent image potential, toner image density, etc. [Effects of the Invention] According to the present invention, as described above, the development characteristics are adjusted by adjusting the harmonic components of the oscillating electric field in the development area. Therefore, there is less risk of fogging, the development density can be adjusted significantly, and clear recorded images with excellent gradation reproducibility can be obtained.Furthermore, the power supply is relatively simple. An excellent effect can be obtained by configuring the structure.

[Brief explanation of the drawing]

FIG. 1 is a partial configuration diagram of a recording device showing an example of the developing device of the present invention, FIG. 2 is a circuit diagram showing an example of a power supply device, and FIG. 3 is a diagram showing an example of an output waveform of a periodic voltage generation circuit of the power supply device. Graphs 4 and 5 are graphs showing examples of the output waveform of the integrating circuit of the power supply device, and Figure 86 shows the development characteristics when the waveform of the oscillating electric field in the developing area is changed by changing the time constant of the integrating circuit. It is a graph showing changes. 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, 1
0... Periodic voltage generation circuit, 11... Harmonic adjustment circuit, 12... Amplification/superposition circuit, 13... Protection resistor. Patent applicant Konishiroku Photo Industry Co., Ltd. Figure 1 β 112 Figure 4 Figure 5 Figure 6 200 400

Claims (2)

[Claims] (1) In a developing device that includes a developer transporting body that transports developer to a developing region and a power supply device that generates an oscillating electric field in the developing region, the power supply device is provided with means for adjusting harmonic components of the oscillating electric field. A developing device characterized by: (2) The developing device according to claim 1, wherein the means for adjusting the harmonic components is an integrating circuit with a variable time constant.