JPH02124586A - Developing device - Google Patents

Abstract

PURPOSE:To stabilize developing characteristic by switching two or more kinds of potentials out of plural kinds of potentials by a potential switching means while keeping a potential difference in plural modes. CONSTITUTION:The developing bias potential (p) is switched in a developing mode and a non-developing mode by a mode changeover switch 14, so that toner is allowed not to adhere to the surface of a photosensitive body 1 in the non-developing mode. The supply potential (q) impressed on a supplying roll 4, the regulation potential (r) impressed on a toner layer regulating roll 5 and the separation potential (s) impressed on a toner separating roll 6 are switched while keeping the respective potential differences between the developing bias potential (p) and these potentials. Thus, the developing characteristic is prevented from being unstable by switching the potentials.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a developing device used in copying machines, printers, etc. [Prior Art] Conventionally, in a developing device, multiple types of potentials including a developing bias potential are applied. There are bias voltages applied to different locations, and there are special ones in which the latent image on the latent image carrier is reversely developed during development in an electrophotographic device, and the polarity of the developing bias potential is changed between developing and non-developing. [Problem to be Solved by the Invention] Known from Publication No. 62-23310 [Problem to be Solved by the Invention] When multiple types of potentials including a developing bias potential are applied to different locations in a developing device, each potential difference between the multiple types of potentials Development 1 hener (
The amount of charge (=toner deposited on the latent image carrier) and the amount of developing toner are determined. On the other hand, if the potential difference among the plurality of potentials changes, the amount of charge of the developer 1-ner, the amount of the developer 1-ner, etc. will change, and the development characteristics will change. Conventionally, when changing the developing bias potential using a moat, only the developing bias potential is changed and the other potentials are not changed, so the amount of charge of the developer 1 hener, the amount of the developer 1-ner, etc. changes, and this change occurs instantaneously. Sometimes it doesn't happen. In other words, when the potential is switched, the rotating parts installed in the developing device partially retain their previous state, so when the rotating parts rotate one cycle, all the parts remain in the state after the potential is switched. mode 1 after switching the potential.
The amount of charge of the developing toner, the amount of the developing toner, etc. Moreover, if the electrical properties of the toner layer, the developing roller surface layer, etc. have a time constant, the change in electrical properties due to potential switching is gradual, and it takes time for the state to stabilize after potential switching. Garu.

Therefore, even if the mode is switched, the development characteristics such as the amount of charge of the developer 1-toner and the amount of developer toner are not stabilized immediately. For this reason, the waiting time, in which the developing operation must be performed after waiting for the developing characteristics to stabilize, is wasted. Moreover, when the developing characteristics are unstable, problems such as toner adhering to non-image areas of the latent image carrier may occur. If the development operation is performed without waiting for the development characteristics to become stable, the image will become unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device which can improve the above-mentioned drawbacks and prevent development characteristics from becoming unstable due to potential switching.

[Means to solve the problem]

In order to achieve the second object, the present invention provides a developing device in which a plurality of types of potentials are respectively applied to predetermined locations, in which at least two of the plurality of potentials are applied while maintaining a potential difference. It is equipped with potential switching means for switching by a plurality of modes 1 to 1.

[For production]

The potential switching means switches at least two or more types of potentials among the plurality of types of potentials while maintaining a potential difference in a plurality of modes.

〔Example〕

FIG. 1 shows an embodiment of the invention.

This embodiment is an electrophotographic apparatus consisting of a laser printer, in which an electrostatic latent image on a latent image carrier 1 made of a photoreceptor is reversely developed, and the photoreceptor 1 is a negatively charged organic photoreceptor. There is. The photoconductor 1 is rotationally driven in the direction of arrow A by a motor and charged to a negative potential by a charger, and then irradiated with laser light by a laser irradiation unit to form an electrostatic latent image. is developed by the developing device 2 of this embodiment and transferred onto the transfer paper from the paper feed section by the transfer device.

In the developing device 2, the developing roller 3 is a core metal layer.

Conductive elastic layer, 50μ thick Lumicron 601 manufactured by Asahi Glass
It has a four-layer structure, including an insulating layer consisting of an insulating layer, and a surface layer consisting of Lumicron 601 with a thickness of 30 μm in which carbon is dispersed.The supply roller 4 is made of foamed polyurethane which has been subjected to conductive treatment around a core metal. The 1 to 1 layer regulating roller 5 and the toner peeling roller 6 are made of stainless steel whose surface has been hardened, and the 1 to 1 layer 7 is negatively charged. The rollers 3 to 6, the toner 7, and the agitator 8 are disposed in the developer container 9, and the rollers 3 to 6 and the agitator 8 are each driven to rotate in the direction of the arrow B-r'' shown in the figure by a drive mechanism.

The toner 7 in the developer container 9 is stirred by an agitator 8, and the supply roller 4 supplies the toner 7 in the developer container 9 to the developer roller 3 while rotating in contact with the developer roller 3. The i-toner layer regulating roller 5 rotates in contact with the developing roller 3 and regulates the amount of 1-toner on the developing roller 3. The developing roller 3 supplies toner to the photoreceptor 1 to develop the electrostatic latent image, and the toner peeling roller 6 peels off the toner from the developing roller 3'' after it passes the developing position and returns it into the developing container 9.

In this embodiment, the developing mode and the non-developing mode 1 are switched, and the non-developing mode 1 is switched, for example, before the transfer paper is conveyed from the paper feeding section to the photoreceptor 1. In this non-development mode, the photoreceptor 1 is not charged, and is charged only in the development mode. In the development mode, the photoreceptor 1 is charged to -850V by the charger, and the voltage becomes about -100V by laser irradiation by the laser irradiation section, and this portion is developed by the adhesion of toner by the development device 2 in reverse development.

In the non-development mode in which the photoreceptor 1 is not charged, the surface of the photoreceptor 1 is charged to about O to -100V. Therefore, in the non-developing mode, if the developing bias potential A applied to the developing roller 3 is the same as that in the developing mode, toner will adhere to the entire surface of the photoreceptor 1. Therefore, the developing bias potential A is switched between a developing mode and a non-developing mode to prevent toner from adhering to the surface of the photoreceptor 1 in the non-developing mode.
In addition, the supply weight position applied to the supply roller 4, the regulating potential C applied to the first hender layer regulating roller 5, and the peeling potential C applied to the toner peeling roller 6 are also determined by the potential difference between this and the developing bias potential A. can be switched while maintaining the FIG. 3 shows the potentials I, H and 2 at each mode 1-, and G in the figure is the surface potential of the photoreceptor 1. As can be seen from this figure, in the non-development mode, the development A bias potential is +450V, the supply weight position is +150V, the regulation potential C is +150V, and the stripping potential 2 is +750V. 400■, the supply weight position is -700V, the regulation potential (2) is -700V, and the peeling potential (2) is 1100V.

FIG. 1 shows a power supply circuit for applying the above-mentioned potential illumination in this embodiment.

The power pack 11 consists of a variable DC power supply 12.11 and a mote changeover switch 14, and an i+T variable DC power supply 12,
13 output constant voltages of -1150V and +B50V, respectively.

The output voltage of this variable DC power source 12, 13 can be adjusted by an adjustment mechanism. In the development mode, the switch 11 has the movable contact A connected to the fixed contact 1, and the movable contact B connected to the fixed contact 1.
The output voltage is applied through the switch 14 to the series circuit of the bidirectional constant voltage elements 1.5, 16.17 and the resistor 18. The bidirectional constant voltage element 15 is one that generates a constant voltage of +50V, and the bidirectional constant voltage elements 16 and 17 are 3
A device that generates a constant voltage of 00 V is used.

Therefore, a voltage of 1100 V is obtained at the connection point between the bidirectional constant voltage element J7 and the resistor 18, and this voltage is applied to the 1 Henner peeling roller 6 as the peeling potential 2.

A voltage of -400 V is obtained at the connection point of the bidirectional constant voltage elements 16 and 17, and this voltage is applied to the developing roller 3 as a developing bias potential A. Bidirectional constant voltage element 1.5
, 1.6, a voltage of -700V is obtained, and this voltage is applied to the supply rollers 4.1 to 4.1 as the regulation potential at the supply heavy position.
N is applied to the regulating roller 5.

In the non-developing mode, the switch 14 has the movable contact piece A connected to the fixed contact point S and the movable contact piece B connected to the fixed contact point C, so that the output voltage of the variable DC power supply 13 is passed through the switch 14 to the bidirectional constant voltage element 15, 16.17 and resistor J8. Therefore, a voltage of +750V obtained from the connection point of the bidirectional constant voltage element 17 and the resistor 18 is applied to the toner peeling roller 6 as the peeling potential 2,
+ obtained from the connection point of bidirectional constant voltage elements 16 and 17
A voltage of 450 V is applied to the developing roller 3 as the developing bias potential A, and a voltage of +150 V obtained from the bidirectional constant voltage elements 16 and 17 is applied to the supply roller 4° and the toner layer regulating roller 5 as the regulating potential C. applied. As a result, the development bias potential (a), the supply weight position, and the regulation potential (c).

Each potential difference with peeling potential 2 is maintained at 300■,
The supply weight position, the potential difference between the regulation potential C and the peeling potential II are each maintained at 600V. For this reason.

Each potential difference between the two potentials that affects the development characteristics is
Even when .about. is switched, it remains constant, and the internal conditions of the developing device always remain unchanged, so that development characteristics such as the amount of charge of the developer 1-ner and the amount of developing toner do not change. The only things that change in each mode are the conditions of the developing device 2 and the outside, especially the photoreceptor 1. Therefore, the development characteristics are stabilized immediately after the mode is switched, and there is no need to waste time waiting until the development characteristics become stable after switching the mode or to avoid problems caused by unstable development characteristics, as in the prior art.

Note that the present invention is not limited to the above-mentioned embodiment in which switching is performed between developing mode 1- and non-developing mode 1-, and the same applies when switching between multiple modes for image adjustment, for example. It can be applied to

〔Effect of the invention〕

As described above, according to the present invention, in a developing device in which a plurality of types of potentials are respectively applied to predetermined locations, a potential difference between at least two of the plurality of potentials is maintained. Since it is equipped with a potential switching means that switches between multiple modes, it is possible to prevent development characteristics from becoming unstable due to potential switching, and it saves the time required to wait for development characteristics to stabilize after mode switching as in the conventional method. Eliminates waste and problems due to unstable development characteristics.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a power supply circuit according to an embodiment of the present invention, FIG. 2 is a sectional view showing the same embodiment, and FIG. 3 is a timing chart 1 to 1 showing applied voltages in the same embodiment. 12.13... Variable DC power supply, 14... Moto changeover switch, 15.16.17... Bidirectional constant voltage element, 18... Resistor. \ingredient

Claims (1)

[Claims] A developing device in which a plurality of types of potentials are respectively applied to predetermined locations, comprising a potential switching means for switching at least two or more types of potentials among the plurality of potentials according to a plurality of modes while maintaining a potential difference. A developing device characterized by: