JPH0341486A - One-component developing device - Google Patents

Abstract

PURPOSE:To prevent an elastic roller from being clogged and to maintain functions by setting the blow hole of the elastic roller twice or below of the mean particle size of one-component toner. CONSTITUTION:Like a developing roller 6, the elastic roller 8 is compsed of a conductive, high polymer polyerethane of 50 or below hardness measured by an ASKER C-type hardness meter, brought into contact with the developing roller 6 with a desired nip thickness and rotates in the direction the same as the roller 6. A bias voltage is applied to the roller 8, the one-component, nonmagnetic toner 4 is recovered mechanically and electrically from the surface of the developing roller 6 to delete a mechanical and electrical history from the surface therefrom. The elastic roller has a 3 to 20mum diameter of the blow hole, and is made of a foamed body wherein bubbles of diameters twice of below of the mean particle diameter 10 mum of the toner 4 overlap. Consequently, even if printing is superimposed, the force supporting the toner particles with each other is activated, and clogging of foaming blow holes does not spread to the inside of the roller. Accordingly, the reduction in flexibility and elasticity never occurs, thereby maintaining satisfactory printing quantity.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Conventional technology Problems to be solved by the invention Means for solving the problems (Fig. 1) Working example (a) Description of one example ( Figures 2 and 3) (b)
Description of another embodiment (Fig. 4) (C) Description of another embodiment Effects of the invention [Summary] Regarding a one-component developing device that develops an electrostatic latent image on a latent image carrier using a one-component toner. , prevents clogging of the elastic roller that contacts the toner transport body,
In order to maintain the function, there is a toner conveying body that conveys one-component toner to a latent image bearing member on which an electrostatic latent image is formed; In a monocomponent developing device having an elastic roller for adhering or peeling toner, the pore diameter of the elastic roller is designed to be less than twice the average particle diameter of the monocomponent toner.

[Industrial Application Field] The present invention relates to a one-component developing device that develops an electrostatic latent image on a latent image carrier using a one-component toner.

In image forming devices such as electrophotographic printing devices and electrostatic recording devices, a powder developing device 4 is used to visualize an electrostatic latent image formed on a photosensitive drum or dielectric material that is a latent image carrier. : is used.

In recent years, a single-component developing device using a single-component toner, particularly a non-magnetic single-component toner, which is easy to maintain and can be made compact, has attracted attention as a developing device.

In a one-component developing device, in order to visualize the electrostatic latent image on the latent image carrier, a toner conveying body for supplying one-component toner to the latent image carrier is attached to the latent image carrier. It is installed in pressure contact.

In such a one-component developing device, it is necessary that an appropriately charged one-component toner be uniformly formed on the toner conveying member.

[Conventional technology]

Conventionally, in a single-component developing device, in order to uniformly form appropriately charged single-component toner on a toner conveying member (hereinafter referred to as the developing roller), an elastic roller that comes into contact with the developing roller has been used, as disclosed in Japanese Patent Laid-Open No. 6143767. It is disclosed in the publication number etc.

This elastic roller comes into contact with the developing roller, mechanically and electrically peels off the old toner from the developing roller, and supplies new toner so that toner with a uniform charge exists on the developing roller. , for stripping or feeding toner;
It was made of a sponge-like material with an uneven surface.

[Problem to be solved by the invention]

However, in conventional elastic rollers, the pore size of the sponge is large, which is more than twice the average particle size of the toner, so the mutual supporting effect of the toner particles is small, and the toner enters the foamed pores, gradually increasing as the roller is used. A phenomenon occurred in which the particles penetrated into the center of the roller and caused clogging to progress.

As a result, the elastic roller as a whole loses its flexibility (elasticity), resulting in a problem that the function of collecting and supplying one-component toner is degraded.

When the collection function of monocomponent toner deteriorates, the remaining charged toner is recharged, the specific charge of one toner increases, causing charging failure, and the amount of toner attracted to the electrostatic latent image decreases. Does not cause concentration drop.

Furthermore, if the ability to supply the monocomponent toner deteriorates, the thickness of the toner layer on the developing roller becomes uneven, causing density unevenness.

Therefore, an object of the present invention is to provide a one-component developing device that can prevent clogging of the elastic roller that contacts the toner conveying member and maintain its function.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

The present invention includes a toner conveying body 6 that conveys one-component toner 4 to a latent image carrier 1 on which an electrostatic latent image is formed, a toner conveying body 6 that is in contact with the toner conveying body 6, and a toner conveying body 6 that conveys the one-component toner 4 to a latent image carrier 1 on which an electrostatic latent image is formed. In the monocomponent developing device, the pore diameter of the elastic roller 8 is not more than twice the average particle diameter of the monocomponent toner 4.

[Function] In the present invention, the pore diameter of the elastic roller 8 is
Since we use a foam in which foams with an average particle size of less than twice the average particle size
As shown in B), the mutually supporting force of the toners works sufficiently, and the clogging of the foamed pores by the toner does not proceed inside the roller.

Therefore, clogging of toner stops only in the surface layer, and a decrease in flexibility that impairs its function can be prevented.

This makes it possible to maintain good print quality over the required lifespan.

〔Example〕

(a) Description of one embodiment FIG. 2 is a configuration diagram of an embodiment of the present invention.

In the figure, 1 is the aforementioned latent image carrier, which is composed of an OPC photosensitive drum and is grounded.After being charged to a surface potential of -600V by a pre-charger (not shown), it is exposed by a scanning optical system (not shown). An electrostatic latent image is formed.

2 is a one-component developing device, and in order to visualize an electrostatic latent image by supplying a one-component non-magnetic toner onto a latent image carrier (hereinafter referred to as an OPC photosensitive drum), the following steps are taken. It has a structure.

That is, the developer container 3 stores a one-component non-magnetic toner (polyester toner) 4 having an average particle size of about 10 μm.
The agitator 5 rotates in the direction of the arrow inside the developer container 3 and causes friction with the one-component non-magnetic toner 4, thereby charging the one-component non-magnetic toner 4 to negative polarity (-).

The aforementioned developing roller 6 rotates in the direction of arrow C, conveys the component non-magnetic toner 4 adsorbed to its surface to the contact area with the OPC photosensitive drum 1, and forms an electrostatic latent image on the PC photosensitive drum 1. This is for visualizing images.

The developing roller 6 has, for example, a volume resistance (!104 to 1
0I0Ω・m (optimally 1oSΩ・m), hardness is 10°
~35° (measured with Asker-C hardness tester: optimally) 0
The development bias voltage (-350V) is applied through this central axis, and includes a conductive central axis consisting of a single layer of polymer foam polyurethane (open cell state) and a rigid body (not shown).
is applied.

Further, the developing roller 6 is moved so that the entire developing container 3 is pressed against the OPC photosensitive drum 1 by a biasing means such as a spring (not shown).
By being pressed in the direction indicated by the arrow, it is brought into pressure contact with the OPC photosensitive drum 1 rotating in the direction of the arrow with a predetermined nip width.

Reference numeral 7 denotes a layer thickness regulating bias blade, which is made of aluminum or stainless steel, and is pressed against the developing roller 6 by a biasing means such as a spring (not shown) to keep the toner layer thickness on the developing roller 6 constant. A voltage of -430 V is applied to charge the one-component non-magnetic toner 4 and cause the one-component non-magnetic toner 4 to be attracted to the developing roller 6.

8 is the aforementioned elastic roller, which, like the developing roller 6, is made of high-molecular foamed polyurethane having a volume resistivity of 106 Ω·m and a hardness of 50° or less (measured with an Asker-C hardness meter).
The developing roller 6 is brought into contact with the developing roller 6 with the desired nip thickness.
Rotate in the same direction as arrow B.

In this example, the elastic roller 8 is applied with a voltage of -200V as a collection bias, mechanically and electrically collects the one-component non-magnetic toner 4 from the surface of the developing roller 6, and mechanically and electrically collects the one-component non-magnetic toner 4 from the surface of the developing roller 6. Eliminate electrical history.

In the above configuration, the elastic roller 8 has a pore diameter of 3
A foam is used in which minute foams of ~20 μm are formed so as to overlap each other.

This foam is made of polymeric polyurethane foam (for example, "Rubicell", a trade name manufactured by Toyo Polymer Co., Ltd.).

In this way, by setting the pore diameter of the elastic roller 8 to 3 to 20 μm, that is, twice or less the average particle diameter (10 μm) of the monocomponent nonmagnetic toner 4, the toner 4 is prevented from entering the inside and the function is improved. Prevents deterioration.

FIG. 3 is a characteristic diagram of one embodiment of the present invention, in which the vertical axis represents the development density (◯, D,), and the horizontal axis represents the number of times of development (number of sheets).

In the case of the present invention, foamed polyurethane with a pore diameter of 3 to 20 μm shown in FIG. 2 was used as the elastic opening 8, and as a comparative example, foamed polyurethane with a pore diameter of about 25 μm, which is more than twice as large, was used.

The other conditions were the same (ie, the conditions shown in FIG. 2), and the developed density was measured with respect to the number of times of development.

As shown in Figure 3, in the comparative example, as shown by the solid line,
The developed density (0°D, ) decreased significantly in proportion to the number of developing times, and it became below the allowable limit of developed density (0, D, = 1.2) after about 3000 developing times (3000 sheets). .

On the other hand, in the present invention, as shown by the dotted line, although the developed density slightly decreases with respect to the number of times of development, it hardly changes and remains above the allowable limit even after the number of times of development is 15,000 or more.

From this, if the pore diameter of the elastic roller 8 is larger than twice, toner clogging will not only occur in the surface layer, but will gradually progress inside the roller as printing is repeated, causing the elastic roller 8 to lose its elasticity. , the recovery function is impaired, 1-ner charging failure occurs, and the concentration becomes low.

This means that if the pore diameter of the elastic roller 8 is more than twice as large, the mutually supporting force of the toner particles becomes very small.
It is thought that toner has entered the inside.

On the other hand, in the case of the present invention, since the pore diameter of the elastic roller 8 is twice or less, the mutual supporting force of the toner particles acts sufficiently, and the toner clogging stops only on the surface of the elastic roller 8, which impairs the function. does not cause a decrease in

(b) Description of other embodiments FIG. 4 is a block diagram of another embodiment of the present invention.

In the figure, the same parts as those shown in FIG. 3 are indicated by the same symbols.

In this example, the elastic roller 8 transfers toner to the developing roller 6.
A supply bias voltage (-400V) is applied to the elastic roller 8 so as to electrically supply the voltage to the elastic roller 8.

Therefore, the moving direction of the surface of the elastic roller 8 is the same as that of the developing roller 6.
Since the elastic roller 8 rotates in the opposite direction and a supply bias of -400 cm is applied, at the initial stage of contact of the elastic roller 8,
The toner on the developing roller 6 is mechanically peeled off, and the toner is supplied both mechanically and electrically during subsequent contact.

In this example as well, the elastic roller 8 is
Since it is composed of a foam whose pore size is less than twice the average particle diameter of the one-component non-magnetic toner 4, it exhibits the same characteristics as shown in FIG. Clogging stops only on the surface, and does not cause a decrease in elasticity that impairs the feeding function.

(C) Description of another embodiment 1 In the above embodiment, a potential difference is provided between the developing roller 6 and the elastic roller 8, but the potential may be the same, and the photoconductor may be a negatively charged organic photoconductor. (OPC), the development bias voltage, toner supply bias voltage, and toner recovery bias voltage were all set to negative potentials. In this case, the developing bias voltage, toner supply bias voltage, and toner collection bias voltage may be set to positive potentials.

Although the present invention has been described above using examples, the present invention can be modified in various ways according to the gist of the present invention, and these are not excluded from the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, the elastic roller that comes into contact with the toner conveying body is constructed with pores that are less than twice the average particle diameter of the monocomponent toner, so that the toner particles support each other. Power is exerted, and the toner only gets clogged on the surface.
It is possible to prevent a decrease in flexibility that impairs the function, and it is possible to maintain good development characteristics over a long period of time.

[Brief explanation of drawings]

Figure 1 is a diagram of the principle of the present invention. FIG. 2 is a configuration diagram of an embodiment of the present invention. FIG. 3 is a characteristic diagram of an embodiment of the present invention. FIG. 4 is a block diagram of another embodiment of the present invention. In the figure, 1-latent image carrier; 6----)ner conveyor, 8 - Elastic roller.

Claims (1)

[Scope of Claims] A toner conveying body (6) that conveys monocomponent toner (4) to the latent image carrier (1) on which an electrostatic latent image is formed, and a toner conveying body (6) that is in contact with the toner conveying body (6), An elastic roller (8) for adhering to or peeling off the one-component toner (4) on the toner conveying body (6).
), in which the pore diameter of the elastic roller (8) is larger than that of the mono-component toner (4).
A one-component developing device characterized in that the average particle size is twice or less the average particle diameter of