JPH0437778A - One component system developing device - Google Patents

Abstract

PURPOSE:To prevent a developer having the reversed polarity and an outside addition agent from being collected in a developer supplying member and to obtain a stable copied image over a long period by providing a developer scratching off member in the vicinity of the developer supplying member. CONSTITUTION:The developer carried from the outside is uniformly supplied in an axis direction on the developer supplying member 3 by the supplying auger 4 of the bottom part of a developing machine. Then, the developer is transferred by the effect of an electric field with a potential difference on the pressurized-contact part of a developer carrying and developing roll 2 and the developer supplying member 3. The developer scratching off member 6 is formed with a L-shaped elastic body, and provided so that its one end abuts on the periphery of the developer supplying member 3 over the rotary axis direction of the developer supplying member. The developer having the reverse polarity and its outside addition agent stuck to the developer supplying member 3 are scratched off by the developer scratching off member 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device for developing electrostatic latent images, and more particularly to a dry-component developing device that does not use carrier particles.

(Prior Art) As a developing device for developing an electrostatic latent image formed on an electrostatic latent image holding member, there are two-component developing devices mainly composed of toner and carrier, and one-component developing device mainly composed of toner. Development has mainly been put into practical use. However, from the viewpoint of making the developing device itself more compact and improving maintainability, one-component developing methods and devices using a one-component developer consisting only of toner have been put into practical use, and in particular, toner From the viewpoint of high transparency, one-component development methods that do not use magnetic toner have been proposed.

A typical example of this is proposed in Japanese Patent Application Laid-Open No. 60-2967, in which a thin layer of developer is formed on the developer-carrying developing roll by a regulating member that presses against the developer-carrying developing roll. , non-magnetic-component development devices are known that impart a desired polarity of charge to the developer material.

In this -component developing device, since the developer is brought into pressure contact with each other while rotating and has a potential difference, the developer is sequentially transferred from the developer supply member to the developer carrying development roll. Supplied in rolls. and,
The developer supplied to the developer-carrying developing roll is formed into a thin layer by an appropriate regulating member, and at the same time is triboelectrically charged, and transferred to an electrostatic latent image carrier rotating in close proximity to the developer-carrying developing roll. Electrostatic adsorption to visualize the electrostatic latent image.

(Problem to be Solved by the Invention) However, in a copying machine equipped with a single-component developing device configured as described above, there is a problem in that poor reproduction of solid black areas in wide-area images occurs during the process of overlapping copies. was there.

Specifically, the developer is transferred from the supply member to the developer-carrying development roll by a potential difference provided between the developer-supply member and the developer-carrying development roll, and sufficient developer is supplied. Over time, the adhesion of the opposite polarity developer present in the developer and the charge control agent externally added to the developer to the developer supply member increases, resulting in a decrease in the electric field strength and the development process. In some cases, the agent cannot be transferred sufficiently, resulting in the above-mentioned problem.

To solve this problem, Japanese Utility Model Application Publication No. 64-23052 discloses that a developer supplying member is extended radially from a rotating shaft to a predetermined length, and a plurality of developer supplying members are provided in a portion thereof to carry developer. A one-component developing device has been proposed that includes a strip member and a developer scraping member that comes into contact with the strip member and removes the developer attached to the strip member. In this device, it was possible to remove toner adhesion to the strip member to some extent by using the detachment member, but it was necessary to increase the mechanical collision force between these two members, which meant that the toner adhesion to the strip member could be removed to some extent. With the use of the toner, there is a problem that some of the toner sticks to these members, there is also a problem that the rotational driving torque of the developer supply member is large, and when the toner has a high electric charge, I couldn't get away enough.

The present invention has been made to address these problems, and its purpose is to provide a one-component developing device that can always provide a stable copy density even after long-term use. be.

(Means for Solving the Problems) In order to solve the problems of the prior art described above, the one-component developing device of the present invention is such that the developer supplying member to the developer-carrying development roll and the developer-carrying development roll are in pressure contact with each other. , a rotating one-component developing device comprising a developer scraping member in contact with or near the developer supplying member, and a bias voltage applied to the scraping member. A one-component developing device is provided in which a developer scraping member for peeling off the developer adhering to the developer supplying member is provided in contact with or near the developer supplying member, and a bias is applied to the developer scraping member. It is characterized by providing

As a technical means for achieving this purpose, a fixing member is brought into contact with or close to the developer supplying member as a mechanical action, and an electric field is applied to the fixing member, and the developer is supplied by an electric action. This is a device that more efficiently scrapes off toner adhering to members.

The member that brings the fixing member into contact with the developer supply member may be a rod-shaped member, and these members may be rotating.

The voltage applied to these members is appropriately selected from direct current, alternating current, or a combination thereof. For example, the bias voltage to the fixing member is between 1.5 KV and 3.0 KV as an AC component between peak values. The OKV frequency can be 2 to 6 KHz, and the DC component can be the same value as the developer supply member or a higher value, for example, a value with 300 V added thereto.

(Function) In the developing device of the present invention, a developer stripping member is provided in contact with or in the vicinity of the developer supplying member, or the developer stripping member is further biased, preferably by applying a high frequency alternating electric field. By applying , the opposite polarity developer and the external additives of the developer do not adhere to and accumulate on the developer supply member over time, and the toner is always supplied to the developer supply member in the same manner as the initially set conditions. By stably supplying the developer from the toner supply member to the developer-carrying development roll, stable image quality can be obtained.

(Example) FIG. 1 shows a typical example of a one-component developing device to which the present invention is applied.

A developer carrying developing roll 2 and a developer supplying member 3 are rotatably supported while being in pressure contact with each other.

The developer supply member 3 includes a supply auger 4 at the bottom of the developing machine.
As a result, the developer transported from the outside is uniformly supplied in the axial direction. Then, the developer is transferred by the effect of an electric field due to a potential difference at a pressure contact portion between the developer carrying developing roll 2 and the developer supplying member 3. Then, the developer carrying developing roll 2
With the rotation of the toner regulating member 1, which moves while being held on the surface of the toner regulating member 1, which is fixed at one end and pressed against the developer-carrying developing roll, the toner is formed in a thin layer. , which is triboelectrically charged and further moves to the vicinity of the photoreceptor 7 holding the electrostatic latent image, thereby converting the latent image into a visible image.

The power supply 9 is a DC power supply between the developer carrying development roll 1 and the developer supply member 3 in order to improve development efficiency,
Reference numeral 8 denotes a developing bias power source applied between the developer-carrying developing roll 2 and the photoreceptor 7, and the photoreceptor 7 is electrically grounded to a frame (not shown) or the like.

6 is a developer scraping member characteristic of the present invention;
It is formed from an L-shaped elastic body, and one end thereof is provided so as to abut against the circumferential surface of the developer supply member 3 in the direction of the rotation axis of the developer supply member. The above-mentioned developer scraping member 6 scrapes off the opposite polarity developer adhering to the developer supply member 3 and the external additives of the developer.

Normally, toner has a positive or negative charge, so an external AC electric field of 2.0 KVpp, 2.5 KHz,
A peeling force is applied to the toner by applying a direct current of 250 cm. The above-mentioned member is
An L-shaped plate 6 as shown in FIG. 1 is arranged.

This makes it possible to realize strength suitable for the rotational force of the toner supply member 3 in a space-saving manner. By using the surface of this member as an insulating member and applying a high frequency electric field through the inner conductive member, it is possible to prevent electrical leakage from this member to the toner supply member 3.

Development was carried out under the following conditions using the one-component developing device having the above configuration.

The developer-carrying developing roll 2 is a 20 mm diameter SUS cylindrical member with a diameter of 12 mm coated with a phenol resin (carbon dispersion) having a thickness of 1 mm and a specific resistance of 106 ΩCm, and a 0.1 mm thick SUS plate spring is used for this. Material e, EPD
Layer forming member 1 of a soft elastic body with M rubber material adhered to
Welding was carried out at a pressure in the range of 500 g/am.

The developer supply member 3 is a cylindrical member made of SUS with a diameter of 6 mm and covered with a band-shaped urethane foam, and has an outer diameter of Φ15 m.
m, and a specific resistance of 106 Ωcm is used.

This was brought into close contact with the developer-carrying developing roll 2.

As the developer, one with e-polar particle size of 12 pm was used. Then, the photoreceptor 7 is rotated at 160 mm/s, and the developer carrying developing roll 2 is applied with a DC voltage of 2.0 KVp of 250 V.
It was rotated at a circumferential speed of 220 mm/s while applying a superimposed alternating current voltage of 2.5 KHz as a bias voltage.

Further, a DC voltage of 500 V was applied between the developer carrying developing roll 2 and the developer supplying member 3. The supply member 3 was rotated at 500 mm/s. Further, the developer scraping member is about 500 pm developer supply member 3.
brought into contact with. The bias applied to the scraping member 11 is 2. IKVpp and 2.5KHz.

Using the developing device configured in this example, 10KC/
A repeated copying test of V was conducted, and the level of density reduction at the wide area edge was evaluated as a density difference within one copy, and the results were as shown in FIG.

Compared to the conventional type without a scraping member, the embodiment of the present invention was able to maintain a stable concentration level over time. It was possible to reduce the concentration difference by providing only a scraping member, but this was not sufficient, and by applying a voltage to this scraping member,
It turned out to be more effective.

Although the absolute value of this experimental result differs depending on the composition of the toner, the effect shown in this figure could be observed relatively regardless of the material.

After this aging test 5KCv, changes in resistivity of the conventional developer supply member and the developer supply member of the type provided with a scraping member were measured, and the results are shown in FIG.

It has been found that in the absence of the scraping member, the resistance of the developer supply member increases as more copies are made. In order to investigate the cause of this, microscopic observation was performed. As a result, as shown in Fig. 4, there was a difference in the adhesion amount of the external additive with the opposite polarity to the developer e, and when a scraping member was provided, the e Since the opposite polarity developer is removed, the chargeability of the developer that has passed through the layer forming member 1 on the developer-carrying developing roll 2 is also improved, resulting in the effect of reducing clouds and obtaining good image quality without background fogging. was brought. In other words, it has been found that when the scraping member of the present invention and an electric field are applied to this member, the amount of charge is stable regardless of the number of copies.

Further, when the developing machine is arranged as shown in FIG. 1, the scraping member 5 can be installed in a spatial arrangement as shown in FIG. 5, that is, in a range of 270°.

FIG. 6 shows another preferred embodiment of the invention.

Although the configuration is similar to that shown in FIG. 11, it is suitable when strong stress cannot be applied due to the configuration and material of the developer supply member. A single-sided AI vapor-deposited insulating plate as shown in the figure is brought into contact with the toner supply member 3, a DC voltage of 250 V is applied to the supply material 3 to this AI section 11, and the plate is further peeled off from the developer supply member. In order to remove clogging of the developer, an AC voltage of 1.5KVp-p and a frequency of 2KHz are applied.
is applied.

In this configuration as well, good results were obtained as in the above-mentioned embodiments.

Further, as another preferred embodiment, as shown in FIG.
Similar results were obtained when the round rods 6 were placed at separate positions and DC and AC voltages were applied thereto.

As an example in this case, the round bar is made of SUS with a diameter of 2 mm.
Using , the development bias is set to 2. IKVp-p, and 2
．． I applied 5KHz. The tip bar may be fixed or may be rotatable. By doing this, in the same experiment as shown in Figure 2 above, 6KCV
Even after copying, it was possible to maintain a density difference of 0.1 or less.

(Effects of the Invention) In the one-component developing device of the present invention, a developer scraping member is provided in contact with or near the developer supply member, and the developer is scraped off from the developer supply member by applying a voltage. As a result, there is almost no accumulation of opposite polarity developer or external additives in the developer supply member, and the electric field effect due to the initial potential difference is sufficiently obtained, resulting in stable 1-
Since developer can be supplied at

The present invention can also be applied to recording devices such as printers.

[Brief explanation of the drawing]

FIG. 1, FIG. 6, and FIG. 7 show examples of the structure of the developing device of the present invention. Figure 2 compares the stability of solid images with and without a scraping member and with and without an electric field. FIG. 3 shows the change in resistance of the scraping member and the supply member over time depending on the presence or absence of electricity. FIG. 4 shows changes in the amount of charge on the developer over time with the presence or absence of a scraping member and due to the electric field. FIG. 5 shows the possible installation range of the scraping member. 1... Layer forming member, 2... Developer carrying development roll,
3...Developer supply member, 4...Supply auger,
5... Return auger, 6... Developer scraping member, 7... Photoreceptor, 8.・, bias power supply, 9...
DC power supply between developer carrying development roll and supply member

Claims (1)

[Claims] (1) In a one-component developing device in which the developer supply member to the developer-carrying development roll and the developer-carrying development roll are in pressure contact and are rotating, the developer is scraped off when it comes into contact with the developer supply member or in the vicinity. 1. A one-component developing device comprising a scraping member, wherein a bias voltage is applied to the scraping member.